diff --git a/marked/G/T-REC-G.1029-201402-I_PDF-E/raw.md b/marked/G/T-REC-G.1029-201402-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..2c6053b3aef303ed27b8b775c9955f808f402529 --- /dev/null +++ b/marked/G/T-REC-G.1029-201402-I_PDF-E/raw.md @@ -0,0 +1,553 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.1029** + +(02/2014) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Multimedia Quality of Service and performance – Generic +and user-related aspects + +# --- Voice service diagnosis framework + +Recommendation ITU-T G.1029 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.1029 + +# Voice service diagnosis framework + +## Summary + +Recommendation ITU-T G.1029 provides a framework and guidelines that describe how ITU-T speech quality assessment models can be used to identify common voice quality problems in live networks and how these can aid in diagnosing the cause of such problems once detected. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.1029 | 2014-02-13 | 12 | 11.1002/1000/12121 | + +## Keywords + +Cause analysis, ITU-T objective model, problem diagnosis, voice service. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2014 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Framework concept and architecture..... | 3 | +| 7 Introduction to speech quality measurement and assessment models ..... | 3 | +| 7.1 Subjective and objective testing ..... | 3 | +| 7.2 Classes of objective models..... | 5 | +| 7.3 Measurement configurations ..... | 7 | +| 8 Measurement data sources ..... | 8 | +| 8.1 Intrusive test probes..... | 8 | +| 8.2 Non-intrusive test probes..... | 8 | +| 8.3 Embedded probes ..... | 8 | +| 8.4 Additional metrics ..... | 8 | +| 8.5 Multi-point measurements..... | 9 | +| 8.6 Signalling related measurements ..... | 9 | +| 9 Decision process ..... | 9 | +| 9.1 Thresholds ..... | 9 | +| 9.2 Analysing metrics derived from live signals ..... | 9 | +| 9.3 Mapping basic diagnostic parameters into root cause analysis ..... | 10 | +| Appendix I – Example based on call clarity index ..... | 11 | +| Bibliography..... | 13 | + + + +# Voice service diagnosis framework + +# 1 Scope + +This Recommendation provides a framework and guidelines that describe how ITU-T speech quality assessment models can be used to identify common voice quality problems in live networks and how these can aid in diagnosing the cause of such problems once detected. The scope of this Recommendation is limited to voice service only. + +The Recommendation is intended to help non voice experts tasked with managing voice service and diagnosing voice quality problems, especially when voice is regarded as "just another IP application" on the network. + +The scope of this Recommendation relates to the perceived quality of the media stream; it does not include factors such as billing, availability, customer service, etc. The primary focus is point-to-point voice services; however, the methods and approaches described can also be applied to the individual legs of multi-party voice applications such as audio-conferencing. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T P.561] Recommendation ITU-T P.561 (2002), *In-service non-intrusive measurement device – Voice service measurements*. +- [ITU-T P.562] Recommendation ITU-T P.562 (2004), *Analysis and interpretation of INMD voice-service measurements*. +- [ITU-T P.563] Recommendation ITU-T P.563 (2004), *Single-ended method for objective speech quality assessment in narrow-band telephony applications*. +- [ITU-T P.564] Recommendation ITU-T P.564 (2007), *Conformance testing for voice over IP transmission quality assessment models*. +- [ITU-T P.800] Recommendation ITU-T P.800 (1996), *Methods for subjective determination of transmission quality*. +- [ITU-T P.800.1] Recommendation ITU-T P.800.1 (2006), *Mean Opinion Score (MOS) terminology*. +- [ITU-T P.800.2] Recommendation ITU-T P.800.2 (2013), *Mean opinion score interpretation and reporting*. +- [ITU-T P.862] Recommendation ITU-T P.862 (2001), *Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs*. +- [ITU-T P.862.1] Recommendation ITU-T P.862.1 (2003), *Mapping function for transforming P.862 raw result scores to MOS-LQO*. + +- [ITU-T P.862.2] Recommendation ITU-T P.862.2 (2007), *Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs.* +- [ITU-T P.863] Recommendation ITU-T P.863 (2011), *Perceptual objective listening quality assessment.* +- [ITU-T Y.1540] Recommendation ITU-T Y.1540 (2011), *Internet protocol data communication service – IP packet transfer and availability performance parameters.* +- [IETF RFC 3550] IETF RFC 3550 (2003), *RTP: A Transport Protocol for Real-Time Applications.* + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +None. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------------------|--------------------------------------------| +| CCI | Call Clarity Index | +| CQO | Conversational Quality Objective | +| ERL | Echo Return Loss | +| INMD | In-line Non-intrusive Measurement Device | +| IP | Internet Protocol | +| LQO | Listening Quality Objective | +| LQO N | Listening Quality Objective narrowband | +| LQO W | Listening Quality Objective wideband | +| LQO SWB | Listening Quality Objective super-wideband | +| LQS | Listening Quality Subjective | +| MOS | Mean Opinion Score | +| PCM | Pulse Code Modulation | +| PLC | Packet Loss Concealment | +| PSTN | Public Switched Telephone Network | +| RMON | Remote network Monitoring | +| RTCP | Real Time Control Protocol | +| RTCP XR | RTP Control Protocol extended Reports | +| RTP | Real time Transport Protocol | +| SIP | Session Initiation Protocol | +| UDP | User Datagram Protocol | +| VOIP | Voice Over IP | + +# 5 Conventions + +None. + +# 6 Framework concept and architecture + +This Recommendation provides a set of high level guidelines. It provides an introduction to speech quality measurement and assessment models, measurement data sources and general considerations relating to defining decision thresholds and mapping diagnostic values to the root cause of voice service problems. + +Appendix I is provided as an example and is used to illustrate some of the concepts described in this Recommendation. + +The ITU-T intends to provide two more Recommendations addressing, in detail, a framework for invoking diagnostic functions and a framework for mapping diagnostic parameters to root cause parameters, as follows: + +- Framework for invoking diagnostic functions: Identification of decision parameters that can be used to detect the presence of a media quality problem in a network so that a diagnostic function can be invoked. +- Framework for mapping diagnostic parameters to root cause parameters: This work item is concerned with mapping basic diagnostic parameters into root cause analysis parameters. + +Figure 1 shows the roadmap for the development of these two Recommendations. + +![Figure 1: Roadmap for further development of framework Recommendations. The diagram shows a flow from Terminals and Network through two framework boxes to QoE/QoS root-cause analysis parameters, with a Remedial action loop.](a234352dfaccdc24745c88eef7724cc6_img.jpg) + +The diagram illustrates the roadmap for the development of framework Recommendations. It shows a flow starting from 'Terminals' and 'Network' (represented by a cloud icon). The 'Terminals' and 'Network' feed into two main framework boxes. The top box, 'Framework for invoking diagnostic functions (Work Item 1)', contains 'QoE/QoS decision parameters' and 'Decision process'. The bottom box, 'Framework for mapping diagnostic parameters to root-cause parameters (Work Item 2)', contains 'QoE/QoS diagnostic parameters' and 'Diagnostic parameter to root-cause mapping'. An 'Invocation' arrow points from the 'Decision process' in the top box to the 'Diagnostic parameter to root-cause mapping' in the bottom box. The output of the bottom box is 'QoE/QoS root-cause analysis parameters'. A 'Remedial action' arrow points from the 'QoE/QoS root-cause analysis parameters' back to the 'Terminals' and 'Network'. The diagram is labeled G.1029(14)\_F01. + +Figure 1: Roadmap for further development of framework Recommendations. The diagram shows a flow from Terminals and Network through two framework boxes to QoE/QoS root-cause analysis parameters, with a Remedial action loop. + +Figure 1 – Roadmap for further development of framework Recommendations + +# 7 Introduction to speech quality measurement and assessment models + +## 7.1 Subjective and objective testing + +The perceived quality of a voice call is a subjective quantity. This means that the baseline for voice and audio quality is the subjective opinion of human listeners. One person's impression of "good" may be quite different to another person's impression, but neither is incorrect. Communications systems are therefore designed and tested against an "average" person's perception of voice quality. This is often summarized by the term mean opinion score (MOS). There are essentially two complementary approaches to measuring the quality of a voice signal as it will be perceived by the end user. These are: + +- Subjective testing +- Objective testing + +These two approaches are described in the following clauses. + +### 7.1.1 Subjective testing + +Subjective tests aim to find the average user's perception of the voice quality delivered by a communications system. This is done by asking a panel of users a directed question and providing them with a limited response choice. For example, to determine the listening quality of a voice signal, users are asked to rate "the quality of the speech" on a five-point discrete scale from bad to excellent as described in [ITU-T P.800]. + +The mean opinion score (MOS) for a particular test condition is calculated by averaging the votes of all subjects for that particular condition. A subjective test will typically contain many different conditions. Therefore, such tests take a long time to perform and the results are influenced by a wide range of factors. + +### 7.1.2 Objective testing + +Objective testing techniques measure physical properties of a system. Objective perceptual models map these physical properties to a predicted subjective score. In comparison with subjective testing, objective measurements are fast, inexpensive and repeatable. Significant work has led to objective prediction techniques that can be used in situations where it is impractical to perform formal subjective testing. + +### 7.1.3 MOS notation + +Voice subjective experiments are generally designed to either measure conversational quality or listening (one-way) quality. Conversational experiments investigate how effects such as delay, echo and level affect the ability of two people to carry out a conversation. Listening-only experiments are concerned with the perceived quality delivered by one side of a link and take into account factors such as distortion due to voice compression and packet loss. This distinction is also true for objective speech quality models and they can be designed to predict either listening quality or conversational quality. + +The ITU-T has defined terms to denote the difference between conversational and listening quality MOS values and the difference between MOS values from subjective experiments and MOS predictions made by objective models. The ITU-T notation defined in [ITU-T P.800.1] is shown in Table 1. The suffixes N (narrowband), W (wideband) and SWB (super-wideband)1 are also sometimes added to the notation to denote whether the subjective experiment, or predicted experiment, was conducted in a narrowband (300-3 400 Hz), wideband (50-7 000 Hz) or super-wideband (50-14 000 Hz) context respectively. For example, listening quality assessed in a narrowband context subjective experiment would be denoted as MOS-LQSN. + +The reader is also directed to [ITU-T P.800.2], which introduces some of the more common types of mean opinion score (MOS) and describes the minimum information that should accompany MOS values to enable them to be correctly interpreted. + +--- + +1 The SWB suffix is not explicitly mentioned in [ITU-T P.800.1], but the use of such extensions is encouraged where appropriate. + +**Table 1 – ITU-T MOS notation** + +| Description | Notation | +|--------------------------------------------------------|-----------------| +| Subjectively assessed listening quality | MOS-LQS | +| Subjectively assessed conversational listening quality | MOS-CQS | +| Objectively assessed listening quality | MOS-LQO | +| Objectively assessed conversational listening quality | MOS-CQO | + +## 7.2 Classes of objective models + +In general, objective voice quality models fall into one of four classes: full-reference, reduced-reference, no-reference or parametric. The following clauses introduce the main classes of models and introduce some of the relevant ITU-T Recommendations. Table 2 provides an overview of these Recommendations. + +**Table 2 – Summary of ITU-T objective voice quality model standards** + +| Model | Scope / brief definition | Input | Output | +|--------------------------------------------------------------------------|---------------------------------|----------------------------------------------------------------------------|--------------------------------------------------| +| [ITU-T P.863] | Full-reference model (LQO) | Reference and degraded 16-bit PCM signals, 8 and 48 kHz | MOS-LQO N ,
MOS-LQO SWB | +| [ITU-T P.862]
[ITU-T P.862.1]
[ITU-T P.862.2] | Full-reference model (LQO) | Reference and degraded 16-bit PCM signals, 8 and 16 kHz | MOS-LQO N ,
MOS-LQO W | +| [ITU-T P.561] | No-reference model (CQO) | PCM signals (for INMD classes A, B and C)
IP packets (for INMD class D) | Speech, noise and echo characterization | +| Annex A of [ITU-T P.562] | No-reference model (CQO) | ITU-T P.561 output | MOS-CQO N | +| [ITU-T P.563] | No-reference (LQO) | 8 kHz 16-bit PCM signal | MOS-LQO N | +| [ITU-T P.564] | Parametric (LQO) | RTP, UDP and IP headers | MOS-LQO N ,
MOS-LQO W | + +NOTE – This table lists only what is currently available and it is envisioned that this table will be updated. + +### 7.2.1 Full-reference models + +Full-reference objective models measure the impact on perceived voice quality of one or more network elements by comparing two versions of a test signal. As shown in Figure 2, the first signal is a copy of the original signal that was injected into the system under test; the second is the received signal, which has typically been degraded. Full-reference models can be used to measure the quality of a single network element, such as a codec, or an entire link, such as a mobile radio link. [ITU-T P.863] is an example of a full-reference objective voice model that predicts a listening quality MOS or MOS-LQO [ITU-T P.863]. + +![Figure 2: Diagram of an intrusive measurement configuration and a full-reference model. The diagram shows a 'Test signal injection' entering a 'Network element', which then enters another 'Network element'. 'Signal capture' points are shown after each network element. The first captured signal is labeled 'Captured signal (degraded input)' and the second is 'Copy of test signal (reference input)'. Both are inputs to a 'Full-reference model' block, which outputs a 'MOS prediction'. The diagram is labeled G.1029(14)_F02.](d4af765160d04ecef538e5066006dc77_img.jpg) + +``` + +graph LR + A[Test signal injection] --> B[Network element] + B --> C[Network element] + B --> D[Signal capture] + C --> E[Signal capture] + D --> F[Full-reference model] + E --> F + F --> G[MOS prediction] + style F fill:none,stroke:none + style G fill:none,stroke:none + +``` + +Figure 2: Diagram of an intrusive measurement configuration and a full-reference model. The diagram shows a 'Test signal injection' entering a 'Network element', which then enters another 'Network element'. 'Signal capture' points are shown after each network element. The first captured signal is labeled 'Captured signal (degraded input)' and the second is 'Copy of test signal (reference input)'. Both are inputs to a 'Full-reference model' block, which outputs a 'MOS prediction'. The diagram is labeled G.1029(14)\_F02. + +**Figure 2 – Diagram of an intrusive measurement configuration and a full-reference model** + +### 7.2.2 Reduced-reference models + +Reduced-reference models are similar to full-reference models, but use a reduced set of information about the original test signal rather than an exact copy. Reduced-reference models are typically used in applications where the reference signal is live traffic rather than a predetermined test signal, as shown in Figure 3. This means that information about the reference signal must be transmitted to the point of assessment if a comparison is to be made between the two. + +![Figure 3: Diagram of a non-intrusive measurement configuration and a reduced-reference model. The diagram shows 'Live traffic' entering a 'Network element', which then enters another 'Network element'. A dashed line labeled 'Information about traffic' is shown from the first network element. 'Signal capture' points are shown after each network element. The first captured signal is 'Captured signal (degraded input)' and the 'Information about traffic' is 'Information about traffic (reduced reference input)'. Both are inputs to a 'Reduced-reference model' block, which outputs a 'MOS prediction'. The diagram is labeled G.1029(14)_F03.](1439cb942d9e363bbb3161b5540dd8c6_img.jpg) + +``` + +graph LR + A[Live traffic] --> B[Network element] + B --> C[Network element] + B -.-> D[Information about traffic] + B --> E[Signal capture] + C --> F[Signal capture] + F --> G[Reduced-reference model] + D -.-> G + G --> H[MOS prediction] + style G fill:none,stroke:none + style H fill:none,stroke:none + +``` + +Figure 3: Diagram of a non-intrusive measurement configuration and a reduced-reference model. The diagram shows 'Live traffic' entering a 'Network element', which then enters another 'Network element'. A dashed line labeled 'Information about traffic' is shown from the first network element. 'Signal capture' points are shown after each network element. The first captured signal is 'Captured signal (degraded input)' and the 'Information about traffic' is 'Information about traffic (reduced reference input)'. Both are inputs to a 'Reduced-reference model' block, which outputs a 'MOS prediction'. The diagram is labeled G.1029(14)\_F03. + +**Figure 3 – Diagram of a non-intrusive measurement configuration and a reduced-reference model** + +### 7.2.3 No-reference models + +No-reference, or single-ended, models base their assessment on a single input signal and are typically used to monitor the quality of live traffic as shown in Figure 4. [ITU-T P.563] is an example of a no-reference objective speech model that predicts a listening quality MOS, or MOS-LQO [ITU-T P.563]; [ITU-T P.562] includes an example of a no-reference model that predicts conversational quality MOS, or MOS-CQO [ITU-T P.562]. + +![Figure 4: Diagram of a non-intrusive measurement configuration and a no-reference model. The diagram shows 'Live traffic' entering a 'Network element', which then enters another 'Network element'. 'Signal capture' points are shown after each network element. The first captured signal is 'Captured signal' and is input to a 'No-reference model' block, which outputs a 'MOS prediction'. The diagram is labeled G.1029(14)_F04.](78ffccd66df9bafd96e3e081110d09dd_img.jpg) + +``` + +graph LR + A[Live traffic] --> B[Network element] + B --> C[Network element] + B --> D[Signal capture] + C --> E[Signal capture] + E --> F[No-reference model] + F --> G[MOS prediction] + style F fill:none,stroke:none + style G fill:none,stroke:none + +``` + +Figure 4: Diagram of a non-intrusive measurement configuration and a no-reference model. The diagram shows 'Live traffic' entering a 'Network element', which then enters another 'Network element'. 'Signal capture' points are shown after each network element. The first captured signal is 'Captured signal' and is input to a 'No-reference model' block, which outputs a 'MOS prediction'. The diagram is labeled G.1029(14)\_F04. + +**Figure 4 – Diagram of a non-intrusive measurement configuration and a no-reference model** + +### 7.2.4 Parametric models + +Parametric models are designed to predict the impact of transmission impairments on the voice quality perceived by the end user of a system. Parametric models are no-reference models, but analyze parameters related to the underlying transmission system rather than the actual voice signal itself. For example, in the case of a voice over IP (VoIP) system, the main parameters will be derived from the packet loss and jitter characteristics of the link. Parametric voice quality models base their predictions on the assumption that the payload contains a typical, well-conditioned voice signal. + +Parametric models are useful in VoIP applications because simple measurements such as packet loss and jitter often correlate poorly with the quality perceived by the end-user. For example, 1% bursty packet loss may produce a number of mutes that will substantially degrade the voice quality perceived by the end-user; whereas 1% uniform packet loss may be largely concealed if the end-point includes an effective packet loss concealment (PLC) algorithm. + +An example of a parametric model is provided in [ITU-T P.564], which is concerned with a class of MOS-LQO prediction models that only analyse the IP/UDP/RTP header portion of the VoIP packets [ITU-T P.564]. This approach has several benefits including low-operational complexity and resilience to payload encryption. Note that [ITU-T P.564] does not specify a unique parametric model; it specifies minimum performance criteria that must be met by a model to achieve conformance with the Recommendation. + +## 7.3 Measurement configurations + +Objective measurement techniques can be categorized as either intrusive (active) or non-intrusive (passive). The distinction between classes of model and measurement configuration is often unclear because full-reference models are generally used in an intrusive configuration whilst no-reference and parametric models are used in a non-intrusive configuration. However, there can be exceptions to this rule, and so it is worth retaining the distinction. + +### 7.3.1 Intrusive (active) measurement + +In an intrusive measurement configuration a test signal is injected into the system under test and then captured and assessed at a later point as shown in Figure 2. + +Intrusive measurement is generally performed using a full-reference model because the test signal is known *a priori* and a copy can be stored at the assessment point. However, there is no reason in principal why a reduced-reference or no-reference model could not be used to measure the quality of the signal at the assessment point. + +Intrusive measurement is sometimes referred to as "active" measurement and can be used during the development, commissioning and routine monitoring of a communications service. Intrusive measurement configurations are also highly suitable for laboratory based testing because it is easy to isolate network components and inject and capture test signals. + +### 7.3.2 Non-intrusive (passive) measurement + +Non-intrusive measurement configurations are generally used to monitor live traffic, as shown in Figure 4. + +Non-intrusive measurement is typically performed using a no-reference or parametric model, although a reduced-reference model can also be used as described above. It is important that no-reference models can operate reliably over a very wide range of input signals because the input signal is not restricted to a carefully controlled test signal as it is with intrusive measurement. Parametric models avoid this issue because they do not use the voice signal in the quality calculation, but use an assumed voice signal instead. + +In VoIP testing, non-intrusive probes have visibility of all traffic at the monitoring point, including non-voice services. This can be useful in situations where the traffic profile is causing quality problems. For example, if VoIP traffic is transmitted with the wrong class-of-service marking, it may suffer from excessive jitter or packet loss due to the presence of other, non-voice traffic with the same marking. + +Non-intrusive measurement is sometimes referred to as "passive" measurement. + +# **8 Measurement data sources** + +## **8.1 Intrusive test probes** + +Intrusive test systems typically inject and capture at the edges of the network being tested, although it is possible to make multiple measurements from the same test signal as shown in Figure 2. + +Drive test systems are typically used to measure the voice quality of mobile systems as a function of geographical location. They comprise one or more central servers and a number of special mobile test devices. During each test call, a known test signal is sent in each direction and the received signal is processed by a full-reference model such as [ITU-T P.862] or [ITU-T P.863] to produce MOS-LQO values for each direction. Multiple MOS-LQO measurements may be made during each test call to improve measurement accuracy. + +VoIP test units are typically located at different points around the network and are configured to make scheduled test calls to each other. Such testing allows the ability of an IP network to carry VoIP traffic to be tested prior to the deployment of the actual VoIP system or at times when the system would otherwise be inactive. Such test arrangements can also be used to monitor live systems, although measurements are limited to the test traffic and not the customer traffic. + +## **8.2 Non-intrusive test probes** + +Non-intrusive, or passive, probes are generally used to monitor live network traffic. + +In a VoIP system, copies of packets may be taken at monitoring locations by means of a network tap or a mirror port configured on a switch or a router. VoIP streams can then be analysed using no-reference and/or parametric models to produce MOS-LQO and/or MOS-CQO values in addition to other voice diagnostic parameters, such as voice level, noise level, echo etc. + +Non-intrusive VoIP probes are typically located at key demarcation points in the network, such as public switched telephone network (PSTN) gateways, session initiation protocol (SIP) peering points, customer edge locations and conference bridges. Some vendors make signal quality measurements within the VoIP end-point. The methods by which such measurements are made available vary from vendor to vendor, but the aim is generally to send the measurements to a central point where the data can be analysed. The RTP control protocol extended reports (RTCP XR) mechanism defined in [b-IETF RFC 3611] describes a mechanism whereby measurements made at VoIP end-points are transported along the path taken by the voice packets and can thus be collected by monitoring probes at mid-network locations [b-IETF RFC 3611]. + +## **8.3 Embedded probes** + +In addition to statistics collected at the monitoring locations, many network elements are capable of making transmission measurements and reporting them to a central data collector. A number of vendors support the collection of IP flow based metrics, and some have been standardized by the IETF in the form of the remote network monitoring (RMON) family of RFCs. + +## 8.4 Additional metrics + +Quality problems caused by transmission impairments represent an important class of diagnostic information, and it is recommended that signal related metrics, such as MOS, voice level, noise level, echo, etc. are accompanied by associated transmission statistics. + +For example, in a VoIP system statistics relating to packet loss, jitter, out-of-sequence packets, round-trip delay and class-of-service markings all provide useful information when diagnosing problems that are the result of IP transmission problems. Such metrics are outside the scope of this Recommendation, but the reader is directed to the measurements defined in [ITU-T Y.1540] and the real-time control protocol (RTCP) measurements defined in [IETF RFC 3550]. + +## 8.5 Multi-point measurements + +The location of transmission problems that affect voice quality can be isolated by collecting and comparing measurements from multiple monitoring locations in the network. However, when performing such analysis, it is important to ensure that values such as MOS-LQO scores have been calculated using the same method or their comparison may be misleading. + +## 8.6 Signalling related measurements + +Signalling monitoring forms an important part of monitoring a VoIP deployment, but is outside the scope of this Recommendation. The ITU-T E-Series of Recommendations specify metrics that relate to signalling performance. + +# 9 Decision process + +Designing the optimum strategy for launching diagnostic processes will depend on the specific application, however the following points should be considered. + +## 9.1 Thresholds + +Detailed diagnostic or troubleshooting activities will generally be launched when one or more thresholds have been violated. Such thresholds may have absolute values or relative values, for example to detect deviations from normal operation. + +Many underlying problems will often only affect a subset of all calls. Hence applying thresholds to global averages across all calls may mean that decision thresholds are not violated because the problem traffic is too diluted. + +Invoking diagnostic analysis for every call that violates a threshold runs the risk of overwhelming the diagnostic function and generating "false-positive" alarms. This is especially true in the case of objective MOS values and other signal metrics derived from no-reference analysis of live calls (see clause 9.2). Thresholding the output of a parametric model might be appropriate in situations where there is little or no tolerance for transmission related quality problems. + +One means of achieving a balance is to define a threshold in terms of the proportion of calls that have violated an underlying threshold. For example, an alarm might be triggered if more than 10% of traffic in a given analysis period had a MOS-LQO value lower than 3.5. Such an approach can highlight problems that affect only a subset of calls, whilst still providing a degree of aggregation and protection from false-positive events. + +## 9.2 Analysing metrics derived from live signals + +Non-intrusive measurements provide an effective method of identifying systemic or underlying problems from live traffic measurements, i.e., problems that are consistently present, but it is important to ensure that a sufficient number of calls are analyzed before drawing any conclusions and invoking further diagnostic processes. Many factors relating to the quality of live customer calls + +naturally vary from call to call, for example the talker's speech characteristics, their acoustic environment, etc. This means that objective MOS values produced by a no-reference model will also naturally vary from call to call. The same is also true of other signal metrics calculated from live traffic, such as voice level, noise level and echo return loss. + +This inherent variability in signal related metrics means that inferences about system performance drawn from them for a single call are likely to be unreliable, and a suitable sample of calls should be used instead. However, it should be emphasized that since the main purpose of this type of analysis is to identify systemic issues, it is not necessary to analyse all calls – merely to ensure that a sufficient number of calls have been analysed. If a problem is systemic, analysis of a sub-sample of calls will be sufficient to identify the problem. + +The minimum sample size used in a decision process will depend on the decision mechanism and the natural variability of the metric being considered. Analysis of the standard deviation of a sample should provide an indication of how many samples are required to gain reliable results. The use of sampling can be applied both in the monitoring process that is used to invoke diagnostic functions, and in the diagnostic process itself. + +For example, if a contact centre were to change their headsets to models that were incorrectly matched to the agents' terminals, the conversational voice quality would be reduced due to sub-optimal voice levels. Such a systemic problem could be rapidly detected by analyzing a few hundred calls made to the contact centre, despite the fact that many thousands of calls could have been made in the same time interval. Further diagnostics, for example analysis of factors that contribute to conversational quality such as delay, echo, noise level and voice level, could also be based on a sub-sample of calls. + +## **9.3 Mapping basic diagnostic parameters into root cause analysis** + +The following factors should be considered when mapping between basic diagnostic parameters and the possible root cause of a problem: + +- What problems have been seen before and the likelihood of them occurring in the system being monitored +- Which diagnostic values are sensitive to a given underlying problem, and which are not +- The direction of problem voice flows and whether the equipment at the source of the flow is likely to generate a particular problem +- What proportion of flows are likely to be affected +- Equipment or configuration that is common to flows that have violated a particular threshold + +Table I.2 in Appendix I illustrates how [ITU-T P.561] and [ITU-T P.562] diagnostic parameters can be associated with common voice quality problems. For example, incorrectly set pads at interconnect points or handsets incorrectly matched to terminal devices are both common causes of very high or very low voice levels. For a given set of flows with an abnormal voice level, the likelihood of these two candidate root causes can be further separated by determining whether the source of the traffic is a gateway or a particular group of phones. + +The ability to group sets of measurements by common attributes can greatly assist in identifying the underlying root cause of a problem. This could be the type of equipment, source of configuration or physical location, depending on the particular root cause. For example, the ability to isolate all traffic flowing to and from a PSTN gateway or session border controller will greatly assist in detecting the root cause of common problems associated with these devices. + +Finally, it is important to recognize that the exact relationship between diagnostic parameters and possible root causes will often depend on the exact design and configuration of the voice service being monitored. + + + +# Appendix I + +## Example based on call clarity index + +(This appendix does not form an integral part of this Recommendation.) + +### Introduction to call clarity index + +The call clarity index (CCI) specified in Annex A of [ITU-T P.562] produces a MOS-CQO estimate of the conversational quality experienced at each end of a voice connection. The CCI output values are based on measurements of the voice level and the noise level in each direction, the echo return loss (ERL) at both ends of the connection and the roundtrip delay between the two ends. The inputs to CCI are taken from an in-line non-intrusive measurement device (INMD) conforming to [ITU-T P.561]. + +### Decision metric + +The percentage of calls with a CCI of $Y_C^A$ and $Y_C^B$ exceeding a MOS-CQO threshold. + +NOTE 1 – $Y_C^A$ denotes conversational speech quality as perceived from end A. + +NOTE 2 – $Y_C^B$ denotes conversational speech quality as perceived from end B. + +### Thresholds and alerting strategies + +In common with any alerting strategy involving live traffic, alerting based on a threshold violation by a single call is not recommended when monitoring traffic using CCI [ITU-T P.562]. Instead, it is generally more appropriate to raise an alert when a certain proportion of calls have violated a MOS-CQO threshold. + +Some factors that reduce conversational quality are outside the control of the service provider, for example if a user makes a call from a noisy location; however, such events are unlikely to affect all calls, whereas systematic problems will, by definition, impact a large proportion of calls handled by the problematic equipment or link. + +### Diagnostic parameters + +The [ITU-T P.561] inputs to the CCI algorithm are all useful diagnostic parameters and are listed in Table I.1. + +**Table I.1 – Diagnostic parameters associated with ITU-T P.562 call clarity index** + +| Name | Description | Units | +|-----------------|-----------------------------------------------------------|-------| +| SL A | INMD measured active speech level in direction A → B | dBm0 | +| SL B | INMD measured active speech level in direction B → A | dBm0 | +| NL A | INMD measured psophometric noise level in direction A → B | dBm0p | +| NL B | INMD measured psophometric noise level in direction B → A | dBm0p | +| EL A | INMD measured echo path loss for echo path A → B → A | dB | +| EL B | INMD measured echo path loss for echo path B → A → B | dB | +| ED A | INMD measured echo path delay for echo path A → B → A | ms | +| ED B | INMD measured echo path delay for echo path B → A → B | ms | + +### Interpretation and possible root causes + +A key factor in isolating the root cause of voice quality problems is the ability to analyse calls based on their source and destination. In particular, information about the route a call has taken before arriving at monitoring point that has raised an alert can be essential in diagnosing the root cause of the alert. + +If a particular route displays a large proportion of calls with a low CCI score, then further analysis is recommended by looking at the [ITU-T P.561] values associated with each CCI score. Note that low CCI scores will often be caused by a combination of factors, e.g., the presence of both echo and delay, or the combination of low voice levels and high noise levels. + +Some common causes of low a CCI score and the associated diagnostic parameters are listed in Table I.2. + +**Table I.2 – Diagnosing low call clarity index values** + +| Diagnostic | Example values | Possible causes | +|-------------------------------------------------------------------------|-----------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Presence of echo with a delay exceeding a few tens of milliseconds. | EL < 40 dB and
$ED^A + ED^B > 40$ ms |
  • Absence of echo cancellation or suppression equipment.
  • Echo control equipment erroneously disabled.
  • Echo tail length in echo canceller too short to echo path.
  • Acoustic echo from devices.
| +| Large round-trip delay. | $ED^A + ED^B > 500$ ms |
  • Excessive jitter on VoIP networks.
  • Unexpected call routing.
| +| Very high or very low voice level. | SL < -32 dBm0 or
SL > -8 dBm0 |
  • Incorrectly set pads at interconnect points or gateways.
  • Handsets incorrectly matched to terminal devices.
| +| Low signal-to-noise ratio due to low voice levels or high noise levels. | SL < -32 dBm0 or
NL > -50 dBm0p |
  • Large proportion of calls made from a noisy environment.
  • Also see low voice level.
| + +# Bibliography + +- [b-IETF RFC 3577] IETF RFC 3577 (2003), *Introduction to the Remote Monitoring (RMON) Family of MIB Modules.* +- [b-IETF RFC 3611] IETF RFC 3611 (2003), *RTP Control Protocol Extended Reports (RTCP XR).* +- [b-IETF RFC 3919] IETF RFC 3919 (2004), *Remote Network Monitoring (RMON) Protocol Identifiers for IPv6 and Multi Protocol Label Switching (MPLS).* +- [b-IETF RFC 5101] IETF RFC 5101 (2008), *Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.107-201506-I_PDF-E/raw.md b/marked/G/T-REC-G.107-201506-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..d467f10ba211113e0d9703019e425681646f57a7 --- /dev/null +++ b/marked/G/T-REC-G.107-201506-I_PDF-E/raw.md @@ -0,0 +1,804 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.107** + +(06/2015) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +International telephone connections and circuits – +Transmission planning and the E-model + +# --- **The E-model: a computational model for use in transmission planning** + +Recommendation ITU-T G.107 + +## ITU-T G-SERIES RECOMMENDATIONS + +## TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| Transmission planning and the E-model | G.100–G.109 | +| General Recommendations on the transmission quality for an entire international telephone connection | G.110–G.119 | +| General characteristics of national systems forming part of international connections | G.120–G.129 | +| General characteristics of the 4-wire chain formed by the international circuits and national extension circuits | G.130–G.139 | +| General characteristics of the 4-wire chain of international circuits; international transit | G.140–G.149 | +| General characteristics of international telephone circuits and national extension circuits | G.150–G.159 | +| Apparatus associated with long-distance telephone circuits | G.160–G.169 | +| Transmission plan aspects of special circuits and connections using the international telephone connection network | G.170–G.179 | +| Protection and restoration of transmission systems | G.180–G.189 | +| Software tools for transmission systems | G.190–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +For further details, please refer to the list of ITU-T Recommendations. + +### Recommendation ITU-T G.107 + +# The E-model: a computational model for use in transmission planning + +## Summary + +Recommendation ITU-T G.107 gives the algorithm for the so-called E-model as the common ITU-T transmission rating model. This computational model can be useful to transmission planners, to help ensure that users will be satisfied with end-to-end transmission performance. The primary output of the model is a scalar rating of transmission quality. A major feature of this model is the use of transmission impairment factors that reflect the effects of modern signal processing devices. + +In the 2000 version of this Recommendation, an enhanced version of the E-model was provided in order to better take into account the effects of room noise at the send side and quantizing distortion. With the 2002 version, the impairment due to random packet loss was included in a parametric way for different codecs. Since the 2003 version, an enhanced modelling of quality in the case of low talker sidetone levels is provided. The 2005 version enabled more accurate quality predictions for codecs under (short-term) dependent packet loss. The 2009 version included an Appendix II describing a provisional impairment factor framework for wideband speech transmission. In 2011, this appendix was updated in favour of a new Recommendation ITU-T G.107.1. In the current version, the model has been extended to provide an assessment of delay impairments that is also better tailored to less delay-sensitive use cases. Carrier-grade or enterprise-grade telephony systems must be assessed with the default delay sensitivity parameters, while communication systems with low or very low interactivity requirements can be assessed with different parameters. A reference implementation is given in Appendix III. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|---------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.107 | 1998-12-03 | 12 | 11.1002/1000/4541 | +| 2.0 | ITU-T G.107 | 2000-05-18 | 12 | 11.1002/1000/5074 | +| 3.0 | ITU-T G.107 | 2002-07-14 | 12 | 11.1002/1000/6080 | +| 4.0 | ITU-T G.107 | 2003-03-16 | 12 | 11.1002/1000/6253 | +| 5.0 | ITU-T G.107 | 2005-03-01 | 12 | 11.1002/1000/7822 | +| 5.1 | ITU-T G.107 (2005) Amd. 1 | 2006-06-13 | 12 | 11.1002/1000/8864 | +| 6.0 | ITU-T G.107 | 2008-08-29 | 12 | 11.1002/1000/9538 | +| 7.0 | ITU-T G.107 | 2009-04-29 | 12 | 11.1002/1000/9730 | +| 8.0 | ITU-T G.107 | 2011-12-14 | 12 | 11.1002/1000/11460 | +| 8.1 | ITU-T G.107 (2011) Amd. 1 | 2012-06-07 | 12 | 11.1002/1000/11707 | +| 9.0 | ITU-T G.107 | 2014-02-13 | 12 | 11.1002/1000/12120 | +| 10.0 | ITU-T G.107 | 2015-06-29 | 12 | 11.1002/1000/12505 | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2015 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +| | | Page | +|--------------|-----------------------------------------------------------------------------------------------------------------------------------|------| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Conventions ..... | 2 | +| 6 | The E-model, a computational model for use in transmission planning ..... | 2 | +| 6.1 | Introduction ..... | 2 | +| 7 | Structure and basic algorithms of the E-model..... | 3 | +| 7.1 | Calculation of the transmission rating factor, R..... | 4 | +| 7.2 | Basic signal-to-noise ratio, Ro ..... | 4 | +| 7.3 | Simultaneous impairment factor, Is..... | 5 | +| 7.4 | Delay impairment factor, Id ..... | 5 | +| 7.5 | Equipment impairment factor, Ie..... | 7 | +| 7.6 | Advantage factor, A..... | 8 | +| 7.7 | Default values..... | 9 | +| Annex A | Conditions for using the E-model..... | 11 | +| A.1 | Examples of conditions where caution must be exercised when using the E-model ..... | 11 | +| A.2 | Conditions for which the performance of the E-model has been improved by updating from the earlier version ..... | 12 | +| Annex B | – Quality measures derived from the transmission rating factor R ..... | 15 | +| Appendix I | – Calculation of R from MOS CQE values ..... | 17 | +| Appendix II | – Provisional impairment factor framework for wideband speech transmission ..... | 18 | +| Appendix III | – Reference implementation of the E-model in ITU-T G.107 ..... | 19 | +| Appendix IV | – Use of the E-model in conjunction with noise reduction or echo canceller systems in the network or the terminal equipment ..... | 20 | +| Bibliography | ..... | 22 | + + + +# The E-model: a computational model for use in transmission planning + +# 1 Scope + +This Recommendation describes a computational model, known as the E-model, that has proven useful as a transmission planning tool for assessing the combined effects of variations in several transmission parameters that affect the conversational1 quality of 3.1 kHz handset telephony. This computational model can be used, for example, by transmission planners to help ensure that users will be satisfied with end-to-end transmission performance whilst avoiding over-engineering of networks. It must be emphasized that the primary output from the model is the "rating factor" $R$ but this can be transformed to give estimates of customer opinion. Such estimates are only made for transmission planning purposes and not for actual customer opinion prediction (for which there is no agreed-upon model recommended by the ITU-T). + +The E-model can be used with confidence for many combinations of high importance to transmission planners, but for some parameter combinations of high importance, E-model predictions have been questioned and are currently under study. Annex A provides further information in this regard. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.107.1] Recommendation ITU-T G.107.1 (2015), *Wideband E-model*. +<> +- [ITU-T G.108] Recommendation ITU-T G.108 (1999), *Application of the E-model: A planning guide*. +<> +- [ITU-T G.109] Recommendation ITU-T G.109 (1999), *Definition of categories of speech transmission quality*. +<> +- [ITU-T G.113] Recommendation ITU-T G.113 (2007), *Transmission impairments due to speech processing*. +<> +- [ITU-T P.833] Recommendation ITU-T P.833 (2001), *Methodology for derivation of equipment impairment factors from subjective listening-only tests*. +<> + +--- + +1 Conversational quality in this context refers to transmission characteristics, e.g., long transmission times, effects of talker echoes, etc. However, the E-model, as described in this Recommendation, is not intended to model transmission impairments during double talk situations. + +- [ITU-T P.834] Recommendation ITU-T P.834 (2015), *Methodology for the derivation of equipment impairment factors from instrumental models*. +<> +- [ITU-T P.863] Recommendation ITU-T P.863 (2014), *Perceptual objective listening quality assessment*. +<> + +# **3 Definitions** + +## **3.1 Terms defined elsewhere** + +None. + +## **3.2 Terms defined in this Recommendation** + +None. + +# **4 Abbreviations and acronyms** + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------|--------------------------------------------------------| +| BurstR | Burst Ratio | +| GoB | Good or Better | +| LSTR | Listener Sidetone Rating | +| MOS | Mean Opinion Score | +| MNRU | Modulated Noise Reference Unit | +| OLR | Overall Loudness Rating | +| OPINE | Overall Performance Index model for Network Evaluation | +| PLC | Packet Loss Concealment | +| PoW | Poor or Worse | +| qdu | quantization distortion unit | +| RLR | Receive Loudness Rating | +| SLR | Send Loudness Rating | +| STMR | Sidetone Masking Rating | +| TELR | Talker Echo Loudness Rating | +| WEPL | Weighted Echo Path Loss | + +# **5 Conventions** + +None. + +# **6 The E-model, a computational model for use in transmission planning** + +## **6.1 Introduction** + +The complexity of modern networks requires not only that, for transmission planning, each of the many transmission parameters be considered individually but also that their combined effects be taken into account. This can be done by "expert, informed guessing", but a more systematic approach is desirable, such as by using a computational model. The output from the model described here is a + +scalar quality rating value, $R$ , which varies directly with the overall conversational quality. [ITU-T G.113] gives guidance about specific impairments, including combined effects based upon a simplification of the model. However, the output can also give nominal estimates of the user reactions, for instance in the form of percentages finding the modelled connection good or better (GoB) or poor or worse (PoW), as described in Annex B. Furthermore, detailed guidance on the proper application of the E-model, as described in this Recommendation, is provided in [ITU-T G.108]. In addition, the definition of categories of speech transmission quality can be found in [ITU-T G.109]. + +# 7 Structure and basic algorithms of the E-model + +The E-model is based on the equipment impairment factor method, following previous transmission rating models. It was developed by an ETSI ad hoc group called "Voice Transmission Quality from Mouth to Ear". + +The reference connection, as shown in Figure 1, is split into a send side and a receive side. The model estimates the conversational quality from mouth to ear as perceived by the user at the receive side, both as listener and talker. + +![Figure 1 – Reference connection of the E-model. The diagram shows a 'Send side' on the left and a 'Receive side' on the right, connected by a central network block. On the send side, a user icon is connected to a 'Ds-factor' block, which is also influenced by 'Room noise Ps'. The signal then enters the network block. The network block contains a 'Weighted echo path loss WEPL' and 'Round-trip delay Tr' loop, a 'Coding/decoding' block, and is influenced by 'Circuit noise Nc referred to 0 dBr', 'Equipment impairment factor Ie', 'Packet-loss probability Ppl', and 'Packet-loss robustness factor Bpl'. The signal exits the network block to the receive side, passing through a 'Dr-factor' block influenced by 'Room noise Pr'. The receive side also includes 'Sidetone masking rating STMR', 'Listener sidetone rating LSTR (LSTR = STMR + Dr)', and 'Talker echo loudness rating TELR'. Horizontal double-headed arrows at the top indicate 'OLR' (Overall Loudness Rating) as the sum of 'SLR' (Send Loudness Rating) and 'RLR' (Receive Loudness Rating). Other horizontal arrows indicate 'Mean one-way delay T', 'Absolute delay Ta', 'Quantizing distortion qdu', and 'Expectation factor A'. A '0 dBr point' is marked at the network interface. The diagram is labeled 'G.107(08)_F01' at the bottom right.](7a0db9703b68b3d06cdaeefc084c0006_img.jpg) + +Figure 1 – Reference connection of the E-model. The diagram shows a 'Send side' on the left and a 'Receive side' on the right, connected by a central network block. On the send side, a user icon is connected to a 'Ds-factor' block, which is also influenced by 'Room noise Ps'. The signal then enters the network block. The network block contains a 'Weighted echo path loss WEPL' and 'Round-trip delay Tr' loop, a 'Coding/decoding' block, and is influenced by 'Circuit noise Nc referred to 0 dBr', 'Equipment impairment factor Ie', 'Packet-loss probability Ppl', and 'Packet-loss robustness factor Bpl'. The signal exits the network block to the receive side, passing through a 'Dr-factor' block influenced by 'Room noise Pr'. The receive side also includes 'Sidetone masking rating STMR', 'Listener sidetone rating LSTR (LSTR = STMR + Dr)', and 'Talker echo loudness rating TELR'. Horizontal double-headed arrows at the top indicate 'OLR' (Overall Loudness Rating) as the sum of 'SLR' (Send Loudness Rating) and 'RLR' (Receive Loudness Rating). Other horizontal arrows indicate 'Mean one-way delay T', 'Absolute delay Ta', 'Quantizing distortion qdu', and 'Expectation factor A'. A '0 dBr point' is marked at the network interface. The diagram is labeled 'G.107(08)\_F01' at the bottom right. + +Figure 1 – Reference connection of the E-model + +The transmission parameters used as an input to the computation model are shown in Figure 1. Values for room noise and for the $D$ -factors are handled separately in the algorithm for the send side and receive side and may be of different amounts. The parameters send loudness rating (SLR), receive loudness rating (RLR) and circuit noise $N_c$ are referred to a defined 0 dBr point. All other input parameters are either considered as values for the overall connection, such as overall loudness rating (OLR), i.e., the sum of SLR and RLR, number of qdu, equipment impairment factors $I_e$ and advantage factor $A$ , or referred to only for the receive side, such as sidetone masking rating (STMR), listener sidetone rating (LSTR), weighted echo path loss (WEPL) used for the calculation of listener echo and talker echo loudness rating (TELR). + +There are three different parameters associated with transmission time. The absolute delay $T_a$ represents the total one-way delay between the send side and receive side and is used to estimate the + +impairment due to excessive delay. The parameter mean one-way delay $T$ represents the delay between the receive side (in talking state) and the point in a connection where a signal coupling occurs as a source of echo. The round-trip delay $Tr$ only represents the delay in a 4-wire loop, where the "double reflected" signal will cause impairments due to listener echo. + +## 7.1 Calculation of the transmission rating factor, $R$ + +According to the equipment impairment factor method, the fundamental principle of the E-model is based on a concept given in the description of the OPINE model, see [b-ITU-T P-Sup.3]. + +Psychological factors on the psychological scale are additive. + +The result of any calculation with the E-model in a first step is a transmission rating factor $R$ , which combines all transmission parameters relevant for the considered connection. This rating factor $R$ is composed of: + +$$R = Ro - Is - Id - Ie\text{-eff} + A \quad (7-1)$$ + +$Ro$ represents in principle the basic signal-to-noise ratio, including noise sources such as circuit noise and room noise. Factor $Is$ is a combination of all impairments which occur more or less simultaneously with the voice signal. Factor $Id$ represents the impairments caused by delay and the effective equipment impairment factor $Ie\text{-eff}$ represents impairments caused by low bit-rate codecs. It also includes impairment due to randomly distributed packet losses. The advantage factor $A$ allows for compensation of impairment factors when the user benefits from other types of access to the user. The term $Ro$ and the $Is$ and $Id$ values are subdivided into further specific impairment values. The following clauses give the equations used in the E-model. + +## 7.2 Basic signal-to-noise ratio, $Ro$ + +The basic signal-to-noise ratio $Ro$ is defined by: + +$$Ro = 15 - 1.5(SLR + No) \quad (7-2)$$ + +The term $No$ (in [dBm0p]) is the power addition of different noise sources: + +$$No = 10 \log \left[ 10^{\frac{Nc}{10}} + 10^{\frac{Nos}{10}} + 10^{\frac{Nor}{10}} + 10^{\frac{Nfo}{10}} \right] \quad (7-3)$$ + +$Nc$ (in [dBm0p]) is the sum of all circuit noise powers, all referred to the 0 dBr point. + +$Nos$ (in [dBm0p]) is the equivalent circuit noise at the 0 dBr point, caused by the room noise $Ps$ at the send side: + +$$Nos = Ps - SLR - Ds - 100 + 0.004(Ps - OLR - Ds - 14)^2 \quad (7-4)$$ + +where $OLR = SLR + RLR$ . In the same way, the room noise $Pr$ at the receive side is transferred into an equivalent circuit noise $Nor$ (in [dBm0p]) at the 0 dBr point. + +$$Nor = RLR - 121 + Pre + 0.008(Pre - 35)^2 \quad (7-5)$$ + +The term $Pre$ (in [dBm0p]) is the "effective room noise" caused by the enhancement of $Pr$ by the listener's sidetone path: + +$$Pre = Pr + 10 \log \left[ 1 + 10^{\frac{(10 - LSTR)}{10}} \right] \quad (7-6)$$ + +$Nfo$ (in [dBm0p]) represents the "noise floor" at the receive side, + +$$Nfo = Nfor + RLR \quad (7-7)$$ + +with $N_{for}$ usually set to $-64$ dBmp. + +## 7.3 Simultaneous impairment factor, $I_s$ + +The factor $I_s$ is the sum of all impairments which may occur more or less simultaneously with the voice transmission. The factor $I_s$ is divided into three further specific impairment factors: + +$$I_s = I_{olr} + I_{st} + I_q \quad (7-8)$$ + +$I_{olr}$ represents the decrease in quality caused by too-low values of OLR and is given by: + +$$I_{olr} = 20 \left[ \left\{ 1 + \left( \frac{X_{olr}}{8} \right)^8 \right\}^{\frac{1}{8}} - \frac{X_{olr}}{8} \right] \quad (7-9)$$ + +where: + +$$X_{olr} = OLR + 0.2(64 + N_o - RLR) \quad (7-10)$$ + +The factor $I_{st}$ represents the impairment caused by non-optimum sidetone: + +$$I_{st} = 12 \left[ 1 + \left( \frac{STMRO - 13}{6} \right)^8 \right]^{\frac{1}{8}} - 28 \left[ 1 + \left( \frac{STMRO + 1}{19.4} \right)^{35} \right]^{\frac{1}{35}} - 13 \left[ 1 + \left( \frac{STMRO - 3}{33} \right)^{13} \right]^{\frac{1}{13}} + 29 \quad (7-11)$$ + +where: + +$$STMRO = -10 \log \left[ 10^{-\frac{STM R}{10}} + e^{-\frac{T}{4}} 10^{-\frac{TELR}{10}} \right] \quad (7-12)$$ + +The impairment factor $I_q$ represents impairment caused by quantizing distortion: + +$$I_q = 15 \log [1 + 10^Y + 10^Z] \quad (7-13)$$ + +where: + +$$Y = \frac{R_o - 100}{15} + \frac{46}{8.4} - \frac{G}{9} \quad (7-14)$$ + +$$Z = \frac{46}{30} - \frac{G}{40} \quad (7-15)$$ + +and: + +$$G = 1.07 + 0.258Q + 0.0602Q^2 \quad (7-16)$$ + +$$Q = 37 - 15 \log(qdu) \quad (7-17)$$ + +In this equation, qdu means the number of qdu for the whole connection between the send side and the receive side. + +NOTE – If an impairment factor $I_e$ is used for a piece of equipment, then the qdu value for that same piece of equipment must not be used. + +## 7.4 Delay impairment factor, $I_d$ + +The impairment factor $I_d$ representing all impairments due to delay of voice signals is also further divided into three factors: $I_{dte}$ , $I_{dle}$ and $I_{dd}$ , where + +$$I_d = I_{dte} + I_{dle} + I_{dd} \quad (7-18)$$ + +The factor *Idte* gives an estimate for the impairments due to the talker echo: + +$$Idte = \left[ \frac{Roe - Re}{2} + \sqrt{\frac{(Roe - Re)^2}{4} + 100} - 1 \right] (1 - e^{-T}) \quad (7-19)$$ + +where: + +$$Roe = -1.5(No - RLR) \quad (7-20)$$ + +$$Re = 80 + 2.5(TERV - 14) \quad (7-21)$$ + +$$TERV = TELR - 40 \log \frac{1 + \frac{T}{10}}{1 + \frac{T}{150}} + 6e^{-0.3T^2} \quad (7-22)$$ + +For values of $T < 1$ ms, the talker echo should be considered as sidetone, i.e., $Idte = 0$ . The computation algorithm furthermore combines the influence of STMR to talker echo. Taking into account that low values of STMR may have some masking effects on the talker echo and, for very high values of STMR, the talker echo may become more noticeable, the terms *TERV* and *Idte* are adjusted as follows: + +For STMR < 9 dB: + +In Equation 7-21, *TERV* is replaced by *TERVs*, where: + +$$TERVs = TERV + \frac{Ist}{2} \quad (7-23)$$ + +For $9 \text{ dB} \leq \text{STMR} \leq 20 \text{ dB}$ : + +Equations 7-19 to 7-22 apply. + +For STMR > 20 dB: + +In Equation 7-18, *Idte* is replaced by *Idtes*, where: + +$$Idtes = \sqrt{Idte^2 + Ist^2} \quad (7-24)$$ + +The factor *Idle* represents impairments due to listener echo. The equations are: + +$$Idle = \frac{Ro - Rle}{2} + \sqrt{\frac{(Ro - Rle)^2}{4} + 169} \quad (7-25)$$ + +where: + +$$Rle = 10.5(WEPL + 7)(Tr + 1)^{-0.25} \quad (7-26)$$ + +The factor *Idd* represents the impairment caused by too-long absolute delay *Ta*, which occurs even with perfect echo cancelling. Only when the effect due to pure delay is attributed to the service, is the effect, to some extent, reflected in the respective speech quality evaluation by the user. It is noted that the effect due to pure delay may instead be attributed to the other conversation partner, or may be attributed to a conversational difficulty; for example if the conversation partners do not know each other, or delay may simply reduce the efficiency of the communication. In the current version of the E-model, different types of conversations and/or users are considered, in terms of their interactivity and delay-sensitivity. As a consequence, the predictions can be tailored to the delay sensitivity requirements of the user group. + +For $Ta \leq mT$ : + +$$I_{dd} = 0$$ + +For $T_a > mT$ : + +$$I_{dd} = 25 \left\{ \left( 1 + X^{6 \cdot sT} \right)^{\frac{1}{6 \cdot sT}} - 3 \left( 1 + \left[ \frac{X}{3} \right]^{6 \cdot sT} \right)^{\frac{1}{6 \cdot sT}} + 2 \right\} \quad (7-27)$$ + +with: + +$$X = \frac{\log \left( \frac{T_a}{mT} \right)}{\log 2} \quad (7-28)$$ + +The following fixed settings of delay sensitivity, $sT$ and minimum perceivable delay, $mT$ , are recommended, reflecting different use cases and user groups. Two aspects are addressed by these settings: + +- The interactivity of the conversation and the sensitivity of the users to the delay-effect. +- The application scenario, that is, whether a given call is being made in a business context or in an everyday situation. Even if users may not notice the delay, it may be very critical for the efficiency or even effectiveness of a given call, for example in a business context. + +As a consequence, in the case where it is uncertain what user group or what application scenario is being addressed with the planned service, it is recommended that the default class is used. Any case of non-default value usage should be explicitly mentioned when reporting results. + +Based on these considerations, the following settings, shown in Table 1, are recommended for $sT$ and $mT$ : + +**Table 1 – Delay-sensitivity classes for different use cases** + +| Class of delay-sensitivity | $sT$ | $mT$ (ms) | Use case | +|----------------------------|------|-----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Default | 1 | 100 |
  • – Applicable to all types of telephone conversations.
  • – Must be used for:
    • • Carrier-grade fixed or mobile telephony;
    • • Enterprise-grade fixed or mobile telephony;
    • • When targeted user group and delay requirements are unknown.
| +| Low | 0.55 | 120 |
  • – Applicable only in cases where it is known that users have low sensitivity to delay, e.g., non time-sensitive conversation scenarios.
| +| Very low | 0.4 | 150 |
  • – Applicable only in cases where it is known that users have very low sensitivity to delay, e.g., in primarily non-interactive cases, such as mainly listening to a conversation or to a lecture.
| + +## 7.5 Equipment impairment factor, $I_e$ + +The values for the equipment impairment factor $I_e$ of elements using low bit-rate codecs are not related to other input parameters. They depend on subjective mean opinion score (MOS) test results as well as on network experience. Refer to Appendix I of [ITU-T G.113] for the currently recommended values of $I_e$ . + +Specific impairment factor values for codec operation under random2 packet-loss have formerly been treated using tabulated, packet-loss dependent *Ie*-values. Now, the packet-loss robustness factor *Bpl* is defined as a codec-specific value. The packet-loss dependent effective equipment impairment factor *Ie-eff* is derived using the codec-specific value for the equipment impairment factor at zero packet-loss *Ie* and the packet-loss robustness factor *Bpl*, both listed in Appendix I of [ITU-T G.113] for several codecs. With the packet-loss probability *Ppl*, *Ie-eff* is calculated using the equation: + +$$Ie-eff = Ie + (95 - Ie) \cdot \frac{Ppl}{\frac{Ppl}{BurstR} + Bpl} \quad (7-29)$$ + +*BurstR* is the so-called burst ratio, which is defined as: + +$$BurstR = \frac{\text{Average length of observed bursts in an arrival sequence}}{\text{Average length of bursts expected for the network under "random" loss}}$$ + +When packet loss is random (i.e., independent) *BurstR* = 1; and + +when packet loss is bursty (i.e., dependent) *BurstR* > 1. + +For example, for packet loss distributions corresponding to a 2-state Markov model with transition probabilities *p* between a "found" and a "loss" state, and *q* between the "loss" and the "found" state, the burst ratio can be calculated as: + +$$BurstR = \frac{1}{p + q} = \frac{Ppl / 100}{p} = \frac{1 - Ppl / 100}{q} \quad (7-30)$$ + +As can be seen from Equation 7-29, the effective equipment impairment factor in the case of *Ppl* = 0 (no packet-loss) is equal to the *Ie* value defined in Appendix I of [ITU-T G.113]. + +Please refer to Annex A for the range of parameter values the algorithm has been validated for. + +*Ie-eff* should be derived by using the *Ie* and *Bpl* values if they are provided in [ITU-T G.113] and the packet-loss burstiness can be defined by observing packet-loss characteristics. If, for practical reasons, it is difficult to observe the packet-loss rate (*Ppl*) and/or packet-loss characteristics to derive the burstiness parameter (*BurstR*), the [ITU-T P.834] approach can be used to directly derive *Ie-eff*. + +If *Ie* is derived directly by using the instrumental method recommended in [ITU-T P.834], it already reflects the effect of packet loss introduced in the preparation of speech materials under test. Therefore, Equation 7-29 should not be used. Rather, the *Ie* value derived by [ITU-T P.834] in *Ie-eff* in Equation 7-1 should be used. + +## 7.6 Advantage factor, A + +Due to the specific meaning of the advantage factor *A*, there is consequently no relation to any of the other transmission parameters. Some provisional values are given in Table 2. + +2 The probability of losing a packet is regarded as independent of the reception state (received/lost) of the previous packet. + +**Table 2 – Provisional examples for the advantage factor *A*** + +| Communication system example | Maximum value of A | +|------------------------------------------------------------------------------|---------------------------| +| Conventional (wirebound) | 0 | +| Mobility by cellular networks in a building | 5 | +| Mobility in a geographical area or moving in a vehicle | 10 | +| Access to hard-to-reach locations, e.g., via multi-hop satellite connections | 20 | + +It should be noted that the values in Table 2 are only provisional. The use of factor *A* and its selected value in a specific application is the planner's decision. However, the values in Table 2 should be considered as absolute upper limits for *A*. Additional background information on the advantage factor *A* can be found in Appendix II to [ITU-T G.113]. + +## 7.7 Default values + +The default values for all input parameters used in the algorithm of the E-model, are listed in Table 3. It is strongly recommended to use these default values for all parameters that do not vary during planning calculation. If all parameters are set to the default values, the calculation results in a very high quality with a rating factor of *R* = 93.2. + +**Table 3 – Default values and permitted ranges for the parameters** + +| Parameter | Abbr. | Unit | Default value | Permitted range | Remark | +|-----------------------------------------|--------|-------|---------------|-----------------|--------------| +| Send loudness rating | SLR | dB | +8 | 0 ... +18 | (Note 1) | +| Receive loudness rating | RLR | dB | +2 | –5 ... +14 | (Note 1) | +| Sidetone masking rating | STMR | dB | 15 | 10 ... 20 | (Notes 2, 4) | +| Listener sidetone rating | LSTR | dB | 18 | 13 ... 23 | (Note 2) | +| D-Value of telephone, send side | Ds | – | 3 | –3 ... +3 | (Note 2) | +| D-Value of telephone, receive side | Dr | – | 3 | –3 ... +3 | (Note 2) | +| Talker echo loudness rating | TELR | dB | 65 | 5 ... 65 | | +| Weighted echo path loss | WEPL | dB | 110 | 5 ... 110 | | +| Mean one-way delay of the echo path | T | ms | 0 | 0 ... 500 | | +| Round-trip delay in a 4-wire loop | Tr | ms | 0 | 0 ... 1000 | | +| Absolute delay in echo-free connections | Ta | ms | 0 | 0 ... 500 | | +| Delay sensitivity | sT | – | 1 | 0.4 ... 1 | (Note 7) | +| Minimum perceivable delay | mT | ms | 100 | 20 ... 150 | (Note 7) | +| Number of quantization distortion units | qdu | – | 1 | 1 ... 14 | | +| Equipment impairment factor | Ie | – | 0 | 0 ... 40 | (Note 5) | +| Packet-loss robustness factor | Bpl | – | 4.3 | 4.3 ... 40 | (Notes 3, 5) | +| Random packet-loss probability | Ppl | % | 0 | 0 ... 20 | (Notes 3, 5) | +| Burst ratio | BurstR | – | 1 | 1 ... 8 | (Notes 3, 6) | +| Circuit noise referred to 0 dBr-point | Nc | dBm0p | –70 | –80 ... –40 | | +| Noise floor at the receive side | Nfor | dBmp | –64 | – | (Note 3) | +| Room noise at the send side | Ps | dB(A) | 35 | 35 ... 85 | | + +**Table 3 – Default values and permitted ranges for the parameters** + +| Parameter | Abbr. | Unit | Default value | Permitted range | Remark | +|--------------------------------|-------|-------|---------------|-----------------|--------| +| Room noise at the receive side | Pr | dB(A) | 35 | 35 ... 85 | | +| Advantage factor | A | – | 0 | 0 ... 20 | | + +NOTE 1 – Total values between microphone or receiver and 0 dBr-point. +NOTE 2 – Fixed relation: $LSTR = STMR + D$ . +NOTE 3 – Currently under study. +NOTE 4 – Equation 7-24 provides also predictions for $STMR > 20$ dB. However, such values can hardly be measured in a reliable way because the measurement device will mainly cover the acoustic coupling, and not the electrical one. +NOTE 5 – If $Ppl > 0\%$ , then the Bpl must match the codec, packet size and packet loss concealment (PLC) assumed. +NOTE 6 – E-model predictions for values of $BurstR > 2$ are only valid if the packet loss percentage is $Ppl < 2\%$ . +NOTE 7 – Only predefined settings are allowed for sT and mT, reflecting specific use cases, see main body of the Recommendation. + +The 2000 version of this Recommendation provided an enhanced version of the E-model algorithm (see Annex A). + +Due to the changes made in the 2000 version of this Recommendation, the resulting rating $R$ with all parameter values set to default has slightly changed (from $R = 94.2$ to $R = 93.2$ ). For practical planning purposes, however, this slight deviation should be considered insignificant. + +## Annex A + +### Conditions for using the E-model + +(This annex forms an integral part of this Recommendation.) + +NOTE – The assessment and enhancement of the E-model algorithm are for further study. New results will be included as soon as they become available. + +### A.1 Examples of conditions where caution must be exercised when using the E-model + +- *The overall level of equipment impairment factors* + +Some experimental investigations suggest that the general tendency of the equipment impairment factors is too pessimistic, so that a hidden security margin may be incorporated. + +- *The overall additivity property of the model* + +The E-model assumes that different kinds of impairments are additive on the scale of the transmission rating factor $R$ . This feature has not been checked to a satisfactory extent. More specifically, very few investigations are available regarding the interaction of low bit-rate codecs with other kinds of impairments, e.g., with room noise. Additionally, the order effects when tandeming several low bit-rate codecs remain uncertain. + +- *The coverage of talker sidetone* + +Some experiments show that the E-model disregards some masking effects occurring for talker sidetone, namely in conjunction with circuit noise, room noise at receive side and low delay talker echo ( $< 10$ ms). + +- *The advantage factor $A$* + +Up to now it has not been clarified under which conditions the given values for the advantage factor should be applied. It is expected that these values may depend for example on the user group, and that the absolute values will change in the long term. + +- *Derivation methodology for new equipment impairment factors* + +A new methodology for deriving equipment impairment factors from subjective listening quality tests has been adopted as [ITU-T P.833]. A new methodology for deriving equipment impairment factors from instrumental models such as [ITU-T P.863] has been adopted as [ITU-T P.834]. + +- *Predictions for different types of room noise and different frequency shapes in the communication channel, in the sidetone path and in the echo path* + +The E-model regards the effect of room noise only by means of an A-weighted level. The actual opinion on the speech communication quality may depend even on the type and disturbance of the environmental noise. The frequency characteristics of the communication channel, of the sidetone and of the echo path are not explicitly regarded by the E-model, but only implicitly by means of loudness ratings. However, they may affect the perceived transmission quality. + +### A.2 Conditions for which the performance of the E-model has been improved by updating from the earlier version + +#### – *The effect of room noise at send side* + +With the present enhanced E-model algorithm (2000 version), the Lombard effect (the fact that the speaker adapts his/her pronunciation and speaking level according to the noise environment) is no longer disregarded. This had, in the 1998 version, led to too pessimistic E-model predictions for high room noise levels $P_r$ . + +#### – *Predictions for quantizing distortion* + +In case of the 1998 version of the E-model, subjective test results for modulated noise reference unit (MNRU) reference conditions were very often more pessimistic than E-model predictions. The graphs in Figure A.1 have been derived from the 1998 version and the 2000 version of the E-model with all other parameters at their default values. + +![Figure A.1: Relation between the number of qdu and E-model rating R. The graph shows two curves: a dashed line for the 1998 version and a solid line for the 2000 version. The x-axis is 'Number of qdus' (1 to 15) and the y-axis is 'E-model rating R' (50 to 100). Both curves start at R ≈ 95 for 1 qdu. The 1998 curve (dashed) decreases to R ≈ 75 at 15 qdus. The 2000 curve (solid) decreases more sharply to R ≈ 65 at 15 qdus.](df7cb4ea9bd6c3f445f3e264773b125f_img.jpg) + +| Number of qdus | E-model rating $R$ (1998) | E-model rating $R$ (2000) | +|----------------|---------------------------|---------------------------| +| 1 | 95 | 95 | +| 3 | 94 | 90 | +| 5 | 92 | 85 | +| 7 | 88 | 78 | +| 9 | 83 | 72 | +| 11 | 78 | 67 | +| 13 | 74 | 63 | +| 15 | 70 | 59 | + +Figure A.1: Relation between the number of qdu and E-model rating R. The graph shows two curves: a dashed line for the 1998 version and a solid line for the 2000 version. The x-axis is 'Number of qdus' (1 to 15) and the y-axis is 'E-model rating R' (50 to 100). Both curves start at R ≈ 95 for 1 qdu. The 1998 curve (dashed) decreases to R ≈ 75 at 15 qdus. The 2000 curve (solid) decreases more sharply to R ≈ 65 at 15 qdus. + +**Figure A.1 – Relation between the number of qdu and E-model rating $R$** + +With respect to the slightly enhanced algorithm of the E-model, as given in this Recommendation, the relation between the parameter qdu and the E-model rating $R$ has been changed in order to align the algorithm better with the available subjective test results. + +#### – *Predictions for codec performance under random packet loss* + +Impairments due to codecs under packet-loss conditions were formerly handled by using codec-dependent tabulated equipment impairment factors for different packet-loss rates (in former versions of Appendix I of [ITU-T G.113]). As the aim is to reduce the amount of tabulated data for usage with the E-model, the possibilities of replacing tabulated $I_{es}$ for packet loss with corresponding equations were investigated. The approach selected leads to results very similar to those previously defined as $I_e$ for all codecs covered in the 2001 version of Appendix I of [ITU-T G.113]. + +#### – *Predictions for codec performance under dependent packet loss* + +With this version of the algorithm, loss distributions characterized by medium (short-term) loss dependencies (as opposed to long-term loss dependencies) have been integrated in the E-model. Up to now, the included approach has been evaluated only for the ITU-T G.729(A) codec, but is assumed to be applicable also to the ITU-T G.723.1 codec, and supposedly other codecs. Pending further verification, the algorithm should not be used with burst ratios higher than $BurstR = 2.0$ . The model can also be applied to burst ratios higher than 2.0, if the packet loss percentages $Ppl$ are lower than 2%. + +#### – *The effect of talker sidetone* + +Estimates of voice quality as a function of STMR for values $> 15$ dB, as provided by the 2002 version of this Recommendation, were too pessimistic and did not accurately match the results obtained in auditory tests. This proved to be especially important for telephones in North America that are typically specified to have nominal values of STMR from 16 to 18 dB. + +In the current revised version of the E-model algorithm, this observation is reflected by modifying the corresponding equation for $Ist$ as a function of sidetone ( $STMR$ ), see Equation 7-11. + +As mentioned in the main body of this Recommendation, talker echo may become more noticeable for quiet values of STMR. This is addressed by switching from *Idte* to *Idtes*, see Equation 7-24. To remain consistent, the talker echo threshold from $STMR > 15$ dB (2002 version of this Recommendation) was extended to $STMR > 20$ dB (the current version of this Recommendation). The modifications have no impact for values of $STMR < 15$ dB. Consequently, the quality prediction for the transmission rating factor $R$ for the default settings ( $STMR = 15$ dB) does not differ from that predicted by the previous model version (2002). The default value of $R$ is 93.2 for both the previous and the current versions. The situation is depicted in Figure A.2. + +![Figure A.2: Comparison of R versus STMR for the current and the previous versions of the E-model algorithm. The graph shows two curves: a solid blue line for the 2002 version and a dashed green line for the current version. The x-axis is STMR (dB) from 0 to 40, and the y-axis is R from 70 to 95. Both curves start at R ≈ 79 at 0 dB, rise to a peak of R ≈ 93.2 at 15 dB, and then diverge. The 2002 version drops sharply to R ≈ 70 at 30 dB, while the current version drops more gradually to R ≈ 75 at 40 dB.](3e0c2bf6c51c575d096c7fc95c1e8454_img.jpg) + +| STMR (dB) | 2002 version (R) | Current version (R) | +|-----------|------------------|---------------------| +| 0 | 79 | 79 | +| 5 | 88 | 88 | +| 10 | 93 | 93 | +| 15 | 93.2 | 93.2 | +| 20 | 85 | 93 | +| 25 | 75 | 88 | +| 30 | 70 | 83 | +| 35 | - | 78 | +| 40 | - | 75 | + +Figure A.2: Comparison of R versus STMR for the current and the previous versions of the E-model algorithm. The graph shows two curves: a solid blue line for the 2002 version and a dashed green line for the current version. The x-axis is STMR (dB) from 0 to 40, and the y-axis is R from 70 to 95. Both curves start at R ≈ 79 at 0 dB, rise to a peak of R ≈ 93.2 at 15 dB, and then diverge. The 2002 version drops sharply to R ≈ 70 at 30 dB, while the current version drops more gradually to R ≈ 75 at 40 dB. + +**Figure A.2 – Comparison of $R$ versus STMR for the current and the previous versions of the E-model algorithm** + +#### – *The effect of pure delay* + +Based on several conversation tests, it has been shown that even long delay values may not affect the perceived speech quality, that is, in terms of the attribution of the delay effect to the system. In such cases, the predictions by previous versions of the E-model may be more pessimistic than actual user opinion. As a consequence, in specific cases speech quality predictions may be sought that are better tailored to some less stringent delay requirements. + +As a consequence, in the current revised version of the E-model, the delay sensitivity $sT$ and minimum perceivable delay $mT$ have been introduced. With an appropriate choice of these two parameters, both default and less delay-sensitive calls can be addressed. It is advisable to use these new parameters carefully according to the expected delay class according to Table 1. + +## Annex B + +### Quality measures derived from the transmission rating factor $R$ + +(This annex forms an integral part of this Recommendation.) + +The transmission rating factor $R$ can lie in the range from 0 to 100, where $R = 0$ represents an extremely bad quality and $R = 100$ represents a very high quality. The E-model provides a statistical estimation of quality measures. The percentages for a judgement of good or better (GoB) or poor or worse (PoW) are obtained from the $R$ -factor by means of the Gaussian error function: + +$$E(x) = \frac{1}{\sqrt{2\pi}} \int_{-\infty}^x e^{-\frac{t^2}{2}} dt \quad (B-1)$$ + +The equations are: + +$$GoB = 100E\left(\frac{R - 60}{16}\right)\% \quad (B-2)$$ + +$$PoW = 100E\left(\frac{45 - R}{16}\right)\% \quad (B-3)$$ + +An estimated mean opinion score ( $MOS_{CQE}$ ) for the conversational situation in the scale 1-5 can be obtained from the $R$ -factor using the equations: + +$$\text{For } R < 0: \quad MOS_{CQE} = 1 \quad (B-4)$$ + +$$\text{For } 0 < R < 100: \quad MOS_{CQE} = 1 + 0.035R + R(R - 60)(100 - R)7 \cdot 10^{-6}$$ + +$$\text{For } R > 100: \quad MOS_{CQE} = 4.5$$ + +This equation can be inverted in the range $6.5 \leq R \leq 100$ to calculate $R$ from $MOS_{CQE}$ , see Appendix I. GoB, PoW and $MOS_{CQE}$ as functions of $R$ are depicted in Figures B.1 and B.2, respectively. + +![Figure B.1: A line graph showing Good or better (GoB) and poor or worse (PoW) as functions of rating factor R. The x-axis is R (0 to 100) and the y-axis is percentage (1 to 99). The PoW curve decreases from 100% at R=0 to 0% at R=100. The GoB curve increases from 0% at R=0 to 100% at R=100. The curves intersect at R=60, where both are approximately 50%.](1577abe02184da5a60ec8d469ddb439e_img.jpg) + +| R | PoW (%) | GoB (%) | +|-----|---------|---------| +| 0 | 100 | 0 | +| 20 | ~90 | ~10 | +| 40 | ~75 | ~25 | +| 60 | ~50 | ~50 | +| 80 | ~25 | ~75 | +| 100 | 0 | 100 | + +Figure B.1: A line graph showing Good or better (GoB) and poor or worse (PoW) as functions of rating factor R. The x-axis is R (0 to 100) and the y-axis is percentage (1 to 99). The PoW curve decreases from 100% at R=0 to 0% at R=100. The GoB curve increases from 0% at R=0 to 100% at R=100. The curves intersect at R=60, where both are approximately 50%. + +Figure B.1 – Good or better (GoB) and poor or worse (PoW) as functions of rating factor $R$ + +![Figure B.2: MOSCQE as function of rating factor R. The graph shows a curve on a grid where the x-axis is R (0 to 100) and the y-axis is MOS (1 to 5). The curve starts at (0, 1) and rises to approximately (100, 4.5).](60e9207be66a64332619bb4b667fe67b_img.jpg) + +The figure is a line graph showing the relationship between the rating factor $R$ and the Mean Opinion Score (MOS). The x-axis represents $R$ from 0 to 100 in increments of 20. The y-axis represents MOS from 1 to 5, with labels 'Bad 1', 'Poor 2', 'Fair 3', 'Good 4', and 'Excellent 5'. A smooth curve starts at the point (0, 1) and increases monotonically, ending at approximately (100, 4.5). The curve is concave down, indicating that the rate of increase in MOS decreases as $R$ increases. + +Figure B.2: MOSCQE as function of rating factor R. The graph shows a curve on a grid where the x-axis is R (0 to 100) and the y-axis is MOS (1 to 5). The curve starts at (0, 1) and rises to approximately (100, 4.5). + +**Figure B.2 – MOSCQE as function of rating factor $R$** + +In some cases, transmission planners may not be familiar with the use of quality measures such as the $R$ rating factor obtained from planning calculations, and thus provisional guidance for interpreting calculated $R$ factors for planning purposes is given in Table B.13. This table also contains equivalent transformed values of $R$ into estimated conversational MOSCQE, GoB and PoW. + +**Table B.1 – Provisional guide for the relation between $R$ -value and user satisfaction** + +| R-value
(lower limit) | MOSCQE
(lower limit) | GoB (%)
(lower limit) | PoW (%)
(upper limit) | User satisfaction | +|-----------------------------------------------|--------------------------------------------|----------------------------------|----------------------------------|-------------------------------| +| 90 | 4.34 | 97 | ~0 | Very satisfied | +| 80 | 4.03 | 89 | ~0 | Satisfied | +| 70 | 3.60 | 73 | 6 | Some users dissatisfied | +| 60 | 3.10 | 50 | 17 | Many users dissatisfied | +| 50 | 2.58 | 27 | 38 | Nearly all users dissatisfied | + +3 The source of Table B.1 is Table 1 of [ITU-T G.109]. + +## Appendix I + +### Calculation of $R$ from $MOS_{CQE}$ values + +(This appendix does not form an integral part of this Recommendation.) + +In the range $6.5 \leq R \leq 100$ , $R$ can be calculated from $MOS_{CQE}$ using the formula: + +$$R = \frac{20}{3} \left( 8 - \sqrt{226} \cos \left( h + \frac{\pi}{3} \right) \right) \quad (I-1)$$ + +with: + +$$h = \frac{1}{3} \arctan2 \left( 18566 - 6750 MOS_{CQE}, 15 \sqrt{-903522 + 1113960 MOS_{CQE} - 202500 MOS_{CQE}^2} \right) \quad (I-2)$$ + +and: + +$$\arctan2(x, y) = \begin{cases} \arctan\left(\frac{y}{x}\right) & \text{for } x \geq 0 \\ \pi - \arctan\left(\frac{y}{-x}\right) & \text{for } x < 0 \end{cases} \quad (I-3)$$ + +The function $\arctan2(x, y)$ is implemented in ANSI C as the function $\text{atan2}(y, x)$ . Users should note that the order of the two parameters differs in this case. + +## **Appendix II** + +### **Provisional impairment factor framework for wideband speech transmission** + +(This appendix does not form an integral part of this Recommendation.) + +The contents of this appendix have been moved to [ITU-T G.107.1]. + +## Appendix III + +### Reference implementation of the E-model in ITU-T G.107 + +(This appendix does not form an integral part of this Recommendation.) + +The reference implementation of the E-model is no longer provided in the traditional qbasic listing (which was provided in previous versions of this Recommendation), since it was no longer found to be appropriate. Therefore, the ITU-T provides a new implementation of the E-model in PHP4 scripting language. + +The associated electronic attachment (which is available free of charge on the ITU publications website at ) contains the following files in the Software folder: + +- General instructions: readme.txt +- PHP4 script: calc.php +- 3 required Java scripts: + - wz\_tooltip.js + - tip\_centerwindow.js + - tip\_followscroll.js +- Copyright notice + +In order to run this software on any server outside ITU, a licence must be obtained from the organization indicated in the software Copyright notice. + +However, the very same PHP4 script has been implemented on the ITU website, where everyone has the right to use that software from that web server, under their own responsibility and at their own risk, without limitation, subject to no particular conditions, no royalties are due, etc. No software copyright licence agreements are required for such usage. That tool is available here: + +## Appendix IV + +### Use of the E-model in conjunction with noise reduction or echo canceller systems in the network or the terminal equipment + +(This appendix does not form an integral part of this Recommendation.) + +Modern networks or terminals frequently contain devices for echo cancellation and/or noise reduction. Echo cancellers are expected to significantly reduce the echo and the amount of residual echo may be considered in the same way the standard E-model does, i.e., via the residual talker echo loudness rating *TELR* and the mean one-way delay *T* of the residual echo path. However, the echo attenuation may also vary over time (so-called "echo pumping"), and the cancellation process may lead to degradations of the transmitted speech signal. Degradations of the transmitted speech signal may also result from imperfect noise reduction, e.g., when parts of the speech spectrum are subtracted by the noise reduction algorithm. Such a degradation due to imperfect noise reduction is also not covered by the current version of the E-model. + +In order to assess these effects in a more elaborated way, it is proposed to go through all the steps of the following provisional procedure which apply to the given scenario (i.e., noise reduction, echo cancellation, or both), see also [b-Möller]: + +- 1) The residual noise resulting from imperfect background noise reduction may occur either during speech intervals or during pauses; parameters describing these two situations are defined in [b-ITU-T G.160], namely *SNRI* (the SNR improvement during speech in dB) and *TNLR* (the total noise level reduction in dB). It is proposed to use a weighting of half and half (corresponding to roughly 50% speech activity) for the speech and silence parts and change Equation 7-4 as follows: + +$$\begin{aligned} Nos &= Ps - SLR - Ds - 0.5(SNRI + TNLR) - 100 \\ &\quad + 0.004(Ps - OLR - Ds - 14)^2 \end{aligned} \quad (IV-1)$$ + +This amendment is meant to capture the effect of residual noise of the noise reduction mechanism. + +In the case that a non-white background noise is assumed, the factor *Ds* of Equation IV-1 might depend on the noise type used for its measurement; see the ITU-T Handbook on Telephonometry [b-ITU-T HB Teleph]. In that case, it is suggested to use noise of the same type as it is assumed to occur in the background. + +- 2) The effects of speech degradation from imperfect noise reduction can be captured by estimating via an additional equipment impairment factor *Ie,nr* reflecting the noise reduction equipment. Such an additional equipment impairment factor should ideally be derived with the help of auditory listening-only tests carried out in accordance with [b-ITU-T P.835]. As an alternative, the S-MOS scores might also be estimated with the objective model of [b-ETSI EG 202]. Provided that such S-MOS scores are available for (1) the connection of the noise-reduced case and (2) for a noise-free connection without the noise-reduction system applied, *Ie,nr* can be calculated as: + +$$Ie,nr = \min(R(S-MOS2) - R(S-MOS1), 0) \quad (IV-2)$$ + +In this equation, the transformation from S-MOS to *R* is performed using the relationship between MOS and *R* given in the E-model. The resulting *Ie,nr* scores are preferably normalized following the procedure of [ITU-T P.834]. + +- 3) The effects of residual echo are taken into account in the standard way of the E-model, i.e., via the talker-echo impairment factor *Idte*; the frequency-dependent attenuation of the residual echo path has to be used for the calculation of *TELR* at this stage. + +- 4) The effects of speech degradation from imperfect echo cancellation can be estimated via an additional equipment impairment factor $I_{e,ec}$ which is calculated with the help of the procedure of [ITU-T P.834], using the instrumental model of [ITU-T P.863]. The calculation is performed as in step 2 and it is also preferable to normalize the obtained raw $I_{e,ec}$ score with the help of the procedure of [ITU-T P.834]. + +Please note that [ITU-T P.863] is not intended to be used with talker echo as a test factor, so applying it to derive impairment factors for echo cancellers should be exercised with care. + +- 5) Both $I_{e,nr}$ and $I_{e,ec}$ are added to the effective equipment impairment factor $I_{e,eff}$ before calculating the overall transmission rating $R$ . +- 6) The effects of delay are captured in the usual way via $I_{dd}$ . + +The proposed methodology is only provisional, as it has not been thoroughly validated. However, it is assumed that it results in better estimations than by not considering the mentioned effects of noise reduction and echo canceller equipment. The following effects are not yet covered by the methodology and are thus for further study in ITU-T: + +- The effect of time-varying echo paths. +- The effects of variable background noise transmission due to the echo canceller. +- The reduction of the double-talk capability due to the echo canceller. +- The degradation resulting from the acoustic characteristics of the terminal to which noise reduction and/or echo cancellers might be integrated. + +# Bibliography + +- [b-ITU-T G.160] Recommendation ITU-T G.160 (2012), *Voice enhancement devices*. +- [b-ITU-T G.711] Recommendation ITU-T G.711 (1988), *Pulse code modulation (PCM) of voice frequencies*. +<> +- [b-ITU-T G.712] Recommendation ITU-T G.712 (2001), *Transmission performance characteristics of pulse code modulation channels*. +<> +- [b-ITU-T G.722] Recommendation ITU-T G.722 (2012), *7 kHz audio-coding within 64 kbit/s*. +<> +- [b-ITU-T G.723.1] Recommendation ITU-T G.723.1 (2006), *Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s*. +<> +- [b-ITU-T G.729] Recommendation ITU-T G.729 (2012), *Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP)*. +<> +- [b-ITU-T P.10] Recommendation ITU-T P.10/G.100 (2006), *Vocabulary for performance and quality of service*. +<> +- [b-ITU-T P.48] Recommendation ITU-T P.48 (1988), *Specification for an intermediate reference system*. +<> +- [b-ITU-T P.800] Recommendation ITU-T P.800 (1996), *Methods for subjective determination of transmission quality*. +<> +- [b-ITU-T P.835] Recommendation ITU-T P.835 (2003), *Subjective test methodology for evaluating speech communication systems that include noise suppression algorithm*. +<> +- [b-ITU-T P-Sup.3] ITU-T P-series Recommendations – Supplement 3 (1993), *Models for predicting transmission quality from objective measurements*. +<> +- [b-ETSI EG 202] ETSI EG 202 396-3 (2007), *Speech Quality Performance in the Presence of Background Noise – Part 3: Background Noise Transmission – Objective Test Methods*, European Telecommunications Standards Institute, Sophia Antipolis. +<[http://www.etsi.org/deliver/etsi\\_eg/202300\\_202399/20239603/01.03.01\\_60/eg\\_20239603v010301p.pdf](http://www.etsi.org/deliver/etsi_eg/202300_202399/20239603/01.03.01_60/eg_20239603v010301p.pdf)> +- [b-Möller] Möller, S., Kettler, F., Gierlich, H.-W., Poschen, S., Côté, N., Raake, A., Wältermann, M. (2011), *Extending the E-Model For Capturing Noise Reduction and Echo Canceller Impairments*, Journal of the Audio Engineering Society. + + + +## **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.107.1-201906-I_PDF-E/1d7527f4316cfe2d342b08d1653d1592_img.jpg b/marked/G/T-REC-G.107.1-201906-I_PDF-E/1d7527f4316cfe2d342b08d1653d1592_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..e833b57236e86b7d4a316962451f15c987da0559 --- /dev/null +++ b/marked/G/T-REC-G.107.1-201906-I_PDF-E/1d7527f4316cfe2d342b08d1653d1592_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:458648899db3b571932f7abfaebc00a85dcc4bf58d2b407601a08107f5f55fb0 +size 6997 diff --git a/marked/G/T-REC-G.107.1-201906-I_PDF-E/4e0ade2f41b66d5602160da5cc978274_img.jpg b/marked/G/T-REC-G.107.1-201906-I_PDF-E/4e0ade2f41b66d5602160da5cc978274_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..5a516e5313395cf7adebddc54510837e137368c8 --- /dev/null +++ b/marked/G/T-REC-G.107.1-201906-I_PDF-E/4e0ade2f41b66d5602160da5cc978274_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:4bbec00255150d58eb1467712bd0b5cc05766460716e0bf77588fd30b87e81d0 +size 103594 diff --git a/marked/G/T-REC-G.107.1-201906-I_PDF-E/5b4e774d63e0e0ed73801a9247755e5f_img.jpg b/marked/G/T-REC-G.107.1-201906-I_PDF-E/5b4e774d63e0e0ed73801a9247755e5f_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..42ee9ce309b3936ec291def5736cab310194c0bc --- /dev/null +++ b/marked/G/T-REC-G.107.1-201906-I_PDF-E/5b4e774d63e0e0ed73801a9247755e5f_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:72202839faea8332aeb69f00017dad53e62762a66d6f6451b12c96c03b6b14de +size 83760 diff --git a/marked/G/T-REC-G.108-199909-I_PDF-E/raw.md b/marked/G/T-REC-G.108-199909-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..a123725e258f9e45c2fa15f052e4d44556eef741 --- /dev/null +++ b/marked/G/T-REC-G.108-199909-I_PDF-E/raw.md @@ -0,0 +1,4144 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt striking through it, and the letters 'ITU' superimposed on the globe. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.108** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(09/99) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +International telephone connections and circuits – General +definitions + +--- + +**Application of the E-model: A planning guide** + +ITU-T Recommendation G.108 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| General definitions | G.100–G.109 | +| General Recommendations on the transmission quality for an entire international telephone connection | G.110–G.119 | +| General characteristics of national systems forming part of international connections | G.120–G.129 | +| General characteristics of the 4-wire chain formed by the international circuits and national extension circuits | G.130–G.139 | +| General characteristics of the 4-wire chain of international circuits; international transit | G.140–G.149 | +| General characteristics of international telephone circuits and national extension circuits | G.150–G.159 | +| Apparatus associated with long-distance telephone circuits | G.160–G.169 | +| Transmission plan aspects of special circuits and connections using the international telephone connection network | G.170–G.179 | +| Protection and restoration of transmission systems | G.180–G.189 | +| Software tools for transmission systems | G.190–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +*For further details, please refer to ITU-T List of Recommendations.* + +# **APPLICATION OF THE E-MODEL: A PLANNING GUIDE** + +## **Summary** + +The intent of this Recommendation is to demonstrate how the E-Model (described in Recommendation G.107 [3]) can be used in end-to-end transmission planning for a wide range of networks – local, national, multinational and transcontinental. + +## **Source** + +ITU-T Recommendation G.108 was prepared by ITU-T Study Group 12 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 30 September 1999. + +## **Keywords** + +E-Model, end-to-end, interconnection, Internet, network, PBX, planning, quality, speech, terminal, transmission. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2000 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +###### Page + +| | | | +|--------|-----------------------------------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 2 | +| 3 | Abbreviations..... | 6 | +| 4 | Definitions ..... | 8 | +| 4.1 | Private network ..... | 8 | +| 4.2 | Public network ..... | 8 | +| 4.3 | Quality aspects ..... | 9 | +| 4.4 | IP based network..... | 10 | +| 4.5 | Network elements ..... | 10 | +| 4.5.1 | Terminal elements ..... | 10 | +| 4.5.2 | Connection elements..... | 10 | +| 4.5.3 | Transmission elements ..... | 11 | +| 4.6 | Types of connections ..... | 11 | +| 5 | Reference configurations ..... | 12 | +| 6 | Basic planning principle – the impairment factor method in conjunction with the E-Model ..... | 15 | +| 7 | Parameters subject to planning and their limits ..... | 20 | +| 7.1 | Overall Loudness Rating..... | 20 | +| 7.2 | Echo ..... | 21 | +| 7.3 | Transmission time in echofree connections..... | 23 | +| 7.3.1 | General considerations..... | 23 | +| 7.3.2 | Considerations with respect to low bit-rate coders..... | 24 | +| 7.4 | Stability..... | 25 | +| 7.5 | Quantization distortion units..... | 26 | +| 7.6 | Equipment impairment factor ..... | 27 | +| 7.6.1 | Equipment impairment factor for codecs under conditions of packet loss.... | 28 | +| 7.7 | Delay variation versus time..... | 29 | +| 7.8 | Advantage factor A ..... | 30 | +| 7.9 | Limits at the public/private interface with respect to echo ..... | 31 | +| 7.9.1 | Public/private network interfaces – Europe..... | 31 | +| 7.9.2 | Public/private network interfaces – North America ..... | 31 | +| 7.10 | Parameters not directly subject to transmission planning..... | 32 | +| 7.10.1 | Frequency response..... | 32 | +| 7.10.2 | Circuit noise..... | 33 | +| 7.10.3 | Listener echo..... | 33 | + +| | Page | +|----------------------------------------------------------------------------------|-------------| +| 7.10.4 Sidetone ..... | 33 | +| 7.10.5 Room noise ..... | 33 | +| 7.10.6 Comfort noise, voice activity detection ..... | 34 | +| 7.10.7 Forward error correction ..... | 34 | +| 7.11 Synchronization ..... | 35 | +| 8 Calculation of end-to-end parameters ..... | 35 | +| 8.1 Overall loudness rating ..... | 36 | +| 8.2 Talker echo ..... | 38 | +| 8.2.1 Calculation for connections with one echo path ..... | 39 | +| 8.2.2 Calculation for connections with two echo paths ..... | 40 | +| 8.3 Transmission time in echofree connections ..... | 42 | +| 8.4 Quantization distortion units ..... | 42 | +| 8.5 Equipment impairment factor ..... | 43 | +| 8.6 Equipment impairment factor for codecs under conditions of packet loss ..... | 43 | +| 8.7 Delay variation versus time ..... | 43 | +| 9 Application of the E-Model in planning practice ..... | 43 | +| 9.1 General ..... | 43 | +| 9.2 Reference configurations ..... | 44 | +| 9.3 Handling of the input parameters ..... | 49 | +| 9.4 Interpretation of the results ..... | 50 | +| 9.5 Application of the E-Model for configurations with two echo paths ..... | 50 | +| 9.6 Use of computer programs ..... | 52 | +| 9.7 Default values and parameter ranges ..... | 53 | +| 10 Rules for the insertion of echo cancellers ..... | 55 | +| 10.1 Introduction ..... | 55 | +| 10.2 Characteristics of the echo cancellers ..... | 56 | +| 10.3 Limits for the application of echo cancellers ..... | 56 | +| 10.4 Determination of the location ..... | 57 | +| 10.5 Handling of echo cancellers in the E-Model ..... | 59 | +| 11 Realization of planning ..... | 60 | +| 11.1 General ..... | 60 | +| 11.2 Determination of the specific requirements ..... | 60 | +| 11.3 Definition of the reference configurations ..... | 61 | +| 11.4 Determination of the transmission parameters ..... | 62 | +| 11.5 End-to-end calculation with the E-Model ..... | 62 | +| 11.6 Analysis of the results ..... | 63 | + +| | | +|------------------------------------------------------------------------------|-----| +| Annex A – Transmission parameters for specific elements ..... | 64 | +| A.1   Elements in private and/or IP based networks ..... | 64 | +| A.1.1   Wired telephone sets..... | 64 | +| A.1.2   Wireless telephone sets (including cordless)..... | 66 | +| A.1.3   Switching equipment ..... | 67 | +| A.1.4   IP gateways ..... | 70 | +| A.1.5   Leased lines and tie trunks..... | 70 | +| A.1.6   Privately owned cable links ..... | 71 | +| A.1.7   Satellite links ..... | 72 | +| A.1.8   Low bit-rate coding..... | 72 | +| A.1.9   Packetized voice ..... | 73 | +| A.1.10  Echo cancellers ..... | 73 | +| A.2   Transmission parameters of public networks ..... | 75 | +| A.2.1   Loss..... | 77 | +| A.2.2   Mean one-way delay ..... | 77 | +| A.2.3   Echo loss..... | 77 | +| A.2.4   Insertion of echo cancellers ..... | 77 | +| A.2.5   Quantization distortion units (qdu)..... | 78 | +| A.2.6   Equipment impairment values (Ie) ..... | 78 | +| A.2.7   IP transmission related parameters ..... | 78 | +| A.3   Transmission parameter of the far-end termination..... | 78 | +| A.3.1   European far-end termination scenarios ..... | 79 | +| A.3.2   North American far-end termination scenarios ..... | 80 | +| Annex B – Planning examples ..... | 82 | +| B.1   Planning example for the European scenario..... | 82 | +| B.1.1   Description of the network and user's demand ..... | 82 | +| B.1.2   Definition of reference configurations..... | 83 | +| B.1.3   Determination of the transmission parameters ..... | 85 | +| B.1.4   End-to-end calculation with the E-Model..... | 88 | +| B.1.5   Analysis of the results..... | 97 | +| B.1.6   Application of echo cancellers..... | 97 | +| B.2   Planning example for the North American scenario..... | 100 | +| B.2.1   Definition of reference configurations..... | 100 | +| B.2.2   Determination of the transmission parameters ..... | 101 | +| B.2.3   End-to-end calculation with the E-Model..... | 101 | +| B.2.4   Reference configuration 1a (analogue set @ A, analogue set @ B)..... | 102 | +| B.2.5   Reference configuration 1b (digital set @ A, analogue set @ B)..... | 106 | +| B.2.6   Reference configuration 2 (portable connection scenario) ..... | 111 | + +| | Page | +|------------------------------------------------------------------------------------|-------------| +| B.2.7 Reference configuration 3a (analogue set @ B) ..... | 116 | +| B.2.8 Reference configuration 3b (digital set @ side B)..... | 120 | +| B.3 Planning example for IP transmission based scenarios ..... | 125 | +| Annex C – Echo control in specific applications ..... | 127 | +| C.1 Effective echo paths ..... | 127 | +| C.1.1 Echo path 1: for talker at the cordless telephone ..... | 127 | +| C.1.2 Echo path 2: for talker at the cordless telephone ..... | 127 | +| C.1.3 Echo path 3: for talker at the cordless telephone ..... | 127 | +| C.1.4 Echo path 4: for talker of the public network ..... | 128 | +| C.1.5 Echo path 5: for talker of the public network ..... | 128 | +| C.1.6 Echo path 6: for talker of the public network in an international call ..... | 128 | +| C.2 Operation of echo cancellers and soft suppressors ..... | 129 | +| C.3 Provision of echo control for the talker of the public network ..... | 130 | + +# Introduction + +Network transmission planning has, historically, been based on scenarios reflecting the then-current (mainly analogue) technology, and the components (terminals, switches, facilities) available to the network. + +Today, the global telephone network transmission environment is rapidly changing. Factors which are impacting this change are the no longer rigidly regulated network interconnections, liberalization of private network transmission parameters (particularly in Europe), increasing competition in the public networks, globalization of private networks, and the use of modern technology within private networks, driven by the customers' need for economical and flexible network solutions. + +In North America, this traditional approach to planning had to take into account the industry-prescribed loss plan for Multi-line Telecommunications Systems (e.g. for PBXs, as presented in [40]; this was the premise for developing a DPBX loss plan application guide [43]. Furthermore, this planning was constrained by the transmission plan, as well as interconnecting requirements, of the North American public switched telephone network (PSTN). + +Similarly, in Europe, planning had to consider not only the relevant private network parameters but also those of the main public networks in the different countries. Regulation policy in most European countries dictated rigid handling of network interconnections, in conjunction with sometimes very stringent limits, for the different transmission parameters for calls via the public network. + +Similar changes may apply to other countries or regions not mentioned before. + +In the ITU-T and the former CCITT, transmission planning had been based on the allocation of single parameter limits to individual sections of an international connection, thereby not considering other interconnecting networks, e.g. private networks or even the Internet. + +The traditional transmission planning methodologies and documents are no longer flexible enough to account for all these new factors. For modern transmission planning, the following issues have to be considered: + +- a) Multinational networks (especially private networks) are becoming common and require planning which takes into account regional differences in loss plan requirements (if there are any) and inter-network transmission plans. +- b) Due to the liberalization of the telecommunication markets (in Europe) there are no longer laid down ranges of values for transmission parameters by regulation. +- c) The changing scenario in the public network operator domain is impacting transmission performance. +- d) Planning of private networks is more complex than single PBX-configurations, therefore sufficient (tutorial) information about the planning, and calculation, methods needs to be provided. +- e) The Recommendation should be applicable to the use of new technology within the networks under consideration, including wireless (cordless or mobile) sections, transmission of packetized voice, etc. +- f) The Recommendation should provide sufficient planning methods and contain all the necessary information and tools which will enable the planner to design the network transmission plan such as to keep the resulting speech transmission quality for all possible end-to-end connections within expected limits. +- g) Greater flexibility in allocation of transmission parameters and provisions with more allowance for network transmission parameters than in earlier guidelines, standards, or regulations is necessary. +- h) The guidelines and planning examples of this Recommendation are based on the use of the E-Model as described in Recommendation G.107 [3]. + +All these issues mentioned above need to be taken into account. One new main aspect is that the planner has to consider that the allocation of transmission parameters has become very flexible. Due to the liberalization of the telecommunication markets there are not any longer rigid constrained allowed ranges of values for the transmission parameters within the networks under consideration. The use of new technology and the application of new services has become quite common in the different networks. So the planner has to care of various effects caused by the use of different technology in an environment of interconnected networks. + +The guidelines and principles in this Recommendation reflect this flexibility, particularly in the planning examples, where it is shown how the allocation and selection of parameters is applied in optimizing the speech transmission quality for various connection scenarios. + +It is a key feature of this Recommendation, to give guidance and tutorial information to the planner. The aim is to enable the planner to develop a transmission plan allowing to predict the resulting end-to-end speech transmission quality of voice telephony connection. + +The guidelines and principles in this Recommendation are based on the use of the E-Model which is a useful tool to estimate the combined effects of various transmission parameters. It is recommended to use the E-Model as a transmission planning tool for end-to-end intra-network connections (connection between two terminals of the same network) and inter-network connections (connection between two terminals of different networks). By using the E-Model the planner is enabled to lay down adequate ranges of values for the different transmission parameters. + +Furthermore, this Recommendation should enable the planner not only to ensure that absolute limits for various transmission parameters are not exceeded for any intra- or inter-network connection, but also to obtain an estimate of the expected speech transmission quality as perceived by the average user (in terms of E-Model Rating R, Mean Opinion Score or percentage Good-or-Better and Poor-or-Worse) for the investigated configuration. + +# **APPLICATION OF THE E-MODEL: A PLANNING GUIDE** + +*(Geneva, 1999)* + +# **1 Scope** + +This Recommendation applies to transmission planning of speech transmission quality for end-to-end intra- and inter-network connections. It should be considered as a tutorial and illustration for the planning of networks with respect to the speech transmission quality of narrow-band 3.1 kHz real time telephony via handsets. Networks designed according to this Recommendation will also provide sufficiently high speech quality for the transmission of announcements and stored speech. + +The guidelines and principles in this Recommendation are based on the use of the E-Model. Estimates of the perceived speech transmission quality calculated with the E-Model are only applicable to end-to-end connections, offering narrow-band 3.1 kHz real time telephony via handsets. + +The transmission of non-voice signals such as Fax and Modem transmission and wholly digital data transmission is beyond the scope of this Recommendation. + +This Recommendation does not address the following issues: + +- who owns and runs the network; +- who is responsible for end-to-end transmission quality; +- to whom services are provided. + +One application of this Recommendation is to medium and large private networks consisting of several interconnected MLTS. The terms "corporate network" or "enterprise network" are sometimes used to describe a large private network; in some countries these terms are used in a legal sense for a group of interconnected private networks. From the point of view of transmission planning, there is no difference between a large private network and several smaller interconnected networks. Therefore, only the term "private network" will be used in this Recommendation. + +The Recommendation addresses, as examples, only scenarios where the network under consideration, e.g. a "private network" functions as a terminating network (one to which terminal equipment is connected). Scenarios wherein a network provides transit connections between other networks are not considered. + +Notwithstanding these limitations, it is recommended to apply the principles described, and information given, in this Recommendation to other end-to-end connections supporting narrow-band 3.1 kHz real time telephony via handsets as well. This Recommendation can be applied to all kinds of intra- or inter-network connections. It is recommended to use these principles for the planning of end-to-end connections regardless of the number of public or private networks involved, or the specific configuration they are interconnected. + +For the purposes of this Recommendation, there are no restrictions on the network with respect to size, configuration, hierarchy, technology used, nor on the components of the network. The transmission media may be cable, fibre or radio. + +The discussion in this Recommendation addresses primarily the use of digital interfaces (almost universal in Europe) between the networks under consideration, but also allows for analogue network interconnections. The signal transmission within the network under consideration may be analogue or digital. + +The prevalence of digital signal transmission media and digital signal handling in switching equipment impacts the relative importance of various transmission parameters to be considered in planning. For the benefit of simplification, parameters which cause only minor impairments in a digital environment, such as the frequency shape of cables, circuit noise, crosstalk, variations of loss with level or time etc., are not subject to the planning guidelines in this Recommendation. More emphasis is placed on parameters such as echo, delay, signal processing equipment impairments, and acoustic characteristics of terminals. + +This Recommendation does not contain transmission requirements for specific network elements such as telephone sets, switching equipment (e.g. PBXs) or transmission equipment. It is assumed that the design of such elements conforms to applicable Recommendations, regional standards or regulations. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.100 (1993), *Definitions used in Recommendations on general characteristics of international telephone connections and circuits.* +- [2] ITU-T Recommendation G.101 (1996), *The transmission plan.* +- [3] ITU-T Recommendation G.107 (1998), *The E-Model, a computational model for use in transmission planning.* +- [4] ITU-T Recommendation G.109 (1999), *Definition of categories of speech transmission quality.* +- [5] ITU-T Recommendation G.113 Appendix I (1999), *Transmission impairments – Appendix I: Provisional planning values for the equipment impairment factor Ie.* +- [6] ITU-T Recommendation G.114 (1996), *One-way transmission time.* +- [7] ITU-T Recommendation G.122 (1993), *Influence of national systems on stability and talker echo in international connections.* +- [8] ITU-T Recommendation G.126 (1993), *Listener echo in telephone networks.* +- [9] ITU-T Recommendation G.131 (1996), *Control of talker echo.* +- [10] ITU-T Recommendation G.164 (1988), *Echo suppressors.* +- [11] ITU-T Recommendation G.165 (1993), *Echo cancellers.* +- [12] ITU-T Recommendation G.168 (1997), *Digital network echo cancellers.* +- [13] ITU-T Recommendation G.177 (1999), *Transmission planning for voiceband services over hybrid Internet/PSTN connections.* +- [14] ITU-T Series G-series Recommendations Supplement 31 to Section 1 (1993), *Principles of determining an impedance strategy for the local network.* +- [15] ITU-T Recommendation G.711 (1988), *Pulse code modulation (PCM) of voice frequencies.* +- [16] ITU-T Recommendation G.721 (1988), *32 kbit/s Adaptive differential pulse code modulation (ADPCM).* + +- [17] ITU-T Recommendation G.723.1 (1996), *Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s.* +- [18] ITU-T Recommendation G.726 (1990), *40, 32, 24, 16 kbit/s adaptive differential pulse code modulation (ADPCM).* +- [19] ITU-T Recommendation G.727 (1990), *5-, 4-, 3- and 2-bits/sample embedded adaptive differential pulse code modulation (ADPCM).* +- [20] ITU-T Recommendation G.728 (1992), *Coding of speech at 16 kbit/s using low-delay code excited linear prediction.* +- [21] ITU-T Recommendation G.728 Annex H (1997), *Variable bit rate LD-CELP operation mainly for DCME at rates less than 16 kbit/s.* +- [22] ITU-T Recommendation G.729 (1996), *Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear-prediction.* +- [23] ITU-T Recommendation G.729 Annex D (1998), *6.4 kbit/s CS-ACELP speech coding algorithm.* +- [24] ITU-T Recommendation G.729 Annex E (1998), *11.8 kbit/s CS-ACELP speech coding algorithm.* +- [25] ITU-T Recommendation G.822 (1988), *Controlled slip rate objectives on an international digital connection.* +- [26] ITU-T Recommendation H.323 (1998), *Packet based multimedia communications systems.* +- [27] ITU-T Recommendation P.310 (1996), *Transmission characteristics for telephone band (300-3400 Hz) digital telephones.* +- [28] ITU-T Recommendation P.50 (1993), *Artificial voices.* +- [29] ITU-T Recommendation P.79 (1993), *Calculation of loudness ratings for telephone sets.* +- [30] ITU-T Recommendation P.800 (1996), *Methods for subjective determination of transmission quality.* +- [31] ITU-T Recommendation P.82 (1984), *Method for evaluation of service from the standpoint of speech transmission quality.* +- [32] ITU-T Recommendation P.830 (1996), *Subjective performance assessment of telephone-band and wideband digital codecs.* +- [33] ITU-T Recommendation P.84 (1993), *Subjective listening test method for evaluating digital circuit multiplication and packetized voice systems.* +- [34] ITU-T Recommendation P.561 (1996), *In-service, non-intrusive measurement device – Voice service measurements.* +- [35] ITU-T Recommendation P.861 (1998), *Objective quality measurement of telephone-band (300-3400 Hz) speech codecs.* +- [36] ITU-T Recommendation Q.551 (1996), *Transmission characteristics of digital exchanges.* +- [37] ITU-T Recommendation Q.552 (1996), *Transmission characteristics at 2-wire analogue interfaces of digital exchanges.* +- [38] ITU-T Recommendation Q.553 (1996), *Transmission characteristics at 4-wire analogue interfaces of digital exchanges.* +- [39] ITU-T Recommendation Q.554 (1996), *Transmission characteristics at digital interfaces of digital exchanges.* + +- [40] TIA/EIA-464-B (1996), *Requirements for Private Branch Exchange (PBX) Switching Equipment.* +- [41] TIA/EIA-470-B (1997), *Telecommunications – Telephone Terminal Equipment – Performance and Compatibility Requirements for Telephone sets with Loop Signalling.* +- [42] TIA/EIA-579-A (1998), *Telecommunications Telephone Terminal Equipment Transmission Requirements for Digital Wireline Telephones.* +- [43] TIA/EIA TSB32-A (1998), *Overall Transmission Plan Aspects for Telephony in a Private Network.* +- [44] ANSI T1.508 (1998), *Telecommunications – Network Performance – Loss Plan for Evolving Digital Networks.* +- [45] EIA/TIA/IS-54-B (1992), *Cellular System Dual Mode Mobile-Station Base-Station Compatibility Standard* (upgraded to ANSI/TIA/EIA-627 in June 1996). +- [46] TIA/EIA-96-C (1998), *Speech Service Option Standard for Wideband Spread Spectrum Systems.* +- [47] TIA/EIA/IS-127 (1997), *Enhanced Variable Rate Codec, Speech Service Option 3 for Wideband Spread Spectrum Digital Systems.* +- [48] TIA/EIA/IS-641-A (1996), *TDMA Cellular/PCS-Radio Interface – Enhanced Full-Rate Speech Codec.* +- [49] ETSI TBR 008 ed.1 (1994), *Integrated Services Digital Network (ISDN); Telephony 3.1 kHz teleservice; Attachment requirements for handset terminals.* +- [50] ETSI TBR 010 ed.2 (1997), *Digital Enhanced Cordless Telecommunications (DECT); General terminal attachment requirements: Telephony applications.* +- [51] ETSI EG 201 377-1 V1.1.1 (1999), *Speech Processing, Transmission and Quality Aspects (STQ); Specification and measurement of speech transmission quality; Part 1: Introduction to objective comparison measurement methods for one-way speech quality across networks.* +- [52] ETSI ES 201 168 V1.1.1 (1998), *Corporate telecommunication Networks (CN); Transmission characteristics of digital Private Branch eXchanges (PBXs).* +- [53] ETSI EN 300 175-8 V1.4.2 (1999), *Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 8: Speech Coding and Transmission.* +- [54] ETSI ETS 300 283 ed.1 (1994): *Business TeleCommunications (BTC); Planning of loudness rating and echo values for private networks digitally connected to the public network.* +- [55] ETSI: EN 300 462-series (1998), *Transmission and Multiplexing (TM); Generic requirements for synchronization networks.* +- [56] For the purposes of this Recommendation the following standards should be considered together as a package: + - ETSI EN 300 961 V7.0.2 (1999), *Digital cellular telecommunications system (Phase 2+); Full rate speech; Transcoding (GSM 06.10 version 7.0.2 Release 1998).* + - ETSI EN 300 962 V7.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Full rate speech; Substitution and muting of lost frames for full rate speech channels (GSM 06.11 version 7.0.1 Release 1998).* + - ETSI EN 300 963 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Full rate speech; Comfort noise aspect for full rate speech traffic channels (GSM 06.12 version 6.0.1 Release 1997).* + +ETSI EN 300 964 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Full rate speech; Discontinuous Transmission (DTX) for full rate speech traffic channels* (GSM 06.31 version 6.0.1 Release 1997). + +ETSI EN 300 965 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Full rate speech; Voice Activity Detector (VAD) for full rate speech traffic channels* (GSM 06.32 version 6.0.1 Release 1997). + +- [57] For the purposes of this Recommendation the following standards should be considered together as a package: + +ETSI EN 300 969 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Half rate speech; Half rate speech transcoding* (GSM 06.20 version 6.0.1 Release 1997). + +ETSI EN 300 970 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Half rate speech; Substitution and muting of lost frames for half rate speech traffic channels* (GSM 06.21 version 6.0.1 Release 1997). + +ETSI EN 300 971 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Half rate speech; Comfort noise aspects for the half rate speech traffic channels* (GSM 06.22 version 6.0.1 Release 1997). + +ETSI EN 300 972 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Half rate speech; Discontinuous Transmission (DTX) for half rate speech traffic channels* (GSM 06.41 version 6.0.1 Release 1997). + +ETSI EN 300 973 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Half rate speech; Voice Activity Detector (VAD) for half rate speech traffic channels* (GSM 06.42 version 6.0.1 Release 1997). + +- [58] For the purposes of this Recommendation the following standards should be considered together as a package: + +ETSI EN 300 726 V7.0.2 (1999), *Digital cellular telecommunications system (Phase 2+); Enhanced Full Rate (EFR) speech transcoding* (GSM 06.60 version 7.0.2 Release 1998). + +ETSI EN 300 727 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Substitution and muting of lost frames for Enhanced Full Rate (EFR) speech traffic channels* (GSM 06.61 version 6.0.1 Release 1997). + +ETSI EN 300 728 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Comfort noise aspects for Enhanced Full Rate (EFR) speech traffic channels* (GSM 06.62 version 6.0.1 Release 1997). + +ETSI EN 300 729 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Discontinuous Transmission (DTX) for Enhanced Full Rate (EFR) speech traffic channels* (GSM 06.81 version 6.0.1 Release 1997). + +ETSI EN 300 730 V6.0.1 (1999), *Digital cellular telecommunications system (Phase 2+); Voice Activity Detector (VAD) for Enhanced Full Rate (EFR) speech traffic channels* (GSM 06.82 version 6.0.1 Release 1997). + +- [59] ETSI ETR 250 ed.1 (1996), *Transmission and Multiplexing (TM); Speech communication quality from mouth to ear for 3.1 kHz handset telephony across networks*. + +- [60] ETSI ETR 275 ed.1 (1996), *Transmission and Multiplexing (TM); Considerations on transmission delay and transmission delay values for components on connections supporting speech communications over evolving digital networks*. + +- [61] ISO/IEC 11573:1994, *Information technology – Telecommunications and information exchange between systems – Synchronization methods and technical requirements for Private Integrated Services Networks*. + +[62] ARIB: RCR STD-27 H, Fascicle 1 (Revision H, February 2 1999), *Personal Digital Cellular Telecommunication System ARIB Standard*. + +# 3 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|----------|--------------------------------------------------------------| +| ACELP | Algebraic Code-Excited Linear Prediction | +| ADPCM | Adaptive Differential Pulse Code Modulation | +| ATM | Asynchronous Transfer Mode | +| CDMA | Code Division Multiple Access | +| CLR | Circuit Loudness Rating | +| CNG | Comfort Noise Generator | +| CRE | Corrected Reference Equivalent | +| CS-ACELP | Conjugate Structure Algebraic Code-Excited Linear Prediction | +| DAL | Digital Access Line | +| DCME | Digital Circuit Multiplication Equipment | +| DECT | Digital Enhanced Cordless Telecommunication | +| DPBX | Digital PBX | +| EC | Echo Canceller | +| ECD | Echo Control Device | +| EFR | Enhanced Full Rate Codec | +| EL | Echo Loss | +| ELE | Echo Loss Enhancement | +| ERLE | Echo Return Loss Enhancement | +| ERP | Ear Reference Point | +| ETSI | European Telecommunications Standards Institute | +| FDM | Frequency Division Multiplex | +| FEC | Forward Error Correction | +| GoB | Good or Better | +| GSM | Global System for Mobile communications | +| IC | Interexchange Carrier | +| ICP | International Connection Point | +| ICS | ISDN Compatible Station | +| INMD | In-service Non-intrusive Measurement Device | +| IP | Internet Protocol | +| ISDN | Integrated Services Digital Network | +| IST | Integrated Services Trunk | +| ITU | International Telecommunication Union | + +| | | +|---------|-------------------------------------------------| +| ITU-T | ITU Telecommunication Standardization Sector | +| IWF | InterWorking Function | +| KTS | Key Telephone System | +| LAN | Local Area Network | +| LD-CELP | Low-Delay Code-Excited Linear Prediction | +| LEC | Local Exchange Carrier | +| LELR | Listener Echo Loudness Rating | +| LSTR | Listener Sidetone Masking Rating | +| MLTS | Multi-line Telecommunications System | +| MOS | Mean Opinion Score | +| MRP | Mouth Reference Point | +| N.A. | North America(n) | +| NCP | Network Connection Point(s) | +| NLP | Non-Linear Processor | +| OLL | Open-Loop Loss | +| OLR | Overall Loudness Rating | +| ONS | On-Premises Station | +| OREM | Objective Reference Equivalent Measurement | +| PACS | Personal Access Communications System | +| PBX | Private Branch Exchange | +| PCI | Personal Communications Interface | +| PCM | Pulse Code Modulation | +| PoW | Poor or Worse | +| PSTN | Public Switched Telephone Network | +| PWT | Personal Wireless Telecommunications | +| qdu | Quantization distortion unit(s) | +| RLR | Receive Loudness Rating | +| RPE-LTP | Residual Pulse Excitation – Long Term Predictor | +| RTP | Real Time Protocol | +| SLR | Send Loudness Rating | +| SS | Soft Suppressor | +| STMR | Sidetone Masking Rating | +| TBRL | Terminal Balance Return Loss | +| TCLw | Terminal Coupling Loss (weighted) | +| TCP | Transmission Control Protocol | +| TDM | Time Division Multiplex | +| TDMA | Time Division Multiple Access | + +| | | +|-------|-----------------------------------------| +| TELR | Talker Echo Loudness Rating | +| TIA | Telecommunications Industry Association | +| UDP | User Data Protocol | +| UPCM | Uniform PCM | +| VAD | Voice Activity Detection | +| VNL | Via Net Loss | +| VPN | Virtual Private Network | +| VSELP | Vector Sum Excited Linear Prediction | +| WAN | Wide Area Network | +| WEPL | Weighted Echo Path Loss | +| WUPE | Wireless User Premises Equipment | + +# 4 Definitions + +This Recommendation defines the following terms: + +## 4.1 Private network + +In this Recommendation, the term "private network" is used to describe a network which provides features only to a restricted user group in contrast to the public network (PSTN) available to the general public. In general, a private network is a terminating network and consists of several interconnected nodes (i.e. PBXs), with interconnections to other (mainly public) networks. + +A private network is characterized as follows: + +- 1) It consists normally of more than one element of switching equipment (PBX or Key Telephone System KTS), connected via tie trunks or leased lines or via a Virtual Private Network (VPN). Network functionality is independent of its structure and hierarchy. Switching equipment and links can be either analogue or digital. +- 2) It provides switching functions and all other features only to a single customer or to a group of customers, and is not accessible to the general public. +- 3) It is not limited by geographical size or to a specific national area or region. +- 4) It has no limitation with regard to the number of extensions and access points to other networks. + +## 4.2 Public network + +The term "public network" is used in this Recommendation for any network providing transmission and switching functions as well as features which are available to the general public, not restricted to a specific user group. In this context, the word "public" does not imply any relation to the legal status of the network operator. + +In some cases, a public network may provide a limited set of features only. In a competitive environment, a public network may be restricted to serve a limited number of customers, or restricted to specific features or functions. Generally, public networks provide access points to other networks or terminals only within a specific geographical area. + +From the point of view of an end-to-end connection, a public network can function either as a "transit network" (a link between two other networks) or as a combination of "transit and terminating network" in case where the public network provides connections to terminal equipment such as + +telephone sets, or PBXs. In North America, Interexchange Carriers (IC) generally function as transit networks while the functions of a transit- and terminating-network are assigned to Local Exchange Carriers (LEC). + +## 4.3 Quality aspects + +Previous planning methods for terminating networks in general were usually based on limit values for the different transmission parameters between the telephone set (acoustic interface) and the interface to another, mainly public, network. This means that, only the section within the private network, as part of a full connection formed by the different network elements between a human mouth/ear and an electrical interface, was considered. + +However, the perception of speech transmission quality during a telephone conversation is primarily a "subjective" judgement. The concept of "quality" may not be considered as a unique discrete quantity, but may vary, depending on the user's expectation of sufficient "speech transmission quality" for a 3.1 kHz telephony call for the terminal mode (e.g. handset) as well as the particular service (e.g. wireless). With respect to transmission planning, the planning method and the necessary calculations should be based on an end-to-end consideration between one human's mouth and another human's ear. + +For the judgement of the quality in a given configuration, and the performance of "subjective tests", several methods are in use and are described in different Recommendations (e.g. Recommendations P.800 [30], P.82 [31], P.830 [32] and P.84 [33]). One of the most common methods is to perform laboratory tests (e.g. "listening only tests"), wherein the test subjects are requested to classify the perceived quality into categories. For example, a "quality rating" can be defined according to the following 5-grade scale: + +| Quality | Score | +|-----------|-------| +| Excellent | 5 | +| Good | 4 | +| Fair | 3 | +| Poor | 2 | +| Bad | 1 | + +The scores are used to calculate the average value of the judgement of several test subjects for the same test configuration. The result is the so-called "Mean Opinion Score" MOS which may, theoretically, range between 1 and 5. An assessment about the speech transmission quality can also be obtained by calculating the percentage of all test persons rating the Configuration as "good or better" or as "poor or worse". For a given connection these results are expressed as "Percentage Good or Better" (%GoB) and "Percentage Poor or Worse" (%PoW). + +In existing networks, public and private network providers may also use various methods to control and **monitor** the "Quality of Service" with respect to speech transmission quality. This can be done: + +- subjectively by customer interviews according to Recommendation P.800 [30]; +- via an objective method using test equipment referred to as an "In-service Non-intrusive Measurement Device" (INMD) according to Recommendation P.561 [34]; +- by objective measurement devices according to Recommendation P.861 [35] – Note however, that a process of refinement is underway in ITU-T Study Group 12. + +However, those methods as described in [51] are not applicable for the **planning** of networks. + +The main task during planning of networks is the collection of the necessary information on the various network components in the configuration investigated and their contribution of transmission impairments that impact the end-to-end connection speech transmission quality. To assist the planner, computational models are available which, with the pertinent input data, yield a calculated value for the E-Model Rating R and other quality measures, such as MOS, %GoB and %PoW. + +One of those tools is the "**E-Model**" which is recommended to be used for planning purposes of end-to-end 3.1 kHz handset telephony connections. For more information about the E-Model, see clause 6 in conjunction with Recommendation G.107 [3] and [59]. + +## 4.4 IP based network + +IP based networks may appear with distinct realizations which can be classified as follows: + +- managed and/or engineered private Enterprises Intranets (LANs); +- Service Provider domains (WANs); +- the public Internet (concatenated WANs); +- or a combination thereof. + +They consist of internal routers and edge routers (e.g. between LAN and WAN) which are establishing network links between the Interworking Functions (IWFs), so-called gateways, (e.g. to the PSTN) and the IP terminals (e.g. according to Recommendation H.323 [26]). + +IP based networks are relying on the Internet Protocol (IP) and provide for packet-based transport of data. Thus, a digitalized speech signal applied to the input of an Interworking Function (IWF) will be assembled to small packets. These packets then consist of an IP header which in general contains the following data: + +- destination address; +- other transport related information; +- headers of other protocols for transmission, real time, etc. (e.g. TCP, UDP, RTP); +- and of a small time segment of the speech signal. + +Finally, at the output of another IWF the speech segments will be decomposed to a continuous digital speech signal again. Alternatively, the packetizing as well as the decomposition of the speech signal can be provided by a terminal according to Recommendation H.323 [26] instead of the IWF. + +## 4.5 Network elements + +All components which constitute an end-to-end connection should be categorized into three main groups: terminal elements, connection elements and transmission elements. + +### 4.5.1 Terminal elements + +With respect to speech transmission, terminal elements are all types of telephone sets, digital or analogue, wired, cordless, or mobile, including the acoustical interfaces to the user's mouth and ear. These components are characterized by their Send Loudness Rating (SLR) and Receive Loudness Rating (RLR) which contribute to the Overall Loudness Rating (OLR) of a connection. Other terminal element parameters, such as the SideTone Masking Rating (STMR), the Listener SideTone Rating (LSTR), the design of the handset (D-Factor), the frequency response in send and receive directions and the noise floor, also contribute to the end-to-end connection rating of speech transmission quality. In case of wireless or IP based systems, additional distortions and delay may be added, depending on the coding and modulation algorithms used in such interfaces. + +### 4.5.2 Connection elements + +Connection elements are all types of switching equipment, such as local PBXs (for the direct connection of terminal elements) and transit PBXs in networks. Connection elements may use + +analogue or digital switching or packet based technology. The main impairment contributions of analogue systems are loss and noise. Digital switching systems contribute to the end-to-end delay, due to signal processing, and also to the amount of quantization distortion associated with digital pads and code conversion. Packet based routers contribute, in addition, with delay variation versus time and packet loss. Where 4-wire to 2-wire conversions take place within or between switching equipment interfaces, signal reflections contribute to impairments as a source for echo effects. + +### 4.5.3 Transmission elements + +Transmission elements are all kinds of media used as the facility between connection elements and between connection elements and terminal elements. The physical media of these elements may be metallic (copper), fibre-optics or radio. The signal form is either analogue or digital. Impairments associated with analogue signal transmission include propagation time (generally proportional to distance), loss, frequency response and noise (mainly due to longitudinal interference). + +For planning purposes, impairments due to frequency response and noise can usually be neglected for short and medium line lengths. + +For digital transmission elements, the main transmission impairment is caused by the propagation time via metallic, optic, and radio media. For wireless sections, additional delay is introduced, depending on the coding and modulation algorithm used. Where the transmission element includes analogue-to-digital conversion, loss and distortion are additional impairment factors. + +Multiplexing is generally used to transport several channels via one single physical media. A variety of multiplexing systems are in use in the existing networks: + +- Time Division Multiplex (TDM). +- Digital Circuit Multiplication Equipment (DCME). +- Packet Based Facilities: + - connection oriented (ATM); + - connectionless (Ethernet, IP). + +In digital transmission elements, systems use either 64 kbit/s Pulse Code Modulation (PCM) of Recommendation G.711 [15], or one of the more recently introduced compression techniques based on low bit-rate codecs. Major influence to the transmission quality of these systems may be caused by additional distortions in terms of qdu, or Equipment Impairment Factor (Ie), and by additional mean one-way delay. + +## 4.6 Types of connections + +For some networks, impairment allocation may be possible by taking into account the mix of connection types. For example, private networks may provide mainly internal connections, or may route a preponderance of calls destined for a public network terminal via private network facilities to a local PSTN switch near the destination ("tail-end hop-off"). Depending on the business of the private network user, the predominance of incoming and outgoing calls may be originated or terminated only within a local calling area. It may also be feasible to segregate calls between internal connections (between two terminal elements of the same private network), and external connections via a public network, which can be further divided into "local calls" for connections in the local area only, "national long distance calls" and "international calls." + +It should be noted that "predominance", in this context, is interpreted as an amount of connections, e.g. within the local area, of more than 95%. Consideration of the connection type mix into planning enables the planner, wherever this is possible, to extend the usually small allowance for specific parameters (e.g. transmission time) within the network under consideration, resulting in a more economical design of the network. + +# 5 Reference configurations + +The aim of reference configurations in transmission planning is to obtain an overview of the considered connection and to simplify the identification of all terminal-, connection- and transmission elements which contribute impairments to the end-to-end transmission performance. + +Due to the variety of hierarchy, structure, routing, number and types of network elements in a network, each investigated connection will result in a different reference configuration. Therefore, it is not possible to create a single generic configuration for the whole task of network planning. The following Figures should only be considered as examples, used mainly for definitions in this Recommendation. One main task in planning is to identify the type of interconnection between the network under consideration and other networks. Figure 1 shows a basic configuration, assuming a digital interface between the networks. + +![Diagram of basic configuration for the interconnection between private and public network. It shows two private network paths on the left connecting to a public network on the right via interfaces T_T and T_L. The public network includes a local exchange, a toll exchange, and an international switching center leading to an ICP. A VPN is also shown on one of the private paths.](e180f2b5fcbe8001554a7c0677cd3f82_img.jpg) + +The diagram illustrates the interconnection between a private network and a public network. On the left, the 'Private network' section contains two parallel paths. The top path consists of 'Private Local A', 'Private Transit B', and 'Private Transit A' connected in series. The bottom path consists of 'Private Local B', 'Private Transit C', and a 'VPN' block connected in series. Both paths converge at a vertical dashed line representing the network boundary. The top path connects to the 'Public network' at interface $T_T$ , while the bottom path connects at interface $T_L$ . The public network section includes a 'Local exchange', a 'Toll exchange', and an 'International switching center'. The connection ends at the 'ICP' (International Connection Point) at the far right. A legend at the bottom left defines the abbreviations: ICP (International Connection Point), $T_L$ (Access point to Local exchange of public network), $T_T$ (Access point to Toll exchange of public network), and VPN (Virtual Private Network). The diagram is labeled 'T1211040-99' at the bottom right. + +ICP International Connection Point + $T_L$ Access point to Local exchange of public network + $T_T$ Access point to Toll exchange of public network +VPN Virtual Private Network + +Diagram of basic configuration for the interconnection between private and public network. It shows two private network paths on the left connecting to a public network on the right via interfaces T\_T and T\_L. The public network includes a local exchange, a toll exchange, and an international switching center leading to an ICP. A VPN is also shown on one of the private paths. + +**Figure 1/G.108 – Basic configuration for the interconnection between private and public network** + +In Figure 1, which is generalized to include international scenarios, the public network, and therefore the entire connection, is shown only up to the International Connection Point, ICP, of an international switching centre. It is assumed, that the impairment allowance between the access points for calls within the national public network are allocated symmetrically with reference to the ICP, which can be considered as the virtual centre of the public network for international calls. Since calls can be terminated on both sides with private networks in the same configuration, it seems sufficient to draw the Figure in this simple way. For connections not involving an ICP, e.g. most connections within North America, the equivalent virtual centre can be assumed to be within the digital portion of the highest ranking network provider, generally an IC. + +The configuration shows two different types of interfaces between public and private networks, the one called $T_L$ , connects the private network to a local exchange (e.g. LEC), usually the lowest hierarchy and the common connection point in a public network. The other interface, called $T_T$ , connects the private network directly to a higher hierarchy level, e.g. an IC, bypassing the local exchange. In some cases, especially for larger private networks, by-pass may permit more allocation of specific transmission parameters, e.g. delay, to the private network. + +Figure 1 also illustrates the interconnection between the private Transit A and private Transit C exchanges using the feature of a Virtual Private Network VPN. For the purpose of transmission planning, this VPN, although part of the public network, should be considered as part of the private network. The same is valid for leased lines or tie trunks serving as transmission elements between different PBXs within the private network but usually provided by public network carriers. + +Where the private network includes leased lines or tie trunks, VPN connections, or Centrex terminals, the private network planner should obtain transmission planning information on these connections from the public network provider of these facilities or services. + +Figures 2 through 4 illustrate in more detail common configurations within the private network. Figure 2 shows a fully digital connection between a digital telephone set and the digital interfaces $T_L$ or $T_T$ to the public network. Assuming a fully bit-transparent transmission in all elements of the private network, this configuration can be considered as the quality optimum for a connection where the private network most likely contributes a minimum of transmission impairments to the overall connection. + +![Diagram of a standard configuration with a fully digital routing within the private network. The diagram shows a digital telephone set connected to a Private Local exchange (CE), which is connected via a Transmission Element (TE) to a Private Transit B exchange (CE). This is further connected via another TE to a Private Transit A exchange (CE). The Private Transit A exchange is connected to two digital access points, T_T (Toll exchange) and T_L (Local exchange). The diagram uses dashed lines for connections and solid lines for interfaces. Labels include: Private Local, Private Transit B, Private Transit A, Digital telephone set, CE, TE, T_T, T_L, and T1211050-99.](eb03559a4d92ea9ebd63ea9be663c50a_img.jpg) + +Diagram of a standard configuration with a fully digital routing within the private network. The diagram shows a digital telephone set connected to a Private Local exchange (CE), which is connected via a Transmission Element (TE) to a Private Transit B exchange (CE). This is further connected via another TE to a Private Transit A exchange (CE). The Private Transit A exchange is connected to two digital access points, T\_T (Toll exchange) and T\_L (Local exchange). The diagram uses dashed lines for connections and solid lines for interfaces. Labels include: Private Local, Private Transit B, Private Transit A, Digital telephone set, CE, TE, T\_T, T\_L, and T1211050-99. + +$T_L$ Digital access point at Local exchange + +$T_T$ Digital access point at Toll exchange + +CE Connection Element + +TE Transmission Element + +**Figure 2/G.108 – Standard configuration with a fully digital routing within the private network** + +![Figure 3/G.108 – Private Network with 4-wire/2-wire Conversion. This block diagram shows a signal path from an 'Analogue telephone set' on the left to digital access points 'T_T' and 'T_L' on the right. The path consists of: 'Analogue telephone set' connected to a 'Private Local' box (labeled 'CE' below); a solid line (labeled 'TE' below) connecting 'Private Local' to 'Private Transit B' box (labeled 'CE' below); inside 'Private Transit B', a 4-wire to 2-wire conversion symbol is shown; a dashed line (labeled 'TE' below) connects 'Private Transit B' to 'Private Transit A' box (labeled 'CE' below); and finally, dashed lines connect 'Private Transit A' to 'T_T' and 'T_L'.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg) + +Figure 3/G.108 – Private Network with 4-wire/2-wire Conversion. This block diagram shows a signal path from an 'Analogue telephone set' on the left to digital access points 'T\_T' and 'T\_L' on the right. The path consists of: 'Analogue telephone set' connected to a 'Private Local' box (labeled 'CE' below); a solid line (labeled 'TE' below) connecting 'Private Local' to 'Private Transit B' box (labeled 'CE' below); inside 'Private Transit B', a 4-wire to 2-wire conversion symbol is shown; a dashed line (labeled 'TE' below) connects 'Private Transit B' to 'Private Transit A' box (labeled 'CE' below); and finally, dashed lines connect 'Private Transit A' to 'T\_T' and 'T\_L'. + +$T_L$ Digital access point at Local exchange + $T_T$ Digital access point at Toll exchange + CE Connection Element + TE Transmission Element + +**Figure 3/G.108 – Private Network with 4-wire/2-wire Conversion** + +The configuration in Figure 3 assumes a 4-wire/2-wire conversion (hybrid) in the private Transit B switch and 2-wire facilities to the private terminating switch as well as to the analogue telephone set. In this case impairments due to loss in the 2-wire cable section should be expected. Furthermore, the hybrid in the Transit B switch may cause impairments with respect to being a possible source of echo for the far-end subscriber. This hybrid also forms the termination 4-wire connection with the public network and hence could influence the stability of the connection. + +![Figure 4/G.108 – Digitally connected wireless telephone set. This block diagram shows a signal path from a 'Wireless telephone set' on the left to digital access points 'T_T' and 'T_L' on the right. The path consists of: 'Wireless telephone set' connected to a 'Base station' box (labeled 'CE' below); a dashed line (labeled 'TE' below) connecting 'Base station' to 'Private Local' box (labeled 'CE' below); a dashed line (labeled 'TE' below) connecting 'Private Local' to 'Private Transit' box (labeled 'CE' below); and finally, dashed lines connect 'Private Transit' to 'T_T' and 'T_L'.](4b87467ad9642943235f48f7d4b59449_img.jpg) + +Figure 4/G.108 – Digitally connected wireless telephone set. This block diagram shows a signal path from a 'Wireless telephone set' on the left to digital access points 'T\_T' and 'T\_L' on the right. The path consists of: 'Wireless telephone set' connected to a 'Base station' box (labeled 'CE' below); a dashed line (labeled 'TE' below) connecting 'Base station' to 'Private Local' box (labeled 'CE' below); a dashed line (labeled 'TE' below) connecting 'Private Local' to 'Private Transit' box (labeled 'CE' below); and finally, dashed lines connect 'Private Transit' to 'T\_T' and 'T\_L'. + +$T_L$ Digital access point at Local exchange + $T_T$ Digital access point at Toll exchange + CE Connection Element + TE Transmission Element + +**Figure 4/G.108 – Digitally connected wireless telephone set** + +When wireless telephone sets serve as terminal elements, as shown in Figure 4, impairments due to additional delay and distortion should be subject to planning. In such configurations, the use of echo control devices should also be investigated. + +![Diagram illustrating the basic connection between the PSTN and an IP network with an H.323 terminal and a PBX connected via an IWF. The diagram shows a PBX connected to an IWF, which is connected to an IP Network. The IP Network is connected to an IP access, which is connected to an H.323 terminal. The IP Network is also connected to another IWF, which is connected to a PSTN. The PSTN is connected to a telephone handset. A label 'Local or distributed Interworking Functions' points to the IWF between the PBX and the IP Network. A label 'T1211080-99' is in the bottom right corner.](7133ccf78043568ca62ecbcd43628a4a_img.jpg) + +``` + +graph LR + PBX[PABX] --- IWF1[IWF] + IWF1 --- IPN((IP Network)) + IPN --- IPAC((IP access)) + IPAC --- H323[H.323 terminal] + IPN --- IWF2[IWF] + IWF2 --- PSTN((PSTN)) + PSTN --- PH[Telephone Handset] + LID[Local or distributed Interworking Functions] --> IWF1 + T1211080-99[T1211080-99] + +``` + +Diagram illustrating the basic connection between the PSTN and an IP network with an H.323 terminal and a PBX connected via an IWF. The diagram shows a PBX connected to an IWF, which is connected to an IP Network. The IP Network is connected to an IP access, which is connected to an H.323 terminal. The IP Network is also connected to another IWF, which is connected to a PSTN. The PSTN is connected to a telephone handset. A label 'Local or distributed Interworking Functions' points to the IWF between the PBX and the IP Network. A label 'T1211080-99' is in the bottom right corner. + +**Figure 5/G.108 – Basic connection between the PSTN and an IP network with its H.323 terminal and a PBX connected via an IWF** + +When IP-based networks serve as transmission elements (containing connection elements), as shown in Figure 5, impairments due to transcoding or tandeming of low bit-rate codecs and packet loss as well as additional delay should be subject to planning. For such configurations, the existence, necessity and the properties of echo control devices should also be investigated. + +# 6 Basic planning principle – the impairment factor method in conjunction with the E-Model + +As indicated in the introduction to this Recommendation, the rapidly changing scenario in the field of multiple interconnected networks (e.g. private networks) with increasing size and complexity, in combination with new technologies and the constraint for more economical solutions, requires more flexibility with respect to transmission planning. + +In general, the quality of speech transmission via telephone channels is based on a subjective judgement by the users at both ends. Therefore, transmission planning as given in Recommendation G.101 (The Transmission Plan) [2] is, in principle, derived from an end-to-end consideration in conjunction with a partitioning of all relevant parameters between different networks, or parts of a network. For private networks, this method was in common use in the field of regulation for all calls via the public network, providing limits for the private network between the acoustical interface of the telephone set and an electrical interface to the public network. These limits were defined to guarantee a sufficient quality for all calls (national and international). In North America, the public network providers usually mandated the allocation; in Europe, the allocation was governed by regulation. + +As networks become more complex (North American standards for internetworking are modernized, and European countries are moving into liberalization) this principle is no longer valid. In conjunction with increasing liberalization in many countries, the responsibility for a sufficient speech transmission quality is now shifted to the operator of the terminating (e.g. private) network. However, planning of such networks with respect to speech transmission quality needs knowledge and experience in the field of transmission parameters and their influence to quality. Therefore, it seems necessary to provide a planning method which is easy to handle and accompanied by comprehensive tutorial information and planning tools. This is the main task of this Recommendation. + +It should be noted that the preferable purpose of network planning is to control the summation of transmission impairments, caused by the different network elements in all possible configurations. It is not the task of network planning to limit the transmission impairment of a specific network + +element. Unless indicated otherwise, it is assumed that transmission, switching and terminal elements in general are designed to meet all relevant requirements as given in ITU-T Recommendations and in international or national standards applicable for this type of element. + +Based on subjective testing users' perception is expressed in terms of MOS, %GoB or %PoW. During transmission planning, however, it is not practical to perform subjective tests. Therefore, a method must be provided which enables the planner to combine, by calculation, all existing transmission impairments in the given connection to a total value of impairment. This calculation must be performed by using an algorithm based on subjective testing. In telephone connections consisting of a variety of network elements, different transmission parameters may also simultaneously contribute to the total impairment. Therefore, the planning method used must also incorporate combination effects. For all configurations subject to this Recommendation, the planning of speech transmission quality should be based on an end-to-end consideration rather than on a specification of individual objective parameter limits. + +For the calculation of the different impairment values, particularly if the combined effect from the presence of more than one parameter needs to be considered, computational models are used for planning purposes. Several such "rating-models" have been developed and were contained and described in former ITU-T and CCITT publications, which are no longer recommended for application and which today have bibliographic status only. Today, Recommendation G.107 [3] gives the algorithm for the so called E-Model as the common ITU-T Transmission Rating Model. + +Transmission planning, based on the E-Model as recommended, provides a prediction of the expected quality, as perceived by the user, for an investigated connection. Based on an end-to-end assessment for each transmission parameter (including the type and number of low bit-rate codecs) impairment values are derived. This method accounts for low bit-rate coding devices as well as for impairments introduced by standard PCM coders and for impairments not directly related to digital processing. The introduction of a quality issue for planning purposes also enables the private network operator to make the design of the network on a cost versus quality relation, taking into account the specific requirements for the private network. + +The basic planning principle, as used in this Recommendation, deviates from previous planning methods for network interconnection scenarios. End-to-end speech transmission quality is now expressed in terms of the E-Model Rating R, as a result of calculations with the E-Model. The E-Model Rating R can be transformed into other quality measures, which have been used in transmission planning before, such as Mean Opinion Score (MOS), Percentage Good or Better (%GoB) or Percentage Poor or Worse (%PoW), according to Annex B/G.107 [3]. + +Figure 6 is intended to show the relation and interdependency between Subjective MOS, Objective MOS, Predicted MOS and E-Model Rating R in detail. + +For clarification: + +- Subjective MOS – listening speech quality calculated by a "Subjective Test" according to Recommendation P.800 [30]. +- Objective MOS – measured listening speech quality, typically a comparison rating method. +- Predicted MOS – estimated conversational quality. + +The "system" box contains all the equipment (acoustic or electric input/output) which is to be tested (either subjectively or objectively). + +The "subjective test" is the auditory test to provide a subjective MOS (Mean Opinion Score). + +The "comparison rating method" is the objective measurement device (calibrated with the auditory test results) with "objective MOS" as the result. This result (in the case of testing a pure codec device) can additionally be transformed into the "equipment impairment factor" ( $I_e$ ), for use in the E-Model. Subjective and objective MOS' are transformed into an "equipment impairment factor" ( $I_e$ ), as described in Appendix I/G.113 [5]. + +The "E-Model" is a parameter based algorithm based on subjective test results of auditory tests done in the past with the "system" parameters (and $I_e$ values) as inputs. The result of the E-Model calculations is "E-Model Rating R" which can be transformed to "predicted MOS". + +![Figure 6/G.108 – The E-Model in the environment of subjective and objective testing. This block diagram shows the flow from 'Speech in' to a 'System' block, which outputs 'Speech out'. 'Parameters' from the system are fed into an 'E-Model' block. An 'Auditory test library' also feeds into the 'E-Model'. The 'E-Model' outputs an 'E-Model Rating' (R), which is converted to a 'Predicted MOS'. A 'Subjective test' (oval) provides 'Subjective MOS' data. This data is used for 'Calibration' of an 'Objective measure (Comparison rating method)' block. The 'Objective measure' outputs an 'Objective MOS', which is converted to an 'Ie' value. The 'Ie' value and 'Parameters' are fed into an 'Equipment impairment factor' block (referencing Appendix I/G.113), which then feeds into the 'E-Model'.](043e64d41a3368d138ace3816fd26469_img.jpg) + +Figure 6/G.108 – The E-Model in the environment of subjective and objective testing. This block diagram shows the flow from 'Speech in' to a 'System' block, which outputs 'Speech out'. 'Parameters' from the system are fed into an 'E-Model' block. An 'Auditory test library' also feeds into the 'E-Model'. The 'E-Model' outputs an 'E-Model Rating' (R), which is converted to a 'Predicted MOS'. A 'Subjective test' (oval) provides 'Subjective MOS' data. This data is used for 'Calibration' of an 'Objective measure (Comparison rating method)' block. The 'Objective measure' outputs an 'Objective MOS', which is converted to an 'Ie' value. The 'Ie' value and 'Parameters' are fed into an 'Equipment impairment factor' block (referencing Appendix I/G.113), which then feeds into the 'E-Model'. + +Figure 6/G.108 – The E-Model in the environment of subjective and objective testing + +This basic principle is applied not only for internal calls within the network under consideration, but also for calls via public networks. For calls via public networks, illustrated in Figure 7, application of the "end-to-end principle" addresses parts of a connection which are not directly subject to planning by the network planner. Impairments caused by the public network (or tandem connections via more than one public network) and the far-end termination should be determinable and included in the transmission planning. In practice, this may cause some problems for planning, since those values may be not available in all cases, particularly for the far-end termination. In those situations, average values for different transmission parameters can be used, such values are provided in this Recommendation (see A.3) for basic terminations (single telephone set, private network). Minor problems may arise for the public network sections. Information about impairments for different routings should be available by negotiations between the public network provider and the private network planner. However, judicious application of impairment parameters in public network sections allows for a differentiation for the type of calls, national local, national long distance and international, and possibly different the allocation of impairments for the benefit of the private network design. + +![Figure 7/G.108 – General configuration for calls via public networks. This diagram shows a call path from a 'Terminating network' (labeled 'Private network (as an example)') through 'Transit network(s)' (labeled 'Public network(s)') to another 'Terminating network' (labeled 'Far-end termination'). The first 'Terminating network' and the start of the 'Transit network(s)' are grouped as the 'Planning section'.](e90987faabad6a6665cd8ed1151dc474_img.jpg) + +Figure 7/G.108 – General configuration for calls via public networks. This diagram shows a call path from a 'Terminating network' (labeled 'Private network (as an example)') through 'Transit network(s)' (labeled 'Public network(s)') to another 'Terminating network' (labeled 'Far-end termination'). The first 'Terminating network' and the start of the 'Transit network(s)' are grouped as the 'Planning section'. + +Figure 7/G.108 – General configuration for calls via public networks + +The impairment factor method is based on the assumption that transmission impairments can be transformed into psychological factors and that these psychological factors are additive on the "Psychological scale" as shown in Figure 8. + +![Figure 8/G.108 – Example for the addition of impairments on a 'Psychological scale'. The diagram shows a horizontal line representing the 'Psychological scale for the perception of quality'. Above the line, three arrows point to different segments, labeled 'I-value for echo', 'I-value for Ie', and 'I-value for OLR'. These three values are summed to represent the total impairment. The scale is divided into three regions: 'Optimum quality', 'Average quality', and 'Low quality'. A dashed line on the right indicates the end of the scale, with the text 'T1211110-99'.](d17aa1fcc3b86503ad1dd0717a6c34c2_img.jpg) + +*I-value for echo + I-value for Ie + I-value for OLR = Sum of impairments* + +Optimum quality                      Average quality                      Low quality                      T1211110-99 + +"Psychological scale for the perception of quality" → + +Figure 8/G.108 – Example for the addition of impairments on a 'Psychological scale'. The diagram shows a horizontal line representing the 'Psychological scale for the perception of quality'. Above the line, three arrows point to different segments, labeled 'I-value for echo', 'I-value for Ie', and 'I-value for OLR'. These three values are summed to represent the total impairment. The scale is divided into three regions: 'Optimum quality', 'Average quality', and 'Low quality'. A dashed line on the right indicates the end of the scale, with the text 'T1211110-99'. + +**Figure 8/G.108 – Example for the addition of impairments on a "Psychological scale"** + +An appropriate mathematical algorithm is provided by the E-Model, with which the different transmission parameters can be transformed into different "impairment factors". This method and the algorithm of the E-Model also include the combination effects of those impairments in the considered connection which occur simultaneously as well as some masking effects. With the E-Model, a very useful tool is available, which provides a simplified and easy-to-handle method for practical planning purposes. + +The final result of any calculation with the E-Model is the E-Model Rating R. The relation between the different impairment values and R is given by the equation: + +$$R = R_o - I_s - I_d - I_e + A$$ + +The term $R_o$ expresses the basic signal-to-noise ratio. + +The term $I_s$ represents all impairments which occur more or less simultaneously with the voice signal, such as: too loud speech level (non-optimum OLR), non-optimum sidetone (STMR), quantization noise (qdu), etc. + +The "delay impairment" factor $I_d$ sums all impairments due to delay and echo effects, and the "equipment impairment factor" ( $I_e$ ), represents impairments which are caused by low bit-rate codecs used in special equipment. + +The "advantage factor" $A$ represents an "advantage of access" which certain systems may provide in comparison to conventional systems. While all other impairment factors are subtracted from the basic signal-to-noise ratio $R_o$ , this value is added and thus compensates other impairments to a certain amount. It can be used to take into account the fact that the user will tolerate some decrease in transmission quality in exchange for the "advantage of access". Examples of such advantages are cordless and mobile systems or connections into hard-to-reach regions via multi satellite hops. The use and the amount of the advantage factor $A$ fall into the responsibility of the individual transmission planner and are for further study. + +High values of the E-Model Rating $R$ in a range of $90 \leq R < 100$ should be interpreted as excellent quality, while a lower value of $R$ indicates a lower quality. + +It should be noted, that, in some cases, not only the final result for $R$ is of interest, but also the specific impairment values $I_s$ , $I_d$ and $I_e$ . Their individual contribution to the total value of impairments can be used for the determination of the major impairments in the given configuration and for possible solutions for the reduction of these impairments' severity: e.g. reducing $I_d$ by the insertion of echo cancellers. + +Table 1 which has been taken from Recommendation G.109 [4] relates the E-Model Ratings R to categories of speech transmission quality and to user satisfaction. + +**Table 1/G.108 – Definition of categories of speech transmission quality** + +| Range of E-Model Rating R | Speech transmission quality category | User satisfaction | +|----------------------------------|---------------------------------------------|-------------------------------| +| $90 \leq R < 100$ | Best | Very satisfied | +| $80 \leq R < 90$ | High | Satisfied | +| $70 \leq R < 80$ | Medium | Some users dissatisfied | +| $60 \leq R < 70$ | Low | Many users dissatisfied | +| $50 \leq R < 60$ | Poor | Nearly all users dissatisfied | + +NOTE 1 – Connections with E-Model Ratings R below 50 are not recommended. +NOTE 2 – Although the trend in transmission planning is to use E-Model Ratings R, equations to convert E-Model Ratings R into other metrics, e.g. MOS, %GoB, %PoW can be found in Annex B/G.107 [3]. + +The E-Model and its algorithm require the following input parameters: + +- **SLR** **Send Loudness Rating;** +- **RLR** **Receive Loudness Rating;** +- **OLR** **Overall Loudness Rating1;** +- **STMR** **Sidetone Masking Rating2;** +- **LSTR** **Listener Sidetone Rating2;** +- **Ds** **D-value of telephone at send-side;** +- **Dr** **D-value of telephone at receive-side2;** +- **TELR** **Talker Echo Loudness Rating;** +- **WEPL** **Weighted Echo Path Loss;** +- **T** **Mean one way delay of the echo path;** +- **Tr** **Roundtrip delay in a closed 4-wire loop;** +- **Ta** **Absolute delay in echofree connections;** +- **qdu** **Number of quantization distortion units;** +- **Ie** **Equipment impairment factor (low bit-rate codecs);** +- **Nc** **Circuit noise referred to the 0 dBr-point;** +- **Nfor** **Noise floor at the receive-side;** +- **Ps** **Room noise at the send-side;** +- **Pr** **Room noise at the receive-side;** +- **A** **Advantage factor** + +1 No direct input value; calculated as $OLR = SLR + RLR$ . + +2 These parameters have a fixed relation by: $LSTR = STMR + Dr$ . + +Only those parameters indicated by bold letters are usually subject to planning. The other parameters can be set to default values. For more details see clause 7. + +A detailed description of the complete algorithm is given in Recommendation G.107 [3]. For information about the practical use of the E-Model for planning purposes see clause 9. + +# 7 Parameters subject to planning and their limits + +As stated in the scope, this Recommendation provides mainly examples based on connections with digital interfaces between private and public networks and with digital media for the main transmission elements within the private network. As networks and network elements migrate from analogue to digital, certain transmission parameters become of more significance with respect to the end-to-end speech quality and more important for planning purposes while others are reduced to minor influence or can even be neglected. Subclauses 7.1 through 7.9 describe those parameters which, in a mainly digital environment, should be subject to planning; subclause 7.10 deals with those parameters which, for the benefit of simplification, can be neglected or considered only in special applications. + +## 7.1 Overall Loudness Rating + +Although digital interfaces to other, mainly public, networks and digital transmission media for the main transmission elements within the private networks are the prime focus, the Overall Loudness Rating (OLR) of a connection should be considered. For economic reasons, portions of private networks may continue to rely on 2-wire analogue lines and on connection elements (PBXs) with analogue switching technology, thereby contributing impairments generally associated with the analogue environment, such as loss and noise. Likewise, within public networks, fully digital routing and termination cannot be assumed for all connections. + +Basically, the OLR of a connection is calculated as the sum of the Send Loudness Rating (SLR), of the telephone set at one end, the Receive Loudness Rating (RLR), of the other end set, and the Circuit Loudness Rating (CLR), representing the sum of all analogue and digital losses between these telephone sets. + +$$\text{OLR} = \text{SLR} + \text{CLR} + \text{RLR}$$ + +Impairments due to OLR may result from either too high or too low values of OLR. The optimum value lies in the range from 6 to 10 dB. Connections between two digital telephone sets, i.e. designed according to Recommendation P.310 [27], reference [42] with $\text{SLR} = 8$ dB and $\text{RLR} = 2$ dB, or to reference [49] with $\text{SLR} = 7$ dB and $\text{RLR} = 3$ dB, and routed over a fully digital connection, will meet this optimum value for OLR (10 dB). The relation between the E-Model Rating R and the OLR of a connection is shown in Figure 9. This graph, calculated with the E-Model, is obtained when all other input parameters of the E-Model are set to their default values (see 9.7); i.e. OLR is the only impairment in the connection considered. + +![Figure 9/G.108 – Relation between OLR and E-Model Rating R. The graph shows a curve representing the relationship between Overall Loudness Rating (OLR) on the x-axis and E-Model Rating R on the y-axis. The x-axis ranges from -10 to 40 dB, and the y-axis ranges from 50 to 100. The curve starts at approximately (-10, 68), rises to a peak of about 96 at OLR = 8 dB, and then declines to approximately (40, 52).](bafe3665fa89ba09857af5a2532c79fe_img.jpg) + +| Overall Loudness Rating (OLR) [dB] | E-Model Rating R | +|------------------------------------|------------------| +| -10 | 68 | +| 0 | 85 | +| 8 | 96 | +| 20 | 80 | +| 30 | 65 | +| 40 | 52 | + +Figure 9/G.108 – Relation between OLR and E-Model Rating R. The graph shows a curve representing the relationship between Overall Loudness Rating (OLR) on the x-axis and E-Model Rating R on the y-axis. The x-axis ranges from -10 to 40 dB, and the y-axis ranges from 50 to 100. The curve starts at approximately (-10, 68), rises to a peak of about 96 at OLR = 8 dB, and then declines to approximately (40, 52). + +**Figure 9/G.108 – Relation between OLR and E-Model Rating R** + +Comparing the graph in Figure 9 with the definition of categories of speech transmission quality in Table 1, a range for the OLR from $-10$ dB to $30$ dB delivers quality between "best" and "low". However, the value $30$ dB for a connection should be considered as an absolute upper limit which should never be exceeded, not even in exceptional cases. For a speech transmission quality in the "medium" category, the preferred limit for standard connections, the upper value for OLR is recommended to be in the range of $20$ dB to $25$ dB. Low values of OLR may exist for internal connections within a private network between two analogue telephone sets, or if digital telephone sets with lower values for SLR and/or RLR than those given in Recommendation P.310 [27] and references [42] or [49] are used. Very low values for OLR should be avoided. For $OLR < 0$ dB the insertion of additional loss is recommended. + +## 7.2 Echo + +As stated above, fully digital routing cannot be assumed in all configurations. Mixed analogue/digital routing, within private and public networks, generally implies the presence of 4-wire/2-wire conversions; there signal reflections, together with transmission delay, might cause impairments due to talker echo which must be taken into account. Signal reflections will mainly occur at hybrids, where the bidirectional path of the connection between the talker's telephone set and the hybrid forms the "echo path". In some connections with multiple conversion points, there are multiple echo paths. + +The effects of echo in a conversation can cause impairments to the talker as well as to the listener. These impairments are expressed as Talker Echo and Listener Echo, respectively. More information about these effects is given in Recommendation G.131 [9] and Recommendation G.126 [8]. As a general rule, listener echo can be neglected if there is sufficient control of the talker echo. + +The impairment due to talker echo depends on two factors, the delay and the level of the reflected speech signal received by the talker. The perceived quality decreases with increasing delay and/or increasing level of the received echo signal. + +For planning purposes, the transmission delay ( $T$ ), is defined as the mean one-way transmission time of the echo path. Although the total transmission time between the talker's telephone set and the hybrid and back to the talker constitutes the delay of the echo, the mean one-way transmission time is used in the E-Model calculations, assuming that, for most configurations, the transmission time is nearly equal in both transmission directions. + +![Figure 10/G.108 – E-Model Rating R due to talker echo. A line graph showing the relationship between Mean one-way delay T in ms (x-axis, 0 to 50) and E-Model Rating R (y-axis, 50 to 100). Three curves are plotted for different TELR values: 50 dB (circles), 40 dB (crosses), and 30 dB (triangles). All curves show a decrease in R as T increases. The 50 dB curve is the highest, followed by 40 dB, and then 30 dB.](48a08e5cabec8b75386679d8a57dec3e_img.jpg) + +| Mean one-way delay T (ms) | R (50 dB TELR) | R (40 dB TELR) | R (30 dB TELR) | +|---------------------------|----------------|----------------|----------------| +| 0 | 95 | 95 | 95 | +| 10 | 94 | 92 | 85 | +| 20 | 93 | 89 | 75 | +| 30 | 92 | 85 | 65 | +| 40 | 91 | 81 | 58 | +| 50 | 90 | 76 | 53 | + +Figure 10/G.108 – E-Model Rating R due to talker echo. A line graph showing the relationship between Mean one-way delay T in ms (x-axis, 0 to 50) and E-Model Rating R (y-axis, 50 to 100). Three curves are plotted for different TELR values: 50 dB (circles), 40 dB (crosses), and 30 dB (triangles). All curves show a decrease in R as T increases. The 50 dB curve is the highest, followed by 40 dB, and then 30 dB. + +**Figure 10/G.108 – E-Model Rating R due to talker echo** + +For planning calculations, the level of the received echo signal, as an input parameter to the E-Model, is expressed as the Talker Echo Loudness Rating (TELR). TELR is defined as the sum of SLR and RLR of the talker's telephone set and the Echo Loss EL of the echo path. The Echo Loss (EL) includes losses in the bidirectional transmission path and the TBRL (see A.1.3) at the 4-wire/2-wire conversion point. + +$$\text{TELR} = \text{SLR} + \text{EL} + \text{RLR}$$ + +The relation between the mean one-way delay (T), and the E-Model Rating R is shown in Figure 10 for three different values of TELR. The graphs are calculated with all other parameters set to their default value. + +Talker echo is the most important parameter in modern mixed digital/analogue networks. + +Improvements in perceived quality with respect to talker echo can either be achieved by higher values of TELR or by lower values of mean one-way delay (T), or by a combination of both: + +- The value of TELR can be increased by improvements in the 4-wire/2-wire conversion (increasing the TBRL), or by deliberately increasing the loss in the connection. However, in a given connection, increasing the TELR by adding loss is limited to avoid too large values of the OLR (note, however, that for every dB increase in the OLR, the TELR will increase by two dB). When the loss value, which would be required to achieve adequate TELR, results in excessive OLR, the use of Echo Cancellers (EC), should be considered. Information about EC application is given in clause 10. +- To decrease the value of the mean one-way delay (T) during transmission planning, it should be considered that, in modern networks, two categories of delay "sources" contribute to the end-to-end value of T. The first category comprises the traditional distance-related delay sources, e.g. analogue or digital cable sections (including switching facilities). The second category comprises modern signal processing devices as delay sources, e.g. low bit-rate codecs, where the value of the delay depends only on the type and number of the equipment inserted into a connection. Decreasing the value of T for the first category yields to possibly avoiding indirect routing, while for the second category the type and number of such signal processing devices might be changed as a result of transmission planning. + +To achieve a speech transmission quality in the "high" category with a E-Model Rating $R \geq 80$ (see Table 1), Figure 10 shows that, with TELR = 30 dB, the mean one-way delay is limited to $T = 14$ ms, while with TELR = 40 dB a value of $T = 39$ ms can be tolerated. In practice, values for TELR will, in most applications, be in the range of 30 dB to 40 dB. Thus, for connections with an echo path of more than 20 to 25 ms mean one-way delay, it is advisable to thoroughly investigate the impairments due to echo effects and to consider the possible use of echo cancellers. + +Very low values of the mean one-way delay with $T < 1.5$ ms, are considered as sidetone and need not be investigated as an impairment due to echo. For low values of the Sidetone Masking Rating, $STMR < 9$ dB some masking of the talker echo may be observed. This effect is included in the algorithm of the E-Model. + +In planning practice, it is necessary to clearly identify the echo path in a connection. As noted, more than one echo path may exist in some configurations. For planning rules in those situations, see 8.2.2 and 9.5. + +## 7.3 Transmission time in echofree connections + +As networks and network elements migrate from analogue to digital, transmission time in echofree connections becomes of more significance with respect to the end-to-end speech quality and more important for planning purposes, besides general considerations, the awareness of the specific mechanisms of codec-related processing delay needs particular attention. + +### 7.3.1 General considerations + +Additional impairments may arise due to very long delay, even if perfect echo cancelling is provided. Typically, this occurs on international or intercontinental connections carried via satellite links, or submarine cables, but also national or internal connections within the network under consideration may be affected, if modern signal processing devices, like low bit-rate codecs, are inserted. Very long delay may result in difficulties during conversation. According to subjective tests, this effect is encountered mainly for a one-way transmission time of more than 150 ms. + +The relevant parameter for planning is the Absolute Delay ( $T_a$ ), in ms, defined as the mean one-way delay between the two telephone sets, independent of the number of echo paths in the same connection. The E-Model Rating $R_i$ is shown in Figure 11 for a range of $T_a = 100$ to 600 ms, with all other parameters at their default values. + +![Figure 11/G.108 – Relation between absolute delay (Ta) and E-Model Rating R. The graph shows a curve starting at R ≈ 94 for Ta = 100 ms and decreasing to R ≈ 59 for Ta = 600 ms.](db2f2503931949e0258f7f10eba14eb5_img.jpg) + +The graph shows the relationship between Absolute delay ( $T_a$ ) in ms on the x-axis and E-Model Rating $R$ on the y-axis. The x-axis ranges from 100 to 600 ms with major grid lines every 100 ms. The y-axis ranges from 50 to 100 with major grid lines every 5 units. The curve starts at approximately $R = 94$ for $T_a = 100$ ms, remains relatively flat until about $T_a = 150$ ms, and then decreases steadily to approximately $R = 59$ at $T_a = 600$ ms. + +| Absolute delay ( $T_a$ ) in ms | E-Model Rating $R$ | +|--------------------------------|--------------------| +| 100 | 94 | +| 200 | 91 | +| 300 | 80 | +| 400 | 70 | +| 500 | 64 | +| 600 | 59 | + +Figure 11/G.108 – Relation between absolute delay (Ta) and E-Model Rating R. The graph shows a curve starting at R ≈ 94 for Ta = 100 ms and decreasing to R ≈ 59 for Ta = 600 ms. + +Figure 11/G.108 – Relation between absolute delay ( $T_a$ ) and E-Model Rating $R$ + +With respect to a speech transmission quality in the "medium" category as described in Table 1, the limit value for most connections should be in the range of 300 to 350 ms with an upper limit of 400 ms. This is also in accordance with Recommendation G.114 [6] and should be exceeded in exceptional cases, only. + +### **7.3.2 Considerations with respect to low bit-rate coders** + +Modern speech codecs operate on collections of speech samples known as frames. Each block of input speech samples is processed into a compressed frame. The coded speech frame is not generated until all speech samples in the input block have been collected by the encoder. Thus, there is a delay of one frame before processing can begin. In addition, many coders also look into the succeeding frame to improve compression efficiency. The length of this advance look is known as the look-ahead time of the coder. The time required to process an input frame is assumed to be the same as the frame length since efficient use of processor resources will be accomplished when an encoder/decoder pair (or multiple encoder/decoder pairs operating in parallel on multiple input streams) fully uses the available processing power (evenly distributed in the time domain). Thus, the delay through an encoder/decoder pair is normally assumed to be: + +$$2 \times \text{frame size} + \text{look-ahead}$$ + +#### **7.3.2.1 Delay in wirebound environment** + +If the output facility is running at the same rate as the speech codec (e.g. an 8 kbit/s facility for G.729), then an additional frame of delay is incurred when clocking the compressed frame to the facility. Thus, the maximum delay attributable to codec-related processing in conventional wirebound systems (i.e. the PSTN) is: + +$$3 \times \text{frame size} + \text{look-ahead}$$ + +#### **7.3.2.2 Delay in mobile and wireless environment** + +If the output facility is a mobile network or a cordless facility, then the frame output by the encoder will function similar to the operation in wirebound environment (see 7.3.2.1) but an additional delay is incurred for attaching the compressed frame to the airpath (assumed again that the mobile facility is running at the same rate as the speech codec). Thus, the maximum delay attributable to codec-related processing in mobile and wireless systems is: + +$$3 \times \text{frame size} + \text{look-ahead} + \text{air interface framing}$$ + +#### **7.3.2.3 Delay in IP environment (one frame per packet)** + +If the output facility is an IP network, then the frame output by the encoder will instantaneously be dropped into an IP packet. The additional delay required for IP packet assembly and presentation to the underlying link layer will depend on the link layer. When the link layer is a LAN (e.g. Ethernet), this additional time will usually be quite small. Thus, the minimum delay attributable to codec-related processing in IP-based systems is: + +$$2 \times \text{frame size} + \text{look-ahead}$$ + +When the link layer is one with lower clock rate (e.g. modem connection) or one with high traffic load (e.g., congested LAN), the additional delay will increase substantially. In order to clock compressed frames at least with the same rate to the facility as the speech samples are collected at the input of the encoder, the additional delay should not exceed one frame size. Thus, the maximum delay attributable to codec-related processing in IP based systems operation in real-time is: + +$$3 \times \text{frame size} + \text{look-ahead}$$ + +#### 7.3.2.4 Delay in IP environment (multiple frames per packet) + +If multiple voice frames are grouped together into a single IP packet, further delay is added to the speech signal. This delay will be at least the duration of one extra voice frame at the encoder for each additional voice frame added to the IP packet. Thus, the minimum delay attributable to codec-related processing in IP based systems with multiple frames per packet is: + +$$(N+1) \times \text{frame size} + \text{look-ahead},$$ + +where N is the number of frames in each packet. + +When the link layer is one with lower clock rate (e.g. modem connection) or one with high traffic load (e.g. congested LAN), additional delay will be incurred in delivering the packet to the facility. In order to clock compressed frames, at least with the same rate to the facility as the speech samples are collected at the input of the encoder, the additional delay should, in case of multiple frames per packet, not exceed the length of the frames contained in one packet. It should be noted that clocking out a packet to the IP facility cannot start before all speech frames for this packet are available. Thus, the maximum delay attributable to codec-related processing in IP based systems operating in real-time with multiple frames per packet is: + +$$(2N+1) \times \text{frame size} + \text{look-ahead}$$ + +where N is the number of frames in each packet. + +## 7.4 Stability + +The stability of a connection should be investigated in transmission planning for any connection, where the network under consideration contains a 4-wire loop or where a 2-wire/4-wire conversion (hybrid) within the network under consideration together with a 4-wire/2-wire conversion within the public network or the far-end termination forms a 4-wire loop. For further information about stability see also Recommendation G.122 [7]. + +Insufficient stability may cause "singing" within the 4-wire loop, which must always be avoided. Although stability is more a problem during call setup and release (due to lower balance return loss at hybrids during these states) and usually does not impact the talking state, a circuit with singing may disturb other channels of a telecommunication network via crosstalk, mainly in analogue systems. The main parameter to control stability is the so called "Open Loop Loss (OLL)", the sum of all losses and gains in the 4-wire loop. The term stability defines the margin ("singing margin") between the actual OLL and the point where singing, usually at some frequency within the voiceband may arise. The most critical configurations during call setup are the open and short circuit conditions at the 2-wire sides of the hybrids terminating the ends of the 4-wire loop. + +Since singing will not normally occur during the talking state (when proper termination at the 2-wire ends are present), stability is not a factor in the assessment of speech quality. Nevertheless, it should be considered during transmission planning. This must be done in a separate calculation, since the E-Model does not include an algorithm for calculating the stability of 4-wire loops. To avoid singing or "near-singing" (a situation close to the singing point), the stability (OLL) in every 4-wire loop should be at least 4-6 dB for every frequency in the voiceband. If a private network contains only one end of a 4-wire loop, e.g. in connections via a public network, the stability loss at the interface between private and public network should, for all possible connection scenarios, be greater than 6 dB for every frequency in the voiceband. + +Connections including one or more 4-wire loops as a source for signal reflections, may, during talking state, contribute talker echo impairments due to multiple echoes as well as listener echo impairments. For information about listener echo as a subject of planning, see 7.10.3. + +## 7.5 Quantization distortion units + +Inherent to the process of PCM encoding and decoding according to the "8 bit-law" (A-law or $\mu$ -law) as described in Recommendation G.711 [15], Tables 5 and 6, is an impairment known as "quantization distortion". This impairment is perceived as a quantization noise accompanying the received voice signal (i.e. it is not perceived in a quiescent channel), thereby, reducing the signal-to-noise ratio. Quantization distortions are additive, i.e. every A/D-D/A conversion will contribute additional noise. + +For transmission planning, it is common practice to express quantization noise in "quantization distortion unit" (qdu); setting a limit for the maximum number of acceptable qdu in a connection. One qdu is defined as the quantization noise arising from a complete encoding from analogue into digital (A/D) and again decoding from digital into the analogue (D/A) signal form according to Recommendation G.711 [15]. + +With the increasing use of digital transmission and connection elements in private and public networks, the importance of quantization noise will decrease. However, quantization distortion can be ignored in planning only if fully bit-transparent routing can be assumed. Whenever mixed digital/analogue elements are present in a connection, the resulting number of qdu needs to be subject to planning. The influence of the number of qdus in a connection to the E-Model Rating R is shown in Figure 12. + +![Figure 12/G.108 – Relation between the number of qdu and E-Model Rating R. The graph shows a curve starting at R ≈ 94 for 1 qdu and decreasing to R ≈ 73 for 15 qdus. The x-axis is 'Number of qdu' (1-15) and the y-axis is 'R' (50-100).](3fe839e8110987c60318d18e542f4a10_img.jpg) + +| Number of qdu | E-Model Rating R | +|---------------|------------------| +| 1 | 94 | +| 2 | 94 | +| 3 | 94 | +| 4 | 94 | +| 5 | 93 | +| 6 | 92 | +| 7 | 90 | +| 8 | 88 | +| 9 | 85 | +| 10 | 82 | +| 11 | 79 | +| 12 | 76 | +| 13 | 74 | +| 14 | 72 | +| 15 | 73 | + +Figure 12/G.108 – Relation between the number of qdu and E-Model Rating R. The graph shows a curve starting at R ≈ 94 for 1 qdu and decreasing to R ≈ 73 for 15 qdus. The x-axis is 'Number of qdu' (1-15) and the y-axis is 'R' (50-100). + +Figure 12/G.108 – Relation between the number of qdu and E-Model Rating R + +The graph in Figure 12, derived from the E-Model with all other parameters at their default values, shows that the impairments are negligible for an aggregate distortion of up to 4 or 5 qdus. However, connections with more than one qdu will usually also be influenced by other impairments, such as loss and echo effects, such that the sum of all impairments influences the perceived speech quality. Because the E-Model calculations always include the number of qdu as an input parameter, it is recommended that the correct number of qdu of the connection be determined and used as an input to the model instead of the default value (1 qdu). + +The parameter qdu in transmission planning applies not only to A/D-D/A conversions but also to other processes influencing the digital bit-stream. Those processes are, for example, the insertion of digital loss or gain, signal addition in conference circuits, use of digital echo cancellers, etc. For coding laws other than A-law/ $\mu$ -law (e.g. according to Recommendations G.726, G.727 and G.728), the parameter qdu is, for transmission planning, replaced by the equipment impairment factor ( $I_e$ ) (see 7.6). + +## 7.6 Equipment impairment factor + +Modern coding laws, like those associated with low bit-rate codecs as described in the G.720-series of Recommendations or the GSM Standards, as well as ADPCM with different operating bit-rates, will contribute distortions resulting in a decrease of the perceived speech quality. Contrary to the quantization distortion due to the standard 8 bit PCM coding (A-law or $\mu$ -law), these impairments can not readily be quantified with a number of qdu. For planning purposes, the impairments introduced by the different types of codecs are expressed by the "equipment impairment factor" ( $I_e$ ). $I_e$ values are obtained by subjective or objective tests, see Figure 6 for details. The results of these subjective or objective mean opinion scores are transformed into a value, $I_e$ , which follows the basic planning principle described in 6.1 (addition of impairments on a linear psychological scale) and which, therefore, can be directly used as an input parameter for the E-Model. + +Some provisional planning values of the equipment impairment factor $I_e$ for several codec types are listed in Table 2a. For up to date information on those values and on values for other codec types, Appendix I/G.113 [5] may provide guidance (Appendix I/G.113 [5] is intended to be updated regularly). + +**Table 2a/G.108 – Provisional planning values for the equipment impairment factor ( $I_e$ )** + +| Codec type | Reference | Operating rate kbit/s | $I_e$ value | +|------------|-------------------------------|-----------------------|-------------| +| ADPCM | G.726, G.727 | 40 | 2 | +| | G.721(1988), G.726, G.727 | 32 | 7 | +| | G.726, G.727 | 24 | 25 | +| | G.726, G.727 | 16 | 50 | +| LD-CELP | G.728 | 16 | 7 | +| | | 12.8 | 20 | +| CS-ACELP | G.729 | 8 | 10 | +| | G.729-A + VAD | 8 | 11 | +| VSELP | IS-54 | 8 | 20 | +| ACELP | IS-641 | 7.4 | 10 | +| QCELP | IS-96-A | 8 | 19 | +| RCELP | IS-127 | 8 | 6 | +| VSELP | Japanese PDC | 6.7 | 24 | +| RPE-LTP | GSM 06.10, Full-rate | 13 | 20 | +| VSELP | GSM 06.20, Half-rate | 5.6 | 23 | +| ACELP | GSM 06.60, Enhanced Full Rate | 12.2 | 5 | +| ACELP | G.723.1 | 5.3 | 19 | +| MP-MLQ | G.723.1 | 6.3 | 15 | + +The speech codecs and systems mentioned in Table 2a are briefly described below. + +**IS-54** First generation digital TDMA cellular system in North-America utilizing Vector Sum Excited Linear Prediction (VSELP) coding at a net bit rate of 7.95 kbit/s (plus 5.05 kbit/s FEC) [45]. + +**IS-96-A** First generation digital CDMA cellular system in North-America utilizing Qualcomm Code-Excited Linear Prediction (QCELP) coding at a variable net bit rate of 8, 4 and 2 kbit/s [46]. + +- IS-127** Second generation digital CDMA cellular system in North-America utilizing Residual Code-Excited Linear Prediction (RCELP) coding at a variable net bit rate of 8, 4 and 2 kbit/s [47]. +- IS-641** Second generation digital TDMA cellular system in North-America utilizing Algebraic Code-Excited Linear Prediction (ACELP) coding at a net bit rate of 7.4 kbit/s (plus 5.6 kbit/s FEC) [48]. +- GSM-FR** First generation digital European Global System for Mobile Communication (GSM) cellular system utilizing Regular Pulse Excitation Long Term Prediction (RPE-LTP) coding at a net bit rate of 13 kbit/s (plus 9.8 kbit/s FEC) [56]. +- GSM-HR** Half-rate version of the voice codec for the GSM system utilizing Vector Sum Excited Linear Prediction (VSELP) coding at a net bit rate of 5.6 kbit/s [57]. +- GSM-EFR** Second generation speech codec of the digital European Global System for Mobile Communication (GSM) cellular system utilizing Algebraic Code-Excited Linear Prediction (ACELP) coding at a net bit rate of 12.2 kbit/s (plus 10.6 kbit/s FEC) [58]. +- PDC** First generation digital Japanese Personal Digital Communication (PDC) system utilizing a Japanese version of Vector Sum Excited Linear Prediction (JVSELP) coding at a net bit rate of 6.7 kbit/s (plus 4.5 kbit/s FEC) [62]. +- G.723.1** ITU-T standard for speech coding in PSTN videophones utilizing Algebraic Code-Excited Linear Prediction (ACELP) coding at 5.3 kbit/s and Multipulse Maximum Likelihood Quantization (MP-MLQ) at 6.3 kbit/s [16]. +- G.726** ITU-T standard for speech coding at 40, 32, 24, and 16 kbit/s utilizing Adaptive Differential Pulse Code Modulation (ADPCM) [18], see also Recommendation G.721 [17] and Recommendation G.727 [19]. +- G.728** ITU-T standard for speech coding at 16 kbit/s utilizing Low-Delay Code-Excited Linear Prediction (LD-CELP) coding [20]. This algorithm also has 12.8 and 9.6 kbit/s bit rate extensions [21]. +- G.729** ITU-T standard for speech coding at 8 kbit/s utilizing Conjugate Structure Algebraic Code-Excited Linear Prediction (CS-ACELP) coding [22]. This algorithm also has 6.4 and 11.8 kbit/s bit rate extensions [23] and [24]. + +### **7.6.1 Equipment impairment factor for codecs under conditions of packet loss** + +Table 2a of *Ie* values refers to non-error conditions. For propagation errors and frame-erasures or packet loss, no definite values are available which would be valid for more than one codec or codec family. In order to help the transmission planner, examples of *Ie* values under conditions of packet loss are given in Table 2b and for propagation error patterns EP 1 and EP 2 in Table 2c. These values are provisional only as they were determined in single experiments. + +**Table 2b/G.108 – Provisional planning values for the equipment impairment factor ( $I_e$ ) under conditions of packet loss, codecs G.729-A + VAD and G.723.1-A + VAD** + +| % Packet loss | I_e for G.729-A + VAD | I_e for G.723.1-A + VAD 6.3 kbit/s | +|----------------------|-------------------------------------------|--------------------------------------------------------| +| 0 | 11 | 15 | +| 0.5 | 13 | 17 | +| 1 | 15 | 19 | +| 1.5 | 17 | 22 | +| 2 | 19 | 24 | +| 3 | 23 | 27 | +| 4 | 26 | 32 | +| 8 | 36 | 41 | +| 16 | 49 | 55 | + +NOTE – No. frames per packet: +– G.729-A + VAD: 2; +– G.723.1-A + VAD: 1. + +**Table 2c/G.108 – Provisional planning values for the equipment impairment factor ( $I_e$ ) under propagation error conditions, GSM codecs** + +| Codec type | Error pattern | I_e range | +|-------------------|----------------------|-------------------------------| +| GSM-HR | EP 1 | 25...32 | +| | EP 2 | 31...42 | +| GSM-FR | EP 1 | 32...39 | +| | EP 2 | 40...45 | +| GSM-EFR | EP 1 | 15...22 | +| | EP 2 | 26...35 | + +NOTE 1 – The range given results from the difficulties in deriving exact impairment factor values for these conditions. +NOTE 2 – EP 1 is equivalent to 10 dB C/I, EP 2 is equivalent to 7 dB C/I. C/I is the carrier to interference ratio. + +## 7.7 Delay variation versus time + +Packetized transmission systems exhibit variable delay in packet delivery time; this is caused by the fact that different packets carrying speech samples of the same telephone conversation may be transported via distinct routes through the network: details of this effect depend strongly on the specific mechanisms for transport, queuing or prioritization, which may be implemented in such a system. + +Packets which have been transported through a packet based network are collected in a buffer at the receive side. This buffer functions as the instance which re-arranges the timely order of the packets. If the delivery time of a packet exceeds the length of the receive buffer, then this packet "comes too late" with respect to the size of this buffer and will be discarded. Hence, the speech carried in this packet is lost for the decoding process. This "packet loss" impacts speech transmission quality. One approach to minimize the percentage of such lost packets is the dynamic adaptation of the length of the receive buffer. + +A receive buffer with adaptive length controls its actual length via its filling level: + +- if the number of packets being at a time within the buffer increases, then the length of the buffer will be increased and at the same time at the output of the buffer short pause sequences from the original signal will be dropped in order to drain the buffer with a faster rate; +- if the number of packets being at a time within the buffer decreases, then the length of the buffer will be decreased and at the same time at the output of the buffer short pause sequences will be additionally inserted into the original signal in order to drain the buffer with a slower rate. + +Consequently, there will be a variable value of the end-to-end mean one-way delay between the talker's mouth and the listener's ear. It is important to clearly distinguish this effect from other delay variation discussions which refer to network internal processes, only. The impact of an end-to-end delay variation, as explained in this subclause, is strongly dependant on the length of the dropped or inserted pieces of pauses; further emphasis rests on the correct implementation of the dynamic adaptation processes, e.g. the insertion of pieces of pauses into a syllable will have more serious impact than the insertion of pieces of pauses into a pause sequence. + +The parameter of end-to-end delay variation is independent of the use of Voice Activity Detection (VAD) devices (see 7.10.6). + +The impact of end-to-end delay variation on speech transmission quality is for further study and not included in the algorithm of the E-Model. + +## 7.8 Advantage factor A + +The "advantage factor A" represents an "advantage of access", introduced into transmission planning for the first time via the E-Model (Recommendation G.107 [3] and [59]). This factor enables the planner to take into account the fact that customers may accept some decrease in quality for access advantage: e.g. mobility or connections into hard-to-reach regions. This value can be used directly in conjunction with all other impairment values and as an input parameter to the E-Model. Provisional A values are listed in Table 3, which has been taken from Recommendation G.107 [3]. + +**Table 3/G.108 – Provisional examples for the advantage factor A** + +| Communication system example | Maximum value of A | +|-----------------------------------------------------------------------------|--------------------| +| Conventional (wirebound) | 0 | +| Mobility by cellular networks in a building | 5 | +| Mobility in a geographical area or moving in a vehicle | 10 | +| Access to hard-to-reach locations, e.g. via multi-hop satellite connections | 20 | + +These values are provisional since they have not been confirmed by subjective investigations to date. Therefore, the advantage factor A should be used with care and with respect to the business interest of the private network customer, where users may judge specific advantages in telecommunication with criteria other than those used in the usual private domain. The use of the advantage factor in transmission planning of private networks and the selected values are subject to the planner's decision; however, the values in Table 3 should be considered as the maximum upper limit for A. + +## 7.9 Limits at the public/private interface with respect to echo + +Transmission planning for private networks, as described in this Recommendation is primarily directed to the performance of the private network; i.e. intended to provide acceptable speech quality for private network users. A private network, however, can also be the source for signal reflections from 2-wire terminations or network elements, connected through hybrids to a digital network interface point. In conjunction with the mean one-way delay of the public network connection, this may result in a talker echo impairment for the talker at the far (public network) end. + +Although the basic planning principles of this Recommendation are based on end-to-end transmission performance, the interface between the private network and a public network needs additional control with respect to certain parameters. This is for consistency with related standards for these interfaces. Because these standards differ between Europe and North America, each is treated separately here. + +### 7.9.1 Public/private network interfaces – Europe + +The guidelines are derived from reference [54], where limits are given for the so-called "Network Connection Point" (NCP), to control echo in national calls where no echo cancellers are inserted. Summarizing the content of [54], the following limits at the NCP should be taken into account with respect to transmission planning: + +| | | +|---------------------------------------|-----------------------------------------------------------------| +| Minimum Send Loudness Rating | +7 dB | +| Minimum Receive Loudness Rating | +3 dB | +| Echo loss (digital in to digital out) | > 24 dB (long term objective)
> 20 dB (short term objective) | +| Mean one-way delay of the echo path | < 5 ms | + +These values are generally considered as being based on a maximum mean one-way delay of 25 ms for the whole echo path, with 15 ms for the path within the (transit) public network and 5 ms each for the paths within the (terminating) private networks (for more details see Reference [54]). The long term objective for the total TELR as the sum of SLR, RLR and echo loss EL is 34 dB. Assuming no further impairments, these values of 25 ms and TELR = 34 dB will result in an E-Model Rating $R = 77.1$ (see Figure 10), which falls into the "medium" category of speech transmission quality according to Table 1. + +If the limit of 5 ms within the private network is exceeded and/or a TELR of 34 dB cannot be met, echo control devices, even for national calls within European countries, should be used to assure adequate echo protection for the far-end talker. For configurations wherein values of the mean one-way delay and the TELR are close to, or likely to exceed the above limits, a calculation using the E-Model is recommended. + +### 7.9.2 Public/private network interfaces – North America + +In North America, guidelines for the interface between a public and a private network are given in [44], wherein the assumed nominal characteristics for access lines between customer equipment and the public network are defined. + +Analogue access lines are assumed to be terminated by equipment having nominal characteristics given in Table 4 (see [41]). An appropriate range is given to account for wide variations in telephone sets and loops. The ERL given in Table 4 is estimated as that achievable for analogue access lines in the spectrum of digital network configurations in North America. + +**Table 4/G.108 – Assumed analogue access characteristics** + +| Parameter | Nominal (dB) | Range (dB) | +|--------------|--------------|--------------------| +| SLR | +11 (Note 1) | +19 to +6 (Note 2) | +| RLR | –3 (Note 1) | –8 to +2 (Note 2) | +| ERL (Note 3) | $\mu = 14$ | $\sigma = 3$ | + +NOTE 1 – SLR and RLR are specified at the loop interface at the DEO. These values are predicated on a 9 kft (2.7 km), 26-gauge (0.4 mm) cable loop and a 48-volt power supply. +NOTE 2 – Variations in both telephone sets and access lines contribute to these values. +NOTE 3 – ERL values shown above refer to loss across the hybrid with the access line terminated at the NI in a standard impedance (typically 600 $\Omega$ in series with 2.16 $\mu\text{F}$ ), and do not include any network losses. + +Digital access lines are assumed to be terminated with digital telephone sets conforming to specifications in [42] as provided in Table 5, or other digital terminal equipment having equivalent characteristics. + +**Table 5/G.108 – Assumed digital access characteristics for lines terminated in digital sets** + +| Parameter | Desired (dB) | Required (dB) | +|-----------|--------------|---------------| +| SLR | 8 | 5 to 14 | +| RLR | 2 | –1.5 to 5.5 | +| TCLw | >45 | $\geq 40$ | + +Digital access lines between the PSTN and a PBX/Private Network interface should follow the guidelines of Table 5; recognizing, however, that this is strongly dependent on the loss plan and echo loss provisions of the PBX, as given in [40]. + +Reference [44] recommends that any new system, network or component that, by itself, adds more than 2.5 ms mean one-way delay should provide echo cancellation. Otherwise, degradation of transmission quality would occur. The rationale for this guideline is that when a new digital technology becomes part of an end-to-end connection in the PSTN, in general, the connection may not contain an echo canceller, or the capability of the echo canceller is unknown. + +## 7.10 Parameters not directly subject to transmission planning + +As mentioned in the beginning of clause 7, certain transmission parameters can be neglected for the benefit of simplification in the calculation of speech quality. Although these parameters had previously been used in transmission planning and, in some cases, are input parameters to the E-Model, the assumption of an environment in both the private and public domains which embodies mainly digital transmission and digital connection elements will decrease the influence of these specific parameters. + +### 7.10.1 Frequency response + +In analogue transmission, impairment due to the *frequency response* of unloaded cable sections and other connection elements needed to be controlled. For the purpose of this Recommendation, it is assumed that analogue routing via unloaded cable sections within the private network occurs only in lower portions of the hierarchy and generally, only on short or medium line lengths. Furthermore, the effect of frequency slope is usually equalized by pre-emphasis of the frequency response of most analogue telephone sets. The E-Model does not cover this impairment. + +### 7.10.2 Circuit noise + +Another parameter that needs to be considered only in specific applications is *circuit noise*. Sources for circuit noise historically were associated with analogue networks using FDM systems and with certain switching systems; these have been subject to "noise-planning". However, when switching equipment (PBXs) and transmission elements within the private network are designed according to international and national standards with respect to noise (e.g. Recommendations Q.551 [36], Q.552 [37], Q.553 [38], Q.554 [39], [40] or [52] for switching systems), its influence to speech quality is negligible. Only in special cases, e.g. interference to analogue cable sections by power lines or other noise sources, should noise be part of planning calculation. For such cases, the E-Model provides for the input of the circuit noise parameter ( $N_c$ ), with a value referred to the 0 dBr-point. For further information, see clause 9. + +### 7.10.3 Listener echo + +Likewise, impairments caused by *listener echo* are included in the calculation algorithm of the E-Model, with the corresponding input parameters *Weighted Echo Path Loss (WEPL)* and *round trip delay (Tr)* of a 4-wire loop, when part of the connection. The effect of listener echo generally depends on the same connection characteristics and network elements as the effect of talker echo. Therefore, if sufficient control of talker echo in a connection is provided, the listener echo can be assumed to be of minor influence. + +### 7.10.4 Sidetone + +Other parameters included in the E-Model may have important influence to speech quality but are usually not subject to planning. This is generally the case for parameters associated with various analogue and digital telephone sets. The relevant parameters for telephone sets are the *Sidetone Masking Rating (STMR)*, and the *Listener Sidetone Rating (LSTR)*, in conjunction with the "D factor", a value related to the design of the handset. Analogue telephone sets, STMR, and to some extent LSTR, depend on the degree of matching between the balance impedance of the telephone circuit and the input impedance of the terminating line interface in the PBX, in conjunction with the impedance of the ports interfacing 2-wire facilities. + +To simplify the task of transmission planning, and to keep these impairments as low as possible, it is recommended that telephone sets in private networks comply with relevant international or national standards concerning transmission parameters. Furthermore, it is recommended that analogue interfaces are designed to an appropriate "impedance strategy". For more information refer to Supplement 31 to G-series Recommendations [14], [40] or [52] and to A.1 and A.4 in Reference [59]. + +### 7.10.5 Room noise + +One other parameter, not usually subject to transmission planning, is *room noise*. Under certain unusual environmental conditions, room noise, at both the talker and listener sides, may have a significant impact on speech quality. The E-Model includes room noise, separately for the send and receive sides as a source for impairments. The room noise, in as normal an office environment as can be assumed for the business domain of private networks, can be expected in a range of 30 to 50 dB(A). Within this range, any impairment encountered due to room noise will be minor, therefore both parameters $P_s$ and $P_r$ can be set to their default values in the E-Model. However, in specific applications with a significantly higher ambient noise level, such as telephone sets located in factory environments, an average value established by noise level measurements should be used as an input parameter to the E-Model. + +### 7.10.6 Comfort noise, voice activity detection + +*Noise contrast* occurs when background noise is interrupted due to digital speech processing, such as echo cancellation using centre clippers, and *voice activity detection* (silence removal). *Comfort noise* is noise that can be introduced to mask the negative effects of noise contrast. Recommendations on *noise contrast* limits, and comfort noise values are for future study. + +For *comfort noise* insertion, some digital cellular systems (e.g. GSM) use an approach where noise parameters are extracted at the sending end and transmitted to the receiving end at a low bit rate. It is then possible to reconstruct (to a good approximation) the background noise. This approach should provide superior subjective speech transmission performance for circuits using *voice activity detection* and comfort noise insertion. The *voice activity detectors* and comfort noise generators, described in Annex B/G.729 and Annex A/G.723.1, both operate in this fashion. + +The best (subjective) performance will be realized when the noise inserted at the receiving end matches, as closely as possible, the background noise at the sending end. The following comments on Comfort Noise Generators (CNGs) can be made: + +- the noise used should match the background noise, both in frequency content and level; +- level of the inserted noise should match that of the background noise; appropriate level measurements and adjustments should be done using dBm0p; +- the time course of changes in the level of the inserted noise should match, as closely as possible, the level changes that occur in the background noise. + +Nevertheless, it should be observed that these types of artificially generated noise, as stated previously, are of a substantially different nature than traditional noise-related parameters which are taken account of by the E-Model. Hence, noise figures provided in conjunction with CNG or VAD systems should never be used as input values for E-Model calculations in order to avoid wrong results. + +### 7.10.7 Forward error correction + +In the event that a digital sequence, which has been transmitted does not (or with errors) arrive at the destination, it is a common method for data transmission to notify the sender of this fact and to initiate a second transmission of the same sequence. For telephony speech transmission this method is not feasible, because this would result in excessive end-to-end delay and thus decrease the speech transmission performance (see further explanations in 7.7 on delay variation versus time). + +One approach of replacing missing or errored speech samples is to use the last speech sample (received earlier) again. This method is very effective for waveform codecs (e.g. Recommendation G.711 [15]) where speech samples are of very short length (e.g. 125 µs) and are proportional to the actual waveform of the speech signal. However, this method fails for non-waveform codecs (e.g. Recommendation G.723.1 [17]) where one frame comprises a much longer part of the speech signal (e.g. 30 ms) and depending on the specific type of low bit-rate codec one missing frame at the receiver may cause an errored output of the decoder for a time lasting several times as long as the speech sample contained in one frame. + +Hence, in conjunction with low bit-rate coding schemes (which are in most cases non-waveform codec types) *Forward Error Correction* (FEC) should be used in order to improve end-to-end speech transmission quality. This leads to increased robustness of the codec with respect to channel errors. Proper robustness is required especially for radio sections and IP based transport facilities, because there it is more likely that speech samples are lost or being discarded than in traditional wire-bound systems. FEC may appear in different realizations in various parts of a connection: + +- 1) as internal part of the coding algorithm (e.g. Recommendation G.729 [22]); +- 2) as an algorithm in conjunction with the radio section (e.g. GSM); + +- 3) in connections involving an IP based network (in the InterWorking Function (IWF) unit at the interface to the PSTN/ISDN or in the IP terminal). + +The basic principle of FEC is simply that, that a frame or a packet contains, beside the distinct speech sample, additional information, which is related to earlier or later speech samples. At the receive side this additional information can be used to re-construct missing or errored speech samples. + +The principle of FEC can be explained with a very plain and simplified example: + +- In a packet based network, each packet may contain two consecutive speech samples and each speech sample may be contained in two consecutive packets (e.g. packet {n} contains speech samples {m} and {m+1}, packet {n+1} contains speech samples {m+1} and {m+2}, and so forth). In this case, even if every second packet will be lost or discarded, all speech samples will be available without errors at the receive side. + +In practice, however, FEC algorithms are very complex, in order to cope with the real channel error behavior and the transport capacity. With respect to the first and second type of FEC, as listed afore, their properties are part of the respective Standards and their effectiveness are included in the equipment impairment factor ( $I_e$ ) for such codecs under errored conditions (see Tables 2b and 2c). + +For the third type of FEC no standardized method is available up to now. Thus, the effect of FEC of the third type evades practical transmission planning approaches; this is for further study. + +## 7.11 Synchronization + +Proper synchronization design is part of the network planning strategy, because synchronization impairments will affect the quality of the calls: the networks should be synchronized as defined in the series of documents [55], Annex F of [40] and ISO/IEC 11573 [61], in order to achieve the slip rate objectives defined in Recommendation G.822 [25]. + +Synchronization impairments result in slips, creating various degradations. This is especially important in connections where echo cancellers are deployed, because echo cancellers need, for reasons inherent to echo cancellation techniques, a time-invariant near-end echo path in order to work properly (see Note 2 of 3.2/G.165 [11]). Slips in the echo path of the echo canceller will create phase shifts, which lead to periodic divergence/reconvergence of the echo canceller. This is a new kind of impairment that is not addressed in this Recommendation and by the current version of the E-Model. + +# 8 Calculation of end-to-end parameters + +As described in clause 9 in more detail, the use of the E-Model for planning calculations requires the correct handling of this model to avoid wrong results. The E-Model is based on a basic reference configuration, separated into a send side and a receive side with a "virtual centre" referred to as a 0 dBr-point. One of the main tasks when using the E-Model is to transform the different end-to-end connections into a format which is similar to the basic reference configuration of the E-Model. In this context it is necessary to: + +- define the virtual centre to be used as the 0 dBr-point; +- perform "pre-calculations" for the different parameters; and +- clearly identify existing echo paths. + +The following subclauses provide guidance for these calculations for all main parameters which are subject to planning. + +## 8.1 Overall loudness rating + +Considering the basic principle of this Recommendation, that transmission planning is based only on end-to-end performance, any impairment caused by a too high or a too low volume of a connection is consequently related only to the Overall Loudness Rating (OLR). In practice, however, it is necessary to separate the OLR at the 0 dBr-point into a Send Loudness Rating (SLR) and a Receive Loudness Rating (RLR) for both transmission directions, since the E-Model requires these input parameters separately. To obtain the correct input values SLR and RLR for the E-Model, a "pre-calculation" of these parameters is necessary. The first step, then, is to define the 0 dBr-point in the considered configuration, to be followed by the summation of all SLR/RLR values of the respective telephone sets and all distributed losses along the connection on each side of the 0 dBr-point. + +For the definition of the 0 dBr-point in a given configuration, a point should be defined where the speech signal is in a standard 64 kbit/s frame and in an 8 bit PCM A-law or $\mu$ -law form. In most of the network applications described in this Recommendation, the digital interface between the private network and a public network will serve as the 0 dBr-point. + +The principles of pre-calculation are demonstrated with the configuration shown in Figure 13. + +![Figure 13/G.108 – Reference connection for the calculation of SLR and RLR](a161a2bbb4d830e847ccb4f44b7e41a9_img.jpg) + +The diagram illustrates a reference connection for calculating Send Loudness Rating (SLR) and Receive Loudness Rating (RLR). It is divided into two sides by a '0 dBr point' at the Network Connection Point (NCP) or NI. + +- Side A (Private network):** + - An analogue telephone set is connected via an extension line with a loss of 3 dB to PBX A. + - The telephone set has SLR = 3 dB and RLR = -8 dB. + - Inside PBX A, a hybrid circuit inserts a receive loss of 7 dB. + - The transmission element B between PBX A and transit PBX C is a digital facility with bit-transparent routing. + - Transit PBX C inserts a digital loss pad of 4 dB in each direction. + - The receive loudness rating at the NCP/NI is labeled as RLRA. +- Side B (Public network national long distance path):** + - The path continues from the NCP/NI through PBX D and PBX E to a far-end termination. + - Within PBX E, the 4-wire/2-wire conversion with A/D-D/A conversion inserts a receive loss of 7 dB. + - The far-end termination is an analogue telephone set connected via a subscriber line with a loss of 4 dB. + - The combined loudness values for the far-end termination are SLR = 7 dB and RLR = -4 dB. + - The send loudness rating at the NCP/NI is labeled as SLRB. + +Labels at the top indicate SLRA for Side A and RLRB for Side B. A reference number T1211160-99 is shown at the bottom right. + +Figure 13/G.108 – Reference connection for the calculation of SLR and RLR + +NOTE – The values shown in Figure 13 are for illustration only and do not necessarily reflect actual circuit or loudness values in different regions. + +**Figure 13/G.108 – Reference connection for the calculation of SLR and RLR** + +In the private network, an analogue telephone set with SLR = 3 dB and RLR = -8 dB is connected via an analogue extension line with a loss of 3 dB to PBX A. The hybrid in the extension line circuit inserts a loss of 7 dB in the receive direction. The transmission element B between PBX A and transit PBX C is a digital facility (leased line or tie trunk) with bit-transparent routing. Transit PBX C inserts a digital loss pad of 4 dB in each direction. The path within the public network for a national long distance call provides a fully digital routing between the private network interface (NCP or NI), and the local office E, at the far end. Within this local office, the 4-wire/2-wire conversion in conjunction with an A/D-D/A conversion inserts a receive loss of 7 dB. The far-end termination is formed by a single analogue telephone set connected to the local office E via an analogue subscriber line with a loss of 4 dB. The combined loudness values for the far-end termination (SLR and RLR of the set and cable loss) are assumed to be SLR = 7 dB and RLR = -4 dB. + +For this configuration, the 0 dBr-point can be defined at the Network Connection Point (NCP) or NI, the interface between private and public network. With reference to the 0 dBr-point, the configuration is divided into a Side A and a Side B (which are not automatically identical with the + +send side and receive side of the E-Model). The summation of SLR/RLR values and circuit losses is performed for both transmission directions so that values for $SLR_A$ , $SLR_B$ , $RLR_A$ and $RLR_B$ are obtained. The four loudness rating values can be calculated as follows: + +### **Side A:** + +| | | Set > 0 dBr-point | 0 dBr-point > Set | +|---------------------------|-----|-----------------------------------|----------------------------------| +| Telephone set | SLR | 3 dB | – | +| | RLR | – | –8 dB | +| Extension line | | 3 dB | 3 dB | +| PBX A | | 0 dB | 7 dB | +| Leased line (tie trunk) B | | 0 dB | 0 dB | +| Transit PBX C | | 4 dB | 4 dB | +| Sum at 0 dBr-point | | SLR_A = 10 dB | RLR_A = 6 dB | + +### **Side B:** + +| | | Set > 0 dBr-point | 0 dBr-point > Set | +|---------------------------|-----|----------------------------------|----------------------------------| +| Far-end termination | SLR | 7 dB | – | +| | RLR | – | –4 dB | +| Local exchange E | | 0 dB | 7 dB | +| Routing in public network | | 0 dB | 0 dB | +| Sum at 0 dBr-point | | SLR_B = 7 dB | RLR_B = 3 dB | + +It is very important to select the correct values as input values for the E-Model from these results (see clause 9). According to the basic principle of the E-Model, the expected quality is calculated as perceived at the receive side, i.e. the customer of the private network is the listener (receive side) and the customer at the far-end termination is the talker (send side). Therefore, the values for the transmission direction from far-end termination to private network should be used as input values to the model: + +$$SLR_B = 7 \text{ dB} \quad RLR_A = 6 \text{ dB}$$ + +The OLR for this transmission direction is: + +$$OLR = SLR_B + RLR_A = 7 \text{ dB} + 6 \text{ dB} = 13 \text{ dB}$$ + +The OLR for the opposite direction is: + +$$OLR = SLR_A + RLR_B = 10 \text{ dB} + 3 \text{ dB} = 13 \text{ dB}$$ + +For the configuration and the values in this example, the OLR is equal in both transmission directions. Therefore, in this case, the additional calculation for the transmission direction from private network telephone to the far-end termination is generally not necessary with respect to impairments due to OLR. + +However, in the exceptional case that the telephone set in the private network is located in a noisy environment, both transmission directions should be considered and calculated separately. Assuming a measured mean room noise of 65 dB(A) at the location within the private network and the default value for the room noise of 35 dB(A) at the far-end termination the calculation procedure is as follows: + +For the direction from the far-end termination to the private network (private network is the receive side) the values for $SLR_B$ and $RLR_A$ should be used and the parameter $P_r$ (room noise at the receive side) is set to 65 dB(A) with $P_s$ (room noise at the send side) remaining at the default value. For all other parameters at their default values, the E-Model Rating $R$ for this direction (perceived quality of the private network customer) is calculated with $R = 66.9$ . + +For the direction from the private network to the far-end termination (receive side at far-end termination) the values $SLR_A$ and $RLR_B$ are used, the parameter $P_s$ is set to 65 dB(A) and $P_r$ remains at the default value. The E-Model Rating $R$ in this direction is $R = 57.1$ , a result which shows that the impairment of high room noise is different to the listeners at both ends. + +When calculating the loudness rating values, it is advisable to also control the requirements at the NCP (NI) with respect to the $SLR$ and $RLR$ of the private network as described in 7.9. For the example of Figure 13, the NCP is identical with the defined 0 dBr-point, therefore the calculated values for $SLR_A$ and $RLR_A$ at the 0 dBr-point can be used for assessing compatibility with the NCP/NI requirements. In this example, the requirements of 7.9.1 (for the European approach) with the given minimum values of $SLR = 7$ dB and $RLR = 3$ dB are met. + +## 8.2 Talker echo + +For the impairment due to echo effects, the given configurations should be investigated with respect to sources for signal reflections, usually hybrids. For E-Model calculations of the perceived quality, two input parameters must be pre-calculated: + +- mean one-way delay $T$ in ms; +- Talker Echo Loudness Rating (TELR) in dB. + +For more information about the effect of echo, see Recommendations G.126 [8] and G.131 [9]. + +For the investigation of echo (especially in conjunction with the E-Model), it is important to recognize that the parameter TELR is a function of the $SLR$ and $RLR$ of the **talker's** telephone according to the formula: + +$$TELR = SLR + EL + RLR$$ + +where $EL$ is the (weighted) echo loss of the echo path. Thus, the $SLR$ and $RLR$ values of the telephone set are included in two different input parameters of the E-Model; as part of the TELR, and as direct input of $SLR$ and $RLR$ for calculations of other impairments. + +NOTE – The use of $SLR$ and $RLR$ in two separate pre-calculations is based on the principle and the algorithm of the E-Model as described in detail in Recommendation G.107 [3]. In most applications, the model will be used in conjunction with a computer program. The handling of the different input values, however, may deviate between such programs and the E-Model. Therefore, it is necessary to clearly identify what input values are required and in which form they are entered in the specific program to avoid getting wrong results. For example, if the program does automatic pre-calculations based on connection variables affecting $SLR$ and $RLR$ , both the loudness rating and echo effect pre-calculations are subject to changes in these variables. For further information see clause 9. + +Note also, that impairments caused by talker echo are referred to the talker at the "receive" side, in accordance with the principles of the impairment factor method and the E-Model. This should be taken into account carefully when selecting parameters as input for the E-Model for each particular configuration. + +In some applications, the reference connection considered may contain more than one echo path. Subclauses 8.2.1, 8.2.2, and 9.5 provide guidance for the calculation procedure for single as well as for multiple echo path cases. + +### 8.2.1 Calculation for connections with one echo path + +The following calculation example is based on the reference connection shown in Figure 14. A digital telephone set with $SLR = 7$ dB and $RLR = 3$ dB and with a mean one-way delay of 1.5 ms is connected to PBX A in the private network. PBX A is connected to the transit PBX C via a digital tie trunk or leased line B with bit-transparent routing and a mean one-way delay of 2 ms. Transit PBX C inserts a digital pad of 3 dB in each transmission direction for voice calls. PBXs A and C contribute with a mean one-way delay of 1 ms each. + +The public network provides fully digital routing up to the far-end local office E where a hybrid is a source for signal reflections, and therefore part of the echo path. The far-end termination is assumed to be a single analogue telephone set. For the echo calculation, the values of this far-end termination are not relevant, since it is not part of the echo path. Based on information provided by the public network provider, the mean one-way delay within the public network for a national long distance call is assumed to be 10 ms. The hybrid in the local office E is assumed to have an average (weighted) echo loss (EL), of 24 dB, including a loss of 7 dB in the receive (towards the end termination) path. + +![Diagram of a reference connection for echo calculations with one echo path. The diagram shows a 'Private network' section on the left and a 'Public network national long distance path' section on the right, ending at a 'Far end termination'. A 'Digital telephone' is connected to PBX A. The echo path is highlighted with a dashed line and arrows. Key parameters shown include SLR = 7 dB, RLR = 3 dB, 3 dB digital pads at PBX C, EL = 24 dB at the hybrid in PBX E, and mean one-way delays of 1.5 ms, 1 ms, 2 ms, 1 ms, and 10 ms.](8d66c9c295023a1380f9986d3663bb1e_img.jpg) + +The diagram illustrates a reference connection for echo calculations. It is divided into three main sections: 'Private network', 'Public network national long distance path', and 'Far end termination'. + +In the 'Private network' section, a 'Digital telephone' is connected to PBX A. The telephone has an $SLR = 7$ dB and $RLR = 3$ dB, and a mean one-way delay of 1.5 ms. PBX A has a mean one-way delay of 1 ms. A digital tie trunk or leased line B connects PBX A to PBX C, with a mean one-way delay of 2 ms. PBX C has a mean one-way delay of 1 ms and includes 3 dB digital pads in both transmission directions. + +The 'Public network national long distance path' has a mean one-way delay of 10 ms and contains PBX D. + +The path ends at the 'Far end termination' (PBX E), which contains a hybrid. The hybrid has an average (weighted) echo loss (EL) of 24 dB, which includes a 7 dB loss in the receive path towards the termination. The return path from the hybrid shows an $RLR = -4$ dB, a 4 dB loss, and an $SLR = 7$ dB. + +A dashed line with arrows indicates the 'Echo path', starting from the telephone, through the network elements, reflecting at the hybrid, and returning. A horizontal line at the bottom indicates the 'Mean one-way delay in ms' for each segment. + +Diagram of a reference connection for echo calculations with one echo path. The diagram shows a 'Private network' section on the left and a 'Public network national long distance path' section on the right, ending at a 'Far end termination'. A 'Digital telephone' is connected to PBX A. The echo path is highlighted with a dashed line and arrows. Key parameters shown include SLR = 7 dB, RLR = 3 dB, 3 dB digital pads at PBX C, EL = 24 dB at the hybrid in PBX E, and mean one-way delays of 1.5 ms, 1 ms, 2 ms, 1 ms, and 10 ms. + +Figure 14/G.108 – Reference connection for echo calculations with one echo path + +A clear identification of the echo path should be the first step of every calculation. For the example illustrated in Figure 14, the echo path consists of the digital telephone set (where the talker echo is perceived), the complete path via transmission and switching elements between that telephone set and local office E, the Echo Loss (EL) in local office E, and the return path. This echo path is identified in Figure 14. + +The second step is to calculate the two relevant input parameters of the echo path for the E-Model: the mean one-way delay $T$ , and the TELR. It is important to note that only the "one-way" delay serves as the input value for the model, even though the echo signal is delayed by twice the value of that delay (assuming the same connection path for both directions). + +Once the echo path is defined, the first input value for the calculation, the mean one-way delay $T$ is the sum of the (one-way) delay values of the different elements. For the example in Figure 14 above, this sum calculates to $T = 15.5$ ms. The second input value to the E-Model, the TELR, is calculated as the sum of all losses along the whole echo path (both directions) including the SLR and RLR of the (talker's) telephone set. For the example above, this value is calculated as $TELR = 40$ dB. + +Based on an E-Model calculation using $T = 15.5$ ms and $TELR = 40$ dB as input values, the configuration of Figure 14 yields an E-Model Rating $R = 85.8$ , a value which falls into the "high" category of speech transmission quality according to Table 1. + +### 8.2.2 Calculation for connections with two echo paths + +Due to increasing digitalization in public and private networks, configurations with more than one echo path will occur with less and less likelihood and such configuration should be avoided in network design. Nevertheless, the following gives an example of how to handle such a configuration; it is derived from the configuration of Figure 14 and is based on the use of a cordless telephone, connected to an analogue port at PBX A. The additional delay introduced by a cordless telephone termination is not negligible, hence the cordless telephone forms a separate echo path together with the end-to-end echo path via the public network (which is the same as in the configuration of Figure 14). This reference connection with its two effective echo paths is illustrated in Figure 15. In such a configuration the talker may be disturbed by two different echoes with different volume and different delay. + +![Figure 15/G.108 – Reference connection for echo calculations with two echo paths. The diagram shows a network configuration with a Private network and a Public network. The Private network includes a Mobile part (Cordless telephone) and a Fixed part (PBX A). The Fixed part contains an Echo Controller (EC) and a Switching System (SS). The Public network is a national long distance path. The Far end termination is shown on the right. The diagram illustrates two echo paths: Echo path 1 (from the cordless telephone) and Echo path 2 (from the public network). Key parameters shown include: 14 (Fixed part), 7 dB (attenuation at PBX A), 3 dB (attenuation at PBX B), 3 dB (attenuation at PBX C), 10 (Mean one-way delay in ms), EL = 24 dB (echo loss), RLR = -4 dB (return loss ratio), 4 dB (attenuation at PBX D), and SLR = 7 dB (sending loss ratio).](8f7c0bf0c75a31fee6b0c7392ff57c39_img.jpg) + +Figure 15/G.108 – Reference connection for echo calculations with two echo paths. The diagram shows a network configuration with a Private network and a Public network. The Private network includes a Mobile part (Cordless telephone) and a Fixed part (PBX A). The Fixed part contains an Echo Controller (EC) and a Switching System (SS). The Public network is a national long distance path. The Far end termination is shown on the right. The diagram illustrates two echo paths: Echo path 1 (from the cordless telephone) and Echo path 2 (from the public network). Key parameters shown include: 14 (Fixed part), 7 dB (attenuation at PBX A), 3 dB (attenuation at PBX B), 3 dB (attenuation at PBX C), 10 (Mean one-way delay in ms), EL = 24 dB (echo loss), RLR = -4 dB (return loss ratio), 4 dB (attenuation at PBX D), and SLR = 7 dB (sending loss ratio). + +**Figure 15/G.108 – Reference connection for echo calculations with two echo paths** + +To determine the expected overall quality, a special application of the E-Model needs to be derived here, because the E-Model does not currently accommodate and calculate two simultaneous impairments due to talker echo. The E-Model does not allow a simple addition of these two pairs of T and TELR, resulting in new input parameters. The fact, that two echo sources are present simultaneously is more complex and needs further investigation. Special psychoacoustic effects, such as masking of one echo by the other, may influence the perception of quality. + +For this situation, it is generally recommended to follow a three-step approach. The first step is to consider the impairments due to echo only, calculating the two echo paths 1 and 2 separately: i.e. for each echo path, the relevant parameters of mean one-way delay, T, and TELR should be determined independently, assuming the other echo path as not existing. In the second step, the calculated impairment-values for the two echo paths should be combined with a specific formula (not provided by the E-Model). Finally, this result is combined with the result of E-Model calculations for all other impairment parameters (e.g. Ie value for ADPCM) in this configuration. This procedure and how to handle the E-Model in this special application is described in more detail in 9.5 together with general guidance for the application of the E-Model in planning practice. The following paragraphs describe how to determine the parameters TELR and T for the two echo paths. + +For the cordless telephone in Figure 15, the fixed part (base station) should provide a 4-wire/2-wire conversion for the connection to an analogue 2-wire interface. That hybrid is then a source for signal reflections and forms echo path 1 together with the mobile part via the air interface. When determining the relevant parameters mean one-way delay T and TELR of this echo path, parameters specific to the cordless telephone, should be taken into account. + +Cordless telephones conforming to [50] and [53] insert an additional mean one-way delay of approximately 14 ms between acoustic interface of the portable part and the network interface of the fixed part (see Table A.1). This amount of delay is likely to cause echo effects in many applications. Therefore, this configuration requires precautions to suppress the reflected signal, via the use of an Echo Canceller (EC), together with a Soft Suppressor (SS). More detailed information about echo control in specific cordless telephones is provided in Annex C. + +When determining the TELR of this echo path 1, these "integrated" echo control devices must be taken into account. Figure 16 shows in more detail the relevant components for echo control in a terminal, most of which reside in the fixed part. Inside the fixed part a virtual "reference point" is defined, where the speech signal, which is transcoded into ADPCM for transmission via the air path, is again present in standard PCM format. + +![Figure 16/G.108 – Details inside a cordless telephone with respect to echo control. The diagram shows the signal flow from the mobile part to the fixed part and back. The mobile part contains a microphone (A), a digital-to-analog converter (D/A), a PCM encoder (P C M), and an ADPCM decoder (A D P C M). The fixed part contains an ADPCM encoder (A D P C M), a PCM decoder (P C M), an Echo Canceller (EC), and a Soft Suppressor (SS). The reference point is located at the interface between the fixed part and the network. The diagram includes various gain and loss values: SLR = 3 dB and SLR = 7 dB for the send path; RLR = 3 dB and RLR = -8 dB for the receive path; EL = 18.5 dB, EL = 9.5 dB, and EL = 3 dB for echo loss; ELE > 6.5 dB for echo loss enhancement; a_s = -4 dB and a_R = -11 dB for level adjustments; and a_BRL = 18 dB for balance return loss. The mean one-way delay is 14 ms. The diagram is labeled T1211190-99.](fe25bbee6685ab20f50ffc80c3feddd8_img.jpg) + +Figure 16/G.108 – Details inside a cordless telephone with respect to echo control. The diagram shows the signal flow from the mobile part to the fixed part and back. The mobile part contains a microphone (A), a digital-to-analog converter (D/A), a PCM encoder (P C M), and an ADPCM decoder (A D P C M). The fixed part contains an ADPCM encoder (A D P C M), a PCM decoder (P C M), an Echo Canceller (EC), and a Soft Suppressor (SS). The reference point is located at the interface between the fixed part and the network. The diagram includes various gain and loss values: SLR = 3 dB and SLR = 7 dB for the send path; RLR = 3 dB and RLR = -8 dB for the receive path; EL = 18.5 dB, EL = 9.5 dB, and EL = 3 dB for echo loss; ELE > 6.5 dB for echo loss enhancement; a\_s = -4 dB and a\_R = -11 dB for level adjustments; and a\_BRL = 18 dB for balance return loss. The mean one-way delay is 14 ms. The diagram is labeled T1211190-99. + +Figure 16/G.108 – Details inside a cordless telephone with respect to echo control + +Per [50] the system is adjusted to $SLR = 7$ dB and $RLR = 3$ dB referred to this reference point. These loudness rating values would not meet requirements when connected to a 2-wire analogue interface. In the example of Figure 14, values of $SLR = 3$ dB and $RLR = -8$ dB are assumed to meet such requirements (other national/regional requirements may apply). The hybrid circuitry inside the fixed part (at the right side of the reference point in Figure 16) not only provides the necessary A/D-D/A and 4-wire/2-wire conversion, but also includes, in its analogue part, a level adjustment of $a_s = -4$ dB in sending direction and $a_R = -11$ dB in the receive path in order to meet the required $SLR/RLR$ values at the 2-wire interface. + +The calculation of TELR for echo path 1 should be performed in several steps. For the hybrid, an average balance return loss $a_{BRL} = 18$ dB can be assumed if correct impedance matching, using complex balance networks, is provided. For the entire hybrid circuitry, this balance return loss is reduced by the sum of the adjustments $a_s$ and $a_R$ , resulting in a net echo loss (EL) of 3 dB. To improve this low echo loss, an Echo Canceller (EC), is used, compensating partly for the reflected signal. This is expressed in terms of an Echo Loss Enhancement (ELE), which, in the DECT standard, requires $> 6.5$ dB. The echo loss is thus increased to $(3 + 6.5)$ dB $= 9.5$ dB. A further improvement is available by the insertion of a Soft Suppressor (SS), in the receive path (towards the telephone) inside the fixed part. This SS inserts an additional loss of 9 dB (the DECT standard suggests 9 to 12 dB) whenever a signal is detected in the send path. The resulting value of + +$(9.5 + 9) \text{ dB} = 18.5 \text{ dB}$ , together with the loudness values of $\text{SLR} = 7 \text{ dB}$ and $\text{RLR} = 3 \text{ dB}$ , leads to a TELR of 28.5 dB for echo path 1. The mean one-way delay of echo path 1 is 14 ms. + +NOTE – Although the values of SLR and RLR are referred to the reference point, they can also be assumed at the left Uniform PCM (UPCM) point in Figure 16 since there is no additional loss inside the UPCM path. It should also be noted, that the SS is only enabled if a signal in the send path is present, which is valid for the consideration of talker echo, but it is disabled during listening when the talker is silent. Therefore, the RLR values in Figure 16 are shown for a disabled SS. + +For echo path 2, the calculation of the relevant values for mean one-way delay T and TELR is similar to the calculation in 8.2.1 but with different values. Summing up the values for delay for each network element along echo path 2, as shown in Figure 15, the mean one-way delay of echo path 2 is $T = 28 \text{ ms}$ . + +The calculation of TELR in echo path 2 requires care to avoid wrong results. The send path from the microphone of the portable part via the hybrid circuitry in the fixed part can be summarized as $\text{SLR} = 3 \text{ dB}$ (Figure 16). The echo path continues via the hybrid circuitry of PBX A (0 dB), the digital pad in PBX C (3 dB), to the hybrid circuitry of local office E, with an echo loss of 24 dB. + +The return path includes the digital pad in PBX C (3 dB), and the hybrid circuitry in PBX A (7 dB), and the receive path of the cordless telephone which is shown in Figure 16 as $\text{RLR} = -8 \text{ dB}$ . However, this RLR value must be adjusted by the 9 dB loss of the SS (which is enabled during talking and thus is also a factor for echo path 2), i.e. for the purpose of calculating the TELR, $\text{RLR} = (-8 + 9) \text{ dB} = +1 \text{ dB}$ . Thus, the sum for echo path 2, using the values as shown in Figures 15 and 16, is $\text{TELR} = (3+3+24+3+7+1) = 41 \text{ dB}$ . Note, that the echo canceller in the fixed part does not affect echo path 2 since the processing capability of the echo canceller (which is generally about 4 ms) with respect to the echo path delay is much less than the connection delay. + +The relevant values for the two echo paths are as follows: + +- echo path 1            TELR = 28.5 dB            T = 14 ms; +- echo path 2            TELR = 41.0 dB            T = 28 ms. + +## 8.3 Transmission time in echofree connections + +As noted in 7.3, very long delay may cause impairments other than echo. Connections which exhibit a significant delay impact the perceived speech transmission quality even if they are designed "echofree" with perfect echo cancelling. For planning purposes, transmission time usually needs to be considered only for long national (e.g. in North America) or international connections or when routing via a satellite link, but also national or internal connections within the network under consideration may be affected, if modern signal processing devices like low bit-rate codecs are inserted. For the use in the E-Model, the absolute delay ( $T_a$ ), in ms should be calculated as the sum of all mean one-way delay values of the different network elements throughout the entire connection. It should be noted that all elements, including the telephone sets at both ends, should be considered independent of any echo sources such as hybrids and inserted echo cancelling devices. Specific transmission elements or connection elements or even complete routings may have different values of delay in the two transmission directions. In these cases the arithmetic mean of both values should be used. + +## 8.4 Quantization distortion units + +The E-Model requires this input parameter in terms of the number of Quantization distortion units (qdu) as described in 7.5. The complete process of coding (analogue to digital conversion) and decoding (digital to analogue conversion) according to the coding laws (A-law or $\mu$ -law) as defined in Recommendation G.711 [15] is considered as one qdu. When performing the summation for the entire connection each pair of "coder" and its subsequent "decoder" should be clearly identified. + +For coding laws other than those contained in Recommendation G.711 [15] (e.g. ADPCM), the impairments due to distortion should not be expressed in terms of qdu, but rather as the equipment impairment factor ( $I_e$ ) (see 8.5). When elements which effect the coding (such as digital loss or gain pads, echo cancelling devices or (digital) conference circuits) are part of the connection, a standard value of 0.7 qdu for each such element should be used in the calculation. + +NOTE – While some Recommendations still contain qdu value assignments for ADPCM (and some other low bit-rate codecs) the use of such qdu values for transmission planning is no longer recommended. + +If the routing of a connection is fully digital, a minimum of 1 qdu should be taken into account, regardless of whether the coder/decoder is located in the digital telephone set or in the line card for the connection of an analogue telephone set. In the E-Model the default value for this parameter is already set to qdu = 1 and should not be modified to qdu = 0 in an fully digital environment. + +## 8.5 Equipment impairment factor + +As described in 7.6, modern coding laws will cause impairments due to distortions. Contrary to the standard PCM coding and decoding according to the A-law or $\mu$ -law (Recommendation G.711 [15]), these impairments are expressed in terms of "equipment impairment factor" ( $I_e$ ), instead of Quantization distortion units (qdu). The $I_e$ factors for different coding laws and operating rates are given in Table 2a. For planning practice, only the algebraic sum of all $I_e$ values along the investigated connection should be calculated and inserted into the E-Model as an input value. However, it is very important to clearly identify, using the reference configuration, the actual location of the coder and decoder of such a low bit-rate section, since such a low bit-rate section may include several transmission elements and connection elements. A connection may also include more than one section using the same or different types of such low bit-rate coding, which must be considered for calculation. + +## 8.6 Equipment impairment factor for codecs under conditions of packet loss + +Provisional values for the equipment impairment factor for codecs under conditions of packet loss are provided in Tables 2a and 2b. Even if those values are very pre-mature they do give an estimate of the high impact this parameter has on speech transmission quality. Depending on the dynamic nature of most packet based transmission systems, today, the difficulty for the transmission planner will be that there is no network with fixed percentage of packet loss; rather the percentage of packet loss may be variable and depend on other factors like network mechanisms or network load. + +Thus, the equipment impairment factor for codecs under conditions of packet loss evades practical transmission planning approaches; this is for further study. + +## 8.7 Delay variation versus time + +The impact of delay variation versus time on end-to-end speech transmission performance, as described in 7.7, depends strongly on whether the dynamic adaptation of the receive buffer length is correctly implemented in the equipment and then this parameter can than be neglected in most cases; this is for further study. + +# 9 Application of the E-Model in planning practice + +## 9.1 General + +The basic planning principles recommended in this Recommendation are based on the use of the E-Model (see clause 6) for the performing of planning calculations which provide a prediction of the expected quality for a specified configuration. This planning methodology is a departure from earlier transmission planning guidelines which, particularly for private networks, were based on the + +assignment of limits for the pertinent transmission parameters. Therefore, some introduction and guidance on the application of these new principles and the use of the computational model are given in this subclause. + +A detailed description of the E-Model and its associated algorithm is contained in Recommendation G.107 [3]. It should be noted that, to avoid wrong results, the use of this E-Model requires some understanding about the basic reference configuration and of the different input parameters. This is covered in detail in 9.2, 9.3 and 9.4. Subclause 9.5 covers the special configuration with two echo paths. + +Because of the number and complexity of the E-Model formulas, the calculations will generally be performed by computer programs. Nevertheless, it is important for the user to be familiar with the program itself, including the handling of input parameters and the limits for the program's application. Information on this topic is provided in 9.6. + +The E-Model includes a variety of transmission parameters; however, not all of them are varied for planning purposes (see 7.10). These parameters should be set to, and remain at a default value (which is not necessarily zero) during the calculation run. Furthermore, the algorithm of the E-Model is based on the results of subjective tests, in which the different parameters have been varied only within specific ranges. When using the model with input parameters outside of these ranges, the results obtained will not have been validated. Therefore, the use of such values should be avoided. Subclause 9.7 lists all default values and the valid ranges for each parameter. + +## 9.2 Reference configurations + +For the comprehension of the basic principles of the E-Model, it is useful to construct a basic reference configuration of an end-to-end telephone connection in which all transmission parameters with influence on the perceived speech quality are presented. This reference configuration, shown in Figure 17, is basically divided into a "send side" and a "receive side" with a virtual centre referred to as a "0 dBr-point". One of the most important assumptions in the model is, that the perceived quality is referred to the "receive side", i.e. the listener during a call, and to that same side with respect to impairments encountered during talking, such as sidetone, room noise and echo effects. The basic reference configuration in Figure 17 includes a "4-wire loop" to recognize the impairments of talker echo and listener echo; impairments which are only of minor influence in a fully digital (4-wire) connection. + +![Diagram of the basic reference configuration of the E-Model showing send and receive sides with various transmission parameters.](7722d62e33dcc894cc8555e9474c5606_img.jpg) + +The diagram illustrates the basic reference configuration of the E-Model, divided into a "Send side" (left) and a "Receive side" (right) with a "0 dBr-point" in the center. The send side includes a talker with parameters $D_s$ (sidetone) and $P_s$ (room noise). The receive side includes a listener with parameters $D_r$ (sidetone), $P_r$ (room noise), and $STMR$ (sidetone-to-masking ratio). The central part of the diagram shows a "4-wire loop" with a "WEPL" (Wideband Echo Path Loss) block. Parameters shown include $OLR$ (Overall Loss Ratio), $SLR_s$ (Send Loss Ratio), $RLR_R$ (Receive Loss Ratio), $Tr$ (Talker Echo), $N_c$ (Noise), $(SLR_R)$ (Receive Loss Ratio), $T$ (Transmission Loss), $T_a$ (Talker Echo), and $qdu, I_e, A$ (Quality, Impairment, and Adaptation factors). The listener's perceived quality is indicated as "Connection quality as perceived at receive side". The diagram is labeled "T1211200-99" at the bottom right. + +Diagram of the basic reference configuration of the E-Model showing send and receive sides with various transmission parameters. + +Figure 17/G.108 – Basic reference configuration of the E-Model + +In the process of network planning, it is desirable to identify a "most critical" connection for investigation and planning and to designate that connection as the reference connection for that network. This reference configuration, which should contain all relevant transmission elements and connection elements, is useful for identifying and calculating the total amount of any specific parameter in the end-to-end connection. In most situations, however, this reference configuration will deviate more or less from the basic reference configuration of the E-Model. To minimize errors when entering values of different parameters into the E-Model, including results from pre-calculations, it is recommended to transform the reference configuration of the investigated connection into a form as nearly identical as possible to the basic E-Model configuration shown in Figure 17. + +The following figures provide guidance for transforming actual planning configurations into E-Model-related configurations. For each of these "working" configurations which are classified as 2-wire/2-wire, 2-wire/4-wire, 4-wire/2-wire or fully 4-wire structures, the appropriate treatment for the applicable parameters is described. + +In Figure 18, the same 2-wire/2-wire structure is shown as in the basic E-Model configuration, but here divided into different sections for better comparison with the actual connection. With respect to the virtual centre of the connection and related to the 0 dBr-point, the figure is divided into a "Side A" identical with the "send side" and a "Side B" identical with the "receive side". Both sides are terminated with analogue telephone sets A and B, each with its individual loudness rating values SLR A, RLR A and SLR B, RLR B. + +The factors $D_s$ at the send side and $D_r$ at the receive side depend on the handset design and are usually not subject to planning. These factors should be set to their default values for calculation. The parameters, Sidetone Masking Rating (STMR) and Listener Sidetone Rating (LSTR), are assumed to have a fixed relation with the D-factor in the form: + +$$LSTR = STMR + D$$ + +and thus influence the perceived quality only at the receive side. + +![Figure 18/G.108 – Working configuration for 2-wire/2-wire connections. The diagram shows a transmission path between Telephone A (Side A, Send side) and Telephone B (Side B, Receive side). The path is divided into sections A1, A2, A3, B3, B2, and B1. Key components include: Telephone A with parameters Ds, Ps, SLR A, RLR A; Telephone B with parameters Pr, SLR B, RLR B, LSTR, STMR, TELR, Dr. The network elements include TBRL(w) at points A2 and B2, WEPL between A3 and B3, and a 0 dBr point (Nc) at the center. Horizontal dimension lines indicate SLR_S, RLR_R, T, Ta, and qdu, le. A small note 'T1211210-99' is at the bottom right.](21327313f7b18a481da0c87a6472a80d_img.jpg) + +Figure 18/G.108 – Working configuration for 2-wire/2-wire connections. The diagram shows a transmission path between Telephone A (Side A, Send side) and Telephone B (Side B, Receive side). The path is divided into sections A1, A2, A3, B3, B2, and B1. Key components include: Telephone A with parameters Ds, Ps, SLR A, RLR A; Telephone B with parameters Pr, SLR B, RLR B, LSTR, STMR, TELR, Dr. The network elements include TBRL(w) at points A2 and B2, WEPL between A3 and B3, and a 0 dBr point (Nc) at the center. Horizontal dimension lines indicate SLR\_S, RLR\_R, T, Ta, and qdu, le. A small note 'T1211210-99' is at the bottom right. + +Figure 18/G.108 – Working configuration for 2-wire/2-wire connections + +Parameters STMR, LSTR and D are usually not subject to planning and should be kept at their default values except for specific telephone circuit arrangements, impedance provisions, or non-standard handsets designs. + +The room noise ( $P_s$ ), at the Send Side may influence the signal to noise ratio as perceived at the receive side, while the room noise ( $P_r$ ), at the receive side may decrease the perceived quality via the sidetone path. However, for telephone sets in normal office environments, the values for room noise can remain at their default values. + +The Talker Echo Loudness Rating (TELR), as one of the input parameters to the E-Model, needs specific attention and is described in more detail in 9.3. + +Sections A1 and B1 of Figure 18 should be understood as the analogue interconnection between the telephone set and the switching equipment where the 4-wire/2-wire conversion is provided. These sections may consist of transmission elements (e.g. unloaded cables) and switching elements (e.g. a PBX with an analogue switching matrix). Therefore, for A1 and B1, mainly loss values need to be calculated. + +Sections A2 and B2, normally components (e.g. subscriber line card, trunk card) of switching elements, are shown in detail, since they include the 4-wire/2-wire conversion circuits (hybrids) and the loss pads (R in receiving, and T in sending, direction). In conjunction with the degree of matching (TBRL), these components have a significant influence on speech quality. + +The Terminal Balance Return Loss (TBRL), shown in Figure 18 expresses this degree of impedance matching between the balance network of the hybrid and the impedance of the terminating 2-wire section. The weighted Terminal Balance Return Loss [ $TBRL(w)$ ] is not a direct input parameter for the E-Model, but is required for pre-calculations of TELR. + +Finally, sections A3 and B3 in Figure 18 represent the digital part of the connection between the hybrids, including the A/D- and D/A-conversion, and the point in the configuration which has been declared as the 0 dBr-point. The interface between different networks (e.g. public and private) may also be included in sections A3 and B3. These sections may contain several switching elements and transmission elements, including digital loss or gain pads, low bit-rate coding, etc. which contribute parameters such as loss, delay and distortions. In the pre-calculation, these impairment parameters should be accounted for. + +The 4-wire loop composed of sections A2, A3 and B2, B3 may contribute to listener echo impairments, characterized by the parameters Weighted Echo Path Loss (WEPL), and round trip delay ( $T_r$ ). $T_r$ can be calculated as the sum of all delay values (both directions), mostly in sections A3 and B3, while WEPL is sum of all losses and gains inserted in sections A3 and B3, combined with the TBRL and the losses of the R- and T-pads associated with the hybrids in A2 and B2. + +![Figure 19/G.108 – Working configuration for 4-wire/2-wire connections. The diagram shows a network configuration between Side A (Send side) and Side B (Receive side). Side A includes a digital telephone (Ds) with parameters Ps, SLR A, RLR A, and (TCLw). Side B includes a 2-wire telephone (Telephone B) with parameters RLR B, SLR B, Pr, and Dr. The network is divided into sections A1, A2, A3, B3, B2, and B1. Key components include SLR_S, RLR_R, WEPL, and a 0 dBBr point (Nc). Horizontal lines at the bottom indicate delays T, Ta, and qdu, Ie. A reference code T1211220-99 is present at the bottom right.](cbab05075b3d7dc0d27c4cbb0c914a94_img.jpg) + +Figure 19/G.108 – Working configuration for 4-wire/2-wire connections. The diagram shows a network configuration between Side A (Send side) and Side B (Receive side). Side A includes a digital telephone (Ds) with parameters Ps, SLR A, RLR A, and (TCLw). Side B includes a 2-wire telephone (Telephone B) with parameters RLR B, SLR B, Pr, and Dr. The network is divided into sections A1, A2, A3, B3, B2, and B1. Key components include SLR\_S, RLR\_R, WEPL, and a 0 dBBr point (Nc). Horizontal lines at the bottom indicate delays T, Ta, and qdu, Ie. A reference code T1211220-99 is present at the bottom right. + +**Figure 19/G.108 – Working configuration for 4-wire/2-wire connections** + +The working configuration shown in Figure 19 can be used for connections with a 4-wire termination (digital telephone set) at the send side and a 2-wire termination at the receive side. In this configuration, the values for SLR A and RLR A are referred to the digital telephone A. Here, an additional parameter, the weighted Terminal Coupling Loss (TCLw) (of the digital telephone set) must be considered. The TCLw characterizes the coupling between receiver and microphone (including any acoustical, electrical and structure borne coupling paths) from which a possible source for signal reflection may arise (see also Recommendation G.100 [1] and Recommendation G.122 [7]). + +TCLw, which is not a direct input value to the E-Model, should be included in the pre-calculation of the TELR value to define impairments due to echo perceived at the receive side. TCLw should also be part of the pre-calculations for WEPL. With respect to talker echo and listener echo, the TCLw in this configuration replaces the echo loss (TBRL and associated R- and T-pads) of the hybrid in section A2 of Figure 18. It should be noted that the mean one-way delay, T, in Figure 19 includes section A1 and the telephone, in contrary to the configuration in Figure 18 where the echo path with respect to the talker at the receive side is terminated in section A2. + +All other discussions and explanations given for the working configuration in Figure 18 are also valid for this configuration. + + + +## 9.3 Handling of the input parameters + +To obtain correct results, the specific structure of the algorithm and the handling of the different input values of the E-Model should be carefully considered. This is particularly true for Loudness Rating (LR) values. The E-Model algorithm expects, as input, the total value for $SLR_S$ , covering the send side and a total value for $RLR_R$ , for the receive side, both defined between the acoustical interface (microphone or receiver) and the 0 dBr-point. With respect to Figures 18 through 21, these values are calculated as follows: For the send side, the sum of $SLR_A$ of telephone A and all sending direction loss values in sections A1, A2 and A3. For the receive side, the sum of all receive direction losses of sections B3, B2, B1 and the loss values $RLR_B$ of telephone B. It is highly desirable to verify that the telephone set LR values are consistent with applicable standards via accepted measurement methods, such as Recommendation P.79 [29]. + +For the investigation of the transmission direction from A to B the values $RLR_A$ and $SLR_B$ are not relevant. + +Besides applicable to the input parameters $SLR_S$ and $RLR_R$ , loudness rating values are also part of the parameters $TELR$ , $STMR$ and $LSTR$ . The values for $STMR$ and $LSTR$ indeed depend on the $SLR$ and $RLR$ of the telephone set. For practical planning purposes, a fixed value for both sidetone parameters, in conjunction with the $SLR$ and $RLR$ , as stated by the manufacturer of the telephone sets, can be used; thus, the input parameters $STMR$ and $LSTR$ are set to their default values and only modified if, in case of analogue telephone sets, the likelihood of a significant impedance mismatch needs to be considered. + +NOTE – For telephone sets with volume control in send and/or in receive direction in the handset mode, the $SLR$ and $RLR$ for the default setting of the volume control and the corresponding values for $STMR$ and $LSTR$ , as stated by the manufacturer should be used for planning purposes. + +To include the impairments due to talker echo, the algorithm of the E-Model expects two parameters, the mean one-way delay ( $T$ ), in ms along the echo path and the Talker Echo Loudness Rating ( $TELR$ ), of the echo path. It is very important, to note that the talker echo is referred to the Receive side. As explained in 8.2, the value for $TELR$ is obtained in a pre-calculation according to the basic formula: + +$$TELR = SLR + EL + RLR$$ + +where $SLR$ and $RLR$ are loudness rating values of the receive side telephone set, i.e. $SLR_B$ and $RLR_B$ , with respect to Figures 18 through 21. Although $RLR_B$ is already part of the basic input value $RLR_R$ , the formulas of the E-Model do not provide an automatic inclusion of the loudness rating values, i.e. $RLR_R$ and $TELR$ need to be pre-calculated separately using the same value for $RLR_B$ . + +The Echo Loss ( $EL$ ), in the above formula is the sum of all losses along the echo path, i.e. in sections B1, B2, B3, A3 and A2 of the working configurations in Figures 18 and 20 and additionally in section A1 of Figures 19 and 21. The losses in sections B1, B2, B3 and A3 should be identified and included for **both** transmission directions; e.g. the loss of section B1 in Figures 18 and 19 is included twice within the echo path. For section A2 of Figures 18 and 20, the R- and T-pads and the $TBRL(w)$ of the terminating hybrids are included in $EL$ ; likewise the $TCLw$ of the digital sets in Side A in Figures 19 and 21. It is absolutely necessary to use the "weighted" value for the $TBRL$ . + +The definition of the circuit noise parameter ( $N_c$ ), can lead to wrong results if this input value to the E-Model is not included correctly. The E-Model algorithm assumes any noise sources to be defined by noise levels as they would appear at the 0 dBr-point. Usually, circuit noise is no longer a major factor in a digital environment and its specification can be neglected in most applications; i.e. the default value of $-70\text{ dBm}0p$ can be used. However, in an analogue environment, such as in sections A1 or B1 of Figure 18, noise may arise, e.g. due to longitudinal interference into telephone + +cables from power lines. If such noise sources cannot be neglected, the noise level should be pre-calculated into an equivalent value at the 0 dBr-point. + +Example: Measured longitudinal interference into a cable in section A1 of the working configuration in Figure 18 will result in a transversal noise level of $-50$ dBmp at the interface between sections A1 and A2. If the T-pad in the hybrid of section A2 has a loss of 3 dB, the noise level is reduced by this pad accordingly, resulting in a value of $-50$ dBmp $- 3$ dB $= -53$ dBm0p at the 0 dBr-point. + +## 9.4 Interpretation of the results + +As described in clauses 6 and 7 in detail, this Recommendation and the recommended planning principles are based on the equipment impairment factor method in conjunction with the use of the E-Model (Recommendation G.107 [3]). The result of any planning investigation with respect to the perceived quality is presented in terms of the E-Model Rating R. + +As stated in clause 6, provisions should be made that, in addition to the E-Model Rating R the specific results for $I_d$ , $I_s$ and $I_e$ are available during transmission planning. This is useful to recognize and to identify the different contributions of each category of impairment when investigating solutions towards an improved quality. + +## 9.5 Application of the E-Model for configurations with two echo paths + +As mentioned in 8.2.2, a special procedure applies when a configuration with two effective echo paths is to be calculated with the E-Model. Since the algorithm of the E-Model does not handle two impairments of talker echo, simultaneously contributing to the overall quality, this special procedure described below is necessary. + +In general, the procedure is derived from the same basic principle of the E-Model, namely that impairments are additive on a psychological scale. This is also assumed for the two different echo effects with different values for the mean one-way delay, and the TELR, as given for the example in Figure 15, together with further impairments in this configuration. However, a simple addition of the two impairments, caused solely by the two different echo effects, would not be correct. Assuming that for a human listener the quality perception and its judgement is influenced more by the echo with the higher impairment value and that also some effects of masking may occur, a square root addition is recommended. + +While the final result of any calculation with the E-Model will be the E-Model Rating R (see clause 6), as a partial result in the course of this calculation the impairment value $I_d$ summarizes all impairments caused by delay and echo. For the consideration of impairments due to two echo paths, a pre-calculation with $I_d$ values is necessary. + +As a first step, the impairments $I_{d1}$ for echo path 1 and $I_{d2}$ for echo path 2 due only to talker echo are calculated (assuming that the computer program in use is providing the separate impairment values). This calculation is performed separately for each echo path, assuming that all other parameters are set to their default values and only values for T and TELR for the considered echo path are distinctly specified as input values to the E-Model. The two results for $I_{d1}$ and $I_{d2}$ are then combined to a total (sum-) value $I_d$ for both impairments using the following equation: + +$$I_d = \sqrt{I_{d1}^2 + I_{d2}^2}$$ + +This value of $I_d$ now represents all impairments due to the talker echo effects of both echo paths. + +In the second step, all other impairments effective in the configuration considered are included, setting all relevant parameters to their actual values. It is important to note that, in this second calculation, the input values for the parameters mean one-way delay (T), and TELR should be set to + +their default values ( $T = 0$ ms, $TELR = 65$ dB). The resulting E-Model Rating $R'$ of this second calculation is then combined with the impairment value for the two echo paths, $Id$ as follows: + +$$R = R' - Id$$ + +For the actual calculation of this configuration with two effective echo paths, a decision about the working configuration (see 9.2) to be used in the first step is not necessary. Since all parameters with the exception of $T$ and $TELR$ are set to their default values, a specific configuration is not relevant. + +The configuration of Figure 15 will now be used to illustrate the above principles. + +The following list reflects the input parameters $T$ and $TELR$ for both echo paths, which have already been calculated in 8.2.2 and the respective impairment values $Id_1$ and $Id_2$ for the two echo paths which can be calculated with the algorithm of the E-Model (see 3.4/G.107 [3]) setting all input parameters, except $T$ and $TELR$ , to their default values (see Table 6). + +| | TELR/dB | T/ms | Id | +|-------------|----------------|-------------|-----------| +| echo path 1 | 28.5 | 14 | 17.3 | +| echo path 2 | 41 | 28 | 8.1 | + +The results for $Id_1$ and $Id_2$ are now combined to one value using the square root relation: + +$$Id = \sqrt{Id_1^2 + Id_2^2} = \sqrt{17.3^2 + 8.1^2} = 19.1$$ + +For the final calculation, including all other impairments without talker echo effects, one of the working configurations presented in 9.2 needs to be selected for the correct identification of the different parameters and their use as input parameters to the E-Model. For the configuration in this example, the working configuration for 2-wire/2-wire connections as shown in Figure 18 is selected as most appropriate. + +Comparing this working configuration with the actual configuration as shown in Figure 15, the telephone B at the receive side in Figure 18 represents the complete cordless equipment, including the fixed part. The far-end termination is represented by telephone A. The 0 dBr-point can be defined between public and private network; i.e. at the digital interface between exchanges C and D. The loudness rating values for the entire cordless system (telephone B) and the far-end termination (telephone A) are used to define the SLR and RLR of the connection with respect to the receiving side, B. + +The SLR of the send side referred to the 0 dBr-point is equal to the value $SLR = 7$ dB of the far-end termination, since no other gain or loss is inserted in the path between the telephone and the 0 dBr-point. The RLR for the receive path between the 0 dBr-point and the cordless equipment includes the 3 dB digital pad in exchange C, the loss of 7 dB associated with the hybrid of exchange A and the RLR of $-8$ dB (see Figure 16) of the complete cordless system, resulting in $RLR = 2$ dB. Thus, the RLR can remain at its default value during calculation. It is important to note that, for this calculation, wherein the listening conditions are judged, the Soft Suppressor (SS) should be assumed to be disabled. The other impairment in this connection is the use of 32 kbit/sec ADPCM coding within the cordless system which should be taken into account with the input parameter for $I_e$ set to a value of 7 according to Table 2a. + +The effects of listener echo and of absolute delay will be of minor influence in this configuration; nevertheless the corresponding parameters $Tr$ , $WEPL$ and $Ta$ are included in the following calculation for tutorial purposes and for completeness. + +When the configuration in Figure 15 is examined with respect to a possible source for impairments due to listener echo, it is seen that there is a 4-wire loop in the public/private network formed by the hybrids in the exchanges A and E. A second 4-wire loop is theoretically formed within the cordless equipment between the hybrid in the fixed part and the $TCLw$ of the portable part. + +However, as explained in 7.10, the influence of listener echo is usually negligible as long as there is sufficient control of the talker echo. Calculations for the configuration and values of Figure 15 result in values for the round-trip delay ( $T_r$ ) = 28 ms and for the weighted echo path loss $WEPL$ = 54 dB. + +As explained in 7.3, the absolute one-way delay ( $T_a$ ) causes major impairments only when the delay exceeds 150 ms, i.e. the value for the absolute delay ( $T_a$ ) = 28 ms, for the configuration of Figure 15 will have no influence on the result. + +The calculation for the second step can now be performed with the calculated input values for $SLR$ = 7 dB, $I_e$ = 7, $T_r$ = 28 ms, $WEPL$ = 54 dB and $T_a$ = 28 ms, while all other parameters, especially $T$ and $TELR$ (the influence of the two pairs of $T$ and $TELR$ for the two echo paths has been considered in the first pre-calculation) remain at their default values. This results in an E-Model Rating $R'$ = 87.4. The final result of this calculation, the E-Model Rating $R$ , is then obtained by combination of the pre-calculated results $R'$ and $I_d$ : + +$$R = R' - I_d = 87.4 - 19.1 = 68.3$$ + +This result falls into the "low" category of speech transmission quality according to Table 1. This result of low speech transmission quality seems to be surprising, considering that configurations like the one of Figure 15 are in common use (the configuration is nearly identical with a cordless telephone directly connected to a public network) without users' complaints. The major factor contributing to the E-Model Rating $R$ is echo path 1 with $I_{d1}$ = 17.3, i.e. the echo path via the hybrid of the cordless telephone. For the suppression of this echo, an echo canceller can generally be assumed to be provided. The minimum value of echo loss enhancement, for example, is 6.5 dB. In practice, however, higher values can be expected which, for planning calculations, should be made available by the supplier of the cordless telephone set. Nevertheless, this example supports the recommendation to connect, whenever possible, cordless telephones to the switching equipment via a digital interface, since then only echo path 2 is effective, resulting in an E-Model Rating of $R$ = 79.3, which is at the upper end of the "medium" category of speech transmission quality, being nearly in the "high" category. + +## 9.6 Use of computer programs + +The E-Model, the recommended main tool for all planning purposes in this Recommendation, comprises a number of more or less complex formulas (see Recommendation G.107 [3]). Thus, the planner usually relies on computer programs for performing the calculations needed. Irrespective of whether such programs are developed by the planner, or if programs available from other sources are used, it is strongly recommended that the user be fully familiar with the use of this program and the limits of its application. + +Computer programs may assist the planner with a variety of features, such as the handling of input parameters, necessary pre-calculations, storing of often-used configurations, etc. As described in 9.3, the correct handling of loudness rating values in conjunction with the necessary pre-calculations is very important and can be supported by such programs. However, it is recommended to provide additional control of all input parameters after performing a pre-calculation run. + +Programs may also provide a structure for the input of parameter values as shown in the working configurations of Figures 18 through 21. In this case, pre-calculations for specific sections need to be performed outside the program. + +NOTE – If, for the benefit of simplification, certain parameters are not considered during transmission planning, the use of computer programs may deliver slightly different results, depending on the concept of such programs. If, for example, the parameter $WEPL$ is not considered, because it can be neglected, a computer program with numerical input, will perform the calculations with $WEPL$ and $T_r$ at their default values, while a computer program with graphical input (e.g. based on the working configurations, Figures 18 through 21) will perform the calculation with the actual values (slightly deviating from default) for $WEPL$ and $T_r$ . This fact is important for the correct interpretation of calculation results gained by different programs. + +Although the recommended planning principle in this Recommendation is based on the E-Model Rating R as the outcome of calculations, the E-Model also includes the capability to calculate the corresponding values for MOS, %PoW and %GoB (see clause 6). Thus, computer programs may provide the results of a calculation in these different presentations. The analysis of results in terms of MOS, %PoW and %GoB requires some knowledge and experience with the underlying subjective tests. Therefore, the final decision about an investigated configuration should be based on the results of calculations in terms of the E-Model Rating R and the corresponding guidelines given in clause 6. + +When planning telephone networks with respect to the expected speech quality, as perceived by the user, connections identified as the most critical ones should be used as reference configuration and should be investigated with the E-Model. Such configurations will generally be characterized with one specific set of input parameters, leading to a single value of E-Model Rating R to assess the connection quality. Most of the computer programs, however, will also have a feature to vary one or more input parameters in a given range during the program run and to display the results in the form of graphs or tables. Those features can be helpful to obtain an overview of the influence of different transmission parameters on speech quality and may enable the planner to optimize certain parameters such as loss, though, for practical purposes of planning, those features are not absolutely necessary. + +In general, computer programs for E-Model calculations should meet the following minimum requirements: + +- Control of all actual parameter values should be possible. +- Input of parameter values outside of the permitted range should be refused (or at least indicated). +- If a program also provides the input parameter Overall Loudness Rating (OLR), as the sum of $SLR_S$ and $RLR_R$ and the feature to vary this OLR, the variation of $SLR_S$ and $RLR_R$ should be performed identically; i.e. increasing or decreasing both by the same steps, half of the OLR-steps each. +- The result should also furnish the specific values of the delay impairment factor ( $I_d$ ), the simultaneous impairment factor ( $I_s$ ), and the equipment impairment factor ( $I_e$ ); it should be noted, that for the calculation of two simultaneous echo paths as described in 9.5 this is absolutely indispensable. + +The correctness of calculations according to the algorithm of the E-Model should be verified; e.g. by using all default values as explained in the following subclause. An additional check, using the parameter settings and the corresponding results as given in the planning examples of Annex B, may also be performed. + +## 9.7 Default values and parameter ranges + +The E-Model is based on several transmission parameters. Not all of them are varied during the application for planning calculations, consequently each parameter influences the final result. Therefore, it is absolutely necessary to keep those parameters, which are not specifically addressed or defined in a specific configuration, at their default value. When using computer programs, it is strongly recommended to verify the parameter setting before starting a new calculation run. + +The definition of the default values for the E-Model is based on a compromise between a setting that is equivalent to the optimum quality and realistic values for some parameters. Depending on the region of interest, the $SLR_S$ and $RLR_R$ values may deviate by 1 dB from their optimum value to be in accordance with requirements in regional standards for digital terminals. Such standards also provide the basis for the default values of the parameters STMR, LSTR and D. The number of qdu is set to 1 instead of 0 since, in a fully digital connection, a minimum of one PCM coding/decoding process is involved even if low bit-rate coding is used which itself shall only be included into the calculation as an $I_e$ value. + +As stated in 9.1, the algorithm of the E-Model is based on the results of subjective tests, varying each different parameter only within specific and realistic range. The setting of a parameter outside this range should be avoided, since the result of calculations is no longer validated. Table 6 gives all default values and the recommended range for each of the parameters. The parameters should be viewed as related to the basic or working reference configurations as shown in Figures 17 through 21. + +If all input parameters of the E-Model are set to the default values as listed in Table 6 the result for the E-Model Rating R in this case is $R = 94.1$ (see Notes). + +NOTE 1 – For the calculations shown in this Recommendation the algorithm of the E-Model has been taken from Recommendation G.107 [3] at the time of publication. In case a later revision of Recommendation G.107 [3] does show a refined version of the algorithm, the value of $R = 94.1$ for all input values default may slightly change. Nevertheless, this Recommendation will still provide valid guidance for tutorial purposes. For actual transmission planning tasks it should, in any case, be referred to the latest version of Recommendation G.107 [3]. + +NOTE 2 – The mathematically accurate value of the E-Model Rating R for all input values default, which is $R = 94.154$ , should be used to clearly identify the correctness of any computer programs in use. For transmission planning purposes, however, it should be considered that the E-Model algorithm relies on subjective test data which, by their nature, are of limited accuracy; hence, depending on the type of actual transmission planning task, the E-Model Rating R should be expressed with no more than one decimal digit, or even as an integer. + +**Table 6/G.108 – Default values and recommended ranges for the parameters** + +| Parameter | Abbr. | Unit | Default value | Recommended range | Notes | +|-----------------------------------------------------------------------|------------------|-------|---------------|-------------------|-------| +| Send Loudness Rating | SLR S | dB | +8 | 0 to +18 | 1 | +| Receive Loudness Rating | RLR R | dB | +2 | –5 to +14 | 1 | +| Sidetone Masking Rating | STMR | dB | 15 | 10 to 20 | 2 | +| Listener Sidetone Rating | LSTR | dB | 18 | 13 to 23 | 2 | +| D-value of telephone, send side | D s | – | 3 | –3 to +3 | | +| D-value of telephone receive side | D r | – | 3 | –3 to +3 | 2 | +| Talker Echo Loudness Rating | TELR | dB | 65 | 5 to 65 | | +| Weighted Echo Path Loss | WEPL | dB | 110 | 5 to 110 | | +| Mean one-way delay of the echo path | T | ms | 0 | 0 to 500 | | +| Round trip delay in a 4-wire loop | Tr | ms | 0 | 0 to 1000 | | +| Absolute delay in echofree connections | T a | ms | 0 | 0 to 500 | | +| Number of Quantization distortion units | qdu | – | 1 | 1 to 14 | | +| Equipment impairment factor | I e | – | 0 | 0 to 40 | | +| Circuit noise referred to 0 dBr-point | N c | dBm0p | –70 | –80 to –40 | | +| Noise floor at the receive Side | N for | dBmp | –64 | – | 3 | +| Room noise at the send side | P s | dB(A) | 35 | 35 to 85 | | +| Room noise at the receive side | P r | dB(A) | 35 | 35 to 85 | | +| Advantage factor | A | – | 0 | 0 to 20 | | +| NOTE 1 – Total values between microphone or receiver and 0 dBr-point. | | | | | | +| NOTE 2 – Fixed relation: $LSTR = STMR + D$ . | | | | | | +| NOTE 3 – This value shall not be modified. | | | | | | + +# 10 Rules for the insertion of echo cancellers + +## 10.1 Introduction + +The increasing digitalization of public and private networks resulted in connections which exhibit substantially higher values of mean one-way delay (e.g. due to signal processing and low bit-rate coding), while nearly all additional loss has disappeared. The assumption of a mainly distance-related delay value is no longer valid. This increases the likelihood of impairments due to echo effects if no arrangements are made in conjunction with careful transmission planning to suppress such effects. More details about the causes and effects of echo and its control are given in Recommendations G.131 [9] and G.126 [8]. + +Control of talker echo caused by hybrids can be achieved in three different ways: + +- Firstly, one could try to reduce or eliminate the reflected signal at hybrids. This method is limited due to the complexities of impedance matching between the hybrid balance network and the 2-wire port. +- Secondly, it is possible to reduce the level of the reflected signal at the talker end through deliberate insertion of loss into the connection. This is a practical solution on many connections; however, since the amount of loss required is proportional to the end-to-end delay, it can result in excessive volume reduction for connections with high delay. Furthermore, loss insertion in a digital connection adds quantizing distortion impairments. +- Finally, the use of echo control devices, as discussed in this clause, is applicable. + +In connections where echo control cannot be achieved by mitigation of the reflection at hybrids or by loss insertion, the deployment of echo cancellers will be necessary. The basic principle of an Echo Canceller (EC) is shown in Figure 22. The received signal from party A is modified by the echo estimator which is synthesizing a replica of the echo path and subtracting this signal from the send path. Since the echo path varies for every connection mainly in loss, delay and phase, the process of converging to the new echo path should be fairly rapid, e.g. well below one second. During break-in and double talk conditions, the echo estimator attempts to adapt to this "new echo signal" and may cause a degradation of speech quality and reduction of cancellation. However, several non-standardized algorithms are used to avoid these effects. + +At the output of the send path ECs may be equipped with an additional unit called Non-Linear Processor (NLP) or centre clipper. The task of this device is to provide a suppression of residual echo levels below a defined threshold. + +![Block diagram of an Echo Canceller (EC) showing the interaction between Party A and Party B. Party A's input (Rin) goes to the Receive path. The Receive path output (Rout) is fed into the Echo estimator. The Echo estimator's output is fed into the Subtractor. Party B's input (Sin) goes to the Subtractor. The Subtractor's output goes to the NLP (Non-Linear Processor). The NLP's output (Sout) is fed back to Party A. The Echo path is shown as a vertical arrow on the left side of the diagram.](dd6c544ab685b25dd17f59456efcfbfc_img.jpg) + +The diagram illustrates the internal structure of an echo canceller. It is divided into two main sections: the 'Send path' and the 'Receive path'. The 'Receive path' takes the input 'Rin' from Party A and produces an output 'Rout' to Party B. This 'Rout' signal is also fed into an 'Echo estimator'. The 'Echo estimator' produces a signal that is fed into a 'Subtractor'. The 'Send path' takes the input 'Sin' from Party B and feeds it into the 'Subtractor'. The 'Subtractor' also receives the output from the 'Echo estimator' and produces an output 'Sout' to Party A. The 'Sout' signal is then processed by an 'NLP' (Non-Linear Processor) block. An arrow labeled 'Echo path' points upwards on the left side, indicating the path of the echo from Party A back to Party B. + +Block diagram of an Echo Canceller (EC) showing the interaction between Party A and Party B. Party A's input (Rin) goes to the Receive path. The Receive path output (Rout) is fed into the Echo estimator. The Echo estimator's output is fed into the Subtractor. Party B's input (Sin) goes to the Subtractor. The Subtractor's output goes to the NLP (Non-Linear Processor). The NLP's output (Sout) is fed back to Party A. The Echo path is shown as a vertical arrow on the left side of the diagram. + +Figure 22/G.108 – Echo canceller + +A minimum echo path loss of 6 dB is a requirement common to all ECs which are designed according to Recommendation G.165 [11] to achieve proper operation. As far as ECs are already designed according to Recommendation G.168 [12] this restriction is no longer necessary. + +Previously, in mostly analogue networks, echo cancellers or echo suppressors according to Recommendation G.164 [10] were used mainly on long transnational or for international connections and the public network operators were responsible for their correct application. In modern networks, additional delay may require the insertion of echo cancellers also on shorter national connections and within private networks. The application of echo suppressors is no longer recommended. + +The location of echo cancellers, if required, in a private network depends on various factors. Echo cancellers can either be used along with the digital interface of a specific switching equipment or transmission element, or may be provided in a pool for a flexible insertion, depending on the type of connection. Specific types of terminals with delay which is not negligible, e.g. wireless telephone terminals, are equipped with integrated echo control devices. This may also be true for systems using low bit-rate coding. + +The following subclauses provide guidance to the planner of private networks on the aspects to be taken into account for the correct use of echo cancellers. It should be noted that these rules relate to additional echo cancellers when the need for such additional echo cancellers is indicated by the results of planning calculation. Integrated echo cancellers in specific equipment are, in most cases, not subject to a planning decision, though their technical characteristics should be considered for the decision on additional devices. + +## **10.2 Characteristics of the echo cancellers** + +The different parameters characterizing the performance of an echo canceller are described in A.1.10. These parameters will be the basis for investigating whether the device is suitable for the designated purpose. The main parameters in this context are the maximum echo path delay to be compensated and the residual echo level. A preference should be given to those echo cancellers, which are in accordance with accepted standards, such as Recommendations G.168 [12] and G.165 [11]. + +## **10.3 Limits for the application of echo cancellers** + +The most important step during planning is the decision whether an echo canceller should be inserted or not. Echo cancellers may, in some situations, cause additional impairments, if they are wrongly inserted or if applied unnecessarily when sufficient echo control is already provided in other networks or network elements. The use of echo cancellers just for "safety reasons" should be avoided. + +Since the amount of impairments due to echo depends on two separate factors, the amount of delay and the volume of the perceived echo, which will vary over a wide range and which are independent from each other, an absolute general rule, e.g. a limit value for the mean one-way delay above which echo cancellers are required, cannot be stated. In Europe, the use of echo cancellers is not required when the mean one-way delay in a private network is less than 5 ms for national calls via public networks with fully digital routing, and a far-end termination consisting of a single configuration (see 7.9.1). Furthermore, if this limit of 5 ms is exceeded, this should not be interpreted in such a way that echo cancellers should then be used automatically. The decision should only be based on the result of the planning with the E-Model. As explained in clause 6, the impairment value ( $I_d$ ), as a partial result in the course of this calculation, summarizes all impairments caused by delay and echo and should be available separately during transmission planning. + +North American echo canceller guidelines are based on [44] which does not provide specific values of end-to-end delays beyond which cancellers should be deployed. However, there is a widely accepted guideline for dealing with incremental delays caused by the introduction of digital + +technology. The guideline is that any new system, network or component that, by itself, adds more than 2.5 ms mean one-way delay should provide echo cancellation. The rationale for this guideline is that when a new digital technology becomes part of an end-to-end connection in the PSTN, in general, the connection may not contain an echo canceller, or the capability of the echo canceller is unknown. + +If, in a given configuration, impairments beside echo are significant then the analysis of the E-Model Rating $R$ and the partial results for the impairment factors $I_s$ , $I_d$ and $I_e$ , should be the primary consideration. For values of E-Model Rating $R \geq 80$ , a sufficient good quality can be expected: i.e. the use of echo cancellers is not necessary. For lower values of E-Model Rating $R$ , a partial result of the E-Model calculations, the impairment factor $I_d$ should be considered. If this impairment factor is in a range of $I_d \geq 20$ , then the insertion of echo cancellers should be further investigated because this will likely result in a quality improvement. As a general rule, the insertion of echo cancellers should be considered during transmission planning, if values of E-Model Rating $R \leq 80$ are obtained from calculation and talker echo is the main impairment. + +## 10.4 Determination of the location + +If planning calculation results suggest the use of an echo canceller, the next task of planning is to investigate the appropriate location for the echo canceller as well as consideration of its properties. Due to the nature of echo effects, this investigation should be performed not only for the private network but also for the far-end talker; i.e. control of echo effects for the far end by the provision of a sufficient echo loss or echo cancelling should be subject to planning as well. + +In a configuration such as shown in Figure 23, the additional delay which requires echo control for this connection is inserted by the private network. Therefore, the private network is responsible for providing the necessary echo cancellers. Furthermore, information about the routings and the types of terminal equipment, which are the factors mainly responsible for the amount of delay, are only available to the private network planner. Therefore, when additional delay will arise in specific configurations within the private network, the decision for, and correct insertion of echo cancellers must be done in the private network domain. + +For delays less than 5 ms within the private network, the requirements as given in 7.9 will provide the necessary echo control for the far-end termination. + +For higher values of delay, however, the use of an echo canceller A for the benefit of the far-end talker besides an echo canceller B for the benefit of the private network talker may be necessary to control echo satisfactorily. This may be the case when for example low bit-rate equipment is used within the network under consideration as shown in Figure 23. + +![Diagram illustrating the application of a pair of echo cancellers (EC A and EC B) within a private network. The diagram shows a Private network (containing EC A and EC B), a Public network, and a Far end termination. EC A is located at the far end termination, and EC B is located within the private network. Arrows indicate the echo paths for each canceller: EC A's path is within the far end termination, and EC B's path extends from the far end termination back through the public network and private network to EC B.](3e20f0289a1945c7c3894f51383d8e37_img.jpg) + +The diagram shows a network configuration with three main sections: Private network, Public network, and Far end termination. On the far left, a handset icon is connected to a box labeled 'EC A'. A curved arrow loops from the output of 'EC A' back to its input, labeled 'Echo path for echo canceller A'. 'EC A' is connected to a box labeled 'Low bit-rate equipment'. This box is connected to a box labeled 'EC B'. A curved arrow loops from the output of 'EC B' back to its input, labeled 'Echo path for echo canceller B'. 'EC B' is connected to a dashed vertical line representing the boundary of the 'Public network'. Inside the 'Public network' section, there is a box representing a switching element. Beyond the public network, another dashed vertical line marks the 'Far end termination', which contains a box with a handset icon connected to it. + +Diagram illustrating the application of a pair of echo cancellers (EC A and EC B) within a private network. The diagram shows a Private network (containing EC A and EC B), a Public network, and a Far end termination. EC A is located at the far end termination, and EC B is located within the private network. Arrows indicate the echo paths for each canceller: EC A's path is within the far end termination, and EC B's path extends from the far end termination back through the public network and private network to EC B. + +EC A Echo canceller for the talker at the far end termination + +EC B Echo canceller for the talker within the private network + +**Figure 23/G.108 – Application of a pair of echo cancellers within the private network** + +For the selection of the appropriate echo cancellers, one of the most important properties to be investigated, is the maximum echo path delay which the canceller is able to compensate for (sometimes called "tail-end delay"). This value should be 6-8 ms higher than the actual total delay (twice the mean one-way delay) of the echo path. As shown in Figure 23, the echo path for EC A (the arrow indicates the direction of the echo path) is formed only by the hybrid within the PBX, i.e. only a short delay to be compensated for, while for EC B, the echo path includes the entire routing via the public network with correspondingly higher values for the delay for EC B to handle. It is important to note that, for the selection of EC compensation requirements, only the delay values for the corresponding echo paths should be taken into account. The portion of delay in the section between the two ECs is not relevant for the control of echo and only becomes important for very high values as part of the total one-way delay ( $T_a$ ), which may cause impairments resulting from excessive absolute delay. + +![Diagram illustrating options for the location of an echo canceller. It shows a private network on the left and a public network on the right, separated by a vertical dashed line. In the private network, a telephone handset is connected to a box containing a hybrid and an echo canceller labeled 'EC-f'. An arrow labeled 'Echo path e.g. delay 4 ms' shows the echo path from the handset, through the hybrid, and back to the handset. The 'EC-f' box is connected to 'Low bit-rate equipment', which is then connected to another box containing an echo canceller labeled 'EC-o'. An arrow labeled 'Echo path e.g. delay 24 ms' shows the echo path from the handset, through the hybrid, the 'EC-f' box, the 'Low bit-rate equipment', the 'EC-o' box, into the public network, and back. The 'EC-o' box is also connected to the public network. A legend at the bottom left defines 'EC-f' as 'Echo canceller at favourable location' and 'EC-o' as 'Echo canceller at optional location'. The text 'T1211270-99' is in the bottom right.](29fbbed4c4aff19e9ac5bf98e0c9b24d_img.jpg) + +Diagram illustrating options for the location of an echo canceller. It shows a private network on the left and a public network on the right, separated by a vertical dashed line. In the private network, a telephone handset is connected to a box containing a hybrid and an echo canceller labeled 'EC-f'. An arrow labeled 'Echo path e.g. delay 4 ms' shows the echo path from the handset, through the hybrid, and back to the handset. The 'EC-f' box is connected to 'Low bit-rate equipment', which is then connected to another box containing an echo canceller labeled 'EC-o'. An arrow labeled 'Echo path e.g. delay 24 ms' shows the echo path from the handset, through the hybrid, the 'EC-f' box, the 'Low bit-rate equipment', the 'EC-o' box, into the public network, and back. The 'EC-o' box is also connected to the public network. A legend at the bottom left defines 'EC-f' as 'Echo canceller at favourable location' and 'EC-o' as 'Echo canceller at optional location'. The text 'T1211270-99' is in the bottom right. + +**Figure 24/G.108 – Options for the location of an echo canceller** + +As a general rule an echo canceller should be inserted as close as possible to the echo source. Thus, the location for EC A as shown in Figure 23, associated with the hybrid, can be considered as the most favourable one. However, other locations may also be considered as illustrated in Figure 24 where the EC (for echo control benefiting the far end) is inserted at the PBX which provides access to the public network. + +This solution has the advantage that the number of necessary EC devices is reduced due to a more centralized location. Also the automatic insertion of echo cancellers in only those connections which are routed to/from the public network via a low bit-rate equipment may be easier to handle when the echo control is located at a position EC-o as shown in Figure 24. On the other hand, for the position EC-f in Figure 24, echo cancellers with less stringent requirements can be used since the echo path delay is lower. Furthermore, the position EC-o does not meet the requirement for a linear echo path as described in A.1.10 since the (non-linear) low bit-rate equipment is part of the echo path. + +For the planning of long-distance (e.g. via an interexchange carrier in N.A.) or international connections, the provision of echo cancellers within the public network can generally be assumed. For such configurations, it should be investigated whether the use of an additional echo canceller within the private network is really necessary. For a connection as shown in the example of Figure 25, the echo path comprises the routing via the public network (local or national) and the private network with its terminating hybrid. The mean one-way delay of the public network is + +assumed to be 8 ms and that of the private network 10 ms. The echo canceller EC-pu, inserted in the internetwork transit exchange of the public network, is assumed to be able to compensate for an echo path delay of 46 ms. The actual echo path delay for the configuration as shown is calculated with $2 \times (10 + 8) = 36$ ms, well below the maximum permitted echo path delay of the echo canceller EC-pu. In this situation, an additional echo canceller EC-pr within the private network is not necessary. + +![Diagram illustrating the use of echo cancellers in an internetwork or international connection. It shows a 'Private network' on the left with an 'EC-pr' (echo canceller) and a 'Public network' on the right with an 'EC-pu' (echo canceller) at the 'Internetwork Transit-exch*'. The 'Public network' is further divided into 'Local exch (N.A.) National (EU)' and 'Long distance or international network'. The diagram indicates mean one-way delays of 10 ms for the private network and 8 ms for the public network. The total echo path delay for the EC in the internetwork transit exchange is calculated as 2 x 18 = 36 ms, which is less than the maximum echo path delay of 46 ms for the EC-pu.](b5b908b453ca50ed3b4cca88aef080fa_img.jpg) + +The diagram shows a network configuration with the following components and delays: + +- Private network:** Contains an 'EC-pr' (echo canceller in private network). The mean one-way delay is 10 ms. +- Public network:** Contains an 'EC-pu' (echo canceller in public network) at the 'Internetwork Transit-exch\*'. The mean one-way delay is 8 ms. +- Local exch (N.A.) National (EU):** Part of the public network. +- Long distance or international network:** Part of the public network. +- Echo path for EC in the internetwork transit exchange:** The total echo path delay is $2 \times 18 = 36$ ms. +- Maximum echo path delay:** 46 ms (for the EC-pu). + +Diagram illustrating the use of echo cancellers in an internetwork or international connection. It shows a 'Private network' on the left with an 'EC-pr' (echo canceller) and a 'Public network' on the right with an 'EC-pu' (echo canceller) at the 'Internetwork Transit-exch\*'. The 'Public network' is further divided into 'Local exch (N.A.) National (EU)' and 'Long distance or international network'. The diagram indicates mean one-way delays of 10 ms for the private network and 8 ms for the public network. The total echo path delay for the EC in the internetwork transit exchange is calculated as 2 x 18 = 36 ms, which is less than the maximum echo path delay of 46 ms for the EC-pu. + +T1211280-99 + +EC-pu Echo canceller in public network + +EC-pr Echo canceller in private network + +\* Transit-exch: local-long distance (N.A.) national-international (EU) + +**Figure 25/G.108 – Use of echo cancellers in an internetwork or international connection** + +The value of 10 ms in Figure 25 for the mean one-way delay within the private network is low, especially for larger networks. When higher private network delay values can be expected, the use of echo canceller EC-pr should be considered, possibly even for some national or longer local carrier connections. This example illustrates, that it is advisable to ask for the relevant information about the properties of the public network, the expected average delay for long-distance and international routing, and the characteristics of the echo cancellers provided by the network. + +## 10.5 Handling of echo cancellers in the E-Model + +The proper application of echo cancellers, such as those in conformance with Recommendations G.168 [12] or G.165 [11], is equivalent to an enhancement of the echo loss. For a specific type of echo canceller, which may be inserted into the network subject to planning, there are two feasible approaches as to how this echo canceller can be considered in the E-Model calculations: + +- If detailed information on the technical data of this echo canceller is available, those values and especially the value for the echo loss enhancement should be used, to calculate actual values for TELR and WEPL. +- If no detailed information on the technical data of this echo canceller (beside its conformance to Recommendation G.165 [11] or Recommendation G.168 [12]) is available, a survey of the expected quality can be achieved by leaving the input parameters for TELR, WEPL, T and Tr at their default values. Thereby the connection is assumed to be "echofree". + +While the first method should be preferred, for detailed transmission planning tasks of actual networks under consideration (i.e. planning a network for a specific customer), the latter method may provide more ease in handling general overview tasks. + +# 11 Realization of planning + +## 11.1 General + +The planning of a private network with respect to speech transmission quality addresses, in general, the investigation of connections that have been identified as critical. In most cases, the critical connection is only one specific connection, but is representative for all comparable terminal equipment: e.g. all telephone sets connected to the same exchange at the same location. + +Planning is necessary in the case of establishing a totally new private network, but also applies in the case of an existing network being modified or amended with respect to major portions or components. In the latter situation, existing portions can also be subject to planning in order to investigate the expected quality between new and existing terminals and other elements, as well as the effect on quality if access and routing to the public network has been changed for the existing terminals. In general, transmission planning should be executed along the following steps: + +- determination of the specific requirements and network features; +- definition of the reference configurations to be investigated; +- determination and collection of all relevant transmission parameters of: + - elements within the private network; + - elements within the public network(s); + - leased lines and tie trunks; +- end-to-end calculation of the expected quality with the E-Model; +- analysis of the results. + +These steps should only be considered as a recommendation. Depending on the actual planning project, they can be modified or amended. Also the proposed sequence should be viewed only as guidance. The following subclauses provide a more detailed description of each of these steps. + +## 11.2 Determination of the specific requirements + +Depending on the business of the user's company, with respect to the specific telecommunication demands, such as different locations to be interconnected, major types of connections, etc., the following characteristics of a private network are usually predetermined and can be varied only to a small degree for the benefit of speech transmission quality: + +- structure and hierarchy of the network; +- routing within the network and to and from the public network(s); +- major types of connections via the public network (international, national long distance, local); +- major types of far-end termination. + +Not directly related to the demands by the user, but nevertheless important for transmission planning the following network aspects should also be taken into account: + +- type and point of access to the public network; +- use of Virtual Private Networks (VPN); +- type, routing and characteristics of national and international tie trunks and leased lines. + +The routing algorithms, as well as routing restrictions within the private network for internal calls and for connections via the public network are of major influence to transmission planning. Detailed knowledge about the routing is necessary to identify critical connections. This should include not only the standard routing but also routing procedures used for network features (e.g. call transfer) or for alternate routing if transmission elements are busy or in failure status. If different transmission + +elements are used for the routing of internal calls, and for calls to and from the public networks, more economical equipment may be used in the routing paths for internal connections. + +In certain private network scenarios, the nature of connections routed to public networks should be determined. As has been stated a number of times in this Recommendation, transmission planning is based on an end-to-end consideration. Consequently, the amount of impairments contributed by the public network portion is important for the planner. As a general rule, the impairments (e.g. delay) contributed by public networks are low for local calls and increasingly higher for national long distance or international connections. If, depending on the business of the user, the predominance of connections via the public network can be assigned to local routing (e.g. within the territory of the local operating company), a higher amount of impairments can then be allocated to the private network for the benefit of more economical solutions. In a competitive environment, several offers of public network access, with different amount of impairments, can be compared on the basis of expected quality and/or possible economical solutions for the private network. It should be noted, that the meaning of "predominance" in this context is a percentage in the range of 90 to 95% (not just more than 50%) for the type of connection considered. + +Furthermore, depending on the customer's business, it may be possible to determine a predominance of a specific type of communication partners, e.g. whether in the residential (subscriber line) or business (another private network) domain. During planning, this will be helpful for the selection of the far-end termination as described in Annex A. If a clear definition of the far-end termination is not possible, the type "single telephone set" should be used. + +Where special access (e.g. direct access to a higher hierarchy public network node), or special low impairment routing for designated calls are provided by some public network carriers, such offerings should be included in the basic determination of the reference configuration. Furthermore, public network operators generally make available tie trunks or leased lines as well as Virtual Private Network (VPN) features for the connection between the switching elements of a private network. Using the E-Model as a tool, an investigation can be made during planning on a quality/cost relation to select between various offerings of access, routing, and connection options. + +## **11.3 Definition of the reference configurations** + +As stated in 11.1, the most critical connections should be identified for transmission planning. This "reference configuration" is based on the structure of the private network, in conjunction with the possible routing alternatives, information about type and point of access to public network(s), predominance of connections, and/or the type of far-end terminations (where applicable). The purpose of the reference configuration is to obtain an overview of all relevant parts of the critical connection considered. It is recommended to diagram this configuration including all relevant terminal, switching, and transmission elements that may contribute impairments. This diagram is also advantageous in the other planning steps for the determination of all parameter values, identification of echo paths and their characteristics, and for the calculation with the E-Model. + +This reference configuration should be defined as an end-to-end configuration including the telephone sets of the private network and of the far-end termination. In most cases, more than one reference configuration should be taken into account, especially if the structure of the private network and the routing is complex and a clear determination of whether a path is critical or not cannot be made without calculation. + +The determination of the reference configurations in large complex private networks is very important to obtaining correct planning results and usually requires a lot of experience and planning practice. When investigating the network, particular attention should be given to elements which introduce additional delay and/or equipment impairments, such as low bit-rate systems and terminals using an airpath (e.g. mobile and cordless terminals). Hybrids (4-wire/2-wire conversions) within the private or public network may form echo paths and should be carefully considered. Although + +connections via public networks to the far-end termination are usually the most critical connections as the basis for the reference configuration, routings fully within the private network may sometimes be found as more critical. + +## **11.4 Determination of the transmission parameters** + +During this step of the planning, all relevant transmission parameters of the different elements in the reference configuration should be determined for: + +- the private network; +- the public network(s); +- tie trunks and leased lines. + +As a minimum the following parameters must be defined for the various elements of the reference configuration: + +- loudness ratings (for telephone sets); +- loss (for switching and transmission elements); +- echo loss (for elements with a 4-wire/2-wire conversion); +- mean one-way delay (along the entire echo path); +- absolute one-way delay (between the two telephones, mainly for international calls); +- number of A/D-D/A conversions (number of qdu in all types of elements, e.g. digital pads); +- equipment impairment factor (in equipment using low bit-rate coding). + +Where appropriate, the location and characteristics of existing echo cancellers in the private or public network should be determined, as well as for which routings they are applied. + +As a rule, these parameter values should be available from the manufacturers or providers of each considered element. For public networks, information on the parameter values based on the type of connection and access may be obtained by negotiations between public and private network operators. This is also true for the characteristics of VPN or for tie trunks and leased lines. For additional information on these parameters and typical planning values, see Annex A. + +## **11.5 End-to-end calculation with the E-Model** + +At this step of the planning process, the defined reference configuration(s), together with all relevant parameter values, are here selected as the calculation basis of the expected quality for the considered configuration. As stated in 9.2, 9.3 and 9.5, this step requires care to assure correct inputs to the E-Model. In most cases it is also necessary to perform pre-calculations for certain input parameters to the E-Model, as described in clause 8. It is strongly recommended to transform the reference configuration into one of the working configurations for the E-Model, as described in 9.2. + +The selection of the appropriate working configuration depends on the reference configuration to be investigated. In case of fully digital connections, it is clear that the working configuration for fully digital connections shown in Figure 21 should be used. The selection process is somewhat more difficult for reference configurations with one or more 4-wire/2-wire conversions (hybrids) within the connection. For example, a configuration with the private network side terminated in a digital telephone set and with an echo path formed by a hybrid, either within the private network or in the public network, a review of the working configurations in 9.2 suggests that the working configuration for 2-wire/4-wire connections, shown in Figure 20, is likely to be most appropriate. + +For the selection of a working configuration, it is critical to make a correct assignment of the send side and the receive side. Basically, the planning principle and the determination of the expected quality is primarily related to the user of the private network. The principle and algorithm of the + +E-Model relates the perceived quality to the receive side of the working configuration. Therefore, the telephone of the private network should be assigned to the receive side of the working configuration for E-Model calculations. + +However, it may also be necessary to investigate the quality for the far-end termination, particularly with respects to any echo effects. For this investigation, the assignment of send and receive side is reversed. Assuming a far-end termination terminated in a hybrid connecting an analogue telephone set (where the talker may be disturbed by echo), the working configuration of Figure 19 should be applied. + +NOTE – When using computer programs, the capability to perform the calculation for both sides without changing the input parameters could be incorporated by the program. Here again it is very important that the planner is completely familiar with all the features and restrictions of the program used for avoiding wrong results. + +For reference configurations with a 4-wire/2-wire conversion within the private network it is recommended to use the working configuration for 2-wire/2-wire connections of Figure 18. When transforming the reference configuration into this working configuration, it is, in some applications, necessary to consider portions of the private network (including, e.g. a PBX and/or a transmission section) as a entity (equivalent to a telephone set). In such applications, the relevant parameters should be combined such that they can be considered as the input parameters for the telephone A in Figure 18. A comparable situation is described in 9.5 in conjunction with a cordless telephone. + +## 11.6 Analysis of the results + +Once the results of planning calculations are available in terms of the E-Model Rating R, a first concern should be for connections where this value is $R \leq 50$ . Lower values of E-Model Rating R are not recommended, even in exceptional cases. The realization or the practical use of a reference configuration which, with its corresponding parameter values, results in lower R values is not recommended. For such connections, either other solutions should be found or other equipment should be selected in order to increase the end-to-end speech transmission quality to higher values. + +It is very important for the planner to fully understand the planning principle recommended in this Recommendation. + +First, that planning is based on an end-to-end consideration in contrast to previous planning practices for private networks where, either through regulation or public network-defined standards, specific limits for the various transmission parameters were specified for the private network section up to the interface to a public network. + +Second, that the result is not in terms of "numbers" for the various parameters to be compared with a specific end-to-end-limit for each parameter, but in terms of a quality perception to be expected by the user when communicating via the investigated configuration. As stated in 4.3, quality is a subjective judgement such that assignments cannot be made to a fixed number for the E-Model Rating R, or to the boundaries between different ranges of the whole quality scale. Rather, the quantitative terms should be viewed as a continuum of perceived quality varying from high quality through medium values to a low quality as illustrated in Figure 26. + +![Figure 26/G.108 – Judgement of a connection on a linear quality scale. The figure shows a horizontal bar representing the E-Model Rating R scale from 100 down to 50. Above the bar, qualitative labels are placed: 'High quality' (approx. 100-85), 'Medium quality' (approx. 85-65), and 'Low quality' (approx. 65-50). The area from 50 down to the right is labeled 'Area not recommended' and is shaded black. Below the bar, a 'Linear quality scale' is indicated with tick marks at 100, 90, 80, 70, 60, and 50. The text 'E-Model Rating R' is on the right, and the code 'T1211290-99' is at the bottom right.](914ed91345d3dbcd749ea65b4b3d6cb2_img.jpg) + +Figure 26/G.108 – Judgement of a connection on a linear quality scale. The figure shows a horizontal bar representing the E-Model Rating R scale from 100 down to 50. Above the bar, qualitative labels are placed: 'High quality' (approx. 100-85), 'Medium quality' (approx. 85-65), and 'Low quality' (approx. 65-50). The area from 50 down to the right is labeled 'Area not recommended' and is shaded black. Below the bar, a 'Linear quality scale' is indicated with tick marks at 100, 90, 80, 70, 60, and 50. The text 'E-Model Rating R' is on the right, and the code 'T1211290-99' is at the bottom right. + +Figure 26/G.108 – Judgement of a connection on a linear quality scale + +Although in Figure 26 a rough distinction is made between high, medium and low quality this should not be interpreted in a way that there is a specific value of R considered as a boundary between high and medium or between medium and low. Only the boundary between low quality and the "not recommended" or unacceptable area is fixed to a value of $R = 50$ . For further guidance in interpreting the results of planning calculations refer to the definition of categories of speech transmission quality as given in Table 1 and to the text of Recommendation G.109 [4]. + +For practical planning, it is recommended that normal connections within the network under consideration, or between the network under consideration and the public or other networks, should result in values for the E-Model Rating of $R \geq 70$ . For exceptional configurations, values for the E-Model Rating of $70 \geq R \geq 50$ are acceptable but lower values should be avoided. It is worthy of note again that, for an end-to-end analysis as performed here, the overall quality is not only influenced by the network under consideration as the subject of planning, but also by public networks. Therefore, it is not practical, in most applications, to perform the planning for a private network with the goal of "high quality" for all possible connections. + +# ANNEX A + +## Transmission parameters for specific elements + +This annex provides additional guidance on the different network elements within the private network, for public networks and for the far-end termination. The nature of these parameters and their relevance to the E-Model is common to both the European and the North American regions as well as to other regions. Where network configurations and parameter values of specific network elements differ between the European and the North American regions, these differences are noted for each specific parameter. + +According to the planning principles of this Recommendation, the investigation of reference configurations is based on an end-to-end consideration and analysis. This requires transmission data not only for the elements within the network under consideration, but also for other networks and for the far-end termination. As a support to the planner, guidance on specific elements within the private networks and other parts of a connection will be given in this annex. Where possible, mainly in case of commonly used elements with standardized transmission data, the parameter values are given directly and can be used for planning. For all other transmission elements or connection elements, instructions will be given as to what data needs to be collected for the purpose of planning and how to analyse and compare this data. + +### A.1 Elements in private and/or IP based networks + +#### A.1.1 Wired telephone sets + +In general, it is assumed, that all telephone sets used in private networks are designed according to standards applicable to the region; e.g. North American industry standards, European standards or national standards. For planning purposes, nominal values should be used, only; tolerances should not be considered. This is also valid if a volume control in receive or send direction is provided. In this case, only the RLR and SLR values for a default setting of this volume control should be used. + +With respect to different impairments and relevant parameters, wired telephone sets can be classified as analogue or digital telephone sets according to their type of interface. + +##### A.1.1.1 Analogue telephone sets + +In Europe the transmission characteristics of analogue telephone sets depend mainly on traditional national loss planning. Therefore, standardized values cannot be provided in this Recommendation and should be available from the manufacturer or network operator. The following parameters are necessary for transmission planning and should be determined: + +| | | +|-------------------------|--------| +| Send Loudness Rating | SLR | +| Receive Loudness Rating | RLR | +| Sidetone Masking Rating | STMR | +| Input impedance | $Z_R$ | +| Balance impedance | $Z_B$ | +| Delay (if applicable) | $\tau$ | +| D-factor of the handset | D | + +In North America transmission characteristics of analogue telephone sets generally conform to industry standards as given in [41]. This standard covers the loudness ratings and impedance values; however, delay (if applicable) and the D-factor are not covered. For sets not designed to this standard, the characteristics should be obtained from the manufacturer. + +In either region, the loudness rating values SLR, RLR and STMR should be defined according to Recommendation P.79 [29]. (To avoid wrong results in conjunction with the E-Model, earlier definitions such as Corrected Reference Equivalent (CRE) values or test methods such as OREM-A or OREM-B, should no longer be used.) The input and balance impedances $Z_R$ and $Z_B$ , if not specified by industry standards, should follow a modern design providing a capacitive complex impedance for optimized impedance matching between telephone set and connected equipment. [Any potential mismatch at this point may influence the STMR of the telephone set, as well as the weighted Terminal Balance Return Loss at a connected hybrid resulting in a low value for TELR (see also A.1.3).] + +The D-factor of the handset should only be considered if a handset design is used which deviates from common geometry. Modern analogue telephone sets may use digital signal processing to provide additional features in some cases. The possible delay caused by this processing should then be determined. + +##### A.1.1.2 Digital telephone sets + +Beside the protocol requirements for digital telephone sets, the transmission characteristics can usually be assumed to be in conformance with Recommendation P.310 [27] or with [49] (Europe) or [42] (North America). However, deviations from these values are possible. The following parameter values may be used directly unless the telephone in use does not meet the referenced standards. + +| | | Europe | North America | +|-----------------------------------|------------------|----------------|------------------------| +| Send Loudness Rating | SLR | +7 dB | +8 dB | +| Receive Loudness Rating | RLR | +3 dB | +2 dB | +| Sidetone Masking Rating | STMR | 15 dB | 18 dB | +| Mean one-way delay | $\tau$ | 1.5 ms | not specified (Note 1) | +| Terminal Coupling Loss (weighted) | TCL w | 40 dB (Note 2) | 40 dB (Note 3) | +| D-factor of the handset | D | 3 | not specified | + +NOTE 1 – For North American digital sets, this value is negligible when compared with other components in the connection scenario. +NOTE 2 – Normalized to SLR = 7 dB, RLR = 3 dB (Europe). +NOTE 3 – Normalized to SLR = 8 dB, RLR = 2 dB (North America); the desirable value is 45 dB. + +North American loudness values for digital sets are being standardized in [42] and [44] and reflect the long-term objectives of Recommendation P.310 [27]. In general, loudness rating values should be in accordance with Recommendation P.79 [29]. For the weighted Terminal Coupling Loss (TCLw), some telephones may provide values higher than those given above. If stated by the manufacturer such higher values may be used for planning purposes. + +##### **A.1.1.3 IP terminals** + +Beside the functions related to the IP applications an IP terminal (H.323 [26] terminal) provides the conversion between the acoustical interface and the IP based network and vice versa. + +It can be observed that practical IP terminal realizations may deviate considerably from the traditional telephone set approach; e.g. headsets/loudspeaker and tie-clamp microphones instead of a handset. Even if it operates similar to a digital telephone set regarding the acoustical interface parameters (see A.1.1.2), the various components of an IP terminal, such as personal computer, soundcard, loudspeaker, microphone and the application software may be provided by different manufacturers, the combination of those components will often be performed by the user. Therefore, the parameters SLR, RLR, TCLw STMR, LSTR and D cannot be automatically set to the default values according Table 6 and are for further study. + +The digital part of an IP terminal may comprise the following components: + +- encoder/decoder; +- Voice Activity Detection (VAD) devices; +- Forward Error Correction (FEC) devices; +- receive buffer; +- packet assembly/de-packetization. + +The actually contained components and their relevant parameters are not standardized as a whole system and thus are for further study. + +#### **A.1.2 Wireless telephone sets (including cordless)** + +Wireless telephones are in common use in private networks to provide the advantage of mobility in conjunction with cellular networks. Due to the coding principles used for the airpath, these telephone sets may contribute additional delay and distortion. + +For the European region it is assumed that wireless telephones comply with the appropriate European or national standards. In Table A.1 an extract is given from the DECT and the GSM standards for all parameters relevant for planning according to this Recommendation. North American wireless sets use either licensed or unlicensed technology, Table A.2 presents the licensed and unlicensed parameters which are relevant for speech transmission quality planning. + +For wireless telephones deviating from these standards, information on the actual values according to the list of parameters in Tables A.1 or A.2 should be available. + +These values apply to the entire configuration consisting of the mobile part and the fixed part, where the fixed part is connected digitally to the adjacent connection or transmission element. + +Due to the high values of mean one-way delay wireless telephones are usually already equipped with integrated control of echo, such as echo cancellers or echo suppressors. Since this provision may also influence decisions on echo cancelling devices in other sections of the network, a careful investigation of their interworking is necessary (see 8.2.2 and A.1.10 for more information, and Annex C specifically related to integrated echo suppression with references to DECT). + +**Table A.1/G.108 – Planning values for wireless telephones – European region** + +| | | DECT | GSM full rate | GSM half rate | GSM enhanced full rate | +|------------------------------------|-----------------------|---------------|----------------------|----------------------|-------------------------------| +| Send Loudness Rating | SLR (dB) | 7 | 7 | 7 | 7 | +| Receive Loudness Rating | RLR (dB) | 3 | 3 | 3 | 3 | +| Sidetone Masking Rating | STMR (dB) | 13 | 13 | 13 | 13 | +| Terminal Coupling Loss weighted | TCL w (dB) | > 46 (Note 1) | > 46 | > 46 | > 46 | +| Mean one-way delay | $\tau$ (ms) | 14 | 95 | 100 | 96 | +| Echo loss of soft suppressor | $a_{ESS}$ (dB) | 9 | – | – | – | +| Artificial echo loss (if required) | $a_{Echo}$ (dB) | 24 (Note 1) | – | – | – | +| Number of qdu (Note 2) | qdu | 0.5 | 0.5 | 0.5 | 0.5 | +| Equipment impairment factor | I e | 7 | 20 | 23 | 5 | + +NOTE 1 – A TCLw of 34 to 46 dB is optional, artificial echo loss required. + +NOTE 2 – qdu only for the A/D-D/A conversion (A-law, Recommendation G.711 [15]), other processes are included in the equipment impairment factor Ie. + +**Table A.2/G.108 – Planning values for wireless telephones – North American region** + +| | | Licensed: TDMA | Unlicensed: PACS
WUPE, PCI, PWT | +|------------------------------------|-----------------------|-----------------------|--------------------------------------------| +| Send Loudness Rating | SLR (dB) | 8 | 8 | +| Receive Loudness Rating | RLR (dB) | 2 | 2 | +| Sidetone Masking Rating | STMR (dB) | 15 | 15 | +| Terminal Coupling Loss weighted | TCL w (dB) | 45 | 45 | +| Mean one-way delay | $\tau$ (ms) | 100 | 7 | +| Echo loss of soft suppressor | $a_{ESS}$ (dB) | – | None | +| Artificial echo loss (if required) | $a_{Echo}$ (dB) | – | None | +| Number of qdu (Note) | qdu | 0.5 | 0.5 | +| Equipment impairment factor | I e | 10 | 7 | + +NOTE – qdu only for the A/D-D/A conversion ( $\mu$ -law, Recommendation G.711 [15]), other processes are included in the equipment impairment factor Ie. + +#### A.1.3 Switching equipment + +It is assumed that switching equipment in a private network, (e.g. PBXs), conform to pertinent regional requirements with respect to their influence on transmission quality. Appropriate requirements can be found in [52] (Europe) or [40] (North America). Note that, in [52], certain significant parameters, notably loss and one-way delay, are no longer specified but are left to manufacturer's declaration. + +Basically switching equipment can be categorized according to the type of internal switching: + +- analogue 2-wire or analogue 4-wire; +- Pulse Amplitude Modulation (PAM); + +- Pulse Code Modulation (PCM) according to Recommendation G.711 [15] (A-law or $\mu$ -law); +- new coding principles, e.g. according to Recommendation G.728. + +Furthermore, for the purpose of transmission planning, different types of interfaces to other connection elements can be considered: + +- interface to connect with public networks; +- interface to connect with other switching equipment of the same private network; +- interface to connect to terminals. + +For the physical layer of these interfaces, a further distinction can be made into: + +- 2-wire analogue; +- 4-wire analogue; +- digital. + +Not all interface/physical layer combinations need to be considered. Table A.3 illustrates the possibilities. + +**Table A.3/G.108 – Switching equipment connection possibilities** + +| Interface to connection elements | 2-wire Analogue | 4-wire Analogue | Digital | +|-----------------------------------------|------------------------------------------------|------------------------------------|------------------------------------------------| +| Public network | Common in North America; phasing out in Europe | Unlikely, except in United Kingdom | Prevalent in Europe; starting in North America | +| Same private network | Mainly between a main PBX and a tributary | Phasing out | Common | +| Terminals | Usual for analogue sets | Not used | All digital terminals, including wireless | + +Switching equipment in a private network usually provides a "through-connection" or "port-to-port connection" between two interfaces, in other words, the switching path is "inserted" into the connection and, therefore, has the potential for contributing transmission impairments. Due to the variety of possible types of through-connections with respect to the physical layer of the interfaces, and considering the various types of internal switching, it is not possible to provide any general norm or guidance about the parameters and their degree of impairment to be considered in transmission planning. However, information should be available from the manufacturer or from general inference with reference to standards on those parameters which may contribute impairments. The most important parameters to be considered for a through-connection are: + +- loss or gain between the two interfaces; +- number of qdu; +- value of equipment impairment factor; +- mean one-way delay; +- echo loss; +- input impedance of 2-wire analogue interfaces; +- balance impedance in 2-wire analogue interfaces (hybrids); +- distortion (including noise, crosstalk). + +The value of loss between two interfaces is a function of the selection of the relative input- and output-level (loss adjustment) values of analogue interfaces, and the insertion of digital loss or gain pads within the switching path. (Reference [40] specifies a port-to-port loss plan between various types of interfaces but does not put requirements on the allocation of loss between interfaces.) + +When new coding laws are used for the internal switching, the value for the equipment impairment factor ( $I_e$ ) should be selected according to Table 2a. With the exception of inserted digital loss or gain pads, the number of qdu can be set to $qdu = 0$ for internal analogue switching (including PAM) with both interfaces analogue, or for internal digital switching (A-law or $\mu$ -law) with both interfaces digital. A value of $qdu = 0.5$ can be used for analogue or digital internal switching, where one of the two interfaces is digital and finally a value of $qdu = 1$ is valid for internal digital switching and both interfaces analogue. In case of digital pads the number of qdu should be increased by 0.7 for each pad in all configurations. + +NOTE – It is assumed that, when loss or gain in an analogue-to-digital path is implemented via codec settings, there is no additional qdu increment beyond the 0.5 value. If the PBX provides A-law/ $\mu$ -law conversion, there may be additional qdu, which must be determined. + +The mean one-way delay is negligible for switching equipment using internal analogue switching and analogue interfaces. For all other types the delay depends upon the types of interfaces and the internal switching. For planning purposes an average value of $T = 1$ ms may be used if PCM, according to A-law or $\mu$ -law, is used for the internal switching, unless otherwise specified by the manufacturer (for guidance see Recommendations Q.551 [36], Q.552 [37], Q.553 [38], Q.554 [39], and References [60], [40] and [44]). + +Whenever a switching equipment path connects a 4-wire interface (analogue or digital) to a 2-wire interface (or a 4-wire switch path connects two 2-wire interfaces), the echo loss of the terminating hybrid in the 2-wire interface(s) should be considered. The input and balance impedances of any 2-wire interface are not directly subject to planning; however, specifications should be available to determine whether adequate impedance matching at these interfaces is provided. (Reference [40] specifies minimum balance requirements for various types of 2-wire interfaces.) + +The echo loss (4-wire return loss in North America) of a 4-wire/2-wire conversion is a very important value for the calculation of the Talker Echo Loudness Rating (TELR), as an input parameter to the E-Model. Together with the mean one-way delay of the echo-path, TELR contributes directly to the important impairment factor of echo performance. The echo loss of a 2-wire termination includes any loss adjustment (relative levels) of the hybrid in the 2-wire interface (in both send and receive directions) and the Terminal Balance Return Loss (TBRL) (Hybrid Balance in North America), of the interface. (In North American scenarios, the hybrid loss adjustment and PBX network loss provision, if any, are usually combined into a single value for port-to-port loss.) This TBRL (hybrid balance) is a function of the degree of matching between the balance impedance of the hybrid and the impedance of the connected terminal, transmission or connection element at the 2-wire side, and should be available as a weighted value (TBRLw or weighted hybrid balance). See Recommendation G.122 [7] for more information about this weighting algorithm. + +Balance networks and input impedances of modern switching equipment provide a capacitive complex characteristic to obtain an improved match to the characteristic of unloaded cable sections. (Recommended balance networks are described in [52] and in [40].) If the 4-wire/2-wire conversion is made via an analogue 4-wire interface, the loss adjustment in this interface card should also be included. The same applies for digital pads irrespective of their location. + +For European scenarios, assuming a standard loss adjustment of 0 dB (0 dBr) in sending direction and of 7 dB (–7 dBr) in receiving direction as for line cards and interfaces to other equipment and a balance network following the capacitive complex approach, the following average values for the TBRLw and the echo loss can be assumed in planning: + +**Table A.4/G.108 – Average values for TBRLw and echo loss (Europe)** + +| Termination at the 2-wire side | TBRLw | Echo loss | +|------------------------------------------------------------------------------|--------------|------------------| +| Analogue telephone set with complex input impedance (negligible line length) | 18 dB | 25 dB | +| Analogue telephone set with non-complex input impedance, e.g. 600 ohms | 7 dB | 14 dB | +| 2-wire-cable section (unloaded) | 10 dB | 17 dB | +| Other equipment with complex input impedance (negligible line length) | 18 dB | 25 dB | + +In some configurations lower values are possible. If interfaces are using adaptive balancing, the relevant information should be available from the manufacturer. + +For North American switching equipment, Reference [40] provides minimum hybrid balance requirements (22 dB in the echo band) for analogue terminal interfaces (called "ONS") when measured against 600 ohms, and for all other 2-wire interfaces measured either against 600 ohms or against a complex capacitive impedance. Average hybrid balance values are not specified. North American systems do not have standard line card loss values; therefore, echo loss values cannot be given; however, the port-to-port loss of the terminating system should be included in the calculation of overall TELR of an end-to-end connection. For planning purposes in North America, assume an average hybrid balance of 12 dB to lines and 10 dB for unloaded cable sections (with no impedance matching). + +#### **A.1.4 IP gateways** + +The specific functions of the gateway will depend on whether the direction of transmission is from the Internet to the PSTN or vice versa. In particular, the functions in the gateway include (but are not limited to): + +- Internet → PSTN + - Packet disassembly (including "IP stack") + - Speech decoder (including error concealment, comfort noise, silence insertion, etc.) + - Management or regulation of delay variation + - Echo cancellation. +- PSTN → Internet + - Speech encoder (including silence removal, comfort noise, etc.) + - Packet assembly (including "IP stack"). + +#### **A.1.5 Leased lines and tie trunks** + +In private networks, leased lines and ties trunks, as provided by public network operators, are used to interconnect switching elements or to connect terminals to switching equipment. In North America, leased facilities between switching equipment are termed tie trunks; leased facilities used for connecting terminals in a location remote from their serving switching equipment to that equipment are called off-premise lines. In Europe, such facilities are called leased lines for either purpose. + +With respect to their interface presentation, leased facilities can be grouped into the following basic categories: + +- 2-wire analogue; +- 4-wire analogue; +- digital. + +For the purpose of transmission planning, digital leased facilities are independent of their physical layer (64 kbit/s, basic rate access or primary rate access); for transmission planning, only the 64 kbit/s-channel layer is addressed. Leased facilities with analogue interfaces at both ends may also include digital sections and a closed 4-wire loop. Furthermore, in some cases analogue facilities may be available with 2-wire interface at one end and a 4-wire interface at the other end or a facility may have an analogue interface at one end and a digital interface at the other end. + +Leased facilities differ not only in their type of interfaces but also in their length. Therefore, standard planning values cannot be stated here. Transmission data should be made available by the provider. The following list may be considered as a guide for the planner when asking for parameter values: + +- End-to-end Loss (in both directions) for facilities with analogue interfaces, 2-wire and 4-wire. +- Relative input and output levels for facilities with analogue interfaces. +- Number of qdu for all types with the exception of facilities with fully digital routing and digital interfaces on both ends. +- Equipment impairment factor for lines using DCME, ADPCM, or other new coding laws. +- Mean one-way delay for all types. + +North American analogue facilities for tie trunks generally are designed to Via Net Loss (VNL) rules (loss proportional to facility length) except for short-haul tie trunks which operate with a fixed loss. Facilities used for off-premises terminals usually employ twisted pairs (loaded or non-loaded), with Voice Frequency Repeaters (VFR) inserted, where necessary. Approximate analogue facility loss values are: + +- VNL trunks: $0.4 \text{ dB} + 0.0015 \times \text{length in miles}$ ; maximum 2.9 dB. +- Short-haul trunks with fixed loss: 2 dB. +- Off-premises lines for terminals: 0-4.5 dB. + +It is very important that the information about these parameters as given by the providers is based on "actual" values for the specific leased facility, instead of maximum values as derived from a "worst-case" consideration. This enables the planner to avoid an unnecessary insertion of echo cancellers and, in some cases, to allocate a higher amount of impairment values to other private network elements. + +#### A.1.6 Privately owned cable links + +Beside leased facilities, privately owned cable links may be used in some private networks; mainly connecting terminals, key systems, and small PBXs to larger switching elements. Only 2-wire unloaded cable sections are considered here, contributing with loss in sections A1 or B1 of the working configurations as defined in Figures 18 through 20. For planning purposes, the loss of such a cable section can be expressed as Circuit Loudness Rating (CLR) in dB, a value which can be added directly to the SLR and RLR of the telephone sets in the pre-calculation for $\text{SLR}_S$ and $\text{RLR}_R$ (see 8.1). + +The CLR can be calculated with the following formula: + +$$CLR = 0.015\sqrt{RC} \text{ in dB/km}$$ + +where: + +R = Cable loop resistance in Ohm per km + +C = Cable capacitance in nF per km. + +#### A.1.7 Satellite links + +When satellite links are used as part of the private network, all relevant parameters, as were listed for leased facilities, should be available. The most important parameter for possible impairments is the mean one-way delay. It should be taken into account, that the total delay consists of the main delay between the two earth stations as well as a possible additional delay between the earth stations and the interface of switching equipment within the private network to which the link is connected at either or both ends. These values should be made available by the satellite operator. For the satellite links via quasi-stationary satellites in a 36 000 km orbit, a value of $T = 260$ ms between the earth stations can be used for planning purposes. The equivalent values for satellites in lower orbits should be provided by the operator. + +#### A.1.8 Low bit-rate coding + +For private networks, the use of low bit-rate coding can result in more economical solutions. In many cases, digital (leased) facilities used for connection elements are equipped with systems especially designed to provide a flexible "bandwidth on demand" feature, utilizing the given number of 64 kbit/s-channels of the connection in a more economical way, mainly for data transmission. For speech channels, low bit-rate coding, in conjunction with methods called Voice Activity Detection (VAD), will reduce costs in a similar way. + +For transmission planning, it is absolutely necessary to identify all possible impairments which may be introduced by such systems. Beside others, the main parameters to be considered are distortions and delay. These factors depend on the type of low bit-rate encoding. In general, systems can be classified between the following principles: + +- Waveform coder + +Independent of the bit-rate used, all so-called waveform coders reproduce, more or less, the original waveform at the output after decoding. These coders employ mainly the different ADPCM algorithms described in Recommendations G.721, G.726, and G.727. + +- Non-waveform coder + +The basic difference in the coding process is an analysis of the speech signal at the coder input, resulting in a transmitted digital signal with reduced bit-rate which has no relation anymore to the original waveform. The decoder then performs a speech synthesis again. This category includes the RPE-LTP-coder (used in the GSM-standard) and the LD-CELP coder according to Recommendation G.728. Furthermore, there might be a variety of non-standardized coding principles, also called "proprietary coder". + +- "Squelch"- oriented principles + +Reduction of the transmitted bit-rate is performed by detecting speech pauses (VAD). + +The influence of those equipment and coding principles to speech quality can only be defined as a result of subjective tests, expressed in a value for the equipment impairment factor ( $I_e$ ). For standardized low bit-rate coders, values are given in Table 2a. In all other cases the equivalent values and all further necessary information should be provided by the manufacturer. This applies mainly for the mean one-way delay of such a system. It should be noted that some coding principles may provide different options, with important influence to the system specific delay and that some systems are using a variable bit-rate to adapt to different traffic situations. If low bit-rate systems are used in conjunction with a digital leased line, the system-specific delay is increased by the delay of the leased line. + +Some of those systems may also insert a loss to prevent other parts, e.g. integrated echo cancellers, from too high speech levels. Due to the system-specific delay some systems can already be equipped with integrated echo cancellers. The transmission data of those devices should be considered carefully during planning, mainly in conjunction with echo cancelling in other sections of the investigated connection. For further information see A.1.10. + +#### **A.1.9 Packetized voice** + +For the benefit of economical utilization of standard or higher order digital (leased) lines a packetized transmission will be used also in private networks, such as Asynchronous Transfer Mode (ATM) or Frame Relay. The nodes of such systems may also be located in different networks. It is necessary to clearly identify these nodes during planning and to investigate, whether more than one packetized section is included in a connection. + +The packetization of the speech signal causes additional delay, depending on the cell orientation and transfer mode. Therefore, information should be available for planning purposes about this delay, expressed as a value for the mean one-way delay in ms. + +#### **A.1.10 Echo cancellers** + +As already described in 7.2 and 8.2, the result of a planning calculation may show that the E-Model Rating R is mainly influenced by the impairment value for echo and delay ( $I_d$ ). In these situations, the decision should be made to insert echo cancelling devices. In modern networks, only echo cancellers are used because they have various advantages in comparison to the formerly used echo suppressors. Therefore, this subclause only deals with the requirements and technical data of echo cancellers. + +For the application of echo cancellers, several aspects should be taken into account. At first, an investigation should be performed about the correct and optimized location where cancellation should be inserted in the network. This decision can be influenced by echo control devices which are already available either within the private network, e.g. in some specific terminal elements or connection elements, or in other (public) networks. More information and rules for the insertion of echo cancellers are given in clause 10. + +A second aspect which should be taken into account are the technical characteristics of echo cancellers which may vary by a high degree due to their design and application. For all echo cancellers which are not integrated in specific equipment, only devices should be used following, in all parameters Recommendations G.168 [12] or G.165 [11]. Echo cancellers integrated in specific equipment are usually designed for this specific application and, therefore, not necessarily following G.165 [11] in all data. + +NOTE – The characteristics of echo cancellers according to Recommendation G.165 [11] are measured using a noise signal. If results gained with other test signals are also available, e.g. with artificial voice according to Recommendation P.50 [28] or with composite source signals, these data will provide a more accurate issue on the effectiveness. + +The analysis of the technical data of an echo canceller should be made in conjunction with the designated location, mainly with the characteristics of the echo path, the part of a connection between the echo canceller and the source for signal reflections to be compensated. The routing of the echo path should be bit-transparent and the actual values for the mean one-way delay and echo loss should be determined. For local or long distance calls, where no echo control is usually applied in public networks, the use of echo cancellers can become necessary due to additional delay within the private network. In this situation, the responsibility for sufficient echo control is by the private network operator. However, in most cases both talkers will encounter echo effects, i.e. a pair of echo cancellers should be inserted within the private network if no specific arrangements with the public network operator exist. + +![Diagram illustrating echo cancellers (EC A and EC B) in a private network and their echo paths. The diagram shows a 'Private network' on the left and a 'Public network' on the right, separated by a dashed line. In the private network, there is a hybrid connected to a switching equipment, which is connected to 'Low bit-rate equipment' containing 'EC A'. An echo path (labeled 'Echo path A') is shown within the private network, with a mean one-way delay 'A'. 'EC B' is also located in the 'Low bit-rate equipment'. An echo path (labeled 'Echo path B') is shown extending into the public network, with a mean one-way delay 'B (in public network)'. Arrows indicate the 'Direction of echo path'.](5e05915b2a93a3b404422e0966a7c924_img.jpg) + +The diagram illustrates the network architecture and echo paths. On the left, a 'Private network' contains a hybrid connected to switching equipment, which is then connected to 'Low bit-rate equipment'. This equipment contains two echo cancellers, 'EC A' and 'EC B'. 'EC A' has an associated 'Echo path A' within the private network, characterized by a 'Mean one-way delay A'. 'EC B' has an associated 'Echo path B' that extends into the 'Public network' (on the right), characterized by a 'Mean one-way delay B (in public network)'. A dashed vertical line separates the private and public networks. Arrows indicate the 'Direction of echo path' for both paths. The label 'T1211300-99' is present in the bottom right corner of the diagram area. + +Diagram illustrating echo cancellers (EC A and EC B) in a private network and their echo paths. The diagram shows a 'Private network' on the left and a 'Public network' on the right, separated by a dashed line. In the private network, there is a hybrid connected to a switching equipment, which is connected to 'Low bit-rate equipment' containing 'EC A'. An echo path (labeled 'Echo path A') is shown within the private network, with a mean one-way delay 'A'. 'EC B' is also located in the 'Low bit-rate equipment'. An echo path (labeled 'Echo path B') is shown extending into the public network, with a mean one-way delay 'B (in public network)'. Arrows indicate the 'Direction of echo path'. + +**Figure A.1/G.108 – Echo cancellers in a private network and their echo paths** + +This configuration, with two echo cancellers EC A and EC B in a private network and the definition of both echo paths, is illustrated in Figure A.1. The device EC A with its echo path within the private network is suppressing the echo for the public network talker and vice versa. + +For echo cancellers' in accordance with Recommendation G.165 [11], the echo path should provide a minimum echo loss of 6 dB for sufficient operation. This value should mainly be controlled when the echo path is terminated by a hybrid which is also used for a loss compensation (gain) of the connected 2-wire section. For some echo cancellers this required minimum value can be lower or adjustable. + +The most important characteristics are the mean one-way delay of the echo path and the range of delay, also called the "tail delay", the echo canceller is able to compensate. To avoid confusion, it should be noted that tail delay of the echo path is usually expressed as mean one-way delay in transmission planning, while the corresponding data of an echo canceller are given as total tail delay in ms. Consequently, for the decision whether a specific echo canceller is suitable for the given configuration, the data of the device should be compared with twice the value of the mean one-way echo path delay. To guarantee sufficient operation, the echo canceller value should be 6-8 ms higher than the value of the echo path. For echo cancellers according to Recommendations G.168 [12] or G.165 [11], the ability to compensate can be assumed in the range of 40 to 60 ms. Contrary echo cancellers integrated in specific devices may provide lower values. If, for instance, the EC A and EC B in Figure A.1 are integrated in a low bit-rate equipment and are designed only for point-to-point connections (echo path only through a switching equipment) with low values to be compensated, the echo path delay B via the public network can be much higher than the corresponding value of EC B. + +A further aspect which should be considered is the "linearity" of the echo path, which means in this case a routing consisting of only bit-transparent elements in conjunction with a standard decoding/coding at the terminating hybrid. Most echo cancellers use an adaptation and cancelling algorithm based on such a configuration. Where the echo path consists of equipment using low bit-rate coding, the correct operation of the echo canceller cannot be guaranteed. + +The ability of an echo canceller to suppress echo signals is expressed as residual echo level. This is usually not a constant value; but, depends on the speech level at the input and the actual echo loss of the echo path. The value can either be given as residual echo level in dB or also as Echo Return Loss Enhancement (ERLE). Since a total compensation cannot be obtained, the residual echo level is additionally suppressed by a Non-Linear Processor (NLP), also called centre clipper. This suppression is referred to a threshold level, i.e. all residual echo below this threshold will be suppressed. This threshold level is usually expressed in dBm0-values and should be in the range of -35 to -38 dBm0. If the values are in accordance with Recommendations G.168 [12], G.165 [11] or + +with specific requirements (e.g. DECT standard), impairments due to echo can be neglected for the investigated connection, which means the input value for TELR to the E-Model can remain on its default value of 65 dB. + +The principle of an echo canceller and its algorithm is based on an adaptation process which may take a specific time until a sufficient replica of the echo signal is obtained. This time is called the convergence time and should be as short as possible to avoid disturbing effects at the beginning of a voice sequence. Sufficient quality is given for times with less than one second. + +Depending on the algorithm used, extremely high speech levels at the input of the echo canceller may cause distortions and reduce the performance of the adaptation process. The control of this level should be included in the transmission planning. In general, the speech level is sufficiently low if the sending loudness rating at the echo canceller input is $SLR \geq 7$ dB. + +When echo cancellers are inserted in a connection, the bit-transparency is violated. This is important for specific types of data transmission requiring transparent routing and should be taken into account accordingly. Although non-voice services via the private network such as fax and other modem applications, do not require a bit-transparent transmission path, the data handling can be disturbed in some cases. Most modems transmit a signal tone, the so called "disabling tone" with a frequency of 2100 Hz, before starting the transmission, to disable inserted echo cancellers. Depending on the given applications in the private network, the echo cancellers should provide this feature. + +### A.2 Transmission parameters of public networks + +Along with the basic planning principles of this Recommendation, that end-to-end planning is finally executed when the actual values for all relevant transmission parameters in every section of a connection are known, the data of public networks will have a major influence to the resulting quality. If these values are available as real values with an acceptable accuracy, in most cases the unused part of the different parameters within the public network can be used by the private network to provide an economical design. This results in greater flexibility for private network planning in contrast to previous rigid regulations with a fixed apportionment between the networks. + +When, during the planning process, these values have to be defined, correct values can only be obtained on the basis of cooperation or negotiations between the private and public network operators. Taking into account that this planning method is mainly applicable for large private networks with a high number of interconnecting channels, a sufficient exchange of information may be assumed. + +For the investigation of the actual transmission characteristics of a public network, the main types of connections and the type of access (interconnection) should be considered. In this sense, the public network can be considered as a "transit network", providing circuit switched connections between the access point and any other far-end termination (single telephone, PBX or other private networks), or with interfaces to other public networks. Several possible scenarios for access, and routing to and between different public networks, are shown in Figure A.2. It should be noted that the connections in this figure are only examples; i.e. a variety of other configurations, depending on competition and liberalization, are possible. + +NOTE – Scenarios involving IP networks are not considered in the following. + +Considering first European scenarios, the several types of interconnection with public networks can be described as follows: The main national public network accessed via point A provides connections to far-end terminations either in the local area as via point D, or as a long distance call to point A. The same network usually also provides connections to international networks via point B, entering another national network in a foreign country via point O for a connection to a far-end termination via P. + +![Diagram illustrating access and routing in public networks. A private network on the left connects via a central switch to four public network paths. Path 1 (top) goes through points L, M, N to a 'Public network international' containing switches O and P, ending at a 'Far end termination'. Path 2 goes through points D, A, B to a 'Public network national' containing switches C and F, ending at a 'Far end termination'. Path 3 goes through points G, H, E, A, B to the same 'Public network national' and termination. Path 4 (bottom) goes through points I, J, K to another 'Public network national' containing a switch, ending at a 'Far end termination'. A 'Local area' is indicated between points D and A. A dashed line connects point F to point J. The diagram is labeled T1211310-99.](5cc4a2ef554f31ea0577731931007fff_img.jpg) + +Diagram illustrating access and routing in public networks. A private network on the left connects via a central switch to four public network paths. Path 1 (top) goes through points L, M, N to a 'Public network international' containing switches O and P, ending at a 'Far end termination'. Path 2 goes through points D, A, B to a 'Public network national' containing switches C and F, ending at a 'Far end termination'. Path 3 goes through points G, H, E, A, B to the same 'Public network national' and termination. Path 4 (bottom) goes through points I, J, K to another 'Public network national' containing a switch, ending at a 'Far end termination'. A 'Local area' is indicated between points D and A. A dashed line connects point F to point J. The diagram is labeled T1211310-99. + +**Figure A.2/G.108 – Access and routing in public networks** + +Beside the main national network, other public networks might be available, via access point I, with their own far-end terminations (terminals) via point K or with interconnections to the main public network via J and F. Furthermore, public networks operating only in the local area may exist, as shown in Figure A.2, via access points G and H, where H is again connecting to the main public network via E. Finally, international operating network providers can offer direct international access with the access point L, connecting the private network in a direct path with the national public network in a foreign country via the interconnections M and N. + +For North American interconnection scenarios, Figure A.2 can be described as follows: Access point A is connected to the local serving office of the Local Exchange Carrier (LEC), which provides connections to another local termination (point D), to intra-LATA far terminations (point A in the same LATA), or via Interexchange Carriers (IC) to far-end terminations (point C in a different LATA) or to international carriers (via points B and O). Access could also be directly to an IC (access point I), again to terminations also with direct access to that IC (point K) or to another IC or LEC (via points J and F). Access point G illustrates connections to an alternate local service provider (either a re-seller or an IC) or connection via a wireless service. Private networks may also have direct access to international carriers (point L). + +These examples, for possible interconnections of a private network with public networks, as shown in Figure A.2 for the interface points A, G, I and L, are all subject to transmission planning. The results of investigations about the expected quality for the different interconnections may, for example, be used to compare different offers for interconnection service on a cost/quality basis. Furthermore, any single private network may use more than one of these access types in parallel: e.g. national connections via A or I and international connections via access L. + +For all interconnection points, A, G, I and L, between the private network and the public networks, only digital interfaces are assumed in Europe; for North American scenarios, digital, as well as analogue, interfaces must be considered. Terminations via C, D, K and P in the different networks may be either analogue or digital, depending on the network and the selected far-end termination for planning purposes (see A.3). Interconnections to international lines as via point B may be assumed to be digital or 4-wire analogue. + +In large public networks, diverse routing and call handling for the same end-to-end connection is possible, resulting in a wide range for the transmission parameters (e.g. delay) rather than a single specific value for every call on that connection. It is, therefore, recommended, consistent with basic planning principles, to determine the values more on a statistical basis than on a "worst case" consideration. However, if possible, mean parameter values should be determined for the different categories of calls; i.e. such as local calls (between A and D), national long distance calls (between A and C) or international access (between A and B). + +The determination of values for the different categories of calls should include all parameters which are necessary for the planning of the private network. The following list will give guidance to the planner. It is important to note that only the values between the access points (public network acting as a transit) are part of this determination, explicitly excluding the far-end terminations. + +#### **A.2.1 Loss** + +Loss values should be determined for both transmission directions, particularly if, within the public network, a mixed analogue/digital routing in conjunction with a 4-wire/2-wire conversion may exist. Also the insertion of digital pads and their loss values should be included. + +#### **A.2.2 Mean one-way delay** + +For all parts of a routing within the public network consisting of digital or 4-wire analogue sections, an average value for the mean one-way delay should be determined. In case of different values for the two transmission directions, the arithmetic mean should be used for planning. If the call routing also consists of 2-wire sections within the public network(s), any possible delay of such sections should not be included with respect to echo calculations. Specific attention should be given to the possible additional delay resulting from the use of ATM as well as for routing via radio (e.g. for points G and H in Figure A.2) or via satellite links (e.g. for points L and M in Figure A.2). + +#### **A.2.3 Echo loss** + +Values for an average echo loss should mainly be determined if the routing within the public network contains a 4-wire/2-wire conversion (hybrid). For such a terminating hybrid, the average echo loss should be available as weighted echo loss. For more information about the algorithm to obtain a weighted value see Recommendation G.122 [7]. If additional loss within the 4-wire part of the routing is inserted, e.g. in analogue 4-wire systems (FDM) or as digital loss or gain pads, the sum of these values of both transmission directions should be included in the information of the network operator, since they are not only part of the echo loss for the given 4-wire/2-wire configuration but also part of the final calculation of TELR. + +#### **A.2.4 Insertion of echo cancellers** + +Information should be given from the network operator on the insertion of echo cancellers, their location and technical data, and for which category of calls (e.g. international calls only) and routing they are inserted. This information is very important for the planner of the private network when determining whether or not echo cancellers need to be provided within the private network. In Europe echo cancellers are mainly applied on international calls; however, in some cases, mainly between adjoining European countries, echo cancellers are not required. In North America echo cancellers are used on domestic connections where the mean one-way delay is likely to exceed 12.5 ms. In either region echo cancellers may be provided if ATM or low bit-rate coding systems are in use. + +From the point of view of the technical data (see also A.1.10) it may be assumed that devices as used in public networks are, in most cases, compliant with Recommendations G.165 [11] or G.168 [12]. For mean one-way delays of more than 5 ms within the private network, the maximum tail delay for which the echo canceller is able to compensate, should be stated by the provider. + +#### **A.2.5 Quantization distortion units (qdu)** + +The number of qdu is decreasing with the increasing digitalization of public networks. For planning purposes this value is important mainly if the private network routing or elements result in added qdu contributions. As already stated in 8.4, only A/D-D/A conversions, according to Recommendation G.711 [15] (A-law or $\mu$ -law), and digital loss or gain pads should be included in the planning by assigning a value of qdu to them. For other coding principles such as ADPCM or low bit-rate coders the factor $I_e$ should be used. + +#### **A.2.6 Equipment impairment values ( $I_e$ )** + +Information from public network operator(s) should include values for the equipment impairment value ( $I_e$ ) if low bit-rate coding systems are used in any portion of the connection. This is also important in case of radio sections; e.g. when using ADPCM according to the DECT standard [50]. When standardized coding laws are used, the values as listed in Table 2a can be used for planning. + +#### **A.2.7 IP transmission related parameters** + +Transmission in IP networks is accomplished by assembling multiple bytes into packets. These packets include headers with essential information such as source and destination for the packet, which is added at the transport and network layers. The size of the payload and of the header may vary, depending on the application and on the nature of the protocols being used. Communication between two end-points is via a "data stream" (somewhat analogous to a connection in a connection-oriented network such as the PSTN), which usually consists of multiple packets. Each of the packets from a given source may take different routes to a given destination. As a consequence, packets from a given data stream may arrive at the destination in an order that is different from the order in which they were transmitted (i.e. the packets arrive out of sequence). Protocol features such as sequence numbers or time stamps allow the packets to be reassembled in the proper order at the destination. + +Proper sequencing of the packets in the data stream is the responsibility of the higher layers in the protocol stack and is not part of the IP protocol. When an application requires the arriving packets to be used in proper sequence, sufficient delay must be included to allow integration of late packets. For applications such as speech communications, where end-to-end delays as short as possible must be maintained, it may be necessary to declare "very late" packets as lost in order to achieve acceptable delay. The trade-off between long delay (which may result in higher speech transmission quality, but will increase the difficulty of conversation) and dropped packets (which will result in lower speech transmission quality, but will ease the ability to have an interactive conversation) must be given careful consideration when designing VoIP services. + +A conclusion from the afore-said may be drawn by the reader of this Recommendation that the optimization processes in this field have not yet been finalized and that hitherto no standardized solutions are available. Hence, detailed explanation on the mechanisms and impacts of an IP transmission should be requested from the provider. + +### **A.3 Transmission parameter of the far-end termination** + +The planning principles recommended in this Recommendation are based on end-to-end performance considerations. Thus, the results of the transmission planning should produce a reasonable estimate of the speech quality to be achieved. These principles require the inclusion of various far-end terminations. It is not possible to obtain all the relevant information regarding the complete public network connections, especially the details of the far-end terminations. Therefore, it will be necessary to use assumptions based on average values to complete the planning. + +To determine the transmission characteristics of the far-end termination, it is necessary to consider two possibilities. The first is calls terminating at a single telephone (residential) and the second is calls terminating on a PBX or private network (business). If the private network planner can identify + +which category is predominant, this information can be used to perform a more realistic planning (predominance is considered achieved when 95% or more of the calls are in one category). + +#### A.3.1 European far-end termination scenarios + +For the definition of a far-end termination including all relevant transmission parameters, three different types of termination are recommended as shown in Figure A.3a. It should be stated, that configuration and values of these three terminations should be considered as nominal, only. National loss planning and national regulations may also result in other more realistic configurations and/or values. Where average values and additional information for a specific country or a specific far-end termination are available and deviate from those shown in Figure A.3a, such values and configurations should be preferred. + +The single telephone is assumed to be connected 2-wire analogue to the public network with an average loss of the subscriber line of 4 dB. This subscriber line is considered as part of the whole termination. The configuration may also include a small PBX with analogue switching and negligible loss. The telephone set is assumed to have nominal loudness values of SLR = 4 dB and RLR = -7 dB resulting in SLR = 8 dB and RLR = 3 dB for the entire far-end termination. The LR values may deviate for standard telephone sets in a country from the values given above. The mean one-way delay and value of qdu are both assumed to be 0 in this termination. + +![Figure A.3a/G.108 – Configurations and transmission characteristics for the far-end termination – Europe. The diagram shows three scenarios: 1. Single telephone set: Shows a subscriber line (4 dB loss) connected to a telephone set. Transmission characteristics: RLR = -3 dB, SLR = 8 dB. 2. PBX: Shows a subscriber line (4 dB loss) connected to a PBX. Transmission characteristics: RLR = 3 dB, SLR = 7 dB, Mean one-way delay 3 ms, Echo-loss 24 dB. 3. Private network: Shows a subscriber line (4 dB loss) connected to a Low bit-rate system (32 kbit/s ADPCM, I_e = 7), which is then connected to a Private network. Transmission characteristics: RLR = 3 dB, SLR = 7 dB, Mean one-way delay 25 ms, Echo-loss > 46 dB.](28f2f470a7b2446ae5f525123534383c_img.jpg) + +The diagram illustrates three far-end termination configurations for Europe, labeled from top to bottom: + +- Single telephone set:** A subscriber line with a 4 dB loss connects to a single telephone set. The Return Loss Ratio (RLR) is -3 dB, and the Speech Loudness Ratio (SLR) is 8 dB. The telephone set itself has an RLR of -7 dB and an SLR of 4 dB. +- PBX:** A subscriber line with a 4 dB loss connects to a PBX. The RLR is 3 dB, and the SLR is 7 dB. The mean one-way delay is 3 ms. The echo-loss is 24 dB. +- Private network:** A subscriber line with a 4 dB loss connects to a Low bit-rate system (32 kbit/s ADPCM, $I_e = 7$ ), which then connects to a Private network. The RLR is 3 dB, and the SLR is 7 dB. The mean one-way delay is 25 ms. The echo-loss is > 46 dB. Echo cancellers (EC) are shown at both ends of the low bit-rate system. + +T1211320-99 + +Figure A.3a/G.108 – Configurations and transmission characteristics for the far-end termination – Europe. The diagram shows three scenarios: 1. Single telephone set: Shows a subscriber line (4 dB loss) connected to a telephone set. Transmission characteristics: RLR = -3 dB, SLR = 8 dB. 2. PBX: Shows a subscriber line (4 dB loss) connected to a PBX. Transmission characteristics: RLR = 3 dB, SLR = 7 dB, Mean one-way delay 3 ms, Echo-loss 24 dB. 3. Private network: Shows a subscriber line (4 dB loss) connected to a Low bit-rate system (32 kbit/s ADPCM, $I_e = 7$ ), which is then connected to a Private network. Transmission characteristics: RLR = 3 dB, SLR = 7 dB, Mean one-way delay 25 ms, Echo-loss > 46 dB. + +Figure A.3a/G.108 – Configurations and transmission characteristics for the far-end termination – Europe + +The second termination illustrates a "standard PBX" or a small network as typical for terminations in the business environment. The interconnection with the public network and between the two PBXs is assumed to be digital, however, the telephone is connected on an analogue port via an extension line with negligible length. The required 4-wire/2-wire conversion within the PBX forms an echo path with a weighted echo loss of 24 dB. The mean one-way delay of the echo path is chosen as 3 ms. The loudness rating values are referred to the digital interface with SLR = 7 dB and RLR = 3 dB, following [54] for digital interfaces to public networks. The value of qdu is assumed to be 0.5, (one-half of an A/D-D/A conversion), with no digital loss pads being used. + +The third configuration simulates a "typical" routing within a large private network. Again, the interface to the public network and the interconnections between the PBXs are assumed to be digital. Between the first and second PBX a low bit-rate system is inserted into the call path, using ADPCM with $l_e = 7$ in conjunction with Voice Activity Detection (VAD), thus contributing additional delay. The mean one-way delay between the public network interface and the terminating hybrid (with a 2-wire analogue extension line) is set to 25 ms, including the delay due to VAD. Because of this high value of delay, echo cancellers are enabled for both directions (echo paths). The echo loss as provided by this termination can, therefore, be assumed to be very high, and the value of TELR should be set to default according to Table 6. The loudness ratings are the same as for the second configuration SLR = 7 dB and RLR = 3 dB (in accordance with [54]); likewise, the value of qdu for this far-end termination can be assumed to be 0.5. + +#### **A.3.2 North American far-end termination scenarios** + +North American far-end terminations can best be classified by the type of access line. Reference [44] defines two types of access lines, analogue and digital. These are illustrated in Figure A.3b for connections to subscriber lines and connections to a PBX. Loudness values are those specified in [44] as characterizing access lines to the North American PSTN. For specific connections, other values may apply. + +![Figure A.3b/G.108 – Configurations and transmission characteristics for the far-end Termination – North America. The diagram shows four transmission paths: 1. ANALOGUE ACCESS LINE to an Analogue telephone set: RLR = -3 dB, 3 dB loss in the line, SLR = 11 dB. 2. ANALOGUE ACCESS LINE to a PBX: RLR = -3 dB, 3 dB loss in the line, SLR = 11 dB. 3. DIGITAL ACCESS LINE to a Digital telephone set: RLR = 2 dB, Echo-loss 45 dB, SLR = 8 dB. 4. DIGITAL ACCESS LINE to a PBX: RLR = 2 dB, Echo-loss 21 dB, Mean one-way delay 2.5 ms, SLR = 8 dB. Each path is shown with a line, a termination device (telephone set or PBX), and associated transmission parameters.](811d62d08ce934a2a7e5bd877abff7ad_img.jpg) + +Figure A.3b/G.108 – Configurations and transmission characteristics for the far-end Termination – North America. The diagram shows four transmission paths: 1. ANALOGUE ACCESS LINE to an Analogue telephone set: RLR = -3 dB, 3 dB loss in the line, SLR = 11 dB. 2. ANALOGUE ACCESS LINE to a PBX: RLR = -3 dB, 3 dB loss in the line, SLR = 11 dB. 3. DIGITAL ACCESS LINE to a Digital telephone set: RLR = 2 dB, Echo-loss 45 dB, SLR = 8 dB. 4. DIGITAL ACCESS LINE to a PBX: RLR = 2 dB, Echo-loss 21 dB, Mean one-way delay 2.5 ms, SLR = 8 dB. Each path is shown with a line, a termination device (telephone set or PBX), and associated transmission parameters. + +**Figure A.3b/G.108 – Configurations and transmission characteristics for the far-end Termination – North America** + +The analogue telephone is assumed to be connected 2-wire analogue to the public network with an average loss of the subscriber line of 3 dB. The subscriber line is considered as part of the whole termination. The telephone set is assumed to conform to the requirements of [41], resulting in $SLR = 11$ dB and $RLR = -3$ dB for the entire far-end termination. The mean one-way delay and number of qdu are both assumed to be zero in this termination. + +The North American PBX loss plan, as specified in [40] is designed so that an analogue telephone on a local loop behind the PBX, connected to the PSTN via an analogue access line with approximately 3 dB loss, appears with loudness values at the PSTN interface equivalent to that of an average analogue access line terminated by an analogue telephone. Thus, if the far-end termination is an analogue access line, there is no difference whether that line terminates to a telephone or to a PBX. + +A digital access line was, initially, defined in [44] as terminating a digital (ISDN-like) telephone with nominal loudness characteristics conforming to ISDN standards. (The 1992 issue of [44] defines these characteristics in historic North American ISDN terms; an update, scheduled for 1998, will use long-range ITU-T terms and values for compatibility with the re-issue of [42].) As shown in Figure A.3b, a digital access line terminated in a digital telephone will provide a far-end termination with the loudness and echo loss characteristics conforming to [42]. + +Recently, the digital access line definition has been expanded to include terminations from any equipment which conforms to the nominal ISDN loudness levels. The PBX loss plan in [40] is designed so that a connection from an analogue telephone to a digital access line will produce loudness levels on the digital access line equivalent to those from a digital telephone. The main difference, for loss planning, is that the combination of loss insertion and the 4-wire/2-wire conversion within the PBX results in an echo path with an average echo loss of 21 dB. [44] guidelines for the application of echo control in networks connecting to the public network suggest a limit of 2.5 ms mean one-way echo delay which can be assumed for the typical connection. The value of qdu is assumed to be 0.5 (one-half of an A/D-D/A conversion), provided that the required loss insertion in the PBX does not use digital pads; otherwise, additional qdu increments must be included in the calculation. + +# ANNEX B + +## Planning examples + +The planning examples contained in this annex are taken from the field of private network planning amended by considerations with respect to IP based scenarios, whereas the method demonstrated in such examples, in general, is applicable to any network Configuration. + +Due to a variety of differences between the European and the North American regions, with respect to network configurations and values for the different network elements, the following planning examples are separated to provide a more realistic scenario analysis with respect to each of these areas. Therefore, clause B.1 deals with examples more related to the European situation, while clause B.2 is presented in a similar manner as clause B.1, but with specific North American details. + +NOTE 1 – Planning examples for other regions have not been provided because the two different approaches to transmission planning given in this annex can easily be used as guidance for transmission planners in other regions. + +NOTE 2 – For the calculation of the following examples the algorithm of the E-Model has been taken from Recommendation G.107 [3] at the time of publication. In case a later revision of Recommendation G.107 [3] does show a refined version of the algorithm, the examples in this annex will still provide valid examples for tutorial purposes. For actual transmission planning tasks it should, in any case, be referred to the latest version of Recommendation G.107 [3]. + +NOTE 3 – Values for the equipment impairment factor ( $I_e$ ) in the following examples have been taken from Appendix I/G.113 [5] at the time of publication. In case a later revision of Appendix I/G.113 [5] does show different $I_e$ values for a specific codec, the examples in this annex will still provide valid examples for tutorial purposes. For actual transmission planning tasks it should, in any case, be referred to the latest version of Appendix I/G.113 [5]. + +### **B.1 Planning example for the European scenario** + +The following example will demonstrate how to perform transmission planning according to this Recommendation. This example is not representing an actual private network, but the structure, routing and further requirements of the user are assumed in such a way, that the most critical aspects of transmission planning can be shown. The example results in impairments requiring the use of echo control devices, thus the investigations necessary for the insertion of echo cancellers can be demonstrated. Furthermore, the example follows the planning steps as proposed in clause 11. + +#### **B.1.1 Description of the network and user's demand** + +The basic structure of the network is shown in Figure B.1. The network is serving a medium size company, operating only in a regional area and is consisting of four PBXs with digital switching + +matrix. PBXs A and B are serving approximately 500 extensions each, while the PBXs at the locations C and D are smaller equipment's for only 150 extensions. Both, digital and analogue telephone sets are used at all PBXs. + +![Figure B.1/G.108 – Basic structure of the private network](8f57d0f696133a7d3d0e75add566b6bc_img.jpg) + +Detailed description of Figure B.1/G.108: A network diagram showing four locations (A, B, C, D) interconnected in a mesh-like structure. + - Location A: Connected to 'Access to public network'. Linked to B (40 km, 80 channels), C (25 km, 35 channels), and D (45 km, 60 channels). + - Location B: Linked to A, D (5 km, 10 channels), and C (15 km, 15 channels). It includes a 'Cellular inhouse-network DECT standard' connected via a digital interface. + - Location C: Linked to A, B, and D (20 km, 15 channels). + - Location D: Linked to A, B, and C. + - Icons: A square with a handset represents a digital telephone; a simple handset represents an analogue telephone. Both types are shown at all locations. + - Legend: Analogue telephone (handset icon), digital telephone (handset in a square icon). + - Reference number: T1211340-99. + +**Figure B.1/G.108 – Basic structure of the private network** + +Figure B.1/G.108 – Basic structure of the private network + +All switching elements should be interconnected via 2 Mbit/s digital leased lines provided by the public network operator. The required number of channels between the different locations according to the traffic load and the average distances are given in Figure B.1. Between the locations A-B, A-C and A-D a high amount of data traffic should be taken into account. For these transmission elements an economical solution using data multiplexers with integrated low bit-rate coding for speech should be investigated. + +As a specific requirement by the user a cellular network, serving cordless telephones according to the DECT standard should be provided within the office building at location B. The interface between the fixed parts of this cellular network and the PBX in B is digital. + +Access to and from the public network is served only by the PBX at A. The interconnection is fully digital. According to the business of this company the predominance of communication partners are in the private domain, i.e. single telephone sets, connected to the public network. Although the company is operating in a regional area only, national long distance calls cannot be excluded. International calls, however, need not be considered. + +Basically there are no routing restrictions for internal connections or for connections to and from the public network. According to the "mesh" structure of the private network, rerouting in case of busy trunks via three PBXs should also be taken into account during planning. A rerouting via four PBXs (e.g. from A to B via C and D), however, is only exceptional and should not be considered. + +**B.1.2 Definition of reference configurations** + +When investigating the private network for a critical connection with respect to speech transmission quality, primarily connections via the public network should be considered. In this example the access to the public network is digital, only national long distance calls should be considered and the single telephone set with its average characteristics can be assumed as the far-end termination. The path through the public network is forming an echo path via the hybrid in the far-end local exchange. + +**Recommendation G.108 (09/99)**      83 + +For the most critical connection within this private network the use of low bit-rate equipment and the possibility of rerouting via three PBXs should be taken into account. Probably the cordless telephones at location B will contribute with higher impairments, mainly with echo effects, than digital or analogue wired telephones. Cordless telephones according to the DECT standard, however, are equipped with integrated echo control devices, hence, it becomes difficult to decide in advance, which telephone set will be more critical. Therefore, both reference configurations should be defined and investigated. For the first reference configuration the analogue and digital telephone sets connected to the PBX in C are selected, since a rerouting via the PBX in D to the PBX in A will (roughly estimated) contribute with more propagation time due to the length of the leased lines. The resulting reference configuration 1 is shown in Figure B.2. + +![Figure B.2/G.108 – Reference configuration 1. This diagram shows a network path starting from an analogue telephone and a digital telephone connected to PBX C. The path goes from PBX C to PBX D, then through a block of 'Low bit-rate equipment' to PBX A. From PBX A, it enters the 'Public network national long distance path', which consists of two more PBX units, and finally reaches a 'Far end termination'. A double-headed arrow labeled 'Echo path' is shown below the main path, indicating the return route from the far end termination back through the public network and PBXs to the telephones at PBX C. The diagram is labeled T1211350-99.](b76d1b06cf06e1c28f844e68507b40ed_img.jpg) + +Figure B.2/G.108 – Reference configuration 1. This diagram shows a network path starting from an analogue telephone and a digital telephone connected to PBX C. The path goes from PBX C to PBX D, then through a block of 'Low bit-rate equipment' to PBX A. From PBX A, it enters the 'Public network national long distance path', which consists of two more PBX units, and finally reaches a 'Far end termination'. A double-headed arrow labeled 'Echo path' is shown below the main path, indicating the return route from the far end termination back through the public network and PBXs to the telephones at PBX C. The diagram is labeled T1211350-99. + +**Figure B.2/G.108 – Reference configuration 1** + +Both types of telephone sets are included for a possible difference in impairments. This enables the planner to issue the quality estimation for all extensions in C using the same reference configuration. The configuration also contains the low bit-rate equipment between the PBXs in A and D. + +The second reference configuration is based on the cordless telephones of the cellular network in location B connected via the PBXs in D and A and the public network again to the single telephone at the far-end termination. The principle of this reference configuration 2 is drawn in Figure B.3. + +In both reference configurations impairments due to echo should be expected, caused not only by the low bit-rate equipment but also by the additional delay for cordless telephones. The effective echo path as shown in Figures B.2 and B.3 is comparable for both configurations. For the possible use of echo control devices both configurations should be considered together, to obtain an idea of which type of echo cancellers and which location must be selected, to serve the different terminal equipment both with the same device. + +![Figure B.3/G.108 – Reference configuration 2. This diagram shows a network path starting from a 'Cordless telephone (DECT)' connected to PBX B. The path goes from PBX B to PBX D, then through a block of 'Low bit-rate equipment' to PBX A. From PBX A, it enters the 'Public network national long distance path', which consists of two more PBX units, and finally reaches a 'Far end termination'. A double-headed arrow labeled 'Echo path' is shown below the main path, indicating the return route from the far end termination back through the public network and PBXs to the cordless telephone at PBX B. The diagram is labeled T1211360-99.](079326de347e985e278d2674647d17dc_img.jpg) + +Figure B.3/G.108 – Reference configuration 2. This diagram shows a network path starting from a 'Cordless telephone (DECT)' connected to PBX B. The path goes from PBX B to PBX D, then through a block of 'Low bit-rate equipment' to PBX A. From PBX A, it enters the 'Public network national long distance path', which consists of two more PBX units, and finally reaches a 'Far end termination'. A double-headed arrow labeled 'Echo path' is shown below the main path, indicating the return route from the far end termination back through the public network and PBXs to the cordless telephone at PBX B. The diagram is labeled T1211360-99. + +**Figure B.3/G.108 – Reference configuration 2** + +Although, in most cases, connections via the public network are more critical than internal connections, also routings within the private network should be taken into account. For the network in this example a critical configuration may arise when the cordless telephones at location B are connected with analogue or digital telephones in D via the PBX in A. In this case two low bit-rate equipment are connected in tandem (between B-A and A-D), contributing with delay and distortions, possibly requiring echo control devices also for internal calls. Therefore, a third reference configuration as shown in Figure B.4 is included into the planning. + +![Diagram of Reference configuration 3 showing a cordless telephone (DECT) connected to a PBX (B), which is connected via low bit-rate equipment to another PBX (A), which is connected via low bit-rate equipment to a third PBX (D), which is connected to an analogue telephone and a digital telephone. The diagram is labeled T1211370-99.](6834375fe386f94a73387a3e15eb8837_img.jpg) + +The diagram illustrates a network configuration. On the left, a 'Cordless telephone (DECT)' is shown with a signal arrow pointing to a rectangular box labeled 'B'. Box 'B' is connected to a central rectangular box labeled 'A' via a dashed line labeled 'Low bit-rate equipment'. Box 'A' is connected to a third rectangular box labeled 'D' via another dashed line labeled 'Low bit-rate equipment'. Box 'D' has two output lines: one leading to an 'analogue telephone' and another leading to a 'digital telephone'. The identifier 'T1211370-99' is located in the bottom right corner of the diagram. + +Diagram of Reference configuration 3 showing a cordless telephone (DECT) connected to a PBX (B), which is connected via low bit-rate equipment to another PBX (A), which is connected via low bit-rate equipment to a third PBX (D), which is connected to an analogue telephone and a digital telephone. The diagram is labeled T1211370-99. + +**Figure B.4/G.108 – Reference configuration 3** + +These three reference configurations are the basis now for the determination of the relevant parameter values of the different elements and the following planning calculations. If the results for these most critical configurations, including all necessary echo cancelling devices, are in a sufficient range for the expected quality, all other connections for this private network can be assumed to have less impairments. + +#### B.1.3 Determination of the transmission parameters + +According to the three reference configurations indicating all relevant elements the values for the different transmission parameters should be determined in the next step. This information is either known, or should be provided by network operators or by the suppliers of the equipment. For the defined reference configurations values should be determined for the far-end termination, for the public network, for leased lines and for the equipment to be used within the private network. + +#### *Far-end termination* + +For the far-end termination the single telephone set (private domain) was selected. The corresponding values can be taken from the description in A.3.1 with SLR = 8 dB and RLR = -3 dB. These values include an average subscriber line with a loss of 4 dB. However, for planning calculations and for the assignment to a working configuration for the E-Model the entire far-end termination can be considered as a telephone set. + +#### *Public network* + +From the public network operator the following information is provided: + +For the digital access to the public network a fully digital routing within the network up to the local exchange, serving the far-end termination, can be assumed for all local, regional and long distance calls. Depending on the location and access point of the private network, an average mean one-way delay between the access point and each terminating local exchange of 10 ms should be assumed. The hybrid at the termination is providing an average value of 24 dB for the weighted echo loss. This value is including a loss of 7 dB in the direction towards the far-end termination. There are no further losses or gains within the public network. + +##### *Leased lines* + +All leased lines provided by the public network operator are digital lines with a 2 Mbit/sec interface at both ends. The routing is bit-transparent in all cases. For the mean one-way delay the following actual values have been determined by the operator: + +| | | | | +|------|---------------|------|--------| +| Line | A-B, A-C, C-D | each | 1.0 ms | +| Line | A-D | | 1.5 ms | +| Line | B-C | | 0.8 ms | +| Line | B-D | | 0.5 ms | + +#### *Terminal elements in the private network* + +Three types of terminals, analogue, digital and cordless telephones are used throughout the network. They are in conformance with national requirements or European TBRs. For analogue terminals only modern types with electronic circuits and capacitive complex impedances are used. The relevant parameter values for transmission planning are listed below: + +Analogue telephones (For the purposes of this example the values below have been chosen): + +| | | | +|-------------------------|--------|--------------------------------------------------------| +| Send Loudness Rating | SLR | = +4 dB | +| Receive Loudness Rating | RLR | = -7 dB | +| Input impedance | $Z_R$ | = $270 \Omega + (750 \Omega \parallel 150 \text{ nF})$ | +| Balance impedance | $Z_B$ | = optimized for termination with $Z_R$ | +| Mean one-way delay | $\tau$ | = negligible | + +Digital telephones (according to [49]): + +| | | | +|---------------------------------|--------|-----------| +| Send Loudness Rating | SLR | = +7 dB | +| Receive Loudness Rating | RLR | = +3 dB | +| Terminal Coupling Loss weighted | TCLw | = > 46 dB | +| Mean one-way delay | $\tau$ | = 1.5 ms | + +Further parameters, in the E-Model assigned to a telephone set such as STMR, LSTR and the D-factor, can remain at their default values. For the analogue telephones this is guaranteed due to the correct impedance matching between the analogue telephone and the input impedance of the extension interfaces in the PBXs. + +Cordless telephones (according to [50]): + +The values are referred to the digital interface to the PBX in B, i.e. including portable and fixed part of the cordless telephone: + +| | | | +|---------------------------------|--------|---------------------------------------| +| Send Loudness Rating | SLR | = +7 dB | +| Receive Loudness Rating | RLR | = +3 dB | +| Mean one-way delay | $\tau$ | = 14 ms | +| Soft suppressor (fixed part) | | | +| additional echo loss | | 9 dB | +| hangover time | | 60 ms | +| Echo canceller | | not applicable for digital interfaces | +| Artificial echo loss | | available, but disabled | +| Terminal Coupling Loss weighted | TCLw | = 46 dB and optional 34 dB (see Note) | + +NOTE – Both types of portable parts should be assumed, however, signalling to the fixed part according to [50] is provided. + +##### Switching elements + +All the PBXs at the different locations are of the same type with a 64 kbit/s PCM switching matrix. Analogue interfaces are only available for analogue extensions. The insertion of digital loss or gain pads is possible and can be controlled depending on the types of interfaces connected. For analogue interfaces the following values are assumed: + +| | | +|-----------------------------|------------------------------------------------------| +| Relative input level (A/D) | 0 dBr | +| Relative output level (D/A) | –7 dBr | +| Input impedance | $270 \Omega + (750 \Omega \parallel 150 \text{ nF})$ | +| Balance impedance | $270 \Omega + (750 \Omega \parallel 150 \text{ nF})$ | +| Echo loss | 25 dB (for termination with $Z_R$ ) | + +The echo loss of 25 dB includes the receive loss of 7 dB. All further characteristics are according to national or European standards. The relative input and output levels of all digital interfaces are 0 dBr, if no digital loss or gain is used. For all connections including an analogue extension interface a digital loss of 3 dB is inserted by the switching matrix in both transmission directions. For the mean one-way delay a value of 1 ms (average value) can be assumed for planning purposes for each type of connection. + +The throughconnection by the switching matrix is only performed after termination (off-hook of the telephone set). All analogue telephone sets are using DTMF signalling, i.e. idle or short circuit with respect to stability should not be considered for this network. + +#### Low bit-rate equipment + +All low bit-rate (multiplexing) equipment are assigned to the digital leased lines and installed between the 2 MBit/s interfaces of the leased line and the PBX as shown in Figure B.5. The equipment is providing a speech compression using either 32 kbit/s or 24 kbit/s ADPCM. The corresponding equipment impairment factor values can be taken from Table 2a with: + +| | | +|---------------------------|------------| +| 32 kbit/s ADPCM equipment | $I_e = 7$ | +| 24 kbit/s ADPCM equipment | $I_e = 25$ | + +If two or more of this equipment is connected in tandem, where a decoding is performed for the through-connection via a PBX, the impairments should be added for each equipment in a connection. + +![Diagram showing the use of low bit-rate equipment for a leased line. Two PBX units are connected via a 'Leased line 2 Mbit/s'. Between each PBX and the leased line is a box labeled 'EC' (Integrated echo canceller) which is part of the 'Low bit-rate equipment'. The diagram shows the flow of signals from the PBX, through the EC, into the leased line, and back through the EC at the other end. A label 'T1211380-99' is present in the bottom right of the diagram area.](53f4e16be332aa0952e18cbb5259c31c_img.jpg) + +EC Integrated echo canceller + +Diagram showing the use of low bit-rate equipment for a leased line. Two PBX units are connected via a 'Leased line 2 Mbit/s'. Between each PBX and the leased line is a box labeled 'EC' (Integrated echo canceller) which is part of the 'Low bit-rate equipment'. The diagram shows the flow of signals from the PBX, through the EC, into the leased line, and back through the EC at the other end. A label 'T1211380-99' is present in the bottom right of the diagram area. + +Figure B.5/G.108 – Use of low bit-rate equipment for a leased line + +For more capacity on the leased lines a Voice Activity Detection (VAD) is used in addition to the ADPCM coding. This VAD should be considered due to additional delay. Since the total delay of such an equipment is too high for most of the applications, integrated echo cancellers are provided which can be disabled or enabled manually. The characteristics for such an equipment relevant for planning, provided by the supplier are as follows: + +| | | +|-------------------------------------------------|--------------------------------------| +| Mean one-way delay | 20 ms (with VAD for 32 or 24 kbit/s) | +| Loss between the two digital interfaces | 0 dB | +| Selection of coding | fixed | +| Recognition of fax signals with code adaptation | yes | + +The characteristics of integrated echo cancellers are (see also 10.2 and A.1.9): + +| | | +|----------------------------------------------------|----------| +| Minimum required echo loss (hybrid) | 6 dB | +| Echo loss (without NLP) | 25 dB | +| Residual echo level (with NLP) | -65 dBm0 | +| Threshold of the NLP | -36 dBm0 | +| Permitted echo path delay (twice the mean one-way) | 15 ms | +| Linear echo path required | yes | +| Convergence time | < 1 s | + +It should be noted, that these echo cancellers are, with the exception of the permitted echo path delay, nearly identical with those according to Recommendations G.165 [11] and G.168 [12]. + +#### B.1.4 End-to-end calculation with the E-Model + +After determining and collecting all necessary data, the calculations with the E-Model can now be executed. For this example the calculations are made for each of the three reference configurations separately. The configurations are illustrated in Figures B.6 through B.8 again, now also containing all relevant parameter values for a more clear identification of the input parameters to the E-Model. For all three configurations some parameters can already be excluded from the calculation, i.e. they will remain at their default values during calculation. + +As already mentioned, the parameters related to the telephone sets such as STMR, LSTR and the D-factors are not relevant due to correct impedance matching for the analogue sets and characteristics according to the relevant standards for the digital and cordless telephones. Default values can also be used for the parameters room noise at the send and receive side, since all telephones are installed in an office environment without extensive noise. Finally, also the number of quantization distortion units can remain at the default value of $qdu = 1$ if the digital telephone sets at C are investigated, since in all configurations one A/D-D/A conversion is active (independent of the ADPCM coding which is handled separately). If the analogue telephone sets at C are considered, a digital loss pad ( $qdu = 0.7$ ) is inserted, resulting in an input parameter of $qdu = 1.7$ . + +##### *Reference configuration 1* + +The Reference configuration 1 including all necessary parameter values and indicating the echo paths to be calculated is shown in Figure B.6. + +![Diagram illustrating the basis for calculation of reference configuration 1. It shows a network topology with a Private network (PBX C, D) and a Public network (national long distance path). The 0 dBr point is at the interface between the private and public network (PBX A). Echo paths 1 and 2 are shown. Parameters include SLR, RLR, and mean one-way delay.](a37adbbe12ec735a20ead2466363d07a_img.jpg) + +The diagram shows a network configuration for calculating reference configuration 1. It consists of a Private network (PBX C, D) and a Public network (national long distance path). The 0 dBr point is at the interface between the private and public network (PBX A). Echo paths 1 and 2 are shown. Parameters include SLR, RLR, and mean one-way delay. + +Key components and parameters: + +- 0 ms**: Start of the timeline. +- Private network**: Contains PBX C and D. PBX C has SLR = 4 dB, RLR = -7 dB, and SLR = 7 dB. PBX D has equipment 20 ms and line 1.5. +- 0 dBr point**: Located at the interface between the private and public network (PBX A). +- Public network**: National long distance path with a mean one-way delay of 10 ms. It includes a 24 dB echo loss. +- Far end termination**: Located at the end of the public network path, with RLR = -3 dB, 4 dB, and SLR = 8 dB. +- Echo path 1**: The path from the telephone in the private network to the far end termination and back. +- Echo path 2**: The path from the telephone in the private network to the 0 dBr point and back. +- Mean one-way delay in ms**: 1.5 ms for the leased line, 20 ms for low bit-rate equipment, and 10 ms for the public network. +- T1211390-99**: Reference number. + +Diagram illustrating the basis for calculation of reference configuration 1. It shows a network topology with a Private network (PBX C, D) and a Public network (national long distance path). The 0 dBr point is at the interface between the private and public network (PBX A). Echo paths 1 and 2 are shown. Parameters include SLR, RLR, and mean one-way delay. + +**Figure B.6/G.108 – Basis for calculation of reference configuration 1** + +For the calculation and definition of the actual input values to the E-Model, it is the first step to select one of the working configurations (see 9.2) in conjunction with the definition of the 0 dBr-point. In this actual configuration the 0 dBr-point is defined at the interface between private and public network (access interface of PBX A). + +The choice for the working configuration is depending on whether the analogue or the digital telephone set of the private network is considered. For impairments due to echo path 1, effective for both telephone sets, the telephone set of the private network should be assigned to the receive side of the working configuration. For investigation of echo path 2 the far-end termination is representing the receive side in the E-Model. + +The parameters relevant for echo path 1 should be determined in a pre-calculation. It is important to note, that the total mean one-way delay of the leased line between A and D is composed of a delay of 20 ms for the low bit-rate equipment and of 1.5 ms for the leased line itself. + +The TELR can be calculated as follows: + +| | analogue telephone | digital telephone | +|----------------------------------|---------------------------|--------------------------| +| SLR of telephone | 4 dB | 7 dB | +| hybrid loss in C (transmit path) | 0 dB | – | +| digital pad in C (transmit path) | 3 dB | 0 dB | +| echo loss in public network | 24 dB | 24 dB | +| digital pad in C (receive path) | 3 dB | 0 dB | +| hybrid loss in C (receive path) | 7 dB | – | +| RLR of telephone | –7 dB | 3 dB | +| TELR | 34 dB | 34 dB | + +The WEPL can be calculated as follows: + +| | analogue telephone | digital telephone | +|-----------------------------------|---------------------------|--------------------------| +| TCLw of the digital telephone set | – | 46 dB | +| echo loss (analogue telephone) | 25 dB | – | +| digital pad in C (transmit path) | 3 dB | 3 dB | +| digital pad in C (receive path) | 3 dB | 3 dB | +| echo loss in public network | 24 dB | 24 dB | +| WEPL | 55 dB | 76 dB | + +The mean one-way delay T for echo path 1 is obtained by simply adding all single values along the reference configuration in Figure B.6; and because the echo sources are at both ends of the connection, the delay parameters can be calculated as follows: $T_a = T$ and $T_r = 2 T$ . The result is + +analogue telephone $T = 35.5$ ms; + +digital telephone $T = 37.0$ ms. + +The values are only slightly different in the delay between analogue and digital telephone as expected. In a further pre-calculation the SLR and RLR referred to the defined 0 dBr-point should be determined as the final input parameters. For the telephones in the private network, assigned to the receive side of the E-Model, only RLR should be available. The value is obtained with $RLR = 3$ dB for both telephones. For the SLR the path between the far-end termination (send side) and the 0 dBr-point is relevant. The corresponding result is $SLR = 8$ dB. + +The remaining impairment to be determined for this example is the equipment impairment factor ( $I_e$ ). The reference configuration 1 is containing the low bit-rate equipment between the PBXs in A and D. The used coding is ADPCM with a bit-rate of 32 or 24 kbit/s. According to Table 2a the corresponding values are $I_e = 7$ for 32 kbit/s and $I_e = 25$ for 24 kbit/s. These values can be used directly as input parameters. Both values should be subject to planning. + +Before performing the calculation run with the E-Model the following input parameters should be set for reference configuration 1. All other input parameters should be set to their default values as given in Table 4. + +$SLR = 8$ dB + $RLR = 3$ dB + $TELR = 34$ dB (for both telephones) + $WEPL = 55$ dB (for analogue telephones) + $WEPL = 76$ dB (for digital telephones) + $T = 35.5$ ms (for analogue telephones) + $T = 37.0$ ms (for digital telephones) + $T_a = 35.5$ ms (for analogue telephones) + $T_a = 37.0$ ms (for digital telephones) + $T_r = 71$ ms (for analogue telephones) + $T_r = 74$ ms (for digital telephones) + $I_e = 7$ (for 32 kbit/s ADPCM equipment) + $I_e = 25$ (for 24 kbit/s ADPCM equipment) + $qdu = 1.7$ (for analogue telephones) + $qdu = 1$ (for digital telephones, equal to the default value) + +To reduce the number of calculations the parameters $T$ and $T_a$ can be averaged to $T = T_a = 36$ ms (consequently, $T_r$ is set to 72 ms) and the number of qdu can be left at the default value, since there will be no difference in the results for values of less than $qdu = 4$ (see also 7.5). + +The result for the calculation for reference configuration 1 (with analogue telephone set) with the E-Model is shown below for the E-Model Rating $R$ , the separate impairment values for $I_s$ , $I_d$ and $I_e$ . It should be noted, that with the digital telephone set the E-Model Rating $R$ increases by $\Delta R = 0.5$ due to the higher value for WEPL. + +| | R | $I_s$ | $I_d$ | $I_e$ | +|--------------------------------|-------------|-------|-------|-------| +| with 32 kbit/s ADPCM equipment | 60.1 | 0.3 | 26.1 | 7 | +| with 24 kbit/s ADPCM equipment | 42.1 | 0.3 | 26.1 | 25 | + +In a first analysis the results for the E-Model Rating $R$ are too low in both cases. Examining the separate values, mainly for $I_d$ the sum for impairments due to echo and $I_e$ for equipment impairments, the major impairment is caused by delay for 32 kbit/s ADPCM equipment. The same impairment is contributing in addition when 24 kbit/s ADPCM equipment is used. The high value for $I_d$ can be reduced if echo control devices are used. In this case also the value for $R = 42.1$ would be increased, but still remaining below 70, a range which should be avoided for standard connections. Standard connection means that all subscribers at the locations B, C and D would perceive a quality only in a medium range for every call to and from the public network. Therefore, as a rough estimate it can be decided to exclude the use of 24 kbit/s ADPCM. + +For the benefit of the far-end termination with respect to echo effects also the requirements at the interface between public and private network should be investigated as described in 7.9. The required loudness rating values provided by the private network at the interface with $SLR \geq 7$ dB and $RLR \geq 3$ dB are met. Also the echo loss of $\geq 24$ dB is guaranteed with 31 dB (25 dB of the hybrid in C and $2 \times 3$ dB digital loss in C). However, these values are restricted for networks with a mean one-way delay of less than 5 ms. For reference configuration 1, however, this value is 25.5 ms and a calculation for echo path 2 (see Figure B.6) becomes necessary. + +For the execution of this calculation, only the analogue telephone set in the private network should be considered, since the TELR will in any case be lower (i.e. more critical) than with a digital telephone terminating the echo path with a $TCL_w$ of 46 dB. For the working configuration the 2-wire/2-wire connection according to Figure 16 can be used where the interface between public and private network again is used as the 0 dBr-reference point. The far-end termination should now be assigned to the receive side of the E-Model. + +For pre-calculations the reference configuration of Figure B.6 can be used. The $SLR$ (now for the analogue set in the private network) up to the reference point, is the sum of the set and the digital pad in C resulting in $SLR = 7$ dB. The $RLR$ of the far-end termination is including the value of the far-end termination and the receive loss of 7 dB in the local exchange with a sum of $RLR = 4$ dB. + +The parameters $T$ and $TELR$ for the echo path 2 can be added along the echo path as shown in Figure B.6. The mean one-way delay is $T = 35.5$ ms, identical with echo path 1. The summation for $TELR$ is: + +| | | +|--------------------------------------------------------|--------------| +| SLR of the far-end termination | 8 dB | +| Hybrid loss in the local office | 0 dB | +| Digital pad in C | 3 dB | +| Echo loss of the hybrid in C (incl. 7 dB receive loss) | 25 dB | +| Digital pad in C | 3 dB | +| Hybrid loss in the local office | 7 dB | +| RLR of the far-end termination | -3 dB | +| TELR | 43 dB | + +All other input values can either be left at their default values or have the same setting as for echo path 1. For the equipment impairment value, only the 32 kbit/s ADPCM equipment is considered. The input parameters are: + +| | | | +|------|---|-----------------------------------| +| SLR | = | 7 dB | +| RLR | = | 4 dB | +| TELR | = | 43 dB | +| WEPL | = | 55 dB | +| T | = | 35.5 ms | +| Ta | = | 35.5 ms | +| Tr | = | 71 ms | +| Ie | = | 7 (for 32 kbit/s ADPCM equipment) | + +The result of the calculation for the far-end termination is: + +| R | Is | Id | Ie | +|-------------|-----|------|----| +| 76.3 | 0.3 | 10.1 | 7 | + +With this value for the E-Model Rating R of 76.3, the subscriber at the far-end termination can expect higher quality than the subscriber in the private network. However, even this value could be further improved if the corresponding echo control devices are also provided for the far-end termination. + +##### *Reference configuration 2* + +The procedure, the definition of the 0 dBr-point and the calculations for reference configuration 2 are similar to reference configuration 1. The only difference between these two configurations is within the private network, now considering a cordless telephone connected to the PBX in B as shown in the detailed configuration of Figure B.7. + +For the quality estimate of the private network, the cordless telephone should be assigned to the receive side of the E-Model in the first investigation. In this case the working configuration for 2-wire/4-wire connections of Figure 19 can be used. Also the impairments for the far-end termination mainly with respect to echo should be considered here in a second investigation. The major impairments in this configuration can be expected due to delay and distortion caused by the use of ADPCM coding. Other parameters as described for reference configuration 1 can be left at their default values or are not relevant in this configuration. + +![Figure B.7/G.108 – Basis for calculation of reference configuration 2](5dd117defe429c6c5620c4bb9ce20b0a_img.jpg) + +The diagram illustrates a reference configuration for echo calculation. It shows a signal path from a cordless handset on the left through a private network (Red privada) and a public network (Red pública) to a far-end termination. Key components include: + + +- Cordless Handset:** SLR = 7 dB, RLR = 3 dB. +- Private Network:** Includes blocks B, D, and A with associated delays (14 ms, 1 ms, 0.5 ms, 1 ms). Block B has an artificial echo loss (AE) of 24 dB. There is a low bit-rate equipment block (Equipo de baja velocidad binaria) with a 20 ms delay and a 1.5 ms line. +- Public Network:** Includes a 0 dBr point, a national long-distance path with a 10 ms delay, and a 24 dB loss block. +- Far-end Termination:** RLR = -3 dB, SLR = 8 dB, and a 4 dB loss pad. +- Echo Paths:** 'Trayecto de eco 1' covers the path back from the public network. 'Trayecto de eco 2' covers the path back from the far-end termination. + +**Figure B.7/G.108 – Basis for calculation of reference configuration 2** + +Figure B.7/G.108 – Basis for calculation of reference configuration 2 + +The pre-calculation for the loudness rating values is equal to configuration 1 for the investigation of the digital telephone and resulting in SLR = 8 dB (far-end termination) and RLR = 3 dB (no digital pads are enabled in PBX B). The artificial echo loss AE in B shown in Figure B.7 (if enabled, it is effective for the subscriber at the far-end termination, only) is disabled for the present. + +The parameters for echo path 1 are again determined for the mean one-way delay T by a simple addition with T = 49 ms, which is equal to the absolute delay Ta. For the TELR within echo path 1 a specific characteristic of the cordless telephone, the soft suppressor (SS), should be taken into account. The SS is set to an additional loss of 9 dB and is enabled during talking. This can also be interpreted for the calculation of TELR as an increase of the RLR of the cordless telephone. The RLR to be used for the calculation of TELR then is RLR = 3 dB + 9 dB = 12 dB. Since there is no further loss neither within the private (no digital loss pads in B) nor in the public network, only the echo loss in the local exchange and the loudness ratings of the cordless telephone with SLR = 7 dB and RLR = 12 dB are contributing to the echo path loss with TELR = 43 dB. + +For impairments caused by listener echo and for echo path 2 the artificial echo loss AE with 24 dB is assumed to be enabled, since this will result in a lower value for WEPL and TELR (of echo path 2) then the TCLw of the cordless telephone set. In this case, for the round-trip delay (Tr), the delay segments have to be taken into account only, which occur within the 4-wire loop, i.e. the delay of 14 ms caused by the cordless telephone set is excluded; hence Tr = 2 × 35 ms = 70 ms. For the calculation of the WEPL the echo loss of the far-end termination with 24 dB and the AE with 24 dB have to be considered only, resulting in WEPL = 48 dB. + +For the equipment impairment factor, the 32 kbit/s ADPCM coding is used twice, resulting in a total value of Ie = 14. The input values to the E-Model for calculation of reference configuration 2 are: + +$\text{SLR} = 8 \text{ dB}$ + +$\text{RLR} = 3 \text{ dB}$ + +$\text{TELR} = 43 \text{ dB}$ + +$\text{WEPL} = 48 \text{ dB}$ + +$\text{T} = 49 \text{ ms}$ + +$\text{T}_a = 49 \text{ ms}$ + +**Recommendation G.108 (09/99)**      93 + +Tr = 70 ms + +Ie = 14 (for two times 32 kbit/s ADPCM) + +with all other parameters set to their default values. The result of the calculation is: + +| R | Is | Id | Ie | +|-------------|-----|------|----| +| 64.5 | 0.3 | 15.3 | 14 | + +In a first analysis this result with the E-Model Rating R = 64.5 is considered as too low as well, since all subscribers using cordless telephones would perceive only medium quality for each call to and from the public network, which seems to be unacceptable. Additional echo control devices should also be provided for this type of connections. + +For the investigation of the perceived quality for the far-end termination, echo path 2 as shown in Figure B.7 should be considered and also the equipment impairments which are caused by 32 kbit/s ADPCM equipment disturbing the far-end termination too. The far-end termination is assigned now again to the receive side of the E-Model corresponding to the working Configuration for 4-wire/2-wire connections of Figure 17. The input parameters for loudness rating are SLR = 7 dB and RLR = 4 dB. + +When preparing the input parameters mean one-way delay T and TELR, two different configurations at the cordless telephone with respect to echo should be taken into account. First, the portable part of the cordless system can provide a TCLw of > 46 dB (this option is not indicated in Figure B.7 with respect to the echo path). Now the TELR is formed by the SLR = 8 dB and RLR = -3 dB of the far-end termination, the 7 dB receive loss in the hybrid of the local office and the TCLw of 46 dB resulting in a value of TELR = 58 dB. This value is nearly identical with the use of an echo canceller independent of the amount of mean one-way delay in the entire echo path. + +The portable part of the cordless telephone may however also provide a TCLw of only 34 dB as an option. In this situation usually the artificial echo loss AE in PBX B is enabled, terminating the connection with a fixed echo loss of 24 dB, but excluding the delay of 14 ms from the cordless system (this configuration is shown in Figure B.7 and indicated by echo path 2). The whole mean one-way delay T of echo path 2 is T = 35 ms; while the absolute delay Ta remains at its value of 49 ms. The TELR can be calculated with 36 dB, while the values of the round-trip delay Tr = 70 ms and of WEPL = 48 dB remain unchanged. For the equipment impairment factor the same value of Ie = 14 is effective as for the subscriber of the private network. The input parameters for the E-Model are: + +SLR = 7 dB + +RLR = 4 dB + +TELR = 36 dB + +WEPL = 48 dB + +T = 35 ms + +Ta = 49 ms + +Tr = 70 ms + +Ie = 14 (for two times 32 kbit/s ADPCM) + +with all other parameters set to their default values. The result of the calculation is: + +| R | Is | Id | Ie | +|-------------|-----|------|----| +| 57.7 | 0.3 | 21.7 | 14 | + +This result of E-Model Rating $R = 57.7$ may be already considered as low quality and should not be accepted for the benefit of the subscriber at the far-end termination, i.e. echo control devices should be inserted, since here the major impairment with $I_d = 21.7$ is caused by echo as well. + +##### Reference configuration 3 + +For the investigation of an internal connection completely within the private network, the most critical configuration is expected for a routing between a cordless telephone at PBX B to an analogue or digital wired telephone in location D with a re-routing via PBX in A and, therefore, containing two leased line sections and the airpath where all three sections are using uncorrelated ADPCM coding. The reference configuration as the basis for this planning task is shown in Figure B.8. + +![Diagram of reference configuration 3 showing a network topology with PBXs A, B, and D, cordless and wired telephones, and echo paths.](d04c50badc78d5ba47bf4e352af4a754_img.jpg) + +The diagram illustrates a network configuration for echo path analysis. It features three PBX units: PBX B on the left, PBX A in the center, and PBX D on the right. + +At PBX B, a cordless telephone is connected with a Send Loudness Rating (SLR) of 7 dB and a Receive Loudness Rating (RLR) of 3 dB. The PBX itself has an Artificial Echo (AE) loss of 24 dB. + +PBX B is connected to PBX A via 'line 1', which includes 'equipment' with a 20 ms delay. + +PBX A is connected to PBX D via 'line 1.5', also with 'equipment' and a 20 ms delay. + +At PBX D, there are two types of terminations: + +- A cordless telephone with SLR = 4 dB and RLR = 3 dB. + +- An analogue or digital wired telephone with SLR = 7 dB. + +The PBX D unit is shown with internal components labeled 3, 7, and 3. + +A '0 dBr point' is marked at the center of PBX A. + +Two echo paths are identified: + +- 'Echo path 1' is the round-trip path from PBX B to PBX D and back. + +- 'Echo path 2' is the round-trip path from PBX B to PBX A and back. + +A 'Mean one-way delay in ms' is indicated for the path to PBX D, with a value of 1.5 ms shown near the end. + +The diagram is labeled 'T1211410-99' at the bottom right and 'AE Artificial echo loss' at the bottom left. + +Diagram of reference configuration 3 showing a network topology with PBXs A, B, and D, cordless and wired telephones, and echo paths. + +**Figure B.8/G.108 – Basis for calculation of reference configuration 3** + +For this investigation some assumptions can be made. For the termination in B cordless telephones with a TCLw of 34 dB and consequently an enabled artificial echo loss AE is assumed, since this will in any case be more critical than a TCLw of 46 dB with respect to TELR in echo path 2. For the terminals at PBX in D analogue telephones are considered, because the provided echo loss of 25 dB for a hybrid will result in lower values for TELR in echo path 1 than a digital telephone with $TCL_w = 46$ dB. + +For this configuration it is obvious that the use of 24 kbit/sec ADPCM shall be excluded. All other assumptions with respect to the different parameters are the same as in the previous configurations. The investigations and necessary calculations should be performed for both sides of the configuration. + +For the quality estimation of the cordless system, this telephone should be assigned to the receive side of the E-Model along with the working configuration of Figure 18. The 0 dBr-point in this configuration can be defined as a "virtual" reference point in the centre of PBX A, to obtain a nearly symmetrical configuration. The loudness rating values are $SLR = 7$ dB (including digital loss of 3 dB in PBX D) and $RLR = 3$ dB (without the effect of the soft suppressor). The mean one-way delay $T$ along echo path 1 as indicated in Figure B.8 is $T = 59.5$ ms, which is equal to $T_a$ . For the calculation of TELR an echo loss of 25 dB for the hybrid and the digital pads of 3 dB each in the PBX in D should be included. Furthermore, the soft suppressor in the receive path with a loss of 9 dB is contributing to the TELR. The result is $TELR = 50$ dB. + +For impairments caused by listener echo, and for echo path 2, the artificial echo loss (AE) with 24 dB should be considered again. Then the round-trip delay $T_r$ is calculated, as before, excluding the delay caused by the cordless telephone set and results to $T_r = 91$ ms. The WEPL includes the echo loss of 25 dB for the hybrid and the digital pads of 3 dB each in the PBX in D together with the artificial echo loss AE of 24 dB, resulting in $WEPL = 55$ dB. For the calculation of the equipment impairment factor, a 32 kbit/sec ADPCM coding is to be considered in three different sections cumulating to a value of $I_e = 21$ . While all other parameters are at default, the input parameters to be set are as follows: + +SLR = 7 dB + RLR = 3 dB + TELR = 50 dB + WEPL = 55 dB + T = 59.5 ms + $T_a$ = 59.5 ms + $T_r$ = 91.0 ms + $I_e$ = 21 (for three times 32 kbit/sec ADPCM) + +The result of the calculation is: + +| R | $I_s$ | $I_d$ | $I_e$ | +|-------------|-------|-------|-------| +| 65.6 | 0.5 | 8.5 | 21 | + +For the opposite direction the digital telephone at D is chosen for this investigation (1.5 ms additional delay) and is assigned to the receive side and a working configuration according to Figure 19 can be used. The loudness rating values are again $SLR = 7$ dB and $RLR = 3$ dB. For the mean one-way delay $T$ along echo path 2 of Figure B.8, the 14 ms of the cordless system are not included due to the artificial echo loss. However, contrary to the previous calculation, additional 1.5 ms should be taken into account for the digital telephone. The total value is then calculated with $T = 47$ ms and the round-trip delay $T_r$ is exactly twice this value, $T_r = 94$ ms. The absolute delay includes the delay caused by the cordless telephone, resulting to $T_a = 61$ ms. + +For the corresponding TELR, only the AE and the sum of SLR and RLR of the telephone in D is contributing with a result of $TELR = 34$ dB. The WEPL includes the TCLw of the digital telephone set with 46 dB and the artificial echo path of the cordless telephone set with 24 dB, resulting in $WEPL = 70$ dB. For the impairments due to ADPCM, coding the same value of $I_e = 21$ as before should be applied. The input parameters to be set are as follows with all other parameters at default: + +SLR = 7 dB + RLR = 3 dB + TELR = 34 dB + WEPL = 70 dB + T = 47 ms + $T_a$ = 61 ms + $T_r$ = 94 ms + $I_e$ = 21 (for three times 32 kbit/sec ADPCM) + +The result of the calculation is: + +| R | Is | Id | Ie | +|-------------|-----------|-----------|-----------| +| 41.6 | 0.5 | 31.8 | 21 | + +#### B.1.5 Analysis of the results + +For a better overview all results of the different calculations for the three reference configurations are summarized in Table B.1 for the E-Model Rating R and for the main impairment values Id and Ie, and for both sides of the connections, where opposite termination means the subscriber at PBX D for the reference configuration 3. + +**Table B.1/G.108 – Summary of the calculation results** + +| Reference configuration | Private network | | | Opposite termination | | | +|--------------------------------|------------------------|-----------|-----------|-----------------------------|-----------|-----------| +| | R | Id | Ie | R | Id | Ie | +| 1 | 60.1 | 26.1 | 7 | 76.3 | 10.1 | 7 | +| 2 | 64.5 | 15.3 | 14 | 57.7 | 21.7 | 14 | +| 3 | 65.6 | 8.5 | 21 | 41.6 | 31.8 | 21 | + +The results for the expected quality for the different configurations is varying in a wide range from a value of E-Model Rating R = 76.3, which would be judged according to Table 1 as medium quality category, to a value of R = 41.6 which is already below the recommended lower limit for R. Most of the values are in a range from 60 to 70 which is in the low quality category, only, and may at the lower values cause complaints. It should be noted that according to Table 1 in this category of low speech transmission quality many users will be dissatisfied. The major impairments for these reference configurations are due to echo and equipment impairment caused by the use of 32 kbit/s ADPCM equipment. Considering the results in Table B.1, the previous decision to avoid the use of 24 kbit/s ADPCM in the low bit-rate equipment is now confirmed again, since all Ie values would be increased and shifted into the range between Ie = 25 and Ie = 50. + +The low values for the E-Model Rating R appear not only in conjunction with calls to and from the public network but also for certain calls within the private network. When examining the values, especially the separate values for Id and Ie, it can be seen, that in most cases the impairments due to echo are contributing with a high amount. As a rough estimate the values for Id can be assumed to be reduced nearly to Id = 0 if echo control devices are used. This would also improve the E-Model Rating R by nearly the amount of the current Id value. For confirmation the calculations should be executed again with inserted echo control devices. + +For this private network it is, therefore, necessary to use echo cancellers. The selection of the correct echo cancellers and their location should provide echo control not only for internal calls, but also for calls to and from the public network and should be effective also for the opposite termination. + +#### B.1.6 Application of echo cancellers + +When once the decision has been made to use echo cancellers within the private network, the investigations should include an analysis of the characteristics of the echo cancellers also with respect to their type of application and location. Further information about the use of echo cancellers and all necessary characteristics, which should be taken into account, is available in detail in clause 10, and in A.1.9. + +When investigating the use of echo control devices in this private network the following problems should be cleared and rules should be considered (see also clause 10): + +- echo control should be provided for both talkers of a connection; +- information should be available if echo cancellers are provided within the public network and on their application and characteristics; +- echo cancellers should be located as close as possible to the echo source (e.g. hybrids); +- the permitted echo path delay of the canceller should be sufficiently higher than the actual echo path delay; +- the echo path should be linear. + +According to the information given by the public network operators and the suppliers of equipment in conjunction with the determination of parameters (see B.1.3), no echo cancellers are inserted within the public network in national long distance calls. Furthermore, the low bit-rate equipment is already equipped with integrated echo cancellers, which can be enabled or disabled. In a first step these cancellers should be taken into account for a possible use. + +Integrated echo cancellers are available on both ends of each of the three leased lines from A to B, C and D, located close to the leased line interfaces in the PBXs. In this case the echo path is formed only by the path through the PBX with a delay of 1 ms and the hybrid, connecting the analogue telephone set. Also in case of a re-routing, e.g. extension in D is routed via C to A, the echo path delay for the canceller in C is only increased by the additional paths through PBX C with 1 ms and the leased line between C and D with 1 ms. The actual echo path delay of $2 \times 3 \text{ ms} = 6 \text{ ms}$ is sufficiently below the permitted delay of the integrated cancellers of 15 ms. As already stated during the determination of equipment characteristics these integrated cancellers can be assumed to follow Recommendation G.165 [11] in all other relevant values. Therefore, as a first decision all integrated echo cancellers at the ends of the leased lines in location B, C and D will be enabled. This guarantees proper echo control for all far-end talkers (including the far-end termination via the public network) when being connected with any extension in B, C or D. + +The next question is, how to protect the talkers at the extensions in B, C and D themselves. For all internal connections between telephones in B, C and D, routed via A, this is guaranteed by the same equipment. For calls to and from subscribers in A and into the public network, however, there is no echo control up to now. For connections with telephones in A the integrated echo cancellers at the ends of the leased lines in A could be enabled. The leased lines between A and all other locations are carrying not only internal traffic but also traffic between the public network and all extensions in B, C and D. The echo path delay via the public network is higher than the permitted echo path delay of the integrated cancellers which is 15 ms only, therefore, these cancellers cannot be used with respect to the echo via the public network. + +To solve this problem, separate echo cancellers with characteristics according to the requirements of the public network shall be used. They can be inserted in PBX A, directly at the interface to the public network. However, to avoid a tandeming, the integrated echo cancellers at A should be disabled. These decisions on the application of echo cancelling devices is illustrated in Figure B.9. + +The separate echo cancellers at the public network interface are only necessary for connections to extensions in B, C and D (routed in any case via an additional delay of 20 ms) but not to A. If they remain inserted in the latter case, their impact is negligible. If possible, a more economical solution is to provide a "pool" for these cancellers, i.e. only calls between the leased line interfaces and the public network are routed via an echo canceller in the pool, while extensions in A are bypassing this pool. + +![Diagram showing the application of echo control devices in a private network. It features four main components: A (Public network interface), B (Cellular inhouse-network DECT standard), C, and D. Echo cancellers (EC) are shown at various points. At B, an arrow points to the interface with the text 'artificial echo loss 24 dB for TCLw 34 to 46 dB, soft suppressor 9 dB'. At A, three echo cancellers are shown with an 'X' over them, indicating they are disabled. At B, C, and D, echo cancellers are shown with arrows indicating the direction of the echo path. A legend at the bottom left defines the symbols: EC for Echo canceller, an arrow for the direction of the echo path, and an X for an integrated echo canceller disabled. The diagram is labeled T1211420-99.](c93c4b33a2b42c8dd6d82a354f2f89f1_img.jpg) + +Interface of fixed part +with: +artificial echo loss 24 dB +for TCLw 34 to 46 dB, +soft suppressor 9 dB + +``` + + +-------+ +---------------------------------+ + | | | Cellular | + | B |-------| inhouse-network | + | | | DECT standard | + +---+---+ +---------------------------------+ + | ^ + | | (Interface of fixed part) + | | + +---+---+ +---+---+ +-------+ Public network + | | | | | | | + | D |-------| C |-------| A |-------o + | | | | | | | + +-------+ +-------+ +-------+ | + | | | | + +---------------+---------------+-----------+ + +Legend: +EC Echo canceller +→ Direction of echo path +X Integrated echo canceller disabled + +``` + +EC Echo canceller +→ Direction of echo path +X Integrated echo canceller disabled + +T1211420-99 + +Diagram showing the application of echo control devices in a private network. It features four main components: A (Public network interface), B (Cellular inhouse-network DECT standard), C, and D. Echo cancellers (EC) are shown at various points. At B, an arrow points to the interface with the text 'artificial echo loss 24 dB for TCLw 34 to 46 dB, soft suppressor 9 dB'. At A, three echo cancellers are shown with an 'X' over them, indicating they are disabled. At B, C, and D, echo cancellers are shown with arrows indicating the direction of the echo path. A legend at the bottom left defines the symbols: EC for Echo canceller, an arrow for the direction of the echo path, and an X for an integrated echo canceller disabled. The diagram is labeled T1211420-99. + +**Figure B.9/G.108 – Application of echo control devices in the private network** + +For the cordless telephones in B, the artificial echo loss should be enabled for connections to those portable parts with $TCL_w = 34$ dB. This is providing an "in range" operation of the integrated echo cancellers at B. The soft suppressor is not necessary in principle, since all critical echo paths with higher delay are now equipped with echo cancellers, but the echo impairments can be reduced in case of direct connections to extensions in A (echo cancellers at A disabled), and to extensions in C and D via the direct routing without echo control devices. + +The only problem remaining are connections to analogue extensions in A. For talkers at B, C and D there is no echo control available due to the integrated cancellers at A being disabled. It is not possible to enable these cancellers by different reasons, as due to the need of avoiding tandeming with the separate cancellers, due to the non-linear echo path and due to exceeding the maximum permitted echo tail length for such a canceller. Therefore, it should be investigated whether the pool of echo cancellers can be used also for the internal connections to the analogue extensions in A, or the exclusive use of digital extensions in A should be taken into account. + +These investigations on the correct application of echo control devices in this network should be confirmed finally by calculations for all possible types of calls within the network, to and from the public network, mainly including the cordless telephones at B. These calculations are not executed here. When performing these calculations now, the input parameters for the mean one-way delay $T$ and for the talker echo loudness rating $TELR$ of the echo path can be set to their default values of $T = 0$ and $TELR = 65$ dB. + +With respect to the results summarized in Table B.1 for all reference configurations, it can be assumed with sufficient accuracy, that all values for the E-Model Rating $R$ are improved by the amount of the $I_d$ values. The only impairments remaining are the equipment impairments ( $I_e$ ), which can be up to $I_e > 21$ for reference configuration 3. However, it should be noted, that this configuration was defined as a critical connection including a re-routing with an additional low bit-rate section. Depending on other features of this private network, these re-routing will not necessarily be the "standard" routing for most of the calls. + +### B.2 Planning example for the North American scenario + +The following examples will demonstrate how to perform transmission planning of private networks in North America according to the principles of this Recommendation. + +#### B.2.1 Definition of reference configurations + +As in clause B.1, the analysis of North American scenarios addresses connections between the private and public network, with digital access lines interconnecting the networks, far-end terminations consisting of telephones with average characteristics, and the use of low bit rate equipment in the private network (the most critical connection case). The path through the public network forms an echo path via the hybrid in the far-end local exchange. The resulting reference configuration 1 is shown in Figure B.10. The connections are patterned after the network in Figure B.1. + +![Figure B.10/G.108 – Reference configuration 1 diagram](b30e390cb591b39482fe7ecd4c4cd84b_img.jpg) + +This diagram illustrates 'Reference configuration 1' for transmission planning. It is divided into two main sections: 'Private network' on the left and 'Public network' on the right, separated by a vertical dashed line. In the private network, an 'analogue telephone' and a 'digital telephone' are connected to a component labeled 'C'. Component 'C' is connected to component 'D', which in turn connects to a dashed box labeled 'Low bit-rate equipment'. This equipment connects to component 'A'. Component 'A' is connected to the public network side. On the public network side, there are two more unlabeled rectangular components in series, leading to a 'Far end termination' represented by a telephone icon. Below the diagram, a double-headed arrow labeled 'Echo path' spans from the analogue telephone, through the public network, and back. The text 'T1211430-99' is located in the bottom right corner. + +Figure B.10/G.108 – Reference configuration 1 diagram + +**Figure B.10/G.108 – Reference configuration 1** + +Cordless telephones, mainly due to the added delay, affecting echo performance, can result in higher impairments on an interconnection. Thus, an analysis is made of scenarios with different types of cordless telephones, segregated by the amount of delay contribution. The reference connection is shown in Figure B.11. + +![Figure B.11/G.108 – Reference configuration 2 diagram](98d9a07b2cfa04ebea4e5a4b556d184a_img.jpg) + +This diagram illustrates 'Reference configuration 2' for transmission planning. It follows a similar structure to Figure B.10, with 'Private network' and 'Public network' sections. In the private network, a 'Cordless telephone' is connected to a component labeled 'B'. Component 'B' connects to component 'D', which connects to a dashed box labeled 'Low bit-rate equipment'. This equipment connects to component 'A', which then connects to the public network. The public network contains two unlabeled rectangular components leading to a 'Far end termination' (telephone icon). A double-headed arrow labeled 'Echo path' is shown below, spanning from the cordless telephone. The text 'T1211440-99' is located in the bottom right corner. + +Figure B.11/G.108 – Reference configuration 2 diagram + +**Figure B.11/G.108 – Reference configuration 2** + +For comparison with the above connection and consistency with the analysis in B.1, a private network scenario, involving a cordless telephone at one end and low bit-rate equipment on a tandem connection, is also examined. The reference connection is shown in Figure B.12. + +![Diagram of Reference configuration 3 showing a cordless telephone connected to a cordless base station (B), which is connected via a dashed line representing low bit-rate equipment to a digital exchange (A). This is further connected via another dashed line representing low bit-rate equipment to a digital exchange (D). From exchange D, two lines lead to an analogue telephone and a digital telephone. The diagram is labeled T1211450-99.](54a1e5d91d7f442361767b1f8c81c777_img.jpg) + +Diagram of Reference configuration 3 showing a cordless telephone connected to a cordless base station (B), which is connected via a dashed line representing low bit-rate equipment to a digital exchange (A). This is further connected via another dashed line representing low bit-rate equipment to a digital exchange (D). From exchange D, two lines lead to an analogue telephone and a digital telephone. The diagram is labeled T1211450-99. + +**Figure B.12/G.108 – Reference configuration 3** + +These three reference configurations are now the basis for the determination of the relevant parameter values of the different elements and the following planning calculations. If the results for these most critical configurations, including all necessary echo cancelling devices, are in a sufficient range for the expected quality, all other connections for this private network can be assumed to have less impairments. + +#### **B.2.2 Determination of the transmission parameters** + +To evaluate speech transmission quality of the particular connection scenarios, the parameters to describe the situation are essential. In the examples illustrated in this Recommendation, detailed transmission calculations are illustrated, followed by a summary table. + +##### **B.2.2.1 Application of the advantage factor A** + +The advantage factor A as described in 7.8 has been used for the following calculations in those cases where wireless technology is included in the reference connection. An advantage factor of $A = 5$ has been assigned to unlicensed technology (PACS, WUPE, PCI, PWT) whereas an advantage factor of $A = 10$ has been assigned to licensed technology (TDMA). It should be noted, that such an assignment of a specific value of the Advantage Factor A to a specific connection under consideration is not fixed and lies completely within the responsibility of the transmission planner. Further guidance and upper limits of the advantage factor A for typical situations can be found in 7.8. + +#### **B.2.2.2 Use of digital pads** + +For the planning examples describing the North American scenarios it has been assumed that loss or gain adjustments in PBXs or DEOs is performed by digital pads, resulting in additional 0.7 qdu, each. + +#### **B.2.3 End-to-end calculation with the E-Model** + +After determining and collecting all necessary data, the calculations with the E-Model can now be executed. In this Recommendation, the calculations are made for each of the three reference configurations separately. The configurations are illustrated in the diagrams shown prior to the pre-calculation section. + +Parameters which are standard across North America have been used and where relevant used, as default values and are being labelled as "default" where applicable. Calculations are shown only for those parameters that change. + +#### B.2.4 Reference configuration 1a (analogue set @ A, analogue set @ B) + +This configuration represents a private network-to-public network connection with the private network termination consisting of an analogue telephone set. This connection is the North American equivalent to reference configuration 1 in B.1 with an analogue set at the private network termination. + +In configuration 1a, the analogue telephone at Side A connects to digital PBX A by an ONS (ON-premises Station) port. PBX A connects to transit PBX C via an Integrated Services Trunk (IST) port. The PBX base loss is 3 dB towards the IST and 6 dB towards the ONS, in accordance with the loss plan of [40] for ONS-IST connection. This loss is varied in 1 dB steps (V) to obtain a plot of speech transmission quality versus PBX loss insertion for this connection. The digital tie trunk facility, B, uses low bit-rate encoding equipment. Transit PBX C connects the digital tie trunk (IST) to a Digital Access Line (DAL). Per the PBX loss plan in [40], the loss for this PBX connection is 0 dB in both directions. The digital access line, D, connects to local PSTN office E for connection to the public switched digital network F for termination at local digital office G. In compliance with the public network digital loss plan, office G inserts 6 dB loss in the receive (towards analogue access line of subscriber) direction. + +![Diagram of reference configuration 1a showing signal flow and loss levels between a private network (Side A) and a public network (Side B).](9e3c3a68ea23d6b0c0243f2baa1cb99f_img.jpg) + +Configuration 1a: analogue set @ A; analogue set @ B + +The diagram illustrates the signal path and loss levels for reference configuration 1a. It is divided into two main sections: Private network (Side A) and Public network (Side B), separated by a 0 dB point. + +- Side A (Private network):** + - An analogue telephone is connected to an ONS (ON-premises Station) port of PBX A. The signal level at the telephone is SLR = 8 dB. + - The ONS port has a loss of 3+V dB towards the IST and 6+V dB towards the ONS. The ERL (Echo Return Loss) at the ONS is 12 dB. + - The IST port of PBX A connects to the digital tie trunk facility, B, which contains low bit-rate encoding equipment. + - The signal level at the IST port is 0 dB. + - The PBX base loss is 3 dB towards the IST and 6 dB towards the ONS, varied in 1 dB steps (V). + - The signal level at the 0 dB point is 0 dB. +- Side B (Public network):** + - The signal flows from the 0 dB point through PBX C (transit PBX) via an IST port to a Digital Access Line (DAL). + - The loss at PBX C is 0 dB in both directions. + - The signal then flows through local PSTN office E, then through the public switched digital network F, and finally to local digital office G. + - At office G, a loss of 6 dB is inserted in the receive direction. + - The signal then connects to an analogue telephone at Side B. + - The signal level at the telephone is RLR = -3 dB. + - The signal level at the line is Line 0 dB. + - The signal level at the telephone is SLR = 11 dB. + +Additional parameters shown in the diagram: + +- RLRA = -6 dB (at Side A telephone) +- RLRB = -3 dB (at Side B telephone) +- Mean one-way delay in ms: 1.5 (A), 1.5 (B), 1.5 (C), 10 (D), 1.5 (E), 10 (F), 1.5 (G). +- Echo path (Side B) and Echo path (Side A) are indicated. +- Vary V from 0-10 dB simultaneously in 1 dB steps. +- T1211460-99 (reference number). + +Diagram of reference configuration 1a showing signal flow and loss levels between a private network (Side A) and a public network (Side B). + +(In this scenario, A is a terminating PBX, C is a transit PBX) + +Figure B.13/G.108 – Basis for calculation for reference configuration 1a + +##### B.2.4.1 Pre-calculations for configuration 1a + +##### B.2.4.1.1 Calculation of SLR, RLR and OLR + +###### Side A + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|------------------------------------|-------------------------------| +| Telephone set | SLR 8 dB | RLR -6 dB | +| PBX A | 3 + V dB | 6 + V dB | +| Sum at 0 dBr point | SLRA = 11 + V dB | RLRA = V dB | + +###### Side B + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|--------------------------------|-------------------------------| +| Telephone set | SLR 11 dB | RLR -3 dB | +| DEO G | 0 dB | 6 dB | +| DEO E | 0 dB | 0 dB | +| PBX C | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRB = 11 dB | RLRB = 3 dB | + +###### OLR + +| Listener at Side A | Listener at Side B | +|--------------------------|------------------------------| +| SLR B = 11 dB | SLR A = 11 + V dB | +| RLR A = V dB | RLR B = 3 dB | +| OLR = 11 + V dB | OLR = 14 + V dB | + +##### B.2.4.1.2 Talker Echo Loudness Rating (TELR) + +###### Analysis of TELR performed at Side A: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET A}} + \text{return loss (B)} + \text{sum of node losses} + \text{RLR}_{\text{SET A}} \\ + &= 8 + 14 + (3 + V + 0 + 6 + 0 + 0 + 6 + V) + (-6) \\ + &= 31 + 2 V \text{ dB} + \end{aligned}$$ + +###### Analysis of TELR performed at Side B: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET B}} + \text{return loss (A)} + \text{sum of node losses} + \text{RLR}_{\text{SET B}} \\ + &= 11 + 12 + (0 + 0 + 6 + V + 3 + V + 0 + 6) + (-3) \\ + &= 35 + 2 V \text{ dB} + \end{aligned}$$ + +##### B.2.4.1.3 Weighted Echo Path Loss (WEPL) + +$$\begin{aligned} + \text{WEPL} &= \text{return loss (A)} + \text{return loss (B)} + \text{sum of node losses} \\ + &= 12 + 14 + (3 + V + 0 + 6 + 0 + 0 + 6 + V) \\ + &= 41 + 2 V \text{ dB} + \end{aligned}$$ + +##### B.2.4.1.4 Delay values T, Ta and Tr + +$$\begin{aligned} T(\text{ms}) &= \text{sum of PBXs delay} + \text{low bit-rate equipment delay} + \text{digital end office (C) delay} + \\ &\quad \text{network delay} + \text{digital end office (G) delay} \\ &= 1.5 + 1.5 + 1.5 + 10 + 1.5 \\ &= 16 \end{aligned}$$ + +$$T_a = T$$ + +$$T_r = 2 \times T$$ + +##### B.2.4.1.5 Number of quantization distortion units + +This parameter represents the impairments due to quantization distortion. It is entered as the number of quantization distortion units. Note that a value of 1 is used for the A/D-D/A conversion. Digital loss pads have additional qdu value of 0.7. In this scenario, there are altogether 1 pair of A/D-D/A conversion and one digital pad if Side A is the listener and two digital pads if Side B is the listener. + +$$\begin{aligned} \text{Therefore, } qdu_A &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 1 \times 0.7 \\ &= 1.7 \\ qdu_B &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 2 \times 0.7 \\ &= 2.4 \end{aligned}$$ + +where $n$ = number of A/D-D/A conversion pairs + +$m$ = number of digital pads + +##### B.2.4.1.6 Equipment impairment factor + +In the above example, a low-bit rate codec is used in Section B within the private network. Typically, ADPCM 32 kbit/s is used. This codec does have a mild degradation to voice, and according to Table 2, the value of the equipment impairment factor $I_e$ is 7. + +#### B.2.4.2 Input parameters summary tables + +The input parameters for configuration 1a are summarized in Tables B.2a and B.2b; all other parameters remain at their default values according to Table 6. + +**Table B.2a/G.108 – E-Model input parameters for configuration 1a +as perceived at side A** + +| Input Parameters | Values | Unit | +|---------------------------------------|-----------|------| +| Send Loudness Rating ( $SLR_B$ ) | 11 | dB | +| Receive Loudness Rating ( $RLR_A$ ) | V | dB | +| Talker Echo Loudness Rating | $31 + 2V$ | dB | +| Weighted Echo Path Loss | $41 + 2V$ | dB | +| Equipment impairment factor ( $I_e$ ) | 7 | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 32 | ms | +| Mean one-way delay | 16 | ms | +| Absolute delay | 16 | ms | + +**Table B.2b/G.108 – E-Model input parameters for configuration 1a as perceived at side B** + +| Input Parameters | Values | Unit | +|-----------------------------------------------|---------|------| +| Send Loudness Rating (SLR A ) | 11 + V | dB | +| Receive Loudness Rating (RLR B ) | 3 | dB | +| Talker Echo Loudness Rating | 35 + 2V | dB | +| Weighted Echo Path Loss | 41 + 2V | dB | +| Equipment impairment factor (I e ) | 7 | | +| Quantization distortion unit | 2.4 | | +| Round trip delay | 32 | ms | +| Mean one-way delay | 16 | ms | +| Absolute delay | 16 | ms | + +#### **B.2.4.3 Results** + +![Graph showing E-Model Rating R vs Incremental PBX Loss. The curve peaks at T = 16 ms.](c9829c80e5f6e9384df5f75e24da4c25_img.jpg) + +Config 1a: Side A +analogue set @ A & analogue set @ B + +The graph plots the E-Model Rating R (y-axis, 64 to 86) against Incremental PBX Loss (x-axis, 0 to 10 dB). A single curve is shown, representing the relationship between the two variables. The curve starts at approximately 70 at 0 dB loss, rises to a peak of about 74.5 at 4.5 dB loss, and then declines to about 70 at 10 dB loss. A label 'T = 16 ms' is placed near the peak of the curve. The x-axis is labeled 'Incremental PBX Loss' and the y-axis is labeled 'E-Model Rating R'. A small code 'T1211470-99' is visible in the bottom right corner of the graph area. + +| Incremental PBX Loss (dB) | E-Model Rating R | +|---------------------------|------------------| +| 0 | 70 | +| 1 | 72 | +| 2 | 73.5 | +| 3 | 74.2 | +| 4 | 74.5 | +| 5 | 74.2 | +| 6 | 73.5 | +| 7 | 72.5 | +| 8 | 71.5 | +| 9 | 70.5 | +| 10 | 70 | + +Graph showing E-Model Rating R vs Incremental PBX Loss. The curve peaks at T = 16 ms. + +**Figure B.13a/G.108 – Analogue set @ A & analogue set @ B as perceived @ side A** + +As Figure B.13a shows, optimal speech transmission quality for the listener at side A can be achieved when incremental PBX loss is in the range of 3 to 5 dB. + +![Figure B.13b/G.108 graph showing E-Model Rating R vs Incremental PBX Loss for Config 1a: Side B. The graph shows a curve starting at approximately 72 at 0 dB loss, peaking at about 73 at 2 dB loss, and then decreasing to about 65 at 10 dB loss. A label 'T = 16 ms' is present near the curve at 5 dB loss. The y-axis is labeled 'E-Model Rating R' and ranges from 64 to 86. The x-axis is labeled 'Incremental PBX Loss' and ranges from 0 to 10 dB. A small code 'T1211480-99' is in the bottom right corner.](0735f69ccc1c6ec7d0f9354d8d0e7c68_img.jpg) + +Config 1a: Side B +analogue set @ A & analogue set @ B + +| Incremental PBX Loss (dB) | E-Model Rating R | +|---------------------------|------------------| +| 0 | 72 | +| 1 | 73 | +| 2 | 73 | +| 3 | 72 | +| 4 | 71 | +| 5 | 70 | +| 6 | 68 | +| 7 | 66 | +| 8 | 64 | +| 9 | 63 | +| 10 | 62 | + +Figure B.13b/G.108 graph showing E-Model Rating R vs Incremental PBX Loss for Config 1a: Side B. The graph shows a curve starting at approximately 72 at 0 dB loss, peaking at about 73 at 2 dB loss, and then decreasing to about 65 at 10 dB loss. A label 'T = 16 ms' is present near the curve at 5 dB loss. The y-axis is labeled 'E-Model Rating R' and ranges from 64 to 86. The x-axis is labeled 'Incremental PBX Loss' and ranges from 0 to 10 dB. A small code 'T1211480-99' is in the bottom right corner. + +**Figure B.13b/G.108 – Analogue set @ A & analogue set @ B as perceived @ side B** + +Figure B.13b shows optimal speech transmission quality can be achieved for the listener at side B when PBX incremental loss is in the range of 1 to 3 dB. The absolute optimum performance is somewhat less than for side A; this is due to the somewhat greater (14 dB versus 11 dB) acoustic end-to-end loss when B is the listener. However, the optimum occurs for a lower amount of incremental PBX loss, since the TELR is somewhat greater for side B. + +#### **B.2.5 Reference configuration 1b (digital set @ A, analogue set @ B)** + +This configuration represents a private network-to-public network connection with the private network termination consisting of a digital telephone set. This connection is the North American equivalent to reference configuration 1 in Section D with a digital set at the private network termination. + +In configuration 1b, the digital telephone at side A connects to digital PBX A by an ICS (ISDN Compatible Station) port. PBX A connects to transit PBX C via an Integrated Services Trunk (IST) port. The PBX base loss is 0 dB in each direction, in accordance with the loss plan of [40] for ONS-IST connection. This loss is varied in 1 dB steps (V) to obtain a plot of speech transmission quality versus PBX loss insertion for this connection. The digital tie trunk facility, B, uses low bit-rate encoding equipment. Transit PBX C connects the digital tie trunk (IST) to a Digital Access Line (DAL). Per the PBX loss plan in [40], the loss for this PBX connection is 0 dB in both directions. The digital access line, D, connects to local PSTN office E for connection to the public switched digital network F for termination at local digital office G. In compliance with the public network digital loss plan, office G inserts 6 dB loss in the receive (towards analogue access line of subscriber) direction. + +Configuration 1b: digital set @ A; analogue set @ B + +![Diagram of Configuration 1b showing a digital telephone at Side A connected through a private network (PBX A, Low bit-rate equipment, PBX C) to a public network (DEO G, DEO E, PBX C) and finally to an analogue telephone at Side B. The diagram includes various gain and loss parameters like SLR, RLR, ERL, and mean one-way delay.](207817524fe964425718e1723d5b7d9e_img.jpg) + +The diagram illustrates the signal path for Configuration 1b. On Side A (Private network), a Digital telephone is connected to PBX A. The signal flows from the telephone through PBX A (0+V dB), then through Low bit-rate equipment (IST, DAL), then through PBX C (0 dB), and finally through the Public network (DEO G, DEO E, PBX C) to an Analogue telephone on Side B. The diagram includes various gain and loss parameters: SLRA = 8 dB, RLRA = 2 dB, ERL = 45 dB, 0+V dB, 0 dB, 6 dB, ERL = 14 dB, RLRB = -3 dB, SLRB = 11 dB. The mean one-way delay is indicated as 1.5 ms for each segment. The echo paths are also shown: Echo path (Side B) and Echo path (Side A). + +Diagram of Configuration 1b showing a digital telephone at Side A connected through a private network (PBX A, Low bit-rate equipment, PBX C) to a public network (DEO G, DEO E, PBX C) and finally to an analogue telephone at Side B. The diagram includes various gain and loss parameters like SLR, RLR, ERL, and mean one-way delay. + +(In this scenario, A is a terminating PBX, C is a transit PBX) + +Figure B.14/G.108 – Basis for calculation of reference configuration 1b + +#### B.2.5.1 Pre-calculations for configuration 1b + +##### B.2.5.1.1 Calculation of SLR, RLR and OLR + +###### Side A + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|-----------------------------------|-----------------------------------| +| Telephone set | SLR 8 dB | RLR 2 dB | +| PBX A | 0 + V dB | 0 + V dB | +| Sum at 0 dBr point | SLRA = 8 + V dB | RLRA = 2 + V dB | + +###### Side B + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|--------------------------------|-------------------------------| +| Telephone set | SLR 11 dB | RLR -3dB | +| DEO G | 0 dB | 6 dB | +| DEO E | 0 dB | 0 dB | +| PBX C | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRB = 11 dB | RLRB = 3 dB | + +###### OLR + +| Listener at Side A | Listener at Side B | +|-----------------------------|-----------------------------| +| SLR B = 11 dB | SLR A = 8 + V dB | +| RLR A = 2 + V dB | RLR B = 3 dB | +| OLR = 13 + V dB | OLR = 11 + V dB | + +##### **B.2.5.1.2 Talker Echo Loudness Rating (TELR)** + +###### **Analysis of TELR performed at Side A:** + +$$\begin{aligned}\text{TELR} &= \text{SLR}_{\text{SET A}} + \text{return loss (B)} + \text{sum of node losses} + \text{RLR}_{\text{SET A}} \\ &= 8 + 14 + (0 + V + 0 + 6 + 0 + 0 + 0 + V) + 2 \\ &= 30 + 2 V \text{ dB}\end{aligned}$$ + +###### **Analysis of TELR performed at Side B:** + +$$\begin{aligned}\text{TELR} &= \text{SLR}_{\text{SET B}} + \text{return loss (A)} + \text{sum of node losses} + \text{RLR}_{\text{SET B}} \\ &= 11 + 45 + (0 + 0 + 0 + V + 0 + V + 0 + 6) + (-3) \\ &= 59 + 2 V \text{ dB}\end{aligned}$$ + +##### **B.2.5.1.3 Weighted Echo Path Loss (WEPL)** + +$$\begin{aligned}\text{WEPL} &= \text{return loss (A)} + \text{return loss (B)} + \text{sum of node losses} \\ &= 45 + 14 + (0 + V + 0 + 6 + 0 + 0 + 0 + V) \\ &= 65 + 2 V \text{ dB}\end{aligned}$$ + +##### **B.2.5.1.4 Delay values T, Ta and Tr** + +$$\begin{aligned}T(\text{ms}) &= \text{sum of PBXs delay} + \text{low bit-rate equipment delay} + \text{digital end office(C) delay} + \text{network delay} + \text{digital end office(G) delay} \\ &= 1.5 + 1.5 + 1.5 + 10 + 1.5 \\ &= 16\end{aligned}$$ + +$$T_a = T$$ + +$$T_r = 2 \times T$$ + +##### **B.2.5.1.5 Number of quantization distortion units** + +This parameter represents the impairments due to quantization distortion. It is entered as the number of quantization distortion units. Note that a value of 1 is used for the A/D-D/A conversion. Digital loss pads have additional qdu value of 0.7. In this scenario, there are altogether one pair of A/D-D/A conversion and one digital loss pad if side A is the listener and two digital pads if side B is the listener. + +$$\begin{aligned}\text{Therefore, } \text{qdu}_A &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 1 \times 0.7 \\ &= 1.7 \\ \text{qdu}_B &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 2 \times 0.7 \\ &= 2.4\end{aligned}$$ + +where $n$ = number of A/D-D/A conversion pairs + $m$ = number of digital pads + +##### B.2.5.1.6 Equipment impairment factor + +In the above example, a low-bit rate codec is used in Section B within the private network. Typically, ADPCM 32 kbit/s is used. This codec does have a mild degradation to voice, and according to Table 2, the value of the equipment impairment factor ( $I_e$ ) is 7. + +#### B.2.5.2 Input parameters summary tables + +The input parameters for configuration 1b are summarized in Tables B.3a and B.3b; all other parameter remain at their default values according to Table 6. + +**Table B.3a/G.108 – E-Model input parameters for configuration 1b as perceived at side A** + +| Input Parameters | Values | Unit | +|---------------------------------------|-----------|------| +| Send Loudness Rating ( $SLR_B$ ) | 11 | dB | +| Receive Loudness Rating ( $RLR_A$ ) | $2 + V$ | dB | +| Talker Echo Loudness Rating | $30 + 2V$ | dB | +| Weighted Echo Path Loss | $65 + 2V$ | dB | +| Equipment impairment factor ( $I_e$ ) | 7 | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 32 | ms | +| Mean one-way delay | 16 | ms | +| Absolute delay | 16 | ms | + +**Table B.3b/G.108 – E-Model input parameters for configuration 1b as perceived at side B** + +| Input parameters | Values | Unit | +|---------------------------------------|-----------|------| +| Send Loudness Rating ( $SLR_A$ ) | $8 + V$ | dB | +| Receive Loudness Rating ( $RLR_B$ ) | 3 | dB | +| Talker Echo Loudness Rating | $59 + 2V$ | dB | +| Weighted Echo Path Loss | $65 + 2V$ | dB | +| Equipment impairment factor ( $I_e$ ) | 7 | | +| Quantization distortion unit | 2.4 | | +| Round trip delay | 32 | ms | +| Mean one-way delay | 16 | ms | +| Absolute delay | 16 | ms | + +#### B.2.5.3 Results + +![Graph showing E-Model Rating R vs Incremental PBX Loss for Side A. The curve peaks at approximately 71.5 dB with a rating of about 71.5. The curve is labeled T = 16 ms. The x-axis ranges from 0 to 10 dB, and the y-axis ranges from 64 to 86.](1467d34183acbcea92a61155e0d230ec_img.jpg) + +Config 1b: Side A +digital set @ A & analogue set @ B + +E-Model Rating R + +T = 16 ms + +Incremental PBX Loss + +T1211500-99 + +| Incremental PBX Loss (dB) | E-Model Rating R | +|---------------------------|------------------| +| 0 | 66 | +| 1 | 68 | +| 2 | 70 | +| 3 | 71 | +| 4 | 71.5 | +| 5 | 71.5 | +| 6 | 71 | +| 7 | 70 | +| 8 | 68 | +| 9 | 67 | +| 10 | 66 | + +Graph showing E-Model Rating R vs Incremental PBX Loss for Side A. The curve peaks at approximately 71.5 dB with a rating of about 71.5. The curve is labeled T = 16 ms. The x-axis ranges from 0 to 10 dB, and the y-axis ranges from 64 to 86. + +Figure B.14a/G.108 – Digital set @ A & analogue set @ B as perceived @ side A + +![Graph showing E-Model Rating R vs Incremental PBX Loss for Side B. The curve starts at approximately 85 at 0 dB and decreases linearly to about 71 at 10 dB. The curve is labeled T = 16 ms. The x-axis ranges from 0 to 10 dB, and the y-axis ranges from 64 to 86.](21998d5161d55a19df06b0ea8d3b4e59_img.jpg) + +Config 1b: Side B +digital set @ A & analogue set @ B + +E-Model Rating R + +T = 16 ms + +Incremental PBX Loss + +T1211510-99 + +| Incremental PBX Loss (dB) | E-Model Rating R | +|---------------------------|------------------| +| 0 | 85 | +| 1 | 83 | +| 2 | 81 | +| 3 | 79 | +| 4 | 77 | +| 5 | 75 | +| 6 | 73 | +| 7 | 71 | +| 8 | 69 | +| 9 | 67 | +| 10 | 65 | + +Graph showing E-Model Rating R vs Incremental PBX Loss for Side B. The curve starts at approximately 85 at 0 dB and decreases linearly to about 71 at 10 dB. The curve is labeled T = 16 ms. The x-axis ranges from 0 to 10 dB, and the y-axis ranges from 64 to 86. + +Figure B.14b/G.108 – Digital set @ A & analogue set @ B as perceived @ side B + +Figures B.14a and B.14b illustrate optimal speech transmission quality points at respective incremental losses at the PBXs. For side B, the optimal speech transmission quality is located when there is no further loss in the PBX since the high echo return loss (ERL) value of 45 dB provides sufficient echo control to minimize echo effects. + +On the other hand, when listener is at side A, where the opposing side (B) has an ERL of only 14 dB, a value in the range of 4-4.5 dB indicates the best possible speech transmission quality to be obtained. + +#### B.2.6 Reference configuration 2 (portable connection scenario) + +This configuration represents a private network-to-public network connection with the private network termination consisting of a portable telephone set. This connection is the North American equivalent to reference configuration 2 in B.1. + +In configuration 2, the portable (wireless set) at side A connects to digital PBX A by an ICS (ISDN Compatible Station) port. PBX A connects to transit PBX C via a Integrated Services Trunk (IST) port. The PBX loss is 0 dB in each direction, in accordance with the loss plan of [40] for ONS-IST connection. The digital tie trunk facility, B, uses low bit-rate encoding equipment. Transit PBX C connects the digital tie trunk (IST) to a Digital Access Line (DAL). Per the PBX loss plan in [40], the loss for this PBX connection is 0 dB in both direction. The digital access line, D, connects to local PSTN office E for connection to the public switched digital network F for termination at local digital office G. In compliance with the public network digital loss plan, office G inserts 6 dB loss in the receive (towards analogue access line of subscriber) direction. + +Configuration 2: portable set @ A; analogue set @ B + +![Diagram of Reference configuration 2 showing signal flow from a portable set at Side A through various network components (PBX A, transit PBX C, PSTN office E, digital office G) to an analogue telephone at Side B. It includes labels for signal levels (SLR, RLR, ERL), losses (0 dB, 6 dB), and processing delays (1.5 ms, 10 ms).](a3d6b1f562612dbd5a5d7c4ce91999d1_img.jpg) + +The diagram illustrates the signal path for Reference configuration 2. It is divided into a 'Private network' (Side A) and a 'Public network' (Side B). At Side A, a 'portable' device connects to PBX A via an ICS port. The signal levels are SLRA = 8 dB and RLR = 2 dB. PBX A has an ERL of 45 dB and 0 dB loss. The signal then travels through a 'Low bit-rate equipment' (IST) to PBX C. PBX C also has 0 dB loss. The signal then travels through a Digital Access Line (DAL) to PSTN office E. The signal levels at the IST/DAL interface are IST and DAL. The signal then travels through PSTN office E to digital office G. The signal levels at the DAL interface are 0 dB. The signal then travels through digital office G, which has a 6 dB loss in the receive direction. The signal levels at the digital office G interface are ERL = 14 dB and 0 dB. The signal then travels through a 'Line 0 dB' to an 'Analogue telephone' at Side B. The signal levels at the analogue telephone are RLR = -3 dB and SLR = 11 dB. The diagram also shows 'Echo path (Side B)' and 'Echo path (Side A)'. Below the diagram, a table provides average processing delays for different technologies. + +| Technology | Average processing delay | +|-----------------------------------|--------------------------------| +| Unlicensed (PACS, WUPE, PCI, PWT) | 7 ms (ranges from 4-10 ms) | +| Licensed TDMA | 100 ms (ranges from 70-100 ms) | + +Diagram of Reference configuration 2 showing signal flow from a portable set at Side A through various network components (PBX A, transit PBX C, PSTN office E, digital office G) to an analogue telephone at Side B. It includes labels for signal levels (SLR, RLR, ERL), losses (0 dB, 6 dB), and processing delays (1.5 ms, 10 ms). + +Figure B.15/G.108 – Basis for calculation of reference configuration 2 + +#### B.2.6.1 Pre-calculations for configuration 2 + +##### B.2.6.1.1 Calculation of SLR, RLR and OLR + +###### Side A + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|-------------------------------|-------------------------------| +| Telephone set | SLR 8 dB | RLR 2 dB | +| PBX A | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRA = 8 dB | RLRA = 2 dB | + +###### Side B + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|--------------------------------|-------------------------------| +| Telephone set | SLR 11 dB | RLR -3dB | +| DEO G | 0 dB | 6 dB | +| DEO E | 0 dB | 0 dB | +| PBX C | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRB = 11 dB | RLRB = 3 dB | + +###### OLR + +| Listener at Side A | Listener at Side B | +|--------------------------|-------------------------| +| SLR B = 11 dB | SLR A = 8 dB | +| RLR A = 2 dB | RLR B = 3 dB | +| OLR = 13 dB | OLR = 11 dB | + +##### B.2.6.1.2 Talker Echo Loudness Rating (TELR) + +###### Analysis of TELR performed at Side A: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET A}} + \text{return loss (B)} + \text{sum of node losses} + \text{RLR}_{\text{SET A}} \\ + &= 8 + 14 + (0 + 0 + 6 + 0 + 0 + 0) + 2 \\ + &= 30 \text{ dB} + \end{aligned}$$ + +###### Analysis of TELR performed at Side B: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET B}} + \text{return loss (A)} + \text{sum of node losses} + \text{RLR}_{\text{SET B}} \\ + &= 11 + 45 + (0 + 0 + 0 + 0 + 0 + 6) + (-3) \\ + &= 59 \text{ dB} + \end{aligned}$$ + +##### B.2.6.1.3 Weighted Echo Path Loss (WEPL) + +$$\begin{aligned} + \text{WEPL} &= \text{return loss (A)} + \text{return loss (B)} + \text{sum of node losses} \\ + &= 45 + 14 + (0 + 0 + 6 + 0 + 0 + 0) \\ + &= 65 \text{ dB} + \end{aligned}$$ + +##### **B.2.6.1.4 Delay values T, Ta and Tr** + +$$\begin{aligned} T(\text{ms}) &= \text{Access delay of wireless technology} + \text{PBX delay} + \text{low bit-rate equipment delay} + \\ &\quad \text{digital end office delay} + \text{network delay} + \text{digital end office delay} \\ &= 7 \text{ (unlicensed)} \text{ or } 100 \text{ (licensed)} + 1.5 + 1.5 + 1.5 + 10 + 1.5 \\ &= 23 \text{ or } 116 \end{aligned}$$ + +$$T_a = T$$ + +$$T_r = 2 \times T$$ + +##### **B.2.6.1.5 Number of quantization distortion units** + +This parameter represents the impairments due to quantization distortion. It is entered as the number of quantization distortion units. Note that a value of 1 is used for the A/D-D/A conversion. Digital loss pads have additional qdu value of 0.7. In this scenario, there are altogether 1 pair of A/D-D/A conversion and zero digital loss pads if side A is the listener and one digital pad if side B is the listener. + +$$\begin{aligned} \text{Therefore, } qdu_A &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 0 \times 0.7 \\ &= 1.0 \\ qdu_B &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 1 \times 0.7 \\ &= 1.7 \end{aligned}$$ + +where $n$ = number of A/D-D/A conversion pairs + +$m$ = number of digital pads + +##### **B.2.6.1.6 Equipment impairment factor** + +The codec used for wireless technology does have an impact on speech transmission quality. For the two types of technology analysed, values in Table 2a were used. The total equipment impairment factor ( $I_e$ ) is the sum of all the equipment impairment factors involved: + +$$\begin{aligned} I_e &= I_e \text{ value for codec used in wireless technology} + I_e \text{ value for network LBR equipment} \\ &= 7 \text{ (unlicensed)} \text{ or } 10 \text{ (licensed)} + 0 \text{ (0 LBR)} \text{ or } 7 \text{ (1 LBR)} \\ &= 7 \text{ or } 14 \text{ (unlicensed)} \qquad \qquad \qquad \text{or} \\ &= 10 \text{ or } 17 \text{ (licensed)} \end{aligned}$$ + +#### **B.2.6.2 Input parameters summary tables** + +The input parameters for Configuration 2 are summarized in Tables B.4a and B.4b; all other parameters remain at their default values according to Table 6. + +**Table B.4a/G.108 – E-Model Input Parameters for Configuration 2 +as perceived at side A** + +| Input Parameters | Values | Unit | +|-----------------------------------------------|----------------------------------------------|-------------| +| Send Loudness Rating (SLR B ) | 11 | dB | +| Receive Loudness Rating (RLR A ) | 2 | dB | +| Talker Echo Loudness Rating | 30 | dB | +| Weighted Echo Path Loss | 65 | dB | +| Equipment impairment factor (I e ) | 7 or 14 (unlicensed),
10 or 17 (licensed) | | +| Advantage factor (A) | 5 (unlicensed),
10 (licensed) | | +| Quantization distortion unit | 1 | | +| Round trip delay | 46 (unlicensed)
232 (licensed) | ms | +| Mean one-way delay | 23 (unlicensed)
116 (licensed) | ms | +| Absolute delay | 23 (unlicensed)
116 (licensed) | ms | + +**Table B.4b/G.108 – E-Model input parameters for configuration 2 +as perceived at side B** + +| Input parameters | Values | Unit | +|-----------------------------------------------|----------------------------------------------|-------------| +| Send Loudness Rating (SLR A ) | 8 | dB | +| Receive Loudness Rating (RLR B ) | 3 | dB | +| Talker Echo Loudness Rating | 59 | dB | +| Weighted Echo Path Loss | 65 | dB | +| Equipment impairment factor (I e ) | 7 or 14 (unlicensed),
10 or 17 (licensed) | | +| Advantage factor (A) | 5 (unlicensed),
10 (licensed) | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 46 (unlicensed)
232 (licensed) | ms | +| Mean one-way delay | 23 (unlicensed)
116 (licensed) | ms | +| Absolute delay | 23 (unlicensed)
116 (licensed) | ms | + +#### B.2.6.3 Results + +###### B.2.6.3.1 Unlicensed: Wireless processing delay: 7 ms average (WUPE, PCI, PWT) + +![Bar chart showing E-Model Rating R for unlicensed wireless processing delay (7 ms avg) at Side A and Side B, comparing 'With one LBR' and 'Without LBR'.](111c2953ce033bb5d26aaa0b071e8a7f_img.jpg) + +Unlicensed: Wireless processing delay: 7 ms avg + +The chart displays the E-Model Rating R on the y-axis (0 to 100) for two listener locations, Side A and Side B, on the x-axis. For each side, two bars are shown: a dark grey bar for 'With one LBR' and a white bar for 'Without LBR'. The data values are: Side A (With one LBR: 56.8, Without LBR: 63.8) and Side B (With one LBR: 82.5, Without LBR: 89.5). The chart is labeled T1211530-99. + +| Listener location | With one LBR | Without LBR | +|-------------------|--------------|-------------| +| Side A | 56.8 | 63.8 | +| Side B | 82.5 | 89.5 | + +Bar chart showing E-Model Rating R for unlicensed wireless processing delay (7 ms avg) at Side A and Side B, comparing 'With one LBR' and 'Without LBR'. + +Figure B.15a/G.108 – Unlicensed: Wireless processing delay: 7 ms avg + +Figure B.15a shows speech transmission quality performance when listener is at side A and side B respectively. The two bars denote the cases when there is a set of low bit-rate equipment and when there is none. It can be observed that speech transmission quality perceived at side B is better than when perceived at side A. The reason for this discrepancy is that the echo return loss value at side A is much larger than that of side B (45 dB versus 14 dB). With a larger ERL, echo cancellation is more effective and, thereby, improves the speech transmission quality. + +It can also be observed that the low bit-rate equipment degrades speech transmission quality which can make a difference, especially when echo cancellation is not handled effectively (larger differences at side A compared with side B). + +##### B.2.6.3.2 Licensed: Wireless processing delay: 100 ms average (TDMA) + +![Bar chart showing E-Model Rating R for licensed wireless processing delay (100 ms avg) at Side A and Side B, comparing 'With one LBR' and 'Without LBR'.](233592bfd37a67f8c04f282d2a0c46d6_img.jpg) + +Licensed: Wireless processing delay: 100 ms avg + +The chart displays the E-Model Rating R on the y-axis (0 to 100) for two listener locations, Side A and Side B, on the x-axis. For each side, two bars are shown: a dark grey bar for 'With one LBR' and a white bar for 'Without LBR'. The data values are: Side A (With one LBR: 21.0, Without LBR: 28.0) and Side B (With one LBR: 80.0, Without LBR: 87.0). The chart is labeled T1211540-99. + +| Listener location | With one LBR | Without LBR | +|-------------------|--------------|-------------| +| Side A | 21.0 | 28.0 | +| Side B | 80.0 | 87.0 | + +Bar chart showing E-Model Rating R for licensed wireless processing delay (100 ms avg) at Side A and Side B, comparing 'With one LBR' and 'Without LBR'. + +Figure B.15b/G.108 – Licensed: Wireless processing delay: 100 ms avg + +In Figure B.15b the same observation is shown for licensed technology. The only difference is that the absolute number in terms of performance is much lower than for the unlicensed wireless technology. The reason is that licensed wireless technology has much longer delay (100 ms versus 7 ms average), and the equipment impairment factor of the associated low bit rate codec is larger. + +#### B.2.7 Reference configuration 3a (analogue set @ B) + +This configuration represents a private network connection with one termination consisting of a portable telephone set and the other termination an analogue telephone set. This connection is the North American equivalent to reference configuration 3 in B.1 with an analogue telephone set at side B. + +In configuration 3a, the portable (wireless set) at side A connects to digital PBX B by an ICS (ISDN Compatible Station) port. PBX A connects to transit PBX A via a Integrated Services Trunk (IST) port. The PBX loss is 0 dB in each direction, in accordance with the loss plan of [40] for ONS-IST connection. The digital tie trunk facility uses. Transit PBX A connects the digital tie trunk (IST) to another digital tie trunk (IST). Per the PBX loss plan in [40], the loss for this PBX connection is 0 dB in both directions. This digital tie trunk connects to terminating digital PBX D. As shown, both tie trunk facilities use low bit-rate encoding equipment; the analysis for this connection is made for this case, as well as for cases where only one or where neither tie trunk uses such equipment. PBX D connects to an analogue telephone via an ONS port with the losses as described in configuration 1a. + +Configuration 3a: portable set @ A; analogue set @ B + +![Diagram of reference configuration 3a showing signal flow from a portable set at Side A to an analogue telephone at Side B through various PBXs and low bit-rate equipment. It includes loss values (SLR, RLR, ERL) and processing delays for different technologies.](868ee7df1ec851f132ccf8c390de76a8_img.jpg) + +The diagram illustrates the signal path and loss components for reference configuration 3a. It is divided into Side A (left) and Side B (right), separated by a '0 dB point'. + +- Side A:** A portable telephone (RLR = 2 dB) connects to PBX B via an ICS port. The signal passes through the ICS (SLRA = 8 dB) and then through the PBX B (0 dB loss, ERL = 45 dB). +- Transit:** From PBX B, the signal goes through an IST port, then through 'Low bit-rate equipment' (1.5 ms delay), then through another PBX A (0 dB loss, ERL = 12 dB), then through another 'Low bit-rate equipment' (1.5 ms delay), and finally through PBX D (IST port, 0 dB loss, ERL = 6 dB). +- Side B:** From PBX D, the signal goes through an ONS port (SLRB = 8 dB) to an analogue telephone (RLR = -6 dB, Ext. 0 dB). +- Echo Paths:** Two echo paths are shown: 'Echo path (Side B)' and 'Echo path (Side A)'. +- Processing Delays:** A table below the diagram provides average processing delays for different technologies: + + +| Technology | Average processing delay | +|-----------------------------------|--------------------------------| +| Unlicensed (PACS, WUPE, PCI, PWT) | 7 ms (ranges from 4-10 ms) | +| Licensed TDMA | 100 ms (ranges from 70-100 ms) | + +Diagram of reference configuration 3a showing signal flow from a portable set at Side A to an analogue telephone at Side B through various PBXs and low bit-rate equipment. It includes loss values (SLR, RLR, ERL) and processing delays for different technologies. + +Figure B.16/G.108 – Basis for calculation of reference configuration 3a + +#### B.2.7.1 Pre-calculations for configuration 3a + +##### B.2.7.1.1 Calculation of SLR, RLR and OLR + +###### Side A + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|-------------------------------|-------------------------------| +| Telephone set | SLR 8 dB | RLR 2 dB | +| PBX B | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRA = 8 dB | RLRA = 2 dB | + +###### Side B + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|--------------------------------|-------------------------------| +| Telephone set | SLR 8 dB | RLR -6 dB | +| PBX D | 3 dB | 6 dB | +| PBX A | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRB = 11 dB | RLRB = 0 dB | + +###### OLR + +| Listener at Side A | Listener at Side B | +|--------------------------|-------------------------| +| SLR B = 11 dB | SLR A = 8 dB | +| RLR A = 2 dB | RLR B = 0 dB | +| OLR = 13 dB | OLR = 8 dB | + +##### B.2.7.1.2 Talker Echo Loudness Rating (TELR) + +###### Analysis of TELR performed at Side A: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET A}} + \text{return loss (B)} + \text{sum of node losses} + \text{RLR}_{\text{SET A}} \\ + &= 8 + 12 + (0 + 0 + 6 + 3 + 0 + 0) + (2) \\ + &= 31 \text{ dB} + \end{aligned}$$ + +###### Analysis of TELR performed at Side B: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET B}} + \text{return loss (A)} + \text{sum of node losses} + \text{RLR}_{\text{SET B}} \\ + &= 8 + 45 + (3 + 0 + 0 + 0 + 0 + 0 + 6) + (-6) \\ + &= 56 \text{ dB} + \end{aligned}$$ + +##### B.2.7.1.3 Weighted Echo Path Loss (WEPL) + +$$\begin{aligned} + \text{WEPL} &= \text{return loss (A)} + \text{return loss (B)} + \text{sum of node losses} \\ + &= 45 + 12 + (0 + 0 + 6 + 3 + 0 + 0) \\ + &= 66 \text{ dB} + \end{aligned}$$ + +##### **B.2.7.1.4 Delay values T, Ta and Tr** + +$$\begin{aligned} T(\text{ms}) &= \text{Access delay of wireless technology} + \sum \text{PBX delay/end office delay} + \sum \text{low bit-rate equipment delay} \\ &= 7 \text{ (unlicensed) or } 100 \text{ (licensed)} + 3 \times 1 + 2 \times 1.5 \\ &= 13 \text{ or } 106 \end{aligned}$$ + +$$T_a = T$$ + +$$T_r = 2 \times T$$ + +##### **B.2.7.1.5 Number of quantization distortion units** + +This parameter represents the impairments due to quantization distortion. It is entered as the number of quantization distortion units. Note that a value of 1 is used for the A/D-D/A conversion. Digital loss pads have additional qdu value of 0.7. In this scenario, there are altogether 1 pair of A/D-D/A conversion and one digital loss pad for either side analysis. + +$$\begin{aligned} \text{Therefore, } qdu &= n \times 1 + m \times 0.7 \\ &= 1 \times 1 + 1 \times 0.7 \\ &= 1.7 \end{aligned}$$ + +where $n$ = number of A/D-D/A conversion pairs + +$m$ = number of digital pads + +##### **B.2.7.1.6 Equipment Impairment Factor** + +The codec used for wireless technology does have an impact on speech transmission quality. For the two types of technology analysed, values in Table 2a were used. The total equipment impairment factor ( $I_e$ ) is the sum of all the equipment impairment factors involved: + +$$\begin{aligned} I_e &= I_e \text{ value for codec used in wireless technology} + I_e \text{ value for network LBR equipment} \\ &= 7 \text{ (unlicensed) or } 10 \text{ (licensed)} + 0 \text{ (0 LBR) or } 7 \text{ (1 LBR) or } 14 \text{ (2 LBR)} \\ &= 7 \text{ or } 14 \text{ or } 21 \text{ (unlicensed)} \qquad \qquad \qquad \text{or} \\ &= 10 \text{ or } 17 \text{ or } 24 \text{ (licensed)} \end{aligned}$$ + +#### **B.2.7.2 Input parameters summary tables** + +The input parameters for configuration 3a (analogue set @ B) are summarized in Tables B.5a and B.5b; all other parameter remain at their default values according to Table 6. + +**Table B.5a/G.108 – E-Model input parameters for configuration 3a +(analogue set @ B) as perceived at side A** + +| Input parameters | Values | Unit | +|-----------------------------------------------|----------------------------------------------------------|------| +| Send Loudness Rating (SLR B ) | 11 | dB | +| Receive Loudness Rating (RLR A ) | 2 | dB | +| Talker Echo Loudness Rating | 31 | dB | +| Weighted Echo Path Loss | 66 | dB | +| Equipment impairment factor (I e ) | 7 or 14 or 21 (unlicensed),
10 or 17 or 24 (licensed) | | +| Advantage factor (A) | 5 (unlicensed)
10 (licensed) | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 26 (unlicensed)
212 (licensed) | ms | +| Mean one-way delay | 13 (unlicensed)
106 (licensed) | ms | +| Absolute delay | 13 (unlicensed)
106 (licensed) | ms | + +**Table B.5b/G.108 – E-Model input parameters for configuration 3a +(analogue set @ B) as perceived at side B** + +| Input parameters | Values | Unit | +|-----------------------------------------------|----------------------------------------------------------|------| +| Send Loudness Rating (SLR A ) | 8 | dB | +| Receive Loudness Rating (RLR B ) | 0 | dB | +| Talker Echo Loudness Rating | 56 | dB | +| Weighted Echo Path Loss | 66 | dB | +| Equipment impairment factor (I e ) | 7 or 14 or 21 (unlicensed),
10 or 17 or 24 (licensed) | | +| Advantage factor (A) | 5 (unlicensed)
10 (licensed) | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 26 (unlicensed)
212 (licensed) | ms | +| Mean one-way delay | 13 (unlicensed)
106 (licensed) | ms | +| Absolute delay | 13 (unlicensed)
106 (licensed) | ms | + +#### B.2.7.3 Results + +##### B.2.7.3.1 Unlicensed: Wireless processing delay: 7 ms average (WUPE, PCI, PWT) + +![Bar chart titled 'Unlicensed: Wireless processing delay: 7 ms avg' showing E-Model Rating R for Side A and Side B across different numbers of low bit rate equipment (2 sets, 1 set, None).](a8aee5eac3467842490a713c009925f7_img.jpg) + +This bar chart displays the E-Model Rating R for two sides (Side A and Side B) under unlicensed wireless processing with a 7 ms average delay. The x-axis represents the number of low bit rate equipment sets (2 sets, 1 set, None). The y-axis represents the E-Model Rating R, ranging from 0 to 100. Side A is represented by dark gray bars, and Side B by white bars. The data is as follows: + +| # of low bit rate equipment | Side A | Side B | +|-----------------------------|--------|--------| +| 2 sets | 61.8 | 78.2 | +| 1 set | 68.8 | 85.2 | +| None | 75.8 | 92.2 | + +T1211560-99 + +Bar chart titled 'Unlicensed: Wireless processing delay: 7 ms avg' showing E-Model Rating R for Side A and Side B across different numbers of low bit rate equipment (2 sets, 1 set, None). + +Figure B.16a/G.108 – Unlicensed: Wireless processing delay: 7 ms avg + +##### B.2.7.3.2 Licensed: Wireless processing delay: 100 ms average (TDMA) + +![Bar chart titled 'Licensed: Wireless processing delay: 100 ms avg' showing E-Model Rating R for Side A and Side B across different numbers of low bit rate equipment (2 sets, 1 set, None).](7cf394a7ad158bf3aa4f8d58e7d4ebc5_img.jpg) + +This bar chart displays the E-Model Rating R for two sides (Side A and Side B) under licensed wireless processing with a 100 ms average delay. The x-axis represents the number of low bit rate equipment sets (2 sets, 1 set, None). The y-axis represents the E-Model Rating R, ranging from 0 to 100. Side A is represented by dark gray bars, and Side B by white bars. The data is as follows: + +| # of low bit rate equipment | Side A | Side B | +|-----------------------------|--------|--------| +| 2 sets | 18.4 | 74.1 | +| 1 set | 25.4 | 81.1 | +| None | 32.4 | 88.1 | + +T1211570-99 + +Bar chart titled 'Licensed: Wireless processing delay: 100 ms avg' showing E-Model Rating R for Side A and Side B across different numbers of low bit rate equipment (2 sets, 1 set, None). + +Figure B.16b/G.108 – Licensed: Wireless processing delay: 100 ms avg + +The results shown in Figures B.16a and B.16b indicate speech transmission quality perceived at side B is much better than that perceived at side A. The higher value of the ERL at side A provides a better echo cancellation and hence a better speech transmission quality to the opposite party B. + +Again, the more low bit-rate equipment is used, the poorer the resulting speech transmission quality. This observation is the same for both licensed and unlicensed technology. + +#### B.2.8 Reference configuration 3b (digital set @ side B) + +This configuration represents a private network connection with one termination consisting of a portable telephone set and the other termination a digital telephone set. This connection is the North American equivalent to reference configuration 3 in B.1 with a digital telephone set at side B. + +In configuration 3b, the portable (wireless set) at side A connects to digital PBX B by an ICS (ISDN Compatible Station) port. PBX A connects to transit PBX A via a Integrated Services Trunk (IST) port. The PBX loss is 0 dB in each direction, in accordance with the loss plan of [40] for ONS-IST connection. Transit PBX A connects the digital tie trunk (IST) to another digital tie trunk (IST). Per the PBX loss plan in [40], the loss for this PBX connection is 0 dB in both directions. This digital tie trunk connects to terminating digital PBX D. As shown, both tie trunk facilities use low bit-rate encoding equipment; the analysis for this connection is made for this case as well as for cases where only one or where neither tie trunk uses such equipment. PBX D connects to a digital telephone via an ICS port with 0 dB loss in each direction. + +Configuration 3b: portable set @ A; digital set @ B + +![Diagram of Configuration 3b showing signal flow from a portable set on Side A to a digital telephone on Side B through PBX B, PBX A, and PBX D. It includes loss values (SLR, RLR, ERL, 0 dB) and processing delays (1 ms, 1.5 ms) for each component. Echo paths for Side A and Side B are also shown.](3a568746c00925506d5c39f2a86a5a63_img.jpg) + +Technology + Unlicensed (PACS, WUPE, PCI, PWT) + Licensed + TDMA + +Average processing delay + 7 ms (ranges from 4-10 ms) + 100 ms (ranges from 70-100 ms) + +Diagram of Configuration 3b showing signal flow from a portable set on Side A to a digital telephone on Side B through PBX B, PBX A, and PBX D. It includes loss values (SLR, RLR, ERL, 0 dB) and processing delays (1 ms, 1.5 ms) for each component. Echo paths for Side A and Side B are also shown. + +Figure B.17/G.108 – Basis for calculation of reference configuration 3b + +##### B.2.8.1 Pre-calculations for configuration 3b + +##### B.2.8.1.1 Calculation of SLR, RLR and OLR + +###### Side A + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|-------------------------------|-------------------------------| +| Telephone set | SLR 8 dB | RLR 2 dB | +| PBX B | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRA = 8 dB | RLRA = 2 dB | + +###### Side B + +| | Set → 0 dBr point | 0 dBr point → Set | +|---------------------------|-------------------------------|-------------------------------| +| Telephone set | SLR 8 dB | RLR 2 dB | +| PBX D | 0 dB | 0 dB | +| PBX A | 0 dB | 0 dB | +| Sum at 0 dBr point | SLRB = 8 dB | RLRB = 2 dB | + +###### OLR + +| Listener at Side A | Listener at Side B | +|-------------------------|-------------------------| +| SLR B = 8 dB | SLR A = 8 dB | +| RLR A = 2 dB | RLR B = 2 dB | +| OLR = 10 dB | OLR = 10 dB | + +##### B.2.8.1.2 Talker Echo Loudness Rating (TELR) + +###### Analysis of TELR performed at Side A: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET A}} + \text{return loss (B)} + \text{sum of node losses} + \text{RLR}_{\text{SET A}} \\ + &= 8 + 45 + (0 + 0 + 0 + 0 + 0 + 0 + 0) + (2) \\ + &= 55 \text{ dB} + \end{aligned}$$ + +###### Analysis of TELR performed at Side B: + +$$\begin{aligned} + \text{TELR} &= \text{SLR}_{\text{SET B}} + \text{return loss (A)} + \text{sum of node losses} + \text{RLR}_{\text{SET B}} \\ + &= 8 + 45 + (0 + 0 + 0 + 0 + 0 + 0 + 0) + (2) \\ + &= 55 \text{ dB} + \end{aligned}$$ + +##### B.2.8.1.3 Weighted Echo Path Loss (WEPL) + +$$\begin{aligned} + \text{WEPL} &= \text{return loss (A)} + \text{return loss (B)} + \text{sum of node losses} \\ + &= 45 + 45 + (0 + 0 + 0 + 0 + 0 + 0 + 0) \\ + &= 90 \text{ dB} + \end{aligned}$$ + +##### B.2.8.1.4 Delay values T, Ta and Tr + +$$\begin{aligned} + T(\text{ms}) &= \text{Access delay of wireless technology} + \sum \text{PBX delay/end office delay} + \sum \text{low bit-rate equipment delay} \\ + &= 7 \text{ (unlicensed) or } 100 \text{ (licensed)} + 3 \times 1 + 2 \times 1.5 \\ + &= 13 \text{ or } 106 + \end{aligned}$$ + +$$T_a = T$$ + +$$T_r = 2 \times T$$ + +##### B.2.8.1.5 Number of quantization distortion units + +This parameter represents the impairments due to quantization distortion. It is entered as the number of quantization distortion units. Note that a value of 1 is used for the A/D-D/A conversion. Digital loss pads have additional qdu value of 0.7. In this scenario, there are altogether 1 pair of A/D-D/A conversion for either side analysis. + +Therefore, $qdu = n \times 1 + m \times 0.7$ + +$$= 1 \times 1 + 1 \times 0.7$$ + +$$= 1.7$$ + +where $n$ = number of A/D-D/A conversion pairs + +$m$ = number of digital pads + +##### B.2.8.1.6 Equipment impairment factor + +The codec used for wireless technology does have an impact on speech transmission quality. For the two types of technology analysed, values in Table 2a were used. The total equipment impairment factor ( $I_e$ ) is the sum of all the equipment impairment factors involved: + +$I_e$ = $I_e$ value for codec used in wireless technology + $I_e$ value for network LBR equipment + +$$= 7 \text{ (unlicensed)} \text{ or } 10 \text{ (licensed)} + 0 \text{ (0 LBR)} \text{ or } 7 \text{ (1 LBR)} \text{ or } 14 \text{ (2 LBR)}$$ + +$$= 7 \text{ or } 14 \text{ or } 21 \text{ (unlicensed)} \quad \text{or}$$ + +$$= 10 \text{ or } 17 \text{ or } 24 \text{ (licensed)}.$$ + +#### B.2.8.2 Input parameters summary tables + +The input parameters for configuration 3b (digital set @ B) are summarized in Tables B.6a and B.6b; all other parameter remain at their default values according to Table 6. + +**Table B.6a/G.108 – E-Model input parameters for configuration 3b +(digital set @ B) as perceived at side A** + +| Input parameters | Values | Unit | +|---------------------------------------|---------------------------------------------------------|------| +| Send Loudness Rating ( $SLR_B$ ) | 8 | dB | +| Receive Loudness Rating ( $RLR_A$ ) | 2 | dB | +| Talker Echo Loudness Rating | 55 | dB | +| Weighted Echo Path Loss | 90 | dB | +| Equipment impairment factor ( $I_e$ ) | 7 or 14 or 21 (unlicensed)
10 or 17 or 24 (licensed) | | +| Advantage factor ( $A$ ) | 5 (unlicensed),
10 (licensed) | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 26 (unlicensed)
212 (licensed) | ms | +| Mean one-way delay | 13 (unlicensed)
106 (licensed) | ms | +| Absolute delay | 13 (unlicensed)
106 (licensed) | ms | + +**Table B.6b/G.108 – E-Model input parameters for configuration 3b +(digital set @ B) as perceived at side B** + +| Input parameters | Values | Unit | +|-----------------------------------------------|---------------------------------------------------------|------| +| Send Loudness Rating (SLR A ) | 8 | dB | +| Receive Loudness Rating (RLR B ) | 2 | dB | +| Talker Echo Loudness Rating | 55 | dB | +| Weighted Echo Path Loss | 90 | dB | +| Equipment impairment factor (I e ) | 7 or 14 or 21 (unlicensed)
10 or 17 or 24 (licensed) | | +| Advantage factor (A) | 5 (unlicensed),
10 (licensed) | | +| Quantization distortion unit | 1.7 | | +| Round trip delay | 26 (unlicensed)
212 (licensed) | ms | +| Mean one-way delay | 13 (unlicensed)
106 (licensed) | ms | +| Absolute delay | 13 (unlicensed)
106 (licensed) | ms | + +##### B.2.8.3 Results + +###### B.2.8.3.1 Unlicensed: Wireless processing delay: 7 ms average (WUPE, PCI, PWT) + +![Bar chart showing E-Model Rating R for Side A and Side B across different numbers of low bit rate equipment (2 sets, 1 set, None).](0900604c8cc7befdd4d60d2d4f3b17d4_img.jpg) + +Unlicensed: Wireless processing delay: 7 ms avg + +| # of low bit rate equipment | Side A | Side B | +|-----------------------------|--------|--------| +| 2 sets | 77.1 | 77.1 | +| 1 set | 84.1 | 84.1 | +| None | 91.1 | 91.1 | + +T1211590-99 + +Bar chart showing E-Model Rating R for Side A and Side B across different numbers of low bit rate equipment (2 sets, 1 set, None). + +**Figure B.17a/G.108 – Unlicensed: Wireless processing delay: 7 ms avg** + +##### B.2.8.3.2 Licensed: Wireless processing delay: 100 ms average (TDMA) + +![Bar chart titled 'Licensed: Wireless processing delay: 100 ms avg' showing E-Model Rating R for Side A and Side B across three categories of low bit rate equipment: 2 sets, 1 set, and None. The y-axis ranges from 0 to 100. The x-axis is labeled '# of low bit rate equipment'. The legend indicates Side A is dark gray and Side B is light gray. Data values are: 2 sets (72.3, 72.3), 1 set (79.3, 79.3), and None (86.3, 86.3).](39dfa32741836e2dffe40299334e9c74_img.jpg) + +| # of low bit rate equipment | Side A | Side B | +|-----------------------------|--------|--------| +| 2 sets | 72.3 | 72.3 | +| 1 set | 79.3 | 79.3 | +| None | 86.3 | 86.3 | + +Bar chart titled 'Licensed: Wireless processing delay: 100 ms avg' showing E-Model Rating R for Side A and Side B across three categories of low bit rate equipment: 2 sets, 1 set, and None. The y-axis ranges from 0 to 100. The x-axis is labeled '# of low bit rate equipment'. The legend indicates Side A is dark gray and Side B is light gray. Data values are: 2 sets (72.3, 72.3), 1 set (79.3, 79.3), and None (86.3, 86.3). + +Figure B.17b/G.108 – Licensed: Wireless processing delay: 100 ms avg + +As shown in Figure B.17a, speech transmission quality perceived at either side A or side B is the same as the value of ERL at either end is the same value (45 dB), resulting in speech transmission quality performance in the satisfied region. The same observation is obtained in Figure B.17b for licensed technology. The only difference is the lower value in absolute terms for licensed technology because of the longer delay and the higher impairment factor. + +### B.3 Planning example for IP transmission based scenarios + +Table B.7 shows sample E-Model calculations for several IP telephony scenarios. An "impairment-free" connection with 50 ms one-way delay is included as a reference. Such a connection meets the delay allocation for a national segment as defined in Recommendation G.114 [6]. + +The only E-Model parameters that have been varied are the equipment impairment factor of the codec and the delay. All other parameters are set to the default values shown in Table 6. In particular, effects of channel errors, packet loss and delay variability are not included. + +The equipment impairment factors are taken from the current Appendix I/G.113 [5]. + +One-way delay for a given IP telephony system is determined by the network delay and the number of encoded frames that are included in each IP packet (see 7.3.2.3). A lost packet will result in speech clipping. In order to maintain a good end-to-end speech transmission performance, the speech contained in coded frames should be less than 64 ms of speech per IP packet (see 7.5 on Temporal (Syllable) Clipping Recommendation G.177 [13]). Hence, at most two frames of G.723.1, or six frames of G.729A, are assembled into a packet. In Table B.7, the "packet delay" column is the time required for the assembly of a packet including the encoding and decoding process, and is computed as: + +$$T_F(N + 1) + T_L$$ + +where $T_F$ is the frame size for the codec, $N$ is the number of frames in a packet, and $T_L$ is the look-ahead time for the codec. For G.723.1 (both bit rates), the frame size is 30 ms and the look-ahead is 7.5 ms. For G.729A, the frame size is 10 ms and the look-ahead is 5 ms. + +**Table B.7/G.108 – Example E-Model calculations for IP telephony** + +| Codec | Equipment impairment factor (I e ) | # frames/packet | Packet delay (ms) | Network delay (ms) | End-to-end mean one-way delay (ms) | E-Model Rating R | +|---------------|-----------------------------------------------|-----------------|-------------------|--------------------|------------------------------------|------------------| +| G.711 (PSTN) | 0 | N/A | N/A | 50 | 50 | 92.7 | +| G.723.1 (5.3) | 19 | 1 | 67.5 | 50 | 117.5 | 72.3 | +| G.723.1 (5.3) | 19 | 2 | 97.5 | 50 | 147.5 | 71.6 | +| G.723.1 (6.3) | 15 | 1 | 67.5 | 50 | 117.5 | 76.3 | +| G.723.1 (6.3) | 15 | 2 | 97.5 | 50 | 147.5 | 75.6 | +| G.729A | 11 | 1 | 25 | 50 | 75 | 81.1 | +| G.729A | 11 | 2 | 35 | 50 | 85 | 80.9 | +| G.729A | 11 | 3 | 45 | 50 | 95 | 80.7 | +| G.729A | 11 | 4 | 55 | 50 | 105 | 80.5 | +| G.729A | 11 | 5 | 65 | 50 | 115 | 80.3 | +| G.729A | 11 | 6 | 75 | 50 | 125 | 80.1 | + +NOTE – Equipment impairment factors (Ie) for Recommendations G.723.1 and G.729A are for the codec with voice activity detection turned on. See text for details on delay values. + +Table B.8 shows R-values for indicated combinations of Ie and end-to-end mean one-way delay. Note that the different shadings relate to the different categories of speech transmission quality as defined in Table 1. + +**Table B.8/G.108 – E-Model Ratings R for indicated combinations of Ie and end-to-end mean one-way delay** + +| I e = | 0 | 5 | 7 | 10 | 15 | 19 | 19 | 20 | 26 | +|------------------|-------|---------|-----------|-------|--------------|-----------------------|----------------------------|--------|-----------------------| +| | G.711 | GSM-EFR | G.726 @32 | G.729 | G.723.1 @6.3 | G.729A +VAD w/2% loss | G.723.1 @5.3 | GSM-FR | G.729A +VAD w/4% loss | +| ms | | | G.728 @16 | | | | G.723.1 @6.3+VAD w/1% loss | IS-54 | | +| ~0 | 94 | | 87 | | | | | | | +| 50 | 93 | | 86 | 83 | | 74 | | | 67 | +| 100 | 92 | 87 | 85 | 82 | 77 | 73 | 73 | 72 | 66 | +| 150 | 90 | 85 | 83 | 80 | 75 | 71 | 71 | 70 | 64 | +| 200 | 87 | 82 | 80 | 77 | 72 | 68 | 68 | 67 | 61 | +| 250 | 80 | 75 | 73 | 70 | 65 | 61 | 61 | 60 | 54 | +| 300 | 74 | 69 | 67 | 64 | 59 | 55 | 55 | 54 | 48 | +| 350 | 68 | 63 | 61 | 58 | 53 | 49 | 49 | 48 | 42 | +| 400 | 63 | 58 | 56 | 53 | 48 | 44 | 44 | 43 | 37 | +| 450 | 59 | 54 | 52 | 49 | 44 | 40 | 40 | 39 | 33 | + +NOTE 1 – R-values in this table have been calculated using the indicated values for Ie and T (T=Ta=Tr/2) along with the default values from Table 6 for all other parameters. +NOTE 2 – Unless indicated otherwise, examples do not include packet loss or Voice Activity Detection (VAD). +NOTE 3 – Blackened cells indicate combinations of delay and codec that are impossible to realize. + +## Echo control in specific applications + +In traditional networks, the insertion of echo control devices was mainly necessary for international connections. Usually they were located in international switching centres and, therefore, in most cases, within the responsibility of public network operators. The increasing use of digital routing in conjunction with equipment using low bit-rate coding has changed these previous rules. Additional transmission delay may now be arising due to the processing delays of specific equipment such as multiplexers, voice activity detection circuits, mobile and cordless telephones, equipment which are used more in the lower hierarchy of public networks or directly within private networks. + +In case calls are being routed, e.g. via multiplexing equipment or are being terminated with mobile or specific cordless telephones, the additional delay introduced into a connection may have such a high value, that echo control devices are necessary even for national calls, hence in international calls the permissible echo path delay of the echo canceller in an international switching centre could be exceeded. Therefore, in most applications those multiplexers or terminals are equipped with "integrated" echo control devices to guarantee sufficient echo control for every type of connection. However, these integrated echo control devices should be considered carefully during planning to avoid incorrect range of operation and insufficient interworking with other echo control devices. + +The following clauses describe the different aspects which should be considered for those types of integrated echo control devices referring, as an example, to a cordless telephone according to [50] and [53] inserting an additional mean one-way delay of about 14 ms. + +### C.1 Effective echo paths + +The fixed part of a cordless telephone (base station) can be connected either 2-wire analogue or digital to a switching element (e.g. PBX in a private network). If this terminal within the private network is connected to another terminal via a public network, several echo paths may be effective as shown in Figure C.1, which should be identified and investigated during planning. + +The different echo paths in this configuration are described in the following subclauses: + +#### C.1.1 Echo path 1: for talker at the cordless telephone + +This echo path is only effective if the fixed part is connected 2-wire analogue via a hybrid to the PBX. This hybrid is forming an echo path for the talker at the cordless telephone with a mean one-way delay of 14 ms, a value which requires echo control. + +#### C.1.2 Echo path 2: for talker at the cordless telephone + +This echo path via the public network is effective if the far end is terminated with a 4-wire to 2-wire conversion (hybrid). For planning purposes, however, at present this should be assumed in most cases. This echo path is independent of the type of access of the fixed part (2-wire analogue or digital) and its mean one-way delay is including the delay of the public/private network and is, therefore, in any case higher than for echo path 1. Both echo paths 1 and 2 each with different mean one-way delay and different TELR values can be effective for the talker at the cordless telephone at the same time. Therefore, the cordless telephone should be equipped with echo control devices able to control both types of echo. + +#### C.1.3 Echo path 3: for talker at the cordless telephone + +This echo path via the acoustic coupling of the far-end telephone set usually is negligible compared to the impairments caused by echo paths 1 and 2. Although the mean one-way delay can be higher than for echo path 2, e.g. if a cordless telephone according to DECT standard is used on both sides, + +the resulting impairment will be low, since the corresponding TELR for this echo path can be expected with more than 44 dB. + +![Diagram illustrating possible echo paths for a cordless telephone. The diagram is divided into three main sections: 'Portable part', 'Fixed part', and 'Private and/or public network'. The 'Portable part' contains a microphone, a side-tone STMR, and two transceivers labeled 't'. The 'Fixed part' contains an Echo Control Device (ECD). The 'Private and/or public network' section shows various network components including switches and an Echo Canceller (EC) at an 'international access' point. Six echo paths are indicated: Echo path 1 (within the fixed part), Echo path 2 (within the fixed part), Echo path 3 (within the private/public network), Echo path 4 (within the private/public network), Echo path 5 (within the private/public network), and Echo path 6 (within the private/public network, ending at the international access). A legend at the bottom defines ECD as 'Echo Control Devices (within cordless telephone)' and EC as 'Echo Canceller (within public network)'. The diagram is labeled T1211610-99.](69d00e8adf9811292427fb2ce6712e39_img.jpg) + +ECD Echo Control Devices (within cordless telephone) +EC Echo Canceller (within public network) + +T1211610-99 + +Diagram illustrating possible echo paths for a cordless telephone. The diagram is divided into three main sections: 'Portable part', 'Fixed part', and 'Private and/or public network'. The 'Portable part' contains a microphone, a side-tone STMR, and two transceivers labeled 't'. The 'Fixed part' contains an Echo Control Device (ECD). The 'Private and/or public network' section shows various network components including switches and an Echo Canceller (EC) at an 'international access' point. Six echo paths are indicated: Echo path 1 (within the fixed part), Echo path 2 (within the fixed part), Echo path 3 (within the private/public network), Echo path 4 (within the private/public network), Echo path 5 (within the private/public network), and Echo path 6 (within the private/public network, ending at the international access). A legend at the bottom defines ECD as 'Echo Control Devices (within cordless telephone)' and EC as 'Echo Canceller (within public network)'. The diagram is labeled T1211610-99. + +**Figure C.1/G.108 – Possible echo paths for a cordless telephone** + +#### C.1.4 Echo path 4: for talker of the public network + +For the echo path being effective here for the talker at the public network side, in principle the same issues are valid as for echo path 3. For planning purposes it is necessary only to investigate whether the provided TCLw referred to the fixed part amounts to more than 34 dB if the path within the private network is fully digital. + +#### C.1.5 Echo path 5: for talker of the public network + +This echo path is mentioned here only for the sake of completeness since the requirements for a sufficient echo loss referred to the interface between public and private network are in this case independent from the type of terminal equipment and its mean one-way delay. Echo path 5 will in normal configurations contribute with higher impairments than echo path 4 due to the lower value of only 24 dB for the echo loss. + +#### C.1.6 Echo path 6: for talker of the public network in an international call + +Although comparable with echo path 5, this configuration should be considered separately due to the echo canceller which is automatically enabled within the international switching centre because of the international connection. The characteristics of these echo cancellers, presently designed according to Recommendations G.165 [11] or G.168 [12], are usually not adapted to the additional + +delay and the high values of TCLw of a terminating cordless telephone. Therefore, precautions should be taken to guarantee a proper operation of this echo canceller. + +### C.2 Operation of echo cancellers and soft suppressors + +The main devices in a cordless telephone according to the DECT standard for the control of echo along the different echo paths are shown in principle in Figure C.2. For the given configuration of a 2-wire analogue connection to the private/public network the two echo paths 1 and 2 should be considered. The analogue access requires not only a hybrid but also an adjustment of the SLR and RLR of the cordless terminal (including the fixed part) to national requirements. The DECT standard in general specifies values of $SLR = 7$ dB and $RLR = 3$ dB referred to an internal reference point (0 dBr-point). To meet the national requirements at the 2-wire interface of the fixed part (in this example $SLR = +3$ dB, $RLR = -8$ dB) a gain of 4 dB in the transmit path and of 11 dB in the receive path are adjusted within the hybrid. Assuming a proper impedance strategy (see C.1.3) an average terminal balance return loss of $a_{BRL} = 18$ dB can be estimated; the resulting transhybrid loss of $a_{TRH} = -3$ dB is very low and could cause remarkable impairments. To suppress this "near-end echo" of echo path 1 two devices, the echo canceller EC and the soft suppressor (SS) are inserted between the so called UPCM-interfaces (Uniform-PCM). + +The principle of the echo canceller is in accordance with the description in Recommendation G.165 [11] or G.168 [12], but without the NLP and with less stringent requirements. The corresponding standard requires only an enhancement of the transhybrid loss, called echo loss enhancement, of $> 6.5$ dB, which is resulting in an echo loss of $-3$ dB $+ 6.5$ dB $= 9.5$ dB in the example as shown in Figure C.2. Furthermore, the permissible echo path delay for this EC is required with only $> 4$ ms, since only the hybrid circuit is forming the echo path. + +![Figure C.2/G.108 – Echo control devices in a DECT cordless telephone. The diagram illustrates the signal flow and echo paths in a DECT terminal connected to a public/private network. On the left, a microphone and handset are connected to A/D and D/A converters. The transmit path (top) goes from the microphone through a PCM encoder, a UP PCM interface, an Echo Canceller (EC) with Echo Loss Enhancement (ELE > 6.5 dB), and another UP PCM interface to the network. The receive path (bottom) goes from the network through a D/A converter, a PCM decoder, and a Soft Suppressor (SS) with a 9 dB loss, then through a UP PCM interface, the EC, and another UP PCM interface to the handset. Various gain and loss parameters are indicated: SLR (0 dBr) = 7 dB, a_s = -4 dB, RLR (0 dBr) = 3 dB, a_R = -11 dB, a_THL > 3 dB, and TELR > 28.5 dB. Time delays of t = 14 ms and t = 0 are shown for different signal points. Two echo paths are identified: Echo path 1 (near-end echo) and Echo path 2 (far-end echo). The DECT terminal is described as having adaptation to analogue access with SLR = 4 dB and RLR = -8 dB.](8a9a4dc9f8f886d283f9a75e5b2287f4_img.jpg) + +Figure C.2/G.108 – Echo control devices in a DECT cordless telephone. The diagram illustrates the signal flow and echo paths in a DECT terminal connected to a public/private network. On the left, a microphone and handset are connected to A/D and D/A converters. The transmit path (top) goes from the microphone through a PCM encoder, a UP PCM interface, an Echo Canceller (EC) with Echo Loss Enhancement (ELE > 6.5 dB), and another UP PCM interface to the network. The receive path (bottom) goes from the network through a D/A converter, a PCM decoder, and a Soft Suppressor (SS) with a 9 dB loss, then through a UP PCM interface, the EC, and another UP PCM interface to the handset. Various gain and loss parameters are indicated: SLR (0 dBr) = 7 dB, a\_s = -4 dB, RLR (0 dBr) = 3 dB, a\_R = -11 dB, a\_THL > 3 dB, and TELR > 28.5 dB. Time delays of t = 14 ms and t = 0 are shown for different signal points. Two echo paths are identified: Echo path 1 (near-end echo) and Echo path 2 (far-end echo). The DECT terminal is described as having adaptation to analogue access with SLR = 4 dB and RLR = -8 dB. + +Figure C.2/G.108 – Echo control devices in a DECT cordless telephone + +To increase the echo loss of only 9.5 dB an additional device, the soft suppressor (SS) is inserted. This SS is in its operational mode comparable with an echo suppressor. If the talker's voice signal is detected in the transmit path, an additional loss of 9 dB is enabled in the receive path during talking, + +increasing the echo loss to 18.5 dB. Together with the SLR and RLR at the 0 dBr-point the total TELR is 28.5 dB, which is sufficient for this echo in echo path 1. + +For echo path 2, an echo loss of 24 dB with an additional mean one-way delay of 30 ms via the public network is assumed. The echo canceller (EC) is unable to compensate this echo path due to the low value of 4 ms for the permissible echo path delay. In this case only the soft suppressor (SS) is, during talking, increasing the echo loss from 24 dB to 33 dB, resulting in a sufficiently high value of 41 dB for the TELR. + +### C.3 Provision of echo control for the talker of the public network + +For the far-end talker provisions should be made by the private network subject to planning for a sufficient high value of TELR. The effective echo paths for this talker are the paths 4, 5 and 6 as shown in Figure C.1. If the connection is terminated within the private network by a hybrid the value for TELR is stated with 24 dB in 7.7 and is not considered here. + +For a fully digital routing within the private network and termination by a cordless telephone, the echo loss is identical with the TCLw of the portable part. For cordless telephones according to the DECT standard basically a TCLw of > 46 dB is required, however, also only 34 dB are allowed as an option. For the echo path of national calls (echo path 4 in Figure C.1) this value is providing a sufficiently high value of TELR = 44 dB (assuming SLR = 7 dB and RLR = 3 dB for the far-end termination with respect to the public/private network interface). + +For international connections with an enabled echo canceller within the public network, this high value of TELR in conjunction with the additional mean one-way delay of 14 ms may cause an improper operation of this echo canceller. Therefore, if the portable part is only providing the optional TCLw of 34 dB an artificial echo loss (AE) should be inserted at the network-side of the fixed part. This configuration is shown in Figure C.3. + +![Figure C.3/G.108 – TCLw and artificial echo loss. This block diagram illustrates the signal flow and echo paths for a DECT telephone connected to a private/public network. On the left, a 'DECT - Telephone' consists of a handset connected to a base station via A/D converters. The base station contains PCM (Pulse Code Modulation) units. The signal path from the handset to the network interface has a one-way delay of t = 14 ms and an echo loss of SLR = 7 dB. The return path from the network interface back to the handset has a one-way delay of t = 14 ms and an echo loss of RLR = 3 dB. At the network interface, labeled '0 dBr', an Artificial Echo Loss (AE) block is inserted. The signal then enters the 'Private/public network', which has a one-way delay of t > 20 ms. Within the network, an 'Echo loss = 24 dB' block is shown, followed by an 'EC' (Echo Canceller) block. The signal then reaches 'International access'. A dashed line labeled 'Echo path 6' shows the echo return from the EC block back through the network. A label 'T1211630-99' is present in the bottom right corner of the diagram area.](4d45c2b40c053dd2b36d2c1f9271728e_img.jpg) + +Figure C.3/G.108 – TCLw and artificial echo loss. This block diagram illustrates the signal flow and echo paths for a DECT telephone connected to a private/public network. On the left, a 'DECT - Telephone' consists of a handset connected to a base station via A/D converters. The base station contains PCM (Pulse Code Modulation) units. The signal path from the handset to the network interface has a one-way delay of t = 14 ms and an echo loss of SLR = 7 dB. The return path from the network interface back to the handset has a one-way delay of t = 14 ms and an echo loss of RLR = 3 dB. At the network interface, labeled '0 dBr', an Artificial Echo Loss (AE) block is inserted. The signal then enters the 'Private/public network', which has a one-way delay of t > 20 ms. Within the network, an 'Echo loss = 24 dB' block is shown, followed by an 'EC' (Echo Canceller) block. The signal then reaches 'International access'. A dashed line labeled 'Echo path 6' shows the echo return from the EC block back through the network. A label 'T1211630-99' is present in the bottom right corner of the diagram area. + +**Figure C.3/G.108 – TCLw and artificial echo loss** + +The purpose of this artificial echo loss (AE) (a directional loss from digital in to digital out) is to provide a "virtual" echo path with an "in-range" echo loss of 24 dB and excluding the additional delay of 14 ms from the cordless telephone. Residual echo levels via the TCLw and including this additional delay are suppressed by the NLP of the echo canceller in the public network, because these residual echo levels are now well below the threshold of the NLP. + + + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure | +| Series Z | Languages and general software aspects for telecommunication systems | + +\*17913\* \ No newline at end of file diff --git a/marked/G/T-REC-G.114-200305-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.114-200305-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..939eb6a57fac47a375526475ba6c31bf67e08b30 --- /dev/null +++ b/marked/G/T-REC-G.114-200305-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:52a289bbb49d106b16f646b5050f62e5c7cbe1bb201f8c767547c3039abbf359 +size 8245 diff --git a/marked/G/T-REC-G.114-200305-I_PDF-E/4e4be0bd8b235167902f2c03e41da651_img.jpg b/marked/G/T-REC-G.114-200305-I_PDF-E/4e4be0bd8b235167902f2c03e41da651_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..b0336d775f8613ce563899e6fa61daa8bb344494 --- /dev/null +++ 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a/marked/G/T-REC-G.165-199303-I_PDF-E/raw.md b/marked/G/T-REC-G.165-199303-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..de4d0059eddfde85d465e628815310e68ae0c19f --- /dev/null +++ b/marked/G/T-REC-G.165-199303-I_PDF-E/raw.md @@ -0,0 +1,952 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.165** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(03/93) + +# **GENERAL CHARACTERISTICS OF INTERNATIONAL TELEPHONE CONNECTIONS AND INTERNATIONAL TELEPHONE CIRCUITS** --- + +# **ECHO CANCELLERS** + +**ITU-T Recommendation G.165** + +(Previously "CCITT Recommendation") + +--- + +# FOREWORD + +The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecommunication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +ITU-T Recommendation G.165 was revised by the ITU-T Study Group XV (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). + +# --- NOTES + +1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. + +In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms "CCITT, CCIR or IFRB" or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. + +2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# CONTENTS + +*Page* + +| | | | +|------|--------------------------------------------------------------------------------------------------------|----| +| 1 | General ..... | 1 | +| 2 | Definitions relating to echo cancellers ..... | 3 | +| 2.1 | echo canceller ..... | 3 | +| 2.2 | echo loss ( $A_{\text{ECHO}}$ ) ..... | 3 | +| 2.3 | pure delay ( $t_r$ ) ..... | 3 | +| 2.4 | (near-end) echo path or end delay ( $t_d$ ) ..... | 4 | +| 2.5 | cancellation ( $A_{\text{CANC}}$ ) ..... | 4 | +| 2.6 | residual echo level ( $L_{\text{RES}}$ ) ..... | 4 | +| 2.7 | nonlinear processor (NLP) ..... | 4 | +| 2.8 | nonlinear processing loss ( $A_{\text{NLP}}$ ) ..... | 4 | +| 2.9 | returned echo level ( $L_{\text{RET}}$ ) ..... | 5 | +| 2.10 | combined loss ( $A_{\text{COM}}$ ) ..... | 5 | +| 2.11 | convergence ..... | 5 | +| 2.12 | convergence time ..... | 5 | +| 2.13 | leak time ..... | 5 | +| 3 | Characteristics of echo cancellers ..... | 5 | +| 3.1 | General ..... | 5 | +| 3.2 | Purpose, operation and environment ..... | 6 | +| 3.3 | External enabling/disabling ..... | 8 | +| 3.4 | Tests and requirements for performance with inputs signals applied to the send and receive paths ..... | 8 | +| 4 | Characteristics of an echo canceller tone disabler ..... | 16 | +| 4.1 | General ..... | 16 | +| 4.2 | Disabler characteristics ..... | 16 | +| 4.3 | Guardband characteristics ..... | 16 | +| 4.4 | Holding-band characteristics ..... | 17 | +| 4.5 | Operate time ..... | 17 | +| 4.6 | False operation due to speech currents ..... | 17 | +| 4.7 | False operation due to data signals ..... | 17 | +| 4.8 | Release time ..... | 17 | +| 4.9 | Other considerations ..... | 17 | +| 5 | Nonlinear processors for use in echo cancellers ..... | 17 | +| 5.1 | Scope ..... | 17 | +| 5.2 | General principles and guidelines ..... | 18 | +| | Annex A – Echo cancellers without nonlinear processing ..... | 21 | +| | Annex B – Description of an echo canceller reference tone disabler ..... | 22 | +| B.1 | General ..... | 22 | +| B.2 | Disabler characteristics ..... | 22 | +| B.3 | Guardband characteristics ..... | 22 | +| B.4 | Holding-band characteristics ..... | 22 | +| B.5 | Operate time ..... | 22 | +| B.6 | False operation due to speech currents ..... | 22 | +| B.7 | False operation due to data signals ..... | 23 | +| B.8 | Release time ..... | 23 | + +| | Page | +|----------------------------------------------------------------|-------------| +| Annex C – Description of a reference nonlinear processor ..... | 23 | +| C.1    General..... | 23 | +| C.2    Suppression threshold ( $T_{\text{SUP}}$ ) ..... | 24 | +| C.3    Static characteristics of activation control ..... | 24 | +| C.4    Dynamic characteristics of activation control..... | 24 | +| C.5    Frequency limits of control paths ..... | 24 | +| C.6    Testing ..... | 24 | + +# ECHO CANCELLERS + +*(Geneva, 1980; amended at Malaga-Torremolinos, 1984; +at Melbourne, 1988 and at Helsinki, 1993)* + +# 1 General + +1.1 Echo cancellers are voice operated devices placed in the 4-wire portion of a circuit (which may be an individual circuit path or a path carrying a multiplexed signal) and are used for reducing the echo by subtracting an estimated echo from the circuit echo. They may be characterized by whether the transmission path or the subtraction of the echo is by analogue or digital means (see Figures 1, 2 and 3). + +1.2 This Recommendation is applicable to the design of echo cancellers using digital or analogue techniques, and intended for use in an international circuit. Echo cancellers designed to this Recommendation will be compatible with each other and with echo suppressors designed in accordance with Recommendation G.164. Compatibility is defined in 1.4/G.164. Freedom is permitted in design details not covered by the requirements. + +Echo cancellers may be used for purposes other than network echo control on international or mobile telephony circuits, e.g. in active 2-wire/4-wire hybrids or 2-wire repeaters, but this Recommendation does not apply to such echo cancellers. + +![Block diagram of a Type A echo canceller. It shows a send path and a receive path. The send path starts at Sin, goes through an Analogue subtractor, and exits as Sout. The receive path starts at Rin, goes through an Echo estimator and other control circuitry, and exits as Rout. Both paths are labeled 'Analogue path'. The Analogue subtractor and the Echo estimator are interconnected. A reference signal from the Sout line is fed into the Echo estimator. The Echo estimator outputs an estimated echo signal to the Analogue subtractor. The Analogue subtractor then subtracts this estimated echo from the incoming signal at Sin to produce the final output at Sout. The receive path is a direct connection from Rin to Rout, passing through the Echo estimator block.](1b896a95bc9974ad01fac7ac6f541a96_img.jpg) + +Block diagram of a Type A echo canceller. It shows a send path and a receive path. The send path starts at Sin, goes through an Analogue subtractor, and exits as Sout. The receive path starts at Rin, goes through an Echo estimator and other control circuitry, and exits as Rout. Both paths are labeled 'Analogue path'. The Analogue subtractor and the Echo estimator are interconnected. A reference signal from the Sout line is fed into the Echo estimator. The Echo estimator outputs an estimated echo signal to the Analogue subtractor. The Analogue subtractor then subtracts this estimated echo from the incoming signal at Sin to produce the final output at Sout. The receive path is a direct connection from Rin to Rout, passing through the Echo estimator block. + +$R_{in}$ Receive-in port + $R_{out}$ Receive-out port + $S_{in}$ Send-in port + $S_{out}$ Send-out port + +FIGURE 1/G.165 +**Type A echo canceller** + +![Block diagram of a Type C echo canceller. The diagram shows a 'Send path' and a 'Receive path' enclosed in a dashed box. In the 'Send path', an input signal S_in enters a 'Digital subtractor'. The output of the subtractor is S_out. In the 'Receive path', an input signal R_in enters the 'Digital subtractor' from the right. The output of the subtractor on the left is R_out. Below the subtractor is an 'Echo estimator and other control circuitry' block. This block receives inputs from both the S_in and R_in lines and provides control signals to the 'Digital subtractor'. The entire system is labeled 'Digital path' on both sides. A reference code 'T1513650-93/d02' is at the bottom right.](547f726730e589392f239257a833ede3_img.jpg) + +Block diagram of a Type C echo canceller. The diagram shows a 'Send path' and a 'Receive path' enclosed in a dashed box. In the 'Send path', an input signal S\_in enters a 'Digital subtractor'. The output of the subtractor is S\_out. In the 'Receive path', an input signal R\_in enters the 'Digital subtractor' from the right. The output of the subtractor on the left is R\_out. Below the subtractor is an 'Echo estimator and other control circuitry' block. This block receives inputs from both the S\_in and R\_in lines and provides control signals to the 'Digital subtractor'. The entire system is labeled 'Digital path' on both sides. A reference code 'T1513650-93/d02' is at the bottom right. + +NOTE – Functionally, a type C digital echo canceller (DEC) interfaces at 64 kbit/s. However, 24 or 30 digital echo cancellers for example may be combined corresponding to the primary digital hierarchy levels of 1544 kbit/s or 2048 kbit/s, respectively. + +FIGURE 2/G.165 +**Type C echo canceller** + +![Block diagram of a Type D echo canceller. The diagram shows a 'Send path' and a 'Receive path' enclosed in a dashed box. On the left, an input signal S_in enters a vertical 'CODEC' block. The output of this CODEC enters a 'Analogue subtractor'. On the right, the output of the 'Analogue subtractor' enters another vertical 'CODEC' block, which produces the output signal S_out. In the 'Receive path', an input signal R_in enters the right 'CODEC' block from the right. The output of this CODEC on the left is R_out. Below the subtractor is an 'Echo estimator and other control circuitry' block. This block receives inputs from the lines between the CODECs and provides control signals to the 'Analogue subtractor'. The entire system is labeled 'Analogue path' on both sides. A reference code 'T1513660-93/d03' is at the bottom right.](88b0f3f4393228e9ea4d6542aef7c399_img.jpg) + +Block diagram of a Type D echo canceller. The diagram shows a 'Send path' and a 'Receive path' enclosed in a dashed box. On the left, an input signal S\_in enters a vertical 'CODEC' block. The output of this CODEC enters a 'Analogue subtractor'. On the right, the output of the 'Analogue subtractor' enters another vertical 'CODEC' block, which produces the output signal S\_out. In the 'Receive path', an input signal R\_in enters the right 'CODEC' block from the right. The output of this CODEC on the left is R\_out. Below the subtractor is an 'Echo estimator and other control circuitry' block. This block receives inputs from the lines between the CODECs and provides control signals to the 'Analogue subtractor'. The entire system is labeled 'Analogue path' on both sides. A reference code 'T1513660-93/d03' is at the bottom right. + +FIGURE 3/G.165 +**Type D echo canceller** + +**1.3** The tests in this Recommendation focus on band-limited noise performance. Echo cancellers passing these tests may nevertheless perform poorly on speech. It is recommended that designers and/or users of echo cancellers ensure adequate speech performance as recommended in 3.4.2. + +Furthermore, network echo cancellers must perform adequately on many non-speech signals as well, e.g. voice-band data, and that performance is not dealt with at all in this Recommendation. Tests have shown that not all echo cancellers passing the tests in clause 3 are guaranteed to perform correctly on voice-band data traffic, in particular on Group 3 facsimile signals. Additional tests to address this problem are under study but it is recommended that designers and/or users of echo cancellers ensure adequate voice-band data performance in addition to passing tests in clause 3. + +# 2 Definitions relating to echo cancellers1) + +In the definition and text, $L$ will refer to the relative power level of a signal, expressed in dBm0 and $A$ will refer to the attenuation or loss of a signal path expressed in dB. + +### 2.1 echo canceller + +*F: annuleur d'écho* + +*S: compensador de eco; cancelador de eco* + +A voice operated device placed in the 4-wire portion of a circuit and used for reducing near-end echo present on the send path by subtracting an estimation of that echo from the near-end echo (see Figure 4). + +![Block diagram of an echo canceller. A 'Hybrid' block on the left has a 'Near end' input and two output ports: S_in and R_out. The S_in port is the input to the 'Send path' (indicated by a dashed line). The R_out port is the input to the 'Receive path' (indicated by a dashed line). Inside the 'Send path', the signal from S_in goes to a 'Subtractor' block. The 'Subtractor' also receives an input from an 'Echo estimator and other control circuitry' block. The output of the 'Subtractor' goes to a 'Non-linear processor' block. The output of the 'Non-linear processor' is S_out. The 'Receive path' contains the R_in signal. The 'Echo estimator and other control circuitry' block receives inputs from both the 'Send path' and the 'Receive path'. Various gain and loss parameters are labeled: A_ECHO (between Hybrid and S_in), A_CANC (between Subtractor and Non-linear processor), A_NLP (between Non-linear processor and S_out), L_RES (between Subtractor and Non-linear processor), L_RET (between Non-linear processor and S_out), and L_RIN (between R_in and the receive path). A label T1513670-93/d04 is at the bottom right.](0236eff05bcb8f3a343ea7933aaa306b_img.jpg) + +Block diagram of an echo canceller. A 'Hybrid' block on the left has a 'Near end' input and two output ports: S\_in and R\_out. The S\_in port is the input to the 'Send path' (indicated by a dashed line). The R\_out port is the input to the 'Receive path' (indicated by a dashed line). Inside the 'Send path', the signal from S\_in goes to a 'Subtractor' block. The 'Subtractor' also receives an input from an 'Echo estimator and other control circuitry' block. The output of the 'Subtractor' goes to a 'Non-linear processor' block. The output of the 'Non-linear processor' is S\_out. The 'Receive path' contains the R\_in signal. The 'Echo estimator and other control circuitry' block receives inputs from both the 'Send path' and the 'Receive path'. Various gain and loss parameters are labeled: A\_ECHO (between Hybrid and S\_in), A\_CANC (between Subtractor and Non-linear processor), A\_NLP (between Non-linear processor and S\_out), L\_RES (between Subtractor and Non-linear processor), L\_RET (between Non-linear processor and S\_out), and L\_RIN (between R\_in and the receive path). A label T1513670-93/d04 is at the bottom right. + +FIGURE 4/G.165 + +#### Echo canceller + +### 2.2 echo loss ( $A_{ECHO}$ ) + +*F: affaiblissement d'écho ( $A_{ECHO}$ )* + +*S: atenuación del eco ( $A_{ECHO}$ )* + +The attenuation of a signal from the receive-out port ( $R_{out}$ ) to the send-in port ( $S_{in}$ ) of an echo canceller, due to transmission and hybrid loss, i.e. the loss in the (near-end) echo path. + +NOTE – This definition does not strictly adhere to the echo loss definition given in 2.2/G.122 which applies to loss of the *a-t-b* path viewed from the virtual switching point of the international circuit. The echo canceller may be located closer to the echo reflection point. + +### 2.3 pure delay ( $t_r$ ) + +*F: retard pur ( $t_r$ )* + +*S: retardo puro ( $t_r$ )* + +The delay from the $R_{out}$ port to the $S_{in}$ port due to the delays inherent in the (near end) echo path transmission facilities. In this case, the transit time directly across the hybrid is assumed to be zero. + +1) These definitions assume that non linearities are not present in the (near-end) echo path and that the signal at $S_{in}$ is purely echo. + +### 2.4 (near-end) echo path or end delay ( $t_d$ ) + +*F: retard de trajet d'écho (proche), ou retard d'extrémité ( $t_d$ )* + +*S: retardo de trayecto de eco (cercano); o retardo de extremo ( $t_d$ )* + +The sum of pure delay ( $t_r$ ) and dispersion time is the time required to accommodate the band-limiting, multiple reflection, and hybrid transit effects. This is illustrated in Figure 5. It should be noted that this definition assumes a single echo path. If there are multiple echo paths, the overall echo path delay is the maximum of the individual echo path delays. Since dispersion time varies with different national networks, echo canceller echo path delay capacity is given per this definition. With 8 kHz sampling and an FIR (finite impulse response) version of echo canceller, the number of taps an echo canceller has for a given $t_d$ in msecs is 8 times $t_d$ . + +### 2.5 cancellation ( $A_{CANC}$ ) + +*F: annulation ( $A_{CANC}$ )* + +*S: compensación; cancelación ( $A_{CANC}$ )* + +The attenuation of the echo signal as it passes through the send path of an echo canceller. This definition specifically excludes any nonlinear processing on the output of the canceller to provide for further attenuation. + +### 2.6 residual echo level ( $L_{RES}$ ) + +*F: niveau d'écho résiduel ( $L_{RES}$ )* + +*S: nivel de eco residual ( $L_{RES}$ )* + +The level of the echo signal which remains at the send-out port of an operating echo canceller after imperfect cancellation of the circuit echo. It is related to the receive-in signal $L_{Rin}$ by + +$$L_{RES} = L_{Rin} - A_{ECHO} - A_{CANC}$$ + +Any nonlinear processing is not included. + +### 2.7 nonlinear processor (NLP) + +*F: processeur non linéaire (NLP)* + +*S: procesador no lineal (NLP)* + +A device having a defined suppression threshold level and in which: + +- signals having a level detected as being below the threshold are suppressed, and +- signals having a level detected as being above the threshold are passed although the signal may be distorted. + +#### NOTES + +- The precise operation of a nonlinear processor depends upon the detection and control algorithm used. +- An example of a nonlinear processor is an analogue centre clipper in which all signal levels below a defined threshold are forced to some minimum value. + +### 2.8 nonlinear processing loss ( $A_{NLP}$ ) + +*F: affaiblissement par traitement non linéaire ( $A_{NLP}$ )* + +*S: atenuación por procesamiento (o tratamiento) no lineal ( $A_{NLP}$ )* + +Additional attenuation of residual echo level by a nonlinear processor placed in the send path of an echo canceller. + +NOTE – Strictly, the attenuation of a nonlinear process cannot be characterized by a loss in dB. However, for purposes of illustration and discussion of echo canceller operation, the careful use of $A_{NLP}$ is helpful. + +### 2.9 returned echo level ( $L_{\text{RET}}$ ) + +*F: niveau de retour d'écho ( $L_{\text{RET}}$ )* + +*S: nivel del eco devuelto ( $L_{\text{RET}}$ )* + +The level of the signal at the send-out port of an operating echo canceller which will be returned to the talker. The attenuation of a nonlinear processor is included, if one is normally present. $L_{\text{RET}}$ is related to $L_{\text{Rin}}$ by + +$$L_{\text{RET}} = L_{\text{Rin}} - (A_{\text{ECHO}} + A_{\text{CANC}} + A_{\text{NLP}})$$ + +If nonlinear processing is not present, note that $L_{\text{RES}} = L_{\text{RET}}$ . + +### 2.10 combined loss ( $A_{\text{COM}}$ ) + +*F: affaiblissement combiné ( $A_{\text{COM}}$ )* + +*S: atenuación combinada ( $A_{\text{COM}}$ )* + +The sum of echo loss, cancellation loss and nonlinear processing loss (if present). This loss relates $L_{\text{Rin}}$ to $L_{\text{RET}}$ by: + +$$L_{\text{RET}} = L_{\text{Rin}} - A_{\text{COM}}, \text{ where } A_{\text{COM}} = A_{\text{ECHO}} + A_{\text{CANC}} + A_{\text{NLP}}$$ + +### 2.11 convergence + +*F: convergence* + +*S: convergencia* + +The process of developing a model of the echo path which will be used in the echo estimator to produce the estimate of the circuit echo. + +### 2.12 convergence time + +*F: temps de convergence* + +*S: tiempo de convergencia* + +For a defined echo path, the interval between the instant a defined test signal is applied to the receive-in port of an echo canceller with the estimated echo path impulse response initially set to zero, and the instant the returned echo level at the send-out port reaches a defined level. + +### 2.13 leak time + +*F: temps de fuite* + +*S: tiempo de fuga* + +The interval between the instant a test signal is removed from the receive-in port of a fully-converged echo canceller and the instant the echo path model in the echo canceller changes such that, when a test signal is reapplied to $R_{\text{in}}$ with the convergence circuitry inhibited, the returned echo is at a defined level. + +This definition refers to echo cancellers employing, for example, leaky integrators in the convergence circuitry. + +## 3 Characteristics of echo cancellers + +## 3.1 General + +This Recommendation is applicable to the design of echo cancellers. The echo cancellers are assumed to be “half” echo cancellers, i.e. those in which cancellation takes place only in the send path due to signals present in the receive path. + +## 3.2 Purpose, operation and environment + +Echo, in any 2-wire or combination 2- and 4-wire telephone circuit, is caused by impedance mismatches. An echo canceller can be used to reduce this echo to tolerable levels. + +The echo present at the send-in port of an echo canceller is a distorted and delayed replica of the incoming speech from the far end, i.e. the echo is the incoming speech as modified by the echo path. The echo path is commonly described by its impulse response (see Figure 5). This response of a typical echo path shows a pure delay $t_p$ , due to the delays inherent in the echo path transmission facilities, and a dispersed signal due to band limiting and multiple reflections. The sum of these is the echo path delay, $t_d$ . The values of delay and dispersion will vary depending on the properties of the echo paths, e.g. they may vary for different national networks. Note that the echo path can still include more than one source of echo; many network configurations exist in which multiple 2-wire to 4-wire conversions exist in the end path of an echo canceller. + +It is assumed that the echo paths are basically linear and not continuously varying2), e.g. have no phase roll (see Recommendation G.164). The performance of the echo canceller is critically dependent on the linearity of the echo path between $R_{out}$ and $S_{in}$ (see Figure 4). A signal with peak clipping, presented at $R_{in}$ , will cause minimal degradation in canceller performance. This is because the identical peak clipped signal is presented to both the echo estimator and the real echo path. If peak clipping occurs in either only the branch to the echo estimator or only in the real echo path, the difference in the two signals will cause the canceller performance to degrade. This is because the linear processing used in the canceller cannot develop a model to accurately represent the non-linearity introduced by peak clipping. + +The echo path may include both analogue and digital links. The digital links introduce a peak clipping level defined in Recommendation G.711 as the level of the peak of a +3.1 dBm0 sine wave. Application of the clipping level to the $R_{in}$ signal prior to the location of the internal branch point to the echo estimator will minimize the degradation of canceller performance for high level signals. + +In addition, the loss of the echo path in dB (see 2.2) is likely to be such that the minimum loss from $R_{out}$ to $S_{in}$ of the echo canceller will be equal to the difference between relative levels at these two ports plus 6 dB. Echo cancellers designed to this Recommendation will perform properly for echo loss ( $A_{ECHO}$ ) of 6 dB or greater. For ( $A_{ECHO}$ ) less than 6 dB they may still work but with degraded performance. It is not possible to quantify this degraded performance. + +An echo canceller must be able to synthesize a replica of the echo path impulse response. Many echo cancellers model the echo path using a sampled data representation, the sampling being at the Nyquist rate (8000 Hz). Such an echo canceller, to function properly, must have sufficient storage capacity for the required number of samples3). Typically, too few storage locations will prevent adequate synthesis of all echo paths: too many storage locations will create undesirable additional noise due to the unused locations which, because of estimation noise, are generally not zero. It should be recognized that an echo canceller introduces an additional parallel echo path. If the impulse response of the echo path model is sufficiently different from the echo path impulse response, the total returned echo may be larger than that due to the echo path only. + +The echo paths change as the echo canceller is used in successive connections. When speech first arrives at $R_{in}$ , the echo canceller must adapt or converge to the new echo path, and it is desirable that this be fairly rapid, e.g. about one-half second. Also the residual echo should be small regardless of the level of the receive speech and the characteristics of the echo path. Some Administrations feel that a slightly higher residual echo level may be permitted provided it is further reduced using a small amount of nonlinear processing (see 5). + +2) Echo cancellers designed specifically for echo paths which are nonlinear and/or time variant are likely to be much more complex than those not so designed. It is felt that insufficient information exists to include such echo cancellers in this Recommendation. Echo cancellers conforming to this Recommendation are adaptive and will cope with slowly varying echo paths when only a receive signal is present. + +3) Echo cancellers having storage capacities of 8 ms to 64 ms have been successfully demonstrated. Maximum echo path delay $t_d$ , in the network in which the canceller will be used will determine the required storage capacity. + +![Figure 5/G.165: Example of an impulse response of an echo path. The graph shows a signal h(t) on the vertical axis against time on the horizontal axis. The signal starts at a constant level, then drops sharply to a negative peak, rises to a positive peak, and then oscillates with decreasing amplitude. Two time intervals are marked: t_r (echo return time) from the start of the drop to the start of the first peak, and t_d (echo delay) from the start of the drop to the start of the final oscillations. The label T1513680-93/d05 is at the bottom right.](d48475a25698b1c0592e4cfe07138f2a_img.jpg) + +Figure 5/G.165: Example of an impulse response of an echo path. The graph shows a signal h(t) on the vertical axis against time on the horizontal axis. The signal starts at a constant level, then drops sharply to a negative peak, rises to a positive peak, and then oscillates with decreasing amplitude. Two time intervals are marked: t\_r (echo return time) from the start of the drop to the start of the first peak, and t\_d (echo delay) from the start of the drop to the start of the final oscillations. The label T1513680-93/d05 is at the bottom right. + +FIGURE 5/G.165 +**Example of an impulse response of an echo path** + +When there is receive speech and the near party begins to double talk, an echo canceller may interpret the transmit signal as a new echo signal and attempt to adapt to it. This can seriously degrade the subjective quality of the connection. Not only is the echo cancellation reduced but distortion of the double talking speech may occur as the echo canceller dynamically attempts to adapt. Two common approaches are taken as a solution. The first is to use an algorithm which causes slow adaptation during periods of double talk. The second is to employ a double talk detector, similar to that used in echo suppressors. The echo canceller double talk detector, however, generally should favour break-in at the expense of false operation on echo. This differs from the double talk detector in an echo suppressor. + +Thus, echo cancellers have the following fundamental requirements: + +- 1) rapid convergence; +- 2) subjective low returned echo level during single talk; +- 3) low divergence during double talk. + +Echo cancellers may remain active for several non-voice signals as well, in particular, Group 3 facsimile. As noted in 1.3, tests for adequate performance are required but not defined. Test 10, in 3.4.2.10, will eventually address this gap. + +It is increasingly common to have echo cancellers operate in tandem, especially in cellular applications. Tests for adequate performance are not defined. Test 11, in 3.4.2.11, is under study for this purpose. + +When echo cancellers are located on the subscriber side of the international signalling equipment, signalling tones do not pass through the cancellers so no special action is necessary. When cancellers are on the international side of the signalling equipment they are normally disabled by the switch during the active signalling exchange intervals in order to prevent distortion of the signalling tones by the echo canceller. When signalling tones simultaneously appear at the canceller receive and send ports (double talk) the receive signal will be processed through the echo path model contained in the canceller. The signal estimate produced by the canceller may sufficiently distort the send side signal so that it will not be properly recognized by the signalling receive unit (Note 1). + +An echo canceller must be disabled during the transmission of the CCITT No. 6 and No. 7 continuity check tone (Note 2). If an echo canceller conforming to this Recommendation is located on the international side of a circuit with CCITT No. 6 or No. 7 signalling and is not externally disabled by the switch, it will not corrupt the return of the continuity check tone only if it is able to pass the optional tests No. 6 and No. 7 of this Recommendation. Similarly, if an echo canceller conforming to this Recommendation is located on the international side of CCITT No. 5 signalling units and is not disabled by the switch, it will not corrupt the continuously compelled line signalling exchange only if it is able to pass the optional tests No. 6 and No. 7 of this Recommendation. + +#### NOTES + +1 For some echo cancellers this problem may not occur when the send and receive frequencies are different. + +2 Recommendation Q.271 on CCITT No. 6 and Recommendation Q.724 on CCITT No. 7 both include the following statement: "As the presence of active echo suppressors in the circuit would interfere with the continuity check, it is necessary to disable the suppressors during the check and to re-enable them, if required, after the check has been completed." + +## 3.3 External enabling/disabling + +An interface should be included in Type A and D echo cancellers to provide for enabling or disabling by an externally derived ground (earth) from the trunk circuit and controlled by the associated switch or ISC. The enabler should function to permit or prevent normal echo canceller operation. Certain Type C echo cancellers may be disabled directly by a digital signal. Type C echo cancellers should provide 64 kbit/s bit sequence integrity (i.e. if integrated, the A-law/ $\mu$ -law conversion will also be disabled) in the externally disabled state. + +## 3.4 Tests and requirements for performance with inputs signals applied to the send and receive paths + +### 3.4.1 Transmission performance + +The appropriate transmission performance requirements of Recommendation G.164 also apply to echo cancellers except as noted below. + +#### 3.4.1.1 Delay distortion – Type A + +The delay distortion relative to the minimum delay shall not exceed the values given in Table 1. + +TABLE 1/G.165 + +| Frequency band (Hz) | Delay distortion ( $\mu\text{s}$ ) | +|---------------------|------------------------------------| +| 500-600 | 300 | +| 600-1000 | 150 | +| 1000-2600 | 50 | +| 2600-3000 | 250 | + +#### 3.4.1.2 Attenuation distortion – Type A + +The attenuation distortion shall be such that if $Q$ dB is the attenuation at 800 Hz (or 1000 Hz) the attenuation shall be within the range $(Q + 0.5)$ dB to $(Q - 0.2)$ dB at any frequency in the band 300 - 3400 Hz and at 200 Hz, within the range of $(Q + 1.0)$ dB to $(Q - 0.2)$ dB. + +#### 3.4.1.3 Group delay – Type C + +The group delay in the send path should be kept to a minimum and should not exceed 1 ms. No significant delay should occur in the receive path. + +NOTE – The creation of frame slips in the echo path can lead to an occasional degradation of the echo cancellation. If a delay is necessary to synchronize the digital send and receive paths, the global admissible delay on the send path, including the group delay mentioned above, must not exceed 1 ms and on the receive path 250 $\mu\text{s}$ . + +#### 3.4.1.4 Group delay – Type D + +The group delay in the send and receive paths shall meet the requirements of 3.4.1.3 for Type C echo cancellers with the addition of the delay allowed for codecs as given in Recommendation G.712. + +#### 3.4.1.5 Overload – Type A and Type D + +The insertion loss of a 1004 Hz sine wave shall not increase by more than 0.1 dB for levels from 0 to +3.1 dBm0. For signals at $R_{in}$ whose peaks are greater than the peaks of a +3.1 dBm0 sine wave, the peak signals at $R_{out}$ shall remain unchanged as the $R_{in}$ signal is increased above +3.1 dBm0. In a similar manner the peak signal at the echo estimator input, for a +3.1 dBm0 sine wave at $R_{in}$ , shall remain unchanged as the $R_{in}$ signal is increased above +3.1 dBm0. + +#### 3.4.2 Echo canceller performance + +The performance requirements which follow are for echo cancellers which include nonlinear processors (see Annex A for echo cancellers which do not include a nonlinear processor). + +In the tests, it is assumed that the nonlinear processor can be disabled, that the echo path impulse response store (H register) can be cleared (set to zero) and that adaptation can be inhibited. + +The requirements are described in terms of tests made by applying signals to $R_{in}$ and $S_{in}$ of an echo canceller, and measuring the $S_{out}$ signals. The test set-up is as shown in Figure 6. The ports are assumed to be at equal relative level points. Band-limited noise is used as the receive input test signal. The echo loss is independent of frequency. + +![Block diagram of the test set-up for echo canceller performance. A central 'Echo canceller' block has three control inputs at the bottom: 'S and H register to zero', 'Inhibit convergence', and 'Disable non-linear processing'. On the left, 'S_in' enters the canceller from a 'Summer' block. The 'Summer' receives input from a 'Noise generator N' (via a switch) and an 'Echo loss' block. The 'Echo loss' block is fed by an 'Echo delay' block, which receives signal from the 'R_out' port of the canceller. On the right, 'S_out' goes to a 'Detector'. The 'R_in' port receives signal from another 'Noise generator' via a switch. Labeled T1513690-93/d06.](4636adff5682a064f0ae5f13a1d464a6_img.jpg) + +``` + +graph LR + N1[Noise generator N +(see Note)] -- switch --- Summer + Summer -- S_in --- EC[Echo canceller] + EC -- S_out --- Detector + EC -- R_out --- ED[Echo delay] + ED --- EL[Echo loss] + EL --- Summer + N2[Noise generator +(see Note)] -- switch --- EC + EC -- R_in --- N2 + SH[S and H register +to zero] --> EC + IC[Inhibit +convergence] --> EC + DNP[Disable +non-linear +processing] --> EC + +``` + +Block diagram of the test set-up for echo canceller performance. A central 'Echo canceller' block has three control inputs at the bottom: 'S and H register to zero', 'Inhibit convergence', and 'Disable non-linear processing'. On the left, 'S\_in' enters the canceller from a 'Summer' block. The 'Summer' receives input from a 'Noise generator N' (via a switch) and an 'Echo loss' block. The 'Echo loss' block is fed by an 'Echo delay' block, which receives signal from the 'R\_out' port of the canceller. On the right, 'S\_out' goes to a 'Detector'. The 'R\_in' port receives signal from another 'Noise generator' via a switch. Labeled T1513690-93/d06. + +NOTE – The requirements in 3.4.2 are based on the use of band-limited white noise (300-3400 Hz) as the test signal. Noise shaped in accordance with Recommendation G.227 may also be used. However, the applicability of the requirements in 3.4.2 requires confirmation and is under study. + +The use of alternative test signals more representative of real speech and possible changes in test procedures and requirements are also under study. + +FIGURE 6/G.165 +**Test for echo canceller performance** + +The primary purpose of an echo canceller is to control the echo of a speech signal. This is done by synthesizing a replica of the echo path impulse response and using it to generate an estimate of the echo which is subtracted from the actual circuit echo. The synthesis must be accomplished using a speech input signal. Because of the difficulty of defining a speech test signal, the following tests are type tests and rely upon the use of a band-limited noise test signal primarily for measurement convenience and repeatability. These tests should be performed on an echo canceller only after the design has been shown to properly synthesize a replica of the echo path impulse response from a speech input signal and its corresponding echo. Speech signals are not used in the tests in this subclause. Additionally, the nonlinear processor in the echo canceller should be designed to minimize and potentially avoid the perceptible effects of double-talk clipping and background noise contrast (see test 9 described later in this Recommendation). Tests to ensure proper operation are under study. + +#### 3.4.2.1 Test No. 1 – Steady state residual and returned echo level test + +This test is meant to ensure that the steady state cancellation ( $A_{CANC}$ ) is sufficient to produce a residual echo level which is sufficiently low to permit the use of nonlinear processing without undue reliance on it. + +The H register is initially cleared and a receive signal is applied for a sufficient time for the canceller to converge producing a steady state residual echo level. + +##### Requirement (provisional) + +With the H register initially set to zero, the nonlinear processor disabled for all values of receive input signal level such that $L_{Rin} \geq -30$ dBm0 and $\leq 0$ dBm0 and for all values of echo loss $\geq 6$ dB and echo path delay, $t_d \leq \Delta$ ms4), the residual echo level should be less than or equal to that shown in Figure 7. (Extension of the mask for $L_{Rin}$ values between $-10$ dBm0 and $0$ dBm0 under study) . When the nonlinear processor is enabled, the returned echo level must be less than $-65$ dBm0 for all values of $L_{Rin}$ between $-30$ and $0$ dBm0. + +NOTE – Recommendation G.113 allows for up to 5 PCM codecs in the echo path. Meeting the requirement of Figure 7 under those conditions has not been verified. This is under study. + +![Figure 7/G.165: A graph showing the residual echo level (L_RES) in dBm0 versus the receive input signal level (L_Rin) in dBm0. The x-axis (L_Rin) has major ticks at -30, -20, and -10 dBm0. The y-axis (L_RES) has major ticks at -50, -48, -45, -40, -36, and -35 dBm0. A solid black line defines the upper limit of the allowed residual echo level, starting at (-30, -48) and ending at (-10, -36). A shaded gray region exists above this line, indicating the prohibited zone. The graph area is a grid. Reference code T1513700-93/d07 is in the bottom right.](89dcb02be40d2949bb93de93bbf213d5_img.jpg) + +| $L_{Rin}$ (dBm0) | $L_{RES}$ (dBm0) | +|------------------|------------------| +| -30 | -48 | +| -10 | -36 | + +Figure 7/G.165: A graph showing the residual echo level (L\_RES) in dBm0 versus the receive input signal level (L\_Rin) in dBm0. The x-axis (L\_Rin) has major ticks at -30, -20, and -10 dBm0. The y-axis (L\_RES) has major ticks at -50, -48, -45, -40, -36, and -35 dBm0. A solid black line defines the upper limit of the allowed residual echo level, starting at (-30, -48) and ending at (-10, -36). A shaded gray region exists above this line, indicating the prohibited zone. The graph area is a grid. Reference code T1513700-93/d07 is in the bottom right. + +FIGURE 7/G.165 + +4) Different echo cancellers may be designed to work satisfactorily for different echo path delays depending on their application in various networks. Thus $\Delta$ , whenever it appears in this Recommendation, represents the echo path delay, $t_d$ , for which the echo canceller is designed. + +#### 3.4.2.2 Test No. 2 – Convergence test + +This test is meant to ensure that the echo canceller converges rapidly for all combinations of input signal levels and echo paths and that the returned echo level is sufficiently low. The H register is initially cleared and adaption is inhibited. The double talk detector, if present, is put in the double talk mode by applying signals to $S_{in}$ and $R_{in}$ . The signal at $S_{in}$ is removed and simultaneously adaption is enabled. The degree of adaption, as measured by the returned echo level, will depend on the convergence characteristics of the echo canceller and the double talk detection hangover time. + +The test procedure is to clear the H register and inhibit adaption. Signal N is applied at a level $-10$ dBm0 and a signal is applied at $R_{in}$ . Then N is removed and simultaneously adaption is enabled (see Figure 8). After 500 ms inhibit adaption and measure the returned echo level. The nonlinear processor should be enabled. + +![Timing diagram for Test No. 2. The diagram shows three horizontal lines representing signals over time. The top line is labeled R_in and has a dashed horizontal line at level 0. The middle line is labeled N and also has a dashed horizontal line at level 0. The bottom line is labeled Adaption and has two levels: 'Inhibit' and 'Enable'. The Adaption line starts at the 'Inhibit' level, drops to the 'Enable' level at the same time the N signal starts, and then returns to the 'Inhibit' level 500 ms later. An arrow points to the 'Inhibit' level after 500 ms with the text 'Measure combined loss'. A label 'T1513710-93/d08' is at the bottom right of the diagram.](0a8d173734e4e46c344178e8d21bcbc3_img.jpg) + +Timing diagram for Test No. 2. The diagram shows three horizontal lines representing signals over time. The top line is labeled R\_in and has a dashed horizontal line at level 0. The middle line is labeled N and also has a dashed horizontal line at level 0. The bottom line is labeled Adaption and has two levels: 'Inhibit' and 'Enable'. The Adaption line starts at the 'Inhibit' level, drops to the 'Enable' level at the same time the N signal starts, and then returns to the 'Inhibit' level 500 ms later. An arrow points to the 'Inhibit' level after 500 ms with the text 'Measure combined loss'. A label 'T1513710-93/d08' is at the bottom right of the diagram. + +FIGURE 8/G.165 + +##### Requirement + +With the H register initially set to zero, for all values $L_{R_{in}} \geq -30$ dBm0 and $\leq 0$ dBm0 and present for 500 ms and for all values of echo loss $\geq 6$ dB and echo path delay, $t_d \leq \Delta$ ms, the combined loss ( $A_{COM} = A_{ECHO} + A_{CANC} + A_{NLP}$ ) should be $\geq 27$ dB. + +#### 3.4.2.3 Test No. 3 – Performance under conditions of double talk + +The two parts of this test are meant to test the performance of the canceller under various conditions of double talk. The tests make the assumption that, upon detection of double talk, measures are taken to prevent or slow adaption in order to avoid excessive reduction in cancellation. + +**3.4.2.3.1** Test No. 3a is meant to ensure that the double talk detection is not so sensitive that echo and low level near-end speech falsely cause operation of the double talk detector to the extent that adaption does not occur. The test procedure is to clear the H register; then for some value of echo delay and echo loss, a signal is applied to $R_{in}$ . Simultaneously (see Figure 9) an interfering signal which is sufficiently low in level to not seriously hamper the ability of the echo canceller to converge, is applied at $S_{in}$ . This signal should not cause the double talk detector to be activated, and adaption and cancellation should occur. After 1 s the adaption is inhibited and the residual echo measured. The nonlinear process should be *disabled*. + +![Timing diagram for Figure 9/G.165 showing signal levels Rin, N, and Adaption over time. Rin is a constant high level. N starts at 0, steps up to a level below Rin, and then returns to 0. A 1-second duration is marked from the start of the N signal step until it returns to 0. The Adaption signal has 'Inhibit' and 'Enable' lines. It is initially 'Enable', then steps to 'Inhibit' at the start of the N signal step, and returns to 'Enable' when N returns to 0. An arrow labeled 'Measure residual echo level' points to the 'Enable' line after it returns to 'Enable'. The diagram is labeled T1513720-93/d09.](ad29805cd4f64ad2828e14feb66de664_img.jpg) + +Timing diagram for Figure 9/G.165 showing signal levels Rin, N, and Adaption over time. Rin is a constant high level. N starts at 0, steps up to a level below Rin, and then returns to 0. A 1-second duration is marked from the start of the N signal step until it returns to 0. The Adaption signal has 'Inhibit' and 'Enable' lines. It is initially 'Enable', then steps to 'Inhibit' at the start of the N signal step, and returns to 'Enable' when N returns to 0. An arrow labeled 'Measure residual echo level' points to the 'Enable' line after it returns to 'Enable'. The diagram is labeled T1513720-93/d09. + +FIGURE 9/G.165 + +##### Requirement + +With the H register initially set to zero for all values of $L_{Rin} \geq -25$ dBm0 and $\leq -10$ dBm0, $N = L_{Rin} - 15$ dB, $A_{ECHO} \geq 6$ dB and echo path delay, $t_d \leq \Delta$ ms, convergence should occur within 1.0 s and $L_{RES}$ should be $\leq N$ . + +**3.4.2.3.2** Test No. 3b is meant to ensure that the double talk detector is sufficiently sensitive and operates fast enough to prevent large divergence during double talking. + +The test procedure is to fully converge the echo canceller for a given echo path. A signal is then applied to $R_{in}$ . Simultaneously (see Figure 10) a signal $N$ is applied to $S_{in}$ which has a level at least that of $R_{in}$ . This should cause the double talk detector to operate. After any arbitrary time, $\delta t > 0$ , the adaption is inhibited and the residual echo measured. The nonlinear processor should be *disabled*. + +![Timing diagram for Figure 10/G.165 showing signal levels Rin, N, and Adaption over time. Rin is a constant high level. N starts at 0, steps up to a level at least that of Rin, and then returns to 0. The Adaption signal has 'Inhibit' and 'Enable' lines. It is initially 'Enable', then steps to 'Inhibit' at the start of the N signal step. After an arbitrary time delta t > 0, it returns to 'Enable' when N returns to 0. An arrow labeled 'Measure residual echo level' points to the 'Enable' line after it returns to 'Enable'. The diagram is labeled T1513730-93/d10.](011fecb4a85637472f0c697a6cbdb15d_img.jpg) + +Timing diagram for Figure 10/G.165 showing signal levels Rin, N, and Adaption over time. Rin is a constant high level. N starts at 0, steps up to a level at least that of Rin, and then returns to 0. The Adaption signal has 'Inhibit' and 'Enable' lines. It is initially 'Enable', then steps to 'Inhibit' at the start of the N signal step. After an arbitrary time delta t > 0, it returns to 'Enable' when N returns to 0. An arrow labeled 'Measure residual echo level' points to the 'Enable' line after it returns to 'Enable'. The diagram is labeled T1513730-93/d10. + +FIGURE 10/G.165 + +##### Requirement + +With the echo canceller initially in the fully converged state for all values of $L_{Rin} \geq -30$ dBm0 and $\leq -10$ dBm0, and for all values of $N \geq L_{Rin}$ and for all values of echo loss $\geq 6$ dB and echo path delay $t_d \leq \Delta$ ms, the residual echo level after the simultaneous application of $L_{Rin}$ and $N$ for any time period should not increase more than 10 dB over the steady state requirements of Test No. 1. + +#### 3.4.2.4 Test No. 4 – Leak rate test + +This test is meant to ensure that the leak time is not too fast, i.e. that the contents of the H register do not go to zero too rapidly. + +The test procedure is to fully converge the echo canceller for a given echo path and then to remove all signals from the echo canceller. After two minutes the contents of the H register are frozen, a signal applied to $R_{in}$ and the residual echo measured (see Figure 11). The nonlinear process is used in normal operation, it should be *disabled*. + +![Timing diagram for residual echo measurement. The diagram shows four horizontal lines representing signals over time. 1. Rin: A signal that is present initially, then drops to zero at the start of the 2-minute period, and returns to a high level after the 2-minute period. 2. N: A constant zero signal. 3. Adaption: A signal with 'Inhibit' and 'Enable' states. It is 'Enable' during the initial convergence and the 2-minute period, and switches to 'Inhibit' after the 2-minute period. 4. A measurement point is indicated by an arrow labeled 'Measure residual echo level' at the beginning of the 'Inhibit' state. A horizontal double-headed arrow between the start and end of the 'Enable' state is labeled '2 min'. The diagram is labeled T1513740-93/d11.](af06598cfb31b517e79b50d74f72a0ca_img.jpg) + +Timing diagram for residual echo measurement. The diagram shows four horizontal lines representing signals over time. 1. Rin: A signal that is present initially, then drops to zero at the start of the 2-minute period, and returns to a high level after the 2-minute period. 2. N: A constant zero signal. 3. Adaption: A signal with 'Inhibit' and 'Enable' states. It is 'Enable' during the initial convergence and the 2-minute period, and switches to 'Inhibit' after the 2-minute period. 4. A measurement point is indicated by an arrow labeled 'Measure residual echo level' at the beginning of the 'Inhibit' state. A horizontal double-headed arrow between the start and end of the 'Enable' state is labeled '2 min'. The diagram is labeled T1513740-93/d11. + +FIGURE 11/G.165 + +##### Requirement + +With the echo canceller initially in the fully converged state for all values of $L_{Rin} \geq -30$ dBm0 and $\leq -10$ dBm0, two minutes after the removal of the $R_{in}$ signal, the residual echo level should not increase more than 10 dB over the steady state requirement of Test No. 1. + +#### 3.4.2.5 Test No. 5 – Infinite return loss convergence test + +This test is meant to ensure that the echo canceller has some means to prevent the unwanted generation of echo. This may occur when the H register contains an echo path model, either from a previous connection or the current connection, and the echo path is opened (circuit echo vanishes) while a signal is present at $R_{in}$ . + +The test procedure is to fully converge the echo canceller for a given echo path. The echo path is then interrupted while a signal is applied to $R_{in}$ . 500 ms after interrupting the echo path the returned echo signal at $S_{out}$ should be measured (see Figure 12). The nonlinear processor should be *disabled*. + +![Timing diagram for infinite return loss convergence test. The diagram shows four horizontal lines representing signals over time. 1. Rin: A signal that is 'Present' initially. 2. Echo path: A signal that is 'Open' initially and then drops to zero. 3. Sout: A signal that shows a sharp peak at the moment the echo path opens, followed by an exponential decay. A horizontal double-headed arrow from the start of the decay to a measurement point is labeled '500 ms'. 4. Adaption: A signal with 'Inhibit' and 'Enable' states. It is 'Enable' during the initial convergence and switches to 'Inhibit' when the echo path opens. A measurement point is indicated by an arrow labeled 'Measure returned echo level' at the 500 ms mark. The diagram is labeled T1513750-93/d12.](67518cfe156890dac13b5e67abd10dc1_img.jpg) + +Timing diagram for infinite return loss convergence test. The diagram shows four horizontal lines representing signals over time. 1. Rin: A signal that is 'Present' initially. 2. Echo path: A signal that is 'Open' initially and then drops to zero. 3. Sout: A signal that shows a sharp peak at the moment the echo path opens, followed by an exponential decay. A horizontal double-headed arrow from the start of the decay to a measurement point is labeled '500 ms'. 4. Adaption: A signal with 'Inhibit' and 'Enable' states. It is 'Enable' during the initial convergence and switches to 'Inhibit' when the echo path opens. A measurement point is indicated by an arrow labeled 'Measure returned echo level' at the 500 ms mark. The diagram is labeled T1513750-93/d12. + +FIGURE 12/G.165 + +##### Requirement (provisional) + +With the echo canceller initially in the fully converged state for all values of echo loss $\geq 6$ dB, and for all values of $L_{\text{Rin}} \geq -30$ dBm0 and $\leq -10$ dBm0, the returned echo level at $S_{\text{out}}$ , 500 ms after the echo path is interrupted, should be $\leq -37$ dBm0. + +#### 3.4.2.6 Test No. 6 – Nondivergence on narrow-band signals (optional) + +This test has the object of verifying that the echo canceller will stay stable for narrow-band signals. The residual echo level is measured before and after the application of a sinusoidal wave or a wave composed of two frequencies. + +The method consists of completely converging the echo canceller as in Test No. 1. A mono or bifrequency signal is then applied to $R_{\text{in}}$ . After three minutes the adaptation is inhibited and the returned echo is measured. The nonlinear processor is disabled for this test. + +##### Requirement + +With the echo canceller first fully converged as in Test No. 1 and then after application at $R_{\text{in}}$ for three minutes of a mono or bifrequency signal ( $f_1 + f_2$ with $|f_1 - f_2| \geq 170$ Hz) such that $L_{\text{Rin}} \geq -30$ dBm0 and $\leq -10$ dBm0 and for all values of echo return loss $\geq 6$ dB and echo path delay $t_d \leq$ tail path capacity, the residual echo level should be less than or equal to that shown in Figure 7. + +#### 3.4.2.7 Test No. 7 – Nonconvergence of echo cancellers on mono or bifrequency signals transmitted in a handshaking protocol (optional) + +Echo cancellers which are not externally disabled, and which are located on the line side of Signalling System No. 5, 6 and 7 in international exchanges or are associated with national exchanges, must operate properly with signalling tones. This test is meant to ensure that echo cancellers will not dump a mono or bifrequency signal transmitted in a handshaking protocol on the transmit direction either before receiving or after receiving an identical signal (except for level and phase) on the receive direction. This is intended to allow correct transmission of certain types of signalling tones without externally disabling echo cancellers. + +##### Requirement + +With the echo canceller initially in any convergence state (for simplification, the fully converged state for an echo return loss of 6 dB may be chosen), the level of a mono or bifrequency signal ( $f_1 + f_2$ with $|f_1 - f_2| \geq 170$ Hz) applied at the send in port within 90 msecs (either before or after) of having applied the same signal (except for level and phase) at the receive in port, should not vary by more than 2 dB when compared to the nominal level of the injected signal. The level " $N$ " of each frequency applied is such that the peak level of the mono or bifrequency signal should be in the range $-18$ dBm0 $\leq N \leq 3$ dBm0 and the echo return loss is infinite for the bulk of the test. + +#### 3.4.2.8 Test No. 8 – Overload test for Type A and Type D cancellers + +NOTE – The numbers enclosed by [ ] are provisional and under study. + +This test is meant to ensure that the peak clipping level of the echo estimating path as well as the transmission paths $R_{\text{in}}$ to $R_{\text{out}}$ and $S_{\text{in}}$ to $S_{\text{out}}$ are consistent with the peak clipping levels of Recommendation G.711 in order to minimize degradation of the canceller's performance for high level signals. + +The test procedure is to first independently test the send and receive paths and the echo estimating path. + +##### 3.4.2.8.1 Send and receive paths + +The send and receive paths are tested by observing that signals less than [+3.05 dBm0] do not exhibit peak clipping and that signals greater than [+3.25 dBm0] do exhibit peak clipping. Measurements are made on a 1004 Hz test tone with a distortion analyser for signal levels beginning at 0 dBm0 which are gradually increased in level until the clipping level is reached. + +###### Requirement + +The clipping level is defined as the level at which the total distortion is found to increase by [1 dB] with respect to the total distortion measured for a 1004 Hz tone at 0 dBm0. The clipping level shall fall within the range [+3.15 $\pm$ 0.1 dBm0]. + +##### 3.4.2.8.2 Echo estimating path + +The echo estimating path is tested by developing a model of a known echo path, disabling adaptation, disabling the nonlinear processor, opening the echo path, applying a test tone to $R_{in}$ and measuring the distortion on the signal at $S_{out}$ . + +For an echo path, having a flat frequency response over the voice band, with a 6 dB echo loss, converge the echo canceller using a $[-10 \text{ dBm}0 \text{ (noise/artificial speech)}]$ signal applied to $R_{in}$ for at least 3 seconds. Then disable the adaptation, disconnect the echo path and disable the nonlinear processor. Apply a 1004 Hz test tone at 0 dBm0 and measure the total distortion at $S_{out}$ . Gradually increase the level of the test tone at $R_{in}$ until peak clipping is observed as indicated by an increase in the distortion measured at $S_{out}$ . + +###### Requirement + +The clipping level is defined as the level at which the total distortion is found to increase by [1 dB] with respect to the total distortion measured for a 1004 Hz tone at 0 dBm0. The clipping level shall fall within the range $[+3.15 \pm 0.1 \text{ dBm}0]$ . + +#### 3.4.2.9 Test No. 9 – Comfort noise test (provisional, all values under study) + +##### 3.4.2.9.1 Part 1 (matching) + +- 1) Set $N$ to $-60 \text{ dBm}0$ to $-40 \text{ dBm}0$ . +- 2) Set $L_{Rin}$ to silence ( $< -40 \text{ dBm}0$ ) and hold for $x$ minutes ( $x$ under study). +- 3) Set $L_{Rin}$ to $-10 \text{ dBm}0$ and set the echo loss to 8 dB. +- 4) Measure $L_{Sout}$ . + +###### Requirement + +$L_{Sout}$ shall be within $y$ dB of $N$ ( $y$ under study, recommended value is 0.5 dB to 2.0 dB). Also, this value shall hold as long as noise level $N$ remains constant. + +##### 3.4.2.9.2 Part 2 (adjustment down) + +- 1) Lower $N$ by 10 dB. +- 2) Measure $L_{Sout}$ within 2 seconds. + +###### Requirement + +$L_{Sout}$ shall be within $y$ dB of $N$ ( $y$ under study, recommended value is 0.5 dB to 2.0 dB) or, if $N < -60 \text{ dBm}0$ , $L_{Sout}$ shall also be $< -60 \text{ dBm}0$ . + +##### 3.4.2.9.3 Part 3 (adjustment up) + +- 1) Raise $N$ by 10 dB. +- 2) Measure $L_{Sout}$ within $z$ seconds ( $z$ under study, recommended value is greater than 2 seconds). + +###### Requirement + +$L_{Sout}$ shall be within $y$ dB of $N$ ( $y$ under study, recommended value is 0.5 dB to 2.0 dB) or, if $N < -60 \text{ dBm}0$ , $L_{Sout}$ shall also be $< -60 \text{ dBm}0$ . + +#### 3.4.2.10 Test No. 10 – Facsimile test + +Under study. + +#### 3.4.2.11 Test No. 11 – Tandem echo canceller test + +Under study. + +## 4 Characteristics of an echo canceller tone disabler + +### 4.1 General + +The echo cancellers covered by this Recommendation shall be equipped with a tone detector that conforms to this subclause. This tone detector responds to a disabling signal which is different from that used to disable the echo suppressor as described in 5/G.164 and consists of a 2100 Hz tone with periodic phase reversals inserted in that tone. The tone disabler should respond only to the specified in-band signal. It should not respond to other in-band signals, e.g. speech, or a 2100 Hz tone without a phase reversal. The tone disabler should detect and respond to a disabling signal which may be present in either the send or the receive path. + +The requirements for echo canceller disabling to ensure proper operation with ATME No. 2 equipment that transmits the 2100 Hz tone with phase reversals could be met by using either the tone disabler specified in this subclause, or the echo suppressor tone disabler specified in 5/G.164. However, use of the 5/G.164 disabler does not assure proper operation with all currently specified V-Series modems. + +The term disabled in this subclause refers to a condition in which the echo canceller is configured in such a way as to no longer modify the signals which pass through it in either direction. Under this condition, no echo estimate is subtracted from the send path, the nonlinear processor is made transparent, and the delay through the echo canceller still meets the conditions specified in 3.4.1. However, no relationship between the circuit conditions before and after disabling should be assumed. For one thing, the operation of echo cancellers with tonal inputs (such as the disabling tone) is unspecified. Additionally, the impulse response stored in the echo canceller prior to convergence (and prior to the disabling tone being sent) is arbitrary. This can lead to apparent additional echo paths which, in some echo canceller implementations, remain unchanged until the disabling tone is recognized. Also note that echo suppressors could be on the same circuit and there is no specified relationship between their delay in the enabled and disabled states. In spite of the above, it is possible, for example, to measure the round-trip delay of a circuit with the disabling tone but the trailing edge of the tone burst should be used and sufficient time for all devices to be disabled should be allotted before terminating the disabling tone and starting the timing. + +It should be noted that this condition does not necessarily fulfil the requirements for 64 kbit/s bit sequence integrity, for which case other means of disabling in line with 3.4 will apply. + +A reference tone disabler is described in Annex B. + +### 4.2 Disabler characteristics + +The echo canceller tone disabler requires the detection of a 2100 Hz tone with phase reversals of that tone. The characteristics of the transmitted signal are defined in Recommendation V.25. Phase variations in the range of $180^\circ \pm 25^\circ$ must be detected while those in the range of $0^\circ \pm 110^\circ$ must not be detected. + +The frequency characteristics of the tone detector are the same as the characteristics of the echo suppressor tone detector given in 5.2/G.164. + +The dynamic range of this detector should be consistent with the input levels as specified in Recommendations V.2 and H.51 with allowances for variation introduced by the public switched telephone network. + +### 4.3 Guardband characteristics + +Similar to that defined in 5.3/G.164, consistent with the dynamic range given in 4.2 with the following exception. The detector should operate perfectly with white noise less than or equal to 11 dB below the level of the 2100 Hz signal. No definitive guidelines can be given for the range between 5 and 11 dB because of the variations in the test equipment used. In particular, performance may vary with the peak-to-average ratio of the noise generator used. As a general guideline, however, the percentage of correct operation (detection of phase variations of $180^\circ \pm 25^\circ$ and non-detection of phase variations of $0^\circ \pm 110^\circ$ ) should fall by no more than 1% for each dB reduction in signal-to-noise below 11 dB. The Administration of the Federal Republic of Germany mentions the possibility of designing a detector capable of operating perfectly at 5 dB signal-to-noise ratio. + +### **4.4 Holding-band characteristics** + +Same as defined in 5.4/G.164. + +### **4.5 Operate time** + +The operate time must be sufficiently long to provide immunity from false operation due to voice signals, but not so long as to needlessly extend the time to disable. The tone disabler is required to operate within one second of the receipt of the disabling signal. + +### **4.6 False operation due to speech currents** + +Same as in 5.6/G.164. + +### **4.7 False operation due to data signals** + +It is desirable that the tone disabler should rarely operate falsely on data signals from data sets that would be adversely affected by disabling of the echo canceller. To this end, a reasonable objective is that, for an echo canceller installed on a working circuit, usual data signals from such data sets should not, on the average, cause more than 10 false operations during 100 hours of data transmissions. + +### **4.8 Release time** + +Same as in 5.7/G.164. + +## **4.9 Other considerations** + +Both the echo of the disabling tone and the echo of the calling tone may disturb the detection of the echo canceller disabling tone. As such, it is not recommended to add the receive and transmit signal inputs together to form an input to a single detector. + +Careful attention should be given to the number of phase reversals required for detection of the disabling tone. Some Administrations favour relying on 1 to improve the probability of detection even in the presence of slips, impulse noise, and low signal-to-noise ratio. Other Administrations favour relying on 2 to improve the probability of correctly distinguishing between non-phase-reversed and phase-reversed 2100 Hz tones. + +## **5 Nonlinear processors for use in echo cancellers** + +## **5.1 Scope** + +For the purpose of this Recommendation the term “nonlinear processor” is intended to mean only those devices which fall within the definition given in 2.5 and which have been proven to be effective in echo cancellers. It is possible to implement such nonlinear processors in a number of ways (centre clippers being just one example), with fixed or adaptive operating features, but no recommendation is made for any particular implementation. General principles and guidelines are given in 5.2. More detailed and concrete information requires reference to specific implementations. This is done in Annex C for the particular case of a “reference nonlinear processor”. The use of this term denotes an implementation given for guidance and illustration only. It does not exclude other implementations nor does it imply that the reference nonlinear processor is necessarily the most appropriate realization on any technical, operational or economic grounds. + +## 5.2 General principles and guidelines + +### 5.2.1 Function + +#### 5.2.1.1 General + +The nonlinear processor is located in the send path between the output of the subtractor and the send-out port of the echo canceller. Conceptually, it is a device which blocks low level signals and passes high level signals. Its function is to further reduce the residual echo level ( $L_{RES}$ as defined in 2.4) which remains after imperfect cancellation of the circuit echo so that the necessary low returned echo level ( $L_{RET}$ as defined in 2.7) can be achieved. + +#### 5.2.1.2 Network performance + +Imperfect cancellation can occur because echo cancellers which conform to this Recommendation may not be capable of adequately modelling echo paths which generate significant levels of nonlinear distortion (see 3.2). Such distortion can occur, for example, in networks conforming to Recommendation G.113 in which up to five pairs of PCM codecs (conforming to Recommendation G.712) are permitted in an echo path. The accumulated quantization distortion from these codecs may prevent an echo canceller from achieving the necessary $L_{RET}$ by using linear cancellation techniques alone. It is therefore recommended that all echo cancellers capable only of modelling the linear components of echo paths but intended for general network use should incorporate suitable nonlinear processors. + +#### 5.2.1.3 Limitations + +This use of nonlinear processors represents a compromise in the circuit transparency which would be possible by an echo canceller which could achieve the necessary $L_{RET}$ by using only modelling and cancellation techniques. Ideally, the nonlinear processor should not cause distortion of near-end speech. In practical devices it may not be possible to sufficiently approach this ideal. In this case it is recommended that nonlinear processors should not be active under double-talk or near-end single-talk conditions. From this it follows that excessive dependence must not be placed on the nonlinear processor and that $L_{RES}$ must be low enough to prevent objectionable echo under double-talk conditions. + +#### 5.2.1.4 Data transmission + +Nonlinear processors may affect the transmission of data through an enabled echo canceller. This is under study. + +### 5.2.2 Suppression threshold + +#### 5.2.2.1 General + +The suppression threshold level ( $T_{SUP}$ ) of a nonlinear processor is expressed in dBm0 and is equal to the highest level of a sine-wave signal at a given moment that is just suppressed. Either fixed or adaptive suppression threshold levels may be used. + +#### 5.2.2.2 Fixed suppression threshold + +With a fixed suppression threshold level, the appropriate level to use will depend upon the cancellation achieved and the statistics of speech levels and line conditions found in the particular network in which the echo canceller is to be used. It is therefore recommended that the actual level should be field selectable to permit the user to adjust it for the actual network environment. Values of fixed suppression threshold levels to be used are under study – see Notes 1 and 2. + +###### NOTES + +1 As an interim guide, it is suggested that the suppression threshold level should be set a few decibels above the level that would result in the *peaks* of $L_{RES}$ for a “ $2\sigma$ -talker” and a “ $2\sigma$ -echo return loss” being suppressed. + +2 Results of a field trial reported by one Administration indicated that a fixed suppression threshold level of $-36$ dBm0 gave a satisfactory performance. A theoretical study, by another Administration, of an echo path containing five pairs of PCM codecs showed that for an $L_{Rin}$ of $-10$ dBm0, the quantization noise could result in an $L_{RES}$ of $-38$ dBm0. + +#### 5.2.2.3 Adaptive suppression threshold + +A good compromise can be made between using a high $T_{SUP}$ to prevent it being exceeded by loud talker residual echo and using a low $T_{SUP}$ to reduce speech distortion on break-in by making $T_{SUP}$ adaptive to the actual circuit conditions and speech levels. This may be achieved in a number of ways and no recommendation is made for any particular implementation. General guidelines applicable to the control algorithm and suppression threshold levels are under study. + +### 5.2.3 Control of nonlinear processor activation + +#### 5.2.3.1 General + +To conform to the recommendation made in 5.2.1.3, it is necessary to control the activation of the nonlinear processor so that it is not active when near-end speech is likely to be present. When “active”, the nonlinear processor should function as intended to reduce $L_{RES}$ . When “inactive”, it should not perform any nonlinear processing on any signal passing through the echo canceller. + +#### 5.2.3.2 Control guidelines + +It is recommended that the following two guidelines should govern control of the activation of a nonlinear processor. First, because they are intended to further reduce $L_{RES}$ , they should be active when $L_{RES}$ is at a significant level. Second, because they should not distort near-end speech, they should be inactive when near-end speech is present. Where these two guidelines conflict the control function should favour the second. + +#### 5.2.3.3 Static characteristics + +A conceptual diagram showing the two operational states of a nonlinear processor is shown in Figure 13. The $L_{S_{in}}$ $L_{R_{in}}$ plane is divided into two regions, W and Z by the threshold $WZ$ ( $T_{WZ}$ ). In the W region the nonlinear processor is inactive while in the Z region it is active. Proper control of the nonlinear processor to ensure operation in the appropriate region requires recognition of the double-talk condition or the presence of near-end speech. Imperfect detection of double-talk combined with a high suppression threshold level will result in distortion of near-end speech. The echo canceller then exhibits some of the characteristics of an echo suppressor. A low suppression level will permit easy double-talking, even if a detection error is made because the near-end speech will suffer only a low level of nonlinear distortion. If the suppression threshold level is too low, then peaks of residual echo may be heard. + +![Figure 13/G.165: Nonlinear processor operating regions. A graph showing the relationship between the level of signal at the send-in port (L_Sin) and the level of signal at the receive-in port (L_Rin). The graph is divided into two regions, W and Z, by a diagonal threshold line labeled T_WZ. Region W is the area above the line where the nonlinear processor is inactive. Region Z is the area below the line where the nonlinear processor is active. Four numbered circles (1, 2, 3, 4) illustrate different signal states: 1 is in region Z, 2 is in region W, 3 is in region Z, and 4 is on the threshold line. Arrows indicate transitions between these states. The axes are labeled dBm0.](2b6886fb185564eb8b6ff86d856a672a_img.jpg) + +The figure is a conceptual diagram of nonlinear processor operating regions. The vertical axis represents the 'Level of signal at send-in port $L_{S_{in}}$ ' in dBm0. The horizontal axis represents the 'Level of signal at receive-in port $L_{R_{in}}$ ' in dBm0. A diagonal line labeled $T_{WZ}$ separates two regions: 'W' (Nonlinear processor inactive) above the line and 'Z' (Nonlinear processor active) below the line. Four numbered circles (1, 2, 3, 4) are shown: 1 is in region Z, 2 is in region W, 3 is in region Z, and 4 is on the threshold line. Arrows indicate transitions between these states: 1 to 2, 2 to 4, 4 to 3, and 3 to 1. The text 'T1513760-93/d13' is present in the bottom right corner of the graph area. + +Figure 13/G.165: Nonlinear processor operating regions. A graph showing the relationship between the level of signal at the send-in port (L\_Sin) and the level of signal at the receive-in port (L\_Rin). The graph is divided into two regions, W and Z, by a diagonal threshold line labeled T\_WZ. Region W is the area above the line where the nonlinear processor is inactive. Region Z is the area below the line where the nonlinear processor is active. Four numbered circles (1, 2, 3, 4) illustrate different signal states: 1 is in region Z, 2 is in region W, 3 is in region Z, and 4 is on the threshold line. Arrows indicate transitions between these states. The axes are labeled dBm0. + +FIGURE 13/G.165 +Nonlinear processor operating regions + +#### 5.2.3.4 Dynamic characteristics + +The dynamic characteristics can be specified by stating the time that elapses when the signal conditions pass from a point in one area to a point in the other area before the state appropriate to the second area is established. Four such transitions are shown by arrows in Figure 13. + +##### Transition No. 1 – W to Z, $L_{\text{Sin}}$ constant, $L_{\text{Rin}}$ increasing + +In this case the $L_{\text{Sin}}$ signal occurred first and the $L_{\text{Rin}}$ is increasing to a sufficiently high level to override the $L_{\text{Sin}}$ signal in the control path and cause the nonlinear processor to change from the inactive to the active state. Since this will cause distortion of the $L_{\text{Sin}}$ signal (near talker speech in this case) the action should not be initiated too quickly. + +##### Transition No. 2 – Z to W, $L_{\text{Sin}}$ constant, $L_{\text{Rin}}$ decreasing + +In this case the $L_{\text{Rin}}$ signal has overridden the $L_{\text{Sin}}$ signal in the control path and the nonlinear processor is in the active state. The $L_{\text{Rin}}$ signal is now decreasing. The nonlinear processor should remain in the active state sufficiently long to prevent echo, which is stored in the echo path, from being near by the far talker. + +##### Transition No. 3 – Z to W, $L_{\text{Rin}}$ constant, $L_{\text{Sin}}$ increasing + +This transition is replicating the onset of double-talk. As soon as possible after the $L_{\text{Sin}}$ signal is detected the nonlinear processor should be switched to the inactive state in order to minimize any distortion of the near talker speech. + +##### Transition No. 4 – W to Z, $L_{\text{Rin}}$ constant, $L_{\text{Sin}}$ decreasing + +In this case $L_{\text{Sin}}$ has been recognized but is decreasing. Any action which is taken should favour continuing to permit the $L_{\text{Sin}}$ signal to pass. This implies there should be some delay in switching the nonlinear processor back to the active state. + +### 5.2.4 Frequency limits of control paths + +Under study. + +NOTE – Depending on the particular implementation of the nonlinear processor, the considerations and frequency response limits given in 3.2.4.2/G.164 for the suppression and break-in control paths of echo suppressors may also be applicable to similar control paths used in nonlinear processors. These control paths may include the activation control and adaptive suppression threshold level control. + +### 5.2.5 Signal attenuation below threshold level + +The attenuation of signals having a level below that of the suppression threshold level of a nonlinear processor in the active state must be such that the requirements of 3.4.2.1 are met. + +### 5.2.6 Testing of nonlinear processors + +The nonlinear processor may be considered as a special case of an echo suppressor which is limited to suppressing only low level signals. The types of test required to determine the nonlinear processor performance characteristics are very similar to the echo suppressor tests given in Recommendation G.164. However, depending on the specific implementation of a nonlinear processor, the transitions between areas W and Z of Figure 13 may not be as sharply defined as is the case for echo suppressors. Signals observed at the send-out port of the echo canceller may be distorted for short periods when transitions between the W and Z operating regions occur. Although Recommendation G.164 may be used as a guide to the testing of nonlinear processors, it may be necessary to introduce unique test circuit modifications in order to make measurements on some specific nonlinear processor implementations. No recommendation can be given for a universal test circuit appropriate for all nonlinear processor implementations. + +# Annex A + +## Echo cancellers without nonlinear processing + +(This annex forms an integral part of this Recommendation) + +It may be possible to implement echo cancellers without the inclusion of nonlinear processing. For these echo cancellers the total echo loss is provided by echo cancellation. The achievable echo cancellation is limited by the characteristics of the echo path and by the method of implementing the echo canceller. In particular, if one pair of codecs conforming to Recommendation G.712 is used in the echo path or in the echo canceller, the maximum echo cancellation (considering quantizing errors in the echo canceller and other impairments) is that shown by the solid line in Figure A.1. + +Echo cancellers conforming to the solid line in Figure A.1 have been tested and found to provide acceptable performance in Japan. Other tests, however, suggest that the echo cancellation required in echo cancellers for general application is at least that shown by the broken line in Figure A.1. Further study is needed. Pending the results of that study, echo cancellers which do not include nonlinear processors are not yet recommended for general application. + +All the provisions and tests in the body of this Recommendation apply to these echo cancellers except as follows: + +- a) Subclause 3.4.2.1: The residual echo level requirement is that shown by the solid line of Figure A.1. +- b) For all other tests, any reference to nonlinear processing should be ignored. + +![Figure A.1/G.165: A graph showing the residual echo level requirement (L_RES) versus the input echo level (L_Rin). The x-axis (L_Rin) ranges from -40 to -10 dBm0. The y-axis (L_RES) ranges from 45 to 70 dBm0. A solid line represents the requirement, which is flat at 65 dBm0 for L_Rin from -40 to -32 dBm0, then increases linearly to 46 dBm0 at L_Rin = -10 dBm0. A dashed line represents an alternative requirement, which is flat at 65 dBm0 for L_Rin from -40 to -21 dBm0, then increases linearly to 54 dBm0 at L_Rin = -10 dBm0. Shaded regions indicate the tolerance bands around these lines.](cd31d0e7e4b524e074808154dd279205_img.jpg) + +The graph plots the residual echo level requirement ( $L_{RES}$ ) in dBm0 on the y-axis against the input echo level ( $L_{Rin}$ ) in dBm0 on the x-axis. The x-axis ranges from -40 to -10 dBm0 with major ticks at -40, -32, -30, -21, -20, and -10. The y-axis ranges from 45 to 70 dBm0 with major ticks at 45, 46, 54, 57, 65, and 70. A solid line represents the requirement, which is flat at 65 dBm0 for $L_{Rin}$ from -40 to -32 dBm0, then increases linearly to 46 dBm0 at $L_{Rin} = -10$ dBm0. A dashed line represents an alternative requirement, which is flat at 65 dBm0 for $L_{Rin}$ from -40 to -21 dBm0, then increases linearly to 54 dBm0 at $L_{Rin} = -10$ dBm0. Shaded regions indicate the tolerance bands around these lines. + +| $L_{Rin}$ (dBm0) | $L_{RES}$ (dBm0) - Solid Line | $L_{RES}$ (dBm0) - Dashed Line | +|------------------|-------------------------------|--------------------------------| +| -40 | 65 | 65 | +| -32 | 65 | 65 | +| -21 | 57 | 65 | +| -10 | 46 | 54 | + +T1513770-93/d14 + +Figure A.1/G.165: A graph showing the residual echo level requirement (L\_RES) versus the input echo level (L\_Rin). The x-axis (L\_Rin) ranges from -40 to -10 dBm0. The y-axis (L\_RES) ranges from 45 to 70 dBm0. A solid line represents the requirement, which is flat at 65 dBm0 for L\_Rin from -40 to -32 dBm0, then increases linearly to 46 dBm0 at L\_Rin = -10 dBm0. A dashed line represents an alternative requirement, which is flat at 65 dBm0 for L\_Rin from -40 to -21 dBm0, then increases linearly to 54 dBm0 at L\_Rin = -10 dBm0. Shaded regions indicate the tolerance bands around these lines. + +FIGURE A.1/G.165 + +# Annex B + +## Description of an echo canceller reference tone disabler + +(This annex forms an integral part of this Recommendation) + +## B.1 General + +This annex describes the characteristics of an echo canceller reference tone disabler. The use of the term reference denotes a disabling implementation given for guidance only. It does not exclude alternative implementations of a tone disabler which responds to the signal as defined in Recommendation V.25, and which also meets all of the criteria for reliability of operation and protection from false operation by speech signals. + +## B.2 Disabler characteristics + +The echo canceller reference tone disabler described in this annex detects a 2100 Hz tone with periodic phase reversals which occur every $450 \pm 25$ ms. The characteristics of the transmitted signal are defined in Recommendation V.25. + +### B.2.1 Tone detection + +The frequency characteristics of the tone detector used in this reference tone disabler are the same as the characteristics of the echo suppressor tone detector given in 5.2/G.164, except that the upper limit of the dynamic range is $-6$ dBm0. + +### B.2.2 Phase reversal detection + +The reference tone disabler responds to a signal which contains phase reversals of $108^\circ \pm 10^\circ$ at its source (as specified in Recommendation V.25) when this signal has been modified by allowable degradations caused by the network, e.g. noise, phase jitter, etc. This disabler is insensitive to phase jitter of $\pm 15^\circ$ peak-to-peak in the frequency range of 0 - 120 Hz. This accommodates to the phase jitter permitted by Recommendations H.12 and G.229. In order to minimize the probability of false disabling of the echo canceller due to speech currents and network-induced phase changes, this reference tone disabler does not respond to single phase changes of the 2100 Hz tone in the range $0^\circ \pm 110^\circ$ occurring in a one second period. This number has been chosen since it represents the approximate phase shift caused by a single frame slips in a PCM system. + +## B.3 Guardband characteristics + +Meets requirements in 5.3/G.164. + +NOTE – The possibility of interference during the phase reversal detection period has been taken into account. One potential source of interference is the presence of calling tone as specified in Recommendation V.25. If the calling tone interferes with the detection of the phase reversal, the entire disabling detection sequence is restarted, but only one time. Recommendation V.25 ensures at least one second of quiet time between calling tone burst. + +## B.4 Holding-band characteristics + +Meets requirements in 5.4/G.164. + +## B.5 Operate time + +The reference tone disabler operates within one second of the receipt, without interference, of the sustained 2100 Hz tone with periodic phase reversals, having the level in the range $-6$ to $-31$ dBm0. The one second operate time permits the detection of the 2100 Hz tone and ensures that two phase reversals will occur (unless a slip or impulse noise masks one of the phase reversals). + +## B.6 False operation due to speech currents + +Meets requirements in 5.6/G.164. + +## B.7 False operation due to data signals + +Meets the requirement in 4.7. To this end, the tone disabler circuitry becomes inoperative if one second of clear (i.e. no phase reversals or other interference) 2100 Hz tone is detected. The detected circuit remains inoperative during the data transmission and only becomes operative again $250 \pm 150$ ms after a signal in the holding band falls at least 3 dB below the maximum holding sensitivity. Thus the possibility of inadvertent disabling of the echo canceller during data transmission is minimized. + +## B.8 Release time + +Meets requirements in 5.7/G.164. + +# Annex C + +## Description of a reference nonlinear processor + +(This annex forms an integral part of this Recommendation) + +## C.1 General + +This annex, which is for the purposes of illustration only and not intended as a detailed design (see 5.1), describes a reference nonlinear processor based upon concepts that are as simple as possible but having included in it a sufficient number of features to give guidance for a wide range of possible implementations. To this end two variants of the reference nonlinear processor are included. Both are based on a centre clipper having either of the idealized transfer functions illustrated in Figure C.1. The suppression threshold level (determined, in this case by the clipping level) in the first variant is adaptive, adaptation being by reference to $L_{\text{Rin}}$ . Activation control is by reference to the difference between $L_{\text{Rin}}$ and $L_{\text{Sin}}$ . In the second variant the suppression threshold is fixed. It is assumed that the reference nonlinear processor is used in an echo canceller which can achieve a cancellation of the linear components of any returned echo of at least $N$ dB. The value of $N$ is under study. + +![Figure C.1/G.165: Two examples of idealized centre clipper transfer functions. The figure contains two subplots, (a) and (b), each showing a graph of Output (O/P) versus Input (I/P). Both graphs show a piecewise linear function that is zero for a range of input values around the origin and then increases linearly. In subplot (a), the zero-output region is wider. In subplot (b), the zero-output region is narrower. A horizontal double-headed arrow labeled 'Clipping level' spans the zero-output region in both plots, indicating the range of input values for which the output is zero. The text 'T1513780-93/d15' is present in subplot (b).](155bd5ec49c26532be9f04b06904002e_img.jpg) + +Figure C.1/G.165: Two examples of idealized centre clipper transfer functions. The figure contains two subplots, (a) and (b), each showing a graph of Output (O/P) versus Input (I/P). Both graphs show a piecewise linear function that is zero for a range of input values around the origin and then increases linearly. In subplot (a), the zero-output region is wider. In subplot (b), the zero-output region is narrower. A horizontal double-headed arrow labeled 'Clipping level' spans the zero-output region in both plots, indicating the range of input values for which the output is zero. The text 'T1513780-93/d15' is present in subplot (b). + +FIGURE C.1/G.165 +Two examples of idealized centre clipper transfer functions + +## C.2 Suppression threshold ( $T_{\text{SUP}}$ ) + +Adaptive $T_{\text{SUP}} = (L_{\text{Rin}} - x \pm 3)$ dBm0 for $-30 \leq L_{\text{Rin}} \leq -10$ dBm0 + +Fixed $T_{\text{SUP}} = x'$ dBm0 + +NOTE – Values of $x$ and $x'$ are under study. Values of 18 for $x$ and $-36$ for $x'$ have been suggested but confirmation is required that these values are appropriate for use in all networks. + +## C.3 Static characteristics of activation control + +$T_{\text{WZ}} = (L_{\text{Rin}} - y \pm 3)$ dBm0 for $-30 \leq L_{\text{Rin}} \leq -10$ dBm0 + +NOTES + +1 $T_{\text{WZ}}$ is as defined in 5.2.3.3. + +2 The value of $y$ may be different for each variant, and this is under study. Values of $x$ dB in the case of the adaptive $T_{\text{SUP}}$ and $\geq 6$ dB for $y$ in the case of the fixed $T_{\text{SUP}}$ seem reasonable. + +## C.4 Dynamic characteristics of activation control + +Dynamic characteristics of the activation control are given in Tables C.1 and C.2. Also see Figure 13. + +## C.5 Frequency limits of control paths + +See Recommendation 5.2.4. + +## C.6 Testing + +Tables C.1 and C.2 indicate, by reference to Recommendation G.164, how the dynamic performance of nonlinear processor activation control may be checked using sine wave signals. Figures C.2 and C.3 show the traces obtained on an oscilloscope for these tests. + +![Timing diagram showing input (Sin) and output (Sout) signals for NLP operate and hangover times.](8c5a81acd52538cf9690016966640528_img.jpg) + +The figure shows two timing traces, Trace 1 and Trace 2. Trace 1 represents the input signal $S_{\text{in}}$ and Trace 2 represents the output signal $S_{\text{out}}$ . The input signal $S_{\text{in}}$ is a square wave that transitions from a high level to a low level. The output signal $S_{\text{out}}$ is a square wave that transitions from a low level to a high level. The time interval between the falling edge of $S_{\text{in}}$ and the rising edge of $S_{\text{out}}$ is labeled $t_d$ . The time interval from the rising edge of $S_{\text{out}}$ to the falling edge of $S_{\text{in}}$ is labeled $\alpha$ . The time interval from the falling edge of $S_{\text{in}}$ to the falling edge of $S_{\text{out}}$ is labeled $\beta$ . The diagram also includes a reference code T1513790-93/d16. + +$\alpha$ Operate time + $\beta$ Hangover time + $t_d$ Time interval in which the distorted signal may be observed + +Timing diagram showing input (Sin) and output (Sout) signals for NLP operate and hangover times. + +FIGURE C.2/G.165 +Traces for NLP operate and hangover times, $L_{\text{Rin}}$ constant + +![Timing diagram showing two traces, Trace 1 (Rin) and Trace 2 (Sout). Trace 1 is a square wave. Trace 2 shows a distorted signal during the transition of Trace 1. The diagram defines alpha (operate time), beta (hangover time), and td (time interval of distortion) for two transitions.](4cec89a753c447a050c0171c274f2acb_img.jpg) + +The figure is a timing diagram with two horizontal traces. Trace 1, labeled $R_{in}$ , is a square wave that transitions from a high level to a low level and then back to a high level. Trace 2, labeled $S_{out}$ , shows a signal that follows Trace 1 but exhibits distortion during the transitions of Trace 1. Two shaded rectangular regions on Trace 2 highlight these distorted periods. For the first transition (high to low), the time interval from the start of the transition on Trace 1 to the start of the first shaded region is labeled $\alpha$ . The duration of the first shaded region is labeled $\beta$ . The total duration of the first shaded region, from its start to its end, is labeled $t_d$ . A similar shaded region and $t_d$ label are shown for the second transition (low to high). + +Timing diagram showing two traces, Trace 1 (Rin) and Trace 2 (Sout). Trace 1 is a square wave. Trace 2 shows a distorted signal during the transition of Trace 1. The diagram defines alpha (operate time), beta (hangover time), and td (time interval of distortion) for two transitions. + +- $\alpha$ Operate time +- $\beta$ Hangover time +- $t_d$ Time interval in which the distorted signal may be observed + +T1513800-93/d17 + +FIGURE C.3/G.165 + Traces for NLP operate and hangover times, $L_{S_{in}}$ constant + +TABLE C.1/G.165 + +### **Nonlinear processor hangover times** + +| Boundary | | Initial signal | | Final signal | | Recommended value (ms) | Test No. (Rec. G.164) | Excursion (see Fig. 13) | Test circuit, Figure: | Oscilloscope trace | +|----------|----------|------------------------------|---------------------------------|------------------------------|---------------------------------|------------------------|-----------------------|-------------------------|-----------------------|-----------------------------------------------| +| | | Send $L_{\text{Sin}}$ (dBm0) | Receive $L_{\text{Rin}}$ (dBm0) | Send $L_{\text{Sin}}$ (dBm0) | Receive $L_{\text{Rin}}$ (dBm0) | | | | | | +| Z/W | Fixed | -25 | -10 | -25 | -30 | 15-64 | 5 | Transition 2 | 14/G.164 | Trace 1 and trace 2 of Figure C.3 ( $\beta$ ) | +| | Adaptive | -55
-40
-30 | -20
-15
- 5 | -55
-40
-30 | -40
-40
-30 | $\Delta^{\text{a)}}$ | | | | | +| W/Z | Fixed | -15 | -25 | -40 | -25 | 16-120 | 6 | Transition 4 | 17/G.164 | Trace 1 and trace 2 of Figure C.2 ( $\beta$ ) | +| | Adaptive | -40
-40
-25 | -50
-30
-15 | -55
-55
-40 | -50
-30
-15 | 30-50 | | | | | + +a) $\Delta$ is defined in 3.4.2.1 [footnote 4)]. + +TABLE C.2/G.165 + +### **Nonlinear processor operate times** + +| Boundary | | Initial signal | | Final signal | | Recommended value (ms) | Test No. (Rec. G.164) | Excursion (see Fig. 13) | Test circuit, Figure: | Oscilloscope trace | +|----------|----------|------------------------------|---------------------------------|------------------------------|---------------------------------|------------------------|-----------------------|-------------------------|-----------------------|------------------------------------| +| | | Send $L_{\text{Sin}}$ (dBm0) | Receive $L_{\text{Rin}}$ (dBm0) | Send $L_{\text{Sin}}$ (dBm0) | Receive $L_{\text{Rin}}$ (dBm0) | | | | | | +| W/Z | Fixed | -25 | -30 | -25 | -10 | 16-120 | 4 | Transition 1 | 14/G.164 | Trace 2 of Figure C.3 ( $\alpha$ ) | +| | Adaptive | -55
-40
-30 | -40
-40
-30 | -55
-40
-30 | -20
-15
-5 | 15-75 | | | | | +| Z/W | Fixed | -40 | -25 | -15 | -25 | $\leq 1$ | 6 | Transition 3 | 17/G.164 | Trace 2 of Figure C.2 ( $\alpha$ ) | +| | Adaptive | -55
-55
-40 | -50
-30
-15 | -40
-40
-25 | -50
-30
-15 | $\leq 5$ | | | | | \ No newline at end of file diff --git a/marked/G/T-REC-G.212-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.212-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..85764c9ef27c76cd508b554d0ba00dd5360456eb --- /dev/null +++ b/marked/G/T-REC-G.212-198811-I_PDF-E/raw.md @@ -0,0 +1,125 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' in a bold, sans-serif font. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.212** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**INTERNATIONAL ANALOGUE CARRIER SYSTEMS +GENERAL CHARACTERISTICS COMMON TO ALL +ANALOGUE CARRIER-TRANSMISSION SYSTEMS** + +--- + +**HYPOTHETICAL REFERENCE CIRCUITS FOR +ANALOGUE SYSTEMS** + +**ITU-T Recommendation G.212** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.212 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## **HYPOTHETICAL REFERENCE CIRCUITS FOR ANALOGUE SYSTEMS** + +## **GENERAL DEFINITIONS** + +### **1 hypothetical reference circuit** + +*F: circuit fictif de référence* + +*S: circuito ficticio de referencia* + +This is a hypothetical circuit of defined length and with a specified number of terminal and intermediate equipments, this number being sufficient but not excessive. It forms a basis for the study of certain characteristics of long-distance circuits (noise, for example). + +### **2 hypothetical reference circuit for telephony** + +*F: circuit fictif de référence pour la téléphonie* + +*S: circuito ficticio de referencia para la telefonía* + +This is a complete telephone circuit (between audio-frequency terminals) established on a hypothetical international telephone carrier system and having a specified length and a specified number of modulations and demodulations of channels, groups, supergroups, these numbers being reasonably great but not having their maximum possible values. The hypothetical reference circuit has to reflect what is generally expected to be the practical application of the system. + +Various hypothetical reference circuits for telephony have been defined to allow the coordination of the different specifications concerning the constituent parts of the multichannel carrier telephone systems, so that the complete telephone circuits set up on these systems can meet CCITT standards. + +In order to take account of the variety of operating conditions and in particular the differences there may be in the size of the countries to be served, the CCITT has defined two categories of hypothetical reference circuits for telephony: + +- a set of hypothetical reference circuits with a length of 2500 km, +- a hypothetical reference circuit with a length of 5000 km (see Recommendation G.215). + +The former includes the following hypothetical reference circuits for telephony: + +- on open-wire lines (see Recommendation G.311), +- on symmetric pair cable (see Recommendation G.322), +- on coaxial pair cable (see Recommendations G.332 to G.346 of sections 3.3 and 3.4). + +The 5000 km hypothetical reference circuit is used in various types of carrier systems on coaxial cable and on radio relay systems. + +The CCIR also has defined the following hypothetical-reference circuits for telephony: + +- 1) In line-of-sight radio-relay systems using frequency-division multiplex, with a capacity of 12 to 60 telephone channels or of more than 60 telephone channels (see Recommendation G.431 or CCIR Recommendations 391 [2] and 392 [3]); +- 2) On tropospheric-scatter radio-relay systems (see CCIR Recommendation 396 [4]); +- 3) For satellite systems (see CCIR Recommendation 352 [5]). + +Each of these various hypothetical reference circuits has the same total length1) and they are all used in the same way. They are only a guide for planning carrier systems. + +These hypothetical reference circuits allow designers to study through connection between different carrier systems at basic groups, supergroups, etc., as discussed in Recommendation G.211. Moreover, when they contain more than one pair of channel modulators and demodulators, they also allow the designers to study an international switched connection having the same total length. + +### 3 homogeneous section + +*F: section homogène* + +*S: sección homogénea* + +A section without diversion or modulation of any channel groups, supergroups, etc., established on the system which is being considered except for those modulations or demodulations defined at the ends of the section. + +All the hypothetical reference circuits defined above consist of homogeneous sections of equal length [6, 9 or 12 sections2) as the case may be]. + +It is assumed that at the end of each homogeneous section, the channels, groups, supergroups, etc., are connected through at random. + +### 4 psophometric power + +*F: puissance psophométrique* + +*S: potencia sofométrica* + +Where square law addition (power addition) of noise can be assumed, it has been found convenient for calculations and design of international circuits to use the idea of psophometric power as defined below: + +$$\text{psophometric power} = \frac{(\text{psophometric voltage})^2}{600}$$ + +or + +$$\text{psophometric power} = \frac{(\text{psophometric e.m.f.})^2}{4 \times 600}$$ + +A convenient unit is the micro-microwatt or picowatt (pW), and this equation can then be given as follows: + +$$\text{psophometric power} = \frac{(\text{psophometric e.m.f. in mV})^2}{0.0024} \text{ (pW)}.$$ + +1) With the exception of the hypothetical reference circuits for satellite systems and for circuits of 5000 km. + +2) The number is not specified for the tropospheric-scatter radio-relay systems. + +## References + +- [1] CCITT Recommendation *4-MHz valve-type systems on standardized 2.6/9.5-mm coaxial cable pairs*, Orange Book, Vol. III-I, Rec. G.338, ITU, Geneva, 1977. +- [2] CCIR Recommendation *Hypothetical reference circuit for radio-relay systems for telephony using frequency-division multiplex with a capacity of 12 to 60 telephone channels*, Vol. IX, Rec. 391, Dubrovnik, 1986. +- [3] CCIR Recommendation *Hypothetical reference circuit for radio-relay systems for telephony using frequency-division multiplex with a capacity of more than 60 telephone channels*, Vol. IX, Rec. 392, Dubrovnik, 1986. +- [4] CCIR Recommendation *Hypothetical reference circuit for trans-horizon radio-relay systems for telephony using frequency-division multiplex*, Vol. IX, Rec. 396, Dubrovnik, 1986. +- [5] CCIR Recommendation *Hypothetical reference circuits for telephony and television in the fixed satellite service*, Vol. IV, Rec. 352, Dubrovnik, 1986. \ No newline at end of file diff --git a/marked/G/T-REC-G.226-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.226-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..232ea330ff9709005d25d75749325d44e475d20e --- /dev/null +++ b/marked/G/T-REC-G.226-198811-I_PDF-E/raw.md @@ -0,0 +1,50 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.226** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS** --- + +### **NOISE ON A REAL LINK** + +**ITU-T Recommendation G.226** + +(Extract from the *Blue Book*) + +--- + +### NOTES + +- 1 ITU-T Recommendation G.226 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +### **NOISE ON A REAL LINK** + +#### **1 Cable systems** + +It should be appreciated that designers are usually concerned, not with particular circuits or links, but with plant that will be used for the establishment of many links. It is not practicable for the CCITT to specify the performance of every real link that may be established, or for the designer to contemplate changing his design to suit the various lengths or other conditions on different real links. The CCITT has therefore defined hypothetical reference circuits, so that designers can be sure that, if their particular design of plant is used throughout a real circuit made up in the same way as a hypothetical reference circuit, the performance specified by the CCITT for the hypothetical reference circuit will be realized on that real circuit. + +A real international link usually has a different make-up from that of the hypothetical reference circuit, and often includes equipments of different design. For each of these two reasons the performance to be expected from real links cannot be deduced uniquely from the Recommendations relative to hypothetical reference circuits. + +However, on a real homogeneous section it must be expected that the noise power measured at the time of commissioning, and with a conventional load as defined in § 2 of Recommendation G.223, will be about the same as that calculated taking into account the particular composition of the real homogeneous section and the real parameters as well as the implications of Recommendation G.222, § 2.6. There should be no cause for anxiety unless the measured noise power exceeds the calculated power by an appreciable amount, which might indicate a fault somewhere in the equipment. In such a case, every effort should be made to reduce the measured noise power to a value of the same order as that calculated. + +#### **2 Radio links** + +See CCIR Recommendation 395 [1]. + +## **Reference** + +- [1] CCIR Recommendation *Noise in the radio portion of circuits to be established over real radio-relay links for FDM telephony*, Vol. IX, Rec. 395, Dubrovnik, 1986. \ No newline at end of file diff --git a/marked/G/T-REC-G.233-198811-I_PDF-E/07b17a620c75522d53916a11e12d1bff_img.jpg b/marked/G/T-REC-G.233-198811-I_PDF-E/07b17a620c75522d53916a11e12d1bff_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..0799408a4eca08eec29bafb288da7dc4a1cf8a0e --- /dev/null +++ b/marked/G/T-REC-G.233-198811-I_PDF-E/07b17a620c75522d53916a11e12d1bff_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:209af8db5266cb38650ae4fdb839f8746e3b5d6453d2968d59d81d36cdfaa66b +size 36484 diff --git a/marked/G/T-REC-G.233-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.233-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.233-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.233-198811-I_PDF-E/5d92d5c9cc01a262b0389d138caa9aea_img.jpg b/marked/G/T-REC-G.233-198811-I_PDF-E/5d92d5c9cc01a262b0389d138caa9aea_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..89f21b613d9914f20ae97a94f9ff5330de7bf791 --- /dev/null +++ b/marked/G/T-REC-G.233-198811-I_PDF-E/5d92d5c9cc01a262b0389d138caa9aea_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:338ae26dcaec33b11dd66e5c1fb875fa2954d005607aa25f88fba415d143bed0 +size 51174 diff --git a/marked/G/T-REC-G.233-198811-I_PDF-E/9ccd03fe518c562a3fe2d3119f50935e_img.jpg b/marked/G/T-REC-G.233-198811-I_PDF-E/9ccd03fe518c562a3fe2d3119f50935e_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..b36d0480129ed07ab06026f90672149c75547a3b --- /dev/null +++ b/marked/G/T-REC-G.233-198811-I_PDF-E/9ccd03fe518c562a3fe2d3119f50935e_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:6df28a3147ddb1a88fc405292d4705764b505cc33eab30d0219ac308f60b74a1 +size 47242 diff --git a/marked/G/T-REC-G.233-198811-I_PDF-E/dd0f5301a5a6dd7c319701302110de88_img.jpg b/marked/G/T-REC-G.233-198811-I_PDF-E/dd0f5301a5a6dd7c319701302110de88_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..10e75b675630c3c0c562d6e8250803025faf46fb --- /dev/null +++ b/marked/G/T-REC-G.233-198811-I_PDF-E/dd0f5301a5a6dd7c319701302110de88_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:1cb3324cab94feb89f9c1c3d7c221de2be3ebf48d3346e5410a04ff8945aa327 +size 44578 diff --git a/marked/G/T-REC-G.233-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.233-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..bbdf16c5ca82d0bb5306f2e2cb616b32287a817c --- /dev/null +++ b/marked/G/T-REC-G.233-198811-I_PDF-E/raw.md @@ -0,0 +1,371 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.233** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER - TRANSMISSION SYSTEMS** --- + +## **RECOMMENDATIONS CONCERNING TRANSLATING EQUIPMENTS** + +**ITU-T Recommendation G.233** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +- 1 ITU-T Recommendation G.233 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## RECOMMENDATIONS CONCERNING TRANSLATING EQUIPMENTS + +(amended at Geneva, 1964; further amended) + +This Recommendation concerns translating equipments with the exception of: + +- channel-translating equipment, in respect of which Recommendations G.232, G.234 [1] and G.235 should be consulted; +- equipment for translation into the line-frequency band; the Recommendations relating to the various line systems should be consulted. + +### 1 Translating procedure + +The procedures whereby the translating equipments defined in Recommendation G.211 translate basic groups, supergroups and mastergroups or a basic 15-supermastergroup assembly (No. 1) are represented by the following figures: + +- 1) Figure 1/G.233 for group-translating equipments (procedures 1 and 2); +- 2) Figure 2/G.233 for supergroup-translating equipments (procedure 1); +- 3) Figure 3/G.233 for mastergroup-translating equipments (procedure 1); +- 4) Figure 4/G.233 for supergroup-translating equipments (procedure 2); +- 5) Figure 5/G.233 for translating equipments for basic 15-supergroup assembly (No. 1) (procedure 2). + +*Note* - Equipments 4 and 5 above are peculiar to procedure 2 described in Recommendation G.211. The conditions in which this procedure is used are described in that Recommendation. + +![Diagram showing the constitution of the basic supergroup. It illustrates five groups (Group No. 1 to 5) with their respective frequency bands and carrier frequencies. The x-axis represents frequency in kHz, ranging from 60 to 552. The y-axis shows the hierarchy of groups. Group 1 is the base group. Groups 2, 3, 4, and 5 are supergroups built on top of the base group. Carrier frequencies are indicated on the right: 420, 468, 516, 564, and 612 kHz. A note on the left refers to Recommendation G.241 for group pilot(s). A note on the right refers to Note in Figure 5/G.233 for carrier frequencies. The diagram is labeled CCITT - 45240.](9ccd03fe518c562a3fe2d3119f50935e_img.jpg) + +Diagram showing the constitution of the basic supergroup. It illustrates five groups (Group No. 1 to 5) with their respective frequency bands and carrier frequencies. The x-axis represents frequency in kHz, ranging from 60 to 552. The y-axis shows the hierarchy of groups. Group 1 is the base group. Groups 2, 3, 4, and 5 are supergroups built on top of the base group. Carrier frequencies are indicated on the right: 420, 468, 516, 564, and 612 kHz. A note on the left refers to Recommendation G.241 for group pilot(s). A note on the right refers to Note in Figure 5/G.233 for carrier frequencies. The diagram is labeled CCITT - 45240. + +FIGURE 1/G.233 +Constitution of the basic supergroup + +![Diagram of the basic mastergroup (FIGURE 2/G.233) showing 5 supergroups. The x-axis represents frequency in kHz with markers at 312, 552, 812, 1052.8, 1300.8, 1556.8, 1796.8, 2044. Carrier frequencies are indicated by arrows pointing to specific points on the frequency axis: 1364, 1612, 1860, 2108, and 2356 kHz. Supergroup No. 4 is shown with its baseband from 812 to 1052.8 kHz. The diagram is labeled CCITT - 45250.](5d92d5c9cc01a262b0389d138caa9aea_img.jpg) + +Supergroup pilot(s) +(see Recommendation G.241) + +Carrier frequencies +(see Note in Figure 5/G.233) + +Supergroup No. 4 + +CCITT - 45250 + +Diagram of the basic mastergroup (FIGURE 2/G.233) showing 5 supergroups. The x-axis represents frequency in kHz with markers at 312, 552, 812, 1052.8, 1300.8, 1556.8, 1796.8, 2044. Carrier frequencies are indicated by arrows pointing to specific points on the frequency axis: 1364, 1612, 1860, 2108, and 2356 kHz. Supergroup No. 4 is shown with its baseband from 812 to 1052.8 kHz. The diagram is labeled CCITT - 45250. + +FIGURE 2/G.233 + +#### **Constitution of the basic mastergroup** + +![Diagram of the basic supermastergroup (FIGURE 3/G.233) showing 3 mastergroups (7, 8, 9). The x-axis represents frequency in kHz with markers at 812, 2044, 8516, 9748.8, 11068.8, 12388. Carrier frequencies are indicated by arrows pointing to specific points on the frequency axis: 10560, 11096, 11880, and 13200 kHz. Mastergroup No. 7 is shown with its baseband from 8516 to 9748.8 kHz. The diagram is labeled CCITT - 45260.](f961cbef0f8217e216b553bed270315b_img.jpg) + +Carrier frequencies +(see Note in Figure 5/G.233) + +Mastergroup No. 7 + +CCITT - 45260 + +Diagram of the basic supermastergroup (FIGURE 3/G.233) showing 3 mastergroups (7, 8, 9). The x-axis represents frequency in kHz with markers at 812, 2044, 8516, 9748.8, 11068.8, 12388. Carrier frequencies are indicated by arrows pointing to specific points on the frequency axis: 10560, 11096, 11880, and 13200 kHz. Mastergroup No. 7 is shown with its baseband from 8516 to 9748.8 kHz. The diagram is labeled CCITT - 45260. + +FIGURE 3/G.233 + +#### **Constitution of the basic supermastergroup** + +![Diagram showing the constitution of the basic 15-supergroup assembly. It plots 15 supergroups (numbered 2 to 16) against frequency in kHz. Each supergroup is represented by a horizontal line with a pilot symbol at its start. The carrier frequencies for each supergroup are indicated by arrows pointing to the right end of each line. The frequencies range from 312 kHz to 4,340 kHz.](de6e8b740c69dac308cce9edfec3eff4_img.jpg) + +Carrier frequencies +(see Note in Figure 5/G.233) + +Supergroup pilot(s) +(see Recommendation G.241) + +| Supergroup No. | Carrier Frequency (kHz) | +|----------------|-------------------------| +| 2 | 312 | +| 3 | 552 | +| 4 | 804 | +| 5 | 1052 | +| 6 | 1300 | +| 7 | 1552 | +| 8 | 1804 | +| 9 | 2052 | +| 10 | 2300 | +| 11 | 2548 | +| 12 | 2796 | +| 13 | 3036 | +| 14 | 3284 | +| 15 | 3532 | +| 16 | 3780 | +| | 4,028 | +| | 4,340 | + +CCITT - 45270 + +Diagram showing the constitution of the basic 15-supergroup assembly. It plots 15 supergroups (numbered 2 to 16) against frequency in kHz. Each supergroup is represented by a horizontal line with a pilot symbol at its start. The carrier frequencies for each supergroup are indicated by arrows pointing to the right end of each line. The frequencies range from 312 kHz to 4,340 kHz. + +FIGURE 4/G.233 + +#### Constitution of the basic 15-supergroup assembly + +![Diagram showing the frequency mapping between Basic 15-supergroup assembly (No. 1) and 15-supergroup assembly (No. 3).](431b8889a0e7f676f0eef40859590349_img.jpg) + +The diagram illustrates the frequency mapping between two 15-supergroup assemblies. On the left, 'Basic 15-supergroup assembly (No. 1)' is shown with supergroup numbers 2 through 16, with a frequency range from 312 kHz to 4028 kHz. A specific frequency of 1552 kHz is marked. On the right, '15-supergroup assembly (No. 3)' is shown with supergroup numbers 16 down to 2, with a frequency range from 8620 kHz to 12336 kHz. A specific frequency of 11096 kHz is marked. Arrows indicate the mapping of supergroups: supergroup 2 in assembly No. 1 maps to supergroup 16 in assembly No. 3, and supergroup 16 in assembly No. 1 maps to supergroup 2 in assembly No. 3. A dashed line at the top right points to a frequency of 12648 kHz, labeled 'Carrier frequency (see Note)'. The text 'CCITT - 45281' is at the bottom right. + +Diagram showing the frequency mapping between Basic 15-supergroup assembly (No. 1) and 15-supergroup assembly (No. 3). + +FIGURE 5/G.233 + +#### Constitution of 15-supergroup assembly No. 3 + +*Note to Figures 1/G.233 to 5/G.233* - The virtual carrier frequencies shown in Figures 1/G.233 to 5/G.233 will normally be the frequencies actually used. However, they are all shown as virtual frequencies to allow for the possibility of using cheaper ways of constituting basic groups, supergroups, etc., in the future. + +### 2 Adjustment of level at basic group-frequency points + +When a group passes through different carrier systems, it is necessary to provide for an adjustment of level: for example, between the limits of about $\pm 4$ dB, wherever the group passes through the basic frequency range. + +### 3 Relative power levels at group distribution frames and supergroup distribution frames + +Although the standardization of the relative power levels at group distribution frames and supergroup distribution frames would be desirable to facilitate the setting-up and maintenance of international carrier systems and routing changes of groups or supergroups from one system to another, it was not possible before the Plenary Assembly of 1972 to recommend such a standardization internationally, because of the diversity of carrier systems already in service. Table 1/G.233 shows, for information, the level used by different Administrations. + +The CCITT concerned itself solely with recommending preferred values for countries which have not yet fixed these values for their national networks. Accordingly: + +- a relative sending level of -36 dBr is recommended at group and supergroup distribution frames; +- for reception, it is recommended that a choice be made between -23 dBr and -30 dBr; +- the following values are recommended for the impedance: + - 150 ohms balanced for group distribution frames, + - 75 ohms unbalanced for supergroup distribution frames. + +TABLE 1/G.233 + +#### **Relative power levels at the basic group and supergroup distribution frames in the carrier systems of various Administrations** + +| Country | | Relative power level at group distribution frame | | Impedance at group distribution frame | Relative power level at supergroup distribution frame | | Impedance at supergroup distribution frame | +|-----------------------------------------------------------|----------|--------------------------------------------------|---------------|------------------------------------------|-------------------------------------------------------|---------------|--------------------------------------------| +| | | Transmit (dBr) | Receive (dBr) | | Transmit (dBr) | Receive (dBr) | | +| Federal Republic of Germany | | -36 | -30 | 150 ohms, balanced | -35 | -30 | 75 ohms, unbalanced | +| Australia
Denmark a) | System 1 | -36.5 | -30.5 | 150 ohms, symetrique | -35 | -30.5 | id. | +| | System 2 | -42 | -5 | 135 ohms, balanced | -35 | -30 | id. | +| Austria | | -37
-36 | -8
-30 | 75 ohms, unbalanced
150 ohms balanced | -35 | -30 | id. | +| Belgium | | -37 | -8 | 150 ohms, balanced | -35 | -30 | id. | +| People's Republic of Bulgaria | | -36 | -23 | 150 ohms, balanced | -36 | -23 | id. | +| Spain, Ireland, New Zealand, Norway, United Kingdom | | -37 | -8 | 150 ohms, unbalanced | -35 | -30 | id. | +| USA
(American Telephone and Telegraph Company) | | -42 | -5 | 135 ohms, balanced | -25 | -28 | id. | +| France | | -33 | -15 | 150 ohms, balanced | -45 | -35 | id. | +| Hungary, Italy, Netherlands | | -37 | -30 | 150 ohms, balanced | -35 | -30 | id. | +| India | | -36.5 | -30.4 | 150 ohms, balanced | -34.8 | -30.4 | id. | +| Japan (Nippon Telegraph and Telephone Public Corporation) | | -36 | -18 | 75 ohms, balanced | -29 | -29 | id. | +| Mexico
(Teléfonos de México) | | -47 | -10 | 150 ohms, balanced | -47 | -24 | id. | + +TABLE 1/G.233 (continued) + +| | | | | | | | +|-----------------------------|-------|-------|---------------------|-----|-----|-----| +| People's Republic of Poland | -36 | -23 | 150 ohms, balanced | -36 | -23 | id. | +| German Democratic Republic | -36 | -23 | 150 ohms, balanced | -36 | -23 | id. | +| Sweden | | | | -35 | -30 | id. | +| Switzerland | -36.5 | -30.5 | 75 ohms, unbalanced | -35 | -26 | id. | +| USSR | -36 | -23 | 150 ohms, balanced | -36 | -23 | id. | + +a) System 1 only. + +### 4 Relative power levels at mastergroup distribution frames + +The relative power levels at mastergroup distribution frames (see Figure 6/G.233) should be adjusted to the following values: + +- transmit: -36 dBr, +- receive: -23 dBr, + +across a 75-ohm impedance, unbalanced to earth. + +![Diagram of relative levels at mastergroup distribution frame showing transmit and receive paths with power levels and equipment labels.](07b17a620c75522d53916a11e12d1bff_img.jpg) + +The diagram illustrates the signal flow and power levels at a mastergroup distribution frame. It is divided into two main horizontal sections: the transmit path (top) and the receive path (bottom). + +- Transmit Path:** On the left, a box labeled "Supergroup distribution frame" contains a symbol for a transmitter (triangle and sine wave). An arrow points from this symbol to a point on a dashed line labeled "Relative level -36 dBr". This dashed line connects to another transmitter symbol on the right, which then points to an output labeled "Line". +- Receive Path:** On the right, a box labeled "Mastergroup translating equipment" contains a symbol for a receiver (sine wave and triangle). An arrow points from this symbol to a point on a dashed line labeled "Relative level -23 dBr". This dashed line connects back to the "Supergroup distribution frame" on the left. +- Filter:** In the center, between the two dashed lines, is a box labeled "Through-master-group filter" containing a symbol for a filter (three squiggly lines). A label "Maximum attenuation 13 dB" is next to it. +- Labels:** The top horizontal line is labeled "Mastergroup distribution frame". The left vertical section is bracketed and labeled "Supergroup distribution frame". The bottom left box is labeled "Supergroup translating equipment (supergroups 4 to 8)". The bottom right box is labeled "Mastergroup translating equipment" and "CCITT - 45291". + +Diagram of relative levels at mastergroup distribution frame showing transmit and receive paths with power levels and equipment labels. + +FIGURE 6/G.233 + +#### Relative levels at mastergroup distribution frame + +### 5 Relative levels at supermastergroup distribution frames + +Relative power levels at supermastergroup distribution frames should be adjusted to the following values: + +- transmit: -33 dBr, +- receive: -25 dBr, + +across a 75-ohm impedance, unbalanced to earth. + +### 6 Relative levels at the distribution frame of 15-supergroup assembly (No. 1) + +The relative power levels at the 15-supergroup assembly distribution frame should be adjusted to the following values: + +- send: -33 dBr, +- receive: -25 or -33 dBr, + +across a 75-ohm impedance, unbalanced to earth. + +### 7 Return loss + +In relation to the nominal impedance, the return loss at the input and output of the translating equipment of supergroups, mastergroups, supermastergroups and 15-supergroup assemblies should not be lower than 20 dB in the wanted frequency band for both directions (send and receive) of transmission. + +With respect to the group translating equipment, the same limit applies at the high-frequency side; at the low-frequency side, it is also valid except in those areas in the vicinity of the group and supergroup pilots such as: + +- the band 103.7-104.6 kHz of group 3 when there is a stop filter for the 411.920 kHz pilot; +- the band 63.7-64.6 kHz of group 5 when there is a stop filter for the 547.920 kHz pilot. + +The above limits relate to the intrinsic return loss, i.e., that obtained when the cords connecting the measuring apparatus to the equipment are as short as possible. In view of the station cabling encountered in practice, the return loss recorded at the distribution frame of groups, supergroups, etc., may differ from the intrinsic return loss. This factor should be taken into account in designing and establishing the links. + +### 8 Noise + +Recommendation G.222, § 4 gives information on the noise produced by group, supergroup, mastergroup and 15-supergroup assembly translating equipment. + +### 9 Interference related to supergroup reference pilot + +Interference from, or with, supergroup reference pilots may be avoided by taking suitable precautions in channel terminal equipments or group-translating equipment (see Recommendation G.232, § 13.2 and the Recommendation cited in [2]). + +#### 9.1 Pilots at 411.860 and 411.920 kHz + +9.1.1 For the protection of pilots at a through-connection point (see Recommendation G.243), group 3 should at the receive end of a supergroup link be through-connected without demodulation, for example to another supergroup link; the modulating equipment for group 3 should present an attenuation of at least 20 dB at the frequency of the supergroup pilot. + +9.1.2 Moreover, when an Administration wishes to route 8- or 12-channel groups free between one supergroup link and another with no restrictions on routing of group 3, then the group 3 modulating and group 3 demodulating equipment should each provide in all cases at least 20 dB suppression at the frequency of the supergroup reference pilot. + +#### 9.2 *Pilot at 547.920 kHz* + +If this pilot is used in a supergroup transmitting five groups (regardless of the use made of these groups) and not a wideband signal (for data, etc.) occupying most of the frequency band, the arrangements mentioned in § 9.1 above for the group 3 equipment should be adopted in the modulating and demodulating equipment of group 5. + +### **10 Accuracy of carrier frequencies** + +See Recommendation G.225, § 1). + +### **11 Carrier leaks** + +11.1 The carrier leak at the transmit side of a modulation stage should not exceed: + +-47 dBm0 for group modulation, + +-50 dBm0 for supergroup modulation, + +-45 dBm0 for mastergroup modulation, + +-50 dBm0 for supermastergroup modulation and 15-supergroup assembly modulation, + +-30 dBm0 for 15-supergroup assemblies Nos. 2 and 3 on 12-MHz and 60-MHz systems, and for the first modulation stage of 15-supergroup modulation on 60-MHz systems, since in this case the carrier leaks fall into bands of frequencies not used for traffic. + +11.2 Higher levels of carrier leaks can be tolerated at the output of a modulation stage at the receive side, provided no interference with adjacent groups, etc. occurs (e.g. by way of backward carrier leak, etc.) + +11.3 In the case of sound-programme transmission according to the Recommendation cited in [3] certain channel carrier leaks, pregroup carrier leaks etc. falling in adjacent groups may cause excessive interference. In order to meet Recommendation cited in [4] the level of such leaks, measured at the supergroup distribution frame or an equivalent point, should not be higher than the values indicated below: + +-75 dBm0 in the frequency ranges 73-82 kHz and 86-95 kHz, + +-55 dBm0 at 67 kHz and 101 kHz. + +In the frequency bands 67-73 kHz and 95-101 kHz the requirements are based on straight lines (linear frequency and dB scales) connecting the limits indicated above. + +*Note 1* - It is recognized that there are several possibilities of meeting this recommended limit, such as allocating the necessary attenuation wholly or partly to the channel or group translating equipment respectively, to insert special filters at the group distribution frame, or by selection of groups. + +*Note 2* - The above limit is applicable to the transmit side only. + +*Note 3* - The 7 dB margin between the Recommendation cited in [4] and § 11.3 above allows for cumulation on the group links involved. + +11.4 In the case of 3-kHz spaced channels, the following recommendations apply: + +When a baseband carries 3-kHz or a mixture of 3- and 4-kHz channels, the level of each carrier leak should not exceed the value given in Table 2/G.233 (limits apply to transmit path only). + +TABLE 2/G.233 + +| Carrier leak of: | Group and supergroup carrying 3 kHz channels | Recommended limit, dBm0 | +|---------------------------------------|----------------------------------------------------------------------------------------|-------------------------| +| Groups 1, 2, and 3 of any supergroup | Same supergroup | —60 a) | +| Groups 4 and 5 of supergroups 4 to 16 | Groups 1 and 2 respectively of the adjacent lower supergroup (i.e. supergroup 3 to 15) | —73 a),b) | +| Supergroup 1 | Supergroup 3 | —60 a),b) | +| Supergroups 3 to 14 | Group 4 of supergroups 5 to 16 respectively | —73 a) | + +a) Based on Recommendation G.235 relating to subgroup carrier leaks. + +b) Based on the assumption that the interference limit per single frequency is -73 dBm0p. + +The filters of the supergroup translating equipment may contribute to the suppression of the group 4 and 5 carrier leaks. + +Special attention is also necessary to avoid backward carrier leaks in the demodulation stage that may result in a product falling into a 3-kHz channel in either the group or supergroup demodulation stage. + +*Note* - No allowance has been given for cumulation. The effects of cumulation are offset at least in part by the noise masking effect of long interconnected sections that commonly accompany the use of 3-kHz channel equipments. + +### 12 Go-to-return crosstalk + +The following limits are recommended for crosstalk ratios (single frequency measurements) for group and higher order translating equipments; they will apply to both the low and high frequency sides: + +- group translation: 80 dB; +- higher order translation stages: 85 dB. + +*Note* - On the basis of telephony considerations alone, a limit of 80 dB would have been proposed for all translation stages; this would also have sufficed to meet the recommended limit for intelligible crosstalk between programme circuits (74 dB in Recommendation J.21 [5]) in networks where programme circuits are systematically equipped with compandors. However, importance was attached to adopting a single requirement for each translation stage which would suffice for the most demanding network conditions to be encountered. + +### 13 Group-delay distortion + +#### 13.1 Group translating equipment + +It is recommended that the limits in Figure 7/G.233 for the group-delay distortion (relative to the value at 84 kHz) should not be exceeded by a group translating equipment consisting of a pair of group transmitting and receiving equipments. The given values are applicable to groups 2, 3 and 4 (without additional pilot stop filters). Groups 1 and 5 are excluded due to additional distortions caused by various sources (pilot stop filters, position at the end of the supergroup band, etc.); group 3 may be excluded, when the supergroup pilot 411.92 kHz or 411.86 kHz is used. + +*Note* - The range of measured values on modern equipments is indicated in Supplement 17 at the end of this fascicle. + +![Figure 7/G.233: A graph showing the group-delay distortion (ΔT) in microseconds (μs) versus frequency in kHz. The y-axis ranges from -5 to 25 μs, with major ticks at -5, 0, 10, 15, and 25. The x-axis ranges from 60 to 108 kHz, with major ticks at 60, 64, 68, 72, 84, 96, 100, 104, and 108. The graph shows a shaded region representing the allowed distortion limits. The upper limit is 25 μs from 64 to 68 kHz, then drops to 15 μs from 68 to 72 kHz, then to 10 μs from 72 to 96 kHz, then to 15 μs from 96 to 100 kHz, and finally to 25 μs from 100 to 104 kHz. The lower limit is -5 μs from 64 to 104 kHz. A small circle is marked on the x-axis at 84 kHz. The text 'CCITT - 32840' is in the bottom right corner.](252ea48d02dce93965b91746fb376f35_img.jpg) + +| Frequency (kHz) | Group-delay distortion (ΔT) (μs) | +|-----------------|----------------------------------| +| 60 - 64 | 0 | +| 64 - 68 | 25 | +| 68 - 72 | 15 | +| 72 - 96 | 10 | +| 96 - 100 | 15 | +| 100 - 104 | 25 | +| 104 - 108 | 0 | + +Figure 7/G.233: A graph showing the group-delay distortion (ΔT) in microseconds (μs) versus frequency in kHz. The y-axis ranges from -5 to 25 μs, with major ticks at -5, 0, 10, 15, and 25. The x-axis ranges from 60 to 108 kHz, with major ticks at 60, 64, 68, 72, 84, 96, 100, 104, and 108. The graph shows a shaded region representing the allowed distortion limits. The upper limit is 25 μs from 64 to 68 kHz, then drops to 15 μs from 68 to 72 kHz, then to 10 μs from 72 to 96 kHz, then to 15 μs from 96 to 100 kHz, and finally to 25 μs from 100 to 104 kHz. The lower limit is -5 μs from 64 to 104 kHz. A small circle is marked on the x-axis at 84 kHz. The text 'CCITT - 32840' is in the bottom right corner. + +FIGURE 7/G.233 + +#### 13.2 Supergroup translating equipment + +It is recommended that the limits in Figure 8/G.233 for the group-delay distortion (relative to the value at 412 kHz) should not be exceeded by a supergroup translating equipment consisting of a pair of supergroup transmitting and receiving equipments. The given values are not applicable to supergroups 1 and 3. Depending on the design of supergroup translating equipment this restriction may also apply to supergroups 6 and 7 (due to pilot protection filter). + +*Note* - The range of measured values on modern equipments is indicated in Supplement 17 at the end of this fascicle. + +![Graph of Group-delay distortion (Δτ) in μs versus Frequency in kHz. The y-axis ranges from -2 to 4.5 μs, with a zero line. The x-axis ranges from 312 to 552 kHz, with markers at 312, 352, 364, 412, 500, 512, and 552. The graph shows a shaded region representing the allowed distortion limits. The upper limit is 4.5 μs from 312 to 352 kHz, then drops to 3.5 μs from 364 to 500 kHz, and rises back to 4.5 μs from 512 to 552 kHz. The lower limit is -2 μs from 352 to 512 kHz. A small circle is marked on the zero line at 412 kHz. The text 'CCITT - 32851' is in the bottom right corner.](dd0f5301a5a6dd7c319701302110de88_img.jpg) + +Graph of Group-delay distortion (Δτ) in μs versus Frequency in kHz. The y-axis ranges from -2 to 4.5 μs, with a zero line. The x-axis ranges from 312 to 552 kHz, with markers at 312, 352, 364, 412, 500, 512, and 552. The graph shows a shaded region representing the allowed distortion limits. The upper limit is 4.5 μs from 312 to 352 kHz, then drops to 3.5 μs from 364 to 500 kHz, and rises back to 4.5 μs from 512 to 552 kHz. The lower limit is -2 μs from 352 to 512 kHz. A small circle is marked on the zero line at 412 kHz. The text 'CCITT - 32851' is in the bottom right corner. + +FIGURE 8/G.233 + +## References + +- [1] CCITT Recommendation *8-channel terminal equipments*, Orange Book, Vol. III-I, Rec. G.234, ITU, Geneva, 1977. +- [2] *Ibid.*, § f) 2. +- [3] CCITT Recommendation *Characteristics of equipment lines used for setting up 15-kHz type sound-programme circuits*, Vol. III, Rec. J.31, § 1. +- [4] *Ibid.*, § 2. +- [5] CCITT Recommendation *Performance characteristics of 15-kHz type sound-programme circuits*, Vol. III, Rec. 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A lightning bolt symbol is positioned to the right of the globe. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.422** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**INTERNATIONAL ANALOGUE CARRIER SYSTEMS +GENERAL CHARACTERISTICS OF INTERNATIONAL +CARRIER TELEPHONE SYSTEMS ON +RADIO - RELAY OR SATELLITE LINKS AND +INTERCONNECTION WITH METALLIC LINES** + +--- + +**INTERCONNECTION AT AUDIO-FREQUENCIES** + +**ITU-T Recommendation G.422** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +- 1 ITU-T Recommendation G.422 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## Recommendation G.422 + +# INTERCONNECTION AT AUDIO-FREQUENCIES + +CCIR Recommendation 268 [1] states that, as far as is practicable, radio-relay systems for telephony providing circuits which may form part of an international connection should be such that these circuits conform with the relevant CCIR Recommendations for modern types of telephone circuit in the following respects: + +- 1) the transmission characteristics of the circuits between audio-frequency terminals (the relevant Recommendations are contained in Section 1 of this Part); +- 2) the characteristics of the multiplex terminal equipment, where applicable (see Recommendations G.232 and G.412); +- 3) the method of signalling over international circuits, the relevant Recommendations are contained in Volume VI; see also the following Note: + +*Note* - Since the CCITT Recommendations mentioned in 2) above envisage the use of well-defined audio signalling frequencies sent over the speech path, no signal repetition problems should arise. + +When different signalling methods are used on a cable system and a radio-relay system, equipment will be necessary at the interconnection point to convert the two types of signalling to a common type, preferably d.c. signalling. + +## Reference + +- [1] CCIR Recommendation *Interconnection at audio frequencies of radio-relay systems for telephony*, Vol. IX, Rec. 268, Dubrovnik, 1982. \ No newline at end of file diff --git a/marked/G/T-REC-G.613-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.613-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..2d4fe13ea9c515d69eb064c8c2f48bf2f8c91709 --- /dev/null +++ b/marked/G/T-REC-G.613-198811-I_PDF-E/raw.md @@ -0,0 +1,189 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.613** + +# **TRANSMISSION MEDIA CHARACTERISTICS** + +--- + +**CHARACTERISTICS OF SYMMETRIC CABLE +PAIRS USABLE WHOLLY FOR THE +TRANSMISSION OF DIGITAL SYSTEMS WITH +A BIT RATE OF UP TO 2 Mbits** + +**ITU-T Recommendation G.613** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +- 1 ITU-T Recommendation G.613 was published in Fascicle III.3 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## **CHARACTERISTICS OF SYMMETRIC CABLE PAIRS USABLE WHOLLY FOR THE TRANSMISSION OF DIGITAL SYSTEMS WITH A BIT RATE OF UP TO 2 Mbits** + +*(Malaga-Torremolinos, 1984)* + +## **1 Preamble** + +This Recommendation deals with cables designed for the transmission of standard digital systems (Recommendations of the G.900 series), although these cables can also be used to transmit digital signals with a lower bit rate and voice frequency signals. The cables described carry signals in both transmission directions simultaneously. The provisions of this Recommendation apply to cables designed to allow for digital operation of all the cable circuits. However, some of the provisions may be used to assess the possibility of (partial or full) digital operation of existing cables. + +## **2 Parameters to be measured** + +### **2.1 Direct current resistance** + +The following formula is used to correct the value $R_t$ of direct current resistance measured at $t^\circ\text{C}$ for $20^\circ\text{C}$ : + +$$R_{20} = R_t / (1 + 0.004 (t - 20))$$ + +### **2.2 Capacitance per unit length** + +This is measured at 800 Hz or 1000Hz. + +### **2.3 Attenuation coefficient** + +The value of the attenuation coefficient is obtained either by direct measurement of the attenuation or by calculation on the basis of the mutual capacitance and direct current resistance of the pair. The attenuation coefficient is measured at one frequency only, $f_0$ , near the timing half-frequency. + +| System | Recommendation | $f_0$ | +|-------------|----------------|---------| +| 1544 kbit/s | G.951 | 772 kHz | +| 2048 kbit/s | G.952 | 1 MHz | + +For cables with polyolefin insulation, the value of the attenuation coefficient at frequency $f$ (for values of $f$ above with a few hundred kHz) can be related to $\alpha_0$ by the equation $\alpha_f = \alpha_0 \sqrt{\frac{f}{f_0}}$ . + +The value of the attenuation coefficient measured at $t^\circ\text{C}$ is corrected for $20^\circ\text{C}$ by the equation: + +$$\alpha_{20} = \alpha_t / (1 + 0.002 (t - 20))$$ + +### 2.4 Characteristic impedance + +#### 2.4.1 Echometric measurement + +When a pulse echometer is used, the impedance of the pair measured must be compensated by a calibrated balancing network which can be set in steps of about 0.5 Ω. Pulse duration will be equal to or less than 500 ns. With this method, which is both fast and simple, the value of the end impedance of the pair measured is read off directly on the scale of the balancing network. + +#### 2.4.2 Sinusoidal measurement + +In this case, the pair tested will be terminated across an impedance, which is constantly equal to that measured by the bridge, unless it is long enough for the result of the measurement to be independent of end impedance (as for elementary cable sections). + +### 2.5 Crosstalk + +Crosstalk can be measured sinusoidally or digitally. The assignment of pairs to the direction of transmission depends on the structure and type of manufacture of the cable. + +#### 2.5.1 Sinusoidal measurement + +##### 2.5.1.1 Far-end crosstalk + +The measurements are made between pairs assigned to the same direction of transmission, at frequency $f_0$ . If the frequency at which measurement is carried out is not the timing half-frequency, the value is corrected using the $20 \log_{10} f$ law. When the measurement is carried out on a pair of length, $L$ , which is different from the specified reference length $L_0$ , the measured value is corrected using $\sqrt{L/L_0}$ when the value is expressed in mV or $10 \log_{10} \frac{L}{L_0}$ when the value is expressed in dB. + +##### 2.5.1.2 Near-end crosstalk + +The measurements are made between pairs assigned to transmission in opposite directions at a frequency near the system's timing half-frequency. + +#### 2.5.2 Digital measurement + +By means of digital measurement, it is possible to estimate the total noise on an elementary section, taking account of both near-end and far-end crosstalk. This estimate can be made on the basis of separate near-end and far-end crosstalk measurements on either factory lengths or elementary sections.1) These measurements can be made either in factory conditions or on installed cables. + +##### 2.5.2.1 Far-end crosstalk + +The measurements are carried out between pairs assigned to the same direction of transmission. When the measurement is carried out on a pair of length, $L$ , which is different from the specified reference length $L_0$ , the measured value is corrected using $\sqrt{L/L_0}$ when the value is expressed in mV or $10 \log_{10} (L/L_0)$ when the value is expressed in dB. + +##### 2.5.2.2 Near-end crosstalk + +The measurements are made between pairs *assigned* to transmission in opposite directions. + +## 3 Circuit characteristics + +These are given in Table 1/G.613. + +--- + +1) One advantage of digital measurements is that it is possible to make a direct overall measurement of the total noise on an elementary section if enough generators are available. + +## 4 Characteristics of connected cable sections + +These are given in Table 2/G.613. + +TABLE 1/G.613 +Circuit characteristics \* + +| Characteristics | | Type of cable | | | | | | +|-------------------------------------------------------------------|---------------|---------------|----------|-----------------------|------------------|----------|--| +| | | Type I | Type II | Type II
bis | Type III
**** | f) | | +| Operational bit rate (kbit/s) | | 2048 | 2048 | 2048 | 2048 | | | +| Repeaters gain ** | | 34 dB | | | | | | +| Elements constituting the cable | | star quad | pairs | pairs | pairs | | | +| Nominal conductor diameter (mm) | | 0.8 | 0.7 | 1 | 0.6 | | | +| Nominal impedance *** at $f_0$ MHz (Ω) | 1 MHz | 100 | 130 | 130 | | | | +| | 772 kHz | | | | | | | +| Nominal attenuation coefficient at $f_0$ and at 20° C *** (dB/km) | 1 MHz | 16 | 11.5 b) | 8.5 b) | 15.5 | | | +| | 772 kHz | | | | | | | +| Crosstalk in digital operation | | a) | c) | - | - | - | | +| Total noise voltage (maximum value) | | a) | | | | | | +| Minimum near-end crosstalk (mV) | a) | - | 60 d, g) | 60 d, g) | | | | +| | a) | | | | | | | +| Minimum far-end crosstalk (mV) | a) | - | 45 e, g) | 45 e, g) | | | | +| | a) | | | | | | | +| Sinusoidal crosstalk | Near-end (dB) | 1 MHz | | | | 78 ± 3h) | | +| | | 772 kHz | | | | | | +| | Far-end (dB) | 1 MHz | | | | 64 ± 3h) | | +| | | 772 kHz | | | | | | +| Nominal direct current resistance at 20°C (Ω/km) | | | 68.6 | 94.1 b) | 46.1 b) | 63 | | +| Nominal mutual capacitance (nF/km) | | | 50 | 39 | 39 | 44 | | + +### Notes of Table 1/G.613 + +- \* At the present stage the values are given for information. + - \*\* Reference value for the numerical data of the cable in question. + - \*\*\* A standard deviation or margins will be given at a later stage. + - \*\*\*\* Cable with diametral screen separating the pairs assigned to the two directions of transmission. +- a) To be specified. + - b) Maximum value. + - c) The specification value for factory controls is calculated to ensure compliance with the characteristics of connected cable. + - d) Between pairs of different groups. + - e) Between pairs belonging to one and the same group. + - f) Other columns will contain the data supplied by administrations. + - g) Values given in dB. + - h) The value given here depends on the content of the cable. It is the rounded-down mean of a standard deviation of the total production and is therefore not a specification for individual cable lengths. + +TABLE 2/G.613 + +### **Characteristics of connected cable sections \*** + +| Characteristics | | Type of cable | | | | | +|--------------------------------------------------------------|---------------------|---------------|---------|-------------|----------|----| +| | | Type I | Type II | Type II bis | Type III | a) | +| Operational bit rate (kbit/s) | | 2048 | 2048 | 2048 | | | +| Nominal impedance at $f_0$ MHz ( $\Omega$ ) | 1 MHz | 100 | 130 | 130 | | | +| | 772 kHz | | | | | | +| Nominal attenuation coefficient at $f_0$ and at 20°C (dB/km) | 1 MHz | 16 | 11.5 | 8.5 | | | +| | 772 KHz | | | | | | +| Crosstalk in digital operation | b) | 40 mV | | | | | +| Total noise voltage (maximum value) | b) | | | | | | +| Minimum near-end crosstalk (mV) | b) | | | | | | +| | b) | | | | | | +| Minimum far-end crosstalk (mV) | b) | | | | | | +| | b) | 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Recommendation**ITU-T G.650.1 (01/2024)** + +SERIES G: Transmission systems and media, digital systems and networks + +Transmission media and optical systems characteristics – +Optical fibre cables + +--- + +### **Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable** + +![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **Transmission systems and media, digital systems and networks** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100-G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200-G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300-G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400-G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450-G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600-G.699 | +| General | G.600-G.609 | +| Symmetric cable pairs | G.610-G.619 | +| Land coaxial cable pairs | G.620-G.629 | +| Submarine cables | G.630-G.639 | +| Free space optical systems | G.640-G.649 | +| Optical fibre cables | G.650-G.659 | +| Characteristics of optical components and subsystems | G.660-G.679 | +| Characteristics of optical systems | G.680-G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700-G.799 | +| DIGITAL NETWORKS | G.800-G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900-G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000-G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000-G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000-G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000-G.8999 | +| ACCESS NETWORKS | G.9000-G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.650.1 + +# Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable + +## Summary + +Recommendation ITU-T G.650.1 contains definitions of the linear, deterministic parameters of single-mode optical fibres and cables. It also contains both reference test methods and alternative test methods for characterizing these parameters. + +These test methods are suitable mainly for factory measurements of the linear, deterministic attributes of single-mode fibres and cables. Some of the test methods may also be used to characterize discrete optical components. + +The history of this Recommendation is as follows: + +- 1993 Definitions and test methods were removed from single-mode fibre Recommendations such as Recommendation ITU-T G.652 and used to create the initial version of Recommendation ITU-T G.650. +- 1997 The second version of Recommendation ITU-T G.650 added definitions and test methods for polarization mode dispersion and appendices I, II and III. The improved determination of cut-off wavelength (clause 5.3.1.3.4) was also added. +- 2000 The third version established reference and alternative test methods for polarization mode dispersion, modified the definitions and test methods for core concentricity error (clauses 3.4 and 5.2), and added clause 5.1.4 and appendices IV, V and VI. +- 2002 In order to facilitate maintenance, Recommendation ITU-T G.650 was divided into smaller Recommendations. Recommendation ITU-T G.650.2 contains definitions and test methods for statistical and non-linear attributes of single-mode fibre and cable. +- 2004 The second version of Recommendation ITU-T G.650.1 added a third alternative test method "Spectral attenuation modelling" (clause 5.4.4) and new Appendix III "Example of a matrix model". This material has been moved from the single-mode fibre Recommendations into this Recommendation ITU-T G.650.1. In addition, chromatic dispersion fitting procedures have been added (Annex A). +- 2010 The third version of Recommendation ITU-T G.650.1 added the test method "Test methods for the macrobend loss" (clause 5.6). Jumper cut-off wavelength has been deleted from clause 5.3. An additional description has been added in cut-off wavelength test method (clause 5.3.1.3.2). Equation 5-1 has been corrected. A detailed description has been added in proof test method (clause 5.7). Appendix II has been updated. +- 2018 The fourth version of Recommendation ITU-T G.650.1 added Appendix IV (from Amendment 1 published in 2012) to provide measurement procedures for coherent multipath interference (MPI). The interferometric technique for chromatic dispersion measurement has been deleted from clause 6.5 and moved to Appendix V. The description of measurement details for ITU-T G.657 fibre on MFD, cut-off wavelength and spectral attenuation tests has been improved. The RTM and ATM of cable cut-off wavelength measurement has been modified. An example of the interpolation method has been added in clause I.3. Equation 6-1 has been corrected. +- 2020 The fifth version of Recommendation ITU-T G.650.1 revised third alternative test method "Spectral attenuation modelling" (clause 6.4.4) to cover the applicability of fewer predictor wavelengths for the modelling of much narrower wavelength range. In Appendix III, + +"Example of a matrix model", existing example matrix for ITU-T G.652 fibre was replaced with a new matrix using four predictor wavelengths, and added a new matrix for ITU-T G.654.E fibre using three predictor wavelengths. Wavelength dependence of modelling error as a function of the number of predictor wavelengths was explained. + +- 2023 The sixth version of Recommendation ITU-T G.650.1 revised reference test method "The far-field scan" (clause 6.1.1). The resolution factor $K$ has been introduced as the relation between the active area of the detector and the distance from fibre end. The minimum dynamic range has been generalized. The description of the detector for the far-field scan has been modified. In addition, a maximum numerical aperture of 0.4 is recommended for ITU-T G.655 and G.656 fibres in addition to ITU-T G.653 fibre in first alternative test method "The variable aperture technique" (clause 6.1.2). + +## History \* + +| Edition | Recommendation | Approval | Study Group | Unique ID | +|---------|-----------------------------|------------|-------------|--------------------| +| 4.0 | ITU-T G.650.1 | 2002-06-29 | 15 | 11.1002/1000/6072 | +| 4.1 | ITU-T G.650.1 (2002) Amd. 1 | 2003-03-16 | 15 | 11.1002/1000/6259 | +| 5.0 | ITU-T G.650.1 | 2004-06-13 | 15 | 11.1002/1000/7319 | +| 6.0 | ITU-T G.650.1 | 2010-07-29 | 15 | 11.1002/1000/10868 | +| 6.1 | ITU-T G.650.1 (2010) Amd. 1 | 2012-10-29 | 15 | 11.1002/1000/11767 | +| 6.2 | ITU-T G.650.1 (2010) Cor. 1 | 2013-08-29 | 15 | 11.1002/1000/11981 | +| 7.0 | ITU-T G.650.1 | 2018-03-16 | 15 | 11.1002/1000/13516 | +| 8.0 | ITU-T G.650.1 | 2020-10-29 | 15 | 11.1002/1000/14536 | +| 9.0 | ITU-T G.650.1 | 2024-01-13 | 15 | 11.1002/1000/15803 | + +## Keywords + +Deterministic attributes, linear attributes, single-mode fibre characterization. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2024 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|-------|------------------------------------------------------------------------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | General definitions ..... | 2 | +| 3.2 | Mechanical characteristics..... | 2 | +| 3.3 | Glass geometry characteristics ..... | 2 | +| 3.4 | Optical characteristics ..... | 3 | +| 3.5 | Others ..... | 6 | +| 4 | Abbreviations and acronyms ..... | 6 | +| 5 | Conventions ..... | 6 | +| 6 | Test methods..... | 6 | +| 6.1 | Test methods for the mode field diameter ..... | 7 | +| 6.2 | Test methods for the cladding diameter, core concentricity error and cladding non-circularity..... | 14 | +| 6.3 | Test methods for the cut-off wavelength..... | 23 | +| 6.4 | Test methods for attenuation ..... | 30 | +| 6.5 | Test methods for chromatic dispersion..... | 42 | +| 6.6 | Test methods for macrobend loss ..... | 46 | +| 6.7 | Test methods for proof testing..... | 48 | +| | Annex A – Chromatic dispersion fitting ..... | 53 | +| A.1 | General ..... | 53 | +| A.2 | Definition of equations and fitting coefficients..... | 53 | +| A.3 | Fitting procedure ..... | 54 | +| | Appendix I – Methods of cut-off wavelength interpolation ..... | 55 | +| I.1 | Limited negative error method ..... | 55 | +| I.2 | Least squares method ..... | 57 | +| I.3 | Example..... | 57 | +| | Appendix II – Test method for measuring longitudinal uniformity of chromatic dispersion based on the backscattering technique..... | 58 | +| II.1 | General ..... | 58 | +| II.2 | Test apparatus..... | 58 | +| II.3 | Measurement procedure ..... | 59 | +| II.4 | Presentation of the results..... | 62 | +| | Appendix III – Example of a matrix model ..... | 63 | +| III.1 | Example characterizing matrices for ITU-T G.652.D and ITU-T G.654.E fibre..... | 63 | +| III.2 | Illustrative relationship with predictor wavelengths ..... | 66 | + +| | | +|----------------------------------------------------------------------------------------------------|----| +| Appendix IV – Test methods for measuring coherent MPI in short optical fibre cables (jumpers)..... | 68 | +| IV.1    First test method: The narrowband ECL/PM technique..... | 68 | +| IV.2    Second test method: The wideband LED/OSA technique ..... | 71 | +| IV.3    Third test method: The fibre stretching technique ..... | 73 | +| Appendix V – The interferometric technique for chromatic dispersion measurement..... | 77 | +| V.1    General ..... | 77 | +| V.2    Test apparatus..... | 77 | +| V.3    Measurement procedure ..... | 79 | +| V.4    Presentation of the results..... | 79 | +| Bibliography..... | 81 | + + + +# Recommendation ITU-T G.650.1 + +# Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable + +## 1 Scope + +This Recommendation contains definitions and test methods suitable mainly for factory measurements of the linear, deterministic attributes of the single-mode optical fibres and cables described in [ITU-T G.652], [ITU-T G.653], [ITU-T G.654], [ITU-T G.655], [ITU-T G.656] and [ITU-T G.657]. These definitions and test methods are generally not appropriate for multimode fibre, such as that specified in [ITU-T G.651.1]. Some of the test methods, when so indicated, may also be used to characterize discrete optical components, such as those described in [ITU-T G.671]. [ITU-T G.650.2] contains definitions and test methods for statistical and non-linear attributes. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.650.2] Recommendation ITU-T G.650.2 (2015), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable*. +- [ITU-T G.651.1] Recommendation ITU-T G.651.1 (2018), *Characteristics of a 50/125 µm multimode graded index optical fibre cable for the optical access network*. +- [ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*. +- [ITU-T G.653] Recommendation ITU-T G.653 (2010), *Characteristics of a dispersion-shifted single-mode optical fibre and cable*. +- [ITU-T G.654] Recommendation ITU-T G.654 (2020), *Characteristics of a cut-off shifted single-mode optical fibre and cable*. +- [ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable*. +- [ITU-T G.656] Recommendation ITU-T G.656 (2010), *Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport*. +- [ITU-T G.657] Recommendation ITU-T G.657 (2016), *Characteristics of a bending-loss insensitive single-mode optical fibre and cable*. +- [ITU-T G.671] Recommendation ITU-T G.671 (2019), *Transmission characteristics of optical components and subsystems*. +- [IEC 60793-1-1] IEC 60793-1-1 (2022), *Optical fibres – Part 1-1: Measurement methods and test procedures – General and guidance*. +- [IEC 60793-1-42] IEC 60793-1-42 (2013), *Optical fibres – Part 1-42: Measurement methods and test procedures – Chromatic dispersion. (Annex C, Differential phase shift test method.)* + +- [IEC 60793-1-44] IEC 60793-1-44 (2023), *Optical fibres – Part 1-44: Measurement methods and test procedures – Cut-off wavelength*. +- [IEC 60793-1-46] IEC 60793-1-46 (2001), *Optical fibres – Part 1-46: Measurement methods and test procedures – Monitoring of changes in optical transmittance*. +- [IEC 60793-1-47] IEC 60793-1-47 (2017), *Optical fibres – Part 1-47: Measurement methods and test procedures – Macrobending loss*. +- [IEC 61745] IEC 61745 (2017), *End-face image analysis procedure for the calibration of optical fibre geometry test sets*. +- [IEC 61746-1] IEC 61746-1 (2009), *Calibration of optical time-domain reflectometers (OTDR) – Part 1: OTDR for single mode fibres*. + +## 3 Definitions + +This Recommendation defines the following terms: + +### 3.1 General definitions + +**3.1.1 alternative test method (ATM):** A test method in which a given characteristic of a specified class of optical fibres or optical fibre cables is measured in a manner consistent with the definition of this characteristic and gives results which are reproducible and relatable to the reference test method and to practical use. + +**3.1.2 cladding mode stripper:** A device that encourages the conversion of cladding modes to radiation modes. + +**3.1.3 mode filter:** A device designed to accept or reject a certain mode or modes. + +**3.1.4 reference test method (RTM):** A test method in which a characteristic of a specified class of optical fibres or optical fibre cables is measured strictly according to the definition of this characteristic and which gives results which are accurate, reproducible and relatable to practical use. + +**3.1.5 refractive index profile:** The refractive index along a diameter of the fibre. + +### 3.2 Mechanical characteristics + +**3.2.1 proof test level:** The proof test level is the specified value of tensile stress or strain to which a full length of fibre is subjected for a short time period. This is usually done sequentially along the fibre length. + +**3.2.2 stress corrosion parameter:** The stress corrosion (susceptibility) parameter $n$ is a dimensionless coefficient empirically related to the dependence of crack growth on applied stress. It depends upon the ambient temperature, humidity and other environmental conditions. + +Both a static and a dynamic value for this parameter can be given. + +The static value $n_s$ is the negative of the slope of a static fatigue log-log plot of failure time versus applied stress. + +The dynamic value is $n_d$ where $1/(n_d + 1)$ is the slope of a dynamic fatigue log-log plot of failure stress versus applied stress rate. + +NOTE – $n$ need not be an integer. + +### 3.3 Glass geometry characteristics + +**3.3.1 cladding:** The outermost region of glass in the fibre cross section. + +**3.3.2 cladding centre:** The centre of a circle which best fits the cladding boundary. + +NOTE – The method of best fitting has to be specified. + +**3.3.3 cladding diameter:** The diameter of the circle defining the cladding centre. + +**3.3.4 cladding diameter deviation:** The difference between the actual and the nominal values of the cladding diameter. + +**3.3.5 cladding non-circularity:** The difference between the diameters of the two circles defined by the cladding tolerance field, divided by the cladding diameter. + +**3.3.6 cladding tolerance field:** For a cross section of an optical fibre, it is the region between the circle circumscribing the outer limit of the cladding, and the largest circle, concentric with the first one, that fits into the outer limit of the cladding. Both circles should have the same centre as the cladding. + +**3.3.7 core centre:** The core centre is the centre of a circle which best fits the points at a constant level in the near-field intensity pattern emitted from the central region of the fibre, using wavelengths above and/or below the fibre's cut-off wavelength. + +NOTE 1 – The above constant level should be chosen between 5% and 50% of maximum near-field intensity. + +NOTE 2 – Usually, the core centre represents a good approximation of the mode field centre. + +**3.3.8 core concentricity error:** The distance between the core centre and the cladding centre. + +### 3.4 Optical characteristics + +#### 3.4.1 mode field definitions + +**3.4.1.1 mode field:** The mode field is the single-mode field distribution of the LP01 mode giving rise to a spatial intensity distribution in the fibre. + +**3.4.1.2 mode field centre:** The mode field centre is the position of the centroid of the spatial intensity distribution in the fibre. + +NOTE 1 – The centroid is located at $r_c$ and is the normalized intensity-weighted integral of the position vector $r$ . + +$$r_c = \frac{\iint_{Area} r I(r) dA}{\iint_{Area} I(r) dA} \quad (3-1)$$ + +NOTE 2 – The correspondence between the position of the centroid, as defined, and the position of the maximum of the spatial intensity distribution requires further study. + +**3.4.1.3 mode field concentricity error:** The distance between the mode field centre and the cladding centre. + +**3.4.1.4 mode field diameter:** The mode field diameter (MFD) $2w$ represents a measure of the transverse extent of the electromagnetic field intensity of the mode in a fibre cross section, and it is defined from the far-field intensity distribution $F^2(\theta)$ , $\theta$ being the far-field angle, through the following equation: + +$$2w = \frac{\lambda}{\pi} \left[ \frac{2 \int_0^{\frac{\pi}{2}} F^2(\theta) \sin \theta \cos \theta d\theta}{\int_0^{\frac{\pi}{2}} F^2(\theta) \sin^3 \theta \cos \theta d\theta} \right]^{\frac{1}{2}} \quad (3-2)$$ + +**3.4.1.5 mode field non-circularity:** Since it is not normally necessary to measure mode field non-circularity for acceptance purposes, a definition of mode field non-circularity is not necessary in this context. + +#### **3.4.2 chromatic dispersion definitions** + +**3.4.2.1 chromatic dispersion:** The spreading of a light pulse in an optical fibre caused by the different group velocities of the different wavelengths composing the source spectrum. + +**3.4.2.2 chromatic dispersion coefficient:** Change of the group delay of a light pulse for a unit fibre length caused by a unit wavelength change. Thus, the chromatic dispersion coefficient is $D(\lambda) = d\tau/d\lambda$ . It is usually expressed in ps/(nm $\times$ km). + +**3.4.2.3 chromatic dispersion slope:** The slope of the chromatic dispersion coefficient versus wavelength curve. The dispersion slope is defined as $S(\lambda) = dD/d\lambda$ . + +**3.4.2.4 group delay:** The time required for a light pulse to travel a unit length of fibre. The group delay as a function of wavelength is denoted by $\tau(\lambda)$ . It is usually expressed in ps/km. + +**3.4.2.5 longitudinal uniformity of chromatic dispersion:** Change in the chromatic dispersion coefficient over the length of an optical fibre or cable. + +**3.4.2.6 zero-dispersion slope:** The chromatic dispersion slope at the zero-dispersion wavelength. + +**3.4.2.7 zero-dispersion wavelength:** The wavelength at which the chromatic dispersion vanishes. + +**3.4.3 cut-off wavelength:** Theoretical cut-off wavelength is the shortest wavelength at which a single mode can propagate in a single-mode fibre. This parameter can be computed from the refractive index profile of the fibre. At wavelengths below the theoretical cut-off wavelength several modes propagate and the fibre is no longer single-mode but multimode. + +In optical fibres, the change from multimode to single-mode behaviour does not occur at an isolated wavelength, but rather smoothly over a range of wavelengths. Consequently, for determining fibre performance in a telecommunication network, theoretical cut-off wavelength is less useful than the actual threshold wavelength for single-mode performance when the fibre is in operation. Thus, a more effective parameter called cut-off wavelength should be introduced for single-mode fibre specifications as defined in the following: + +Cut-off wavelength is defined as the wavelength greater than which the ratio between the total power, including launched higher order modes, and the fundamental mode power has decreased to less than 0.1 dB. According to this definition, the second order ( $LP_{11}$ ) mode undergoes 19.3 dB more attenuation than the fundamental ( $LP_{01}$ ) mode when the modes are equally excited. + +Because cut-off wavelength depends on the length and bends of the fibre, as well as its strain condition, the resulting value of cut-off wavelength depends on whether the measured fibre is configured in a deployed cabled condition, or whether the fibre is short and uncabled. Consequently, there are two types of cut-off wavelength defined: cable cut-off wavelength and fibre cut-off wavelength. + +**cable cut-off wavelength $\lambda_{cc}$** – Cable cut-off wavelength is measured prior to installation on a substantially straight 22 m cable length prepared by exposing 1 m of primary-coated fibre at either end, the exposed ends each incorporating a 40 mm radius loop. Alternatively, this parameter may be measured on 22 m of primary-coated uncabled fibre loosely constrained in loops $> 140$ mm radius, incorporating a 40 mm radius loop at either end. + +**fibre cut-off wavelength $\lambda_c$** – Fibre cut-off wavelength is measured on a short length of uncabled, primary-coated fibre. + +To avoid modal noise and dispersion penalties, the cut-off wavelength $\lambda_{cc}$ of the shortest cable length (including repair lengths when present) should be less than the lowest anticipated system wavelength, $\lambda_s$ : + +$$\lambda_{cc} < \lambda_s \quad (3-3)$$ + +This ensures that each individual cable section is sufficiently single mode. Any joint that is not perfect will create some higher order ( $LP_{11}$ ) mode power, and single-mode fibres typically support this mode for a short distance (of the order of metres, depending on the deployment conditions). A minimum distance should therefore be specified between joints in order to give the fibre sufficient distance to attenuate the $LP_{11}$ mode before it reaches the next joint. If inequality (3-3) is satisfied in the shortest cable section, it will be automatically satisfied in all longer cable sections, and single-mode system operation will occur regardless of the elementary section length. + +Fibre cut-off wavelength and mode field diameter can be combined to estimate a fibre's bend sensitivity. High fibre cut-off and a small mode field diameter result in a more bend-resistant fibre. This explains why it is often desirable to specify higher values of cut-off wavelength $\lambda_c$ , even if the upper limit of this parameter exceeds the operating wavelength. All practical installation techniques and cable designs will ensure a cable cut-off wavelength below the operating wavelength. + +Since specification of cable cut-off wavelength, $\lambda_{cc}$ , is a more direct way of ensuring single-mode cable operation, specifying this is preferred to specifying fibre cut-off wavelength, $\lambda_c$ . However, when circumstances do not readily permit the specification of $\lambda_{cc}$ (e.g., in single-fibre cable such as pigtails, jumpers or cables to be deployed in a significantly different manner than in the $\lambda_{cc}$ RTM), then specifying an upper limit for $\lambda_c$ is appropriate. This option is addressed in [ITU-T G.652], [ITU-T G.653], [ITU-T G.654], [ITU-T G.655], [ITU-T G.656] and [ITU-T G.657]. + +NOTE – The single-mode operability of a short (typically less than 10 m) optical fibre can be additionally investigated by evaluating the multipath interference (MPI). General information on MPI is provided in clause 6.1 of [b-ITU-T G.Sup.47] and coherent MPI test methods are described in Appendix IV of this Recommendation. + +**3.4.4 attenuation:** The attenuation $A(\lambda)$ at wavelength $\lambda$ between two cross sections 1 and 2 separated by distance $L$ of a fibre is defined as: + +$$A(\lambda) = 10 \log \frac{P_1(\lambda)}{P_2(\lambda)} \text{ (dB)} \quad (3-4)$$ + +where $P_1(\lambda)$ is the optical power traversing cross section 1, and $P_2(\lambda)$ is the optical power traversing cross section 2 at the wavelength $\lambda$ . + +For a uniform fibre, it is possible to define an attenuation per unit length or an attenuation coefficient, which is independent of the length of the fibre: + +$$a(\lambda) = \frac{A(\lambda)}{L} \text{ (dB/unit length)} \quad (3-5)$$ + +**3.4.5 macrobending loss:** The macrobending loss is the loss values under different bend radii, number of coils and wavelengths to evaluate the macrobending performance of optical fibres. The results are reported in dB as: + +$$Loss(dB) = 10 \log_{10} \left( \frac{P_{str}}{P_{bend}} \right) \quad (3-6)$$ + +where $P_{str}$ is the power measured without the bend and $P_{bend}$ is the power measured with the bend present. + +### 3.5 Others + +**3.5.1 primary coating:** The one or more layers of protective coating material applied to the fibre cladding during or after the drawing process to preserve the integrity of the cladding surface and to give a minimum amount of required protection (e.g., a 250 µm protective coating). + +**3.5.2 secondary coating:** The one or more layers of coating material applied over one or more primary-coated fibres in order to give additional required protection or to arrange fibres together in a particular structure (e.g., a 900 µm "buffer" coating, "tight jacket", or a ribbon coating). + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------|------------------------------------------| +| ATM | Alternative Test Method | +| CCD | Charge Coupled Device | +| ECL | External Cavity Laser | +| EELED | Edge Emitting Light Emitting Diode | +| FS | Fibre Stretching | +| FSR | Free Spectral Range | +| FWHM | Full Width at Half Maximum | +| HOM | High-Order Mode | +| LD | Laser Diode | +| LED | Light Emitting Diode | +| MFD | Mode Field Diameter | +| MPI | Multipath Interference | +| NA | Numerical Aperture | +| Nd YAG | Neodymium-doped Yttrium Aluminium Garnet | +| OSA | Optical Spectrum Analyser | +| OTDR | Optical Time Domain Reflectometer | +| PM | Power Meter | +| RIN | Relative Intensity Noise | +| RTM | Reference Test Method | +| TEM | Transverse Electromagnetic Mode | +| WTL | Wavelength Tunable Laser | + +## 5 Conventions + +Unless otherwise specified, use standard range of atmospheric conditions as per [IEC 60793-1-1]. + +## 6 Test methods + +Both reference test method (RTM) and alternative test methods (ATMs) are usually given here for each parameter, and it is the intention that both the RTM and the ATM(s) may be suitable for normal product acceptance purposes. However, when using an ATM, should any discrepancy arise, it is + +recommended that the RTM be employed as the technique for providing the definitive measurement results. + +NOTE – The apparatus and procedure given cover only the essential basic features of the test methods. It is assumed that the detailed instrumentation will incorporate all necessary measures to ensure stability, noise elimination, signal-to-noise ratio, etc. + +### 6.1 Test methods for the mode field diameter + +#### 6.1.1 Reference test method: The far-field scan + +##### 6.1.1.1 General + +The mode field diameter is determined from the far-field intensity distribution $F^2(\theta)$ , according to the definition given in clause 3.4.1.4. The integration limits are shown to be 0 and $\pi/2$ , but it is understood that this notation implies the truncation of the integrals in the limit of increasing argument. While the maximum physical value of the argument $\theta$ is $\pi/2$ , the integrands rapidly approach zero before this value is reached. The relative error in the determination of the mode field diameter, introduced by this truncation, is discussed in clause 6.1.1.2.6. + +##### 6.1.1.2 Test apparatus + +A schematic diagram of the test apparatus is shown in Figure 1. + +![Figure 1 – Typical arrangement of the far-field scan set-up. The diagram shows a light source connected to a specimen fiber. A cladding mode stripper is used to remove cladding modes. The far-field intensity distribution is measured by a detector at a distance d. The angle theta is indicated between the fiber axis and the detector. The detector is connected to a data acquisition system.](c67d21fb3d9042e88cdc669f071b4e7c_img.jpg) + +The diagram illustrates the experimental setup for a far-field scan. On the left, a 'Source' is connected to a 'Specimen' fiber. A 'Cladding mode stripper' is shown as a dashed box around the specimen. Light from the specimen is directed towards a 'Detector' on the right, which is connected to 'Data acquisition' equipment. The distance between the specimen and the detector is labeled 'd'. The angle between the fiber axis and the detector is labeled 'θ'. The detector is shown with two arrows pointing to it, representing the light rays. The text 'G.650.1(18)\_F01' is visible in the bottom right corner of the diagram. + +Figure 1 – Typical arrangement of the far-field scan set-up. The diagram shows a light source connected to a specimen fiber. A cladding mode stripper is used to remove cladding modes. The far-field intensity distribution is measured by a detector at a distance d. The angle theta is indicated between the fiber axis and the detector. The detector is connected to a data acquisition system. + +Figure 1 – Typical arrangement of the far-field scan set-up + +###### 6.1.1.2.1 Light source + +The light source should be stable in position, intensity and wavelength over a time period sufficiently long to complete the measurement procedure. The spectral characteristics of the source should be chosen to preclude multimode operation. The FWHM spectral width should be no greater than 10 nm. + +###### 6.1.1.2.2 Modulation + +It is customary to modulate the light source in order to improve the signal/noise ratio at the receiver. If such a procedure is adopted, the detector should be linked to a signal processing system synchronous with the source modulation frequency. The detecting system should have substantially linear sensitivity characteristics. + +###### 6.1.1.2.3 Launching conditions + +The launching conditions used should be sufficient to excite the fundamental ( $LP_{01}$ ) mode. For example, suitable launching techniques could be: + +- jointing with a fibre; +- launching with a suitable system of optics. + +Care should be taken that higher order modes do not propagate. For this purpose, it may be necessary to introduce a loop of suitable radius or another mode filter in order to remove higher order modes. For example, a one-turn bend with a radius of 30 mm on the fibre is generally sufficient for most ITU-T G.65x fibres. For some ITU-T G.657 fibres, smaller radius, multiple bends or longer sample lengths can be applied to remove high-order propagating modes. + +###### 6.1.1.2.4 Cladding mode stripper + +Precautions should be taken to prevent the propagation and detection of cladding modes. + +##### 6.1.1.2.5 Specimen + +The specimen should be a short length of the optical fibre to be measured. Primary fibre coating should be removed from the section of the fibre inserted in the mode stripper, if used. The fibre ends should be clean, smooth and perpendicular to the fibre axes. It is recommended that the end faces be flat and perpendicular to the fibre axes to within $1^\circ$ . + +###### 6.1.1.2.6 Scan apparatus + +A mechanism to scan the far-field intensity distribution should be used. The detector should be at least 10 mm from the fibre end, and the detector's active area should not subtend too large an angle in the far field. This can be assured by placing the detector at a distance from the fibre end greater than $K \cdot 2wb/\lambda$ , where $2w$ is the expected mode field diameter of the fibre to be measured, $b$ is the diameter of the active area of the detector, $\lambda$ is the wavelength, and $K$ is the resolution factor. + +The value of $K$ is recommended to be greater than 20. For accurate measurements, the dynamic range of the measurement should be greater than 50 dB. The maximum scan half-angle depends on the fibre type and should be chosen so that the far field scan is characterized down to 50 dB of the maximum signal. As an example, the maximum scan half-angle for fibre covered by [ITU-T G.652] is typically greater than $20^\circ$ . A suitable scan apparatus, relationship between $b$ and a distance to the detector, can be ensured for an arbitrary ITU-T G.65x fibre by satisfying the recommended $K$ and dynamic range values simultaneously. + +###### 6.1.1.2.7 Detector + +A suitable detector should be used. The detector should have linear sensitivity characteristics. Different detector types may be considered such as photodetector with pinhole, optical fibre, or lens. + +An effective $b$ value corresponds to the core, pinhole or lens diameter when a photodetector with optical fibre, pinhole or lens is used, respectively. These photodetectors can increase the $K$ by reducing a $b$ value, however they also require a smaller receive power sensitivity. + +###### 6.1.1.2.8 Amplifier + +An amplifier should be employed in order to increase the signal level. + +##### 6.1.1.2.9 Data acquisition + +The measured signal level should be recorded and suitably processed. + +##### 6.1.1.3 Measurement procedure + +The launch end of the fibre should be aligned with the launch beam, and the output end of the fibre should be aligned to the appropriate output device. + +The following procedure should be followed: by scanning the detector in fixed steps no greater than $0.5^\circ$ , the far-field intensity distribution, $F^2(\theta)$ , is measured, and the mode field diameter is calculated from Equation 3-2. + +##### 6.1.1.4 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement, dynamic range of the measurement system, processing algorithms, and a description of the scanning device used (including the scan angle and resolution factor $K$ ); +- b) launching conditions; +- c) wavelength and spectral line-width FWHM of the source; +- d) fibre identification and length; +- e) type of cladding mode stripper; +- f) description of high-order modes filter; +- g) type and dimensions of the detector; +- h) temperature of the sample and environmental conditions (when necessary); +- i) indication of the accuracy and repeatability; +- j) mode field diameter. + +#### 6.1.2 First alternative test method: The variable aperture technique + +##### 6.1.2.1 General + +The mode field diameter is determined from the complementary aperture transmission function $a(x)$ , ( $x = D \cdot \tan \theta$ being the aperture radius, and $D$ the distance between the aperture and the fibre): + +$$2w = (\lambda / \pi D) \left[ \int_0^\infty a(x) \frac{x}{(x^2 + D^2)^2} dx \right]^{-1/2} \quad (6-1)$$ + +The mathematical equivalence of equations 3-2 and 6-1 is valid in the approximation of small angles $\theta$ . Under this approximation, Equation 6-1 can be derived from Equation 3-2 by integration. + +##### 6.1.2.2 Test apparatus + +###### 6.1.2.2.1 Light source (as in clause 6.1.1.2.1) + +###### 6.1.2.2.2 Modulation (as in clause 6.1.1.2.2) + +###### 6.1.2.2.3 Launching conditions (as in clause 6.1.1.2.3) + +###### 6.1.2.2.4 Cladding mode stripper (as in clause 6.1.1.2.4) + +###### 6.1.2.2.5 Specimen (as in clause 6.1.1.2.5) + +###### 6.1.2.2.6 Aperture apparatus + +A mechanism containing at least twelve apertures spanning the half-angle range of numerical apertures from 0.02 to 0.25 (0.4 for fibres covered by [ITU-T G.653], [ITU-T G.655] and [ITU-T G.656]) should be used. Light transmitted by the aperture is collected and focused onto the detector. + +NOTE – The numerical apertures (NA) of the collecting optics should be large enough not to affect the measurement results. + +###### 6.1.2.2.7 Detector + +A suitable detector should be used. The detector should have linear sensitivity characteristics. + +###### 6.1.2.2.8 Amplifier (as in clause 6.1.1.2.8) + +##### 6.1.2.2.9 Data acquisition (as in clause 6.1.1.2.9) + +##### 6.1.2.3 Measurement procedure + +The launch end of the fibre should be aligned with the launch beam, and the output end of the fibre should be aligned to the appropriate output device. + +The following procedure should be followed: the power transmitted by each aperture, $P(x)$ , is measured, and the complementary aperture transmission function, $a(x)$ , is found as: + +$$a(x) = 1 - \frac{P(x)}{P_{\max}} \quad (6-2)$$ + +where $P_{\max}$ is the power transmitted by the largest aperture and $x$ is the aperture radius. The mode field diameter is computed from Equation 6-1. + +##### 6.1.2.4 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement, dynamic range of the measurement system, processing algorithms, and a description of the aperture assembly used (including the NA); +- b) launching conditions; +- c) wavelength and spectral line-width FWHM of the source; +- d) fibre identification and length; +- e) type of cladding mode stripper; +- f) description of high-order modes filter; +- g) type and dimensions of the detector; +- h) temperature of the sample and environmental conditions (when necessary); +- i) indication of the accuracy and repeatability; +- j) mode field diameter. + +#### 6.1.3 Second alternative test method: The near-field scan + +##### 6.1.3.1 General + +The mode field diameter is determined from the near-field intensity distribution $f^2(r)$ ( $r$ being the radial coordinate): + +$$2w = 2 \left[ 2 \frac{\int_0^\infty r f^2(r) dr}{\int_0^\infty r \left[ \frac{df(r)}{dr} \right]^2 dr} \right]^{1/2} \quad (6-3)$$ + +The mathematical equivalence of equations 3-2 and 6-3 is valid in the approximation of small angles $\theta$ . Under this approximation, the near-field $f(r)$ and the far-field $F(\theta)$ form a Hankel pair. By means of the Hankel transform, it is possible to pass from Equation 3-2 to Equation 6-3 and vice versa. + +##### **6.1.3.2 Test apparatus** + +###### **6.1.3.2.1 Light source (as in clause 6.1.1.2.1)** + +##### **6.1.3.2.2 Modulation (as in clause 6.1.1.2.2)** + +###### **6.1.3.2.3 Launching conditions (as in clause 6.1.1.2.3)** + +###### **6.1.3.2.4 Cladding mode stripper (as in clause 6.1.1.2.4)** + +###### **6.1.3.2.5 Specimen (as in clause 6.1.1.2.5)** + +###### **6.1.3.2.6 Scan apparatus** + +Magnifying optics (e.g., a microscope objective) should be employed to enlarge and focus an image of the fibre near field onto the plane of a scanning detector (for example, a scanning photodetector with a pinhole aperture or a scanning pig-tailed photodetector). The numerical aperture and magnification should be selected to be compatible with the desired spatial resolution. For calibration, the magnification of the optics should have been measured by scanning the length of a specimen whose dimensions are independently known with sufficient accuracy. + +###### **6.1.3.2.7 Detector (as in clause 6.1.2.2.7)** + +###### **6.1.3.2.8 Amplifier (as in clause 6.1.1.2.8)** + +##### **6.1.3.2.9 Data acquisition (as in clause 6.1.1.2.9)** + +##### **6.1.3.3 Measurement procedure** + +The launch end of the fibre should be aligned with the launch beam, and the output end of the fibre should be aligned to the appropriate output device. + +The following procedure should be followed: the near field of the fibre is enlarged by the magnifying optics and focused onto the plane of the detector. The focusing should be performed with maximum accuracy in order to reduce dimensional errors due to the scanning of a defocused image. The near-field intensity distribution, $f^2(r)$ , is scanned and the mode field diameter is calculated from Equation 6-3. Alternatively, the near-field intensity distribution $f^2(r)$ may be transformed into the far-field domain using a Hankel transform and the resulting transformed far-field $F^2(\theta)$ may be used to compute the mode field diameter from Equation 3-2. + +NOTE – Discriminate between the radial coordinate $r$ in the fibre end face and the radial coordinate $Mr$ of the scanning detector in the image plane, where $M$ is the magnification. + +##### **6.1.3.4 Presentation of the results** + +The following details should be presented: + +- a) test set-up arrangement, dynamic range of the measurement system, processing algorithms, and a description of the imaging and scanning devices used; +- b) launching conditions; +- c) wavelength and spectral line-width FWHM of the source; +- d) fibre identification and length; +- e) type of cladding mode stripper; +- f) description of high-order modes filter; +- g) magnification of the apparatus; +- h) type and dimensions of the detector; +- i) temperature of the sample and environmental conditions (when necessary); + +- j) indication of the accuracy and repeatability; +- k) mode field diameter. + +#### 6.1.4 Third alternative test method: Bidirectional backscatter difference + +##### 6.1.4.1 General + +The mode field diameter is determined from the difference in bidirectional backscatter across a splice with a dead-zone fibre with a known mode field diameter: + +$$w_s = w_d 10^{\frac{g(L_d - L_s) + f}{20}} \quad (6-4)$$ + +where: + +$w_d$ is the mode field diameter of the dead-zone fibre + +$w_s$ is the mode field diameter of the specimen fibre + +$L_d$ is the change in backscatter (dB) across the splice when measuring from the dead-zone fibre + +$L_s$ is the change in backscatter (dB) across the splice when measuring from the specimen fibre + +$g$ is a wavelength and fibre design dependent adjustment factor + +$f$ is a wavelength and fibre design dependent adjustment factor + +##### 6.1.4.2 Test apparatus + +These are as in clause 6.4.2.2, with the following additional requirements: + +Figure 2 shows a schematic diagram of an apparatus that uses an optical switch. The use of such apparatus is optional. + +![Schematic diagram of the optional apparatus for bidirectional backscatter. An OTDR is connected to an optical switch. The optical switch has two output paths. The top path goes through Dead-zone Fibre A to Splice A, which is connected to a Specimen fibre. The bottom path goes through Dead-zone Fibre B to Splice B, which is also connected to the same Specimen fibre. The Specimen fibre is terminated at the right end. The diagram is labeled G.650.1(18)_F02.](37819f1170c36655c57129b6bd8a5ceb_img.jpg) + +Schematic diagram of the optional apparatus for bidirectional backscatter. An OTDR is connected to an optical switch. The optical switch has two output paths. The top path goes through Dead-zone Fibre A to Splice A, which is connected to a Specimen fibre. The bottom path goes through Dead-zone Fibre B to Splice B, which is also connected to the same Specimen fibre. The Specimen fibre is terminated at the right end. The diagram is labeled G.650.1(18)\_F02. + +**Figure 2 – Optional apparatus for bidirectional backscatter** + +The optical time domain reflectometer source wavelength should be known to be within 2 nm. A shift of 2 nm will introduce error of about 0.02 μm for measurements at 1310 nm to 1550 nm. + +A dead-zone fibre should be long enough to prevent the dead-zone region from including the splice or butt-joint with the specimen fibre. The MFD of the dead-zone fibre should be measured for each wavelength for which measurements are needed with either the RTM or the first or second alternative methods. The dead-zone fibre is typically the same design as the fibre under test. + +The splice or butt-joint should be sufficiently stable over the time the measurement is completed so that the results are not affected. Index matching fluid is recommended when a butt-joint is used in order to minimize reflections. + +##### 6.1.4.3 Measurement procedure + +This procedure is in two parts: The first is the procedure for a given fibre and wavelength once the adjustment factors, $g$ and $f$ are known. The second is the procedure for qualifying a given fibre type and design at a given wavelength. The qualification procedure includes the accurate calculation of the adjustment factors, $g$ and $f$ , that allow correction for OTDR wavelength off nominal. Where $g$ and $f$ are unknown and accurate determination is impractical, nominal values of 1 and 0, respectively, may be assumed. + +###### 6.1.4.3.1 Measurement of a fibre at a given wavelength + +- Align the fibre so that light is launched from the dead-zone fibre A into the specimen fibre. (From the OTDR across splice A into the specimen fibre as shown in Figure 2). +- Measure the change in backscatter across the splice (splice A as shown in Figure 2), avoiding any reflection, and record the value as $L_d$ . +- Align the fibre so that light is launched from the specimen fibre into the dead-zone fibre A. (From the OTDR, across splice B into the specimen fibre, then across splice A in Figure 2). +- Measure the change in backscatter across the splice (splice A as shown in Figure 2), avoiding any reflection, and record the value as $L_s$ . +- Calculate the mode field diameter according to Equation 6-4. + +###### 6.1.4.3.2 Qualification for a fibre type, design and wavelength + +- Select a sample of fibres of the type and design to be measured, for which the mode field diameter, $w_s$ , has been measured at the desired wavelength using either the reference test method or the first or second alternative methods, so that the range of mode field diameter values for the fibre type and design are represented in the sample. +- Complete procedures a) to d) of clause 6.1.4.3.1 to determine the changes in backscatter across the splice $L_d$ and $L_s$ . +- Compute $20 \log_{10} \left( \frac{w_s}{w_d} \right)$ for each fibre and perform a linear regression of it versus $(L_d - L_s)$ to determine $g$ (slope) and $f$ (intercept). +- Select a second sample of fibres, independent from the first set to determine $g$ and $f$ , for which the mode field diameter has also been measured at the desired wavelength using either the reference test method or the first or second alternative methods. +- Complete the procedure in clause 6.1.4.3.1, using the values of $g$ and $f$ determined in c) to determine the mode field diameter, $w_s$ . Find the difference to the value measured with the reference test method or the first or second alternative methods. +- Calculate the average difference (bias), and the standard deviation of differences ( $\sigma_d$ ) to determine if equivalence has been demonstrated. +- An acceptable measure of equivalence may be obtained by calculating the equivalence level, $B$ , where $B = |\text{bias}| + 2 \sigma_d / \sqrt{n}$ , with $n$ being the sample size. A typical upper limit on $B$ is 0.1 $\mu\text{m}$ . +- If $B$ exceeds the upper limit, adjustments to the procedure such as improving the splice or butt-joint are recommended. + +##### 6.1.4.4 Presentation of results + +For each fibre measured the following details should be presented: + +- nominal wavelength; +- mode field diameter value; + +- c) fibre identification. + +Information to be available: + +- a) description of the apparatus; +- b) qualification data for each fibre type, design and wavelength; +- c) indication of accuracy and repeatability. + +### 6.2 Test methods for the cladding diameter, core concentricity error and cladding non-circularity + +#### 6.2.1 Reference test method: The near-field image technique + +##### 6.2.1.1 General + +The glass geometry parameters are determined from the near-field intensity distribution, according to the definitions given in clauses 3.3.3, 3.3.5 and 3.3.8. + +##### 6.2.1.2 Test apparatus + +![A schematic diagram of the test apparatus for the near-field image technique. On the left, a light source labeled L1 is connected to 'Launch optics'. An arrow points from the launch optics to a horizontal line representing the 'Fibre under test'. Above the fibre, a circle represents the core. At the right end of the fibre, there are two vertical rectangular blocks representing cladding mode strippers. To the right of the strippers, 'Magnifying optics' are shown, with an arrow pointing from them to a rectangular box labeled 'Camera'. Below the magnifying optics, another light source labeled L2 is shown with an arrow pointing towards the fibre end. The diagram is labeled G.650.1(18)_F03 in the bottom right corner.](b2ea162a0f53d5e0504b7d28346e0754_img.jpg) + +A schematic diagram of the test apparatus for the near-field image technique. On the left, a light source labeled L1 is connected to 'Launch optics'. An arrow points from the launch optics to a horizontal line representing the 'Fibre under test'. Above the fibre, a circle represents the core. At the right end of the fibre, there are two vertical rectangular blocks representing cladding mode strippers. To the right of the strippers, 'Magnifying optics' are shown, with an arrow pointing from them to a rectangular box labeled 'Camera'. Below the magnifying optics, another light source labeled L2 is shown with an arrow pointing towards the fibre end. The diagram is labeled G.650.1(18)\_F03 in the bottom right corner. + +Figure 3 – A scheme for the test apparatus + +###### 6.2.1.2.1 Light sources + +A light source, L1, for illuminating the core should be chosen, adjustable in intensity and stable in position, over a period of time which is sufficiently long to complete the measurement procedure. Wavelengths above and/or below the fibre's cut-off wavelength may be used. A second light source, L2, with similar characteristics, should be used to illuminate the cladding. + +###### 6.2.1.2.2 Launching conditions + +The launch optics should be arranged so that the light source uniformly overfills the fibre angularly and spatially. At the output end, the cladding should be illuminated uniformly. + +NOTE – The launching conditions from source L1 should be such so as to determine a circularly symmetric spatial field distribution at the output of the fibre. + +###### 6.2.1.2.3 Cladding mode stripper + +Cladding mode light should be stripped from the specimen near the input end. When the fibre under test has a primary coating with a refractive index higher than that of the glass, this coating acts as a cladding mode stripper. + +###### 6.2.1.2.4 Specimen + +The specimen should be a short length of the optical fibre to be measured. The fibre ends should be clean, smooth and perpendicular to the fibre axis. + +##### 6.2.1.2.5 Magnifying optics + +The magnifying optics should consist of an optical system (e.g., a microscope objective) which magnifies the specimen output near field, focusing it onto the plane of the detector. The numerical + +aperture and hence the resolving power of the optics should be compatible with the measuring accuracy required, and not lower than 0.3. The magnification should be selected to be compatible with the desired resolution, and should be recorded. + +##### **6.2.1.2.6 Detector** + +CCD video cameras, scanning vidicons, or other pattern/intensity recognition devices should be used to detect the magnified output near-field image and transmit it to a video monitor. The video digitizer performs the digitization of the image for further computer analysis. The video system should be sufficiently linear so that, after calibration, the measurement uncertainty is not greater than required. + +##### **6.2.1.2.7 Video image monitor** + +A video image monitor should be used to display the detected image. The screen on the monitor typically shows a pattern, such as cross-hairs, to assist the operator in centring the image of the specimen. Computer-controlled alignment and/or focusing may be used. + +##### **6.2.1.2.8 Data system** + +The measurement, data acquisitions and calculations are performed using a computer. A printer provides a hard copy of the information and measurement results. + +##### **6.2.1.3 Measurement procedure** + +###### **6.2.1.3.1 Calibration** + +Calibration should be according to the procedures given in [IEC 61745]. + +###### **6.2.1.3.2 Measurement** + +The prepared specimen should be aligned at the input end to achieve the launch condition specified. The near-field image of the output end should be focused and centred in the monitor. The intensity of the core image illumination at the input end and the intensity of the cladding image illumination at the output end should be adjusted according to an established, internal standard for the particular test equipment. + +The digitized video image of the output face should be recorded and the points representing both the cladding image edge and the core image edge should be determined and recorded in edge tables. The decision levels of the boundaries in the near-field image are the following: + +Core image boundary: This level should be chosen from 5% to 50% of the maximum near-field intensity. + +Cladding image boundary: Different methods for determining the cladding boundary can be used, depending on the illumination method. The method used in practice should be the same as that used in calibration. + +###### **6.2.1.3.3 Calculations** + +The raw data of the core and cladding edge are fitted to smooth, mathematically closed forms to determine best estimates of the actual edges. These smooth mathematically closed forms are then fitted to a circle in order to determine the geometrical characteristics, including the first order deviations from the ideal circular shape of each respective edge boundary. These values and the mathematical edge representation are used to determine the parameters as follows: + +- $X_{co}$ , $Y_{co}$ ( $\mu\text{m}$ ) fitted core centre; +- $R_{cl}$ ( $\mu\text{m}$ ) fitted cladding radius; +- $X_{cl}$ , $Y_{cl}$ ( $\mu\text{m}$ ) fitted cladding centre; +- $R_{mincl}$ ( $\mu\text{m}$ ) minimum distance of the cladding edge to centre; +- $R_{maxcl}$ ( $\mu\text{m}$ ) maximum distance of the cladding edge to centre; + +- cladding diameter ( $\mu\text{m}$ ) = $2R_{\text{cl}}$ ; +- cladding non-circularity (%) = $100(R_{\text{maxcl}} - R_{\text{mincl}})/R_{\text{cl}}$ ; +- core concentricity error ( $\mu\text{m}$ ) = $[(X_{\text{cl}} - X_{\text{co}})^2 + (Y_{\text{cl}} - Y_{\text{co}})^2]^{1/2}$ . + +The smooth mathematically closed forms used to represent the edges are required to allow a variation of curvature that is greater than or equal to that found in an ellipse. For non-elliptical forms, the data can be converted to polar coordinates about a roughly estimated centre before fitting the radius versus angular position. + +Active filtering, or removal of raw data points that represent cleave damage from those that are fitted to the mathematical form, is allowed. The choice of the curve, the equipment, the cleave method and the filtration algorithm are interactive in their contribution to the quality of the cladding measurement results. + +##### 6.2.1.4 Presentation of the results + +For each measurement the following details should be presented: + +- fibres identification; +- the parameters: cladding diameter, cladding non-circularity and core concentricity error. + +Information to be available: + +- test set-up arrangement; +- launching conditions; +- spectral characteristics; +- magnification factor; +- type and dimensions of the detector; +- indication of accuracy and repeatability, including calibration data. + +#### 6.2.2 First alternative test method: The refracted near-field technique + +##### 6.2.2.1 General + +The refracted near-field measurement gives directly the refractive index distribution across the entire fibre (core and cladding). The geometrical characteristics of the fibre can be obtained from the refractive index distribution using suitable algorithms. + +##### 6.2.2.2 Test apparatus + +A schematic diagram of the measurement method is shown in Figure 4. The technique involves the scanning of a focused spot of light across the end of the fibre. The launch optics are arranged to overfill the numerical aperture of the fibre. The fibre end is immersed in a fluid of slightly higher index than the cladding. Part of the light is guided down the fibre and the rest appears as a hollow cone outside the fibre. A disc is placed on the axis of the core to ensure that only refracted light reaches the detector. + +The optical resolution, and hence the ability to resolve details in the fibre geometry, depends on the size of the focused spot of light. This depends both on the numerical aperture of the focusing lens and on the size of the disc. However, the position of sharp features can be resolved to much better accuracy than this, dependent on step size for stepper motor systems, or position monitoring accuracy of analogue drives. + +![Figure 4 – Typical arrangement of the refracted near-field test set-up. The diagram shows a schematic of the optical setup. A laser source (represented by a circle with a horizontal line) emits a beam that passes through a quarter-wave plate. The beam then enters 'Launch optics', which focus it onto the 'Fibre under test'. The fibre is held in a 'Cell' containing a fluid, and a 'Disc' is positioned near the fibre's end. Light refracted from the fibre is collected by 'Collecting optics' and sent to a 'Detector'. The detector's output is amplified by an 'Amplifier' and then processed by 'Data acquisition' and a 'Computer'. The computer controls 'X-Y motors' (labeled 'M') that move the cell, and 'X-Y Electronic micrometres' (labeled 'μm') that measure the position. A feedback loop connects the computer back to the micrometres. The diagram is labeled 'G.650.1(18)_F04'.](7133ccf78043568ca62ecbcd43628a4a_img.jpg) + +Figure 4 – Typical arrangement of the refracted near-field test set-up. The diagram shows a schematic of the optical setup. A laser source (represented by a circle with a horizontal line) emits a beam that passes through a quarter-wave plate. The beam then enters 'Launch optics', which focus it onto the 'Fibre under test'. The fibre is held in a 'Cell' containing a fluid, and a 'Disc' is positioned near the fibre's end. Light refracted from the fibre is collected by 'Collecting optics' and sent to a 'Detector'. The detector's output is amplified by an 'Amplifier' and then processed by 'Data acquisition' and a 'Computer'. The computer controls 'X-Y motors' (labeled 'M') that move the cell, and 'X-Y Electronic micrometres' (labeled 'μm') that measure the position. A feedback loop connects the computer back to the micrometres. The diagram is labeled 'G.650.1(18)\_F04'. + +**Figure 4 – Typical arrangement of the refracted near-field test set-up** + +##### 6.2.2.2.1 Source + +A stable laser giving about 1 mW of power in the $TEM_{00}$ mode is required, such as a HeNe laser. + +A quarter-wave plate is introduced to change the beam from linear to circular polarization because the reflectivity of light at an air-glass interface is strongly angle and polarization-dependent. + +##### 6.2.2.2.2 Launching conditions + +The launch optics, which are arranged to overfill the numerical aperture of the fibre, bring a beam of light to a focus on the flat end of the fibre. The optical axis of the beam of light should be within $1^\circ$ of the axis of the fibre. The resolution of the equipment is determined by the size of the focused spot, which should be as small as possible in order to maximize the resolution, e.g., less than $1.0\ \mu\text{m}$ . The equipment enables the focused spot to be scanned across the fibre cross section. + +##### 6.2.2.2.3 Cell + +The cell will contain a fluid with a refractive index slightly higher than that of the fibre cladding. The position of the cell will be controlled by X-Y motors driven by the computer and detected by X-Y micrometres. + +##### 6.2.2.2.4 Detection + +The refracted light is collected by suitable collecting optics and brought to the detector in any convenient manner provided that all the refracted light is collected. By calculation, the required size of disc and its position along the central axis can be determined. + +##### 6.2.2.2.5 Data acquisition + +The measured intensity distribution can be recorded, processed and presented in a suitable form, according to the scanning technique and to the specification requirements. A computer will be used to drive the X-Y motors, to record the X-Y position of the cell and the corresponding power levels, and to process the measured data. + +##### 6.2.2.3 Procedure + +Refer to the schematic diagram of the test apparatus (Figure 4). + +###### 6.2.2.3.1 Preparation of fibre under test + +A length of fibre less than 2 m is required. + +The primary fibre coating should be removed from the section of fibre immersed in the fluid cell. + +The fibre ends should be clean, smooth and perpendicular to the fibre axis. + +###### **6.2.2.3.2 Equipment calibration** + +The equipment is calibrated with the fibre removed from the fluid cell. During the measurement, the angle of the cone of light varies according to the refractive index seen at the entry point to the fibre (hence the change of power passing the disc). With the fibre removed and the fluid index and cell thickness known, this change in angle can be simulated by translating the disc along the optic axis. By moving the disc to a number of predetermined positions, one can scale the profile in terms of relative index. Absolute index can only be found if the cladding or fluid index is known accurately at the measurement wavelength and temperature. + +More convenient calibration procedures can be performed by means of a thin rod of known constant refractive index or by means of a multimode-multistep fibre, where the various refractive index values are known with great accuracy. This latter technique can also be useful in checking the linearity of the apparatus. In this respect, it may also be useful to control the fluid temperature in the fluid cell. + +###### **6.2.2.3.3 Raster scan** + +The launch end of the fibre to be measured is immersed in the fluid cell and the laser beam is simultaneously centred and focused on the fibre end face. + +The disc is centred on the output cone. Refracted modes passing the disc are collected and focused onto the detector. + +The focused laser spot is scanned across the fibre end cross section and a two-dimensional distribution of fibre refractive index is directly obtained. From this distribution, the geometrical characteristics will be calculated. + +###### **6.2.2.3.4 Geometrical characteristics** + +Once the raster scan of refractive index is performed, the core contour is obtained taking the points at the core-cladding interface of refractive index coinciding with the mean value between the averaged refractive indices of core and cladding respectively. The cladding contour is determined in a similar way but at the cladding-index matching fluid interface. Geometry analyses consistent with the terms in clause 3 will be performed starting from the core and cladding contours data. An index profile measurement actually yields the core concentricity error. + +##### **6.2.2.4 Presentation of the results** + +The following details should be presented: + +- a) test set-up arrangement and indication of the scanning technique used; +- b) fibre identification; +- c) cladding diameter; +- d) core concentricity error; +- e) cladding non-circularity; +- f) core diameter (if required); +- g) raster scan across the entire fibre (if required); +- h) indication of accuracy and repeatability; +- i) temperature of the sample and environmental conditions (if necessary). + +#### **6.2.3 Second alternative test method: The side-view technique** + +##### **6.2.3.1 General** + +The side-view method is applied to single-mode fibres to determine geometrical parameters (core concentricity error, cladding diameter and cladding non-circularity) by measuring the intensity distribution of light that is refracted inside the fibre. + +##### 6.2.3.2 Test apparatus + +A schematic diagram of the test apparatus is shown in Figure 5. + +![Schematic diagram of side-view measurement system](a149b400127a3e3e50b3c98d27c5935c_img.jpg) + +The diagram illustrates the optical setup for side-view measurement. A light source emits light that passes through a collimator lens. The collimated beam is directed towards a test fibre. The test fibre is mounted on a stage that allows for fibre rotation and focus adjustment. The light refracted from the fibre is collected by magnifying optics. The magnified image is projected onto a detector, which is connected to a controller and a computer. The computer processes the data to generate an intensity distribution graph. The graph shows intensity on the y-axis and position along the fibre on the x-axis. The graph includes a central peak labeled 'c' and two side lobes labeled 'b'. The x-axis is marked with 'a' and 'a'' at the ends, and 'B' at the top right. The text 'Intensity distribution along a-a' in A' is written below the graph. The label 'G.650.1(18)\_F05' is in the bottom right corner. + +Schematic diagram of side-view measurement system + +**Figure 5 – Schematic diagram of side-view measurement system** + +###### 6.2.3.2.1 Light source + +The emitted light should be collimated, adjustable in intensity and stable in position, intensity and wavelength over a time period sufficiently long to complete the measuring procedure. A stable and high intensity light source such as a light emitting diode (LED) may be used. + +##### 6.2.3.2.2 Specimen + +The specimen to be measured should be a short length of single-mode fibre. The primary fibre coating should be removed from the observed section of the fibre. The surface of the fibre should be kept clean during the measurement. + +##### 6.2.3.2.3 Magnifying optics + +The magnifying optics should consist of an optical system (e.g., a microscope objective) which magnifies the intensity distribution of refracted light inside the fibre onto the plane of the scanning detector. The observation plane should be set at a fixed distance forward from the fibre axis. The magnification should be selected to be compatible with the desired spatial resolution and should be recorded. + +##### 6.2.3.2.4 Detector + +A suitable detector should be employed to determine the magnified intensity distribution in the observation plane along the line perpendicular to the fibre axis. A vidicon or charge coupled device can be used. The detector should have linear characteristics in the required measuring range. The detector's resolution should be compatible with the desired spatial resolution. + +##### 6.2.3.2.5 Data processing + +A computer with appropriate software should be used for the analysis of the intensity distributions. + +##### 6.2.3.3 Measurement procedure + +###### 6.2.3.3.1 Equipment calibration + +For equipment calibration, the magnification of the magnifying optics should be measured by scanning the length of a specimen whose dimensions are already known with suitable accuracy. This magnification should be recorded. + +###### 6.2.3.3.2 Measurement + +The test fibre is fixed in the sample holder and set in the measuring system. The fibre is adjusted so that its axis is perpendicular to the optical axis of the measuring system. + +Intensity distributions in the observation plane along the line perpendicular to the fibre axis (a-a' in A, in Figure 5) are recorded (shown as B) for different viewing directions, by rotating the fibre around its axis, keeping the distance between the fibre axis and the observation plane constant. The cladding diameter and the central position of the fibre are determined by analysing the symmetry of the radial intensity distribution in the magnified image (shown as b in B). The central position of the core is determined by analysing the intensity distribution of converged light (shown as c). The distance between the central position of the fibre and that of the core corresponds to the nominal observed value of core concentricity error. + +As shown in Figure 6, fitting the sinusoidal function to the experimentally obtained values of the mode field concentricity error (see Note 2 in clause 3.3.7) plotted as a function of the rotation angle, the actual core concentricity error is calculated as the product of the maximum amplitude of the sinusoidal function and magnification factor with respect to the lens effect due to the cylindrical structure of the fibre. The cladding diameter is evaluated as an averaged value of measured fibre diameters at each rotation angle, resulting in values for maximum and minimum diameters to determine the value of cladding non-circularity according to the definition. + +![Figure 6: A plot showing the measured value of the mode field concentricity error (MFCE) in micrometers (μm) as a function of the rotation angle in degrees. The y-axis ranges from -1 to +1 μm, and the x-axis ranges from 0 to 360 degrees. The data points (marked with 'x') follow a sinusoidal pattern, and a smooth curve is fitted to them. The curve crosses the zero line at 90 and 270 degrees, and reaches its minimum at 180 degrees. The label 'G.650.1(18)_F06' is present in the bottom right corner of the plot area.](b7cad3053c9ae57f0e6160f540c871fa_img.jpg) + +| Rotation angle (degree) | Actual measured value of MFCE (μm) | +|-------------------------|------------------------------------| +| 0 | 0.5 | +| 45 | 0.2 | +| 90 | 0.0 | +| 135 | -0.5 | +| 180 | -0.8 | +| 225 | -0.5 | +| 270 | 0.0 | +| 315 | 0.5 | +| 360 | 0.5 | + +Figure 6: A plot showing the measured value of the mode field concentricity error (MFCE) in micrometers (μm) as a function of the rotation angle in degrees. The y-axis ranges from -1 to +1 μm, and the x-axis ranges from 0 to 360 degrees. The data points (marked with 'x') follow a sinusoidal pattern, and a smooth curve is fitted to them. The curve crosses the zero line at 90 and 270 degrees, and reaches its minimum at 180 degrees. The label 'G.650.1(18)\_F06' is present in the bottom right corner of the plot area. + +**Figure 6 – Measured value of the mode field concentricity error as a function of rotation angle** + +##### 6.2.3.4 Presentation of the results + +The following details should be presented: + +- test arrangement; +- fibre identification; +- spectral characteristics of the source; +- indication of repeatability and accuracy; +- plot of nominal core concentricity error versus rotation angle; +- core concentricity error, cladding diameter and cladding non-circularity; + +g) temperature of the sample and environmental conditions (if necessary). + +#### 6.2.4 Third alternative test method: The transmitted near-field technique + +##### 6.2.4.1 General + +The geometrical parameters are determined from the near-field intensity distribution according to the definitions given in clauses 3.3.3, 3.3.5 and 3.3.8. + +Since mode field concentricity is a good approximation of core concentricity, this method can be used to evaluate core concentricity error. + +##### 6.2.4.2 Test apparatus + +A schematic diagram of the test apparatus is shown in Figure 7. + +![Schematic diagram of the transmitted near-field set-up. The diagram shows a light source connected to launch optics, which are connected to a mode filter. The mode filter is connected to a cladding mode stripper. The cladding mode stripper is connected to a fibre. The fibre is connected to magnifying optics, which are connected to a detector. The detector is connected to an amplifier, which is connected to a data acquisition unit. The diagram is labeled with components: Source, Launch optics, Mode filter, Cladding mode stripper, Fibre, Magnifying optics, Detector, Amplifier, and Data acquisition. Footnotes a) and b) are provided below the diagram.](55136bc716146672fc680fa05989f1d2_img.jpg) + +a) When appropriate +b) Including image shearing optics, where appropriate + +G.650.1(18)\_F07 + +Schematic diagram of the transmitted near-field set-up. The diagram shows a light source connected to launch optics, which are connected to a mode filter. The mode filter is connected to a cladding mode stripper. The cladding mode stripper is connected to a fibre. The fibre is connected to magnifying optics, which are connected to a detector. The detector is connected to an amplifier, which is connected to a data acquisition unit. The diagram is labeled with components: Source, Launch optics, Mode filter, Cladding mode stripper, Fibre, Magnifying optics, Detector, Amplifier, and Data acquisition. Footnotes a) and b) are provided below the diagram. + +Figure 7 – Typical arrangement of the transmitted near-field set-up + +###### 6.2.4.2.1 Light source + +A nominal 1310 nm (for fibres covered by [ITU-T G.652]) or 1550 nm (for fibres covered by [ITU-T G.653] and [ITU-T G.654]) light source for illuminating the core should be used. The light source should be adjustable in intensity and stable in position, intensity and wavelength over a time period sufficiently long to complete the measurement procedure. The spectral characteristics of this source should be chosen to preclude multimode operation. A second light source with similar characteristics can be used, if necessary, for illuminating the cladding. The spectral characteristics of the second light source should not cause defocusing of the image. + +###### 6.2.4.2.2 Launching conditions + +The launch optics, which will be arranged to overfill the fibre, will bring a beam of light to a focus on the flat input end of the fibre. + +##### 6.2.4.2.3 Mode filter + +In the measurement, it is necessary to assure single-mode operation at the measurement wavelength. In these cases, it may be necessary to introduce a bend in order to remove the LP11 mode. + +###### 6.2.4.2.4 Cladding mode stripper + +A suitable cladding mode stripper should be used to remove the optical power propagating in the cladding. When measuring the geometrical characteristics of the cladding only, the cladding mode stripper should not be present. + +##### 6.2.4.2.5 Specimen + +The specimen should be a short length of the optical fibre to be measured. The fibre ends should be clean, smooth and perpendicular to the fibre axis. + +##### **6.2.4.2.6 Magnifying optics** + +The magnifying optics should consist of an optical system (e.g., a microscope objective) which magnifies the specimen output near field, focusing it onto the plane of the scanning detector. The numerical aperture, and hence the resolving power of the optics, should be compatible with the measuring accuracy required, and not lower than 0.3. The magnification should be selected to be compatible with the desired spatial resolution, and should be recorded. + +##### **6.2.4.2.7 Detector** + +A suitable detector should be employed which provides the point-to-point intensity of the transmitted near-field pattern(s). For example, any of the following techniques can be used: + +- a) scanning photodetector with pinhole aperture; +- b) scanning mirror with fixed pinhole aperture and photodetector; +- c) scanning vidicon, charge coupled devices or other pattern/intensity recognition devices. + +The detector should be linear (or should be linearized) in behaviour over the range of intensities encountered. + +##### **6.2.4.2.8 Amplifier** + +An amplifier may be employed in order to increase the signal level. The bandwidth of the amplifier should be chosen according to the type of scanning used. When scanning the output end of the fibre with mechanical or optical systems, it is customary to modulate the optical source. If such a procedure is adopted, the amplifier should be linked to the source modulation frequency. + +##### **6.2.4.2.9 Data acquisition** + +The measured intensity distribution can be recorded, processed and presented in a suitable form, according to the scanning technique and to the specification requirements. + +##### **6.2.4.3 Measurement procedure** + +###### **6.2.4.3.1 Equipment calibration** + +For equipment calibration, the magnification of the magnifying optics should be measured by scanning the image of a specimen whose dimensions are already known with suitable accuracy. + +This magnification should be recorded. + +###### **6.2.4.3.2 Measurement** + +The launch end of the fibre should be aligned with the launch beam, and the output end of the fibre should be aligned to the optical axis of the magnifying optics. For transmitted near-field measurement, the focused image(s) of the output end of the fibre should be scanned by the detector, according to the specification requirements. The focusing should be performed with maximum accuracy, in order to reduce dimensional errors due to the scanning of a defocused image. The desired geometrical parameters are then calculated according to the definitions. + +Algorithms for defining edges and calculating the geometrical parameters are under study. + +#### **6.2.4.4 Presentation of the results** + +The following details should be presented: + +- a) test set-up arrangement, with indication of the scanning technique used; +- b) launching conditions; +- c) spectral characteristics of the source(s); +- d) fibre identification and length; +- e) type of mode filter (if applicable); + +- f) magnification of the magnifying optics; +- g) type and dimensions of the scanning detector; +- h) temperature of the sample and environmental conditions (when necessary); +- i) indication of the accuracy and repeatability; +- j) resulting dimensional parameters, such as cladding diameters, cladding non-circularities, core concentricity error, etc. + +### **6.3 Test methods for the cut-off wavelength** + +#### **6.3.1 Reference test method for the fibre cut-off wavelength ( $\lambda_c$ ) of the primary coated fibre: The transmitted power technique** + +##### **6.3.1.1 General** + +The cut-off wavelength measurement of single-mode fibres is intended to assure effective single-mode operation above a specified wavelength. + +The cut-off wavelength measurement should use the transmitted power technique which measures the variation with wavelength of the transmitted power of a short length of the fibre under test, under defined conditions, compared to a reference transmitted power. There are two possible ways to obtain this reference power: + +- a) the test fibre with a loop of smaller radius; or +- b) a short (1-2 m) length of multimode fibre. + +NOTE 1 – In this version of this Recommendation, the ATM for $\lambda_c$ measurement found in the previous version are incorporated in an RTM. + +NOTE 2 – The presence of a primary coating on the fibre usually does not affect the cut-off wavelength. However, the presence of a secondary coating may result in a cut-off wavelength that may be significantly shorter than that of the primary coated fibre. + +The measurement may be performed on a fibre having a secondary coating if the secondary coating type has been examined and it has been confirmed that it does not significantly affect the cut-off wavelength, provided that the secondary coating is properly applied. + +##### **6.3.1.2 Test apparatus** + +##### **6.3.1.2.1 Light source** + +A light source with a line width not exceeding 10 nm (FWHM), stable in position, intensity and wavelength over a time period which is sufficient to complete the measurement procedure, and capable of operating over a sufficient wavelength range, should be used. + +##### **6.3.1.2.2 Modulation** + +It is customary to modulate the light source in order to improve the signal/noise ratio at the receiver. If such a procedure is adopted, the detector should be linked to a signal processing system synchronous with the source modulation frequency. The detecting system should be substantially linear. + +##### **6.3.1.2.3 Launching conditions** + +The launching conditions should be used in such a way as to excite substantially and uniformly both LP01 and LP11 modes. For example, suitable launching techniques could be: + +- a) jointing with a multimode fibre; or +- b) launching with a suitable large spot-large NA optics. + +##### 6.3.1.2.4 Cladding mode stripper + +The cladding mode stripper is a device that encourages the conversion of cladding modes to radiation modes; as a result, cladding modes are stripped from the fibre. Care should be taken to avoid affecting the propagation of the $LP_{11}$ mode. + +##### 6.3.1.2.5 Optical detector + +A suitable detector should be used so that all of the radiation emerging from the fibre is intercepted. The spectral response should be compatible with the spectral characteristics of the source. The detector should be uniform and have linear sensitivity. + +#### 6.3.1.3 Measurement procedure + +###### 6.3.1.3.1 Standard test sample + +The measurement should be performed on a 2 m length of fibre. The fibre is inserted into the test apparatus and bent to form a loosely constrained loop. The loop should complete one full turn of a circle of 140 mm radius or a full turn (360 degrees) consisting of two arcs (180 degrees each) of 140 mm radius, connected by tangents (split mandrel configuration). The remaining part of the fibre should be substantially free of external stresses. While some incidental bends of larger radii are permissible, they should not introduce a significant change in the measurement result. The output power $P_1(\lambda)$ should be recorded versus $\lambda$ in a sufficiently wide range around the expected cut-off wavelength. + +In split mandrel configuration as shown in Figure 8, the lower semicircular mandrel moves to take any slack from the fibre loop without requiring movement of the launch or receive optics or placing the fibre sample under any significant tension. + +![Diagram of fibre deployment for cut-off wavelength measurement using the split-mandrel technique. A fibre is shown between a 'Launch' unit and a 'Receive' unit. The fibre forms a loop around a mandrel. The mandrel is split into two semicircular halves, each with a radius of 140 mm. The top half is fixed, and the bottom half is movable, as indicated by a vertical double-headed arrow. The fibre is tangent to the horizontal sections of the mandrel and follows the semicircular arcs. The diagram is labeled 'G.650.1(18)_F08'.](f0b7abcb093621bb310bf61fbe0f0d2d_img.jpg) + +The diagram illustrates the split-mandrel configuration for fibre deployment. A fibre is shown between a 'Launch' unit and a 'Receive' unit. The fibre forms a loop around a mandrel. The mandrel is split into two semicircular halves, each with a radius of 140 mm. The top half is fixed, and the bottom half is movable, as indicated by a vertical double-headed arrow. The fibre is tangent to the horizontal sections of the mandrel and follows the semicircular arcs. The diagram is labeled 'G.650.1(18)\_F08'. + +Diagram of fibre deployment for cut-off wavelength measurement using the split-mandrel technique. A fibre is shown between a 'Launch' unit and a 'Receive' unit. The fibre forms a loop around a mandrel. The mandrel is split into two semicircular halves, each with a radius of 140 mm. The top half is fixed, and the bottom half is movable, as indicated by a vertical double-headed arrow. The fibre is tangent to the horizontal sections of the mandrel and follows the semicircular arcs. The diagram is labeled 'G.650.1(18)\_F08'. + +**Figure 8 – Fibre deployment: Cut-off wavelength by the split-mandrel technique** + +##### 6.3.1.3.2 Transmission through the reference sample + +Either method a) or b) may be used. + +- a) Using the test sample, and keeping the launch conditions fixed, an output power $P_2(\lambda)$ is measured over the same wavelength range with at least one loop of sufficiently small radius in the test sample to filter the $LP_{11}$ mode. The exact value of the smaller radius may be determined prior to measurement. It should be small enough to attenuate the second-order mode but not the primary mode, but not too small in order to avoid macrobending effects at higher wavelengths. A radius between 10 and 30 mm is typical for most ITU-T G.65x fibres. + +For some ITU-T G.657 fibres, the radius should be much smaller, and this measurement procedure may not be adequate for these fibres. See Note 2. + +- b) With a short (1-2 m) length of multimode fibre, an output power $P_3(\lambda)$ is measured over the same wavelength range. + +NOTE 1 – The presence of leaky modes may cause ripple in the transmission spectrum of the multimode reference fibre, affecting the result. To reduce this problem, light-launching conditions may be restricted to fill only 70% of the multimode fibre's core diameter and NA or a suitable mode filter may be used. + +NOTE 2 – For some ITU-T G.657 fibres, because of the bending-loss insensitive nature of these fibres, method a) may not be adequate, it is recommended to use method b) as a reference scan for these fibres. + +##### 6.3.1.3.3 Calculations + +The spectral attenuation of the test specimen, relative to the reference power is: + +$$a(\lambda) = 10 \log \frac{P_1(\lambda)}{P_i(\lambda)} \quad (6-5)$$ + +where $i = 2$ or $3$ for methods a) or b), respectively, in clause 6.3.1.3.2. + +Assuming a straight-line representation of the upper wavelength region, the deviation of higher-order modes from the fundamental mode is: + +$$\Delta a(\lambda) = a(\lambda) - (A_u + B_u \lambda) \quad (6-6)$$ + +$A_u$ and $B_u$ are determined so that $(A_u + B_u \lambda)$ represents the portion of the spectral attenuation curve at wavelengths above the region where the attenuation of higher order modes is accelerated (transition region). For method a), both $A_u$ and $B_u$ may be set to zero. See Figures 9a and 10a. + +NOTE – In method a) in clause 6.3.1.3.2, the small mode filter fibre loop eliminates all modes except the fundamental one for wavelengths greater than a few tens of nm below the cut-off wavelength $\lambda_c$ . For wavelengths more than several hundred nm above $\lambda_c$ , even the fundamental mode may be strongly attenuated by the loop. $a(\lambda)$ is equal to the logarithmic ratio between the total power emerging from the sample, including the $LP_{11}$ mode power, and the fundamental mode power. When the modes are uniformly excited in accordance with clause 6.3.1.2.3, $a(\lambda)$ then also yields the $LP_{11}$ mode attenuation $A(\lambda)$ in dB in the test sample: + +$$A(\lambda) = 10 \log \left[ \left( \frac{P_1(\lambda)}{P_2(\lambda)} - 1 \right) / 2 \right] \quad (6-7)$$ + +##### 6.3.1.3.4 Determination of cut-off wavelength + +In the transition region, higher-order mode power is reduced with increasing wavelength. Fibre cut-off wavelength, $\lambda_c$ , is defined as the wavelength at which the higher-order mode power relative to the fundamental mode power, $\Delta a(\lambda)$ , has been reduced to 0.1 dB. + +Figures 9b and 10b illustrate "humps" that sometimes appear near the cut-off wavelength. In the absence of humps (see Figures 9a and 10a), accurate determination of $\lambda_c$ can be achieved without algorithms. Optionally, for precision improvement, fitting algorithms based on the following equations can be used when humps are present. Appendix I contains examples of such algorithms. + +$$\gamma(\lambda) = 10 \log \left[ -\frac{10}{A} \log \left( \frac{10^{\Delta a(\lambda)/10} - 1}{\rho} \right) \right] \quad (6-8)$$ + +$$A = 10 \log \left[ \rho / (10^{0.01} - 1) \right] \quad (6-9)$$ + +Unless otherwise specified, $\rho = 2$ . (6-10) + +When the coefficients of: + +$$A_t + B_t \lambda = -Y(\lambda) \quad (6-11)$$ + +are determined for wavelengths in the transition region, then: + +$$\lambda_c = -\frac{A_t}{B_t} \quad (6-12)$$ + +![Figure 9a: Single-mode reference cut-off plot. The graph shows Attenuation (dB) on the y-axis versus Wavelength (μm) on the x-axis. The plot is divided into 'Trans' and 'Upper' regions by a vertical dashed line. A dashed curve rises to a peak in the 'Trans' region and then drops sharply. A solid curve follows the dashed curve and drops to a constant low level at the 'Cut-off 1188 nm' point, marked by a vertical line. The label 'G.650.1(18)_F09a' is in the bottom right corner.](7848a2560bb726462c09c09bf727d81d_img.jpg) + +Figure 9a: Single-mode reference cut-off plot. The graph shows Attenuation (dB) on the y-axis versus Wavelength (μm) on the x-axis. The plot is divided into 'Trans' and 'Upper' regions by a vertical dashed line. A dashed curve rises to a peak in the 'Trans' region and then drops sharply. A solid curve follows the dashed curve and drops to a constant low level at the 'Cut-off 1188 nm' point, marked by a vertical line. The label 'G.650.1(18)\_F09a' is in the bottom right corner. + +**Figure 9a – Single-mode reference cut-off plot** + +![Figure 9b: Single-mode reference cut-off plot with humps. The graph shows Attenuation (dB) on the y-axis versus Wavelength (μm) on the x-axis. The plot is divided into 'Trans' and 'Upper' regions by vertical dashed lines. A dashed curve rises to a peak in the 'Trans' region and then drops sharply. A solid curve follows the dashed curve and drops to a constant low level at the 'Cut-off 1218 nm' point, marked by a vertical line. Beyond the cut-off, the solid curve exhibits oscillations labeled 'Humps'. The label 'G.650.1(18)_F09b' is in the bottom right corner.](54b5c00e104d6abae06037df2ce1f075_img.jpg) + +Figure 9b: Single-mode reference cut-off plot with humps. The graph shows Attenuation (dB) on the y-axis versus Wavelength (μm) on the x-axis. The plot is divided into 'Trans' and 'Upper' regions by vertical dashed lines. A dashed curve rises to a peak in the 'Trans' region and then drops sharply. A solid curve follows the dashed curve and drops to a constant low level at the 'Cut-off 1218 nm' point, marked by a vertical line. Beyond the cut-off, the solid curve exhibits oscillations labeled 'Humps'. The label 'G.650.1(18)\_F09b' is in the bottom right corner. + +**Figure 9b – Single-mode reference cut-off plot with humps** + +![Figure 10a: Multimode reference cut-off plot. The graph shows Attenuation (dB) on the y-axis versus Wavelength (μm) on the x-axis. It is divided into 'Trans' and 'Upper' regions by a vertical dashed line. A solid curve shows a sharp drop to a minimum at the 'Cut-off 1232 nm' (marked by a vertical dashed line). A dashed line represents the asymptotic trend. The plot is labeled G.650.1(18)_F10a.](24b549c0c4b79c515b244625cf4f4978_img.jpg) + +Figure 10a: Multimode reference cut-off plot. The graph shows Attenuation (dB) on the y-axis versus Wavelength (μm) on the x-axis. It is divided into 'Trans' and 'Upper' regions by a vertical dashed line. A solid curve shows a sharp drop to a minimum at the 'Cut-off 1232 nm' (marked by a vertical dashed line). A dashed line represents the asymptotic trend. The plot is labeled G.650.1(18)\_F10a. + +**Figure 10a – Multimode reference cut-off plot** + +![Figure 10b: Multimode reference cut-off plot with hump. Similar to Figure 10a, but the solid curve exhibits a 'Hump' (a local maximum) just before the main minimum at the 'Cut-off 1182 nm'. The plot is labeled G.650.1(18)_F10b.](03498c9b76f980b32f2dfbb7c2e539d2_img.jpg) + +Figure 10b: Multimode reference cut-off plot with hump. Similar to Figure 10a, but the solid curve exhibits a 'Hump' (a local maximum) just before the main minimum at the 'Cut-off 1182 nm'. The plot is labeled G.650.1(18)\_F10b. + +**Figure 10b – Multimode reference cut-off plot with hump** + +NOTE – According to the definition, the LP11 mode attenuation in the test sample is 19.3 dB at the cut-off wavelength. + +##### 6.3.1.4 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement; +- b) launching condition; + +- c) type of reference sample; +- d) temperature of the sample and environmental conditions (if necessary); +- e) fibre identification; +- f) wavelength range of measurement; +- g) fibre cut-off wavelength; +- h) plot of $\alpha(\lambda)$ (if required); +- i) interpolation method (if used). + +#### **6.3.2 Reference test method for the cable cut-off wavelength ( $\lambda_{cc}$ ): The transmitted power technique** + +##### **6.3.2.1 General** + +This cut-off wavelength measurement, which is performed on cabled single-mode fibres in a deployment condition which simulates outside plant minimum cable lengths, is intended to assure effective single-mode operation above a specified wavelength. + +The transmitted power technique uses the variation with wavelength of the transmitted power of the fibre cable under test, under defined conditions, compared to a reference transmitted power. There are two possible ways to obtain this reference power: + +- a) the cabled test fibre with a loop of smaller radius; +- b) a short (1-2 m) length of multimode fibre. + +NOTE – In this version of this Recommendation, the ATM for $\lambda_{cc}$ measurement found in the previous version is incorporated in an RTM. + +##### **6.3.2.2 Test apparatus** + +##### **6.3.2.2.1 Light source (as in clause 6.3.1.2.1)** + +##### **6.3.2.2.2 Modulation (as in clause 6.3.1.2.2)** + +##### **6.3.2.2.3 Launching conditions (as in clause 6.3.1.2.3)** + +##### **6.3.2.2.4 Cladding mode stripper (as in clause 6.3.1.2.4)** + +##### **6.3.2.2.5 Optical detector (as in clause 6.3.1.2.5)** + +##### **6.3.2.3 Measurement procedure** + +###### **6.3.2.3.1 Standard test sample** + +The measurement should be performed on a length of single-mode fibre in a cable. A cable length of 22 m should be prepared by exposing 1 m uncabled fibre length at each end, and the resulting 20 m cabled portion should be laid without any small bends which could affect the measurement value. To simulate the effects of a splice organizer, one loop of $X = 40$ mm radius should be applied to each uncabled fibre length (see Figure 11). The uncabled fibre is deployed with secondary coating (if present) intact. While some incidental bends of larger radii are permissible in the fibre or cable, they should not introduce a significant change in the measurements. The output power $P_1(\lambda)$ should be recorded versus $\lambda$ in a sufficiently wide range around the expected cut-off wavelength. + +Alternatively, uncabled single-mode fibre in a deployment condition can be used as a test sample which assures that the results for $\lambda_{cc}$ are in agreement with those achieved in measurements conducted on cabled fibres. + +A fibre length of 22 m is inserted into the test apparatus; the inner 20 m are bent to form loosely constrained loops of a radius $r \geq 140$ mm. One loop of $X = 40$ mm radius should be applied to each fibre end (see Figure 12). + +Though the relationship between $\lambda_{cc}$ values measured with cabled and uncabled fibre samples depends on the specific cable design, $\lambda_{cc}$ measured with an uncabled fibre sample is generally higher than that measured with a cabled fibre sample. + +NOTE 1 – The loops are intended to simulate deployment conditions. + +NOTE 2 – Two loops of $X = 40$ mm radius at one end can be substituted for one loop at each end. + +NOTE 3 – $\lambda_{cc}$ measurement using a cabled or uncabled test sample found in clause 6.3.2 is described in Annex B or Annex A in [IEC 60793-1-44], respectively. + +![Figure 11: Deployment condition for measurement of lambda_cc on cabled fibre. The diagram shows a cable with a central 20 m straight section and two loops at each end. Each loop has a radius of 2X and is included in a 1 m segment. The cable is labeled 'Cable' and the diagram is identified by 'G.650.1(18)_F11'.](08c7a76a7786bd08b99dd4cb41583ef4_img.jpg) + +Figure 11: Deployment condition for measurement of lambda\_cc on cabled fibre. The diagram shows a cable with a central 20 m straight section and two loops at each end. Each loop has a radius of 2X and is included in a 1 m segment. The cable is labeled 'Cable' and the diagram is identified by 'G.650.1(18)\_F11'. + +**Figure 11 – Deployment condition for measurement of $\lambda_{cc}$ on cabled fibre** + +![Figure 12: Deployment condition for measurement of lambda_cc on uncabled fibres. The diagram shows a 22 m fibre with a central section of n loops having a radius of 2r, and two end loops, each with a radius of 2X and labeled '1 loop'. The fibre is labeled '22 m fibre' and the diagram is identified by 'G.650.1(18)_F12'.](fb18a83d10ebdad8e3e5ea2e86b36136_img.jpg) + +Figure 12: Deployment condition for measurement of lambda\_cc on uncabled fibres. The diagram shows a 22 m fibre with a central section of n loops having a radius of 2r, and two end loops, each with a radius of 2X and labeled '1 loop'. The fibre is labeled '22 m fibre' and the diagram is identified by 'G.650.1(18)\_F12'. + +**Figure 12 – Deployment condition for measurement of $\lambda_{cc}$ on uncabled fibres** + +##### 6.3.2.3.2 Transmission through the reference sample (as in clause 6.3.1.3.2) + +##### 6.3.2.3.3 Calculations + +The logarithmic ratio between the transmitted powers $P_1(\lambda)$ and $P_i(\lambda)$ is calculated as: + +$$R(\lambda) = 10 \log \frac{P_1(\lambda)}{P_i(\lambda)} \quad (6-13)$$ + +where $i = 2$ or $3$ for methods a) or b) in clause 6.3.1.3.2, respectively. + +##### 6.3.2.3.4 Determination of cabled fibre cut-off wavelength + +The calculations and method of determining cable cut-off wavelength, $\lambda_{cc}$ , are the same as for fibre cut-off wavelength. See clauses 6.3.1.3.3 and 6.3.1.3.4. + +#### 6.3.2.4 Presentation of the results + +The following details should be presented: + +- test set-up arrangement; +- launching condition; +- type of reference sample; +- temperature of the sample and environmental conditions (if necessary); +- fibre and cable identification; + +- f) wavelength range of measurement; +- g) cabled fibre cut-off wavelength; +- h) plot of $R(\lambda)$ (if required); +- i) value of fibre loop radius $r$ (only for uncabled test sample). + +### **6.4 Test methods for attenuation** + +The attenuation tests are intended to provide a means whereby a certain attenuation value may be assigned to a fibre length so that individual attenuation values may be added together to determine the total attenuation of a concatenated length. + +#### **6.4.1 Reference test method: The cut-back technique** + +##### **6.4.1.1 General** + +The cut-back technique is a direct application of the definition in which the power levels $P_1$ and $P_2$ are measured at two points of the fibre without a change of input conditions. $P_2$ is the power emerging from the far end of the fibre, and $P_1$ is the power emerging from a point near the input after cutting the fibre. + +##### **6.4.1.2 Test apparatus** + +Measurements may be made at one or more spot wavelengths, or alternatively, a spectral response may be required over a range of wavelengths. Diagrams of suitable test equipment, to obtain one loss or the loss spectrum measurements respectively, are shown as examples in Figure 13. + +![Diagram (a) showing the arrangement of test equipment to make one loss measurement. A light source connected to a bias circuit feeds into a launching system. The output passes through a mode filter and a cladding mode stripper. A cut is made in the fibre, followed by the fibre on test. After the fibre, another cladding mode stripper is used, followed by a detector. The detector output is amplified and sent to a level measurement unit.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +Diagram (a) illustrates the setup for a single loss measurement. It begins with a **Light source** connected to a **Bias circuit**. The light is coupled into a **Launching system**, which then passes through a **Mode filter** and a **Cladding mode stripper**. A cut is made in the fibre, followed by the **Fibre on test**. After the fibre, another **Cladding mode stripper** is used, followed by a **Detector**. The detector's output is processed by an **Amplifier** and finally a **Level measurement** unit. + +Diagram (a) showing the arrangement of test equipment to make one loss measurement. A light source connected to a bias circuit feeds into a launching system. The output passes through a mode filter and a cladding mode stripper. A cut is made in the fibre, followed by the fibre on test. After the fibre, another cladding mode stripper is used, followed by a detector. The detector output is amplified and sent to a level measurement unit. + +a) Arrangement of test equipment to make one loss measurement + +![Diagram (b) showing the arrangement of test equipment used to obtain the loss spectrum measurement. A halogen lamp feeds into a monochromator. The output passes through a launching system, a cladding mode stripper, a mode filter, and a cut in the fibre. The fibre on test is followed by another cladding mode stripper and a detector. The detector output is processed by a lock-in amplifier, which also receives a reference signal from a light modulator. The output of the lock-in amplifier is sent to a controller and a plotter. The diagram is labeled G.650.1(18)_F13.](47a7beddcb8a1b7abdca746967e32bb4_img.jpg) + +Diagram (b) shows the setup for obtaining a loss spectrum measurement. A **Halogen lamp** is coupled into a **Mono-chromator**. The output passes through a **Launching system**, a **Cladding mode stripper**, and a **Mode filter**. A cut is made in the fibre, followed by the **Fibre on test**. After the fibre, another **Cladding mode stripper** is used, followed by a **Detector**. The detector's output is processed by a **Lock-in amplifier**, which also receives a **Reference signal** from a **Light modulator**. The output of the lock-in amplifier is sent to a **Controller** and a **Plotter**. The diagram is labeled **G.650.1(18)\_F13**. + +Diagram (b) showing the arrangement of test equipment used to obtain the loss spectrum measurement. A halogen lamp feeds into a monochromator. The output passes through a launching system, a cladding mode stripper, a mode filter, and a cut in the fibre. The fibre on test is followed by another cladding mode stripper and a detector. The detector output is processed by a lock-in amplifier, which also receives a reference signal from a light modulator. The output of the lock-in amplifier is sent to a controller and a plotter. The diagram is labeled G.650.1(18)\_F13. + +b) Arrangement of test equipment used to obtain the loss spectrum measurement + +**Figure 13 – The cut-back technique** + +##### 6.4.1.2.1 Optical source + +A suitable radiation source should be used as a lamp, laser or light emitting diode. The choice of source depends upon the type of measurement. The source should be stable in position, intensity and wavelength over a time period sufficiently long to complete the measurement procedure. The spectral line width (FWHM) should be specified so that the line width is narrow compared with any features of the fibre spectral attenuation. + +##### 6.4.1.2.2 Modulation + +It is customary to modulate the light source in order to improve the signal/noise ratio at the receiver. If such a procedure is adopted, the detector should be linked to a signal processing system synchronous with the source modulation frequency. The detecting system should be substantially linear in sensitivity. + +##### **6.4.1.2.3 Launching conditions** + +The launching conditions used should be sufficient to excite the fundamental mode. For example, suitable launching techniques could be: + +- a) jointing with a fibre; +- b) launching with a suitable system of optics. + +##### **6.4.1.2.4 Mode filter** + +Care should be taken that higher order modes do not propagate through the cut-back length. In these cases, it may be necessary to introduce a bend in order to remove the higher modes. For example, a one-turn bend with a radius of 30 mm on the fibre is generally sufficient for most ITU-T G.65x fibres. For some ITU-T G.657 fibres, smaller radius, multiple bends or longer sample length can be applied to remove high-order propagating modes. + +##### **6.4.1.2.5 Cladding mode stripper** + +A cladding mode stripper encourages the conversion of cladding modes to radiation modes; as a result, cladding modes are stripped from the fibre. + +##### **6.4.1.2.6 Optical detector** + +A suitable detector should be used so that all of the radiation emerging from the fibre is intercepted. The spectral response should be compatible with spectral characteristics of the source. The detector should be uniform and have linear sensitivity characteristics. + +##### **6.4.1.3 Measurement procedure** + +###### **6.4.1.3.1 Preparation of fibre under test** + +Fibre ends should be substantially clean, smooth and perpendicular to the fibre axis. Measurements on uncabled fibres should be carried out with the fibre loose on the drum, i.e., microbending effects should not be introduced by the drum surface. + +##### **6.4.1.3.2 Procedure** + +- 1) The fibre under test is placed in the measurement set-up. The output power $P_2$ is recorded. +- 2) Keeping the launching conditions fixed, the fibre is cut to the cut-back length (for example, 2 m from the launching point). The cladding mode stripper, when needed, is refitted and the output power $P_1$ from the cut-back length is recorded. +- 3) The attenuation of the fibre, between the points where $P_1$ and $P_2$ have been measured, can be calculated, using $P_1$ and $P_2$ , from the definition equations 3-4 and 3-5. + +##### **6.4.1.4 Presentation of the results** + +The following details should be presented: + +- a) test set-up arrangement, including source type, source wavelength, and line width (FWHM); +- b) fibre identification; +- c) length of sample; +- d) description of high-order modes filter; +- e) attenuation of the sample quoted in dB; +- f) attenuation coefficient quoted in dB/km; +- g) indication of accuracy and repeatability; +- h) temperature of the sample and environmental conditions (if necessary). + +#### **6.4.2 First alternative test method: The backscattering technique** + +##### **6.4.2.1 General** + +A test method for the attenuation coefficient of single-mode optical fibre based on bidirectional backscattering measurements is described. This technique can also be applied to check the attenuation uniformity, optical continuity, physical discontinuities, splice losses and the length of the fibre. + +Unidirectional backscattering measurements can be adopted in particular cases, e.g., verification of the backscatter slope variation in cabled fibres. + +Procedures for the calibration of backscattering equipment (for single-mode fibres) are provided in [IEC 61746-1]. + +##### **6.4.2.2 Test apparatus** + +##### **6.4.2.2.1 General considerations** + +The signal level of the backscattered optical signal will normally be small and close to the noise level. In order to improve the signal-to-noise ratio and the dynamic measuring range, it is therefore customary to use a high power light source in connection with signal processing of the detected signal. In addition, adjustment of the pulse width may be required to obtain a compromise between resolution and dynamic range. + +Care should be taken that higher order modes do not propagate. + +An example of apparatus is shown in Figure 14a. + +##### **6.4.2.2.2 Optical source** + +Use a stable, high power optical source of appropriate wavelengths and record them. The pulse width and repetition rate should be consistent with the desired resolution and the length of the fibre. + +##### **6.4.2.2.3 Optical coupling system** + +An optical system for an efficient coupling of the beam into the fibre under test, the branching device or the optical detector should be used. Various devices, such as index matching materials, can be added to reduce Fresnel reflections. + +##### **6.4.2.2.4 Branching device** + +A branching device is needed to couple the source radiation into the fibre and the backscattered radiation onto the detector, while avoiding a direct source-detector coupling. Avoid using devices with polarization-dependent properties. + +![Schematic of apparatus for the backscattering technique. An optical source is connected to an optical coupling system, which is connected to a branching device. The branching device is connected to an optical coupling system, which is connected to a fibre under test. The fibre under test is connected to an optical coupling system, which is connected to an optical detector. The optical detector is connected to an amplifier, which is connected to a signal processor. The signal processor is connected to an oscilloscope and a data acquisition system.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +``` + +graph LR + OS[Optical source] --> OCS1[Optical coupling system] + OCS1 --> BD[Branching device] + BD --> OCS2[Optical coupling system] + OCS2 --> F[Fibre under test] + F --> OCS3[Optical coupling system] + OCS3 --> OD[Optical detector] + OD --> AMP[Amplifier] + AMP --> SP[Signal processor] + SP --> OSC[Oscilloscope] + SP --> DAS[Data acquisition system] + +``` + +Schematic of apparatus for the backscattering technique. An optical source is connected to an optical coupling system, which is connected to a branching device. The branching device is connected to an optical coupling system, which is connected to a fibre under test. The fibre under test is connected to an optical coupling system, which is connected to an optical detector. The optical detector is connected to an amplifier, which is connected to a signal processor. The signal processor is connected to an oscilloscope and a data acquisition system. + +a) Schematic of apparatus + +![Example of a unidirectional backscattering loss curve. The graph shows Power in dB on the y-axis and Length on the x-axis. The curve starts at a high power level (1), drops sharply (2), then gradually decreases (3), has a small step (4), and finally rises to a peak (5) before dropping off.](1c2028183a35357e7238438a4af9cab7_img.jpg) + +G.650.1(18)\_F14 + +Example of a unidirectional backscattering loss curve. The graph shows Power in dB on the y-axis and Length on the x-axis. The curve starts at a high power level (1), drops sharply (2), then gradually decreases (3), has a small step (4), and finally rises to a peak (5) before dropping off. + +b) Example of a unidirectional backscattering loss curve + +**Figure 14 – The backscattering technique** + +##### 6.4.2.2.5 Optical detector + +A detector should be used so that the maximum possible backscattered power is intercepted. The detector response should be compatible with the levels and wavelengths of the detected signal. A substantially linear detector response is required for attenuation measurements. + +##### 6.4.2.2.6 Amplifier + +A suitable amplifier should follow the optical detector, so that the signal level becomes adequate for signal processing. The amplifier bandwidth should involve a trade-off between time resolution and noise reduction. + +##### 6.4.2.2.7 Signal processor + +A signal processor able to improve the signal-to-noise ratio, to calculate the attenuation curve from the two unidirectional backscattering loss curves, and to provide a logarithmic response in the detection system is required. An oscilloscope for a direct view of the backscattering trace and a data acquisition system to store the measurement results can be connected to the signal processor. + +##### 6.4.2.2.8 Cladding mode stripper + +See clause 6.4.1.2.5. + +##### 6.4.2.2.9 Fibre sample configuration + +The measurement may be made with the fibre in a number of fibre configurations (e.g., as cabled fibre, on a suitable shipping spool or as required for the reference text method). + +##### 6.4.2.3 Measurement procedure + +- Align the fibre under test to the optical coupling system. +- Measure two unidirectional backscattering loss curves, one from each end of the fibre. Figure 14b shows an example of such a unidirectional curve. Each backscattering loss curve is analysed by the signal processor and recorded on a logarithmic scale, avoiding the parts at the two ends of the curves, due to the reflections of the coupling and branching devices and by the fibre ends (see parts 1) and 5) in Figure 14b). +- Evaluate the length, $L_f$ , of the fibre from the time interval between the two ends of the backscattering loss curve, $T_f$ , and the group delay index, $N$ , of the fibre as: $L_f = c \cdot T_f / N$ ( $c$ being the free space light speed). +- Obtain the bidirectional backscattering loss curve using the two measured and recorded unidirectional backscattering loss curves, according to the procedure outlined in the following: + +Let $a(x)$ and $b(z)$ be the functions describing the two unidirectional backscattering loss curves expressed in dB, with $x$ and $z$ being the distances from the fibre ends nearest the respective launch site. The bidirectional backscattering loss curve is given by: + +$$y(x) = \frac{a(x) - b(L_f - x)}{2} \quad (6-14)$$ + +- Obtain the end-to-end fibre attenuation coefficient according to the procedure outlined in the following: + +The attenuation coefficient, $A(x_0, x_1)$ , for a fibre segment defined by the end positions $x_0$ and $x_1$ (with $x_0 < x_1$ ) is given by: + +$$A(x_0, x_1) = \frac{y(x_0) - y(x_1)}{x_1 - x_0} \quad (6-15)$$ + +This expression may be evaluated by a least squares linear fit of the data between $x_0$ and $x_1$ . The end-to-end fibre attenuation coefficient is determined in the same way as Equation 6-15 with the data points as close as possible to the end positions. However, these points should be outside the dead zone area and the end reflection area (see Figure 14b, areas 1) and 5)). + +##### 6.4.2.4 Presentation of the results + +The following details should be presented: + +- test set-up arrangement; +- kind of signal processing used; +- date of test; +- test specimen identification and length; +- pulse width; +- test wavelength(s); +- end-to-end fibre attenuation coefficient in dB/km; +- bidirectional backscattering loss curve. + +NOTE – Unidirectional backscattering measurements are obtained with the function $a(x)$ alone. The complete analysis of the recorded unidirectional backscattering loss curves (Figure 14b) shows that, independently from + +the attenuation measurements, many phenomena can be monitored using the backscattering technique including: + +- 1) reflection originated by the branching and coupling devices at the input end of the fibre; +- 2) zone of invariant backscattered slope; +- 3) discontinuity due to local defect, splice or coupling; +- 4) backscattering slope variation with length; +- 5) fluctuation at the output end of the fibre; +- 6) attenuation change, for example, with temperature. + +#### **6.4.3 Second alternative test method: The insertion loss technique** + +##### **6.4.3.1 General** + +The insertion loss technique consists of the evaluation of the power loss due to the insertion of the fibre under test between a launching and a receiving system, previously interconnected (reference condition). The powers $P_1$ and $P_2$ are thus evaluated in a less straightforward way than in the cut-back method. Therefore, this method is not intended for use on factory lengths of fibres and cables. + +The insertion loss technique is less accurate than a cut-back one, but has the advantage of being non-destructive for the fibre under test and for the semi-connectors possibly fixed at both ends. Therefore, it is particularly suitable for field use, and mainly intended for use with connectorized cable lengths. + +Two options are considered in the following for this technique (see Figure 15); they differ in the nature of the launching and receiving systems, as outlined below. Measurement conditions in between option a) and b) are possible and are discussed in Note 2 to clause 6.4.3.3.2. + +In option a), the quality of the semi-connectors possibly fixed to the fibre under test (and in general the quality of the used interconnection devices) influences the results; in option b), this influence is nearly excluded. As a consequence, option b) has in general a better accuracy, and it is more suitable when the actual attenuation of the fibre alone is needed. Conversely, when the fibre section under test is fitted with semi-connectors and has to be cascaded with other elements, the results from option a) are more meaningful, as they take into account the deviation of the semi-connectors from the nominal loss. + +![Figure 15: Typical arrangements for the insertion loss technique. The diagram shows two options, (a) and (b), for measuring insertion loss. Option (a) shows a 'Reference condition' setup where a light source (with bias and/or modulation) is connected to a launching system, which is then connected to a mode filter (MF) and a cladding mode stripper. This is followed by a connector (1) leading to the 'Fibre under test'. The fibre under test is connected to another connector (2), which leads to another mode filter (MF) and cladding mode stripper, which then connects to a detector and a measurement system. Option (b) shows a 'Reference system' setup where the light source and launching system are connected directly to the 'Fibre under test'. The output of the fibre under test is connected to a detector and a measuring system. Below these, a separate diagram shows a mode filter (MF) and cladding mode stripper connected between two connectors.](e8e818455bb0d1a6153299a388b94868_img.jpg) + +**Option a)** + +G.650.1(18)\_F15 + +**Option b)** + +Figure 15: Typical arrangements for the insertion loss technique. The diagram shows two options, (a) and (b), for measuring insertion loss. Option (a) shows a 'Reference condition' setup where a light source (with bias and/or modulation) is connected to a launching system, which is then connected to a mode filter (MF) and a cladding mode stripper. This is followed by a connector (1) leading to the 'Fibre under test'. The fibre under test is connected to another connector (2), which leads to another mode filter (MF) and cladding mode stripper, which then connects to a detector and a measurement system. Option (b) shows a 'Reference system' setup where the light source and launching system are connected directly to the 'Fibre under test'. The output of the fibre under test is connected to a detector and a measuring system. Below these, a separate diagram shows a mode filter (MF) and cladding mode stripper connected between two connectors. + +**Figure 15 – Typical arrangements for the insertion loss technique** + +##### 6.4.3.2 Test apparatus + +The schematic diagram of the test apparatus is shown in Figure 15. Measurements may be made at one or more wavelengths, or alternatively, a spectral response may be required over a range of wavelengths. + +##### 6.4.3.2.1 Optical source + +A suitable intensity stable radiation source should be used, such as a lamp, a laser or a light emitting diode. If a broad spectrum source is used, it should be followed by a wavelength selection device (alternatively this device can be inserted before the detector). In every case, the nominal wavelength of the source (possibly taking into account the wavelength selection device) should be known. + +The spectral width (FWHM) should be narrow compared with any features of the fibre spectral attenuation. + +##### **6.4.3.2.2 Modulation** + +See clause 6.4.1.2.2. + +##### **6.4.3.2.3 Launching conditions** + +###### **For option a)** + +The source is coupled to a short length of single-mode fibre having the same nominal characteristics of the fibre under test and equipped with a mode filter and a cladding mode stripper (see below). + +The above single-mode fibre is coupled to the fibre under test with a very precise coupling device to minimize coupling losses and ensure meaningful results. If the fibre under test is equipped with a semi-connector, a compatible high quality semi-connector should be fixed to the launching fibre. + +###### **For option b)** + +The source is coupled through a suitable optic to the fibre under test in such a way that the launched spot at the fibre input-end face has a near-field and a far-field intensity almost uniform within the mode field diameter and the far-field intensity of the fibre under test. + +The system can employ lenses and a fibre positioner; alternatively, the light can be launched in a step-index multimode fibre to be connected to the fibre under test. + +This is accomplished with any coupling device or a semi-connector compatible with those terminating the fibre under test. + +##### **6.4.3.2.4 Reference system (option b) only)** + +This system is composed of a short length of single-mode fibre having the same nominal characteristics of the fibre under test. The fibre is equipped with a mode filter and a cladding mode stripper; both devices should not introduce any loss on the fundamental mode. + +##### **6.4.3.2.5 Mode filter** + +The mode filter should allow the propagation along the fibre of the fundamental mode only. It can be implemented by a suitable bending condition on the fibre. For example, a one-turn bend with a radius of 30 mm on the fibre is generally sufficient for most ITU-T G.65x fibres. For some ITU-T G.657 fibres, a smaller radius, multiple bends or longer sample lengths can be applied to remove high-order propagating modes. + +##### **6.4.3.2.6 Cladding mode stripper** + +A cladding mode stripper encouraging the conversion of cladding modes to radiation modes should be employed. This device is not necessary if the fibre itself does not allow the propagation cladding modes. + +##### **6.4.3.2.7 Optical detection** + +The spectral response of the optical detector should be compatible with the spectral characteristics of the source. It should have linear sensitivity characteristics. + +###### **For option a)** + +The detector is connected to a single-mode fibre having the same nominal characteristics of the fibre under test. The fibre should be equipped with a mode filter and a cladding mode stripper. + +For the coupling with the fibre under test, the same indication as in clause 6.4.3.2.3, option a), is used. + +###### **For option b)** + +The end of the fibre under test is positioned in front of the detector. + +A suitable detector should be used so that all the radiation emerging from the fibre is intercepted. The detector should be spatially uniform. + +Alternatively, the detector is connected to a step-index multimode fibre. This fibre is coupled to the fibre under test by any coupling device or a semi-connector compatible with those terminating the fibre under test. + +##### 6.4.3.3 Measurements procedure + +###### 6.4.3.3.1 Preparation of fibre under test + +See clause 6.4.1.3.1. + +If the fibre is fitted with connectors, an appropriate cleaning procedure is required. + +##### 6.4.3.3.2 Procedure + +- 1) Once a measurement wavelength is selected, the power $P_1$ is firstly measured in the following way: + +###### For option a) + +The fibre of the launching system is connected to the fibre of the receiving system. The received power $P_1$ is then recorded. + +###### For option b) + +The reference system is connected between the launching and the receiving systems. The received power $P_1$ is then recorded. + +- 2) Successively, the fibre under test is connected between the launching and the receiving systems. The received power $P_2$ is then recorded. +- 3) Finally, the attenuation $A$ of the fibre section is calculated in the following way: + +###### For option a) + +$$A = 10 \log \frac{P_1(\lambda)}{P_2(\lambda)} + C_r - C_1 - C_2 \text{ (dB)} \quad (6-16a)$$ + +where $C_r$ , $C_1$ , and $C_2$ are the nominal average losses (in dB) of the connections respectively in the reference conditions at the input of the fibre under test and at its output. + +###### For option b) + +$$A = 10 \log \frac{P_1(\lambda)}{P_2(\lambda)} \text{ (dB)} \quad (6-16b)$$ + +NOTE 1 – The use of option b) assumes that the fibre under test does not allow the propagation to the receiving end of modes other than the fundamental one. + +NOTE 2 – Fibre attenuation measurements are also possible with a hybrid test set-up, using a launching system as in option a) and a receiving system as in option b), or vice versa. + +The measurement procedure for $P_1$ is in both cases similar to the one listed above for option a); no reference system is required and the launching system is connected directly to the receiving system. + +In both cases the fibre section attenuation can be calculated as: + +$$A = 10 \log \frac{P_1(\lambda)}{P_2(\lambda)} - C_a \text{ (dB)} \quad (6-17)$$ + +where $C_a$ is the nominal average loss (in dB) of the connection between the fibre under test and that part of the test set-up (launch or receive) belonging to option a). + +NOTE 3 – The intrinsic capability of option a) to evaluate the semi-connectors behaviour does not imply its use whenever this evaluation is required. + +Alternative possibilities are in using, even at an end where the semi-connector evaluation is required, an option b) set-up, previously connecting a single-mode cord to the fibre under test. The nominal loss of the fibre-to-cord connector is to be subtracted from the measured loss. + +The test apparatus to be used in practice should be chosen to minimize the error sources, taking into account the available instrumentation and connecting devices. The use of a hybrid set-up (a-launch, b-receive) plus a cord at the receiving end is usually the best solution when both the semi-connectors have to be evaluated. + +##### 6.4.3.4 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement, including source type, source wavelength, spectral width (FWHM) used for the measurement and the option type a) or b); +- b) fibre identification; +- c) length of the fibre section and end conditions (presence of semi-connectors); +- d) description of high-order modes filter; +- e) attenuation of the section quoted in dB; +- f) attenuation coefficient quoted in dB/km; +- g) indication of accuracy and repeatability (the connection loss repeatability should be taken properly into account); +- h) temperature of the sample and environmental conditions (if necessary). + +#### 6.4.4 Third alternative test method: Spectral attenuation modelling + +##### 6.4.4.1 General + +The attenuation coefficient of a fibre across a spectrum of wavelengths may be calculated by means of a characterizing matrix, $M$ , and a vector, $v$ . The vector contains the measured attenuation coefficients of a small number (three to five) of wavelengths (e.g., 1310 nm, 1360 nm, 1380 nm, 1410 nm, 1550 nm, and/or 1625 nm). + +In one approach, the fibre or cable supplier should provide a matrix characteristic of its product, and the modelled spectral attenuation is a vector, $w$ , calculated from the product of $M$ and $v$ : + +$$w = M \cdot v$$ + +Alternatively, if using a generic matrix, the supplier should provide a correction-factor vector so that the prediction equation becomes: + +$$W = w + e$$ + +where: + +$W$ is the modified vector + +$w$ comes from $w = M \cdot v$ + +$e$ is the correction-factor vector + +A generic matrix is a characterizing matrix which can be applied to a variety of fibres, designs and suppliers (presumably within a single fibre type), and which is determined and/or invoked by a standards body, single customer/end-user, or other industry source to which individual suppliers can compare their products, the difference being resolved by the vector, $e$ . + +##### 6.4.4.2 Test apparatus + +Since this technique involves a calculation using previously determined values, there is no specific apparatus required. Any of the recommended test methods (clause 6.4.1 the cut-back technique; clause 6.4.2 the backscattering technique; clause 6.4.3 the insertion loss technique) may be used to generate the measured values upon which the calculations are made. + +Direct measurements of attenuation take precedence over this method and is a case of conflict. + +##### 6.4.4.3 Calculation procedure + +The attenuation coefficient of a fibre across a spectrum of wavelengths may be calculated from $w = M \cdot v$ . The vector, $v$ , contains the measured attenuation coefficients of a small number (three to five) of predictor wavelengths (e.g., 1310 nm, 1360 nm, 1380 nm, 1410 nm, 1550 nm, and/or 1625 nm) which were measured using one of the previous attenuation test methods. Multiplying the matrix, $M$ , times the vector, $v$ , yields another vector, $w$ , which contains the predicted attenuation coefficients at many wavelengths (such as at 10 nm wavelength intervals from 1240 nm to 1600 nm). + +The matrix, $M$ , is given by: + +$$\begin{bmatrix} A_{11} & A_{12} & \dots & A_{1n} \\ A_{21} & A_{22} & \dots & A_{2n} \\ " & " & & \\ " & " & & \\ " & " & & \\ A_{m1} & A_{m2} & \dots & A_{mn} \end{bmatrix}$$ + +where $m$ is the number of wavelengths where the attenuation coefficients have to be estimated, and $n$ is the number of predictor wavelengths. An example of such a matrix is given for illustrative purposes in Appendix III. + +The standard deviation of the difference between the actual and predicted attenuation coefficients at each wavelength is to be less than 0,xx dB/km within a stated wavelength range. A different tolerance – 0,yy dB/km – may be necessary if an additional wavelength range is specified. The values of (xx) and (yy), and the wavelength range(s) should be agreed upon between the user and the manufacturer. + +If the estimate is obtained by using the supplier's specific matrix, $M$ , then no correction vector, $e$ , is necessary. + +Since the elements of both $M$ and $e$ are achieved on a statistical basis, the $w$ vector elements should be determined as statistical. To indicate the accuracy of the predicted attenuation coefficients, the fibre suppliers should give a vector containing the standard deviation of the differences between the actual and predicted attenuation coefficients, together with $M$ and/or $e$ (see clause 6.4.4.4). + +NOTE 1 – In order to facilitate use of this matrix, the fibre should be routinely measured at the predictor wavelengths. The predictor wavelengths should number from 3 to 5, for fibres operating over a wide range of wavelengths (such as ITU-T G.652 fibres modelled over 1260 – 1625 nm), with a strong preference given to the lower number if sufficient accuracy can be achieved. In cases where the model needs to function over a much narrower wavelength range (such as ITU-T G.654 fibres modelled over 1530 – 1625 nm), two predictor wavelengths might be adequate. In all cases the suitability of the choice of predictor wavelengths should be verified by showing sufficient accuracy compared to exact measurement. + +NOTE 2 – This model considers only uncabled fibre attenuation. An additional vector should be added to $w$ to take account of cabling effects and environmental effects. + +##### 6.4.4.4 Presentation of the results + +In addition to the items to be reported for the test method used in measuring the attenuation coefficients, report the following items: + +- a) the predicted attenuation and corresponding wavelength; +- b) the method used to obtain the measured attenuation coefficient values (if requested); +- c) the matrix used to predict the spectral attenuation, or the correction vector if a standard matrix was used (if requested); +- d) the vector containing the standard deviation of the differences between the actual and predicted attenuation coefficients obtained during the development of the matrix (if requested). + +### 6.5 Test methods for chromatic dispersion + +Chromatic dispersion varies with wavelength. Some methods and implementations measure the group delay as a function of wavelength and the chromatic dispersion and dispersion slope are deduced from the derivatives (with respect to wavelength) of this data. This differentiation is most often done after the data has been fitted to a mathematical model. Other implementations of the reference method can allow direct measurement at each of the required wavelengths. + +For some categories of fibre, the chromatic dispersion attributes are specified with the parameters of a specific model. In these cases, the relevant Recommendation defines the model appropriate for the definition of the specified parameters. For other fibre categories, the dispersion is specified to be within a given range for one or more specified wavelength intervals. In the latter case, either direct measurements may be made at the wavelength extremes or a fitting model may be used to either allow group delay measurement methods or implementations, or to allow the storage of a reduced set of parameters that may be used to calculate the interpolated dispersion for particular wavelengths which may not have actual direct measurement values. + +Annex A gives a general description of chromatic dispersion fitting and outlines a number of fitting equations suitable for use with any of the measurement methods or fibre categories. + +Appendix V gives the interferometric technique for chromatic dispersion measurement. + +#### 6.5.1 Reference test method: The phase-shift technique + +##### 6.5.1.1 General + +The fibre chromatic dispersion coefficient is derived from the measurement of the relative group delay experienced by the various wavelengths during propagation through a known length of fibre. + +The group delay is measured in the frequency domain, by detecting, recording and processing the phase shift of a sinusoidal modulating signal. + +The chromatic dispersion may be measured at a fixed wavelength or over a wavelength range. + +NOTE – Differential phase shift is documented in [IEC 60793-1-42], Annex C. + +##### 6.5.1.2 Test apparatus + +A schematic diagram of the test apparatus is shown in Figure 16. + +![Figure 16 – Typical arrangement of the test apparatus. The diagram shows a signal path starting from 'Source(s)' through a 'Signal generator', a 'Fibre' with a 'Cladding mode stripper', a 'Wavelength selector' (marked 'a) When needed'), a 'Photodetector', and a 'Delay detector' to a 'Signal processor computer'. A 'Reference channel' is shown below, starting from the 'Signal generator', through a 'Time delay' block, to the 'Delay detector'. The output of the 'Delay detector' is labeled 'Signal channel'.](dbd074feb5cce1300f42f91da8f673d1_img.jpg) + +G.650.1(18)\_F16 + +Figure 16 – Typical arrangement of the test apparatus. The diagram shows a signal path starting from 'Source(s)' through a 'Signal generator', a 'Fibre' with a 'Cladding mode stripper', a 'Wavelength selector' (marked 'a) When needed'), a 'Photodetector', and a 'Delay detector' to a 'Signal processor computer'. A 'Reference channel' is shown below, starting from the 'Signal generator', through a 'Time delay' block, to the 'Delay detector'. The output of the 'Delay detector' is labeled 'Signal channel'. + +**Figure 16 – Typical arrangement of the test apparatus** + +###### 6.5.1.2.1 Optical source + +The optical source should be stable in position, intensity and wavelength over a time period sufficiently long to complete the measurement procedure. Laser diodes, (laser diode array (LD-array)), wavelength tunable laser diodes (WTL) (e.g., an external cavity laser (ECL)), LEDs or broadband sources, (e.g., an Nd:YAG laser with a Raman fibre) may be used, depending on the wavelength range of the measurement. + +In any case, the modulating signal should be such as to guarantee a sufficient time resolution in the group delay measurement. + +##### 6.5.1.2.2 Wavelength selection + +The wavelength selector and monitoring are used to select and monitor the wavelength at which the group delay is to be measured. As a wavelength selector, an optical switch, a monochromator, dispersive devices, optical filters, optical couplers, connectors may be used, depending on the type of light sources and measurement set-up. The selection may be carried out by switching electrical driving signals for different wavelength light sources. + +The wavelength monitoring may be carried out by an optical fibre coupler and a wavelength meter. The wavelength selector and monitor may be used either at the input or at the output end of the fibre under test. + +If a mathematical fit is made to the data, at least one data point should be within 100 nm of $\lambda_0$ . + +##### 6.5.1.2.3 Detector + +The light emerging from the fibre under test, the reference fibre or the optical divider, etc., is coupled to a photodetector whose signal-to-noise ratio and time resolution are adequate for the measurement. The detector is followed by a low noise amplifier if needed. + +##### 6.5.1.2.4 Reference channel + +The reference channel may consist of an electrical signal line or optical signal line. A suitable time delay generator may be interposed in this channel. In certain cases, the fibre under test itself can be used as the reference channel line. + +##### 6.5.1.2.5 Delay detector + +The delay detector should measure the phase shift between the reference signal and the channel signal. A vector voltmeter could be used. + +##### 6.5.1.2.6 Signal processor + +A signal processor can be added in order to reduce the noise and/or the jitter in the measured waveform. If needed, a digital computer can be used for purposes of equipment control, data acquisition and numerical evaluation of the data. + +##### 6.5.1.3 Measurement procedure + +The fibre under test is suitably coupled to the source and to the detector through the wavelength selector or the optical divider, etc. If needed, a calibration of the chromatic delay of the source may be performed. A suitable compromise between wavelength resolution and signal level should be achieved. Unless the fibre under test is also used as the reference channel line, the temperature of the fibre should be sufficiently stable during the measurement. + +The phase shift between the reference signal and the channel signal at the operating wavelength are to be measured by the delay detector. Data processing appropriate to the type of modulation is used in order to obtain the chromatic dispersion coefficient at the operating wavelength. When needed, a spectral scan of the group delay versus wavelength can be performed; from the measured values a fitting curve can be completed. + +The time group delay will be deduced from the corresponding phase shift $\phi$ through the relation $\tau = \phi/(2\pi f)$ , $f$ being the modulation frequency. + +##### 6.5.1.4 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement; +- b) type of modulation used; +- c) source characteristics; +- d) fibre identification and length; +- e) characteristics of the wavelength selector (if present); +- f) type of photodetector; +- g) characteristics of the delay detector; +- h) model used to fit the relative group delay data or chromatic dispersion data, and the fitting wavelength range used; +- i) values of coefficients from the fit for each fitting wavelength range; +- j) temperature of the sample and environmental conditions (if necessary). + +#### 6.5.2 Alternative test method: The pulse delay technique + +##### 6.5.2.1 General + +The fibre chromatic dispersion coefficient is derived from the measurement of the relative group delay experienced by the various wavelengths during propagation through a known length of fibre. + +The group delay is measured in the time domain, by detecting, recording and processing the delay experienced by pulses at various wavelengths. + +The chromatic dispersion may be measured at a fixed wavelength or over a wavelength range. + +##### 6.5.2.2 Test apparatus + +A schematic diagram of the test apparatus is shown in Figure 16. + +##### **6.5.2.2.1 Optical source** + +The optical source should be stable in position, intensity and wavelength over a time period sufficiently long to complete the measurement procedure. Laser diodes, (laser diode array (LD-array)), wavelength tunable laser diodes (WTL) (e.g., an external cavity laser (ECL)), broadband sources (e.g., an Nd:YAG laser with a Raman fibre) may be used, depending on the wavelength range of the measurement. + +In any case, the modulating signal should be such as to guarantee a sufficient time resolution in the group delay measurement. + +##### **6.5.2.2.2 Wavelength selection** + +A wavelength selector and monitoring are used to select and monitor the wavelength at which the group delay is to be measured. As a wavelength selector, an optical switch, a monochromator, dispersive devices, optical filters, optical couplers, connectors may be used, depending on the type of light sources and measurement set-up. The selection may be carried out by switching electrical driving signals for different wavelength light sources. + +The wavelength monitoring may be carried out by an optical fibre coupler and a wavelength meter. The wavelength selector and monitor may be used either at the input or at the output end of the fibre under test. + +If a mathematical fit is made to the data, at least one data point should be within 100 nm of the zero-dispersion wavelength $\lambda_0$ . + +##### **6.5.2.2.3 Detector** + +The light emerging from the fibre under test, the reference fibre or the optical divider, etc., is coupled to a photodetector whose signal-to-noise ratio and time resolution are adequate for the measurement. The detector is followed by a low noise amplifier if needed. + +##### **6.5.2.2.4 Reference channel** + +The reference channel may consist of an electrical signal line or optical signal line. A suitable time delay generator may be interposed in this channel. In certain cases, the fibre under test itself can be used as the reference channel line. + +##### **6.5.2.2.5 Delay detector** + +The delay detector should measure the delay time between the reference signal and the channel signal. A high-speed oscilloscope or a sampling oscilloscope could be used. + +##### **6.5.2.2.6 Signal processor** + +A signal processor can be added in order to reduce the noise and/or the jitter in the measured waveform. If needed, a digital computer can be used for the purposes of equipment control, data acquisition and numerical evaluation of the data. + +##### **6.5.2.3 Measurement procedure** + +The fibre under test is suitably coupled to the source and to the detector through the wavelength selector or the optical divider, etc. If needed, a calibration of the chromatic delay of the source may be performed. A suitable compromise between wavelength resolution and signal level should be achieved. Unless the fibre under test is also used as the reference channel line, the temperature of the fibre should be sufficiently stable during the measurement. + +The time delay between the reference signal and the channel signal at the operating wavelength are to be measured by the delay detector. Data processing appropriate to the type of modulation is used in order to obtain the chromatic dispersion coefficient at the operating wavelength. When needed, a + +spectral scan of the group delay versus wavelength can be performed; from the measured values a fitting curve can be completed. + +#### **6.5.2.4 Presentation of the results** + +The following details should be presented: + +- a) test set-up arrangement; +- b) type of modulation used; +- c) source characteristics; +- d) fibre identification and length; +- e) characteristics of the wavelength selector (if present); +- f) type of photodetector; +- g) characteristics of the delay detector; +- h) model used to fit the relative group delay data or chromatic dispersion data, and the fitting wavelength range used; +- i) values of coefficients from the fit for each fitting wavelength range; +- j) temperature of the sample and environmental conditions (if necessary). + +### **6.6 Test methods for macrobend loss** + +#### **6.6.1 Reference test method: Fibre winding** + +##### **6.6.1.1 General** + +The macrobending loss measurement is intended to provide a means whereby certain loss values under different curvature radii are used to evaluate the macrobending performance of single-mode fibres. + +NOTE – A "curvature radius" is defined as the radius of the suitable circular shaped support (e.g., mandrel or guiding groove on a flat surface) on which the fibre can be bent. + +##### **6.6.1.2 Measurement considerations** + +###### **6.6.1.2.1 Sample length** + +The specimen should be a known length of fibre, as specified in the detailed specification. In particular, the length of the sample tested for loss is determined by the measurement set-up, i.e., curvature radius ( $R$ ) and number of turns ( $N$ ); any further fibre length does not affect the measurement results, provided that the signal-to-noise ( $S/N$ ) ratio is optimized. + +##### **6.6.1.2.2 Number of coils** + +The number of coils should be in accordance with the values stated in the relevant [ITU-T G.652], [ITU-T G.653], [ITU-T G.654], [ITU-T G.655], [ITU-T G.656] and [ITU-T G.657]. + +For single-mode fibres, the attenuation increases in a linear fashion with the number of coils. + +For each radius, the number of coils should be chosen in such a way that: + +- a) the induced loss is significantly higher than the detection limit of the set-up; when necessary, e.g., for low-bend loss fibres, tests may be carried out with more coils than the specification requires, followed by linear normalization to the specified number; +- b) the induced loss is significantly lower than the onset of the non-linear region in the set-up; for bending radii in the range 5 to 10 mm this may imply that not more than 5 to 10 coils should be used. + +##### **6.6.1.2.3 Bend radius** + +The value of bend radius should be in accordance with the values stated in the relevant [ITU-T G.652], [ITU-T G.653], [ITU-T G.654], [ITU-T G.655], [ITU-T G.656] and [ITU-T G.657]. It should be considered that the macrobending losses increase exponentially as radius decreases. + +NOTE – Further information on the relationship between macrobending losses and radius can be found in Annex A of [IEC 60793-1-47]. + +##### **6.6.1.2.4 Measurement wavelength** + +The measurement wavelength should be 1550 nm or 1625 nm, in accordance with the relevant [ITU-T G.652], [ITU-T G.653], [ITU-T G.654], [ITU-T G.655], [ITU-T G.656] and [ITU-T G.657]. It should be considered that macrobending losses increase exponentially with the wavelength. + +NOTE 1 – As optical bending losses of single-mode fibres increase with wavelength, a loss specification at the highest envisioned wavelength, i.e., either 1550 or 1625 nm, is suffice. If required, customer and supplier can agree on a lower or higher specification wavelength. + +NOTE 2 – Further information on the relationship between macrobending losses and measurement wavelength can be found in Annex A of [IEC 60793-1-47]. + +NOTE 3 – Further information on approximating bend loss for single-mode fibres across a broad wavelength range at various effective bends can be found in Annex E of [IEC 60793-1-47]. + +#### **6.6.1.3 Test apparatus** + +The apparatus consists of a bending tool and a loss-measurement instrument. + +###### **6.6.1.3.1 Bending tool** + +The bending tool is used to hold the sample bent with a radius as stated in the specification. A mandrel or a guiding groove on a flat surface is applicable. + +Since the actual curvature radius is critical, a maximum tolerance of $\pm 0.1$ mm (for radii lower than or equal to 15 mm) or $\pm 0.5$ to 1.0 mm (for larger radii) is accepted (a tighter tolerance on small radii is required for the higher measurement sensibility). + +The test can be carried out on samples either making complete (360°) turn(s) in open air or around a suitable support (mandrel), or making u-turn(s) (180°) in open air or around suitable supports; the length under test is different in the two configurations, the length of a complete turn being twice the length of a u-turn. In the following, the term "coil" refers to one complete turn: one "coil" is made by two consecutive "u-turns". This should be taken into account when normalizing the results to the length of the sample (number of coils). + +##### **6.6.1.3.2 Loss measurement instrument** + +The loss-measurement instrument uses either the transmitted power monitoring technique (method A of [IEC 60793-1-46]) or the cut-back technique (as in clause 6.4.1), taking care of the appropriate launch condition for the specific fibre type. + +#### **6.6.1.4 Measurement procedure** + +Prepare a flat end face, orthogonal to the fibre axis, at the input and output ends of each test specimen. + +Loosely wind the fibre on the tool, avoiding excessive fibre twist. The number of turns, curvature radius and wavelength at which loss is to be measured are discussed in the following paragraphs. + +Optical powers can be measured in the following two ways: + +- a) the power-monitoring technique, which measures the fibre attenuation increase due to a change from the straight condition to a bent condition; or + +- b) the cut-back technique, which measures the total attenuation of the fibre in the bent condition. In order to determine the induced attenuation due to macrobending, this value should be corrected for the intrinsic attenuation of the fibre. + +The fibre length outside the mandrel and the reference cut-back length should be free of bends that might introduce a significant change in the measurement result. Collection of excess fibre in a bend radius of at least 140 mm is recommended. + +It is also possible to rewind the fibre from a mandrel with a large radius (introducing negligible macrobend loss) to the mandrel with the required radius. In this case, the macrobend loss can be determined directly by using the power-monitoring technique (without the correction for the intrinsic attenuation of the fibre). + +Care should be taken in order not to introduce torsion on any fibre part during the measurements, as this would affect the result. + +NOTE – Whispering gallery mode caused by reflection of radiating mode at cladding-coating or coating-air interface may affect the macrobending loss measurement. For example, multiple fibre coils or coated/stripped fibre coil immersed with adequate refractive index liquid may be used to reduce the interference. + +#### 6.6.1.5 Calculation + +The results are reported in dB as: + +$$Loss(dB) = 10 \log_{10} \left( \frac{P_{str}}{P_{bend}} \right) \quad (6-18)$$ + +where $P_{str}$ is the power measured without the bend and $P_{bend}$ is the power measured with the bend present. + +#### 6.6.1.6 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement; +- b) fibre identification; +- c) length of specimen; +- d) macrobend radius; +- e) number of coils; +- f) wavelength(s) of interest; +- g) macrobending loss (dB) or (dB/turn). + +### 6.7 Test methods for proof testing + +#### 6.7.1 Reference test method: Longitudinal tension + +##### 6.7.1.1 General + +- a) This test method describes procedures for briefly applying tensile loads to an entire continuous length of fibre. The initial length may break into several shorter lengths, and each shorter length is considered to have passed the proof test. An informative background can be found in [b-IEC/TR 62048]. +- b) Proof testing is performed during fibre manufacturing, online as part of the fibre drawing and coating process, or offline as part of the testing process. A break rate (failure per unit length) is statistically expected. + +- c) Standard ambient environmental conditions are used for storage and proof testing: $23 \pm 5$ °C and $50 \pm 20\%$ relative humidity. The storage time prior to proof testing is an item for further study. +- d) Either stress $\sigma$ or strain $\epsilon$ may be used in the measurement. They are related by: + +$$\sigma = E_0(1 + c_s\epsilon)\epsilon \quad (6-19)$$ + +where $E_0$ is Young's modulus at zero stress, and $c_s$ is a parameter (typically between 3 and 6). The determination of parameters $E_0$ and $c_s$ , if needed, is an item for further study. + +- e) The fibre stress is calculated from the applied tension, $T$ , as: + +$$\sigma = \frac{(1-F)T}{\pi a^2} \quad (6-20)$$ + +where $2a$ is the diameter of the glass fibre and $F$ is the fraction of the tension borne by the coating. $F$ is given by: + +$$F = \frac{\sum_{j=1}^n E_j A_j}{E_g \pi a^2 + \sum_{j=1}^n E_j A_j} \quad (6-21)$$ + +$n$ is the number of coating layers + +$E_j$ is the modulus of the $j$ th coating layer + +$A_j$ is the nominal cross-sectional area of the $j$ th coating layer + +$E_g$ is the modulus of the glass fibre + +NOTE 1 – Coating moduli are typically characterized by manufacturers. + +NOTE 2 – In case of strain controlled braked capstan proof test machines, this compensation for the load sharing by the coating is not applicable. + +##### 6.7.1.1.1 Proof test parameters + +- a) The proof stress, $\sigma_p$ , is specified to control the length of the surviving sections of the fibre. The stress applied during the proof test, $\sigma_a$ , is illustrated in Figure 17. The load and unload times, $t_l$ and $t_u$ , and the dwell-time, $t_d$ , are also shown. The tensile load should be applied for as short a time as possible, yet sufficiently long to ensure the glass experiences the proof stress, typically much less than one second. +- b) The applied stress should exceed the specified proof stress at all times. The unload time should be controlled to be less than some maximum values to be agreed between user and manufacturer to control unloading damage. + +![Figure 17: Stress σ versus time t during proof testing. The graph shows a stress profile over time. The y-axis is labeled σ and has two horizontal lines: σ_a (applied proof stress) and σ_p (specified proof stress). The x-axis is labeled t (time). The stress starts at a low value, ramps up linearly to σ_a over a time interval t_l (loading region), then fluctuates around σ_a for a duration t_d (proof test region), and finally ramps down linearly to the initial low value over a time interval t_u (unloading region). The label G.650.1(18)_F17 is in the bottom right corner.](a7f9e5d1862146a136ba5ea891f15f17_img.jpg) + +Figure 17: Stress σ versus time t during proof testing. The graph shows a stress profile over time. The y-axis is labeled σ and has two horizontal lines: σ\_a (applied proof stress) and σ\_p (specified proof stress). The x-axis is labeled t (time). The stress starts at a low value, ramps up linearly to σ\_a over a time interval t\_l (loading region), then fluctuates around σ\_a for a duration t\_d (proof test region), and finally ramps down linearly to the initial low value over a time interval t\_u (unloading region). The label G.650.1(18)\_F17 is in the bottom right corner. + +**Figure 17 – Stress $\sigma$ versus time $t$ during proof testing** + +##### 6.7.1.2 Test apparatus + +###### 6.7.1.2.1 Operating procedure requirements + +- a) In the pay-out and take-up regions, the fibre is maintained with a low value of stress typically not exceeding 10% of the proof stress (see Figure 17). +- b) In the loading region, fibre stress ramps up from a low stress level to the full proof stress. The load time is $t_l$ . +- c) In the proof test region, the applied proof stress, $\sigma_a$ , is maintained at values greater than the specified proof stress, $\sigma_p$ . +- d) In the unloading region, fibre stress ramps down from the applied stress to a low value of stress. The time to unload the fibre is $t_u$ . +- e) The unloading time is controlled to be less than a maximum value to be agreed between user and manufacturer. It can be varied by changing the processing speed or by the gripping capstan design. +- f) The capstans and other support pulleys should be designed and operated to ensure that they do not induce excessive damage. The gripping capstans should be capable of maintaining the applied stress without inducing additional damage from slipping. + +##### 6.7.1.2.2 Proof test machines + +There are several possible machine designs, all of which perform the basic functions required for measuring fibre proof with the indicated general operating requirements. Care should be used in the design so as to prevent coating damage. + +Two machine types are used: + +- braked-capstan machine; +- dead-weight machine. + +Either machine may be used during the fibre-drawing process (online for coated fibre only), or as a separate process step (offline). + +NOTE – There are dynamics with online screening, which are different from offline screening, which should be taken into account. + +- a) *Braked-capstan machine* (Figure 18) + +The fibre is paid out with constant, low tension. Also the rewinding after the proof test is done with constant tension. The levels of the pay-off and take-up tensions are adjustable. + +The proof test load is applied to the fibre between the brake and drive capstans by creating a speed difference between the capstans. Two belts are used to prevent slippage at the capstans. One design can be that the high precision tension gauge measures the load on the fibre and controls the speed difference to achieve the required proof test load. The load level and operating speed of the equipment can be independently set. Another design can be that the difference in speeds between the two capstans is set and controlled directly according to the desired fibre elongation (strain), without tension measurements. + +![Diagram of a braked-capstan proof test machine showing three stages: Stage 1 (Fibre pay-off region), Stage 2 (Proof testing region), and Stage 3 (Fibre take-up region).](9cd85f266cdb1fb3ad544eb3dd3bd5e4_img.jpg) + +The diagram illustrates the typical arrangement of a braked-capstan proof test machine. It is divided into three main regions: + + +- Fibre pay-off region (Stage 1):** Constant tension pay-off. This region includes a 'Dancer' pulley and a 'Brake capstan'. +- Proof testing region (Stage 2):** Proof testing with master and braking capstan and precision load cell. This central region contains a 'Precision tension gauge', a 'Brake capstan', a 'Drive capstan', and the 'Fibre in proof test zone'. +- Fibre take-up region (Stage 3):** Constant tension take-up spooling. This region includes another 'Dancer' pulley and a 'Drive capstan'. + + The fibre path is shown entering from the left, passing through the first dancer, then the brake capstan, then the proof testing zone between the brake and drive capstans, then the drive capstan, then the second dancer, and finally exiting to the right. The diagram is labeled 'G.650.1(18)\_F18' in the bottom right corner. + +Diagram of a braked-capstan proof test machine showing three stages: Stage 1 (Fibre pay-off region), Stage 2 (Proof testing region), and Stage 3 (Fibre take-up region). + +**Figure 18 – Typical arrangement of a braked-capstan proof test machine** + +###### b) *Dead-weight machine* (Figure 19) + +The pay-out dancer and the take-up dancer pulleys are light enough to guide the fibre with minimal tension. The pay-out capstan and the take-up capstan are synchronized with each other. The capstan pinch belts prevent slippage at the capstans, but without additional stress to the fibre or damage to the fibre coatings. A load-arm and a dead-weight on a plate are attached to the shaft of a dead-weight dancer pulley to provide the proof stress to the fibre. An optional idler pulley provides an increased fibre gauge length if needed. + +![Diagram of a dead-weight proof test machine. The diagram shows a central frame with 'Capstan pinch belts' at the top. A vertical 'Load-arm' with a 'Dead-weight (holder)' is suspended from the center. To the left, a 'Pay-out subassembly' contains a 'Pay-out capstan' and a 'Pay-out dancer pulley' near the 'Floor'. To the right, a 'Take-up subassembly' contains a 'Take-up capstan' and a 'Take-up dancer pulley'. An 'Idler pulley' is positioned in the center of the frame. The optical fibre path is shown with dashed lines and arrows indicating the direction of travel from the pay-out subassembly, through the central frame, to the take-up subassembly.](c2c4e63ebb9afc1ab64e39a159890e0f_img.jpg) + +Diagram of a dead-weight proof test machine. The diagram shows a central frame with 'Capstan pinch belts' at the top. A vertical 'Load-arm' with a 'Dead-weight (holder)' is suspended from the center. To the left, a 'Pay-out subassembly' contains a 'Pay-out capstan' and a 'Pay-out dancer pulley' near the 'Floor'. To the right, a 'Take-up subassembly' contains a 'Take-up capstan' and a 'Take-up dancer pulley'. An 'Idler pulley' is positioned in the center of the frame. The optical fibre path is shown with dashed lines and arrows indicating the direction of travel from the pay-out subassembly, through the central frame, to the take-up subassembly. + +G.650.1(18)\_F19 + +**Figure 19 – Dead-weight proof test machine** + +#### 6.7.1.3 Measurement procedure + +##### 6.7.1.3.1 Sample + +- a) The test sample should consist of the entire length of optical fibre, minus short sections at the ends in which all requirements, i.e., maximum unloading time, may not be met. This end allowance length, typically 25 m to 50 m, should be presented. +- b) Fibre failure after proof testing should be evidenced by complete breakage. Examination methods include visual inspection and OTDR measurements. After broken areas are removed, the surviving fibre lengths are considered to have passed the proof test procedure. + +##### 6.7.1.3.2 Calculation + +If the machine is calibrated in tension, the stress is calculated from Equation 6-20. Strain may be obtained from Equation 6-19. + +#### 6.7.1.4 Presentation of the results + +The following details should be presented: + +- a) general description of the apparatus; +- b) fibre identification; +- c) average applied proof stress; +- d) maximum unloading time; +- e) dwell-time; +- f) end allowance length. + +# Annex A + +## Chromatic dispersion fitting + +(This annex forms an integral part of this Recommendation.) + +### A.1 General + +The output from the measurement of chromatic dispersion is either directly measured chromatic dispersion values or group delay values as a function of wavelength. The chromatic dispersion value and dispersion slope is found from the derivatives of this data. The differentiation is most often done after the data has been fitted to a mathematical model. + +This annex gives a general description of chromatic dispersion fitting and outlines a number of standard fitting equations. + +NOTE – Even though dispersion slope characteristics may not be normative requirements, typical values are often provided by manufacturers for ease in dispersion accommodation. + +### A.2 Definition of equations and fitting coefficients + +Table A.1 contains a general description of mathematical models that are fitted. The polynomial formulation is general and can be extended to higher order polynomials via the same principles. + +Table A.2 shows the corresponding equations for dispersion slope. + +Table A.3 shows the formulae for the zero-dispersion wavelength and slope at that wavelength for the 3-term Sellmeier and second-order polynomial models. + +**Table A.1 – Definition of fit types and fit coefficients** + +| Fit type | Equation for group delay | Equation for dispersion data | +|----------------------------------|-------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------| +| 3-term Sellmeier | $A + B \cdot \lambda^2 + C \cdot \lambda^{-2}$ | $2 \cdot B \cdot \lambda - 2 \cdot C \cdot \lambda^{-3}$ | +| 5-term Sellmeier | $A + B \cdot \lambda^2 + C \cdot \lambda^{-2} + D \cdot \lambda^4 + E \cdot \lambda^{-4}$ | $2 \cdot B \cdot \lambda - 2 \cdot C \cdot \lambda^{-3} + 4 \cdot D \cdot \lambda^3 - 4 \cdot E \cdot \lambda^{-5}$ | +| 2nd order polynomial (quadratic) | $A + B \cdot \lambda + C \cdot \lambda^2$ | $B + 2 \cdot C \cdot \lambda$ | +| 3rd order polynomial (cubic) | $A + B \cdot \lambda + C \cdot \lambda^2 + D \cdot \lambda^3$ | $B + 2 \cdot C \cdot \lambda + 3 \cdot D \cdot \lambda^2$ | +| 4th order polynomial | $A + B \cdot \lambda + C \cdot \lambda^2 + D \cdot \lambda^3 + E \cdot \lambda^4$ | $B + 2 \cdot C \cdot \lambda + 3 \cdot D \cdot \lambda^2 + 4 \cdot E \cdot \lambda^3$ | + +**Table A.2 – Slope equations** + +| Fit type | Equation for dispersion slope | +|----------------------------------|---------------------------------------------------------------------------------------------------------| +| 3-term Sellmeier | $2 \cdot B + 6 \cdot C \cdot \lambda^{-4}$ | +| 5-term Sellmeier | $2 \cdot B + 6 \cdot C \cdot \lambda^{-4} + 12 \cdot D \cdot \lambda^2 + 20 \cdot E \cdot \lambda^{-6}$ | +| 2nd order polynomial (quadratic) | $2 \cdot C$ | +| 3rd order polynomial (cubic) | $2 \cdot C + 6 \cdot D \cdot \lambda$ | +| 4th order polynomial | $2 \cdot C + 6 \cdot D \cdot \lambda + 12 \cdot E \cdot \lambda^2$ | + +**Table A.3 – Zero-dispersion wavelength and slope equations** + +| Fit type | Zero-dispersion wavelength | Zero-dispersion slope | +|----------------------------------|----------------------------|-----------------------| +| 3-term Sellmeier | $(C/B)^{1/4}$ | 8B | +| 2nd order polynomial (quadratic) | $-B/(2C)$ | 2C | + +### A.3 Fitting procedure + +For robust numerical fitting, the natural abscissa (wavelengths) should be converted to values with a reduced range by a change of coordinates before completing the least squares regression. After the regression, the fitting parameters should be converted back to the original wavelength scale before completing any of the derivatives. + +A suitable implementation of least squares regression should be chosen to solve the fitting problem. The method should be stable towards noise and other errors introduced during the measurement of the group delay or dispersion data. (See, e.g., [b-Press].) Depending on the source of the input data, equations for group delay or the derivative dispersion is used. + +Care should be taken to include a sufficient number of points in the fitting. When the fitting order and the number of points become comparable, the fitting will not yield accurate results. + +If the fit is made to group delay data, chromatic dispersion data can be calculated from the dispersion equations in Table A.1, using the coefficients found from the fit. Extrapolation to wavelengths outside the fitting region should be used carefully, as the fits might have unphysical behaviour at points outside the region. + +The dispersion slope can be calculated from the equations in Table A.2, using the coefficients found from the fit. + +# Appendix I + +## Methods of cut-off wavelength interpolation + +(This appendix does not form an integral part of this Recommendation.) + +This appendix presents methods of determining the coefficients, $A_t$ and $B_t$ found in clause 6.3.1.3.4, Equation 6-11. Limited negative error method and least square method are described in clauses I.1 and I.2, respectively. Clause I.3 provides an example of the cut-off wavelength interpolation method. + +### I.1 Limited negative error method + +The algorithm is derived from the observation that the transition structures (humps) consist of data points with a positive deviation from the expected ideal curve. The interpolation procedure is based on a theoretical model of the $LP_{11}$ transition region and a method of fitting the data to the model. The procedure has six steps. + +The first two steps define the $LP_{01}$ region, or upper wavelength region. The second two steps define the transition region, where $LP_{11}$ attenuation begins to increase. The fifth step characterizes this region according to a theoretical model. The last step computes the cut-off wavelength, $\lambda_c$ , from the characterization parameters. + +#### Step 1 – Define the upper wavelength region + +##### Lower wavelength of the region + +For multimode reference: + +Find the maximum slope wavelength, the wavelength at which the first difference $a(\lambda) - a(\lambda + 0.01)$ , is largest. For wavelengths greater than the maximum slope wavelength, the lower wavelength of the region is the wavelength at which the attenuation is minimum. + +For bend reference, the following simulates the procedure for multimode reference: + +Find the maximum attenuation wavelength. For wavelengths greater than the maximum attenuation wavelength, the lower wavelength of the region is the wavelength at which the following function is minimum: + +$$a(\lambda) - 8 + 8\lambda \quad (\lambda \text{ in } \mu\text{m})$$ + +##### Upper wavelength of the region + +Lower wavelength of region plus 0.15 $\mu\text{m}$ . + +#### Step 2 – Characterize the attenuation curve, $a(\lambda)$ , of the upper wavelength region as a linear equation in wavelength, $\lambda$ + +$$a(\lambda) \cong A_u + B_u \lambda \quad (\text{I-1})$$ + +The following approaches are suggested: + +Bend reference method: + +Set $B_u = 0$ + +Set $A_u =$ median of attenuation values in the upper wavelength region. + +Multimode reference method: + +Find $A_u$ and $B_u$ so that the sum of the absolute values of error in the upper wavelength region is minimum and so that all errors are non-negative. Find the median of the errors in the upper wavelength region and add to $A_u$ . + +Determine the most negative error of the upper wavelength region, $E$ : + +$$E = \min[a(\lambda) - A_u - B_u\lambda] \quad (I-2)$$ + +#### Step 3 – Find the upper wavelength of the transition region + +Starting at the upper wavelength of the upper wavelength region, from Step 1, determine the maximum wavelength at which the attenuation is 0.1 dB greater than the line found in Step 2. Set the upper wavelength of the transition region to this value plus 10 nm. + +#### Step 4 – Find the lower wavelength of the transition region + +There are various methods to determine this wavelength. The following are examples: + +Let: $\Delta a(\lambda) = a(\lambda) - A_u - B_u(\lambda) \quad (I-3)$ + +- a) Starting with the upper wavelength of the transition region, from Step 3, find the wavelength at which $\Delta a(\lambda)$ has a local maximum and so the difference between this maximum and the next local minimum (at larger $\lambda$ ) is maximum. +- b) The largest wavelength, below the upper wavelength of the transition region, so that: + - $\Delta a(\lambda)$ is greater than 2 dB; and + - b1) there is a local maximum for $\Delta a(\lambda)$ ; or + - b2) there is a local maximum for $\Delta a(\lambda) - \Delta a(\lambda + 0.01)$ . + +#### Step 5 – Characterize the transition zone with the model and constraints on errors + +The model is a linear regression of a transformation. Constraints on errors control negative regression errors so that the inverse transform of the fitted line will not produce negative attenuation errors less than $E$ , from Step 2. Fitting the data with constraints on errors may be done with simplex linear programming methods. + +Find $A_t$ and $B_t$ , from clause 6.3.1.3.4, Equation 6-11, so that the sum of the absolute values of error is minimized and so that no error is less than $-v(\lambda)$ , with $v(\lambda)$ given as a function of $E$ , from Step 2: + +$$w(\lambda) = 10^{\frac{\Delta a(\lambda) - E}{10}} \quad (I-4)$$ + +$$z(\lambda) = 10 \log \left[ -\frac{10}{A} \log \left( \frac{w(\lambda) - 1}{\rho} \right) \right] \quad (I-5)$$ + +$$v(\lambda) = Y(\lambda) - z(\lambda) \quad (I-6)$$ + +#### Step 6 – Evaluate the slope of the transition and compute the cut-off wavelength, $\lambda_c$ + +If $B_t$ is greater than some small negative values, e.g., $-1$ to $-0.1$ , reduce the upper wavelength of the transition region by 10 nm and repeat Step 5. + +Otherwise, compute $\lambda_c$ : + +$$\lambda_c = -\frac{A_t}{B_t} \quad (I-7)$$ + +### I.2 Least squares method + +This algorithm is based on the assumption that the structure sometimes seen in the transition region is caused by an interference effect around the position of the ideal curve. + +The mathematical model is the same as that used in the limited negative error method. + +**Step 1** – As limited negative error method. + +**Step 2** – As limited negative error method. E in Equation (I-2) is not required. + +**Step 3** – As limited negative error method. + +**Step 4** – As limited negative error method. + +**Step 5** – Characterize the transition zone. + +The model is a least squares best fit of a transformation. + +Find $A_t$ and $B_t$ from clause 6.3.1.3.4, Equation 6-11, so that the sum of the squares of the errors is minimized, using equations 6-8, 6-9, 6-10 and: + +$$W(\lambda) = 10^{\Delta a(\lambda)/10} \quad (\text{I-8})$$ + +**Step 6** – As limited negative error method. + +### I.3 Example + +Figure I.1 shows an example of the cut-off plot for several fibre samples. In the absence of spurious humps or excessive noise in the upper-wavelength region, accurate values for cut-off wavelength can be determined without an interpolation method (Sample 1, 2, 5 in Figure I.1). On the contrary, the interpolation method will be helpful to determine the cut-off wavelength and improve the precision (Sample 3, 4 in Figure I.1). + +![Figure I.1: Cut-off wavelength interpolation for some fibre samples. The graph plots Relative attenuation (dB) on the y-axis (from -18.00 to -11.00) against Wavelength (nm) on the x-axis (from 1000 to 1400). Five fibre samples are shown: Sample 1 (ITU-T G.652.D, λc = 1261.3 nm), Sample 2 (ITU-T G.657.A2, λc = 1287.5 nm), Sample 3 (ITU-T G.657.A2, λc = 1342.9 nm w/interpolation), Sample 4 (ITU-T G.657.B3, λc = 1337.2 nm w/interpolation), and Sample 5 (ITU-T G.657.A1, λc = 1329.9 nm). The curves show a transition from lower attenuation to higher attenuation as wavelength increases. Samples 3 and 4 show a 'hump' or 'noise' in the transition region, necessitating interpolation for accurate cut-off wavelength determination.](d5967e76981878bedf85aef53018e042_img.jpg) + +Figure I.1 is a line graph showing Relative attenuation (dB) on the y-axis (ranging from -18.00 to -11.00) versus Wavelength (nm) on the x-axis (ranging from 1000 to 1400). The graph displays five fibre samples, each showing a characteristic cut-off curve. The samples are labeled as follows: + +- Sample 5: ITU-T G.657.A1, $\lambda_c = 1329.9$ nm +- Sample 3: ITU-T G.657.A2, $\lambda_c = 1342.9$ nm w/interpolation +- Sample 1: ITU-T G.652.D, $\lambda_c = 1261.3$ nm +- Sample 2: ITU-T G.657.A2, $\lambda_c = 1287.5$ nm +- Sample 4: ITU-T G.657.B3, $\lambda_c = 1337.2$ nm w/interpolation + +The curves show a transition from lower attenuation to higher attenuation as wavelength increases. Samples 3 and 4 show a 'hump' or 'noise' in the transition region, necessitating interpolation for accurate cut-off wavelength determination. + +Figure I.1: Cut-off wavelength interpolation for some fibre samples. The graph plots Relative attenuation (dB) on the y-axis (from -18.00 to -11.00) against Wavelength (nm) on the x-axis (from 1000 to 1400). Five fibre samples are shown: Sample 1 (ITU-T G.652.D, λc = 1261.3 nm), Sample 2 (ITU-T G.657.A2, λc = 1287.5 nm), Sample 3 (ITU-T G.657.A2, λc = 1342.9 nm w/interpolation), Sample 4 (ITU-T G.657.B3, λc = 1337.2 nm w/interpolation), and Sample 5 (ITU-T G.657.A1, λc = 1329.9 nm). The curves show a transition from lower attenuation to higher attenuation as wavelength increases. Samples 3 and 4 show a 'hump' or 'noise' in the transition region, necessitating interpolation for accurate cut-off wavelength determination. + +G.650.1(18)\_FI.1 + +**Figure I.1 – Cut-off wavelength interpolation for some fibre samples** + +# Appendix II + +## Test method for measuring longitudinal uniformity of chromatic dispersion based on the backscattering technique + +(This appendix does not form an integral of this Recommendation.) + +### II.1 General + +A test method is described by which to determine the longitudinal uniformity of the chromatic dispersion of a single-mode optical fibre based on bidirectional backscattering measurements. This technique can evaluate the uniformity of the waveguide and material dispersion individually. Moreover, this technique can be used to measure the mode field diameter. Procedures for the calibration of backscattering equipment are provided in [IEC 61746-1]. + +### II.2 Test apparatus + +#### II.2.1 General considerations (as in clause 6.4.2.2.1) + +An example of the apparatus is shown in Figure II.1. + +![Schematic of apparatus for chromatic dispersion uniformity measurement](2438c4dd81a8b76ec881d47d87b11fc3_img.jpg) + +The diagram illustrates the test apparatus for chromatic dispersion uniformity measurement. It begins with an **Optical source** on the left, which emits light into an **Optical coupling system**. This system connects to a **Branching device**. From the branching device, one path leads to another **Optical coupling system**, which is connected to a **Reference fibre**. This reference fibre is joined to the **Fibre under test**, which is also connected to another **Reference fibre**. The backscattered signal from the fibre under test is captured by an **Optical detector**. The signal then passes through an **Amplifier** and into a **Signal processor**. The signal processor is connected to an **Oscilloscope** and a **Data acquisition system**. The data acquisition system is further connected to a **Computer**. A feedback loop from the computer returns to the optical source. + +Schematic of apparatus for chromatic dispersion uniformity measurement + +**Figure II.1 – Schematic of apparatus for chromatic dispersion uniformity measurement** + +#### II.2.2 Optical source (as in clause 6.4.2.2.2) + +#### II.2.3 Optical coupling system (as in clause 6.4.2.2.3) + +#### II.2.4 Branching device (as in clause 6.4.2.2.4) + +#### II.2.5 Optical detector (as in clause 6.4.2.2.5) + +#### II.2.6 Amplifier (as in clause 6.4.2.2.6) + +#### II.2.7 Signal processor (as in clause 6.4.2.2.7) + +#### II.2.8 Cladding mode stripper (as in clause 6.4.2.2.8) + +#### II.2.9 Reference fibre + +The refractive index profile of the reference fibre should be similar to that of the test fibre and its length is restricted to maintain a good longitudinal uniformity, but it should be longer than the input dead-zone of the backscattering measurements. In addition, the mode field diameter of the reference fibre should be measured as a function of wavelength. This reference fibre can be used to estimate the absolute value of the mode field diameter and relative index difference from the backscattering measurements. + +### II.3 Measurement procedure + +- Connect reference fibres to both ends of the test fibre. +- Align the fibre under test with the optical coupling system. +- As b) in clause 6.4.2.3. +- As c) in clause 6.4.2.3. +- Obtain the bidirectional backscattering imperfection loss curve using the two measured and recorded unidirectional backscattering loss curves, according to the procedure outlined in the following: + +Let $S_1(x)$ and $S_2(z)$ be functions describing the two unidirectional backscattering loss curves expressed in dB, with $x$ and $z$ being the distances from the fibre ends nearest the respective launch sites and $L = x + z$ . The bidirectional backscattering imperfection loss curve is given by: + +$$I(x, z) = \frac{S_1(x, \lambda) + S_2(L - x, \lambda)}{2} \quad (\text{II-1})$$ + +- Obtain the imperfection loss normalized by that at position $x_0$ in the reference fibre according to the procedure outlined in the following: + +$$\begin{aligned} I_n(x, \lambda) &= I(x, \lambda) - I(x_0, \lambda) \\ &= 20 \log \left\{ \frac{W(x_0, \lambda)}{W(x, \lambda)} \right\} + 10 \log \left[ \left\{ \frac{1 + 0.62\Delta(x)}{1 + 0.62\Delta(x_0)} \right\} \left\{ \frac{50 - \Delta(x)}{50 - \Delta(x_0)} \right\} \right] \\ &= 20 \log \left\{ \frac{W(x_0, \lambda)}{W(x, \lambda)} \right\} + k \end{aligned} \quad (\text{II-2})$$ + +where coefficient $k$ is defined as: + +$$k = 10 \log \left[ \left\{ \frac{1 + 0.62\Delta(x)}{1 + 0.62\Delta(x_0)} \right\} \left\{ \frac{50 - \Delta(x)}{50 - \Delta(x_0)} \right\} \right] \quad (\text{II-3})$$ + +- Obtain the mode field diameter distribution $2W(x, \lambda)$ according to the procedure outlined in the following: + +Let the mode field diameter at position $x_0$ in the reference fibre be $2W(x_0, \lambda)$ . The mode field diameter distribution is given by: + +$$2W(x, \lambda) = 2W(x_0, \lambda) \cdot 10^{\frac{-I_n(x, \lambda) + k}{20}} \quad (\text{II-4})$$ + +If the reference and test fibres have the same index profile and relative index difference, let coefficient $k = 0$ . + +If the relative index difference in the test fibre is not the same as that in the reference fibre, determine coefficient $k$ by using Equation II-3 and the mode field diameter value at $x$ in the test fibre which is evaluated in advance. + +If the adjustment factors $f$ and $g$ , which are determined as described in c) in clause 6.1.4.3.2, are given, the mode field diameter distribution is given by: + +$$2W(x, \lambda) = 2W(x_0, \lambda) \cdot 10^{\frac{-g \cdot I_n(x, \lambda) + f}{20}} \quad (\text{II-5})$$ + +If the relative index difference in the test fibre is unknown, the mode field diameter value at $x$ in the test fibre is obtained with Equation II-6 considering the second position $x_1$ in the reference fibre. + +$$2W(x, \lambda) = 2W(x_0, \lambda) \cdot \left[ \frac{2W(x_1, \lambda)}{2W(x_0, \lambda)} \right]^{\frac{I(x, \lambda) - I(x_0, \lambda)}{I(x_1, \lambda) - I(x_0, \lambda)}} \quad (\text{II-6})$$ + +h) Repeat the above procedures for two or more different wavelengths. + +i) Obtain the coefficients $g_0$ , $g_1$ , and $g_2$ which satisfy Equation II-7 using the above mode field radii $W(x, \lambda)$ : + +$$W(x, \lambda) = g_0(x) + g_1(x)\lambda^{1.5} + g_2(x)\lambda^6 \quad (\text{three or more wavelengths}) \quad (\text{II-7})$$ + +or: + +$$W(x, \lambda) = g_0(x) + g_1(x)\lambda^{1.5} \quad (\text{two or more wavelengths}) \quad (\text{II-8})$$ + +This expression may be evaluated by a least squares fit of the data $W(x, \lambda_i)$ ( $i = 1, \dots, n$ ). + +j) Obtain the waveguide dispersion distribution $D_w(x, \lambda)$ in ps/(nm $\times$ km) outlined in the following: + +$$D_w(x, \lambda) = \frac{\lambda}{2\pi^2 c n W(x, \lambda)^2} \left\{ 1 - \frac{2\lambda}{W(x, \lambda)} \left( \frac{3}{2} g_1(x) \lambda^{0.5} + 6 g_2(x) \lambda^5 \right) \right\} \quad (\text{three or more wavelengths}) \quad (\text{II-9})$$ + +or: + +$$D_w(x, \lambda) = \frac{\lambda}{2\pi^2 c n W(x, \lambda)^2} \left\{ 1 - \frac{3 g_1(x) \lambda^{1.5}}{W(x, \lambda)} \right\} \quad (\text{two or more wavelengths}) \quad (\text{II-10})$$ + +where $c$ and $n$ show the light velocity in m/s and the maximum refractive index of the core, respectively. + +k) Obtain the relative index difference distribution $\Delta(x)$ in % according to the procedure outlined in the following: + +If the reference and test fibres have the same index profile, obtain the coefficients $c_0$ , $c_1$ and $c_2$ at the reference fibre which satisfy the following equation using mode field diameter $2W(x_0, \lambda)$ , core diameter $2a(x_0)$ and cut-off wavelength $\lambda_c(x_0)$ : + +$$\frac{W(x_0, \lambda)}{a(x_0)} = c_0 + c_1 \left\{ \frac{\lambda}{\lambda_c(x_0)} \right\}^{1.5} + c_2 \left\{ \frac{\lambda}{\lambda_c(x_0)} \right\}^6 \quad (\text{II-11})$$ + +Calculate the characteristic of the ratio $R_W$ of mode field diameters of two wavelengths ( $\lambda_1$ and $\lambda_2$ ) as a function of the cut-off wavelength $\lambda_c$ using the above coefficients $c_0$ , $c_1$ and $c_2$ . + +$$R_W \equiv \frac{2W(\lambda_1)}{2W(\lambda_2)} = \frac{c_0 + c_1 \left( \frac{\lambda_1}{\lambda_c} \right)^{1.5} + c_2 \left( \frac{\lambda_1}{\lambda_c} \right)^6}{c_0 + c_1 \left( \frac{\lambda_2}{\lambda_c} \right)^{1.5} + c_2 \left( \frac{\lambda_2}{\lambda_c} \right)^6} \quad (\text{II-12})$$ + +Determine the approximate function between the ratio $R_W$ of mode field diameters at two wavelengths and cut-off wavelength $\lambda_c$ . + +Obtain the cut-off wavelength distribution $\lambda_c(x)$ by applying the above approximate function to the ratio of the measured mode field diameter distributions. + +Obtain the core diameter distribution $2a(x)$ substituting the mode field diameter distribution $2W(x)$ and the cut-off wavelength distribution $\lambda_c(x)$ into Equation II-11. + +Obtain the relative index difference distribution $\Delta(x)$ in % using Equation II-13: + +$$\Delta(x) = \left\{ \frac{a(x_0)}{a(x)} \right\}^2 \left\{ \frac{\lambda_c(x)}{\lambda_c(x_0)} \right\}^2 \Delta(x_0) \quad (\text{II-13})$$ + +Alternatively, relative index difference $\Delta(x)$ in % is obtained with Equation II-14 using the relative index difference at position $x_0$ in the reference fibre $\Delta(x_0)$ . + +$$\Delta(x) = \frac{1}{0.62} \left[ \{1 + 0.62\Delta(x_0)\} \cdot 10^{\frac{I_n(x,\lambda) - 20\log\left\{ \frac{2W(x_0,\lambda)}{2W(x,\lambda)} \right\}}{10}} - 1 \right] \quad (\text{II-14})$$ + +- 1) Obtain the material dispersion distribution $D_m(x, \lambda)$ in ps/(nm × km) using the above relative index difference distribution $\Delta(x)$ . + +Here, the approximate equation of the material dispersion can be obtained as a function of wavelength and relative index difference. + +The material dispersion $D_m(\lambda)$ can be estimated by using equations II-15 and II-16: + +$$D_m(\lambda) = -\frac{\lambda}{c} \frac{d^2 n(\lambda)}{d\lambda^2} \quad (\text{II-15})$$ + +$$n^2(\lambda) - 1 = \sum_{i=1}^k \frac{B_i \lambda^2}{\lambda^2 - A_i^2} \quad (\text{II-16})$$ + +where $A_i$ and $B_i$ show the Sellmeier coefficients and both coefficients $A_i$ and $B_i$ as a function of dopant content corresponding to the relative-index difference $\Delta$ were given in [b-Kobayashi] and [b-Fleming]. + +Calculate an estimated function $D_m(\lambda)$ of material dispersion against the relative-index difference $\Delta$ by using equations II-15 and II-16. + +The material dispersion against the relative-index difference $\Delta$ is obtained as follows: + +$$D_m(\lambda) = m_1(\lambda) + h \cdot \Delta \cdot m_2(\lambda) \quad (\text{II-17})$$ + +where $h$ shows the constant. + +Obtain the chromatic dispersion distribution $D(x, \lambda)$ in ps/(nm × km) outlined in the following: + +$$D(x, \lambda) = D_m(x, \lambda) + D_w(x, \lambda) \quad (\text{II-18})$$ + +### **II.4 Presentation of the results** + +The following details should be presented: + +- a) test set-up arrangement; +- b) kind of signal processing used; +- c) pulse width; +- d) test wavelengths; +- e) mode field diameter distribution in $\mu\text{m}$ ; +- f) chromatic dispersion distribution in $\text{ps}/(\text{nm} \times \text{km})$ . + +# Appendix III + +## Example of a matrix model + +(This appendix does not form an integral part of this Recommendation.) + +### III.1 Example characterizing matrices for ITU-T G.652.D and ITU-T G.654.E fibre + +Tables III.1 and III.2 provide example characterizing matrices for ITU-T G.652.D and ITU-T G.654.E fibres, respectively. Please note they are given for illustrative purposes only. Two characterizing matrices were derived from multiple products they were provided by different manufacturers and operators (including cabled and uncabled fibres). They cannot be directly used for spectral attenuation modelling of individual product as described in clause 6.4.4.3. The example matrix for ITU-T G.652.D fibre consists of an $m \times n = 74 \times 4$ matrix to model the spectral attenuation over the range of 1260 nm to 1625 nm (in steps of 5 nm) using 1310 nm, 1380 nm, 1550 nm and 1625 nm as predictor wavelengths. Example matrix for ITU-T G.654.E fibre consists of $m \times n = 20 \times 3$ matrix to model the spectral attenuation over the range of 1530 nm to 1625 nm (in steps of 5 nm) using 1530 nm, 1550 nm and 1625 nm as predictor wavelengths. + +NOTE – Appendix III in the 2018 edition of Recommendation [ITU-T G.650.1] contains an example characterizing matrix $M$ for ITU-T G.652 fibre with technical reference for spectral attenuation modelling [b-Hanson]. + +**Table III.1 – Example characterizing matrix $M$ for ITU-T G.652.D fibre +(for illustrative purpose only)** + +| Output wavelength
( $\mu\text{m}$ ) | Predictive wavelengths | | | | +|----------------------------------------|------------------------|---------|---------|---------| +| | 1310 nm | 1380 nm | 1550 nm | 1625 nm | +| 1.260 | 0.6960 | 0.0823 | 1.1801 | -0.4553 | +| 1.265 | 0.6601 | 0.0873 | 1.2351 | -0.4841 | +| 1.270 | 0.6815 | 0.0849 | 1.1405 | -0.4564 | +| 1.275 | 0.7494 | 0.0725 | 0.9681 | -0.4174 | +| 1.280 | 0.8298 | 0.0499 | 0.7616 | -0.3510 | +| 1.285 | 0.8963 | 0.0323 | 0.5790 | -0.2921 | +| 1.290 | 0.9790 | 0.0264 | 0.3474 | -0.2278 | +| 1.295 | 1.0316 | 0.0181 | 0.1906 | -0.1804 | +| 1.300 | 1.0376 | 0.0089 | 0.0597 | -0.0803 | +| 1.305 | 1.0435 | 0.0067 | 0.0078 | -0.0622 | +| 1.310 | 1.0000 | 0.0000 | 0.0000 | 0.0000 | +| 1.315 | 0.9992 | 0.0151 | -0.0225 | -0.0203 | +| 1.320 | 0.9710 | 0.0272 | -0.0186 | -0.0176 | +| 1.325 | 0.9340 | 0.0311 | -0.0049 | 0.0026 | +| 1.330 | 0.9073 | 0.0399 | -0.0040 | 0.0111 | +| 1.335 | 0.8947 | 0.0446 | -0.0316 | 0.0300 | +| 1.340 | 0.8888 | 0.0496 | -0.0587 | 0.0369 | +| 1.345 | 0.8956 | 0.0492 | -0.1067 | 0.0516 | +| 1.350 | 0.8975 | 0.0559 | -0.1732 | 0.0810 | +| 1.355 | 0.8901 | 0.0662 | -0.2167 | 0.1002 | + +**Table III.1 – Example characterizing matrix M for ITU-T G.652.D fibre +(for illustrative purpose only)** + +| Output wavelength
( $\mu\text{m}$ ) | Predictive wavelengths | | | | +|----------------------------------------|------------------------|---------|---------|---------| +| | 1310 nm | 1380 nm | 1550 nm | 1625 nm | +| 1.360 | 0.8498 | 0.0936 | -0.2092 | 0.1021 | +| 1.365 | 0.7607 | 0.1536 | -0.2255 | 0.1636 | +| 1.370 | 0.5826 | 0.3307 | -0.2123 | 0.1807 | +| 1.375 | 0.4058 | 0.6565 | -0.4301 | 0.2178 | +| 1.380 | 0.0000 | 1.0000 | 0.0000 | 0.0000 | +| 1.385 | 0.1657 | 0.9779 | -0.3568 | 0.0821 | +| 1.390 | 0.2357 | 0.8394 | -0.2813 | 0.0664 | +| 1.395 | 0.2346 | 0.6712 | -0.0876 | 0.0949 | +| 1.400 | 0.2375 | 0.5442 | 0.0184 | 0.1433 | +| 1.405 | 0.2629 | 0.4332 | 0.1022 | 0.1570 | +| 1.410 | 0.3040 | 0.3485 | 0.1133 | 0.1787 | +| 1.415 | 0.3361 | 0.2725 | 0.1339 | 0.1956 | +| 1.420 | 0.3652 | 0.2130 | 0.1338 | 0.2148 | +| 1.425 | 0.3961 | 0.1704 | 0.1380 | 0.2033 | +| 1.430 | 0.4235 | 0.1398 | 0.1356 | 0.1876 | +| 1.435 | 0.4261 | 0.1267 | 0.1357 | 0.1851 | +| 1.440 | 0.4377 | 0.1072 | 0.1375 | 0.1767 | +| 1.445 | 0.4539 | 0.0735 | 0.1527 | 0.1700 | +| 1.450 | 0.4638 | 0.0604 | 0.1518 | 0.1595 | +| 1.455 | 0.4564 | 0.0464 | 0.1867 | 0.1450 | +| 1.460 | 0.4439 | 0.0381 | 0.2081 | 0.1434 | +| 1.465 | 0.4260 | 0.0290 | 0.2524 | 0.1306 | +| 1.470 | 0.4102 | 0.0234 | 0.2807 | 0.1249 | +| 1.475 | 0.3919 | 0.0174 | 0.3238 | 0.1108 | +| 1.480 | 0.3632 | 0.0186 | 0.3814 | 0.0894 | +| 1.485 | 0.3405 | 0.0133 | 0.4164 | 0.0896 | +| 1.490 | 0.3073 | 0.0115 | 0.4868 | 0.0684 | +| 1.495 | 0.2852 | 0.0045 | 0.5629 | 0.0325 | +| 1.500 | 0.2616 | -0.0008 | 0.6257 | 0.0093 | +| 1.505 | 0.2371 | -0.0016 | 0.6729 | -0.0040 | +| 1.510 | 0.2070 | -0.0024 | 0.7227 | -0.0106 | +| 1.515 | 0.1718 | 0.0032 | 0.7609 | -0.0073 | +| 1.520 | 0.1361 | 0.0078 | 0.8172 | -0.0181 | +| 1.525 | 0.1140 | 0.0044 | 0.8320 | 0.0004 | +| 1.530 | 0.0913 | 0.0087 | 0.8628 | -0.0059 | +| 1.535 | 0.0711 | 0.0120 | 0.8793 | -0.0007 | + +**Table III.1 – Example characterizing matrix M for ITU-T G.652.D fibre +(for illustrative purpose only)** + +| Output wavelength
( $\mu\text{m}$ ) | Predictive wavelengths | | | | +|----------------------------------------|------------------------|---------|---------|---------| +| | 1310 nm | 1380 nm | 1550 nm | 1625 nm | +| 1.540 | 0.0537 | 0.0072 | 0.9427 | –0.0317 | +| 1.545 | 0.0325 | 0.0047 | 0.9495 | –0.0061 | +| 1.550 | 0.0000 | 0.0000 | 1.0000 | 0.0000 | +| 1.555 | 0.0057 | 0.0011 | 0.9308 | 0.0506 | +| 1.560 | 0.0063 | –0.0020 | 0.8803 | 0.0983 | +| 1.565 | 0.0073 | –0.0020 | 0.8099 | 0.1607 | +| 1.570 | 0.0036 | –0.0076 | 0.7811 | 0.2001 | +| 1.575 | –0.0042 | –0.0148 | 0.7276 | 0.2730 | +| 1.580 | –0.0013 | –0.0102 | 0.6393 | 0.3451 | +| 1.585 | –0.0113 | –0.0118 | 0.6090 | 0.3935 | +| 1.590 | –0.0099 | –0.0182 | 0.5410 | 0.4675 | +| 1.595 | –0.0128 | –0.0257 | 0.5053 | 0.5210 | +| 1.600 | –0.0117 | –0.0201 | 0.4481 | 0.5706 | +| 1.605 | –0.0137 | –0.0231 | 0.4044 | 0.6269 | +| 1.610 | –0.0056 | –0.0195 | 0.2859 | 0.7294 | +| 1.615 | 0.0002 | –0.0113 | 0.1872 | 0.8124 | +| 1.620 | –0.0054 | –0.0049 | 0.1404 | 0.8686 | +| 1.625 | 0.0000 | 0.0000 | 0.0000 | 1.0000 | + +**Table III.2 – Example characterizing matrix M for ITU-T G.654.E fibre +(for illustrative purpose only)** + +| Output wavelength
( $\mu\text{m}$ ) | Predictive wavelengths | | | +|----------------------------------------|------------------------|---------|---------| +| | 1530 nm | 1550 nm | 1625 nm | +| 1.530 | 1.0000 | 0.0000 | 0.0000 | +| 1.535 | 0.6707 | 0.3387 | –0.0078 | +| 1.540 | 0.3970 | 0.6170 | –0.0119 | +| 1.545 | 0.1898 | 0.8217 | –0.0103 | +| 1.550 | 0.0000 | 1.0000 | 0.0000 | +| 1.555 | –0.1212 | 1.1046 | 0.0144 | +| 1.560 | –0.2274 | 1.1837 | 0.0389 | +| 1.565 | –0.3031 | 1.2222 | 0.0730 | +| 1.570 | –0.3727 | 1.2526 | 0.1101 | +| 1.575 | –0.4223 | 1.2519 | 0.1577 | +| 1.580 | –0.4474 | 1.2197 | 0.2128 | + +**Table III.2 – Example characterizing matrix M for ITU-T G.654.E fibre +(for illustrative purpose only)** + +| Output wavelength
( $\mu\text{m}$ ) | Predictive wavelengths | | | +|----------------------------------------|------------------------|---------|---------| +| | 1530 nm | 1550 nm | 1625 nm | +| 1.585 | –0.4394 | 1.1501 | 0.2724 | +| 1.590 | –0.3896 | 1.0346 | 0.3363 | +| 1.595 | –0.3643 | 0.9329 | 0.4122 | +| 1.600 | –0.3391 | 0.8255 | 0.4948 | +| 1.605 | –0.2768 | 0.6782 | 0.5810 | +| 1.610 | –0.1897 | 0.5015 | 0.6726 | +| 1.615 | –0.1207 | 0.3338 | 0.7747 | +| 1.620 | –0.0667 | 0.1766 | 0.8834 | +| 1.625 | 0.0000 | 0.0000 | 1.0000 | + +### III.2 Illustrative relationship with predictor wavelengths + +Figures III.1 and III.2 illustrate the wavelength dependence of the modelling errors as a function of the number of predictor wavelengths. Figure III.1 corresponds to ITU-T G.652.D, and Figure III.2 corresponds to ITU-T G.654.E fibres, respectively. In Figure III.1, solid, dashed and dotted lines show the results obtained when predictor wavelengths were set at (1310, 1380, 1550, 1625 nm), (1310, 1380, 1550 nm), and (1310, 1550, 1625 nm), respectively. Solid and dashed lines in Fig. III.2 show the results obtained when the predictor wavelengths were set at (1530, 1550, 1625 nm) and (1550, 1625 nm), respectively. These examples facilitate understanding of the relationship between modelling errors and choices of the predictor wavelengths. The absolute values of the modelling errors do not have much meaning because multiple samples (including cabled ones) provided from different manufactures and operators were used. These examples show that: + +- Selecting the shortest and longest predictor wavelengths adequately to cover the desired modelling range, +- Choosing distinctive wavelengths in terms of spectral attenuation dependency as predictor wavelengths help reduce undesired modelling errors. + +![Figure III.1: Illustrative wavelength dependence of the modelling error for ITU-T G.652.D fibres. The graph plots Modelling error (dB/km) on the y-axis (from -0.05 to 0.05) against Wavelength (μm) on the x-axis (from 1.26 to 1.61). Three lines are shown: solid, dashed, and dotted. The dotted line shows a significant peak around 1.38 μm. The solid and dashed lines remain relatively flat, mostly within ±0.01 dB/km. The label G.650.1(20)_FIII.1 is in the bottom right.](37e4831a48bd47b99dcf6837787652ae_img.jpg) + +Figure III.1: Illustrative wavelength dependence of the modelling error for ITU-T G.652.D fibres. The graph plots Modelling error (dB/km) on the y-axis (from -0.05 to 0.05) against Wavelength (μm) on the x-axis (from 1.26 to 1.61). Three lines are shown: solid, dashed, and dotted. The dotted line shows a significant peak around 1.38 μm. The solid and dashed lines remain relatively flat, mostly within ±0.01 dB/km. The label G.650.1(20)\_FIII.1 is in the bottom right. + +**Figure III.1 – Illustrative wavelength dependence of the modelling error for ITU-T G.652.D fibres. Solid, dashed and dotted lines show the results obtained when the predictor wavelengths were set at (1310, 1380, 1550, 1625 nm), (1310, 1380, 1550 nm), and (1310, 1550, 1625 nm), respectively** + +![Figure III.2: Wavelength dependence of estimation error for ITU-T G.654.E fibre. The graph plots Estimation error (dB/km) on the y-axis (from -0.050 to 0.050) against Wavelength (mm) on the x-axis (from 1.52 to 1.64). Two lines are shown: solid (three-reference model) and dashed (two-reference model). Both lines are very close to zero, with the dashed line showing slightly more variation. The label G.650.1(20)_FIII.2 is in the bottom right.](c772a48faa2cb17e1bf2a86ad057b4c9_img.jpg) + +Figure III.2: Wavelength dependence of estimation error for ITU-T G.654.E fibre. The graph plots Estimation error (dB/km) on the y-axis (from -0.050 to 0.050) against Wavelength (mm) on the x-axis (from 1.52 to 1.64). Two lines are shown: solid (three-reference model) and dashed (two-reference model). Both lines are very close to zero, with the dashed line showing slightly more variation. The label G.650.1(20)\_FIII.2 is in the bottom right. + +**Figure III.2 – Wavelength dependence of estimation error for ITU-T G.654.E fibre. Solid and dashed lines correspond to three- and two-reference model, respectively** + +# Appendix IV + +## Test methods for measuring coherent MPI in short optical fibre cables (jumpers) + +(This appendix does not form an integral part of this Recommendation.) + +The measurement of coherent multipath interference (MPI) is performed to ensure low noise contribution from a short (typically $< 10$ m) cabled optical fibre. This test is particularly relevant to ITU-T G.657 fibres, as they present a wide variety of high-order mode (HOM) transmission characteristics and tend to tightly bind these modes to the fibre core (mode stripping is difficult). MPI values are measured as a function of wavelength, with particular attention to the shortest wavelengths to be used over the cable. The result will be a function of both the length of the cable sample and the splice (connector) loss at the cable ends. Hence these parameters should be quantified and shared by the manufacturer. A further variable is the cable geometrical layout. A straight cable layout will generally give the highest MPI though "resonance wavelengths" may appear where the HOM is strongly damped, and the MPI is very low. More realistic geometries are preferred and are obtained by using controlled bending of the cable. + +There are three methods for measuring MPI. The first, the "Narrowband ECL/PM method", uses an external cavity laser (ECL) and a power meter (PM) and is quite accurate but may be time consuming and limited in wavelength range. The second, the "Wideband LED/OSA method", uses a wideband source (such as an edge emitting light emitting diode, EELED) and an optical spectrum analyser (OSA). This method typically has a higher noise floor but enables MPI measurements over the entire transmission band of the fibre. The third method uses a fixed wavelength light source, such as in an actual transmitter, and involves varying the length of the jumper by stretching. It is termed the "Fibre stretching" or "FS" method. This method has the advantages of: + +- 1) low cost light sources; +- 2) ability to find MPI using actual transceivers in a system test arrangement; and +- 3) avoidance of extraneous wavelength dependencies in the test set-up. + +Disadvantages include a more complicated set-up and the inability to measure fibres in configurations other than straight, under tension. + +### IV.1 First test method: The narrowband ECL/PM technique + +#### IV.1.1 General + +The narrowband ECL/PM technique monitors transmitted optical power through the jumper as a function of wavelength. The interference phenomenon between the fundamental, $LP_{01}$ , and HOM is measured by capturing the maximum and minimum transmitted power over a range of wavelengths. Polarization variation of the input is used to ensure true power extremes are found. + +#### IV.1.2 Test apparatus + +A schematic of the apparatus required for the first test method is shown in Figure IV.1. + +##### IV.1.2.1 Optical source + +A tuneable external cavity laser (ECL) is used with recommended characteristics: line width $< 200$ kHz, power $> -4$ dBm at the shortest wavelengths of interest (usually 1260 nm) and wide tuning range ( $\sim 100$ nm). The stability of the power should be $< 0.01$ dB over the testing time and should vary $< 0.05$ dB over the wavelength range required to sample the free spectral range (FSR) of the jumper interference pattern (this is typically $\sim 2$ nm). The laser RIN should be less than $-145$ dBm/Hz over the 10 MHz-500 MHz range. It is useful to measure the MPI of the ECL in isolation and values + +typically are $< -55$ dB. Output should be taken through a standard single-mode fibre (ITU-T G.652 type) with an angled connector. + +![Schematic of set-up for narrowband ECL/PM method. The diagram shows a Tunable ECL connected to a Polarization scrambler, which is connected to a Mode stripper. The Mode stripper is connected to a 5 m ITU-T G.652 (15 cm coil) fibre. This fibre is connected to a Jumper under test at point A. The Jumper under test is connected to another 5 m ITU-T G.652 (15 cm coil) fibre at point B. This fibre is connected to an RX (receiver). A Control and data acquisition instruments box is connected to the Tunable ECL and the RX. The connection between the two 5 m fibres is labeled 'Offset fusion splice or connector'. The diagram is labeled G.650.1(18)_FIV.1.](31b824cd2882d0c2f82022527d58ec28_img.jpg) + +Schematic of set-up for narrowband ECL/PM method. The diagram shows a Tunable ECL connected to a Polarization scrambler, which is connected to a Mode stripper. The Mode stripper is connected to a 5 m ITU-T G.652 (15 cm coil) fibre. This fibre is connected to a Jumper under test at point A. The Jumper under test is connected to another 5 m ITU-T G.652 (15 cm coil) fibre at point B. This fibre is connected to an RX (receiver). A Control and data acquisition instruments box is connected to the Tunable ECL and the RX. The connection between the two 5 m fibres is labeled 'Offset fusion splice or connector'. The diagram is labeled G.650.1(18)\_FIV.1. + +**Figure IV.1 – Schematic of set-up for narrowband ECL/PM method. Here the "RX" receiver consists of a power meter or a photodetector/oscilloscope pair** + +##### IV.1.2.2 Polarization scrambler + +Since the coupling at the connection points will be polarization dependent, power measurements should be made at many random polarizations of the incoming light. The polarization may be changed by use of a polarization controller (manual or electronic) or a scrambler. In the case of a controller, at least 100 randomized polarization states should be used for each wavelength measured (therefore the manual controller is not recommended). The use of the scrambler requires knowledge of the scrambling speed (degree/s change on the Poincaré sphere, or highest frequency component in the scrambling instrument). The power measurement should be made on a time scale that is short compared to the time for the polarization to change substantially. Power meters usually require $\sim 0.1 - 20$ ms to obtain a reading. Thus scrambling frequencies should be below the range $1 - 0.005$ kHz, depending on the averaging time chosen for the power meter. If the photodetector/OSA receiver is used (see clause IV.1.2.4 below) then the scrambling speed is virtually unlimited. The polarization scrambler should have angled connections. It is useful to test the combined ECL – scrambler combination for MPI. Typical results are $< -50$ dB. Verify that randomly distributed polarization states on the Poincaré sphere are obtained. + +##### IV.1.2.3 Mode stripping loop + +The single-mode fibre in the launch line should be looped to the appropriate dimension to eliminate all but the fundamental $LP_{01}$ mode propagation. An alternative is to use a long (several hundred metres) piece of ITU-T G.652 fibre to sufficiently attenuate the HOM. + +##### IV.1.2.4 Optical receiver + +The light should be received by a power meter or a photodetector/oscilloscope combination. The power meter averaging time should be adjusted so that power measurements are made rapidly compared to the time over which the polarization scrambler changes the polarization significantly. Linearity of the power meter at the power levels used in the test should be ensured. The power meter response should be corrected for the different wavelengths used in the test. Built-in software may allow the power meter to run in MIN-MAX mode or LOGGING mode to get power statistics. Data is collected at each wavelength until $> 100$ measured power values have been captured. + +The photodetector/oscilloscope combination allows very high scrambling rates to be used (thereby shortening the testing time). Operate at high optical power to minimize receiver noise (but verify linearity of the detector at these power levels). Use a vertical offset on the oscilloscope trace and expand the vertical scale to maximize signal capture. Do not average. Set the acquisition sample rate according to a polarization scrambling speed and maximize the number of samples (record length). Set the time base to either capture all data in a single trigger and identify maximum and minimum voltages or run multiple triggers with a fast time base and collect voltage extrema over a sequence of + +triggers. The oscilloscope data acquisition should be triggered in synchronism with the ECL wavelength steps. + +#### IV.1.3 Measurements procedure + +##### IV.1.3.1 Preparation of the fibre under test + +If the short cable (fibre) to be tested has connectors, make sure proper cleaning procedures are followed. Choose a cable length to be tested and connectorize the ends or prepare the ends for fusion splice. + +##### IV.1.3.2 Baseline measurement + +This step identifies the lowest MPI the test set-up is capable of measuring. In addition, the average transmitted power obtained here is useful in removing the light source power variation with wavelength as prescribed in clause IV.1.3.5. + +Before including the test cable in the measurement set-up, measure a baseline response by connecting the polarization scrambler and RX in Figure IV.1 with either a 10 m long ITU-T G.652 fibre or two connectorized 5 m ITU-T G.652 fibres. Angled connectors should be used for both ends of the ITU-T G.652 fibre. Sweep the wavelength (over a range of roughly $\pm 3$ nm) in steps small enough to resolve the interference fringes expected in the test cable (iteration might be required, or use a small step such as 0.02 nm). At each wavelength capture the minimum, maximum and average power for $>100$ randomized polarization values. Use a wide enough wavelength scan to capture the free spectral range (FSR) of the jumper interference pattern. Since the FSR is not known before the jumper is measured, the baseline measurement might need to be repeated after a jumper measurement has been performed. + +##### IV.1.3.3 Insert short-cabled fibre + +Either disconnect the two 5 m ITU-T G.652 fibres or cut the ITU-T G.652 fibre at its centre and insert the test cable into the set-up (between points A and B in Figure IV.1), and characterize splice/connector losses at each end. Intentional offset fusion splices are a convenient way to obtain a desired connection loss. An alternative is to use offset connectors. When the MFD values of ITU-T G.652 fibre and test fibre are $9.0 \pm 0.5$ $\mu\text{m}$ at 1310 nm, an offset of 1-2 $\mu\text{m}$ corresponds to a connection loss of 0.5-1 dB (this loss should be directly measured). The coupling ratio of LP01 power in the 5 m ITU-T G.652 fibre lead to LP01 power in the test cable is desired for both connection points. It may be necessary to use mode filters and trial and error to eliminate the higher order modes (see the following note for more details). The geometrical layout of the test cable may be substantially straight, as this is the configuration which will generally give worst case MPI results. Other, more preferable, configurations can be tested as well, which involve multiple small radius cable bends. + +NOTE – The meaning of the MPI value obtained from this measurement is unclear without accurate knowledge of the LP01 loss through each of the connection points. Stripping of the high-order mode is required to determine this loss. Some additional comments are made here on mode stripping in ITU-T G.657 fibres. Some ITU-T G.657.A fibres may be mode stripped by using a suitably small fibre loop (the loop should not be so small that it attenuates the LP01 mode). If this is the case for the fibre under test, the first connection is made while monitoring the power through the jumper with a mode stripping loop present. When the first connection is satisfactory, the second connection is made, again with mode stripping loops present and power through the 5 m ITU-T G.652 fibre jumper is monitored until the total loss (through both splices) is satisfactory. + +Some ITU-T G.657.A fibres and all ITU-T G.657.B fibres cannot be mode stripped with fibre loops. However, these fibres generally do have a substantial HOM loss with fibre length (even when straight). Lengths required to strip out the HOM may be several hundred metres for some fibre types. In this case the first offset connection is made between the 5 m ITU-T G.652 fibre and a spool of the desired jumper fibre. Accounting for the LP01 loss through the spool (this may be measured separately using an aligned splice to the ITU-T G.652 launch fibre) the offset connection is adjusted until the desired LP01 loss is obtained. The spooled test fibre is now cut back to the desired jumper length and + +connectorized or fusion spliced to the output 5 m ITU-T G.652 fibre. Loss through this second connection point is found by monitoring power at the RX and comparing with LP01 input power minus the first connection LP01 loss. + +In either case, LP01 loss data should be taken over the FSR ( $\sim \pm 3$ nm) of the jumper interference pattern. The average over this wavelength range is the connection loss. For consistency, it is important to equalize the splice loss at each end of the test cable. This is because, for a fixed total loss in the splices, maximum MPI is found when the individual splice losses are equal. + +##### IV.1.3.4 Short-cabled fibre measurement + +The measurement procedure of clause IV.1.3.2 is followed. With the jumper under test included, ensure that the wavelength scan range is sufficient to encompass several cycles of the roughly sinusoidal variation in transmitted power of the FSR. In addition, ensure that the wavelength step is sufficiently small to resolve the spectral intensity pattern. + +#### IV.1.3.5 Calculations + +Though not mandatory, it is informative to first subtract the baseline average power from the maximum and minimum power measured through the test cable. This corrects for the power variation with wavelength of the light source. To compute the MPI, the data (corrected maximum and minimum transmitted power versus wavelength) is processed through a moving window of width $\geq$ FSR. For each position of the window (denoted by its central wavelength), the maximum and minimum power are found and used in Equation IV-1 to find the MPI. + +$$MPI(dB) = 20 \log \left[ \frac{10^{PR/20} - 1}{10^{PR/20} + 1} \right] \quad (IV-1)$$ + +where PR is the difference between the maximum and minimum power levels detected (in dB). Note that if the photodetector/oscilloscope method is used, the output data is an electrical voltage, not an optical power. Due to the linearity of the photodetector, Equation IV-1 can still be used with a voltage difference when voltages have been converted to dB ( $10 \log V$ ). Dark current corrections should be made prior to this conversion. Verify that the MPI, computed directly from the baseline data, is suitably low. + +##### IV.1.3.6 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement; +- b) optical source characteristics; +- c) polarization scrambling rate; +- d) fibre identification (cabled or uncabled), length, insertion loss and splice loss; +- e) methodology for measuring insertion/splice loss; +- f) geometrical layout of test cable; +- g) receiver characteristics (including signal acquisition time); +- h) table of MPI versus wavelength; +- i) after data is taken for a number of fibres of a given design, a mapping between the cut-off wavelength and MPI noise may be compiled. + +### IV.2 Second test method: The wideband LED/OSA technique + +#### IV.2.1 General + +The wideband LED/OSA technique monitors transmitted optical power through the jumper under test as a function of wavelength. The interference phenomenon between the fundamental, LP01, and HOM + +is measured by capturing the maximum and minimum transmitted power over a range of wavelengths. Polarization variation of the input is used to ensure true power extremes are found. + +#### IV.2.2 Test apparatus + +A schematic of the apparatus required for the second test method is shown in Figure IV.2. + +##### IV.2.2.1 Optical source + +A wideband light source (typically LED-based) with peak power density $> -40$ dBm/nm and stability $< \pm 0.03$ dB/15 minutes with output in the wavelength range of interest (usually 1260-1625 nm). Note that the stability of this source will not be as good as the ECL used in the first test method. This limits the lowest MPI which can be measured. It is useful to measure the MPI of the wideband source in isolation and values typically are $< -40$ dB across the full spectral band. Output should be taken through ITU-T G.652 fibre. Angled connectors should be used when available. + +![Schematic of set-up for the wideband LED/OSA method.](b69a80a8520eebfdd4ad580cd69beb8d_img.jpg) + +``` + + graph LR + BLS[Broadband light source] --> P[Polarizer] + P --> PS[Polarization scrambler] + PS --> MS[Mode stripper] + MS --> C1[5 m ITU-T G.652 +15 cm coil] + C1 --> A((A)) + A -- Jumper under test --> B((B)) + B --> C2[5 m ITU-T G.652 +15 cm coil] + C2 --> OSA[OSA] + OSA --> DA[Data acquisition] + + subgraph " " + A + B + end + + OFS[Offset fusion splice +or connector] -.-> A + OFS -.-> B + +``` + +The diagram illustrates the experimental setup for the wideband LED/OSA method. A 'Broadband light source' feeds into a 'Polarizer', followed by a 'Polarization scrambler'. The signal then passes through a 'Mode stripper' and a '5 m ITU-T G.652 (15 cm coil)'. Point 'A' marks the start of the 'Jumper under test', which ends at point 'B'. Both points A and B are described as an 'Offset fusion splice or connector'. After point B, the signal goes through another '5 m ITU-T G.652 (15 cm coil)' into an 'OSA' (Optical Spectrum Analyzer), which is connected to a 'Data acquisition' unit. The diagram is indexed as G.650.1(18)\_FIV.2. + +Schematic of set-up for the wideband LED/OSA method. + +**Figure IV.2 – Schematic of set-up for the wideband LED/OSA method. The polarizer is not necessary if the broadband light source has an internal polarizer** + +##### IV.2.2.2 Polarization scrambler + +Since the coupling at the connection points will be polarization dependent, OSA power density measurements should be made at many random polarizations of the incoming light. The polarization may be changed by use of a polarization controller (manual or electronic) or a scrambler. In the case of a controller, at least 100 randomized polarization states should be used for each wavelength measured (therefore a manual controller is not recommended). The use of the scrambler requires knowledge of the scrambling speed (degree/sec change on the Poincaré sphere, or highest frequency component in the scrambling instrument). The OSA power density measurement at each wavelength should be made on a time scale which is short compared to the time for the polarization to change substantially. Adjustment of the number of wavelengths tested, the sweep speed and the sensitivity allows the user to vary the acquisition time of the OSA to match the speed of the polarization scrambler. Note that only slow scrambling speeds are possible. The polarization scrambler should have angled connections. It is useful to test the LED – scrambler combination for MPI. Verify that randomly distributed polarization states on the Poincaré sphere are obtained. + +##### IV.2.2.3 Mode stripping loop + +See clause IV.1.2.3. + +##### IV.2.2.4 Optical receiver + +The OSA should be configured with the correct number of wavelength points and the sweep time so that the residence time at each wavelength is much shorter ( $\sim 10$ times) than the inverse of the polarization scrambling speed. This prevents polarization averaging during OSA measurement at each wavelength. Choose the vertical scale to maximize the signal. Measurements are taken using the **MAXIMUM** and **MINIMUM** power density functions on the OSA (if available). Resolution bandwidth should be 0.1 nm or less and the number of wavelength points should be sufficient to resolve the interference fringes over the FSR. + +#### **IV.2.3 Measurements procedure** + +##### **IV.2.3.1 Preparation of the fibre under test** + +See clause IV.1.3.1. + +##### **IV.2.3.2 Baseline measurement** + +Before including the test cable in the measurement set-up, measure a baseline response by connecting the polarization scrambler and OSA in Figure IV.2 with a 10 m long ITU-T G.652 fibre. With the OSA configured with the correct number of wavelengths, sweep speed, resolution bandwidth and vertical scale, apply averaging and measure the baseline response. Maxima and minima can also be measured if baseline MPI data is desired. Save the averaged trace for use later in removing the spectral dependency of the power output from the LED source. + +##### **IV.2.3.3 Insert short-cabled fibre** + +See clause IV.1.3.3. + +#### **IV.2.3.4 Short-cabled fibre measurement** + +Procedure if OSA has MAX power and MIN power trace capabilities: Put the OSA into MAX trace mode. Allow > 100 sweeps to get the highest signal at each wavelength with respect to input polarization. Save this trace and perform the same test with the MIN trace mode (some OSA models can perform these acquisitions simultaneously). Subtract the baseline trace found in clause IV.2.3.2 from the MAX trace result and from the MIN trace result. Output the resulting two traces. + +Procedure if the OSA does not perform MAX power and MIN power data manipulation internally: Take > 100 sweeps and output the data from each one to a control computer. Use the computer to sort out the maximum and minimum for each wavelength. The baseline can either be subtracted on the OSA or during data sorting on the computer. + +#### **IV.2.3.5 Calculations** + +See clause IV.1.3.5. + +##### **IV.2.3.6 Presentation of the results** + +See clause IV.1.3.6. + +### **IV.3 Third test method: The fibre stretching technique** + +#### **IV.3.1 General** + +The fibre stretching technique utilizes the fact that the transmitted power, with interference between the LP01 mode and an HOM in the jumper, changes periodically with the optical phase difference through the jumper. This optical phase difference is dependent on wavelength (which was exploited in the other two techniques) but is also proportional to the jumper length. The length is most easily varied by stretching the fibre. In this case the maximum and minimum transmitted power is measured as fibre length is varied. Polarization variation of the input is used to ensure true power extremes are found. For typical fibres with a 2 nm FSR, the required length variation is of the order of 2-4 mm; for a fibre span of 2 metres this corresponds to a strain of $\sim 10^{-3}$ , substantially below proof test levels. Higher strains may be required for fibres with a larger FSR. This method may be less easily applied in cases where the jumper is buffered and/or jacketed. + +### **IV.3.2 Test apparatus** + +A schematic of the apparatus required for the third test method is shown in Figure IV.3. The source can be either a tuneable laser or a transceiver. Polarization changes are made by the polarization scrambler. Angled connectors are used throughout to minimize reflections. The upstream fusion + +splice is attached to a fixed stage, while the other fusion splice is attached to a movable translation stage. + +![Schematic of set-up for the fibre stretching method. The diagram shows a light source connected to a polarization scrambler, which is connected to a 5 m single mode fibre (15 cm coil) via a mode stripper. This fibre is connected to an offset fusion splice or connector, which is connected to a jumper under test. The jumper under test is connected to another offset fusion splice or connector, which is connected to a translation stage (TS). The TS is connected to a 5 m single mode fibre (15 cm coil), which is connected to a receiver (RX). The RX is connected to a data acquisition unit. The diagram is labeled G.650.1(18)_FIV.3.](e9f6a9e6beb9ae97b392bf38b93ad748_img.jpg) + +Schematic of set-up for the fibre stretching method. The diagram shows a light source connected to a polarization scrambler, which is connected to a 5 m single mode fibre (15 cm coil) via a mode stripper. This fibre is connected to an offset fusion splice or connector, which is connected to a jumper under test. The jumper under test is connected to another offset fusion splice or connector, which is connected to a translation stage (TS). The TS is connected to a 5 m single mode fibre (15 cm coil), which is connected to a receiver (RX). The RX is connected to a data acquisition unit. The diagram is labeled G.650.1(18)\_FIV.3. + +**Figure IV.3 – Schematic of set-up for the fibre stretching method. "TS" is a translation stage. Here the "RX" receiver consists of a power meter or a photodetector/oscilloscope pair** + +##### IV.3.2.1 Optical source + +If a tuneable laser is used, the laser performance should conform to the specifications given in clause IV.1.2.1. Alternatively, an optical transceiver may be used. In either case, ensure that wavelength and power output are stable over the several minutes required for performing the test. If an optical transceiver can be chosen which is comparable to that used in the actual deployed system, the MPI results are particularly relevant. + +If a transceiver (e.g., a DFB one) with optical properties equivalent to those of the tuneable laser described in clause IV.1.2.1 is employed, the results will be substantially source-independent; otherwise (e.g., if a Fabry-Perot transceiver is used) the results may depend on the transceiver properties. + +#### IV.3.2.2 Measurement settings + +##### IV.3.2.2.1 Polarization scrambler + +To ensure that worst-case conditions are achieved, transmitted power measurements should be made at many random polarizations of the incoming light. The polarization may be changed by using a polarization controller (manual or electronic) or a scrambler, preferably with angled connections. The use of the scrambler requires knowledge of the scrambling speed (degree/s change on the Poincaré sphere, or highest frequency component in the scrambling instrument). The scrambling speed should be slow enough to guarantee that each power meter measurement is completed before there is significant polarization change. In other terms, the time employed by the scrambler to produce an appreciable polarization change should be longer than the power meter integration time, to avoid that the power variations induced by polarization scrambling are averaged-out by the power meter integration time. So, with a power meter integration time of 100 ms, a scrambling frequency of 5 Hz should be used, meaning that a substantial variation of the polarization takes place in 200 ms. + +##### IV.3.2.2.2 Translation stage + +The translation length should be set after the mode beating period has been determined, which should be done with the polarization scrambling turned off. The translation length should be chosen between a lower limit dictated by the periodicity of the mode beating (two periods is recommended) and an upper limit corresponding to an appropriate fibre strain. In the case of a two-metre cable sample, the lower limit of the translation length would be ~2 mm and the upper limit would be ~20 mm. The velocity of the translation stage should be slow enough to guarantee that the time employed for a complete peak/trough cycle is much longer than the power meter integration time, to avoid that the power oscillations induced by fibre length variation are averaged-out by the power meter integration time. As an example, a translation velocity of 0.2 mm/s would complete a peak/trough cycle of 1 mm in 5 s, much longer than the power meter integration time of 100 ms. + +##### **IV.3.2.2.3 Sampling frequency** + +Once the power meter integration time, the speed of the scrambling, the translation stage velocity and its excursion have been set in accordance with the criteria exposed in the previous two points, the frequency of the power meter acquisitions should be decided. The sampling frequency should be high enough to guarantee a clear identification of the peak/trough cycle determined by the fibre stretching, with no less than 25 points collected for each oscillation period. However, the time distance between two consecutive acquisitions should be greater than the power meter integration time, to ensure that they correspond to truly different interference and polarization states. Namely, an acquisition every 200 ms would be compatible with the parameter values exemplified in the previous (a)-(b) points. + +##### **IV.3.2.2.4 Number of measurements** + +A reliable MPI evaluation can be obtained only if a large enough number of power meter readings, corresponding to a different polarization state of the injected light and phase differences between the co-propagating mode, are collected. With the suggested parameter values, a translation length of 4 mm, corresponding to 4 beating periods, would provide 100 power meter readings and would take 20 seconds. To assess the reliability of the resulting MPI value, this measurement should be repeated at least 20 times, so that in 400 seconds 20 different MPI values can be calculated, having collected a total of 2000 power meter readings corresponding to a different state of the injected light polarization and of the mode phase different. The average and the standard deviation of the collected MPI values provide a complete statistical description of the expected penalty. + +##### **IV.3.2.2.5 Using a manual polarization scrambler** + +If a manual scrambler is to be used, as a preliminary step it is necessary to test the light source – scrambler combination to verify that randomly distributed polarization states on the entire Poincaré sphere are obtained. In this case, instead of continuously scrambling the polarization while the fibre stretching takes place, it could be easier to change the polarization after every translation run. Assuming that 100 power meter acquisitions are made during each run, and that 20 runs are performed with 20 different polarization states, the MPI can be calculated on a total of 2000 power meter readings. + +##### **IV.3.2.3 Mode stripping loop** + +See clause IV.1.2.3. + +##### **IV.3.2.4 Optical receiver** + +See clause IV.1.2.4. + +#### **IV.3.3 Measurements procedure** + +##### **IV.3.3.1 Preparation of the fibre under test** + +This test method employs an uncabled fibre jumper with offset fusion splices at the ends. The fibre is nominally 2 m in length and the splice losses should be individually characterized (see clause IV.1.3.3). + +##### **IV.3.3.2 Baseline measurement** + +Before including the test fibre in the measurement set-up, measure a baseline response by connecting the polarization scrambler and RX in Figure IV.3 with a 10 m long ITU-T G.652 fibre and stretching 2 m of it without affecting the splice/connection loss. + +##### IV.3.3.3 Insert short fibre test sample + +The test fibre may be attached using paper tape to the translation stages. It is recommended that the fibre be straight, with the tape covering ~ 10 cm of fibre at either side of the fusion splice (covering the splice for protection). The fibre between the stages is usually ~2 m in length and under slight tension (straight). + +##### IV.3.3.4 Short-cabled fibre measurement + +With the light source and polarization scrambler active, the translation stage is moved in small increments. With each movement, the transmitted power is recorded along with the position of the stage. The stage movement should be sufficient to eventually allow exploration of two FSR of the test fibre (the transmitted power versus fibre length goes through two maxima and minima). At this point the stage reverses direction and more data is taken. This process continues until enough polarization states have been sampled (~100) at each fibre length. If desired, the light source wavelength can be slowly varied as well. + +##### IV.3.3.5 Calculations + +Find the MPI by determining the maximum and minimum power transmitted through the sample over all fibre stretch lengths and polarization states; then use the formula from Equation IV-1, repeated below: + +$$MPI(dB) = 20 \log \left[ \frac{10^{PR/20} - 1}{10^{PR/20} + 1} \right] \quad (IV-1)$$ + +where PR is the difference between the maximum and minimum power levels detected (in dB). Note that if the photodetector/oscilloscope method is used, the output data is an electrical voltage, not an optical power. Due to the linearity of the photodetector, Equation IV-1 can still be used with a voltage difference when voltages have been converted to dB (10 log V). Dark current corrections should be made prior to this conversion. Verify that the MPI, computed directly from the baseline data, is suitably low. + +##### IV.3.3.6 Presentation of the results + +See clause IV.1.3.6. + +# Appendix V + +## The interferometric technique for chromatic dispersion measurement + +(This appendix does not form an integral part of this Recommendation.) + +### V.1 General + +The interferometric test method allows the chromatic dispersion to be measured, using a short piece of fibre (several metres). This offers the possibility of measuring the longitudinal chromatic dispersion homogeneity of optical fibres. Moreover, it is possible to test the effect of overall or local influences, such as temperature changes and macrobending losses, on the chromatic dispersion. + +According to the interferometric measuring principle, the wavelength-dependent time delay between the test sample and the reference path is measured by a Mach-Zehnder interferometer. The reference path can be an air path or a single-mode fibre with known spectral group delay. + +It should be noted that extrapolation of the chromatic dispersion values derived from the interferometric test on fibres of a few metres length, to long fibre sections assumes longitudinal homogeneity of the fibre. This assumption may not be applicable in every case. + +### V.2 Test apparatus + +Schematic diagrams of the test apparatus using a reference fibre and an air path reference are shown in Figures V.1 and V.2, respectively. + +![Schematic diagram of measurement set-up with reference fibre (Figure V.1).](99e9a4791d2e5bb5afa1bb884652d4db_img.jpg) + +The diagram illustrates a Mach-Zehnder interferometer setup for chromatic dispersion measurement. A light source emits a signal that passes through a wavelength selector. The output is split by 'Beam splitter 1' into two paths: a 'Test fibre' and a 'Reference fibre'. Both fibres are coiled. The 'Reference fibre' path includes a 'Linear positioning device' that can move a mirror to adjust the 'Positioning distance x'. The two paths recombine at 'Beam splitter 2'. The output of the beam splitter is detected by a 'Detector', which sends a signal to a 'Lock-in amplifier'. A 'Reference signal' from the light source is also fed into the lock-in amplifier. The diagram is labeled 'G.650.1(18)\_FV.1'. + +Schematic diagram of measurement set-up with reference fibre (Figure V.1). + +a) When needed + +**Figure V.1 – Schematic diagram of measurement set-up with reference fibre** + +![Schematic diagram of measurement set-up with air path reference. The diagram shows a light source connected to a wavelength selector. The output of the wavelength selector is split by 'Beam splitter 1'. One path goes through an 'Optical delay line' and then to 'Beam splitter 2'. The other path from 'Beam splitter 1' goes to a 'Linear positioning device' which moves a mirror. The reflected path goes to 'Beam splitter 2'. The 'Test fibre' is connected to 'Beam splitter 2'. The output of the 'Test fibre' goes to a 'Detector'. A 'Reference signal' is fed into the 'Detector' from the 'Lock-in amplifier'. The 'Lock-in amplifier' is also connected to the 'Detector'. The 'Air path' is the distance between 'Beam splitter 1' and 'Beam splitter 2'. The 'Positioning distance x/2' is the distance between the 'Linear positioning device' and 'Beam splitter 2'.](5cc4a2ef554f31ea0577731931007fff_img.jpg) + +Schematic diagram of measurement set-up with air path reference. The diagram shows a light source connected to a wavelength selector. The output of the wavelength selector is split by 'Beam splitter 1'. One path goes through an 'Optical delay line' and then to 'Beam splitter 2'. The other path from 'Beam splitter 1' goes to a 'Linear positioning device' which moves a mirror. The reflected path goes to 'Beam splitter 2'. The 'Test fibre' is connected to 'Beam splitter 2'. The output of the 'Test fibre' goes to a 'Detector'. A 'Reference signal' is fed into the 'Detector' from the 'Lock-in amplifier'. The 'Lock-in amplifier' is also connected to the 'Detector'. The 'Air path' is the distance between 'Beam splitter 1' and 'Beam splitter 2'. The 'Positioning distance x/2' is the distance between the 'Linear positioning device' and 'Beam splitter 2'. + +a) When needed + +G.650.1(18)\_FV.2 + +**Figure V.2 – Schematic diagram of measurement set-up with air path reference** + +#### V.2.1 Optical source + +The source should be stable in position, intensity and wavelength for a time period sufficiently long to complete the measurement procedure. The source should be suitable, e.g., a YAG laser with a Raman fibre or a lamp and LED optical sources, etc. For the application of lock-in amplification techniques, a light source with low-frequency modulation (50 to 500 Hz) is sufficient. + +### V.2.2 Wavelength selector + +A wavelength selector is used to select the wavelength at which the group delay is measured. A monochromator, optical interference filter, or other wavelength selector may be used depending on the type of optical sources and measurement systems. The wavelength selector may be used either at the input or the output end of the fibre under test. + +The spectral width of the optical sources is to be restricted by the dispersion measuring accuracy, and it is about 2 to 10 nm. + +If a mathematical fit is made to the data, at least one data point should be within 100 nm of $\lambda_0$ . + +#### V.2.3 Optical detector + +The optical detector should have a sufficient sensitivity in that wavelength range in which the chromatic dispersion has to be determined. If necessary, the received signal could be upgraded with, for example, a transimpedance circuit. + +#### V.2.4 Test equipment + +For the recording of the interference patterns, a lock-in amplifier may be used. Balancing of the optical length of the two paths of the interferometer is performed with one linear positioning device in the reference path. Concerning the positioning device, attention should be paid to the accuracy, uniformity and stability of linear motion. The variation of the length should cover the range from 20 to 100 mm with an accuracy of about 2 $\mu\text{m}$ . + +#### V.2.5 Specimen + +The specimen for the test can be uncabled and cabled single-mode fibres. The length of the specimen should be in the range 1 m to 10 m. The accuracy of the length should be about $\pm 1$ mm. The preparation of the fibre end faces should be carried out with reasonable care. + +### V.2.6 Data processing + +For the analysis of the interference patterns, a computer with suitable software should be used. + +### V.3 Measurement procedure + +- 1) The fibre under test is placed in the measurement set-up (Figures V.1 and V.2). The positioning of the end faces is carried out with 3-dimensional micro-positioning devices by optimizing the optical power received by the detector. Errors arising from cladding modes are not possible. +- 2) The determination of the group delay is performed by balancing the optical lengths of the two interferometer paths with one linear positioning device in the reference path for different wavelengths. The difference between position $x_i$ of the maximum of the interference pattern for wavelength $\lambda_i$ and position $x_0$ for wavelength $\lambda_0$ (Figures V.3) determines the group delay difference $\Delta\tau_g(\lambda_i)$ between the reference path and the test path as follows: + +$$\Delta\tau_g(\lambda_i) = \frac{x_0 - x_i}{c_0} \quad (\text{V-1})$$ + +where $c_0$ is the velocity of light in the vacuum. The group delay of the test sample is calculated by adding the value $\Delta\tau_g(\lambda_i)$ and the spectral group delay of the reference path. Dividing this sum by the test fibre length then gives the measured group delay difference per unit length $\tau(\lambda)$ of the test fibre. + +![Figure V.3: Determination of the spectral group delay. The figure consists of two plots. The left plot shows interference patterns for wavelengths λ₀, λ₁, and λₙ. The x-axis represents position x (mm) and group delay t_g (ps). The right plot shows the relative group delay (ps) versus wavelength λ (nm) for a reference fibre and a test fibre. The reference fibre curve is relatively flat near zero, while the test fibre curve shows significant dispersion, dipping to around -7 ps at 1400 nm and rising to about 4 ps at 1800 nm. Vertical arrows indicate the group delay differences Δτ_g(λ₁), Δτ_g(λ₂), and Δτ_g(λ₃) at specific wavelengths.](993d36ea4a6a2610f938b1fb97e7c34a_img.jpg) + +The figure contains two plots. The left plot shows three interference patterns for wavelengths $\lambda_0$ , $\lambda_1$ , and $\lambda_n$ . The horizontal axis represents position $x$ in mm and group delay $t_g$ in ps. The peak of the $\lambda_0$ pattern is at position $x_0$ , the peak of the $\lambda_1$ pattern is at $x_1$ , and the peak of the $\lambda_n$ pattern is at $x_n$ . Horizontal double-headed arrows indicate the group delay differences $\Delta\tau_g(\lambda_1)$ and $\Delta\tau_g(\lambda_n)$ between the $\lambda_0$ peak and the other peaks. The right plot shows the 'Relative group delay' in ps on the y-axis (ranging from -10 to 10) against 'Wavelength $\lambda$ (nm)' on the x-axis (ranging from 1200 to 1800). It features two curves: a 'Reference fibre' curve that stays near 0 ps, and a 'Test fibre' curve that dips to about -7 ps at 1400 nm and rises to about 4 ps at 1800 nm. Vertical arrows from the x-axis to the curves indicate $\Delta\tau_g(\lambda_1)$ , $\Delta\tau_g(\lambda_2)$ , and $\Delta\tau_g(\lambda_3)$ at approximately 1250 nm, 1350 nm, and 1450 nm respectively. The text 'G.650.1(18)\_FV.3' is in the bottom right corner. + +Figure V.3: Determination of the spectral group delay. The figure consists of two plots. The left plot shows interference patterns for wavelengths λ₀, λ₁, and λₙ. The x-axis represents position x (mm) and group delay t\_g (ps). The right plot shows the relative group delay (ps) versus wavelength λ (nm) for a reference fibre and a test fibre. The reference fibre curve is relatively flat near zero, while the test fibre curve shows significant dispersion, dipping to around -7 ps at 1400 nm and rising to about 4 ps at 1800 nm. Vertical arrows indicate the group delay differences Δτ\_g(λ₁), Δτ\_g(λ₂), and Δτ\_g(λ₃) at specific wavelengths. + +Figure V.3 – Determination of the spectral group delay + +### V.4 Presentation of the results + +The following details should be presented: + +- a) test set-up arrangement; +- b) source characteristics; +- c) fibre identification and length; +- d) characteristics of the wavelength selector (if present); +- e) type of photodetector; + +- f) model used to fit the relative group delay data or chromatic dispersion data, and the fitting wavelength range used; +- g) values of coefficients from the fit for each fitting wavelength range; +- h) temperature of the sample and environmental conditions (if necessary). + +# Bibliography + +- [b-ITU-T G.Sup.47] ITU-T G-series Recommendations – Supplement 47 (2012), *General aspects of optical fibres and cables*. +- [b-IEC/TR 62048] IEC/TR 62048 (2014), *Optical fibres – Reliability – Power law theory*. +- [b-Fleming] Fleming, J.W. (1978), *Material dispersion in lightguide glasses*, Electron. Lett., Vol. 14, No. 11, pp. 326-328. +- [b-Hanson] Hanson T.A. (1991), *Spectral Attenuation Modelling with Matrix Models*, Conference Digest NPL Optical Fibre Measurement Conference (OFMC'91), pp. 8-11, York, United Kingdom. +- [b-Kobayashi] Kobayashi S. *et al* (1977), *Refractive-index dispersion of doped fused silica*, IOOC 1977, pp. 309-312. +- [b-Press] Press, William H. (1993), *Numerical Recipes in C: The Art of Scientific Computing*, Cambridge University Press, 2nd edition. + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.650.2-201508-I_PDF-E/raw.md b/marked/G/T-REC-G.650.2-201508-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..7575ad5b3bfc406c55f7a491a4f0b6aca61166d2 --- /dev/null +++ b/marked/G/T-REC-G.650.2-201508-I_PDF-E/raw.md @@ -0,0 +1,2275 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.650.2** + +(08/2015) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Transmission media and optical systems characteristics – +Optical fibre cables + +--- + +**Definitions and test methods for statistical and +non-linear related attributes of single-mode fibre +and cable** + +Recommendation ITU-T G.650.2 + +# ITU-T G-SERIES RECOMMENDATIONS + +## TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| General | G.600–G.609 | +| Symmetric cable pairs | G.610–G.619 | +| Land coaxial cable pairs | G.620–G.629 | +| Submarine cables | G.630–G.639 | +| Free space optical systems | G.640–G.649 | +| Optical fibre cables | G.650–G.659 | +| Characteristics of optical components and subsystems | G.660–G.679 | +| Characteristics of optical systems | G.680–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +For further details, please refer to the list of ITU-T Recommendations. + +# Recommendation ITU-T G.650.2 + +# Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable + +## Summary + +Recommendation ITU-T G.650.2 contains definitions of the statistical and non-linear parameters of single-mode fibre and cable. It also contains both reference test methods and alternative test methods for characterizing these parameters. + +This edition of the Recommendation has removed the state of polarization (SOP) method (first alternative test method). + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.650 | 1993-03-12 | XV | 11.1002/1000/879 | +| 2.0 | ITU-T G.650 | 1997-04-08 | 15 | 11.1002/1000/4017 | +| 3.0 | ITU-T G.650 | 2000-10-06 | 15 | 11.1002/1000/5182 | +| 4.0 | ITU-T G.650.1 | 2002-06-29 | 15 | 11.1002/1000/6072 | +| 4.0 | ITU-T G.650.2 | 2002-06-29 | 15 | 11.1002/1000/6073 | +| 4.1 | ITU-T G.650.1 (2002) Amd. 1 | 2003-03-16 | 15 | 11.1002/1000/6259 | +| 4.1 | ITU-T G.650.2 (2002) Amd. 1 | 2003-03-16 | 15 | 11.1002/1000/6260 | +| 5.0 | ITU-T G.650.1 | 2004-06-13 | 15 | 11.1002/1000/7319 | +| 5.0 | ITU-T G.650.2 | 2005-01-13 | 15 | 11.1002/1000/7468 | +| 6.0 | ITU-T G.650.2 | 2007-07-29 | 15 | 11.1002/1000/9152 | +| 6.0 | ITU-T G.650.1 | 2010-07-29 | 15 | 11.1002/1000/10868 | +| 6.1 | ITU-T G.650.1 (2010) Amd. 1 | 2012-10-29 | 15 | 11.1002/1000/11767 | +| 6.2 | ITU-T G.650.1 (2010) Cor. 1 | 2013-08-29 | 15 | 11.1002/1000/11981 | +| 7.0 | ITU-T G.650.2 | 2015-08-13 | 15 | 11.1002/1000/12528 | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2015 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|----------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Terms and definitions ..... | 1 | +| 3.1 Polarization mode dispersion (PMD) ..... | 1 | +| 3.2 Types of test methods ..... | 7 | +| 4 Abbreviations and acronyms ..... | 7 | +| 5 Conventions ..... | 8 | +| 6 Test methods ..... | 8 | +| 6.1 Test methods for polarization mode dispersion..... | 9 | +| 6.2 Test methods for non-linear attributes..... | 35 | +| Appendix I – Determination of PMD delay from an interferogram ..... | 36 | +| I.1 RMS calculation for TINTY ..... | 36 | +| I.2 RMS calculation for GINTY ..... | 38 | +| Appendix II – Non-linear attributes ..... | 39 | +| II.1 Background..... | 39 | +| II.2 Effective area ( $A_{\text{eff}}$ )..... | 39 | +| II.3 Correction factor k..... | 40 | +| II.4 Non-linear coefficient ( $n_2/A_{\text{eff}}$ ) ..... | 42 | +| II.5 Stimulated Brillouin scattering..... | 43 | +| II.6 Other effects ..... | 52 | +| Appendix III – Test methods for effective area ( $A_{\text{eff}}$ ) ..... | 53 | +| III.1 The far-field scan (FFS) technique..... | 53 | +| III.2 The variable aperture (VA) technique ..... | 55 | +| III.3 The near-field scan (NFS) technique..... | 59 | +| Appendix IV – Information on polarization mode dispersion statistics ..... | 62 | +| IV.1 Introduction ..... | 62 | +| IV.2 Data collection..... | 63 | +| IV.3 Calculation of $\text{PMD}_Q$ (Monte Carlo)..... | 63 | +| IV.4 Calculation for $\text{DGD}_{\text{max}}$ (Monte Carlo)..... | 63 | +| Bibliography..... | 65 | + + + +# Recommendation ITU-T G.650.2 + +## Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable + +# 1 Scope + +This Recommendation contains definitions and test methods suitable mainly for factory measurements of the statistical and non-linear attributes of the single-mode optical fibres and cables described in [\[b-ITU-T G.652\]](#), [\[b-ITU-T G.653\]](#), [\[b-ITU-T G.654\]](#), [\[b-ITU-T G.655\]](#), [\[b-ITU-T G.656\]](#), and [\[b-ITU-T G.657\]](#). These definitions and test methods are generally not appropriate for multimode fibre, such as that described in [\[b-ITU-T G.651.1\]](#). Some of the test methods, when so indicated, may also be used to characterize discrete optical components, such as those described in [\[b-ITU-T G.671\]](#). [\[b-ITU-T G.650.1\]](#) contains definitions and test methods for linear deterministic attributes. + +Methods to compensate for impairments caused by polarization mode dispersion (PMD) can be found in [\[b-ITU-T G.666\]](#). + +## 2 References + +None. + +## 3 Terms and definitions + +This Recommendation defines the following terms (for more background information see [\[b-IEC/TR 61282-9\]](#)): + +## 3.1 Polarization mode dispersion (PMD) + +**3.1.1 phenomenon of PMD:** The differential group delay (DGD) time between two orthogonal polarized modes, which causes pulse spreading in digital systems and distortions in analogue systems. + +NOTE 1 – In ideal circular symmetric fibres, the two polarization modes propagate with the same velocity. However, real fibres cannot be perfectly circular and can undergo local stresses; consequently, the propagating light is split into two local polarization modes travelling at different velocities. These asymmetry characteristics vary randomly along the fibre and in time, leading to a statistical behaviour of PMD. A "maximum" value of DGD can be inferred from the statistics. + +NOTE 2 – For a given arbitrarily deployed fibre at a given time and optical frequency, there always exist two polarization states, called principal states of polarization (PSPs; see clause 3.1.2) such that the pulse spreading due to PMD vanishes if only one PSP is excited. Conversely, the maximum pulse spread due to PMD occurs when both PSPs are equally excited, and is related to the difference in the group delays associated with the two PSPs. + +**3.1.2 principal states of polarization (PSPs):** When operating an optical fibre at a wavelength longer than the cut-off wavelength in a quasi-monochromatic regime, the output PSPs are the two orthogonal output states of polarization for which the output polarizations do not vary when the optical frequency is varied slightly. The corresponding orthogonal input polarization states are the input PSPs. + +NOTE 1 – The local birefringence changes along the fibre, and the PSP depends on the fibre length (contrary to high-birefringence). + +NOTE 2 – The PSPs are random complex vectors depending on time and optical frequency. However, according to the definition, there exists a small frequency range, the PSP bandwidth, over which they can be considered practically constant. + +NOTE 3 – If a signal has a bandwidth broader than the PSP bandwidth, second order PMD effects come into play. They may imply a depolarization of the output field, together with an additional chromatic dispersion effect. + +**3.1.3 differential group delay (DGD); [ $\Delta\tau(v)$ in ps]:** The time difference in the group delays of the PSPs. + +The DGD between two PSPs is wavelength-dependent and can vary randomly in time due to random mode coupling and randomized stresses along the optical propagation path due, among other causes, to environmental conditions. Variations in the order of a factor of two are typical for normal transmission fibres. As the PMD increases, the variance of the DGD values increases and the characteristic periodicity also decreases. For normal random-mode-coupled fibre, the DGD distribution is ergodic, which means that the distribution remains the same over time and wavelength, for a sufficiently long period or wide range. This allows an assumption that measurements over a finite wavelength range are representative of other wavelength ranges or the same wavelength range at different times over a long period of time. For mode-coupled fibres, the distribution is usually Maxwellian. + +Instantaneous DGD values limit the transmission capacity of digital systems. The derivative of the DGD with respect to the wavelength limits the signal-to-noise ratio (SNR) in analogue systems. Therefore, the statistical distribution of the DGDs (vs time or vs wavelength) plays an important role in predicting real system performance. + +Negligible mode coupling is found on some specialty fibre, such as polarization-maintaining fibre (PMF), and some components. For these devices, there is very little DGD variation with wavelength. + +The DGD is measured in picoseconds. + +**3.1.4 PMD value:** $\text{PMD}_{\text{AVG}}$ is defined as the linear average $\langle\Delta\tau\rangle$ of the DGD values $\Delta\tau(v)$ over a given optical frequency range $v_1$ to $v_2$ , + +$$\text{PMD}_{\text{AVG}} = \langle\Delta\tau\rangle = \frac{\int_{v_1}^{v_2} \Delta\tau(v) dv}{v_2 - v_1} \quad (3-1)$$ + +$\text{PMD}_{\text{RMS}}$ is defined as the root mean square (RMS) $\langle\Delta\tau^2\rangle^{1/2}$ of the DGD values $\Delta\tau(v)$ over a given optical frequency range $v_1$ to $v_2$ , + +$$\text{PMD}_{\text{RMS}} = \langle\Delta\tau^2\rangle^{1/2} = \left( \frac{\int_{v_1}^{v_2} \Delta\tau(v)^2 dv}{v_2 - v_1} \right)^{1/2} \quad (3-2)$$ + +NOTE 1 – For Equations 3-1 and 3-2 to be valid, the range $v_1$ to $v_2$ should be sufficiently wide, e.g., of the order of 100 nm in the corresponding wavelength range. + +If the distribution of these DGD values over the given optical frequency range may be approximated by a Maxwell distribution with sufficient amount of confidence and fidelity, $\text{PMD}_{\text{AVG}}$ can be mathematically related to $\text{PMD}_{\text{RMS}}$ . + +$$\langle\Delta\tau\rangle = \left( \frac{8}{3\pi} \right)^{1/2} \langle\Delta\tau^2\rangle^{1/2} \quad (3-3)$$ + +For fibre and cable, the PMD reference test method (RTM) reports the linear average. + +NOTE 2 – Averaging over temperature, time or mechanical perturbations is generally an acceptable alternative to averaging over frequency. In this case, the expected value operator is over all conditions. The expected value of a set of finite wavelengths at a given time is equal to the long-term expected value over any frequency range. Both Equations 3-1 and 3-2 are considered as an averaging in this context. + +NOTE 3 – Equation 3-3 applies only when the distribution of DGDs is Maxwellian, for instance, when the fibre is randomly mode coupled. The generalized use of Equation 3-3 can be verified by statistical analysis. A Maxwell distribution may not be the case if there are point sources of elevated birefringence (relative to the rest of the fibre), such as a tight bend, or other phenomena that reduce the mode coupling, such as a continual reduced bend radius with fibre in tension. In these cases, the distribution of the DGDs will begin to resemble the square root of a non-central Chi-square distribution with three degrees of freedom. For these cases, the $PMD_{RMS}$ value will generally be larger relative to the $PMD_{AVG}$ that is indicated in Equation 3-3. + +**3.1.5 PMD coefficient:** The PMD value normalized to the measurement length. + +There are two normalization formulas, one for random mode coupling, associated with normal transmission fibres, and one for negligible mode coupling, associated with specialty fibres such as polarization maintaining fibres. + +**3.1.5.1 random mode coupling:** For random mode coupling, the PMD coefficient is the PMD value ( $PMD_{AVG}$ or $PMD_{RMS}$ ) divided by the square root of the length ( $L^{1/2}$ ) and is usually reported in picoseconds per root kilometre. + +**3.1.5.2 negligible mode coupling:** For negligible mode coupling, the PMD coefficient is the PMD value ( $PMD_{AVG}$ or $PMD_{RMS}$ ) divided by the length ( $L$ ) and may be reported in picoseconds per kilometre or femtoseconds per metre. + +**3.1.6 mathematical definitions:** PMD can be described in terms of Stokes or Jones vectors. The evolution of the output Jones vector with angular optical frequency, $\omega = 2\pi\nu = 2\pi c/\lambda$ , is the source of system impairment. All parameters, vectors and matrices in the following are functions of angular optical frequency. + +For the following considerations it is assumed that the signal is fully polarized and that polarization dependent loss (PDL) is negligible. + +The normalized Jones vector $\vec{j}$ , with complex elements, $j_x$ and $j_y$ , is defined as: + +$$\vec{j} = \begin{bmatrix} \cos \theta \exp(-i\mu/2) \\ \sin \theta \exp(i\mu/2) \end{bmatrix} \quad (3-4)$$ + +where: + +$\theta$ is the linear orientation of the Jones vector + +$\mu$ is the phase separation of the two elements of the Jones vector + +$i$ is $\sqrt{-1}$ , the imaginary unit + +The normalized Stokes vector $\vec{s}$ in Cartesian coordinates, usually numbered 1, 2, 3, is defined as: + +$$\vec{s} = \begin{bmatrix} |j_x|^2 - |j_y|^2 \\ 2 \operatorname{Re}\{j_x j_y^*\} \\ -2 \operatorname{Im}\{j_x j_y^*\} \end{bmatrix} = \begin{bmatrix} \cos 2\theta \\ \sin 2\theta \cos \mu \\ \sin 2\theta \sin \mu \end{bmatrix} \quad (3-5)$$ + +where: + +$|j_x|^2 = j_x^* j_x$ is the squared magnitude of $j_x$ + +$j_y^*$ is the complex conjugate of $j_y$ . + +NOTE 1 – The minus sign for $s_3$ in (Equation 3-5) does result in Stokes vector rotations following the right hand rule. It does not affect the DGD measurements. + +Cartesian coordinates $s_1$ , $s_2$ and $s_3$ can be related to spherical coordinates $\psi$ and $\chi$ as follows: + +$$\begin{bmatrix} s_1 \\ s_2 \\ s_3 \end{bmatrix} = \begin{bmatrix} \cos \psi \cos \chi \\ \sin \psi \cos \chi \\ \sin \chi \end{bmatrix} \quad (3-6)$$ + +and, inversely, + +$$\tan \psi = \frac{s_2}{s_1} \quad (3-7)$$ + +$$\sin \chi = s_3 \quad (3-8)$$ + +where: + +$\psi$ is the longitude + +$\chi$ is the latitude + +NOTE 2 – Sometimes $\chi$ is defined as $\pi/2 - \chi$ . In this case, $\sin \chi$ must be replaced by $\cos \chi$ . + +From Equations 3-5 to 3-8, the Stokes vector in spherical coordinates $\psi$ and $\chi$ can be calculated as a function of $\theta$ and $\mu$ : + +$$\tan \psi = \tan 2\theta \cos \mu \quad (3-9)$$ + +$$\sin \chi = \sin 2\theta \sin \mu \quad (3-10)$$ + +For a given frequency, $\omega_0$ , the relationship between the input Stokes vector, $\vec{s}_0$ , to output vector can be described as a three-dimensional real rotation matrix, $R$ , with rotation angle, $\gamma_{\text{ROT}}$ , and rotation vector, $\vec{y}$ . + +$$\vec{s} = R\vec{s}_0 \quad \text{where } R = \vec{y} \vec{y}^T (1 - \cos \gamma_{\text{ROT}}) + I \cos \gamma_{\text{ROT}} + [\vec{y} \times] \sin \gamma_{\text{ROT}} \quad (3-11)$$ + +the rotation vector $\vec{y}$ is a column vector, consequently, $\vec{y}^T$ is a row vector and + +$$\vec{y} \vec{y}^T = \begin{bmatrix} y_1^2 & y_1 y_2 & y_1 y_3 \\ y_1 y_2 & y_2^2 & y_2 y_3 \\ y_1 y_3 & y_2 y_3 & y_3^2 \end{bmatrix} \text{ is a matrix, } I \text{ is the identity matrix and}$$ + +$$[\vec{y} \times] = \begin{bmatrix} 0 & -y_3 & y_2 \\ y_3 & 0 & -y_1 \\ -y_2 & y_1 & 0 \end{bmatrix} \text{ is the cross-product operator.}$$ + +At this frequency, the relationship of the output Jones vector to input vector, $\vec{j}_0$ , is given by the matrix, $T$ , as: + +$$\vec{j} = T\vec{j}_0 \quad \text{where } T = \begin{bmatrix} \cos \gamma_T - i y_1 \sin \gamma_T & -\sin \gamma_T (y_3 + i y_2) \\ \sin \gamma_T (y_3 - i y_2) & \cos \gamma_T + i y_1 \sin \gamma_T \end{bmatrix} \quad (3-12)$$ + +$\gamma_{\text{ROT}} = 2\gamma_T$ and the subscripted values are the elements of the rotation vector. + +The polarization dispersion vector (PDV), $\vec{\Omega}$ , is used to describe the variation of the output vectors with frequency. In the Stokes notation, it is defined as: + +$$\frac{d\vec{s}(\omega)}{d\omega}\bigg|_{\omega_0} = \frac{dR(\omega)}{d\omega}\bigg|_{\omega_0} R^T(\omega_0)\vec{s}(\omega_0) = \vec{\Omega} \times \vec{s}(\omega_0) \quad (3-13)$$ + +In the Jones notation, it is defined as follows, where the subscripted values are the elements of the PDV: + +$$\frac{d\vec{j}(\omega)}{d\omega}\bigg|_{\omega_0} = \frac{dT(\omega)}{d\omega}\bigg|_{\omega_0} T^T(\omega_0)\vec{j}(\omega_0) = -\frac{i}{2} \begin{bmatrix} \Omega_1 & \Omega_2 - i\Omega_3 \\ \Omega_2 + i\Omega_3 & -\Omega_1 \end{bmatrix} \vec{j}(\omega_0) \quad (3-14)$$ + +Equation 3-14 can be used as the basis of a first order Taylor expansion for the evolution of the output Jones vector in the neighbourhood of $\omega_0$ . + +The PDV can be related to the PSP, $\vec{p}$ , and DGD, $\Delta\tau$ , as well as the rotation vector and angle as: + +$$\vec{\Omega} = 2 \frac{d\gamma_T}{d\omega} \vec{y} + \sin 2\gamma_T \frac{d\vec{y}}{d\omega} + 2 \sin^2 \gamma_T \left( \vec{y} \times \frac{d\vec{y}}{d\omega} \right) = \Delta\tau \vec{p} \quad (3-15)$$ + +Equation 3-14 can be written as: + +$$\frac{d\vec{j}(\omega)}{d\omega}\bigg|_{\omega_0} = \frac{dT(\omega)}{d\omega}\bigg|_{\omega_0} T^T(\omega_0)\vec{j}(\omega_0) = -\frac{i}{2} \Delta\tau V_p \begin{bmatrix} 1 & 0 \\ 0 & -1 \end{bmatrix} V_p^T \vec{j}(\omega_0) \quad (3-16)$$ + +where: + +$$V_p = \begin{bmatrix} \cos \theta_p \exp(-i\mu_p/2) & -\sin \theta_p \exp(-i\mu_p/2) \\ \sin \theta_p \exp(i\mu_p/2) & \cos \theta_p \exp(i\mu_p/2) \end{bmatrix}$$ + +$V_p^*$ is the transpose conjugate of $V_p$ + +$$\text{and the PSP is } \vec{p} = \begin{bmatrix} \cos 2\theta_p \\ \sin 2\theta_p \cos \mu_p \\ \sin 2\theta_p \sin \mu_p \end{bmatrix}$$ + +Assuming that the PSPs are frequency invariant (over a narrow frequency interval, $\omega_0$ and $\omega_0 + \Delta\omega$ ), Equation 3-14 has a solution in the neighbourhood of $\omega_0$ : + +$$\hat{j}(\varpi) = V_p \begin{bmatrix} \exp[-i\varpi\Delta\tau/2] & 0 \\ 0 & \exp[i\varpi\Delta\tau/2] \end{bmatrix} V_p^T \vec{j}(\omega_0) = J(\varpi)\vec{j}(\omega_0) \quad (3-17)$$ + +where $\varpi$ is the deviation from $\omega_0$ . + +In the Stokes notation, Equation 3-17 corresponds to a rotation of $\varpi\Delta\tau$ about the PSP on the Poincaré sphere (PS). + +Equation 3-17 is written as a singular value decomposition. The diagonal elements of the central matrix are the eigenvalues. The columns of the matrix, $V_p$ , are the eigenvectors, which are in the Jones vector form. The first column converts to the PSP in the same form as in Equation 3-5. Call this $\vec{j}_p$ . This matrix can also be expressed in the form of Equation 3-12, with $\varpi\Delta\tau/2$ replacing $\gamma_T$ and with the elements of the PSP replacing the elements of the rotation vector. + +A change of coordinates can be applied to Equation 3-17 so the PSP matrix in the new coordinate system is the identity matrix. The $x$ and $y$ elements of the result can be convolved with the frequency domain field of a monochromatic source which can then be expressed in the time domain as a power + +function. For example, a Gaussian temporal pulse with RMS width equal to $\sigma$ , in picoseconds, and a fibre with chromatic dispersion, $D$ , in picoseconds per nanometre). The resultant output power function is a split pulse, $P(t)$ : + +$$P(t) = \frac{1}{S\sqrt{2\pi}} \left\{ \exp \left[ -\frac{(t - (\tau_G - \Delta\tau/2))^2}{2S^2} \right] u + \exp \left[ -\frac{(t - (\tau_G + \Delta\tau/2))^2}{2S^2} \right] (1-u) \right\} \quad (3-18)$$ + +where $\tau_G$ is the group delay for $u = 0.5$ + +$$S^2 = \sigma^2 + \left( \frac{\tau'}{2\sigma} \right)^2 \text{ and } \tau' = -D \frac{\lambda_0}{\omega_0}$$ + +$$u = [\vec{j}_p \times T(\omega_0) \vec{j}_0] \times [\vec{j}_p \times T(\omega_0) \vec{j}_0] \text{ in the original coordinates.}$$ + +The difference between pulse centre for $u = 0$ is $\Delta\tau$ away from the pulse centre for $u = 1$ . This is the meaning of DGD. These values of $u$ are achieved when the output Jones vector is aligned with $\vec{j}_p$ or its orthogonal counterpart, the other eigenvector. + +The RMS width of this pulse is: + +$$\text{RMS}_p = [S^2 + \Delta\tau^2 u(1-u)]^{1/2} \quad (3-19)$$ + +In measurements using the RTM Jones matrix eigenanalysis (JME), estimates of the $T$ matrix are calculated for $\omega_0$ and $\omega_0 + \Delta\omega$ , a frequency slightly larger. The frequency transfer matrix is approximated as: + +$$J(\Delta\omega) = T(\omega_0 + \Delta\omega)T^{-1}(\omega_0) \quad (3-20)$$ + +It is clear from Equation 3-17 that the argument of the ratio of eigenvalues, divided by $\Delta\omega$ , is the DGD. + +The term "first order" was originally associated with the first-order Taylor expansion associated with Equation 3-14. It could also be associated with the fact that it provides a continuous phase-linear map from the Jones vector at one frequency to the next higher frequency. + +Second order PMD could be thought of as a description of $J(\varpi)$ that provides a continuous mapping to both the frequency above and the frequency below. This can be done by replacing $\varpi\Delta\tau/2$ by a more general expression, $\gamma(\varpi)$ , that is described as a Taylor expansion: + +$$\gamma(\varpi) = \varpi\gamma_{\varpi} + \varpi^2\gamma'_{\varpi}/2 \quad (3-21)$$ + +Similarly, the angular parameters of the PSP can be written as: + +$$\theta_p(\varpi) = \theta_{p0} + \varpi\theta_{p\varpi} \quad \text{and} \quad \mu_p(\varpi) = \mu_{p0} + \varpi\mu_{p\varpi} \quad (3-22)$$ + +The use of formulae such as Equation 3-20 for the reverse frequency, the singular value decomposition of Equation 3-17, and some algebra/trigonometry can yield estimates of the parameters of Equations 3-21 and 3-22 from measured data. + +The second order PDV, $\bar{\Omega}_{\omega}$ , is defined as the frequency derivative of the PDV: + +$$\bar{\Omega}_{\omega} = \frac{d\bar{\Omega}}{d\omega} = \frac{d\Delta\tau}{d\omega} \bar{p} + \Delta\tau \frac{d\bar{p}}{d\omega} \quad (3-23)$$ + +When random mode coupling is present, the magnitude of this vector and its expected value are related to the PMD value as: + +$$\langle \bar{\Omega}_\omega \cdot \bar{\Omega}_\omega \rangle = \left\langle \left( \frac{d\Delta\tau}{d\omega} \right)^2 \right\rangle + \left\langle \Delta\tau^2 \frac{d\bar{p}}{d\omega} \cdot \frac{d\bar{p}}{d\omega} \right\rangle = \frac{1}{3} \langle \Delta\tau^2 \rangle^2 \quad (3-24)$$ + +The ratio of the first term, involving the derivative of the DGD, to the second term, involving the derivative of the PSP, is 1/8. The first term is interactive with chromatic dispersion and the second term has a depolarizing effect. + +The convolution of the expanded representation of the frequency transfer matrix with the input pulse is beyond the scope of this clause, but it is clear that the results will not be as easy to represent and will depend on the details of the parameters at the frequency of the source. If, however, one is interested in the expected values, Equation 3-24 makes it clear that these values can be calculated from the PMDRMS value and those explicit measurements are not needed. + +**3.1.7 PMDQ:** For a concatenated link comprised of $M$ individual cable sections, the PMD link design value, PMDQ, is defined as the value that the link PMD coefficient, $X_M$ , exceeds with probability $Q$ : + +$$P(X_M > \text{PMD}_Q) = Q \quad (3-25)$$ + +PMDQ is a parameter that represents a statistical extreme of the distribution of PMD values that result from a concatenation of $M$ randomly selected sections with individual PMD coefficient values. The link PMD coefficient calculation is performed using the quadrature average formula. The statistical extreme is given at a confidence level defined as $1 - Q$ , with $Q$ being small. If $Q = 10^{-4}$ , there is 99.99% confidence that the actual PMD coefficient of $M$ concatenated cables will be less than or equal to PMDQ. + +## 3.2 Types of test methods + +**3.2.1 reference test method (RTM):** A test method in which a characteristic of a specified class of optical fibres or optical fibre cables is measured strictly according to the definition of this characteristic and which gives results which are accurate, reproducible and relatable to practical use. + +**3.2.2 alternative test method (ATM):** A test method in which a given characteristic of a specified class of optical fibres or optical fibre cables is measured in a manner consistent with the definition of this characteristic and which gives results which are reproducible and relatable to the reference test method and to practical use. + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|--------------------------------------| +| a.c. | alternating current | +| ASE | Amplified Spontaneous Emission | +| ATM | Alternative Test Method | +| DGD | Differential Group Delay | +| d.c. | direct current | +| DoP | Degree of Polarization | +| DSF | Dispersion-shifted Single-mode Fibre | +| EDFA | Erbium-Doped Fibre Amplifier | +| FCFT | Fast Cosine Fourier Transform | + +| | | +|------------------|-----------------------------------------------------| +| FFP | Far-Field Pattern | +| FFS | Far-Field Scan | +| FUT | Fibre Under Test | +| FWHM | Full Width at Half Maximum | +| GINTY | General analysis for the interferometric method | +| JME | Jones Matrix Eigenanalysis | +| LED | Light Emitting Diode | +| MFD | Mode Field Diameter | +| NFP | Near-Field Pattern | +| NFS | Near-Field Scan | +| OPGW | OPtical Ground Wire | +| PMD | Polarization Mode Dispersion | +| PMD Q | Statistical parameter for link PMD | +| PMF | Polarization-Maintaining Fibre | +| PS | Poincaré Sphere | +| PSA | Poincaré Sphere Analysis | +| PSP | Principal State of Polarization | +| RMS | Root Mean Square | +| RTM | Reference Test Method | +| SBS | Stimulated Brillouin Scattering | +| SMF | Single-Mode Fibre | +| SNR | Signal-to-Noise Ratio | +| SOP | State Of Polarization | +| TINTY | Traditional analysis for the interferometric method | +| VA | Variable Aperture | +| VOA | Variable Optical Attenuator | +| WDM | Wavelength Division Multiplexing | + +## 5 Conventions + +I/O-SOP State of polarization of an input polarizer setting and an orthogonal pair of analyser settings. + +## 6 Test methods + +Both reference test method (RTM) and alternative test methods (ATMs) are usually given here for each parameter and it is the intention that both the RTM and the ATM(s) may be suitable for normal product acceptance purposes. However, when using an ATM, should any discrepancy arise, it is recommended that the RTM be employed as the technique for providing the definitive measurement results. + +NOTE – The apparatus and procedure given cover only the essential basic features of the test methods. It is assumed that the detailed instrumentation will incorporate all necessary measures to ensure stability, noise elimination, signal-to-noise ratio (SNR), etc. + +## 6.1 Test methods for polarization mode dispersion + +All the test methods report the PMD value. The conversion to PMD coefficient shall be done according to the definitions in clause 3.1.5. All procedures are restricted to wavelengths greater than or equal to that at which the fibre is effectively single mode. + +#### 6.1.1 Reference test method: The Stokes parameter evaluation technique + +##### 6.1.1.1 General + +This test method describes a procedure for measuring the PMD of single-mode optical fibres. The change in the output state of polarization (SOP) with wavelength is determined. This change can be characterized through Jones matrix eigenanalysis (JME), or the rotation of the SOP vector on the Poincaré sphere (PS). It can be applied to both short and long fibres, regardless of the degree of polarization (DoP) mode coupling. Under some circumstances, repeated measurements may be necessary to achieve satisfactory precision. + +When measuring fibres in motion [e.g., fibres in optical ground wire (OPGW)], the interferometer method could be a better choice for the dispute resolution function of the RTM. + +#### 6.1.1.2 Test apparatus + +See Figure 1 for a schematic diagram of the key components in a typical measurement system. + +![Schematic diagram of equipment (typical) for polarization mode dispersion measurement. The diagram shows a 'Tunable source' connected to a 'Polarization adjuster' (represented by two circles). The output of the adjuster passes through a series of optical components: a lens, a set of three 'Linear polarizers' labeled '0° 45° 90°', another lens, and a 'Test fibre' (represented by a circle). The output of the test fibre is then connected to a 'Polarimeter'. The diagram is labeled 'G.650.2(07)_F01'.](a7c51c18111139f9aca2805114108565_img.jpg) + +Schematic diagram of equipment (typical) for polarization mode dispersion measurement. The diagram shows a 'Tunable source' connected to a 'Polarization adjuster' (represented by two circles). The output of the adjuster passes through a series of optical components: a lens, a set of three 'Linear polarizers' labeled '0° 45° 90°', another lens, and a 'Test fibre' (represented by a circle). The output of the test fibre is then connected to a 'Polarimeter'. The diagram is labeled 'G.650.2(07)\_F01'. + +Figure 1 – Schematic diagram of equipment (typical) + +##### 6.1.1.2.1 Light source + +Use a single-line laser or narrow-band source that is tunable across the intended measurement wavelength range. The spectral distribution shall be narrow enough so that the light emerging from the test fibre remains polarized under all conditions of the measurement. A DoP of 90% or greater is preferred, although measurements may be performed with values as low as 25% with reduced precision. For a given DGD, $\Delta\tau$ , the lowest DoP which can result is given by: + +$$DoP = 100 \exp \left[ -\frac{1}{4 \ln 2} \left( \frac{\pi c \Delta\tau \Delta\lambda_{FWHM}}{\lambda_0^2} \right)^2 \right] \quad (6-1)$$ + +assuming a Gaussian spectrum of width $\Delta\lambda_{FWHM}$ , where FWHM denotes full width at half maximum, centred at $\lambda_0$ . DoP is expressed as a percentage. + +##### **6.1.1.2.2 Polarization adjuster** + +A polarization adjuster follows the laser and is set to provide roughly circularly polarized light to the polarizers, so that the polarizers never cross polarization with their input light. Adjust polarization as follows. Set the tunable laser wavelength to the centre of the range to be measured. Insert each of the three polarizers into the beam and perform three corresponding power measurements at the output of the polarizers. Adjust the source polarization via the polarization adjuster such that the three powers fall within approximately a 3 dB range of one another. In an open beam version of the set-up, a waveplate may perform the polarization adjustment. + +##### **6.1.1.2.3 Polarizers** + +Three linear polarizers at relative angles of approximately $45^\circ$ are arranged to be inserted into the light beam in turn. The actual relative angles shall be known. + +##### **6.1.1.2.4 Input optics** + +An optical lens system or single-mode fibre (SMF) pigtail may be employed to excite the test fibre. + +##### **6.1.1.2.5 Fibre pigtail** + +If pigtails are used, interference effects due to reflections should be avoided. This may require index-matching materials or angled cleaves. The pigtails shall be single mode. + +##### **6.1.1.2.6 Optical lens system** + +If an optical lens system is used, some suitable means, such as a vacuum chuck, shall be used to stably support the input end of the fibre. + +##### **6.1.1.2.7 Cladding mode stripper** + +Remove any cladding mode power from the test fibre. Under most circumstances, the fibre coating will perform this function; otherwise, employ a device that extracts cladding mode power. + +##### **6.1.1.2.8 Output optics** + +Couple all power emitted from the test fibre to the polarimeter. An optical lens system, a butt splice to an SMF pigtail or an index-matched coupling made directly to the detector system are examples of means that may be used. + +##### **6.1.1.2.9 Polarimeter** + +Use a polarimeter to measure the three output states of polarization corresponding to insertion of each of the three polarizers. The wavelength range of the polarimeter shall include the wavelengths produced by the light source. + +#### **6.1.1.3 Measurement procedure** + +The test sample shall be a known length of a single-mode optical fibre which may or may not be cabled. The sample and pigtails shall be fixed in position at a nominally constant temperature throughout the measurement. Temperature stability of the test device may be observed by viewing the output state of polarization of the test fibre on a PS display. In a time period corresponding to an adjacent pair of Jones matrix measurements, output polarization change should be small relative to the change produced by a wavelength increment. + +NOTE – Although the test sample is normally a fibre, this test can also be performed on discrete components. In this case, PMD coefficient is not relevant. + +It is important to minimize deployment-induced mode coupling when measuring uncabled fibres, which is done in order to support the primary requirements of cabled fibre $PMD_Q$ . In this case, the fibre shall be supported in some manner (usually on a reel having a minimum wind radius of 150 mm), with essentially zero fibre tension (typically less than 5 g force), and no tensioned crossovers. These + +deployment requirements can limit the length that can be measured, depending on the spool diameter, and can make the measurement a destructive one. Multi-layer windings are possible, but should be qualified by comparison with single-layer results on shorter lengths. + +The measurement of uncabled fibre deployed on shipping spools is not recommended. PMD results with this deployment have been shown to be substantially less than what would be obtained in cable form for high PMD fibre and substantially greater than what would be obtained in cable form for low PMD fibre. + +Couple the light source through the polarization adjuster to the polarizers. + +Couple the output of the polarizers to the input of the fibre under test. + +Couple the output of the fibre under test to the input of the polarimeter. + +Select the wavelength interval, $\Delta\lambda$ , over which the measurements are to be performed. The maximum allowable value of $\Delta\lambda$ (around $\lambda_0$ ) is set by the requirement: + +$$\Delta\tau_{\max} \Delta\lambda \leq \frac{\lambda_0^2}{2c} \quad (6-2)$$ + +where $\Delta\tau_{\max}$ is the maximum expected DGD within the measurement wavelength range. For example, the product of maximum DGD and wavelength interval shall remain less than 4 ps nm at 1 550 nm and less than 2.8 ps nm at 1 300 nm. This requirement ensures that from one test wavelength to the next, the output state of polarization rotates less than $180^\circ$ about the principal states axis of the PS. If a rough estimate of $\Delta\tau_{\max}$ cannot be made, perform a series of sample measurements across the wavelength range, each measurement using a closely spaced pair of wavelengths appropriate to the spectral width and minimum tuning step of the optical source. Multiply the maximum DGD measured in this way by a safety factor of three, substitute this value for $\Delta\tau_{\max}$ in Expression 6-2 and compute the value of $\Delta\lambda$ to be used in the actual measurement. If there is concern that the wavelength interval used for a measurement was too large, the measurement may be repeated with a smaller wavelength interval. If the shape of the curve of DGD vs wavelength and the mean DGD are essentially unchanged, the original wavelength interval was satisfactory. + +Gather the measurement data. At the selected wavelengths, insert each of the polarizers and record corresponding Stokes parameters from the polarimeter. + +#### 6.1.1.4 Calculations or interpretation of result + +There are two ways [JME and PS analysis (PSA)] of analysing the Stokes parameters that were measured in clause 6.1.1.3. Both analysis methods deduce the rotation of the output Stokes vectors at one optical frequency to the next frequency. The DGD is proportional to the rotation angle and inversely proportional to the frequency difference. The two methods are mathematically equivalent for first-order PMD for negligible PDL. + +The Stokes parameters for a given wavelength are the normalized Stokes output vectors which are represented as $\vec{H}$ , $\vec{Q}$ and $\vec{V}$ for relative input linear SOP angles of $0^\circ$ , $45^\circ$ and $90^\circ$ , respectively. + +In clause 6.1.3, wavelength is used to describe the measurement. Angular optical frequency, $\omega = 2\pi c/\lambda$ (THz), is the most useful metric for the calculations. The calculations below are given for a single pair of adjacent frequencies designated as $\omega_0$ and $\omega_0 + \Delta\omega$ . This pair yields a DGD value. The DGD values are calculated for each ascending pair of frequencies over a frequency range using the same calculations. + +The average of all the DGD values is reported as the PMD value. + +##### 6.1.1.4.1 Jones matrix eigenanalysis + +For a given frequency, use Equation 3-5 to convert the measured unit output Stokes vectors to Jones vectors by assuming that $0 \leq \theta \leq \pi$ . The complex $x$ and $y$ elements of these vectors are designated as: $h_x$ , $h_y$ , $q_x$ , $q_y$ , $v_x$ , and $v_y$ . Using these, calculate the following ratios: + +$$k_1 = h_x / h_y \quad k_2 = v_x / v_y \quad k_3 = q_x / q_y \quad k_4 = \frac{k_3 - k_2}{k_1 - k_3} \quad (6-3)$$ + +The assumption of $0 \leq \theta \leq \pi$ is not relevant because of the ratio calculations. + +For the frequency, the Jones transfer matrix, $T$ , is calculated as: + +$$T = \begin{bmatrix} k_1 k_4 & k_2 \\ k_4 & 1 \end{bmatrix} \quad (6-4)$$ + +The actual transfer matrix is the matrix of Equation 6-4 times an unknown complex constant that is inversely proportional to the square root of the determinant of the calculated matrix. This constant is not needed for the rest of the calculations, however. + +For a pair of frequencies, the Jones frequency transfer matrix, $J$ , is calculated as: + +$$J(\omega_0) = T(\omega_0 + \Delta\omega)T^{-1}(\omega_0) \quad (6-5)$$ + +Calculate the two eigenvalues, $\rho_1(\omega_0)$ and $\rho_2(\omega_0)$ of $J(\omega_0)$ . The DGD, $\Delta\tau(\omega_0)$ is given as: + +$$\Delta\tau(\omega_0) = \frac{|\arg(\rho_1(\omega_0)/\rho_2(\omega_0))|}{\Delta\omega} \quad (6-6)$$ + +where: + +$$\arg(me^{j\theta}) = \theta \quad \text{with } m \text{ and } \theta \text{ both real, and } |\theta| < \pi.$$ + +The data may be displayed as a function of wavelength as shown in Figure 2 or as a histogram as in Figure 3. + +![Figure 2: DGD data vs frequency. A line graph showing multiple curves of DGD (ps) versus Frequency (THz). The x-axis ranges from 190 to 205 THz, and the y-axis ranges from 0 to 0.25 ps. The curves show varying trends, with some increasing and others decreasing as frequency increases. The label G.650.2(07)_F02 is present in the bottom right corner of the plot area.](d74e83c626faf36154df84683d6c6673_img.jpg) + +Figure 2: DGD data vs frequency. A line graph showing multiple curves of DGD (ps) versus Frequency (THz). The x-axis ranges from 190 to 205 THz, and the y-axis ranges from 0 to 0.25 ps. The curves show varying trends, with some increasing and others decreasing as frequency increases. The label G.650.2(07)\_F02 is present in the bottom right corner of the plot area. + +**Figure 2 – DGD data vs frequency** + +![Figure 3 – DGD data as a histogram. The x-axis is labeled 'DGD (ps)' and ranges from 0 to 0.24 with major ticks every 0.02. The y-axis is labeled 'Frequency' and ranges from 0 to 60 with major ticks every 10. The histogram shows a distribution of DGD values, with a peak frequency of approximately 48 at a DGD of about 0.05 ps. The distribution is skewed to the right, with most values between 0.02 and 0.14 ps, and a few outliers up to 0.24 ps. A small label 'G.650.2(07)_F03' is visible in the bottom right corner of the plot area.](b2d16e07bfa79d67a8adabf7e26c7764_img.jpg) + +Figure 3 – DGD data as a histogram. The x-axis is labeled 'DGD (ps)' and ranges from 0 to 0.24 with major ticks every 0.02. The y-axis is labeled 'Frequency' and ranges from 0 to 60 with major ticks every 10. The histogram shows a distribution of DGD values, with a peak frequency of approximately 48 at a DGD of about 0.05 ps. The distribution is skewed to the right, with most values between 0.02 and 0.14 ps, and a few outliers up to 0.24 ps. A small label 'G.650.2(07)\_F03' is visible in the bottom right corner of the plot area. + +**Figure 3 – DGD data as a histogram** + +##### 6.1.1.4.2 Poincaré sphere analysis (PSA) + +The analysis is based on an arcsine function to determine the rotation of the normalized Stokes vectors on the PS. + +From the measured normalized Stokes vectors, $\vec{H}$ , $\vec{V}$ and $\vec{Q}$ , compute: + +$$\vec{h} = \vec{H}, \quad \vec{q} = \frac{\vec{H} \times \vec{Q}}{|\vec{H} \times \vec{Q}|} \times \vec{H}, \quad \vec{v} = \frac{\vec{q} \times \vec{V}}{|\vec{q} \times \vec{V}|} \times \vec{q} \quad (6-7)$$ + +This makes the analysis independent of the input SOPs, consequently there is no need to know their values. + +From the Stokes vectors, $\vec{h}$ , $\vec{v}$ and $\vec{q}$ , form the vector products $\vec{c} = \vec{h} \times \vec{q}$ and $\vec{c}' = \vec{q} \times \vec{v}$ at each wavelength. For each frequency increment, compute the finite differences, + +$$\begin{aligned} \Delta \vec{h} &= \vec{h}(\omega_0 + \Delta\omega) - \vec{h}(\omega_0) & \Delta \vec{q} &= \vec{q}(\omega_0 + \Delta\omega) - \vec{q}(\omega_0) & \Delta \vec{v} &= \vec{v}(\omega_0 + \Delta\omega) - \vec{v}(\omega_0) \\ \Delta \vec{c} &= \vec{c}(\omega_0 + \Delta\omega) - \vec{c}(\omega_0) & \Delta \vec{c}' &= \vec{c}'(\omega_0 + \Delta\omega) - \vec{c}'(\omega_0) \end{aligned} \quad (6-8)$$ + +Find the DGD, $\Delta\tau$ , for a particular frequency increment from Equation 6-9: + +$$\Delta\tau = \frac{1}{\Delta\omega} \cdot \left[ \arcsin \left( \frac{1}{2} \sqrt{\frac{1}{2} (\Delta \vec{h}^2 + \Delta \vec{q}^2 + \Delta \vec{c}^2)} \right) + \arcsin \left( \frac{1}{2} \sqrt{\frac{1}{2} (\Delta \vec{q}^2 + \Delta \vec{v}^2 + \Delta \vec{c}'^2)} \right) \right] \quad (6-9)$$ + +NOTE – $\Delta \vec{h}^2 = \Delta \vec{h} \cdot \Delta \vec{h}$ . + +#### 6.1.1.5 Presentation of the results + +The following details shall be presented: + +- Identification of the sample measured. +- Test length. +- The wavelength range over which the measurement was performed, the wavelength step size, and the number of sampled points. +- The physical configuration of the fibre or cable sample. +- Mode-coupling type (negligible, semi-random or random). +- Method of analysis (JME or PS). + +- g) PMD in picoseconds. If the degree of mode coupling is known, the PMD coefficient may be given in picoseconds per kilometre (negligible mode coupling) or picoseconds per root kilometre (random mode coupling). +- h) When an average PMD has been determined from repeated measurements of the sample, record the number of measurements performed. + +### **6.1.2 First alternative test method: State of polarization (SOP) method** + +This method has been shown to be incomplete and has therefore been removed. Consequently, the method is only fundamentally valid in negligible mode coupling, but it is not valid in random mode coupling. For more information pertaining to PMD theory, see [b-IEC/TR 61282-9]. + +### **6.1.3 Second alternative test method: Interferometric method** + +#### **6.1.3.1 General** + +This test method describes a procedure for measuring the PMD of single-mode optical fibres and cables. + +The measured value represents $PMD_{RMS}$ over a broad measurement wavelength range of typical broadband sources, such as a light-emitting diode (LED), combination of super LEDs or amplified spontaneous emission (ASE) source in the 1 310 nm or the 1 550 nm window or any other window of interest, depending on user requirements. + +The PMD is determined from an interferogram containing the autocorrelation and cross-correlation function of the emerging electromagnetic field at one end of the fibre under test (FUT) when illuminated by the broadband polarized source at the other end. + +The main advantage of this method is that the measurement time is very fast and the equipment can be easily used in the field. The dynamics and stability are provided by the well-established Fourier transform spectroscopy technique. + +The fibre shall be single mode in the measured wavelength range. + +The INTY method uses two analyses that entail slightly different measurements: + +- Traditional analysis for the interferometric method (TINTY) using a set of specific operating conditions for its successful applications and a basic set-up. +- General analysis for the interferometric method (GINTY) using no limiting operating conditions, but using a modified set-up compared to TINTY. + +#### **6.1.3.2 Test apparatus** + +A generic set-up is shown in Figure 4, which is the basis of INTY experimental implementation. Variations of this set-up are possible and are shown below. The interferometer can be an air path type or a fibre type, it can be of the Michelson or Mach–Zehnder type and it can be located at the source or at the detector end. Examples are given in Figures 5, 6 and 7. + +NOTE – When a fibre-type interferometer is used, care should be given to the fibre chromatic dispersion that may add to the measurement uncertainties. + +![Figure 4: Generic set-up for the interferometric technique. The diagram shows a broadband source connected to a polarizer, which outputs S_s(v) and Stokes vector s_0. This is followed by a link with Jones matrix J(v) and SOP block, outputting S_o(v) and Stokes vector s(v). The signal then passes through an analyser with transmission axis s_a, outputting S(v). This signal is then split into an interferometer, which outputs fringes P-tilde(tau). The fringes are processed to show cross-correlation and auto-correlation envelopes. A graph on the left shows the Spectrum S(v) vs Optical frequency (v), with a curve labeled S_o(v). A graph on the right shows the Fringes vs Delay (tau), with a curve labeled auto-correlation and a smaller curve labeled cross-correlation. A box in the middle contains the equation S(v) = 1/2 {1 + [s(v) · s_a]} S_o(v). Arrows indicate the flow of data and processing steps, including Fourier transform and modulus of sum.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +Figure 4: Generic set-up for the interferometric technique. The diagram shows a broadband source connected to a polarizer, which outputs S\_s(v) and Stokes vector s\_0. This is followed by a link with Jones matrix J(v) and SOP block, outputting S\_o(v) and Stokes vector s(v). The signal then passes through an analyser with transmission axis s\_a, outputting S(v). This signal is then split into an interferometer, which outputs fringes P-tilde(tau). The fringes are processed to show cross-correlation and auto-correlation envelopes. A graph on the left shows the Spectrum S(v) vs Optical frequency (v), with a curve labeled S\_o(v). A graph on the right shows the Fringes vs Delay (tau), with a curve labeled auto-correlation and a smaller curve labeled cross-correlation. A box in the middle contains the equation S(v) = 1/2 {1 + [s(v) · s\_a]} S\_o(v). Arrows indicate the flow of data and processing steps, including Fourier transform and modulus of sum. + +**Figure 4 – Generic set-up for the interferometric technique** + +Parameters used in Figure 4 and throughout this Recommendation: + +- $\nu$ optical frequency ( $\lambda\nu = c$ ) +- $\tau$ difference of round-trip delay between the two arms of the interferometer +- $S_s(\nu)$ optical spectrum, at FUT input $\equiv$ spectral density of $\vec{E}_s(\nu)$ the source electric field spectrum +- $S_o(\nu)$ optical spectrum, at FUT output (analyser input) +- $S(\nu)$ optical spectrum, at analyser output (interferometer input) +- $\vec{s}_0$ input SOP (at FUT input; a unit Stokes vector) +- $\vec{s}(\nu)$ output SOP (at FUT output) +- $\vec{s}_a$ analyser transmission axis +- $\vec{s}(\nu) \cdot \vec{s}_a$ Stokes parameter giving the projection of $\vec{s}(\nu)$ on the analyser transmission axis. It is this parameter that contains the PMD information +- $P(\tau)$ optical power at the interferometer output, as a function of delay $\tau$ +- $\tilde{P}(\tau)$ $\tau$ -dependent part of $P(\tau)$ [alternating current (a.c.) part] +- $P_0$ constant part of $P(\tau)$ [direct current (d.c.) parts] +- $E(\tau)$ fringe envelope +- $E_x(\tau)$ cross-correlation envelope +- $E_0(\tau)$ autocorrelation envelope + +The optical power at the interferometer output, $P(\tau)$ , is equal to the sum of a.c. and d.c. parts. Both parts are equal at $\tau = 0$ so the a.c. part can be calculated. For an ideal interferometer, the a.c. part is an even function, the right half of which is equal to the cosine Fourier transform of the optical + +spectrum, $S(\nu)$ , emitted from the analyser. For non-ideal interferometers, some corrections may be applied, depending on the details of the implementation. + +For TINTY, the envelope of the interferogram, $E(\tau)$ , is the absolute value of the a.c. part. For GINTY, additional calculations to obtain the cross-correlation and autocorrelation envelopes are described in clause 6.1.3.4.2. These calculations involve two measured interferograms resulting from the analyser being set at two orthogonal SOPs. + +Other set-ups are shown in Figures 5, 6 and 7. + +![Figure 5: Two diagrams (a and b) showing the interferometric method using a Michelson interferometer. Diagram (a) uses a bulk optic beam splitter, while diagram (b) uses a fibre coupler. Both setups include an optical source, polarizer, fibre under test, connector or splice, fixed mirror, moving mirror, fringe envelope detection, and a controller.](e180f2b5fcbe8001554a7c0677cd3f82_img.jpg) + +The diagram illustrates two configurations for a Michelson interferometer setup. Both start with an 'Optical source' connected to a 'Polarizer'. The polarized light enters a 'Fibre under test' through a 'Connector or splice'. In configuration (a), the fibre output connects to a 'Bulk optic beam splitter'. One output path leads to a 'Fixed mirror', and the other to a 'Moving mirror'. The reflected light is recombined at the beam splitter and sent to 'Fringe envelope detection', which is controlled by a 'Controller'. In configuration (b), the fibre output connects to a 'Coupler'. One output path leads to a 'Fixed mirror', and the other to a 'Moving mirror'. The reflected light is recombined at the coupler and sent to 'Fringe envelope detection', which is controlled by a 'Controller'. A label 'G.650.2(15)\_F05' is present in the bottom right of diagram (b). + +**a) With bulk optic beam splitter** + +**b) With fibre coupler** + +G.650.2(15)\_F05 + +Figure 5: Two diagrams (a and b) showing the interferometric method using a Michelson interferometer. Diagram (a) uses a bulk optic beam splitter, while diagram (b) uses a fibre coupler. Both setups include an optical source, polarizer, fibre under test, connector or splice, fixed mirror, moving mirror, fringe envelope detection, and a controller. + +**Figure 5 – The interferometric method using a Michelson interferometer** + +![Figure 6: Schematic diagram of a Mach-Zehnder type interferometer with an air path. The setup starts with an LED source followed by a polarizer and a λ/2 waveplate. The light enters a beam splitter. One output path goes to a mirror. The other output path passes through another beam splitter, then a λ/2 waveplate, and then a mirror. Both reflected paths recombine at the second beam splitter. The combined path then passes through a movable corner cube, which is controlled by a computer via a delay line. The light then passes through a polarizer and enters a fringe envelope detection unit. A fibre is shown in the lower path, connected by a connector or splice. The diagram is labeled G.650.2(15)_F06.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +Figure 6: Schematic diagram of a Mach-Zehnder type interferometer with an air path. The setup starts with an LED source followed by a polarizer and a λ/2 waveplate. The light enters a beam splitter. One output path goes to a mirror. The other output path passes through another beam splitter, then a λ/2 waveplate, and then a mirror. Both reflected paths recombine at the second beam splitter. The combined path then passes through a movable corner cube, which is controlled by a computer via a delay line. The light then passes through a polarizer and enters a fringe envelope detection unit. A fibre is shown in the lower path, connected by a connector or splice. The diagram is labeled G.650.2(15)\_F06. + +**Figure 6 – The interferometric method using a Mach–Zehnder type interferometer with an air path** + +![Figure 7: Schematic diagram of the GINTY using I/O-SOP scrambling and a polarization diversity detector. A broadband source is followed by a polarizer. The light then passes through a link, which is affected by SOP scramblers. The output of the link is analyzed by an analyzer and an interferometer. The interferometer output is then processed by a polarization diversity detector, which consists of a polarization beam splitter and two detectors. The output of the detectors is labeled as Fringes: P̃x(τ) and P̃y(τ). The diagram is labeled G.650.2(15)_F07.](d734a6ea1b381280f043fcf70391b6db_img.jpg) + +Figure 7: Schematic diagram of the GINTY using I/O-SOP scrambling and a polarization diversity detector. A broadband source is followed by a polarizer. The light then passes through a link, which is affected by SOP scramblers. The output of the link is analyzed by an analyzer and an interferometer. The interferometer output is then processed by a polarization diversity detector, which consists of a polarization beam splitter and two detectors. The output of the detectors is labeled as Fringes: P̃x(τ) and P̃y(τ). The diagram is labeled G.650.2(15)\_F07. + +**Figure 7 – The GINTY using I/O-SOP scrambling and a polarization diversity detector** + +##### 6.1.3.2.1 Optical source + +A polarized broad spectrum source, such as an LED, set of super LEDs or ASE source followed by a polarizer, shall be used. The centre wavelength of the light source shall be within the O-band or the C-band, or within any band of interest. A typical value of the source linewidth is about 60 nm or larger FWHM. TINTY requires that the spectral shape of the source shall be approximately Gaussian, without ripples which could influence the autocorrelation function of the emerging light. GINTY does not impose any such requirements. The source linewidth (also called spectral width in the LED field), $\Delta\lambda$ , must be known to calculate the coherence time, $t_c$ , which is determined using Equation 6-10: + +$$t_c = \frac{\lambda_0^2}{\Delta\lambda c} \quad (6-10)$$ + +where: + +$\lambda_0$ is the source centre wavelength + +$\Delta\lambda$ is the source linewidth + +$c$ is the speed of light in a vacuum + +##### 6.1.3.2.2 Analyser + +The analyser shall polarize the light over the full wavelength range of the source. For GINTY, the analyser must be capable of being rotated to a setting orthogonal to the initial setting. + +##### 6.1.3.2.3 Polarization scramblers (optional) + +In Figure 7, the polarization scrambler allows the selection of any SOPs for the FUT input and output. The polarization beamsplitter allows simultaneous detection of what would be detected by two orthogonal analyser settings. The functionality of the polarization scrambler selecting various SOPs for the input and various analyser settings at the output can be achieved by other means. + +##### 6.1.3.2.4 Interferometer beamsplitter + +The beamsplitter of the interferometer is used to split the incident polarized light into two components propagating in the interferometer's arms. The beamsplitter can be a fibre coupler as shown in Figure 5-b or a bulk optic beamsplitter as shown in Figure 5-a. + +##### 6.1.3.2.5 Detector + +The light emerging from the FUT is coupled to a photodetector whose SNR is adequate for the measurement. The detection system may include synchronous detection by chopper and lock-in amplifier or comparable techniques. + +##### 6.1.3.2.6 Computer + +For the analysis of the interference pattern, a computer with suitable software shall be used. + +#### 6.1.3.3 Samples + +The FUT sample shall be of known length of SMF that may or may not be cabled. The sample and pigtails must be fixed in position at a nominally constant temperature throughout the measurement. The standard ambient conditions shall be employed. In the case of installed fibres and cables, prevailing deployment conditions may be used. + +It is important to minimize deployment-induced mode coupling when measuring uncabled fibres, which is done in order to support the primary requirements of cabled fibre $PMD_Q$ . In this case, the fibre shall be supported in some manner (usually on a reel having a minimum wind radius of 150 mm), with essentially zero fibre tension (typically less than 0.05 N or 5 g force), and no tensioned crossovers. These deployment requirements can limit the length that can be measured, depending on the spool diameter, and can make the measurement a destructive one. Multi-layer windings are possible, but should be qualified by comparison with single-layer results on shorter lengths. + +The measurement of uncabled fibre deployed on shipping spools is not recommended. PMD results with this deployment have been shown to be substantially less than those obtained in cable form for high PMD fibre and substantially greater than those obtained in cable form for low PMD fibre. + +NOTE – Although the test sample is normally a fibre, this test can also be performed on discrete components. In this case, PMD coefficient is not relevant. However, in the case of TINTY, PMD resolution is always limited by the width of the autocorrelation peak (typically in the 100 fs range). GINTY does not suffer from such limitations and PMD resolutions limited solely by the instrument implementation uncertainties can be achieved (typically in the 10 fs range or less). + +#### 6.1.3.4 Procedure + +One end of the FUT is coupled to the polarized output of the polarized light source. The other end is coupled to the output optics. This can be done by standard fibre connectors, splices or by a fibre alignment system. If the latter is used, some index-matching oil should be used to avoid reflections. + +The optical output power of the light source is adjusted to a reference value characteristic for the detection system used. To get a sufficient fringe contrast, the optical power in both arms shall be almost identical. + +##### 6.1.3.4.1 TINTY procedure + +Make a first acquisition in moving the mirror of the interferometer arm and recording the intensity of the light. Subtract the value found for $\tau = 0$ from the interferogram to obtain $\tilde{P}(\tau)$ . The absolute value of $\tilde{P}(\tau)$ is the fringe envelope, $E(\tau)$ . + +From the fringe pattern obtained for one selected state of polarization, the PMD delay can be calculated as described below. A typical example of a fringe pattern for low and high polarization mode coupling is shown in Figure 8. + +If mode coupling is insufficient or the PMD is low, it is recommended that the measurement be repeated for different SOPs or the SOP modulated during the measurement in order to obtain a result which is an average over all SOPs. + +![Figure 8: Four plots (a, b, c, d) showing Intensity vs. PMD delay (ps). Plots (a) and (b) are for an autocorrelation type instrument, while (c) and (d) are for a cross-correlation type instrument. (a) and (c) show negligible polarization mode coupling with sharp peaks. (b) and (d) show random polarization mode coupling with broader, noisy peaks.](cb74fd9f5ec715dd3e2e325b864b48bc_img.jpg) + +Figure 8 consists of four subplots arranged in a 2x2 grid, labeled (a) through (d). Each plot shows 'Intensity' on the y-axis (ranging from 0 to 1.2) against 'PMD delay (ps)' on the x-axis. + - Subplot (a) shows a sharp peak at 0 ps and a smaller peak around 1.2 ps. The x-axis ranges from -3.0 to 3.0 ps. + - Subplot (b) shows a broad, noisy peak centered at 0 ps. The x-axis ranges from -10.0 to 10.0 ps. + - Subplot (c) shows two sharp peaks at approximately -1.5 ps and 1.5 ps, with a small peak at 0 ps. The x-axis ranges from -3.0 to 3.0 ps. + - Subplot (d) shows a broad, noisy peak centered at 0 ps. The x-axis ranges from -3.0 to 3.0 ps. + A small label 'G.650.2(15)\_F08' is located in the bottom right corner of subplot (d). + +Figure 8: Four plots (a, b, c, d) showing Intensity vs. PMD delay (ps). Plots (a) and (b) are for an autocorrelation type instrument, while (c) and (d) are for a cross-correlation type instrument. (a) and (c) show negligible polarization mode coupling with sharp peaks. (b) and (d) show random polarization mode coupling with broader, noisy peaks. + +**Figure 8 – Example of a fringe pattern obtained with the autocorrelation type instrument (a, b) and with the cross-correlation type instrument (c, d) for negligible (top) and random (bottom) polarization mode coupling** + +The fringe envelopes obtained from TINTY are a combination of the cross-correlation and autocorrelation functions. An algorithm must be used to try to separate out the part that is from the cross-correlation function. + +##### 6.1.3.4.2 GINTY procedure + +The combination of a particular input polarizer setting and an orthogonal pair of analyser settings is called an I/O-SOP. Complete the scan(s) for the two interferograms and subtract the d.c. part from each to obtain $\tilde{P}_x(\tau)$ and $\tilde{P}_y(\tau)$ , the orthogonally generated fringes. + +The cross-correlation and autocorrelation fringe envelopes, $E_x(\tau)$ and $E_0(\tau)$ are calculated as: + +$$E_x(\tau) = |\tilde{P}_x(\tau) - \tilde{P}_y(\tau)| \quad E_0(\tau) = |\tilde{P}_x(\tau) + \tilde{P}_y(\tau)| \quad (6-11)$$ + +These functions are squared for the purposes of later calculations and display. Some examples of squared cross-correlation results are shown in Figures 9, 10 and 11. Note that the autocorrelation peak seen with the TINTY is not present. + +![Figure 9: A plot showing the Mean square X-envelope versus Delay (ps). The x-axis ranges from -20 to 20 ps, and the y-axis ranges from -0.2 to 1.8. The plot displays a noisy, high-frequency signal (black line) that follows a smooth, bell-shaped envelope (dashed line). The envelope peaks at approximately 1.0 at 0 ps delay. The signal is centered around 0 ps delay. The plot is labeled G.650.2(15)_F09.](c17eaf807acd5faec68da19dd16929be_img.jpg) + +Figure 9: A plot showing the Mean square X-envelope versus Delay (ps). The x-axis ranges from -20 to 20 ps, and the y-axis ranges from -0.2 to 1.8. The plot displays a noisy, high-frequency signal (black line) that follows a smooth, bell-shaped envelope (dashed line). The envelope peaks at approximately 1.0 at 0 ps delay. The signal is centered around 0 ps delay. The plot is labeled G.650.2(15)\_F09. + +**Figure 9 – Example of a fringe pattern obtained with GINTY and I/O-SOP scrambling for random mode coupling** + +![Figure 10: A plot showing the Mean square X-envelope versus Delay (ps). The x-axis ranges from -1.4 to 1.4 ps, and the y-axis ranges from -0.2 to 1.8. The plot displays three distinct peaks. The central peak is at 0 ps delay with a height of approximately 1.0. Two side peaks are located at approximately -0.7 ps and 0.7 ps, with heights of approximately 0.9. Vertical dashed red lines mark the side peaks and are labeled -DGD and DGD. The text σ_τs = 0.0499 is present in the plot area. The plot is labeled G.650.2(15)_F10.](48a4d999034fb203698ddc187c259679_img.jpg) + +Figure 10: A plot showing the Mean square X-envelope versus Delay (ps). The x-axis ranges from -1.4 to 1.4 ps, and the y-axis ranges from -0.2 to 1.8. The plot displays three distinct peaks. The central peak is at 0 ps delay with a height of approximately 1.0. Two side peaks are located at approximately -0.7 ps and 0.7 ps, with heights of approximately 0.9. Vertical dashed red lines mark the side peaks and are labeled -DGD and DGD. The text σ\_τs = 0.0499 is present in the plot area. The plot is labeled G.650.2(15)\_F10. + +**Figure 10 – Example of a fringe pattern obtained with GINTY and I/O-SOP scrambling for negligible mode coupling** + +![Figure 11: A plot showing the Mean square X-envelope (Y-axis, ranging from -0.2 to 1.8) versus Delay (ps) (X-axis, ranging from -30 to 30). The plot displays a noisy, high-frequency signal (black line) and a smooth, low-frequency envelope (white line) that follows the general shape of the signal. The envelope peaks around 0 ps delay. The plot is labeled G.650.2(15)_F11 in the bottom right corner.](bfb6d182d624680db577069bbc0b2a93_img.jpg) + +Figure 11: A plot showing the Mean square X-envelope (Y-axis, ranging from -0.2 to 1.8) versus Delay (ps) (X-axis, ranging from -30 to 30). The plot displays a noisy, high-frequency signal (black line) and a smooth, low-frequency envelope (white line) that follows the general shape of the signal. The envelope peaks around 0 ps delay. The plot is labeled G.650.2(15)\_F11 in the bottom right corner. + +**Figure 11 – Example of a fringe pattern obtained with GINTY and I/O-SOP scrambling for mixed mode coupling** + +Options for polarization scrambling follow. When multiple I/O-SOPs are measured, distinguish them by adding a subscript $i$ , where $i = 1, 2, 3 \dots$ , for later calculations. + +###### 6.1.3.4.2.1 The nine state Mueller set + +The sum of nine squared envelopes observed with nine specific I/O-SOPs is rigorously equal to the uniformly scrambled mean squared envelope. These nine I/O-SOPs are: three analyser-axes forming a right-angled trihedron, for each three input SOPs also forming a right-angled trihedron. + +###### 6.1.3.4.2.2 Random scrambling + +**Scan-to-scan scrambling:** Automatic/manual setting of the scramblers at each scan. + +**Continuous scrambling:** When squared envelopes are summed, scrambling can be performed while scanning. Automated scramblers are set to cover the sphere continuously as a function of time. + +**Fast, single-scan scrambling:** If scramblers are sufficiently fast, well-scrambled squared envelopes can be observed in a single-scan. However, this requires special provisions to avoid crosstalk between the a.c. part and the previously d.c. part of the interferogram. + +#### 6.1.3.5 Calculations + +Both these calculations report $PMD_{RMS}$ . For ideal random mode coupling when the interferogram is of an ideal Gaussian shape, this may be converted to $PMD_{AVG}$ using Equation 3-3. + +##### 6.1.3.5.1 TINTY calculations + +For negligible mode coupling, the separation of the single well-defined peaks from the centre is the DGD value, which is also the PMD value. + +The following calculations are suitable for the random mode-coupling regime associated with long fibres/cables or links. The spread in the fringe envelope, discounting the centre peak, is characterized. The $PMD_{RMS}$ value is determined from the second moment (RMS width) of the cross-correlation function of the detected signal (fringe envelope). + +$$PMD_{RMS} = \left( \sqrt{\frac{3}{4}} \right) \sigma_{\epsilon} \quad (6-12)$$ + +where: + +$\sigma_\varepsilon$ is the RMS width of the cross-correlation envelope + +A detailed algorithm for the calculation of $\sigma_\varepsilon$ from a measured fringe envelope is described in clause I.1. + +For certain assumptions given below, Equation 6-12 can be related to Equation 3-2 as: + +$$\langle \Delta\tau^2 \rangle = \frac{3}{4} \langle \sigma_\varepsilon^2 \rangle \quad (6-13)$$ + +Equation 6-13 is obtained from the theory given the following assumptions: + +- Ideal random mode coupling. + +NOTE 1 – Ideal random coupling means $L/h \rightarrow \infty$ , and a uniformly distributed birefringence axis. $L$ is the device length and $h$ is the polarization coupling-length. For a device consisting of $N$ concatenated birefringent segments of length $h$ , this corresponds to $N \rightarrow \infty$ with uniformly distributed axes. + +NOTE 2 – Analysis of no (or negligible) mode coupling is possible. + +- A purely Gaussian source, with no ripples. + +- PMD $\gg \sigma_0$ + +where: + +$\sigma_0$ is the RMS width of the auto-correlation envelope; + +- Ergodic conditions. + +NOTE 3 – Given that the source is Gaussian, the result must be some form of weighted average of the DGD values. This weighting is not specified in TINTY, but is in GINTY. For this reason, this method is expected to give a different result for a given wavelength range and time than one of the methods that use a rectangular weighting (e.g., the RTM). The assumption of ergodic conditions does result in the validity of the expected value relationship. In practice, the wavelength ranges sampled by different implementations of the other methods will also vary, which would also imply getting different results from each implementation. + +###### 6.1.3.5.2 GINTY calculations + +GINTY allows some of the assumptions required for Equation 6-13 with TINTY to be removed. Notably: + +- the assumption of ideal random mode coupling is not required; +- the assumption of a Gaussian source is not required; +- the assumption that the PMD is large compared to the width of the autocorrelation function is not required. + +Form the mean squared cross-correlation and autocorrelation envelopes, $\bar{E}_x^2(\tau)$ and $\bar{E}_0^2(\tau)$ as: + +$$\bar{E}_x^2(\tau) = \frac{1}{N} \sum_i E_{xi}^2(\tau) \quad \bar{E}_0^2(\tau) = \frac{1}{N} \sum_i E_{0i}^2(\tau) \quad (6-14)$$ + +where $N$ is the number of I/O-SOPs. + +Calculate the RMS width of the two sampled mean squared envelopes, $\sigma_0$ and $\sigma_x$ , respectively. A sample algorithm for this calculation is given in clause I.2. The mathematical definitions of these widths are: + +$$\sigma_x^2 = \frac{\int \tau^2(\tau) \langle E_x^2(\tau) \rangle d\tau}{\int \langle E_x^2(\tau) \rangle d\tau} \quad \sigma_0^2 = \frac{\int \tau^2(\tau) \langle E_0^2(\tau) \rangle d\tau}{\int \langle E_0^2(\tau) \rangle d\tau} \quad (6-15)$$ + +The expected value operator in the above equations is with respect to a uniform and random sampling of the I/O-SOPs. + +The $\text{PMD}_{\text{RMS}}$ value that is reported is: + +$$\text{PMD}_{\text{RMS}} = \left[ \frac{3}{2} (\sigma_x^2 - \sigma_0^2) \right]^{1/2} \quad (6-16)$$ + +Equation 6-16 relates to Equation 3-2 as: + +$$\frac{\int \Delta\tau^2(v) S_0^2(v) dv}{\int S_0^2(v) dv} = \frac{3}{2} (\sigma_x^2 - \sigma_0^2) \quad (6-17)$$ + +Using the ideal definitions of the RMS width terms from Equation 6-15, Equation 6-17 is exact for any DGD curve present at the time of measurement and any source spectral characteristics. The left side of Equation 6-17 is a spectrally weighted (by squared power) RMS calculation. + +Using the assumption of ergodic conditions: + +$$\langle \Delta\tau^2 \rangle = \left\langle \frac{\int \Delta\tau^2(v) S_0^2(v) dv}{\int S_0^2(v) dv} \right\rangle \quad (6-18)$$ + +#### 6.1.3.6 Presentation of the results + +The following details shall be presented: + +- a) Date. +- b) Fibre identification. +- c) Fibre type. +- d) Fibre length. +- e) Test set-up arrangement, including source type, wavelength, linewidth (FWHM). +- f) Launching technique. +- g) Type of fringe detection technique. +- h) Plot over the scanned range with fringe pattern (only if mode-coupling type is not random). +- i) Fibre deployment and environmental conditions (radius, stress, temperature, etc.). +- j) Mode-coupling type (random, mixed or negligible). +- k) Analysis method (TINTY or GINTY) +- l) $\text{PMD}_{\text{RMS}}$ , in picoseconds, or $\text{PMD}_{\text{AVG}}$ (specify which), in picoseconds, and PMD coefficient. If the degree of mode coupling is known, the coefficient may be given in picoseconds per kilometre or picoseconds per root kilometre. + +### 6.1.4 Third alternative test method: Fixed analyser technique + +#### 6.1.4.1 General + +This test method describes a procedure for measuring the PMD of single-mode optical fibres. It produces a single measurement value that represents the PMD over the measurement wavelength range of typically a few hundred nanometres. The method can be applied to both short and long fibres in the limits of both negligible and random polarization mode coupling. Under some circumstances, repeated measurements may be necessary to achieve satisfactory precision using this method. The procedure is restricted to wavelengths greater than or equal to that at which the fibre is effectively single mode. + +#### 6.1.4.2 Test apparatus + +See Figure 12 for a schematic diagram of the key components in a typical measurement system. + +![Figure 12 – Schematic diagram of equipment (typical). The figure contains three sub-diagrams labeled a), b), and c).](7d2d1d3870cd224c4430d19334557716_img.jpg) + +Figure 12 shows three schematic diagrams of equipment for measuring PMD: + +- a)** A schematic of the fixed analyser technique. A lamp passes through a chopper (producing a square wave) and then a monochromator. The output is connected to a computer. The light then passes through a polarizer, a test fibre, and an analyser. The signal from the analyser is sent to a detector, which is connected to a lock-in amplifier. The lock-in amplifier is also connected to the computer. +- b)** A schematic of a broadband source. A broadband source is connected to a polarizer, which is connected to a splice. This is followed by a test fibre, another splice, an analyser, and finally an optical spectrum analyser. +- c)** A schematic of a tunable laser. A tunable laser is connected to a polarizer, which is connected to a test fibre. The output of the test fibre is connected to a polarimeter. The polarimeter displays a Poincaré sphere and three waveforms. The text "G.650.2(15)\_F12" is visible in the bottom right corner. + +Figure 12 – Schematic diagram of equipment (typical). The figure contains three sub-diagrams labeled a), b), and c). + +Figure 12 – Schematic diagram of equipment (typical) + +##### **6.1.4.2.1 Light source** + +Use a light source which emits radiation at the intended measurement wavelengths, such as a broadband lamp, light emitting diode(s) or tunable laser(s). It shall be stable in intensity and spectral distribution over a time period long enough to perform the measurement. + +##### **6.1.4.2.2 Monochromator** + +Obtain a specified set of test wavelengths by filtering the light source with a monochromator as in Figure 12-a, or by using an optical spectrum analyser as the detector, as in Figure 12-b. This filtering is not needed when the source is a tunable laser (see Figure 12-c). The spectral distribution must be narrow enough to avoid major depolarization of the signal under the influence of the PMD of the fibre under test (see clauses 6.1.4.4.1.4 and 6.1.4.4.2.8). + +##### **6.1.4.2.3 Input optics** + +An optical lens system or SMF pigtail may be employed to excite the test fibre. The power coupled into the fibre shall be stable for the duration of the test. If pigtails are used, interference effects due to reflections should be avoided. This may require index-matching materials or angled cleaves. The pigtails shall be single mode. + +If an optical lens system is used, some suitable means, such as a vacuum chuck, shall be used to stably support the input end of the fibre. + +##### **6.1.4.2.4 Cladding mode stripper** + +Remove any cladding mode power from the test fibre. Under most circumstances, the fibre coating performs this function; otherwise, employ a device that extracts cladding mode power. + +##### **6.1.4.2.5 Output optics** + +All power emitted from the test fibre must be coupled onto the active region of the detection system (see Figure 12). An optical lens system, a butt splice to an SMF pigtail or an index-matched fibre-to-fibre coupling made directly to the detection system are examples of means that may be used. + +##### **6.1.4.2.6 Signal detection** + +For signal detection, use an optical detector that is linear and stable over the range of intensities and measurement times that are encountered in performing the measurement. A typical system might include synchronous detection by a chopper and lock-in amplifier, an optical power meter, an optical spectrum analyser or a polarimeter. To use the entire spectral range of the source, the detection system must have a wavelength range which includes the wavelengths produced by the light source. + +##### **6.1.4.2.7 Polarizer and analyser** + +The polarizer at the fibre input (Figure 12) is needed only if the launch beam is not already polarized (usually a 3 dB extinction ratio is sufficient). The angular orientation of the polarizers is not critical, but should remain fixed throughout the measurement. With negligible mode coupling, some adjustment of the polarizer orientation may be helpful in maximizing the amplitude of the oscillations in Figure 13-a. Alternatively, this may be achieved by rotation of the fibre(s) at splices or connectors. + +The analyser is not needed when a polarimeter is used for signal detection (Figure 12-c). + +#### **6.1.4.3 Measurement procedure** + +The test sample shall be a known length of a single-mode optical fibre that may or may not be cabled. The sample and pigtails must be fixed in position at a nominally constant temperature throughout the measurement. + +NOTE – Although the test sample is normally a fibre, this test can also be performed on discrete components. In this case, PMD coefficient is not relevant. + +Temperature stability of the test device may be observed by measuring the output power from the fibre at a fixed wavelength, with the output analyser in place. In a time period corresponding to a typical complete measurement, the output power change should be small relative to the changes produced by a wavelength increment. + +It is important to minimize deployment-induced mode coupling when measuring uncabled fibres, which is done in order to support the primary requirements of cabled fibre PMDQ. In this case, the fibre shall be supported in some manner (usually on a reel having a minimum wind radius of 150 mm), with essentially zero fibre tension (typically less than 5 g force), and no tensioned crossovers. These deployment requirements can limit the length that can be measured, depending on the spool diameter, and can make the measurement a destructive one. Multi-layer windings are possible, but should be qualified by comparison with single-layer results on shorter lengths. + +The measurement of uncabled fibre deployed on shipping spools is not recommended. PMD results with this deployment have been shown to be substantially less than what would be obtained in cable form for high PMD fibre and substantially greater than what would be obtained in cable form for low PMD fibre. + +Couple the input end of the fibre to the light source. Couple the output radiation from the fibre under test to the detection system. + +By making appropriate adjustments to the monochromator, optical spectrum analyser or tunable laser, inject each designated test wavelength $\lambda$ in turn into the fibre. The choice of wavelengths depends on the designated wavelength scan range and also on the analysis method (see clauses 6.1.4.4.1 and 6.1.4.4.2). + +Record the corresponding output signal for each wavelength. This process shall be accomplished without changing the launch and detector conditions. Call the received power $P_A(\lambda)$ , where A denotes the presence of the analyser. + +Remove the analyser from the beam and repeat the monochromator scan. Call this received power $P_{TOT}(\lambda)$ . This latter power can be used to eliminate the spectral dependence of the measurement system components and the test fibre loss. Typical plots of the ratio: + +$$R(\lambda) = \frac{P_A(\lambda)}{P_{TOT}(\lambda)} \quad (6-19)$$ + +are shown in Figure 13. + +An alternative procedure is to leave the analyser in place, but rotate it 90° with respect to the orientation used above. Calling the power received in this case $P_{ROT}(\lambda)$ , then: + +$$R(\lambda) = \frac{P_A(\lambda)}{P_A(\lambda) + P_{ROT}(\lambda)} \quad (6-20)$$ + +If a polarimeter is used as the detection element, the normalized Stokes parameters are measured versus wavelength. The three spectral functions are independent of the received power and are analysed by the same methods applied to $R(\lambda)$ (see clauses 6.1.4.4.1 and 6.1.4.4.2). Each normalized Stokes parameter then leads to a value of $\langle \Delta\tau \rangle$ . + +![Figure 13a: A graph showing the magnitude of the reflection coefficient R(λ) versus Wavelength (nm) for negligible mode coupling. The x-axis ranges from 1300 nm to 1600 nm with major ticks every 100 nm. The y-axis ranges from 0.0 to 1.0 with major ticks every 0.2. The curve shows a periodic oscillation with approximately 7 peaks and 6 troughs, indicating a regular pattern of mode coupling.](d68ecc44f3cfaed866a846f9fa4bdf38_img.jpg) + +Figure 13a: A graph showing the magnitude of the reflection coefficient R(λ) versus Wavelength (nm) for negligible mode coupling. The x-axis ranges from 1300 nm to 1600 nm with major ticks every 100 nm. The y-axis ranges from 0.0 to 1.0 with major ticks every 0.2. The curve shows a periodic oscillation with approximately 7 peaks and 6 troughs, indicating a regular pattern of mode coupling. + +a) Negligible mode coupling + +![Figure 13b: A graph showing the magnitude of the reflection coefficient R(λ) versus Wavelength (nm) for random mode coupling. The x-axis ranges from 1400 nm to 1600 nm with major ticks every 40 nm. The y-axis ranges from 0.0 to 1.0 with major ticks every 0.2. The curve shows a more irregular oscillation with varying peak and trough amplitudes compared to the negligible mode coupling case.](a844248c1fa0a79f187fc9aa111182f7_img.jpg) + +Figure 13b: A graph showing the magnitude of the reflection coefficient R(λ) versus Wavelength (nm) for random mode coupling. The x-axis ranges from 1400 nm to 1600 nm with major ticks every 40 nm. The y-axis ranges from 0.0 to 1.0 with major ticks every 0.2. The curve shows a more irregular oscillation with varying peak and trough amplitudes compared to the negligible mode coupling case. + +b) Random mode coupling + +G.650.2(15)\_F13 + +**Figure 13 – Typical data obtained in measuring PMD** + +#### 6.1.4.4 Calculations or interpretation of results + +One of the following two methods (clauses 6.1.4.4.1 and 6.1.4.4.2) shall be used for calculating PMD from the measurement data. + +##### 6.1.4.4.1 Extrema counting + +###### 6.1.4.4.1.1 PMD + +$R(\lambda)$ should be obtained at evenly spaced wavelength intervals. $E$ is the number of extrema within the window $\lambda_1 < \lambda < \lambda_2$ . Alternatively, $\lambda_1$ and $\lambda_2$ may be chosen to coincide with extrema, in which case $E$ is the number of extrema (including the ones at $\lambda_1$ and $\lambda_2$ ) minus one. + +$$\langle \Delta\tau \rangle = \frac{k E \lambda_1 \lambda_2}{2 (\lambda_2 - \lambda_1) c} \quad (6-21)$$ + +where $c$ is the speed of light in a vacuum, $k$ is a mode-coupling factor which equals 1.0 for negligible mode coupling (see clause 3.1.5.2) and 0.82 in the limit of random mode coupling (see clause 3.1.5.1). + +If a polarimeter is used as the detection element, take as the final value of $\langle \Delta\tau \rangle$ the average of the values derived from the three normalized Stokes parameter responses. The resulting value is to be interpreted as an average over the wavelength range $\lambda_1 < \lambda < \lambda_2$ . + +###### 6.1.4.4.1.2 Accuracy + +The best accuracy is obtained by making $(\lambda_2 - \lambda_1)$ large enough to ensure that $E \gg 1$ . This is especially important when there is random mode coupling (Figure 13-b) and less so otherwise (Figure 13-a). Values of $E$ in the range of 7 to 40 are typical. When $E$ is at the low end of this range, the percentage of uncertainties in both $E$ and the PMD become large. At the upper end of the range, instrumental broadening may result in some adjacent peaks not being resolved. + +Ideally, the scan window should be centred on the fibre's wavelength of use, and the window made wide enough to ensure that $E$ is greater than about 10 for the maximum PMD value of interest (where pass/fail is an issue). + +###### 6.1.4.4.1.3 Peak identification + +The identification of extrema in $R(\lambda)$ can be more difficult in the presence of noise or random mode coupling. This can be seen in the example of Figure 13-b. An algorithm with the following features is useful in identifying extrema: + +- 1) A polynomial is fitted to several adjacent points of $R(\lambda)$ to provide a smoothed curve. +- 2) An extremum is defined as a point where the wavelength derivative of this smoothed curve changes sign. + +Additional robustness can be built into the peak identification algorithm if needed. + +###### 6.1.4.4.1.4 Spectral resolution + +To ensure that all features in the optical spectrum are adequately resolved, the spectral resolution $\Delta\lambda$ should satisfy: + +$$\Delta\lambda / \lambda < (8\nu\Delta\tau)^{-1} \quad (6-22)$$ + +where $\nu$ is the optical frequency. $\Delta\lambda$ is the instrumental spectral width or the wavelength step size, whichever is larger. For $\lambda$ in the vicinity of 1 550 nm, Equation 6-22 reduces to the condition that $\Delta\lambda$ in nanometres should be less than the reciprocal of $\Delta\tau$ in picoseconds. + +##### 6.1.4.4.2 Fourier analysis + +###### 6.1.4.4.2.1 Overview + +In this method, a Fourier analysis of $R(\lambda)$ , usually expressed in the domain of optical frequency, $\nu$ , is used to derive PMD. The Fourier transform transforms this optical frequency domain data to the time domain. The Fourier transform yields direct information on the distribution of light arrival times, $\delta\tau$ . This data is post-processed as described below to derive the expected PMD, $\langle \Delta\tau \rangle$ , for the fibre under test. This method is applicable to fibres with negligible or random mode coupling (refer to clauses 6.1.4.4.2.4 and 6.1.4.4.2.5, respectively). + +###### 6.1.4.4.2.2 Data preprocessing and Fourier transformation + +To use this method, the Fourier transform normally requires equal intervals in optical frequency so that $R(\lambda)$ data is collected (as described in clause 6.1.4.3) at $\lambda$ values such that they form equal intervals in the optical frequency domain. Alternatively, data taken at equal $\lambda$ intervals may be fitted (e.g., by using a cubic spline fit) and interpolation used to generate these points, or more advanced spectral estimation techniques used. In each instance, the ratio $R(\lambda)$ at each $\lambda$ value used is calculated using Equations 6-19 or 6-20 as appropriate. + +Zero-padding or data interpolation and DC level removal may be performed on the ratio data, $R(\lambda)$ . Windowing the data may also be used as a preconditioning step before the Fourier transform. The Fourier transformation is now carried out to yield the amplitude data distribution $P(\delta\tau)$ for each value of $\delta\tau$ . + +###### 6.1.4.4.2.3 Transform data fitting + +Fourier transformed data at zero $\delta\tau$ has little meaning since, unless carefully removed, DC components in $R(\lambda)$ may be partially due to insertion loss of the analyser, for example. When the DC level is not removed, up to two data points are generally bypassed (not used) in any further calculations. A variable, $j$ , is defined so that the "first valid bin" above zero $\delta\tau$ that is included in calculations corresponds to $j = 0$ . + +In order to remove measurement noise from subsequent calculations, $P(\delta\tau)$ is compared to a threshold level $T_1$ , typically set to 200% of the RMS noise level of the detection system. It is now necessary to determine whether the fibre is negligibly or randomly mode coupled. + +If it is found that the first $X$ valid points of $P(\delta\tau)$ are all below $T_1$ , this indicates that $P(\delta\tau)$ must have discrete spike features characteristic of negligibly coupled fibres. Unless zero-padding is used in the Fourier analysis, $X = 3$ . In that case, the value of $X$ can be determined from 3 times the number of original data points divided by the total length of array after zero-padding. Use clause 6.1.4.4.2.4 to calculate PMD. If this is not the case, proceed to calculate PMD using clauses 6.1.4.4.2.5 or 6.1.4.4.2.6. + +###### 6.1.4.4.2.4 PMD calculation for fibres with negligible mode coupling + +For a negligibly coupled fibre (e.g., a high birefringence fibre) or for a birefringent component, $R(\lambda)$ resembles a chirped sine wave (Figure 13-a). Fourier transformation will give a $P(\delta\tau)$ output containing a discrete spike at a position corresponding to the relative pulse arrival time, $\delta\tau$ , the centroid of which is the PMD value $\langle\Delta\tau\rangle$ . + +To define the spike centroid $\langle\Delta\tau\rangle$ , those points where $P(\delta\tau)$ exceeds a second predetermined threshold level $T_2$ , typically set to 200% of the RMS noise level of the detection system, are used in Equation 6-23: + +$$\langle\Delta\tau\rangle = \frac{\sum_{e=0}^{M'} [P_e(\delta\tau)\delta\tau_e]}{\sum_{e=0}^{M'} [P_e(\delta\tau)]} \quad (6-23)$$ + +where $M' + 1$ is the number of data points of $P$ within the spike which exceed $T_2$ . $\langle\Delta\tau\rangle$ in Equation 6-23 is typically quoted in picoseconds. If the device under test is a fibre of length $L$ , the PMD coefficient may be calculated using clause 3.1.5.2. If no spike is detected (i.e., $M' = 0$ ), then PMD is zero. Other parameters such as the RMS spike width or spike peak value may be reported. + +If the device under test contains one or more birefringent elements, more than one spike will be generated. For a number $n$ concatenated fibres/devices, $2^{(n-1)}$ spikes will be obtained. + +###### 6.1.4.4.2.5 PMD calculation for fibres with random mode coupling + +In instances of random mode coupling, $R(\lambda)$ becomes a complex waveform similar to Figure 13-b, the exact characteristics being based on the actual statistics of the coupling process within the fibre or cable. The Fourier transformed data now becomes a distribution $P(\delta\tau)$ representing the autocorrelation of the probability distribution of light pulse arrival times, $\delta\tau$ , in the fibre. + +Counting up from $j = 0$ , determine the first point of $P$ which exceeds $T_1$ , and which is followed by at least $X$ data points which fall below $T_1$ . This point represents the last significant point in (i.e., the "end" of) the distribution $P(\delta\tau)$ , for a randomly mode-coupled fibre, that is not substantially affected by measurement noise. The $\delta\tau$ value for this point is denoted $\delta\tau_{\text{last}}$ , and the value of $j$ at $\delta\tau_{\text{last}}$ is denoted + +$M''$ . This fibre is randomly mode coupled. The square root of the second moment, $\sigma_R$ , of this distribution defines the fibre PMD $\langle \Delta\tau \rangle$ , and is given by: + +$$\langle \Delta\tau \rangle = \sigma_R = \left\{ \frac{\sum_{j=0}^{M''} [P_j(\delta\tau) \delta\tau_j^2]}{\sum_{j=0}^{M''} [P_j(\delta\tau)]} \right\}^{1/2} \quad (6-24)$$ + +The $\langle \Delta\tau \rangle$ value given by Equation 6-24 is typically quoted in picoseconds and normalized to picoseconds per root kilometre using clause 3.1.5.1. An example of the Fourier transform output obtained in a 25 km fibre with random mode coupling is shown in Figure 14. + +![Figure 14: PMD using Fourier analysis. A plot showing Probability (A.U.) on the y-axis (0 to 0.05) versus Relative pulse arrival time (ps) on the x-axis (0 to 0.5). The plot displays two data series: FFT magnitude (squares) and Gaussian fit (triangles). The FFT magnitude shows a peak at j=0 (approx. 0.042) and a minimum at j=M''=9 (approx. 0.0015). The Gaussian fit is a smooth curve. Annotations include: X^2 = 22.61, Gaussian; PMD = 0.167 ps (second moment); PMD coefficient = 0.0334 ps/km^1/2; Threshold 0.0015.](c53adc66eab40abd5f8b9107d950ad04_img.jpg) + +The figure is a line graph with markers. The y-axis is labeled 'Probability (A.U.)' and ranges from 0 to 0.05 in increments of 0.005. The x-axis is labeled 'Relative pulse arrival time (ps)' and ranges from 0 to 0.5 in increments of 0.05. There are two data series: 'FFT magnitude' represented by square markers and 'Gaussian fit' represented by triangle markers. The FFT magnitude starts at approximately 0.042 at x=0.07 (labeled j=0), drops to a minimum of about 0.0015 at x=0.36 (labeled j=M''=9), and then slightly increases. The Gaussian fit is a smooth curve that starts at approximately 0.033 at x=0.07 and decreases monotonically. There are three text boxes: one in the top right stating 'X^2 = 22.61, Gaussian'; one in the middle right stating 'PMD = 0.167 ps (second moment)' and 'PMD coefficient = 0.0334 ps/km^1/2'; and one in the bottom right stating 'Threshold 0.0015'. A legend at the bottom shows a square for 'FFT magnitude' and a triangle for 'Gaussian fit'. A small code 'G.650.2(15)\_F14' is in the bottom right corner. + +Figure 14: PMD using Fourier analysis. A plot showing Probability (A.U.) on the y-axis (0 to 0.05) versus Relative pulse arrival time (ps) on the x-axis (0 to 0.5). The plot displays two data series: FFT magnitude (squares) and Gaussian fit (triangles). The FFT magnitude shows a peak at j=0 (approx. 0.042) and a minimum at j=M''=9 (approx. 0.0015). The Gaussian fit is a smooth curve. Annotations include: X^2 = 22.61, Gaussian; PMD = 0.167 ps (second moment); PMD coefficient = 0.0334 ps/km^1/2; Threshold 0.0015. + +Figure 14 – PMD using Fourier analysis + +###### 6.1.4.4.2.6 PMD calculation for mixed coupling fibre systems + +There may be instances where both negligibly coupled fibre or components and randomly coupled fibre(s) are concatenated to form the system under test. In this case, both centroid determination (clause 6.1.4.4.2.4) and the second moment derivation (clause 6.1.4.4.2.5) may be required. Note that spikes in $P(\delta\tau)$ may only be determined beyond the $\delta\tau_{last}$ computed. + +###### 6.1.4.4.2.7 Spectral range + +For randomly coupled fibres, sufficient spectral range must be used to form the spectral ensemble (average) with sufficient precision. The statistical uncertainty may be minimized by using the widest possible spectral range (e.g., at least 200 nm). The precision required and therefore spectral range must be specified prior to the measurement. The maximum usable range is limited by the fibre cut-off wavelength (1 270 nm or below) at the short ( $\lambda_1$ ) end, and by the detector responsivity roll-off at the high ( $\lambda_2$ ) end (e.g., 1 700 nm). + +In addition, very low $\delta\tau$ values will give very long periods in $R(\lambda)$ , and the spectral range $\lambda_1$ to $\lambda_2$ must cover at least two complete cycles. The spectral range covered defines the smallest $\delta\tau$ value that can be resolved in $P(\delta\tau)$ , $\delta\tau_{min}$ : + +$$\delta\tau_{\min} = \frac{2\lambda_1\lambda_2}{(\lambda_2 - \lambda_1)c} \quad (6-25)$$ + +where the factor 2 is introduced to allow for the fact that two data points in $P$ at and adjacent to zero are generally ignored (see clause 6.1.4.4.2.3). For example, for $\lambda_1 = 1\,270\text{ nm}$ , $\lambda_2 = 1\,700\text{ nm}$ , $\delta\tau_{\min} = 0.033\text{ ps}$ . + +For negligibly coupled high PMD fibres with ratio data $R(\lambda)$ resembling Figure 13-a, the requirement for spectral averaging described above may be relaxed, and the spectral range reduced [e.g., $(\lambda_2 - \lambda_1) \sim 30\text{ nm}$ ] in order to allow variation of PMD with wavelength to be examined. + +###### 6.1.4.4.2.8 Wavelength step size and spectral resolution + +To ensure that all features (frequencies) in $R(\lambda)$ are adequately resolved, the monochromator step size, expressed in the optical frequency domain ( $\Delta\nu$ ) must be a factor of two smaller than the oscillation frequency corresponding to the maximum $\delta\tau$ measured (Nyquist condition): + +$$\delta\tau_{\max} = 1/(2 \cdot \Delta\nu) \quad (6-26)$$ + +If, from the Fourier transform, it is evident that significant energy is present near to $\delta\tau_{\max}$ [i.e., that $R(\lambda)$ appears to be "aliased"], it will be necessary to reduce the step size $\Delta\nu$ (if possible) and repeat the measurement. + +The monochromator spectral linewidth (resolution) expressed in optical frequency units is generally equal to or smaller than the smallest $\Delta\nu$ value to be used (corresponding to the largest $\delta\tau$ value to be measured). + +For example, for $\delta\tau_{\max} = 1.34\text{ ps}$ , a monochromator linewidth of $3\text{ nm}$ at $1\,550\text{ nm}$ ( $\Delta\nu = 374\text{ GHz}$ ) is typical. + +##### 6.1.4.4.3 Cosine Fourier analysis + +This analysis is based on the observation that the cosine Fourier transform of the spectrum emitted from the analyser is the fringe pattern of the interferogram. The difference between fringe patterns generated by the analyser being set at two orthogonal settings is the cross-correlation function. For an infinite spectrum into the analyser, the autocorrelation function would have zero width. In practice, the finite source spectrum in the optical frequency domain (finite linewidth) acts as a windowing function which produces a non-zero autocorrelation function width in the time domain. + +The analysis of the squared cross-correlation and autocorrelation functions found in the GINTY analysis of clause 6.1.3 shows that the difference in squared RMS widths of these functions is proportional to the square of the spectrally weighted RMS (by squared power) of the DGD values. (See Equation 6-18.) + +The result is independent of the spectral shape which means that the details of the windowing function are fully taken into account. It is also independent of the degree of mode coupling, which means that no changes in algorithm are needed to treat the different regimes. + +The result is limited by the spectral width and optical frequency increment that is measured. As the PMD increases, the frequency increment must be decreased. At some limit it would be more practical to use the GINTY. + +The analysis reports the $\text{PMD}_{\text{RMS}}$ metric. If random mode coupling is found, the result can be converted to $\text{PMD}_{\text{AVG}}$ using Equation 3-3. + +###### 6.1.4.4.3.1 Overview + +The measurement of the powers emitted from the analyser set at two orthogonal settings is required. The ratio, $R$ , associated with Equation 6-20 is modified to: + +$$R(v) = \frac{P_A(v) - P_B(v)}{P_A(v) + P_B(v)} \quad (6-27)$$ + +where $v = c/\lambda$ is the optical frequency, in terahertz. + +If a polarimeter is used, the three normalized output Stokes vector elements are equivalent to three independent normalized ratios equivalent to that represented by Equation 6-27. Each Stokes vector element is the difference in powers between orthogonal analyser settings. The three elements are different in that the base settings are also orthogonal. + +The data are multiplied by a windowing function, $W(v)$ , that goes to zero smoothly at the edges. Both $R(v)W(v)$ and $W(v)$ are put into arrays with zero padding at lower, unmeasured frequencies. Fast cosine Fourier transforms (FCFTs) are applied to each array to obtain the time domain fringe envelopes, $r(t)w(t)$ and $w(t)$ . These are squared to obtain the squared cross-correlation and autocorrelation envelopes, $E_x^2$ and $E_0^2$ , respectively. When multiple ratio functions ( $N$ ) are available from different combinations of input polarizer setting and base analyser settings (or different Stokes output vector elements), using for instance I/O SOP scrambling, form the mean square envelopes as: + +$$\bar{E}_x^2 = \frac{1}{N} \sum_i E_{xi}^2 \quad \bar{E}_0^2 = \frac{1}{N} \sum_i E_{0i}^2 \quad (6-28)$$ + +Using the RMS calculation of clause I.2, calculate the RMS widths, $\sigma_x$ and $\sigma_0$ of these two functions. The $\text{PMD}_{\text{RMS}}$ value is calculated as: + +$$\text{PMD}_{\text{RMS}} = \left[ \frac{3}{2} (\sigma_x^2 - \sigma_0^2) \right]^{1/2} \quad (6-29)$$ + +It is related to the spectrally weighted (by squared window value) RMS of the DGDs as: + +$$\langle \text{PMD}_{\text{RMS}} \rangle = \frac{\int \Delta\tau^2(v) W^2(v) dv}{\int W^2(v) dv} \quad (6-30)$$ + +The expected value operator is with respect to random I/O SOPs. + +###### 6.1.4.4.3.2 Details + +This clause explains some of the details with respect to the measured frequency window, the frequency increment, $\Delta v$ , frequency shifting, and the result of the FCFT. An example of a FCFT algorithm may be found in [b-Press 1992]. + +The data must be available in uniform frequency increments. The number of data points, including zero pad values, must be $1 + 2^k$ , with $k$ an integer. + +If the $n_m$ data measured data points are not taken in uniform frequency increments, they may be fitted to a polynomial such as a spline for interpolation. A cubic spline with $n_m - 3$ uniform segments will fit all the data perfectly and allow interpolation. + +Given that the measured data are bounded by $v_{\min M}$ and $v_{\max M}$ and the fact that the minimum optical frequency is well above zero, the application of frequency shifting can be used to reduce the size of the arrays that are processed. The boundaries of the frequencies used in the calculation array can be selected by any choice of $n$ such that: + +$$v_{\max} \frac{n-1}{n} = v_{\min} \leq v_{\min M}, \quad v_{\max} = v_{\max M} \quad (6-31)$$ + +and $n$ is a positive integer. + +The frequency values less than the measured frequency are filled with zeros. + +Following the FCFT, the array will contain the time domain fringe pattern from times of 0 to $t_{\max} = \Delta t 2^k$ , where the time increment, $\Delta t$ , is given as: + +$$\Delta t = \frac{n}{2v_{\max}} = \frac{1}{2(v_{\max} - v_{\min})} \quad (6-32)$$ + +The fringe pattern that would be obtained from interferometry extends to negative time values as well as positive time values. The value at a given negative time is equal to the value at the positive time. The function is even and symmetric about zero. This can lead to simplifying the calculation of RMS since time zero is known. + +The selection of the frequency shift should be done keeping in mind that the RMS width calculation needs some time domain values that are less than the minimum $\text{PMD}_{\text{RMS}}$ that is measurable. + +The frequency increment, $\Delta v$ , is also related to the number of points sampled, the frequency shift and the maximum $\text{PMD}_{\text{RMS}}$ that is to be measured. It is given as the following, along with the constraint as: + +$$\Delta v = \frac{v_{\max} - v_{\min}}{2^k} \leq \frac{1}{24 \text{PMD}_{\text{RMS-max}}} \quad (6-33)$$ + +The constraint in Expression 6-33 is consistent with Equation 6-22. The spectral width of the filtered source should be half of this value. When the actual scan is done in equal wavelength increments, the wavelength increment at the lower end of the range should be consistent with the constraint of Equation 6-33. + +The windowing function, $W(v)$ , can technically be any function, including a square function. The function that is chosen should be one that minimizes the value of $\sigma_0$ . Functions that do this proceed to zero at the edges in a continuous way and should also have the first derivative proceed to zero at the edges. This will minimize the ringing that can increase $\sigma_0$ . + +###### 6.1.4.4.3.3 Examples + +Table 1 shows a sample calculation spreadsheet. The wavelength extrema and $k$ are centred. For each of several possible frequency shift values, $n$ , the other parameters are calculated. $\text{PMD}_{\min}$ is calculated as $3\Delta t$ . The effective shift in terms of $\Delta\lambda$ at the lower wavelength limit is also presented. Clearly there are trade-offs, depending on the range of $\text{PMD}_{\text{RMS}}$ values that are to be measured. In general, the broader the wavelength range and the smaller the frequency increment, the better. + +**Table 1 – Cosine transform calculations** + +| $c$ : 299792.5 nm/ps
$k$ : 11
$npt$ : 2 048 (Note) | | | | | | | | | | | +|----------------------------------------------------------|-----------------|-----------------|--------------------------|------------------|------------------|-----------------------|--|--|--|--| +| Wavelengths (nm) | | | Frequencies (THz) | | | | | | | | +| Max | 1 700 | 230.609 6 | | | | | | | | | +| Min | 1 300 | 176.348 5 | | | | | | | | | +| Frequency shift | | | | | | | | | | | +| $n$ | $v_{min}$ (THz) | $\Delta t$ (ps) | $\Delta v$ (THz) | $PMD_{min}$ (ps) | $PMD_{max}$ (ps) | $\Delta \lambda$ (nm) | | | | | +| 1 | 0 | 0.002 168 | 0.112 602 | 0.006 504 | 0.370 034 | 0.635 076 | | | | | +| 2 | 115.304 807 7 | 0.004 336 | 0.225 205 | 0.013 009 | 0.185 017 | 1.270 772 | | | | | +| 3 | 153.739 743 6 | 0.006 504 | 0.337 807 | 0.019 513 | 0.123 345 | 1.907 090 | | | | | +| 4 | 172.957 211 5 | 0.008 673 | 0.450 409 | 0.026 018 | 0.092 508 | 2.544 031 | | | | | +| 5 | 184.487 692 3 | 0.010 841 | 0.563 012 | 0.032 522 | 0.074 007 | 3.181 596 | | | | | +| 6 | 192.174 679 5 | 0.013 009 | 0.675 614 | 0.039 027 | 0.061 672 | 3.819 785 | | | | | +| 7 | 197.665 384 6 | 0.015 177 | 0.788 216 | 0.045 531 | 0.052 862 | 4.458 599 | | | | | +| 8 | 201.783 413 5 | 0.017 345 | 0.900 819 | 0.052 036 | 0.046 254 | 5.098 039 | | | | | + +NOTE – $npt$ is the number of points to be cosine transformed, and is equal to $2^k$ . The number of points in the test is usually less than this and the space not filled with actual data are filled with zero. + +The following illustrates the results for what might be obtained from a fibre with $PMD_{RMS} = 0.2$ ps. The mean cross-correlation and mean autocorrelation envelopes from a single scan using a windowing function that is Gaussian with a standard deviation of 23 nm are shown in Figure 15. The result is from a simulation of a fibre with ideal random mode coupling. The measured result for this simulation was 0.185 ps. + +![Figure 15 shows two plots of Power² versus Time (ps). The left plot (Cross-correlation) shows a sharp peak at approximately 0.185 ps, with a maximum value of about 7. The right plot (Autocorrelation) shows a broader peak centered at 0 ps, with a maximum value of about 60. Both plots have an x-axis ranging from 0 to 0.7 ps. The right plot is labeled G.650.2(15)_F15.](cfc852835f2d91bea8dc074568937e22_img.jpg) + +Figure 15 shows two plots of Power² versus Time (ps). The left plot (Cross-correlation) shows a sharp peak at approximately 0.185 ps, with a maximum value of about 7. The right plot (Autocorrelation) shows a broader peak centered at 0 ps, with a maximum value of about 60. Both plots have an x-axis ranging from 0 to 0.7 ps. The right plot is labeled G.650.2(15)\_F15. + +**Figure 15 – Cross-correlation and autocorrelation functions** + +#### **6.1.4.5 Presentation of the results** + +The following details shall be presented: + +- a) Identification of the fibre or cable measured. +- b) Test length. +- c) PMD (typically in picoseconds). If the degree of mode coupling is known, the PMD coefficient may be given in picosecond per kilometre (negligible mode coupling) or picosecond per root kilometre (random mode coupling). +- d) The wavelength range over which the measurement was performed, and the wavelength or frequency step size. +- e) The physical configuration of the fibre or cable sample. +- f) Mode-coupling type, e.g., deterministic, semi-random or random. +- g) When an average PMD has been obtained from repeated measurements of the sample, record the number of measurements performed. + +## **6.2 Test methods for non-linear attributes** + +Under study. + +# Appendix I + +## Determination of PMD delay from an interferogram + +(This appendix does not form an integral part of this Recommendation.) + +This appendix presents two methods for the determination of the RMS width from fringe envelopes. These methods are mainly used for the interferometric method of measuring PMD. Clause I.1 is for an envelope with the autocorrelation peak present and is suitable for the TINTY analysis. Clause I.2 is for envelopes without this peak and is suitable for the GINTY analysis. + +### I.1 RMS calculation for TINTY + +Figure I.1 shows a fringe envelope with an autocorrelation peak in the centre. + +![Figure I.1: A plot of Measured intensity versus Mirror position t_j (ps). The plot shows a noisy fringe envelope with a sharp central peak. Four points are marked on the curve: t_{jmin} on the left shoulder, t_j on the right shoulder, t_{jmin} at the start of the envelope on the left, and t_{jmax} at the end of the envelope on the right. The y-axis ranges from 0 to 1.2, and the x-axis is labeled with mirror position t_j (ps). A small label 'G.650.2(07)_FI.1' is in the bottom right corner of the plot area.](031e354d9de9563c9f650e3e4fcba16d_img.jpg) + +Figure I.1: A plot of Measured intensity versus Mirror position t\_j (ps). The plot shows a noisy fringe envelope with a sharp central peak. Four points are marked on the curve: t\_{jmin} on the left shoulder, t\_j on the right shoulder, t\_{jmin} at the start of the envelope on the left, and t\_{jmax} at the end of the envelope on the right. The y-axis ranges from 0 to 1.2, and the x-axis is labeled with mirror position t\_j (ps). A small label 'G.650.2(07)\_FI.1' is in the bottom right corner of the plot area. + +**Figure I.1 – Parameters for interferogram analysis** + +Let $\tilde{I}_j$ denote the measured intensity of the fringe envelope at increasing positions $t_j$ , $j = 1 \dots N$ , with $[t_j]$ in picoseconds. + +#### Step 1 – Computation of the zero intensity $\tilde{I}_0$ and the noise amplitude $Na$ + +Definition: $N_5 = \text{round } (5 N/100)$ + +$$\tilde{I}_0 = \frac{\sum_{j=1}^{N_5} (\tilde{I}_j + \tilde{I}_{N-j})}{2N_5} \quad (\text{I-1})$$ + +$$X_2 = \frac{\sum_{j=1}^{N_5} (\tilde{I}_j^2 + \tilde{I}_{N-j}^2)}{2N_5} \quad (\text{I-2})$$ + +$$Na = \sqrt{X_2 - \tilde{I}_0^2} \quad (\text{I-3})$$ + +#### **Step 2 – Definition of the shifted intensity $I_j$** + +$$I_j := \tilde{I}_j - \tilde{I}_0 \text{ if } \tilde{I}_j - \tilde{I}_0 > 4Na \quad (\text{I-4})$$ + +$$I_j := 0 \text{ if } \tilde{I}_j - \tilde{I}_0 \leq 4Na \quad (\text{I-5})$$ + +#### **Step 3 – Computation of the centre $C$ of the interferogram** + +$$C = \frac{\sum_{j=1}^N t_j I_j}{\sum_{j=1}^N I_j} \quad (\text{I-6})$$ + +#### **Step 4 – Removal of the central autocorrelation peak** + +Definition: $j_l$ : = the largest subscript $j$ such that $C - t_j > \tau_c$ (I-7) + +$j_r$ : = the smallest subscript $j$ such that $t_j - C > \tau_c$ (I-8) + +where $\tau_c$ is the source coherence time. + +NOTE 1 – For cross-correlation interferograms, the following definition shall be applied: + +$$j_r := j_l + 1 \quad (\text{I-9})$$ + +#### **Step 5 – Computation of the second moment $S$ of the interferogram** + +$$S = \frac{1}{2} \left\{ \sqrt{\frac{\sum_{j=1}^{j_l} (t_j - C)^2 I_j}{\sum_{j=1}^{j_l} I_j}} + \sqrt{\frac{\sum_{j=j_r}^N (t_j - C)^2 I_j}{\sum_{j=j_r}^N I_j}} \right\} \quad (\text{I-10})$$ + +#### **Step 6 – Truncate the interferogram** + +Set $j_{\min}$ to the largest subscript $j$ such that $C - t_j > 2S$ (I-11) + +Set $j_{\max}$ to the smallest subscript $j$ such that $t_j - C > 2S$ (I-12) + +#### **Step 7 – Computation of the second moment $\sigma_\varepsilon$ of the truncated interferogram** + +$$\sigma_\varepsilon = \frac{1}{2} \left\{ \sqrt{\frac{\sum_{j=j_{\min}}^{j_l} (t_j - C)^2 I_j}{\sum_{j=j_{\min}}^{j_l} I_j}} + \sqrt{\frac{\sum_{j=j_r}^{j_{\max}} (t_j - C)^2 I_j}{\sum_{j=j_r}^{j_{\max}} I_j}} \right\} \quad (\text{I-13})$$ + +#### **Step 8 – Computation of the $\sigma$ of the Gaussian $\exp(-(t - C)^2 / 2\sigma^2)$ such that:** + +$$\sigma_\varepsilon = \frac{1}{2} \left\{ \sqrt{\frac{\int_{t_{j_{\min}}}^{t_{j_l}} (t - C)^2 \exp[-(t - C)^2 / 2\sigma^2] dt}{\int_{t_{j_{\min}}}^{t_{j_l}} \exp[-(t - C)^2 / 2\sigma^2] dt}} + \sqrt{\frac{\int_{t_{j_r}}^{t_{j_{\max}}} (t - C)^2 \exp[-(t - C)^2 / 2\sigma^2] dt}{\int_{t_{j_r}}^{t_{j_{\max}}} \exp[-(t - C)^2 / 2\sigma^2] dt}} \right\} \quad (\text{I-14})$$ + +#### Step 9 – Determination of PMDRMS $\langle \Delta\tau^2 \rangle^{1/2}$ + +$$\text{PMD}_{\text{RMS}} = \langle \Delta\tau^2 \rangle^{1/2} = \sqrt{\frac{3}{4}} \sigma \quad (\text{I-15})$$ + +NOTE 2 – For appropriately measured interferograms, it can be shown that $\frac{\sigma_\varepsilon}{\sigma} \approx \sqrt{\frac{3}{4}}$ . + +### I.2 RMS calculation for GINTY + +The following algorithm results in a robust RMS width for either the composite square cross-correlation or autocorrelation envelopes using method D (GINTY). + +The algorithm is iterative. For a given iteration, the full data array is divided into two sets: The central portion, M, containing the signal and the tails, T, which contain noise. Each iteration results in different definitions for these sets. The result converges when either the computed RMS width ceases to vary or when the set definitions stabilize. For an iteration, the number of data points in each set are denoted as $N_M$ and $N_T$ . + +Let $\tilde{I}_j$ denote the measured intensity of the envelope at increasing positions $t_j$ (ps), (ps), $j = 1 \dots N$ . + +The initial definition of the set T is the first and last 5% of the whole array. + +#### Step 1 – Computation of the zero $\tilde{I}_0$ + +$$\tilde{I}_0 = \sum_{j \in T} \tilde{I}_j / N_T \quad (\text{I-16})$$ + +#### Step 2 – Definition of the shifted intensity $I_j$ + +$$I_j = \tilde{I}_j - \tilde{I}_0 \quad \text{all } N \quad (\text{I-17})$$ + +#### Step 3 – Computation of the centre $C$ of the interferogram + +$$C = \frac{\sum_{j \in M} t_j I_j}{\sum_{j \in M} I_j} \quad (\text{I-18})$$ + +#### Step 4 – Computation of the RMS width $\sigma$ of the squared envelope + +$$\sigma^2 = \frac{\sum_{j \in M} (t_j - C)^2 I_j}{\sum_{j \in M} I_j} \quad (\text{I-19})$$ + +#### Step 5 – Redefine the sets + +Define M as the set of points for which $C - 4\sigma \leq t_j \leq C + 4\sigma$ . + +Define T as the rest of the points. + +#### Step 6 – Repeat steps 1 to 5 until the results converge + +$$\frac{\sigma_\varepsilon}{\sigma} \approx \sqrt{\frac{3}{4}}$$ + +# Appendix II + +## Non-linear attributes + +(This appendix does not form an integral part of this Recommendation.) + +### II.1 Background + +Non-linear interactions between the signal and the silica fibre transmission medium begin to appear as optical signal powers and are increased to achieve longer span lengths at high bit rates. Consequently, non-linear fibre behaviour has emerged as an important consideration, both in high capacity systems and in long unregenerated routes. These non-linearities can be generally categorized as either scattering effects (stimulated Brillouin scattering and stimulated Raman scattering) or effects related to the Kerr effect, that is, the intensity dependence of the refractive index (self-phase modulation, cross-phase modulation, modulation instability, soliton formation and four wave mixing). A variety of parameters influence the severity of these non-linear effects, including fibre dispersion characteristics, the effective area of the fibre, the number and spacing of channels in multiple channel systems, overall unregenerated system length, the degree of longitudinal uniformity of the fibre characteristics, as well as signal intensity and source linewidth. + +### II.2 Effective area ( $A_{\text{eff}}$ ) + +Effective area is a parameter that is closely related to optical fibre non-linearities that will affect the transmission quality of the optical fibre systems, especially in long-haul optically amplified systems. Effective area $A_{\text{eff}}$ is defined as follows: + +$$A_{\text{eff}} = \frac{\left[ 2\pi \int_0^\infty I(r) r dr \right]^2}{\int_0^\infty I(r)^2 r dr} \quad (\text{II-1})$$ + +where $I(r)$ is the field intensity distribution of the fundamental mode of the fibre at radius $r$ . The integration of Equation II-1 is carried out over the entire cross-sectional area of the fibre. For example, if we make a Gaussian approximation such that: + +$$I(r) = \exp(-2r^2/w^2) \quad (\text{II-2})$$ + +where $2w$ is the mode field diameter (MFD), then Equation II-1 can be analytically integrated and gives: + +$$A_{\text{eff}} = \pi w^2 \quad (\text{II-3})$$ + +The Gaussian approximation is accurate for ITU-T G.652 and ITU-T G.654 step-index fibres near the LP11 cut-off, but for ITU-T G.652 and ITU-T G.654 fibres at much longer wavelengths, and in the case of ITU-T G.653 dispersion shifted fibres, $A_{\text{eff}}$ cannot be accurately estimated from Equation II-3. + +A more general but empirical relationship between $A_{\text{eff}}$ and $w$ is [b-Namihira 1994]: + +$$A_{\text{eff}} = k\pi w^2 \quad (\text{II-4})$$ + +where $k$ is a correction factor. + +### II.3 Correction factor $k$ + +In the experiment, the MFD was measured by the variable aperture test method. From the far-field pattern (FFP) of the output optical power $P(r)$ , it was then possible to calculate the near-field pattern (NFP) using an inverse Hankel transformation. $A_{\text{eff}}$ is then derived from the NFP by using Equation II-1. + +The correction factor $k$ in Equation II-4 depends on the wavelength and on fibre parameters, such as refractive index profiles, MFD and zero-dispersion wavelength. + +Figure II.1 shows examples of measured wavelength dependence of MFD and $A_{\text{eff}}$ for ITU-T G.652 and ITU-T G.653 fibres in the 1 200–1 600 nm wavelength regions. Figure II.2 gives examples of calculated and measured wavelength dependence of MFD, $A_{\text{eff}}$ , and the correction factor $k$ for ITU-T G.652, ITU-T G.653 and ITU-T G.654 fibres in this same wavelength range. + +The ranges of the correction factor $k$ for these examples are summarized in Table II.1. + +For other fibre designs that may be developed for optical submarine and wavelength division multiplexing (WDM) applications, the relationship of $A_{\text{eff}}$ to $w$ may vary, and should be determined using Equation II-1. + +Figure II.3 shows the wavelength dependence of $A_{\text{eff}}$ for ITU-T G.653 (dispersion-shifted single-mode fibre; DSF) and ITU-T G.655 (NZ-DSF) fibres in the 1 520–1 580 nm wavelength range for WDM applications. + +The average $k$ values and standard deviation were found to be around $0.953 \pm .005$ for the ITU-T G.653 fibres, and $1.09 \pm .070$ for the ITU-T G.655 fibres. + +**Table II.1 – Summary of correction factor $k$ of $A_{\text{eff}}$ and MFD ( $= 2w$ ) for ITU-T G.652, ITU-T G.653 and ITU-T G.654 fibres based on the examples in Figure II.2** + +| Fibre types | Wavelength $\lambda$ | | +|----------------------------------|--------------------------|--------------------------| +| | $\sim 1\ 310\ \text{nm}$ | $\sim 1\ 550\ \text{nm}$ | +| ITU-T G.652 | 0.970 ~ 0.980 (Note) | 0.960 ~ 0.970 | +| ITU-T G.654 | ... | 0.975 ~ 0.985 (Note) | +| ITU-T G.653 | 0.940 ~ 0.950 | 0.950 ~ 0.960 (Note) | +| NOTE – Optimum wavelength range. | | | + +![A dual-axis line graph showing the wavelength dependence of MFD and A_eff for ITU-T G.652 (SMF) and ITU-T G.653 (DSF) fibres. The x-axis is Wavelength λ (nm) from 1100 to 1800. The left y-axis is MFD (μm) from 5 to 11. The right y-axis is A_eff (μm²) from 20 to 90. ITU-T G.652 (SMF) data is shown with squares (A_eff) and solid squares (MFD). ITU-T G.653 (DSF) data is shown with open triangles (A_eff) and solid triangles (MFD). Arrows indicate which curve corresponds to which y-axis.](25fab88fda841d5eec316c440656187e_img.jpg) + +ITU-T G.652 (SMF) + +UIT-T G.653 (DSF) + +MFD ( $\mu\text{m}$ ) + +$A_{\text{eff}}$ ( $\mu\text{m}^2$ ) + +Wavelength $\lambda$ (nm) + +G.650.2(15)\_FII.1 + +■ $A_{\text{eff}}$ ITU-T G.652 (SMF) [Step index] + ▲ MFD ITU-T G.652 (SMF) [Step index] + △ $A_{\text{eff}}$ ITU-T G.653 (DSF) [Non-step index] + ▲ MFD ITU-T G.653 (DSF) [Non-step index] + +| Wavelength $\lambda$ (nm) | ITU-T G.652 (SMF) $A_{\text{eff}}$ ( $\mu\text{m}^2$ ) | ITU-T G.652 (SMF) MFD ( $\mu\text{m}$ ) | ITU-T G.653 (DSF) $A_{\text{eff}}$ ( $\mu\text{m}^2$ ) | ITU-T G.653 (DSF) MFD ( $\mu\text{m}$ ) | +|---------------------------|--------------------------------------------------------|-----------------------------------------|--------------------------------------------------------|-----------------------------------------| +| 1200 | ~58 | ~8.5 | ~28 | ~5.8 | +| 1300 | ~65 | ~9.0 | ~32 | ~6.0 | +| 1400 | ~72 | ~9.5 | ~38 | ~6.5 | +| 1500 | ~78 | ~10.0 | ~45 | ~7.2 | +| 1600 | ~85 | ~10.5 | ~52 | ~8.0 | + +A dual-axis line graph showing the wavelength dependence of MFD and A\_eff for ITU-T G.652 (SMF) and ITU-T G.653 (DSF) fibres. The x-axis is Wavelength λ (nm) from 1100 to 1800. The left y-axis is MFD (μm) from 5 to 11. The right y-axis is A\_eff (μm²) from 20 to 90. ITU-T G.652 (SMF) data is shown with squares (A\_eff) and solid squares (MFD). ITU-T G.653 (DSF) data is shown with open triangles (A\_eff) and solid triangles (MFD). Arrows indicate which curve corresponds to which y-axis. + +**Figure II.1 – Example of measured wavelength dependence of $A_{\text{eff}}$ and MFD ( $= 2w$ ) of ITU-T G.652 and ITU-T G.653 fibres** + +![Figure II.2: A plot showing the wavelength dependence of the correction factor k_n = A_eff / pi W^2 for various optical fibers. The y-axis ranges from 0.92 to 1.02, and the x-axis (Wavelength lambda in nm) ranges from 1100 to 1700. Data series are shown for ITU-T G.652 (SMF), ITU-T G.654 (CSF), ITU-T G.653 (DSC-DSF), and ITU-T G.653 (SGC-DSF). Measured data points are shown for step-index (SMF, CSF) and non-step-index (DSC-DSF, SGC-DSF) fibers. Calculated curves are also plotted for each fiber type. The legend indicates: [Measured] for ITU-T G.652 (SMF) [squares], ITU-T G.654 (CSF) [open squares], ITU-T G.653 (DSC-DSF) [circles], and ITU-T G.653 (SGC-DSF) [triangles]. [Calculated] curves are shown for each. DSC = Dual Shape Core, SGC = Segmented Core.](76959415a1298a6f58ea1fff16fb01b6_img.jpg) + +Figure II.2: A plot showing the wavelength dependence of the correction factor k\_n = A\_eff / pi W^2 for various optical fibers. The y-axis ranges from 0.92 to 1.02, and the x-axis (Wavelength lambda in nm) ranges from 1100 to 1700. Data series are shown for ITU-T G.652 (SMF), ITU-T G.654 (CSF), ITU-T G.653 (DSC-DSF), and ITU-T G.653 (SGC-DSF). Measured data points are shown for step-index (SMF, CSF) and non-step-index (DSC-DSF, SGC-DSF) fibers. Calculated curves are also plotted for each fiber type. The legend indicates: [Measured] for ITU-T G.652 (SMF) [squares], ITU-T G.654 (CSF) [open squares], ITU-T G.653 (DSC-DSF) [circles], and ITU-T G.653 (SGC-DSF) [triangles]. [Calculated] curves are shown for each. DSC = Dual Shape Core, SGC = Segmented Core. + +Figure II.2 – Example of calculated and measured wavelength dependence of correction factor $k$ for ITU-T G.652, ITU-T G.653 and ITU-T G.654 fibres + +![Figure II.3: A plot showing the measured wavelength dependence of the effective area A_eff for ITU-T G.655 (NZ-DSF) and ITU-T G.653 (DSF) fibres. The y-axis is A_eff in micrometers squared, ranging from 40 to 110. The x-axis is Wavelength lambda in nm, ranging from 1510 to 1600. Data series are shown for NZ-DSF 1, NZ-DSF 4, NZ-DSF 3, NZ-DSF 2, NZ-DSF 5, DSF 3, DSF 4, DSF 1, and DSF 2. All series show a positive correlation between wavelength and effective area.](9857175bc98d86591d24a161fe615f12_img.jpg) + +Figure II.3: A plot showing the measured wavelength dependence of the effective area A\_eff for ITU-T G.655 (NZ-DSF) and ITU-T G.653 (DSF) fibres. The y-axis is A\_eff in micrometers squared, ranging from 40 to 110. The x-axis is Wavelength lambda in nm, ranging from 1510 to 1600. Data series are shown for NZ-DSF 1, NZ-DSF 4, NZ-DSF 3, NZ-DSF 2, NZ-DSF 5, DSF 3, DSF 4, DSF 1, and DSF 2. All series show a positive correlation between wavelength and effective area. + +Figure II.3 – Example of measured $\lambda$ dependence of $A_{\text{eff}}$ for ITU-T G.653 and ITU-T G.655 fibres + +### II.4 Non-linear coefficient ( $n_2/A_{\text{eff}}$ ) + +For particularly intense fields, the refractive index of optical fibres is dependent on optical intensity inside the fibres, and can be expressed as: + +$$n = n_0 + n_2 I \quad (\text{II-5})$$ + +where $n$ is the refractive index, $n_0$ the linear part of the refractive index, $n_2$ the non-linear refractive index and $I$ the optical intensity inside the fibres. + +The non-linear coefficient is defined as $n_2/A_{\text{eff}}$ . This coefficient plays an important role in evaluating the system performance degradation due to non-linearities when high-power density systems are used. + +Methods for measuring the non-linear coefficient are under study. + +### II.5 Stimulated Brillouin scattering + +In a lightwave communication system using an optical source with a narrow linewidth, significant optical power may be transferred from a forward-propagating signal to a backward-propagating signal when the stimulated Brillouin scattering (SBS) power rating of the optical fibre is exceeded. In SBS, the forward-propagating light is scattered from acoustic phonons. Phase matching (or momentum conservation) dictates that the scattered light preferentially travels in the backward direction. The scattered light is downshifted (or Brillouin-shifted) by approximately 11 GHz at 1 550 nm. + +#### II.5.1 Definitions and measurement overview + +Several possible definitions of SBS power rating are provided as the input power level at which "substantial" backscatter occurs is not unique. This has been recognized previously, see for example [b-Smith 1972] and [b-Kobyakov 2002], where various terms and definitions have been used to quantify the SBS phenomenon (SBS threshold, SBS critical power, etc.). The common concept among these, however, is that the input power at which SBS becomes important is in the regime where the backscatter power begins to increase rapidly. Because of the exponential increase in backscatter power, the range of input powers in this regime is rather narrow [b-Kobyakov 2002], so all definitions give similar (though not identical) results. + +Two SBS power rating definitions are given: one accounting for the rate of increase of the backscatter power, the other relating the backscatter power level to the input power level. These definitions differ in ease of use and visualization, immunity to noise and extraneous reflection, and consistency with theoretical work in the field. + +##### II.5.1.1 Definitions + +- A: The input power at which the rate of increase of the reflected power (with input power) is highest or accelerated maximally. +- Option 1 – The input power where the second derivative of the reflected power $(\text{mW/mW})^2$ is maximum. + - Option 2 – The input power where the second derivative of the transmitted power $(\text{mW/mW})^2$ is minimum. + - Option 3 – The input power where the first derivative of the reflected power $(\text{dBm/dBm})$ is maximum. +- B: The input power at which the reflected power equals 4% of the input power. + +##### II.5.1.2 Measurement overview + +The measurement is conducted by varying the input power into the fibre under test, usually to quite large power levels and usually at equal increments of power as represented by dBm. Using suitable optics at the input end, the reflected power can be measured at the same input powers. The transmitted power can also be measured. In all cases, the reflection from the far end of the fibre must be eliminated to prevent second order SBS interactions. + +#### II.5.2 Apparatus + +Figure II.4 shows a typical measurement set-up that can allow the measurement of input, reflected and transmitted power. The text following indicates some of the requirements. For measurements using only transmitted power, some elements are not required. + +![Figure II.4 – Typical SBS power rating measurement set-up. The diagram shows a light source (1550 nm single-wavelength laser or tunable laser) connected to an Erbium-doped Fibre amplifier (EDFA), which is connected to a Variable optical attenuator (VOA). The VOA output is connected to a polarization control device. The polarization control device output is connected to a two-by-two coupler or optical circulator with one-by-two coupler. The coupler has three output ports: Port A (Detector and power meter), Port B (Detector and power meter), and Port C (Detector and power meter for P_out). Port C is connected to a fibre under test (FUT) via a splice. The FUT is connected to Port A via a splice. The label G.650.2(07)_FII.4 is present in the diagram.](5ee1bbbf85b473f78af9ec8368a4159a_img.jpg) + +``` + +graph LR + LS["Light source: +1550 nm +single-wavelength +laser +or tunable laser"] --> EDFA["Erbium-doped +Fibre amplifier +(EDFA)"] + EDFA --> VOA["Variable optical +attenuator"] + VOA --> PCD["Polarization +control device"] + PCD --> C["Two-by-two coupler or optical +circulator with one-by-two coupler"] + C --> PA["Port A – Detector and power meter"] + C --> PB["Port B – Detector and power meter"] + C --> PC["Port C – Detector +and power meter +for Pout"] + PC --> FUT["FUT"] + FUT -- Splice --> PA + G650207_FII4["G.650.2(07)_FII.4"] + +``` + +Figure II.4 – Typical SBS power rating measurement set-up. The diagram shows a light source (1550 nm single-wavelength laser or tunable laser) connected to an Erbium-doped Fibre amplifier (EDFA), which is connected to a Variable optical attenuator (VOA). The VOA output is connected to a polarization control device. The polarization control device output is connected to a two-by-two coupler or optical circulator with one-by-two coupler. The coupler has three output ports: Port A (Detector and power meter), Port B (Detector and power meter), and Port C (Detector and power meter for P\_out). Port C is connected to a fibre under test (FUT) via a splice. The FUT is connected to Port A via a splice. The label G.650.2(07)\_FII.4 is present in the diagram. + +**Figure II.4 – Typical SBS power rating measurement set-up** + +##### II.5.2.1 Light source + +The light source shall be a narrow-band laser or tunable laser in the 1 550 nm region with the following characteristics: + +- Sufficient power to produce adequate SNR through the erbium-doped fibre amplifier (EDFA). +- Optical frequency stable over the measurement period to within 20 kHz. +- Spectral width (FWHM) less than 200 kHz, with no significant delay line. +- DoP greater than 99%. +- Stable polarization state (SOP) over the duration of the test. This may be verified by monitoring port A. + +##### II.5.2.2 Erbium-doped fibre amplifier (EDFA) + +Depending on the length of the fibre under test, its sensitivity to SBS, and the SBS power rating definition that will be employed in analysis of the data, high powers can be required of the EDFA (15 dBm or more). The EDFA can contribute ASE which can reduce the SBS effects as well as induce depolarization. The SNR of the combination of source laser and EDFA is inversely proportional to the source laser power, but the relationship also depends on the details of the particular EDFA used. The SNR can be calculated from the output of an optical spectrum analyser for various source power levels. The source power shall be sufficiently large that the SNR is in excess of 17 dB. This can be achieved by controlling the EDFA pump power or alternatively by the provision of a bandpass filter. The combination of source power and EDFA shall be stable to within 0.05 dBm over the period of the measurement. + +The EDFA normally includes isolators. If it does not, isolators must be added. Care must be taken that EDFA performance is not degraded by inadequate isolation from large SBS backscatter. + +##### II.5.2.3 Variable optical attenuator (VOA) + +The power of the light that is inserted in the FUT is controlled with the VOA. The VOA should be capable of a range of approximately 20 dB with 0.1 dB increments. The measurement of a reference length removes the need for an absolute calibration of the VOA or its linearity. + +##### **II.5.2.4 Polarization control device** + +The polarization control device, which is optional, allows the power to the FUT to be optimized. It also allows for monitoring for changes in the state of polarization of the source during the course of a measurement. The power optimization results from the possible presence of small amounts of polarization-dependent loss in the other optical elements. Variation in the power monitored at port A gives an indication that the state of polarization of the source has changed. + +##### **II.5.2.5 Two-by-two coupler or optical circulator with one-by-two coupler** + +This device should allow most of the total output power to go into the FUT and a fraction, e.g., 5% or 1%, into port A. This device also allows the measurement of the reflected power at port B. If data analysis is to be performed using definition A then absolute calibration of this device is not required, but should be considered for certain experiments. + +When calibration is completed, the actual measured power values (dBm) are adjusted by constants so that the adjusted powers are representative of the powers going through the pigtail fibre just after the coupler. + +If a circulator with a one-by-two optical coupler is used, there can be fewer problems with light reflected back into the EDFA. + +For either implementation, the linearity of the path from the end of the FUT to port B must be verified to be within 0.04 dB per dB. Non-linearities in excess of this value can place an upper limit on the measurement capability. + +##### **II.5.2.6 Pigtail and splice following the coupler/circulator** + +The pigtail following the coupler should be of sufficient length to allow repeated splices. The splice itself should be either a fusion splice or an angled cleave connector to eliminate reflections. + +##### **II.5.2.7 Fibre termination at port C** + +The fibre end is inserted into the power meter at port C in two situations: + +- a) when the reference length is measured; +- b) when the transmitted power through the full length is measured ( $P_{\text{out}}$ ). + +Measurement of the transmitted power through the full length of the fibre is only required when using definition A, option 2. Certain experiments may involve this measurement even when other definitions are used. When the transmitted power is measured, an angle cleave of approximately 8° is recommended to prevent reflections that can affect the results measured at port B. + +When no full length transmitted power measurements are required, deploy the far end of the FUT around a sufficiently small diameter mandrel or tight pin array to ensure that light is substantially stripped from the fibre before reaching the end. + +Because end reflections can impair SBS power rating measurements using any of the definitions, it is recommended that the Rayleigh backscatter level (reflected power at very low input power) be examined before taking SBS data. ITU-T G.652 fibre of length greater than 20 km generally has a Rayleigh backscatter roughly 33 dB below the input power level. If higher levels than expected of Rayleigh backscatter are measured, the optical termination at the far end of the fibre must be improved. + +The actual power launched into the full length fibre is measured by cutting off a section of approximately 2 m in length after the splice. The range of powers is then scanned again. As a result of the air/glass interface, there is a certain amount of light that is reflected (Fresnel reflection) that depends on the cleave angle of the fibre end. To control the amount of light lost due to Fresnel reflection to a constant 0.14 dB, cleave angles substantially less than 1° are recommended. + +##### **II.5.2.8 Power detectors** + +The power detectors at ports A, B and C should be calibrated according to [b-IEC 61315]. The absolute accuracy of the result using definition A is independent of the absolute accuracies of the detectors at ports A and B. + +In addition to the absolute accuracy, the linearity of the meters, particularly those at ports B and C, should be verified to be within 0.04 dB per dB over the intended range of use. + +##### **II.5.2.9 General** + +The various connections throughout the system should either be fusion splices or angled connectors to avoid reflections. + +The housing for the system should be opaque to avoid the possibility of high-power light escaping. The system should include a fail-safe mechanism or warning to prevent light in excess of 10 dBm (10 mW) from being emitted into the air in the path from the coupler to the FUT (either full length or reference measurement). This can be accomplished with the use of the power detected at port A. + +#### **II.5.3 Procedure** + +This procedure is to be applied to cabled or uncabled fibre. There is some evidence that the manner of deployment may affect the measured results. All measurements should be made at standard room temperature (20°C). + +##### **II.5.3.1 Procedure for reflected power measurement** + +- Set the VOA to a minimum output power. +- Fusion splice the input end of the fibre to the system and terminate the far end with a small diameter mandrel or pin array to eliminate the end reflection. +- Scan the VOA and take the reflected power readings from port B. Power readings from port A may be used to verify consistency of input power through the scan. Return the VOA to minimum power. +- Optionally, remove the termination device from the far end, prepare an 8° endface, and complete the VOA scan again to obtain transmitted power through port C. Return the VOA to minimum power. +- Cut the fibre under test to approximately 2 m from the connection at the source end. Prepare a flat endface to ensure maximum Fresnel reflection. Attach this end to port C. +- Scan the VOA again to obtain the measured input power through port C. Return the VOA to minimum power. +- The power values are normally reported in dBm. Make any adjustments for calibration factors associated with the coupler or circulator. + +##### **II.5.3.2 Procedure for transmitted power only** + +- Set the VOA to a minimum output power. +- Fusion splice the input end of the fibre to the system and terminate the far end to port C using an index-matching connection to minimize the far-end reflection interaction with the SBS process. +- Scan the VOA and take the transmitted power readings from port C. Power readings from port A may be used to verify consistency of input power through the scan. Return the VOA to minimum power. +- Cut the fibre under test to approximately 2 m from the connection at the source end. Prepare a flat endface to ensure maximum Fresnel reflection. Attach this end to port C. + +- Scan the VOA again to obtain the measured input power through port C. Return the VOA to minimum power. +- The power values are normally reported in dBm. + +#### II.5.4 Calculation and interpretation of results + +The data analysis depends on the SBS power rating definition chosen. For definition A, the data must be smoothed by fitting to a high-order polynomial. Definition B requires no fit, but accuracy can be enhanced by a low order polynomial fit (linear interpolation is acceptable). The manner of deployment can affect the measured results. In either case, after the SBS power rating is determined, add 0.14 dB to take into account the Fresnel reflection associated with the end of the fibre. + +##### II.5.4.1 Data analysis using definition A + +The smoothing required by method A can be accomplished by truncating the data and using a high-order polynomial (sixth order or higher) or by using a spline fit (fourth order or higher). For options 1 and 2, the fitting is normally done in dBm and then the results are converted to milliwatt power second derivatives using calculus. Using the high-order polynomial fit requires truncating the data outside the input power region where the reflected power rises rapidly. The spline fit requires substantial data be taken outside of this region. + +Figure II.5 shows typical data for reflected and transmitted power at different input power levels (data taken at 0.1 dB intervals in input power). The symbols and solid lines show the measured and fitting results, respectively. The notations mark the input powers at which the second derivative of the reflected power is at a maximum (option 1), the second derivative of the transmitted power is minimum (option 2) and the first derivative of the reflected power is maximum (option 3). The SBS power rating obtained from definition B is shown for comparison. Figure II.6 shows the second derivative of the reflected power (option 1) with maximal acceleration power denoted by the dash-dotted line. Figure II.7 shows the second derivative of the transmitted power (option 2) with the minimal acceleration power denoted by the dash-dotted line. Figure II.8 shows the first derivative of the reflected power (option 3) with the maximal rate of increase power denoted by the dash-dotted line. In this case, the knot spacing for the fourth order spline fit was 0.66 dB. + +![Figure II.5: Example of reflected and transmitted power. The graph plots Reflected/transmitted power (dBm) on the y-axis (from -40 to 20) against Input power (dBm) on the x-axis (from 0 to 15). Two data series are shown: Reflected (open circles) and Transmitted (open diamonds). The reflected power increases sharply starting around 5 dBm, while the transmitted power remains relatively flat around 0 dBm. Vertical dashed lines indicate various SBS power rating definitions: Def. A (Opt. 3) at ~6.5 dBm, Def. B at ~7.5 dBm, Def. A (Opt. 2) at ~8.5 dBm, and Def. A (Opt. 1) at ~10.5 dBm. A label 'λ = 1550 nm' is present in the bottom right of the plot area. The legend at the bottom left identifies the symbols for Reflected and Transmitted power. A small label 'G.650.2(15)_FII.5' is also present.](810e9c03f216ccb41879979badc63a3f_img.jpg) + +Figure II.5: Example of reflected and transmitted power. The graph plots Reflected/transmitted power (dBm) on the y-axis (from -40 to 20) against Input power (dBm) on the x-axis (from 0 to 15). Two data series are shown: Reflected (open circles) and Transmitted (open diamonds). The reflected power increases sharply starting around 5 dBm, while the transmitted power remains relatively flat around 0 dBm. Vertical dashed lines indicate various SBS power rating definitions: Def. A (Opt. 3) at ~6.5 dBm, Def. B at ~7.5 dBm, Def. A (Opt. 2) at ~8.5 dBm, and Def. A (Opt. 1) at ~10.5 dBm. A label 'λ = 1550 nm' is present in the bottom right of the plot area. The legend at the bottom left identifies the symbols for Reflected and Transmitted power. A small label 'G.650.2(15)\_FII.5' is also present. + +Figure II.5 – Example of reflected and transmitted power + +![Figure II.6: A line graph showing the second derivative of reflected power (mW/mW)² versus input power (dBm) at λ = 1550 nm. The y-axis ranges from 0 to 0.4, and the x-axis ranges from 0 to 15 dBm. A vertical dashed line at approximately 7.5 dBm marks the SBS power rating. The curve shows a sharp peak of about 0.35 at the SBS power rating, followed by several smaller oscillations.](a8523d225a4e279ab9e02f3c28cfa36a_img.jpg) + +Figure II.6: A line graph showing the second derivative of reflected power (mW/mW)² versus input power (dBm) at λ = 1550 nm. The y-axis ranges from 0 to 0.4, and the x-axis ranges from 0 to 15 dBm. A vertical dashed line at approximately 7.5 dBm marks the SBS power rating. The curve shows a sharp peak of about 0.35 at the SBS power rating, followed by several smaller oscillations. + +**Figure II.6 – Example of the second derivative of reflected power in milliwatts (option 1 of definition A)** + +![Figure II.7: A line graph showing the second derivative of transmitted power (mW/mW)² versus input power (dBm) at λ = 1550 nm. The y-axis ranges from -0.4 to 0, and the x-axis ranges from 0 to 15 dBm. A vertical dashed line at approximately 7.5 dBm marks the SBS power rating. The curve shows a sharp negative peak of about -0.35 at the SBS power rating, with oscillations on either side.](fe6af03ab7804980cff28a06241be192_img.jpg) + +Figure II.7: A line graph showing the second derivative of transmitted power (mW/mW)² versus input power (dBm) at λ = 1550 nm. The y-axis ranges from -0.4 to 0, and the x-axis ranges from 0 to 15 dBm. A vertical dashed line at approximately 7.5 dBm marks the SBS power rating. The curve shows a sharp negative peak of about -0.35 at the SBS power rating, with oscillations on either side. + +**Figure II.7 – Example of the second derivative of transmitted power in milliwatts (option 2 of definition A)** + +![Figure II.8: A line graph showing the first derivative of reflected power (dBm/dBm) versus input power (dBm) at λ = 1550 nm. The y-axis ranges from 0 to 12, and the x-axis ranges from 0 to 15 dBm. A vertical dashed line at approximately 7.5 dBm marks the SBS power rating. The curve shows a sharp peak of about 10 at the SBS power rating, followed by a gradual decay towards zero.](b8d13287be9197ff7a1d474afd187b6e_img.jpg) + +Figure II.8: A line graph showing the first derivative of reflected power (dBm/dBm) versus input power (dBm) at λ = 1550 nm. The y-axis ranges from 0 to 12, and the x-axis ranges from 0 to 15 dBm. A vertical dashed line at approximately 7.5 dBm marks the SBS power rating. The curve shows a sharp peak of about 10 at the SBS power rating, followed by a gradual decay towards zero. + +**Figure II.8 – Example of first derivative of reflected power in dBm (option 3 of definition A)** + +##### II.5.4.2 Data analysis using definition B + +Figure II.9 shows application of definition B. The intersection of the reflected power data curve with a line drawn for reflected power of 4% of input power gives the SBS power rating. A comparison of the SBS power rating found from definition B with those of definition A is given in Figure II.5. + +![Figure II.9: A graph showing Reflected/transmitted power (dBm) versus Input power (dBm) at λ = 1550 nm. The graph includes three data series: Reflected (open circles), Transmitted (open diamonds), and 4% of input (dashed line). The Reflected curve starts at approximately -35 dBm at 0 dBm input and increases, crossing the 4% line at approximately 7.5 dBm input, which is labeled as the SBS power rating. The Transmitted curve starts at approximately -5 dBm at 0 dBm input and decreases slightly. A horizontal dashed line labeled 'Rayleigh backscatter level' is shown at approximately -25 dBm. The graph is labeled G.650.2(07)_FII.9.](3c47f29e8e1963959009844c7f3ee025_img.jpg) + +Figure II.9: A graph showing Reflected/transmitted power (dBm) versus Input power (dBm) at λ = 1550 nm. The graph includes three data series: Reflected (open circles), Transmitted (open diamonds), and 4% of input (dashed line). The Reflected curve starts at approximately -35 dBm at 0 dBm input and increases, crossing the 4% line at approximately 7.5 dBm input, which is labeled as the SBS power rating. The Transmitted curve starts at approximately -5 dBm at 0 dBm input and decreases slightly. A horizontal dashed line labeled 'Rayleigh backscatter level' is shown at approximately -25 dBm. The graph is labeled G.650.2(07)\_FII.9. + +**Figure II.9 – Example of 4% of input power (definition B)** + +##### II.5.4.3 Uncertainty in measurement and calculation of SBS power rating + +A properly implemented measurement can allow a repeatability of the SBS power rating within approximately $\pm 0.1$ dB. There can be differences between the different definitions of the order of 0.5 dB. Non-SBS related reflections, due to improper fibre termination, can cause elevated levels of backscatter leading to incorrect results. There are trade-offs between the definitions that place different priorities on certain details of the implementation: + +- Definition A requires fitting a high-order polynomial for differentiation. The choice of algorithm to perform this fit can cause different results (of the order of the measurement repeatability). Measurement noise has a more pronounced effect on the result using this definition than definition B. Best results, particularly for options 1 and 2, are obtained when the input power level is sufficient to see a roll-off in the reflected power (on a dB/dB scale) in the high-power regime. +- Definition B requires an absolute calibration of the splitter or circulator used to capture the reflected light. This definition is less sensitive to noise since a simpler fitting model can be used to interpolate the SBS power rating. Because of the roughly straight-line behaviour of the reflected power near the SBS power rating, estimation can be made of the rating even for data sets where the input power is insufficient to exceed the rating value. + +##### II.5.4.4 Conversion of dBm derivatives to milliwatt derivatives + +Transformations to be used with definition A, options 1 and 2. After the dBm/dBm data are fitted to a polynomial, define $x$ as the input power (dBm) and $f(x)$ as the transmitted or reflected power (dBm). Define $y$ as the input power, in milliwatts, and $g(y)$ as the response, in milliwatts. + +$$\frac{dg(y)}{dy} = \frac{df(x)}{dx} \exp \left[ \frac{\ln 10}{10} (f(x) - x) \right] \quad (\text{II-6})$$ + +$$\frac{d^2g(y)}{dy^2} = \left\{ \frac{df(x)}{dx} \left[ \frac{df(x)}{dx} - 1 \right] + \frac{10}{\ln 10} \frac{d^2f(x)}{dx^2} \right\} \exp \left\{ \frac{\ln 10}{10} [f(x) - 2x] \right\} \quad (\text{II-7})$$ + +The relationship of dBm to milliwatt power is: + +$$dBm = 10 \log_{10}(mW) \quad (II-8)$$ + +##### II.5.4.5 Length normalization + +The SBS power rating value varies with length. For some applications, the value must be reported for the particular length that is measured or used. + +For a comparison of fibres of different lengths, it is recommended that the measured value be normalized to a standardized length ( $L_{STD}$ ). For access networks, a value of 20 km is recommended. + +Length normalization can be done with either of two approaches: one based on the classical formula of Equation II-9 or one which is more exact but more complex (Equation II-13). There is a slight (0.1 dB to 0.2 dB) bias associated with the classical formula. + +###### II.5.4.5.1 Classical formula + +Classically SBS power rating has been described as Equation II-9 [b-Smith, 1972], and the classical formula has been used by many researchers because it makes the explanatory mathematics easier. + +$$P_{CR} = 21 \frac{KA_{eff}}{g_B^{eff} L_{eff}} \left( 1 + \frac{\Delta\nu}{\Delta\nu_B} \right) \text{ (W)} \quad (II-9)$$ + +where: + +$g_B^{eff}$ is the effective Brillouin gain coefficient + +$K$ is a constant between 1 and 2 reflecting the polarization state + +$A_{eff}$ is the effective area + +$L_{eff}$ is the effective length + +$\Delta\nu$ is the source linewidth + +$\Delta\nu_B$ is the Brillouin linewidth ( $\sim 20$ MHz) + +$$L_{eff} = \frac{1 - \exp(-\alpha L)}{\alpha} \quad (II-10)$$ + +$$\alpha = \frac{\ln 10}{10} a \quad (II-11)$$ + +where: + +$L$ is the measured length, in kilometres + +$a$ is the attenuation coefficient, in decibels per kilometre + +Define $SBS_T(L)$ as the measured SBS power rating (dBm) at length $L$ , in kilometres, and $SBS_T(L_{STD})$ as the normalized value for the standard length, $L_{STD}$ . Then from Equation II-9: + +$$SBS_T(L_{STD}) = SBS_T(L) + 10 \log_{10} \left[ \frac{1 - \exp(-\alpha L)}{1 - \exp(-\alpha L_{STD})} \right] \quad (II-12)$$ + +where $\alpha$ is defined as in Equation II-11. + +###### II.5.4.5.2 A more exact formula + +This is extracted from [b-Kobyakov 2002]. A two-stage solution of a non-linear equation is used. The formula is based on Equation II-13: + +$$P_{th}(L) = \frac{\alpha A_{eff}^{ac}}{g_B} \gamma_B(L) \text{ (W)} \quad (II-13)$$ + +where: + +$A_{\text{eff}}^{\text{ac}}$ is the acousto-optic effective area + +$\alpha$ is as defined in Equation II-11 + +$\gamma_{\text{B}}(L)$ is a dimensionless parameter depending on length + +$$g_{\text{B}} = \frac{\tilde{g}_{\text{B}}(\nu)}{K(1 + \Delta\nu/\Delta\nu_{\text{B}})}$$ + +where: + +$K$ , $\Delta\nu$ , and $\Delta\nu_{\text{B}}$ are as defined in Equation II-9 + +$\tilde{g}_{\text{B}}(\nu)$ is the Brillouin gain coefficient, in metres per watt + +The ratio, $\gamma_{\text{B}}(L)/P_{\text{th}}(L)$ , is a constant independent of length + +The dimensionless parameter, $\gamma_{\text{B}}(L)$ is solved using the following non-linear equation and the measured SBS power rating, $P_{\text{th}}$ : + +$$\frac{\exp\{-\gamma_{\text{B}}(L)[1 - \exp(-\alpha L)]\}}{\left[\frac{1}{\gamma_{\text{B}}(L)} + \exp(-\alpha L)\right]} \gamma_{\text{B}}^{3/2}(L) \sqrt{1 - \exp(-\alpha L)} = C' \frac{\gamma_{\text{B}}(L)}{P_{\text{th}}(L)} \quad (\text{II-14})$$ + +where: + +$$C' = \sqrt{\pi k T} \frac{v_{\text{s}}}{v_{\text{a}}} \Delta\nu_{\text{B}} \cong 2.612 \times 10^{-9} \quad (\text{II-15})$$ + +$k$ is the Boltzmann constant ( $1.380\,658 \times 10^{-23}$ ) + +$T$ is the temperature (298°K at room temperature) + +$v_{\text{s}}$ is the signal frequency (193.4 THz for 1 550 nm) + +$v_{\text{a}}$ is the frequency difference between the Stokes wave and the signal (10.8 GHz) + +Given the ratio, $\gamma_{\text{B}}(L)/P_{\text{th}}(L)$ , Equation II-14 is reapplied using $L_{\text{STD}}$ to determine $\gamma_{\text{B}}(L_{\text{STD}})$ . The value of $P_{\text{th}}(L_{\text{STD}})$ follows immediately from the constant ratio. [It must then be converted to dBm for reporting purposes.] + +The value of $C'$ can be varied by plus or minus an order of magnitude from the value presented in Equation II-15. The calculated values of the SBS power rating vary of the order $\pm 0.01$ dB as a result of varying the value of $C'$ in this way. + +##### II.5.4.6 Attenuation normalization + +The SBS power rating value varies with attenuation. For some applications, the value must be reported for the particular attenuation that is measured or used. + +For a comparison of fibres of different attenuation, it is recommended that the measured value be normalized to a standardized attenuation. For a standard attenuation, a value of 0.2 dB/km is recommended. + +Define $SBS_T(\alpha)$ as the measured SBS power rating (dBm) at attenuation $a$ , in decibels per kilometre, and $SBS_T(\alpha_{STD})$ as the normalized value for the standard attenuation, $\alpha_{STD}$ . Then from Equation II-9: + +$$SBS_T(\alpha_{STD}) = SBS_T(\alpha) + 10 \log_{10} \left[ \frac{\alpha_{STD}}{\alpha} \frac{1 - \exp(-\alpha L)}{1 - \exp(-\alpha_{STD} L)} \right] \quad (II-16)$$ + +where $\alpha$ is defined as in Equation II-11. + +#### II.5.5 Documentation + +The following information is reported: + +- wavelength and source linewidth. +- Definition (A, B). +- For definition A, implementation option, details of mathematical fit. +- The SBS power rating value. +- For length normalized values, the normalization length and normalizing formula used. +- For attenuation normalized values, the normalization attenuation. + +### II.6 Other effects + +For a description of other optical non-linear effects (four-wave mixing, modulation instability, self-phase modulation, cross-phase modulation, solitons and stimulated Raman scattering), see Appendix II of [[b-ITU-T G.663](#)]. + +# Appendix III + +## Test methods for effective area ( $A_{\text{eff}}$ ) + +*(This appendix does not form an integral part of this Recommendation.)* + +### III.1 The far-field scan (FFS) technique + +#### III.1.1 General + +The effective area ( $A_{\text{eff}}$ ) of single-mode optical fibres is determined by the far-field scan (FFS) technique. + +#### III.1.2 Test apparatus + +A schematic diagram of the test set-up for far-field scan (FFS) is shown in Figure III.1. + +![Schematic diagram of the far-field scan (FFS) set-up. A tunable laser source is connected to a pigtail, which is joined to a fibre under test. The fibre under test is mounted on a rotation stage. The output of the fibre is detected by a PIN detector. The PIN detector output is connected to a lock-in amplifier, which is connected to a computer. The computer is also connected to the tunable laser source via a reference line. A note indicates that 2R ≈ 40 mm ø (1 turn).](91b12db3c85bbf466ad27eb3665a1b06_img.jpg) + +``` + +graph LR + TLS[Tunable laser source] --> P[Pigtail] + P --> J((Joint)) + J --> FUT[Fibre under test] + FUT --> RS[Rotation stage] + RS --> PD[PIN detecter] + PD --> LA[Lock-in amplifier] + LA --> C[Computer] + C -- Reference --> TLS + +``` + +a) $2R \approx 40 \text{ mm } \phi$ +(1 turn) + +G.650.2(07)\_FIII.1 + +Schematic diagram of the far-field scan (FFS) set-up. A tunable laser source is connected to a pigtail, which is joined to a fibre under test. The fibre under test is mounted on a rotation stage. The output of the fibre is detected by a PIN detector. The PIN detector output is connected to a lock-in amplifier, which is connected to a computer. The computer is also connected to the tunable laser source via a reference line. A note indicates that 2R ≈ 40 mm ø (1 turn). + +**Figure III.1 – Typical arrangement of far-field scan (FFS) set-up** + +III.1.2.1 **Light source** (as in clause 5.1.1.2.1 of [[b-ITU-T G.650.1](#)]). + +III.1.2.2 **Modulation** (as in clause 5.1.1.2.2 of [[b-ITU-T G.650.1](#)]). + +III.1.2.3 **Launching conditions** (as in clause 5.1.1.2.3 of [[b-ITU-T G.650.1](#)]). + +III.1.2.4 **Cladding mode stripper** (as in clause 5.1.1.2.4 of [[b-ITU-T G.650.1](#)]). + +III.1.3.5 **Specimen** (as in clause 5.1.1.2.5 of [[b-ITU-T G.650.1](#)]). + +III.1.2.6 **Scan apparatus** (as in clause 5.1.1.2.6 of [[b-ITU-T G.650.1](#)]). + +III.1.2.7 **Detector** (as in clause 5.1.1.2.7 of [[b-ITU-T G.650.1](#)]). + +III.1.2.8 **Amplifier** (as in clause 5.1.1.2.8 of [[b-ITU-T G.650.1](#)]). + +III.1.2.9 **Data acquisition** (as in clause 5.1.1.2.9 of [[b-ITU-T G.650.1](#)]). + +#### III.1.3 Measurement procedure + +The launch end of the fibre shall be aligned with the launch beam, and the output end of the fibre shall be aligned to the appropriate output device. + +The effective area ( $A_{\text{eff}}$ ) is computed from Equation III-1. + +##### III.1.3.1 Equipment calibration + +For equipment calibration, the magnification of the magnifying optics shall be measured by scanning the length of a specimen whose dimensions are already known with suitable accuracy. This magnification shall be recorded. + +##### III.1.3.2 Calculations + +###### III.1.3.2.1 Equations and figures for effective area ( $A_{\text{eff}}$ ) calculation + +###### 1) *Fold the far-field radiation power data* + +Let $P(\theta_i)$ be the measured power as a function of angular position, $\theta_i$ (radians). The folded power curve, $P_f(\theta_i)$ , for $0 \leq \theta_i \leq \theta_{\max}$ is: + +$$P_f(\theta_i) = \frac{P(\theta_i) + P(-\theta_i)}{2} \quad (\text{III-1})$$ + +###### 2) *Compute the near-field intensity pattern* + +Use an appropriate numerical integration method to compute the integrals of Equation III-1. Equation III-2 is an example. Any other integration method shall be at least as accurate. + +Calculate the near-field values for a range of radii, $r_j$ , values ranging from zero to a value large enough that the computed intensity at the maximum radius is less than 0.01% of the maximum intensity. + +$$I(r_j) = \left\{ \sum_{i=0}^n \sqrt{P_f(\theta_i)} J_0 \left[ \frac{2\pi r_j \sin(\theta_i)}{\lambda} \right] \sin(2\theta_i) \Delta\theta \right\}^2 \quad (\text{III-2})$$ + +where $\Delta\theta = \theta_1 - \theta_0$ and $J_0$ is the Bessel function of order 0. + +NOTE – The square root of the power, $P_f(\theta_i)$ , in Equation III-2 is taken in order to calculate the far-field amplitude from the measured power values. For some very large values of $\theta_i$ , it might be possible that after crossing zero the amplitude must adopt the negative root. One way to avoid this difficulty is to choose $\theta_{\max}$ low enough to ensure that the measured power for all lower angles is greater than the measurement uncertainty. + +###### 3) *Compute the integrals of Equation III-2* + +Use an appropriate numerical integration method to compute the integrals of Equation III-2. Equation III-3 is an example. Any other integration method shall be at least as accurate. + +$$T = \left[ \sum_{j=0}^m I(r_j) r_j \Delta r \right]^2 \quad (\text{III-3})$$ + +$$B = \sum_{j=0}^m I^2(r_j) r_j \Delta r \quad (\text{III-4})$$ + +where $\Delta r = r_1 - r_0$ , and $m$ is the number of positions calculated from Equation III-2. + +###### 4) *Complete the calculation* + +$$A_{\text{eff}} = \frac{2\pi T}{B} \quad (\text{III-5})$$ + +An example of measured far-field power data is shown in Figure III.2. + +![Figure III.2: Example of measured FFP data. A plot showing Intensity (Y-axis, 0 to 1.0) versus Angle [deg.] (X-axis, 0 to 20). The data points, represented by black diamonds, show a rapid decay of intensity from 1.0 at 0 degrees to near zero by 10 degrees, remaining very low up to 20 degrees. The plot is labeled G.650.2(07)_FIII.2.](a74fdbc8b78564b89bc1b262cfd995b6_img.jpg) + +| Angle [deg.] | Intensity | +|--------------|-----------| +| 0 | 1.00 | +| 1 | 0.95 | +| 2 | 0.88 | +| 3 | 0.78 | +| 4 | 0.65 | +| 5 | 0.52 | +| 6 | 0.40 | +| 7 | 0.30 | +| 8 | 0.22 | +| 9 | 0.15 | +| 10 | 0.10 | +| 12 | 0.05 | +| 15 | 0.02 | +| 20 | 0.01 | + +Figure III.2: Example of measured FFP data. A plot showing Intensity (Y-axis, 0 to 1.0) versus Angle [deg.] (X-axis, 0 to 20). The data points, represented by black diamonds, show a rapid decay of intensity from 1.0 at 0 degrees to near zero by 10 degrees, remaining very low up to 20 degrees. The plot is labeled G.650.2(07)\_FIII.2. + +**Figure III.2 – Example of measured FFP data** + +#### III.1.4 Presentation of the results + +The following details shall be presented: + +- a) Test set-up arrangement, dynamic range of the measurement system, processing algorithms, and a description of the aperture assembly used (including the numerical aperture). +- b) Launching conditions. +- c) Wavelength and spectral linewidth FWHM of the source. +- d) Fibre identification and length. +- e) Type of cladding mode stripper. +- f) Type and dimensions of the detector. +- g) Temperature of the sample and environmental conditions (when necessary). +- h) Indication of the accuracy and repeatability. +- i) Effective area ( $A_{\text{eff}}$ ). +- j) Plot of $A_{\text{eff}}(\lambda)$ (if required). + +### III.2 The variable aperture (VA) technique + +#### III.2.1 General + +The effective area ( $A_{\text{eff}}$ ) of SMFs is determined by the variable aperture in the far-field (VA) measurement technique. + +#### III.2.2 Test apparatus + +A schematic diagram of the test set-up for VA technique is shown in Figure III.3. + +![Figure III.3 – Typical arrangement of the variable aperture (VA) technique set-up. The diagram illustrates the optical path starting from a 'Tungsten light source' (Light source) through a 'Monochromator or interference filter(s)' (Input optics), a 'Cladding mode stripper (if required)', and a 'High order mode filter'. This leads into the 'Fibre under test'. The output of the fiber is directed towards an 'Output variable aperture assembly' which is mounted on an 'Output positioner' and includes 'Viewing optics'. The assembly shows a distance D from the fiber end to an aperture of diameter X, subtending a half-angle θ. Following the aperture are 'Output optics' and finally a 'Detector assembly and signal detection electronics'.](7e14467740b2570a44379b347a697921_img.jpg) + +Figure III.3 – Typical arrangement of the variable aperture (VA) technique set-up. The diagram illustrates the optical path starting from a 'Tungsten light source' (Light source) through a 'Monochromator or interference filter(s)' (Input optics), a 'Cladding mode stripper (if required)', and a 'High order mode filter'. This leads into the 'Fibre under test'. The output of the fiber is directed towards an 'Output variable aperture assembly' which is mounted on an 'Output positioner' and includes 'Viewing optics'. The assembly shows a distance D from the fiber end to an aperture of diameter X, subtending a half-angle θ. Following the aperture are 'Output optics' and finally a 'Detector assembly and signal detection electronics'. + +G.650.2(07)\_FIII.3 + +**Figure III.3 – Typical arrangement of the variable aperture (VA) technique set-up** + +**III.2.2.1 Light source** (as in clause 5.1.1.2.1 of [[b-ITU-T G.650.1](#)]). + +**III.2.2.2 Modulation** (as in clause 5.1.1.2.2 of [[b-ITU-T G.650.1](#)]). + +**III.2.2.3 Launching conditions** (as in clause 5.1.1.2.3 of [[b-ITU-T G.650.1](#)]). + +**III.2.2.4 Cladding mode stripper** (as in clause 5.1.1.2.4 of [[b-ITU-T G.650.1](#)]). + +**III.2.2.5 Specimen** (as in clause 5.1.1.2.5 of [[b-ITU-T G.650.1](#)]). + +##### **III.2.2.6 Aperture apparatus** + +A mechanism covering at least 12 apertures spanning the half-angle range of numerical apertures from 0.02 to 0.25 (0.4 for fibres covered by [[b-ITU-T G.653](#)]) should be used. Light transmitted by the aperture is collected and focused onto the detector. + +NOTE – The numerical aperture of the collecting optics must be large enough not to affect the measurement results. + +##### **III.2.2.7 Output variable aperture assembly** + +A device consisting of round transmitting apertures of various sizes (such as an aperture wheel), shall be placed a distance $D$ of at least $100 w^2/\lambda$ from the fibre end, and is used to vary the power collected from the fibre output pattern. Typically 12 to 20 apertures are used and are located about 20–50 mm away from the fibre end. The maximum numerical aperture of the test set shall be equal to 0.40. Means of centring the apertures with respect to the pattern shall be employed to decrease sensitivity to fibre end-angle. + +As part of the equipment set-up (as shown in Figure III.4), carefully measure and record the longitudinal distance $D$ between the fibre output end position and the aperture plane and the diameters $X_i$ of each aperture. Determine the half-angle subtended by each aperture in the wheel and record these $\theta_i$ , ( $i = 1 \dots n$ in order of increasing aperture size) values for future calculation. These values are independent of test wavelength. + +![Diagram of the aperture apparatus set-up. A fibre is shown on the left, with its output end aligned with an aperture. The aperture has a diameter D and is positioned at a distance X from the fibre. The subtended half-angle of the aperture at the fibre is labeled θ. The diagram is labeled G.650.2(07)_FIII.4.](bc6b860289610cf05b09018ab47c90aa_img.jpg) + +Diagram of the aperture apparatus set-up. A fibre is shown on the left, with its output end aligned with an aperture. The aperture has a diameter D and is positioned at a distance X from the fibre. The subtended half-angle of the aperture at the fibre is labeled θ. The diagram is labeled G.650.2(07)\_FIII.4. + +**Figure III.4 – Aperture apparatus set-up** + +**III.2.2.8 Detector** (as in clause 5.1.1.2.7 of [[b-ITU-T G.650.1](#)]). + +**III.2.2.9 Amplifier** (as in clause 5.1.1.2.8 of [[b-ITU-T G.650.1](#)]). + +**III.2.2.10 Data acquisition** (as in clause 5.1.1.2.9 of [[b-ITU-T G.650.1](#)]). + +#### **III.2.3 Measurement procedure** + +The launch end of the fibre shall be aligned with the launch beam, and the output end of the fibre shall be aligned to the appropriate output device. + +The effective area ( $A_{\text{eff}}$ ) is computed from Equations III-6 to III-10. + +#### **III.2.3.1 Equipment calibration** + +For equipment calibration, the magnification of the magnifying optics shall be measured by scanning the length of a specimen whose dimensions are already known with suitable accuracy. This magnification shall be recorded. + +#### **III.2.3.2 Calculations** + +##### **III.2.3.2.1 Equations and figures for effective area ( $A_{\text{eff}}$ ) calculation** + +The variable aperture (VA) technique measures the total normalized power $f(\theta)$ passing through a given aperture as shown in Figure III.3 subtending a far-field half-angle $\theta$ at the fibre. These power values are equivalent to an integration of the normalized far-field power distribution $F^2(\theta)$ . This is represented by Equation III-6. + +$$f(\theta) = \int_0^{\theta} F^2(\theta) \sin(\theta) d\theta \quad (\text{III-6})$$ + +A plot of normalized power transmitted through the apertures as a function of half-angle $\theta$ is shown in Figure III.5. + +![Figure III.5: Plot of measured VA data. The graph shows Normalized power (y-axis, 0 to 1.2) versus Aperture angle (radians) (x-axis, 0 to 0.3). Data points (Power) are shown as blue diamonds, and a smooth curve (Fit) is shown as a solid blue line. The data points start at (0,0) and rise to a plateau of 1.0 around 0.15 radians. A dashed horizontal line is at y=1.0. The plot is labeled G.650.2(07)_FIII.5.](3b6177b1edfdc8c7740f03f346d7838f_img.jpg) + +Figure III.5: Plot of measured VA data. The graph shows Normalized power (y-axis, 0 to 1.2) versus Aperture angle (radians) (x-axis, 0 to 0.3). Data points (Power) are shown as blue diamonds, and a smooth curve (Fit) is shown as a solid blue line. The data points start at (0,0) and rise to a plateau of 1.0 around 0.15 radians. A dashed horizontal line is at y=1.0. The plot is labeled G.650.2(07)\_FIII.5. + +**Figure III.5 – Plot of measured VA data** + +The far-field aperture data, given by Equation III-7, is fitted to a smooth function such as the quartic function: + +$$f(\theta) = A\theta^4 + B\theta^3 + C\theta^2 + D\theta^1 + E \quad (\text{III-7})$$ + +Effective area, $A_{\text{eff}}$ , is calculated from the near-field power distribution $I(r)$ given as a function of radius $r$ . To calculate this, one must first differentiate the integrated power data, $f(\theta)$ , to give the far-field power distribution $F^2(\theta)$ , + +$$F^2(\theta) = \frac{df(\theta)}{d(\theta)} \cdot \frac{1}{\sin \theta} \quad (\text{III-8})$$ + +A plot of this calculated FFP distribution is shown in Figure III.6. + +![Figure III.6: Plot of FFP distribution. The graph shows Calculated power, F^2(theta) (y-axis, 0 to 500) versus theta (radians) (x-axis, 0 to 0.3). Data points (Derivative/sin(theta) = F^2(theta)) are shown as blue diamonds, and a smooth curve is shown as a solid blue line. The data points start at approximately 450 at theta=0 and decay towards zero as theta increases. The plot is labeled G.650.2(07)_FIII.6.](d3c5090abad168738b2dd27087f89fdc_img.jpg) + +Figure III.6: Plot of FFP distribution. The graph shows Calculated power, F^2(theta) (y-axis, 0 to 500) versus theta (radians) (x-axis, 0 to 0.3). Data points (Derivative/sin(theta) = F^2(theta)) are shown as blue diamonds, and a smooth curve is shown as a solid blue line. The data points start at approximately 450 at theta=0 and decay towards zero as theta increases. The plot is labeled G.650.2(07)\_FIII.6. + +**Figure III.6 – Plot of FFP distribution** + +From the far-field power distribution $F^2(\theta)$ , it is then possible to calculate the near-field power distribution $I(r)$ as a function of radius $r$ , using the inverse Hankel transform as follows: + +$$I(r) = \left[ \int_0^\infty \sqrt{F^2(\theta)} J_0\left(\frac{2\pi r \sin(\theta)}{\lambda}\right) \sin(2\theta) d\theta \right]^2 \quad (\text{III-9})$$ + +A plot of this calculated near-field distribution $I(r)$ as a function of radius $r$ is shown in Figure III.7. + +![Figure III.7 – Plot of NFP distribution. The graph shows 'Normalized power' on the y-axis (0 to 1.0) versus 'Radius (μm)' on the x-axis (0 to 20). A curve starts at (0, 1.0) and decays towards zero, reaching near-zero values by 10 μm. The plot is titled 'Near field vs radius' and has a label 'G.650.2(07)_FIII.7' in the bottom right corner.](65678100712a6817696109be76a51f0f_img.jpg) + +Figure III.7 – Plot of NFP distribution. The graph shows 'Normalized power' on the y-axis (0 to 1.0) versus 'Radius (μm)' on the x-axis (0 to 20). A curve starts at (0, 1.0) and decays towards zero, reaching near-zero values by 10 μm. The plot is titled 'Near field vs radius' and has a label 'G.650.2(07)\_FIII.7' in the bottom right corner. + +**Figure III.7 – Plot of NFP distribution** + +Effective area, $A_{\text{eff}}$ , is then calculated from the near-field distribution $I(r)$ using Equation III-10. + +$$A_{\text{eff}} = 2\pi \cdot \frac{\left[ \int_0^\infty I(r) \cdot r dr \right]^2}{\int_0^\infty I(r)^2 \cdot r dr} \quad (\text{III-10})$$ + +#### III.2.4 Presentation of the results + +The following details shall be presented: + +- a) Test set-up arrangement, dynamic range of the measurement system, processing algorithms, and a description of the aperture assembly used (including the numerical aperture). +- b) Launching conditions. +- c) Wavelength and spectral linewidth FWHM of the source. +- d) Fibre identification and length. +- e) Type of cladding mode stripper. +- f) Type and dimensions of the detector. +- g) Temperature of the sample and environmental conditions (when necessary). +- h) Indication of the accuracy and repeatability. +- i) Effective area ( $A_{\text{eff}}$ ). +- j) Plot of $A_{\text{eff}}(\lambda)$ (if required). + +### III.3 The near-field scan (NFS) technique + +#### III.3.1 General + +The effective area ( $A_{\text{eff}}$ ) of single-mode fibres is determined by the near-field scan (NFS) measurement technique. + +#### III.3.2 Test apparatus + +- III.3.2.1 **Light source** (as in clause 5.1.1.2.1 of [[b-ITU-T G.650.1](#)]). +- III.3.2.2 **Modulation** (as in clause 5.1.1.2.2 of [[b-ITU-T G.650.1](#)]). +- III.3.2.3 **Launching conditions** (as in clause 5.1.1.2.3 of [[b-ITU-T G.650.1](#)]). +- III.3.2.4 **Cladding mode stripper** (as in clause 5.1.1.2.4 of [[b-ITU-T G.650.1](#)]). + +**III.3.2.5 Specimen** (as in clause 5.1.1.2.5 of [[b-ITU-T G.650.1](#)]). + +**III.3.2.6 Scan apparatus** (as in clause 5.1.1.2.6 of [[b-ITU-T G.650.1](#)]). + +**III.3.2.7 Detector** (as in clause 5.1.1.2.7 of [[b-ITU-T G.650.1](#)]). + +**III.3.2.8 Amplifier** (as in clause 5.1.1.2.8 of [[b-ITU-T G.650.1](#)]). + +**III.3.2.9 Data acquisition** (as in clause 5.1.1.2.9 of [[b-ITU-T G.650.1](#)]). + +#### **III.3.3 Measurement procedure** + +The launch end of the fibre shall be aligned with the launch beam, and the output end of the fibre shall be aligned to the appropriate output device. + +The effective area ( $A_{\text{eff}}$ ) is computed from Equations III-11 to III-15. + +##### **III.3.3.1 Equipment calibration** + +For equipment calibration, the magnification of the magnifying optics shall be measured by scanning the length of a specimen whose dimensions are already known with suitable accuracy. This magnification shall be recorded. + +##### **III.3.3.2 Calculations** + +###### **III.3.3.2.1 Equations and figures for effective area ( $A_{\text{eff}}$ ) calculation** + +###### 1) *Calculate the centroid* + +For a given cross-section of the NFP that is of maximum extent, with position values given by $r$ and intensity values as $I(r_i)$ , the centroid position, $r_c$ , is given as: + +$$r_c = \frac{\sum r_i I(r_i)}{\sum I(r_i)} \quad (\text{III-11})$$ + +###### 2) *Fold the intensity profile* + +Rank the position and intensity data around the position $r_c$ so that positions above have subscript values greater than zero and positions below have subscript values less than zero. The maximum subscript is given as $n$ . The folded intensity profile is: + +$$I_f(r_i) = [I(r_i) + I(r_{-i})]/2 \quad (\text{III-12})$$ + +###### 3) *Compute the integrals from Equation III-12* + +Use an appropriate numerical integration method to compute the integrals of Equation III-12. The following is an example. Any other integration method shall be at least as accurate. + +$$T = \left[ \sum_0^m I(r_j) r_j \Delta r \right]^2 \quad (\text{III-13})$$ + +$$B = \sum_0^m I^2(r_j) r_j \Delta r \quad (\text{III-14})$$ + +where $\Delta r = r_1 - r_0$ + +###### 4) *Complete the calculation* + +$$A_{\text{eff}} = \frac{2\pi T}{B} \quad (\text{III-15})$$ + +An example of a calculated NFP is shown in Figure III.7. + +#### **III.3.4 Presentation of the results** + +The following details shall be presented: + +- a) Test set-up arrangement, dynamic range of the measurement system, processing algorithms, and a description of the aperture assembly used (including the numerical aperture). +- b) Launching conditions. +- c) Wavelength and spectral linewidth FWHM of the source. +- d) Fibre identification and length. +- e) Type of cladding mode stripper. +- f) Type and dimensions of the detector. +- g) Temperature of the sample and environmental conditions (when necessary). +- h) Indication of the accuracy and repeatability. +- i) Effective area ( $A_{\text{eff}}$ ). +- j) Plot of $A_{\text{eff}}(\lambda)$ (if required). + +# Appendix IV + +## Information on polarization mode dispersion statistics + +(This appendix does not form an integral part of this Recommendation.) + +This appendix is provided to summarize some of the statistical calculations for PMD. [b-IEC/TR 61282-3] documents the calculations and theory more completely. + +NOTE – Other calculation methods are allowed and defined in [b-IEC/TR 61282-3]. The Monte Carlo method is given here because it is the easiest to describe and uses the fewest assumptions. + +### IV.1 Introduction + +PMD is a statistical attribute that, for a given fibre, is defined as the average of measured DGD values across a range of wavelengths. Since the DGD values are random across time and wavelength, there is a theoretical lower limit to achievable reproducibility of the reported PMD value of approximately $\pm 15\%$ . This feature implies that it is not appropriate to select individual fibres or cables to a specification that is tighter than the capability of the process. Such selections are often appropriate for deterministic attributes, such as attenuation, but are not generally appropriate for PMD. This means that a specification on the overall process distribution is most reasonable. + +A second consideration regarding the functionality of PMD is that system impairment at a given time and wavelength is controlled by the DGD value, which varies statistically around the PMD value. If the PMD value for a particular cabled fibre is given, the probability that DGD exceeds a given value can be calculated. It is clear, however, that application of these formulae to a maximum specified value will yield a very inaccurate view of the actual system performance. A statistical specification on PMD, however, can lead to a statistical boundary on the DGD values for the population as a whole. This boundary, defined in terms of probability, leads to a value for use in system design that is approximately 20% lower in DGD value and two orders of magnitude less in probability than the values that would be obtained without a statistical specification. + +From the first consideration, it is desirable to define a single statistical metric for the distribution of the PMD values that are measured on optical fibre cables. The metric, therefore, must incorporate both aspects of process mean and process variability. An upper confidence limit at some probability level is such a metric. + +It is known that the PMD coefficient of a set of concatenated cables can be estimated by the computation of the quadrature average of the PMD coefficients of the individual cables. To give the upper confidence limit metric more meaning in terms of application, the upper bound for a concatenated link of 20 cables is computed. This number of cable sections is smaller than that used in most links, but is large enough to be meaningful in terms of projecting DGD distributions for concatenated links. A probability value of 0.01% is also standardized, partially on the basis of obtaining equivalence with the probability that DGD exceeds a bound, which is required to be very low. The upper confidence limit is named $PMD_Q$ , or link design value and this specification type is known as method 1. + +The probability limit for DGD is set at $6.5 \times 10^{-8}$ based on various system considerations including the presence of other PMD-generating components that may be in the links. [b-IEC/TR 61282-3] describes a method of determining a maximum (defined in terms of probability), so that if a distribution passes the method 1 requirement, the DGD across links comprised of only optical fibre cable will exceed the maximum DGD with a probability less than $6.5 \times 10^{-8}$ . The $DGD_{max}$ value is established for a broad range of distribution shapes. This $DGD_{max}$ method of specifying the PMD distribution of optical fibre cables is known as method 2. Methods of combining the method 2 parameters with those of other optical components are given in [b-IEC/TR 61282-3]. + +Method 1 is a metric that is based on what is measured and is, therefore, somewhat more straightforward for use in trade and commerce as a normative requirement. Method 2 is a means of extrapolating the implications for system design and is, therefore, included as information for system design. + +### IV.2 Data collection + +The calculations are done with PMD values that are representative of a given cable construction and manufacturing time period. Typically at least 100 values are required. The sample is normally taken on different production cables and different fibre locations within the cables. + +The cable distribution can be augmented by measurements of uncabled fibre provided that a stable relationship between uncabled fibre and cable values has been demonstrated for a given construction. One means of such augmentation is to generate several possible cable values from the value of each uncabled fibre. These different values should be selected randomly to represent both the usual relationship and the variability that follows from, for example, measurement reproducibility. Because the range of variations includes reproducibility error, this method of estimating the distribution of cable PMD values can lead to over-estimation of $PMD_Q$ . + +The length of the samples measured could seem to have implications on the method 2 deductions. This has been studied with the following conclusions. The method 2 implications remain valid for any link less than 400 km provided that either: + +- the installed cable sections are less than 10 km; or +- the measured lengths are less than 10 km. + +## IV.3 Calculation of $PMD_Q$ (Monte Carlo) + +The measured PMD coefficient values are represented by $x_i$ , with $i$ ranging from 1 to $N$ , the number of measurements. These values will be used to generate 100 000 concatenated link PMD coefficient values, each computed with the quadrature average of 20 individual cable values that are randomly selected from the sample population. + +NOTE – When $N = 100$ , there are $5.3 \times 10^{20}$ possible link values. + +For each link value computation, select 20 random numbers between 1 and $N$ . Select these values and assign them a subscript, $k$ . The link PMD coefficient, $y$ , is calculated as: + +$$y = \left( \frac{1}{20} \sum_{k=1}^{20} x_k^2 \right)^{1/2} \quad (IV-1)$$ + +Collect the 100 000 values of $y$ into a high density histogram as they are being computed. When this computation is complete, calculate the cumulative probability function from the histogram and determine the PMD value associated with the 99.99% level. Report this value as $PMD_Q$ . If the computed $PMD_Q$ is less than the specified value $[0.5 \text{ ps/km}^{1/2}]$ , the distribution passes method 1. + +## IV.4 Calculation for $DGD_{\max}$ (Monte Carlo) + +This calculation builds on that of the calculation for $PMD_Q$ . In this calculation, a value of $DGD_{\max}$ is predefined (at 25 ps) and a probability of exceeding this value, $P_F$ , is calculated. If the computed probability is less than the specified value ( $6.5 \times 10^{-8}$ ), the distribution passes method 2. + +Before beginning the Monte Carlo, calculate the PMD coefficient limit, $P_{\max}$ , as: + +$$P_{\max} = \frac{DGD_{\max}}{\sqrt{L_{\text{ref}}}} = \frac{25}{20} = 1.25$$ + +For each subsequent pair of 20 cable link concatenation values, $y_j$ and $y_{j+1}$ , a 40-cable concatenation value, $z_j$ , is generated as: + +$$z_j = \left( \frac{y_j^2 + y_{j+1}^2}{2} \right)^{1/2} \quad (\text{IV-2})$$ + +NOTE – This yields 50 000 values of $z_j$ , an adequate number. + +Calculate the probability of exceeding DGDmax on the $j$ th concatenation of 40 links, $p_j$ , as: + +$$p_j = 1 - \int_0^{P_{\max}/z_j} 2 \left( \frac{4}{\pi} \right)^{3/2} \frac{t^2}{\Gamma(3/2)} \exp \left[ -\frac{4}{\pi} t^2 \right] dt \quad (\text{IV-3})$$ + +Microsoft Excel™ defines a function that can compute $p_j$ , GAMMADIST (x, alpha, beta, cumulative). The call to this function should be: + +$$PJ = 1 - \text{GAMMADIST}(4 \times PMAX \times PMAX / (PI() \times ZI \times ZI), 1.5, 1, TRUE) \quad (\text{IV-4})$$ + +The probability of exceeding DGDmax, $P_F$ , is given as: + +$$P_F = \frac{1}{50\,000} \sum_j p_j \quad (\text{IV-5})$$ + +If $P_F$ is less than the specified value, the distribution passes method 2. + +# Bibliography + +- [b-ITU-T G.650.1] Recommendation ITU-T G.650.1 (2010), *Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable*. +- [b-ITU-T G.651.1] Recommendation ITU-T G.651.1 (2007), *Characteristics of a 50/125 µm multimode graded index optical fibre cable for the optical access network*. +- [b-ITU-T G.652] Recommendation ITU-T G.652 (2009), *Characteristics of a single-mode optical fibre and cable*. +- [b-ITU-T G.653] Recommendation ITU-T G.653 (2010), *Characteristics of a dispersion-shifted, single-mode optical fibre and cable*. +- [b-ITU-T G.654] Recommendation ITU-T G.654 (2012), *Characteristics of a cut-off shifted single-mode optical fibre and cable*. +- [b-ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable*. +- [b-ITU-T G.656] Recommendation ITU-T G.656 (2010), *Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport*. +- [b-ITU-T G.657] Recommendation ITU-T G.657 (2012), *Characteristics of a bending-loss insensitive single-mode optical fibre and cable for the access network*. +- [b-ITU-T G.663] Recommendation ITU-T G.663 (2011), *Application-related aspects of optical amplifier devices and subsystems*. +- [b-ITU-T G.666] Recommendation ITU-T G.666 (2011), *Characteristics of polarization mode dispersion compensators and of receivers that compensate for polarization mode dispersion*. +- [b-ITU-T G.671] Recommendation ITU-T G.671 (2012), *Transmission characteristics of optical components and subsystems*. +- [b-IEC/TR 61282-3] IEC/TR 61282-3 (2006), *Fibre optic communication system design guides – Part 3: Calculation of link polarization mode dispersion*. +- [b-IEC/TR 61282-9] IEC/TR 61282-9 (2006), *Fibre optic communication system design guides – Part 9: Guidance on polarization mode dispersion measurements and theory*. +- [b-IEC 61315] IEC 61315 (2005), *Calibration of fibre-optic power meters*. +- [b-Kobyakov 2002] Kobyakov, A., Mehwendale, M., Vasilyev, M., Tsuda, S., Evans, A.F. (2002), Stimulated Brillouin scattering in Raman-pumped fibers: A theoretical approach, *Journal of Lightwave Technology*, **20**, pp. 1635–43. +- [b-Namihira 1994] Namihira, Y. (1994), Relationship between nonlinear effective area and mode field diameter for dispersion shifted fibres, *Electronics Letters*, **30**, pp. 262-264. +- [b-Press 1992] Press, W.H, Flannery, B.P, Teukolsky, S.A, Vetterling, W.T. (1992), *Numerical recipes in C: The art of scientific computing*, 2nd edition, Cambridge University Press. +- [b-Smith, 1972] Smith, R.G. (1972), Optical power handling capacity of low loss optical fibers as determined by stimulated Raman and Brillouin scattering, *Applied Optics*, **11**, pp. 2489–94. + + + + + +## **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.651.1-201811-I_PDF-E/raw.md b/marked/G/T-REC-G.651.1-201811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..93f01ca0f40e928fa359f4b3d7b0f1e75116b6f6 --- /dev/null +++ b/marked/G/T-REC-G.651.1-201811-I_PDF-E/raw.md @@ -0,0 +1,427 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.651.1** + +(11/2018) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Transmission media and optical systems characteristics – +Optical fibre cables + +--- + +**Characteristics of a 50/125 µm multimode +graded index optical fibre cable for the optical +access network** + +Recommendation ITU-T G.651.1 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| General | G.600–G.609 | +| Symmetric cable pairs | G.610–G.619 | +| Land coaxial cable pairs | G.620–G.629 | +| Submarine cables | G.630–G.639 | +| Free space optical systems | G.640–G.649 | +| Optical fibre cables | G.650–G.659 | +| Characteristics of optical components and subsystems | G.660–G.679 | +| Characteristics of optical systems | G.680–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.651.1 + +## Characteristics of a 50/125 µm multimode graded index optical fibre cable for the optical access network + +## Summary + +Recommendation ITU-T G.651.1 recommends a quartz multimode fibre to be used for the access network in specific environments. These environments are multi-tenant building sub-networks in which broadband services have to be delivered to individual apartments. The recommended multimode fibre supports the cost-effective use of 1 Gbit/s Ethernet systems over link lengths up to 550 m, usually based upon the use of 850 nm transceivers. + +The recommended fibre type is an improved version of the well-known 50/125 µm multimode graded-index fibre as recommended in Recommendation ITU-T G.651. Its cost effective use is very common in datacom systems applied in enterprise buildings throughout the world for quite a number of years. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.651.1 | 2007-07-29 | 15 | 11.1002/1000/9181 | +| 1.1 | ITU-T G.651.1 (2007) Amd. 1 | 2008-12-12 | 15 | 11.1002/1000/9670 | +| 2.0 | ITU-T G.651.1 | 2018-11-29 | 15 | 11.1002/1000/13738 | + +## Keywords + +IEC 60793-2-10, IEEE 802.3 Ethernet system standards, ISO/IEC 11801-1, multimode fibre, OMx cabled fibre categories. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-------------------------------------------------------------------------------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Terms and definitions ..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Fibre attributes ..... | 2 | +| 5.1 Cladding diameter ..... | 3 | +| 5.2 Core diameter ..... | 3 | +| 5.3 Core concentricity error..... | 3 | +| 5.4 Non-circularity ..... | 3 | +| 5.5 Numerical aperture ..... | 3 | +| 5.6 Macrobending loss..... | 3 | +| 5.7 Material properties of the fibre..... | 4 | +| 5.8 Refractive index profile ..... | 4 | +| 5.9 Modal bandwidth..... | 4 | +| 5.10 Chromatic dispersion coefficient..... | 4 | +| 6 Cable attributes ..... | 5 | +| 6.1 Attenuation coefficient ..... | 5 | +| 6.2 Modal bandwidth..... | 5 | +| 7 Tables of recommended values ..... | 5 | +| Appendix I – Historical perspective on the evolution of the specification of
Recommendation ITU-T G.651.1 multimode optical fibre cable..... | 7 | +| Bibliography..... | 9 | + +## Introduction + +Worldwide, various technologies for broadband access networks are advancing rapidly to provide the high capacity needed for the increasing customer demands with respect to new services. Apart from the technologies, the network structures and customer densities also vary considerably. A specific segment, which is in the main scope of this Recommendation, is the network in a multi-tenant building. Due to the high connection density and the short distribution cable lengths, cost-effective high capacity optical networks can be designed and installed by making use of 50/125 µm graded-index multimode fibres. Recommendation ITU-T G.651.1 was originally developed based on the previous multimode Recommendation ITU-T G.651. The use of the multimode fibre is currently uncommon for telecom networks owing to the development of the single-mode fibre as described in Appendix I of this Recommendation. On the other hand, the multimode fibres continue to be widely used in premises cabling application such as Ethernet for datacom systems in enterprise buildings, which supports system bit rate of more than 10 Gbit/s. This use is supported by a large series of IEEE system standards. The latest multimode specifications can be found in IEC or ISO/IEC fibre and cable standards, which have higher bandwidth characteristics than Recommendation ITU-T G.651.1. The cross reference table between Recommendation ITU-T G.651.1 and the latest multimode fibre standards is summarized in ITU-T G-series Supplement 40. + +## Recommendation ITU-T G.651.1 + +## Characteristics of a 50/125 µm multimode graded index optical fibre cable for the optical access network + +# 1 Scope + +This Recommendation describes a 50/125 µm graded-index multimode optical fibre cable which is suitable to be used in the 850 nm or 1300 nm region, or alternatively may be used in both wavelength regions simultaneously. + +The geometrical, optical, transmission and mechanical parameters are described below in two categories of attributes: + +- fibre attributes are those attributes that are retained throughout cabling and installation; +- cable attributes that are recommended for cables as they are delivered. + +This Recommendation, and the different performance categories found in Table 1, is intended to support the following related system Recommendations and standards: + +- [b-IEEE 802.3]. + +The characteristics of this fibre, including the definitions of the relevant parameters, their test methods and relevant values, will be refined as studies and experience progress. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [IEC 60793-1-1] IEC 60793-1-1 (2017), *Optical fibres – Part 1-1: Measurement methods and test procedures – General and guidance*. +- [IEC 60793-1-20] IEC 60793-1-20 (2014), *Optical fibres – Part 1-20: Measurement methods and test procedures – Fibre geometry*. +- [IEC 60793-1-30] IEC 60793-1-30 (2010), *Optical fibres – Part 1-30: Measurement methods and test procedures – Fibre proof test*. +- [IEC 60793-1-40] IEC 60793-1-40 (2001), *Optical fibres – Part 1-40: Measurement methods and test procedures – Attenuation*. +- [IEC 60793-1-41] IEC 60793-1-41 (2010), *Optical fibres – Part 1-41: Measurement methods and test procedures – Bandwidth*. +- [IEC 60793-1-42] IEC 60793-1-42 (2013), *Optical fibres – Part 1-42: Measurement methods and test procedures – Chromatic dispersion*. +- [IEC 60793-1-43] IEC 60793-1-43 (2015), *Optical fibres – Part 1-43: Measurement methods and test procedures – Numerical aperture*. +- [IEC 60793-1-47] IEC 60793-1-47 (2017), *Optical fibres – Part 1-47: Measurement methods and test procedures – Macrobending loss*. + +- [IEC 60793-1-49] IEC 60793-1-49 (2018), *Optical fibres – Part 1-49: Measurement methods and test procedures – Differential mode delay.* +- [IEC 60793-2] IEC 60793-2 (2015), *Optical fibres – Part 2: Product specifications – General.* +- [IEC 60793-2-10] IEC 60793-2-10 (2017), *Optical fibres – Part 2-10: Product specifications – Sectional specification for category A1 multimode fibres.* +- [IEC 60794-2] IEC 60794-2 (2017), *Optical fibre cables – Part 2: Indoor cables – Sectional specification.* +- [IEC 60794-2-11] IEC 60794-2-11 (2012), *Optical fibre cables – Part 2-11: Indoor cables – Detailed specification for simplex and duplex cables for use in premises cabling.* +- [IEC 60794-2-21] IEC 60794-2-21 (2012), *Optical fibre cables – Part 2-21: Indoor cables – Detailed specification for multi-fibre optical distribution cables for use in premises cabling.* +- [IEC 60794-2-31] IEC 60794-2-31 (2012), *Optical fibre cables – Part 2-31: Indoor cables – Detailed specification for optical fibre ribbon cables for use in premises cabling.* +- [IEC 60794-3-12] IEC 60794-3-12 (2012), *Optical fibre cables – Part 3-12: Outdoor cables – Detailed specification for duct and directly buried optical telecommunication cables for use in premises cabling.* +- [IEC 61280-4-1] IEC 61280-4-1 (2009), *Fibre-optic communication subsystem test procedures – Part 4-1: Cable plant and links – Multimode fibre-optic cable plant attenuation measurement.* + +# 3 Terms and definitions + +For the purposes of this Recommendation, the definitions and the guidelines to be followed in the measurement to verify the various characteristics are given in the IEC standards series [IEC 60793], [IEC 60794] and [IEC 61280-4-1]. Values shall be rounded to the number of digits given in Table 1 before conformance is evaluated. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +NA Numerical Aperture + +# 5 Fibre attributes + +The characteristics of the fibre providing a minimum essential design framework for fibre manufacture, system design and use are recommended in this clause and in clause 7. Ranges or limits on values are presented in Table 1. In this clause those attributes have been listed only where additional information is helpful. + +The recommended characteristics will not be significantly affected by cable manufacture or installation and therefore apply equally to individual fibres, fibres incorporated into a cable wound on a drum, and fibres in an installed cable. + +## 5.1 Cladding diameter + +The recommended nominal value of the cladding diameter is 125 $\mu\text{m}$ . A tolerance is also specified and shall not exceed the value in clause 7. The cladding diameter deviation from nominal shall not exceed the specified tolerance. For measuring the value of this attribute, reference is made to [IEC 60793-1-20]. + +## 5.2 Core diameter + +The recommended nominal value of the core diameter is 50 $\mu\text{m}$ . A tolerance is also specified and shall not exceed the value in clause 7. The core diameter deviation from nominal shall not exceed the specified tolerance. For measuring the value of this attribute, reference is made to [IEC 60793-1-20]. + +## 5.3 Core concentricity error + +The core concentricity error shall not exceed the value specified in clause 7. For measuring the value of this attribute, reference is made to [IEC 60793-1-20]. + +## 5.4 Non-circularity + +#### 5.4.1 Cladding non-circularity + +The cladding non-circularity shall not exceed the value found in clause 7. For measuring the value of this attribute, reference is made to [IEC 60793-1-20]. + +#### 5.4.2 Core non-circularity + +The core non-circularity shall not exceed the value found in clause 7. For measuring the value of this attribute, reference is made to [IEC 60793-1-20]. + +### 5.5 Numerical aperture + +The numerical aperture (NA) is the sine of the vertex half-angle of the largest cone of rays that can enter or leave the core of an optical fibre, multiplied by the refractive index of the medium in which the vertex of the cone is located. All values measured at 850 nm. The value of the numerical aperture is about 5% lower than the value of the maximum theoretical numerical aperture ( $NA_{\max}$ ) which is derived from a refractive index measurements trace of the core and cladding. + +$$NA_{\max} = (n_1^2 - n_2^2)^{1/2}$$ + +in which $n_1$ is the maximum refractive index of the core and $n_2$ is the refractive index of the innermost homogeneous cladding. For measuring the value of this attribute, reference is made to [IEC 60793-1-43]. + +### 5.6 Macrobending loss + +Macrobending loss varies with bend radius and number of turns about a mandrel with a specified radius but is rather independent of the measuring wavelength. Therefore, testing at one of the wavelengths specified in clause 7 may be sufficient to ensure compliance with this Recommendation. + +When testing multiple macrobends, the mode distribution encountered at a specific macrobend may depend on how many macrobends precede it. For example, the first bend might influence the launch condition at the second bend, and the second bend might influence the launch condition at the third bend, etc. Consequently, the macrobending-added loss at a given bend might be different than the macrobending-added loss at another bend. In particular, the first bend may have the largest influence on following bends. Consequently, the macrobending-added loss produced by multiple bends should not be expressed in the units of "dB/bend" by dividing the total added loss by the number of bends, + +but in dB for the specified number of bends. For measuring the value of this attribute, reference is made to [IEC 60793-1-47] and [IEC 61280-4-1]. + +The macrobending-added loss for the multimode fibre within the scope of this Recommendation is fully determined by its NA value (see Table 1) and the launching conditions at the position in the cable network where a bend is present. + +NOTE – A qualification test may be sufficient to ensure that this requirement is being met. + +### 5.7 Material properties of the fibre + +#### 5.7.1 Fibre materials + +The substances of which the fibres are made should be indicated. + +NOTE – Care may be needed in fusion splicing fibres of different substances. Provisional results indicate that adequate splice loss and strength can be achieved when splicing different high-silica fibres. + +#### 5.7.2 Protective materials + +The physical and chemical properties of the material used for the fibre primary coating and the best way of removing it (if necessary) should be indicated. In the case of single jacketed fibre, similar indications shall be given. + +### 5.8 Refractive index profile + +The refractive index profile of the fibre does not generally need to be known. + +### 5.9 Modal bandwidth + +The modal bandwidth is specified with a minimum value at one or more wavelengths in both the 850 nm and 1300 nm regions. The optical fibre modal bandwidth shall not be lower than the values recommended in clause 7. + +By convention, the modal bandwidth is linearly normalized to 1 km. For measuring the value of this attribute, reference is made to [IEC 60793-1-41]. + +## 5.10 Chromatic dispersion coefficient + +The chromatic dispersion coefficient, $D(\lambda)$ , is specified by putting limits on the parameters of a chromatic dispersion curve that is a function of wavelength in the 1300 nm region. The chromatic dispersion coefficient limit for any wavelength, $\lambda$ , is calculated with the minimum zero-dispersion wavelength, $\lambda_{0min}$ , the maximum zero-dispersion wavelength, $\lambda_{0max}$ , and the maximum zero-dispersion slope coefficient, $S_{0max}$ , according to: + +$$\frac{\lambda S_{0max}}{4} \left[ 1 - \left( \frac{\lambda_{0max}}{\lambda} \right)^4 \right] \leq D(\lambda) \leq \frac{\lambda S_{0max}}{4} \left[ 1 - \left( \frac{\lambda_{0min}}{\lambda} \right)^4 \right]$$ + +The values of $\lambda_{0min}$ , $\lambda_{0max}$ and $S_{0max}$ shall be within the limits indicated in Table 1. For measuring the value of this attribute, reference is made to [IEC 60793-1-42]. + +NOTE 1 – The worst-case chromatic dispersion coefficient at 850 nm as derived from the recommended values in clause 7 is $-104 \text{ ps/nm} \cdot \text{km}$ (e.g., $S_0 = 0.09375 \text{ ps/nm}^2 \cdot \text{km}$ at $\lambda_0 = 1340 \text{ nm}$ or $S_0 = 0.10125 \text{ ps/nm}^2 \cdot \text{km}$ at $\lambda_0 = 1320 \text{ nm}$ ). + +NOTE 2 – Specification compliance of chromatic dispersion can be assured by compliance to the numerical aperture specification. + +# 6 Cable attributes + +Since the geometrical and optical characteristics of fibres given in clause 5 are barely affected by the cabling process, this clause gives recommendations mainly relevant to transmission characteristics of cabled fibres. + +Environmental and test conditions are paramount and are described in the guidelines for test methods. + +## 6.1 Attenuation coefficient + +The attenuation coefficient is specified with a maximum value at one or more wavelengths in both the 850 nm and 1300 nm regions. The optical fibre cable attenuation coefficient values shall not exceed the values recommended in clause 7. For measuring the value of this attribute, reference is made to [IEC 60793-1-40]. + +## 6.2 Modal bandwidth + +The cable requirement for modal bandwidth is that the cable shall include fibre that complies with the fibre modal bandwidth-length product as recommended in clause 7. + +# 7 Tables of recommended values + +Table 1 summarizes the recommended values for the 50/125 µm graded-index multimode fibres that satisfy the objectives of this Recommendation. They support the application in Ethernet-based systems with transmission speeds ranging up to 1 Gbit/s, either in the 850 nm or in the 1300 nm wavelength window. For the 1 Gbit/s systems, the link length is 550 m both at 850 nm (1000BASE-SX) and at 1300 nm (1000BASE-LX). + +The modal bandwidth-length product requirements as stated in Table 1 have been coded as "OM2" in [b-ISO/IEC 11801] and have also been normatively defined in the optical fibre cable standards listed in clause 2. The use of any other "OM-x" grade multimode fibre, with higher bandwidth than that of "OM2", satisfies the requirements of this Recommendation. + +Longer link lengths up to 1000 or 2000 m at either one of the two or both wavelength regions can be supported if the customer and the manufacturer agree on improved attribute values, modal bandwidth in particular. + +NOTE 1 – The cross-reference table for multimode fibres developed in ITU-T, IEC, ISO/IEC can be found in Appendix V of [b-ITU-T G-Sup.40]. + +NOTE 2 – ITU-T G.651.1 was initially specified in compliance with OM2 category fibre in the 2002 version of [b-ISO/IEC 11801]. The current specification of ITU-T G.651.1 is compatible with OM2 category fibre in the 2017 version of [b-ISO/IEC 11801-1], in particular in Annex F, Table F.1 – Grandfathered OM1, OM2 and OS1 specifications. + +**Table 1 – Attributes** + +| Fibre attributes | | | | +|------------------------------------------------------|---------------------------------------------------|-----------------------------------------------------|-------------------------| +| Attribute | Detail | Value | Unit | +| Cladding diameter | Nominal | 125 | μm | +| | Tolerance | ±1 | μm | +| Core diameter | Nominal | 50 | μm | +| | Tolerance | ±2.5 | μm | +| Core-cladding concentricity error | Maximum | 2 | μm | +| Core non-circularity | Maximum | 6 | % | +| Cladding non-circularity | Maximum | 2 | % | +| Numerical aperture | Nominal | 0.20 | | +| | Tolerance | ±0.015 | | +| Macrobend loss

(Notes 1 and 2) | Radius | 15 | mm | +| | Number of turns | 2 | | +| | Maximum at 850 nm | 1.0 | dB | +| | Maximum at 1300 nm | 1.0 | dB | +| Proof stress | Minimum | 0.69 | GPa | +| Modal bandwidth-length product for overfilled launch | Minimum at 850 nm | 500 | MHz · km | +| | Minimum at 1300 nm | 500 | MHz · km | +| Chromatic dispersion coefficient

(Note 3) | $\lambda_{0min}$ | 1295 | nm | +| | $\lambda_{0max}$ | 1340 | nm | +| | $S_{0max}$ for $1295 \leq \lambda_0 \leq 1310$ nm | $\leq 0.105$ | ps/nm 2 · km | +| | $S_{0max}$ for $1310 \leq \lambda_0 \leq 1340$ nm | $\leq 375 \times (1590 - \lambda_0) \times 10^{-6}$ | ps/nm 2 · km | +| Cable attributes | | | | +| Attribute | Detail | Value | Unit | +| Attenuation coefficient | Maximum at 850 nm | 3.5 | dB/km | +| | Maximum at 1300 nm | 1.0 | dB/km | + +NOTE 1 – In case of use of the multimode fibre outside the scope of this Recommendation, other macrobending loss values may be valid as specified in [IEC 60793-2-10]. + +NOTE 2 – For testing the macrobending loss value, the launching conditions as specified for the attenuation measurement in [IEC 61280-4-1] shall be used. + +NOTE 3 – The worst-case chromatic dispersion coefficient at 850 nm (e.g., $S_0 = 0.09375$ ps/nm2 · km at $\lambda_0 = 1340$ nm or $S_0 = 0.10125$ ps/nm2 · km at $\lambda_0 = 1320$ nm) is $-104$ ps/nm · km. + +# Appendix I + +## Historical perspective on the evolution of the specification of Recommendation ITU-T G.651.1 multimode optical fibre cable + +(This appendix does not form an integral part of this Recommendation.) + +[b-ITU-T G.651], originally published in 1980, covered the geometrical and transmissive properties of multimode fibres having a 50 $\mu\text{m}$ nominal core diameter and a 125 $\mu\text{m}$ nominal cladding diameter. Test methods and the meanings of the terms used were in the text. + +That Recommendation, which had not been significantly changed from the original in the four subsequent editions through 1998, was developed during the infancy of optical fibre solutions for publicly switched networks. At that time (pre-1984), these fibres were considered as the only practical solution for transmission distances in the 10's of kilometres and bit-rates of up to 40 Mbit/s. Single-mode ITU-T G.652 fibres, which became available shortly after the publication of [b-ITU-T G.651], have almost completely replaced multimode fibres in the public switched networks. + +Currently, multimode fibres continue to be widely used in premises cabling applications such as Ethernet in lengths from 300 to 2000 m, depending on bit rate. With a change in the applications, the multimode fibre definitions, requirements, and measurements evolved away from the original [b-ITU-T G.651] in some ways and were maintained or improved in others. + +The transmission characteristics from this Recommendation have also been moved to the modern equivalent, Recommendation ITU-T G.651.1. A complete documentation for the modern requirements is found in [IEC 60793-2-10]. + +The contents of [b-ITU-T G.651] included the early parameter definitions for glass geometry, numerical aperture, attenuation and baseband response (the combination of modal bandwidth and chromatic dispersion). Some limits on these parameters were also given. Formulas for the attenuation and bandwidth of installed links that comprised of concatenations of cables were given. Measurement methods for the parameters were also described. + +Some differences between [b-ITU-T G.651] and the modern requirements include: + +- i) the core diameter is defined in terms of the near field profile, rather than the refractive index profile; +- ii) parameters such as core/cladding tolerance field and intrinsic quality factor are no longer used; +- iii) the proof test stress is now twice what it was; +- iv) bandwidth limits were then 200 MHz $\cdot$ km, whereas now limits can be as large as 2000 MHz $\cdot$ km. + +With the acceptance of more modern and more tightly specified Recommendation ITU-T G.651.1 in 2007, the old [b-ITU-T G.651] was felt to be obsolete, and therefore was withdrawn in February 2008. This appendix indicates some background information about the old [b-ITU-T G.651]. + +**Table I.1 – Fibre characteristics of the withdrawn Recommendation ITU-T G.651** + +| Attribute | Detail | Value | Unit | +|------------------------------------------------------|--------------------|--------------|--------------| +| Cladding diameter | Nominal | 125 | μm | +| | Tolerance | ±3 | μm | +| Core diameter | Nominal | 50 | μm | +| | Tolerance | ± 3 | μm | +| Core-cladding concentricity error | Maximum | 6 | % | +| Core non-circularity | Maximum | 6 | % | +| Cladding non-circularity | Maximum | 2 | % | +| Numerical aperture | Nominal | 0.20 or 0.23 | | +| | Tolerance | ±0.02 | | +| Proof stress | Minimum | 0.35 | GPa | +| Modal bandwidth-length product for overfilled launch | Minimum at 850 nm | 200 | MHz · km | +| | Minimum at 1300 nm | 200 | MHz · km | +| Chromatic dispersion coefficient | Typical at 850 nm | ≤ 120 | ps/(nm · km) | +| | Typical at 1300 nm | ≤ 6 | ps/(nm · km) | +| Cable attributes | | | | +| Attribute | Detail | Value | Unit | +| Attenuation coefficient | Maximum at 850 nm | 4 | dB/km | +| | Maximum at 1300 nm | 2 | dB/km | + +## Bibliography + +- [b-ITU-T G.651] Recommendation ITU-T G.651(1998), *Characteristics of a 50/125 µm multimode graded index optical fibre cable*. +<> +- [b-ITU-T G.983.x] ITU-T G.983.x series of Recommendations (2001-2005), *Broadband optical access systems based on Passive Optical Networks (PON)*. +- [b-ITU-T G.984.x] ITU-T G.984.x series of Recommendations (2003-2007), *Gigabit-capable Passive Optical Networks (G-PON)*. +- [b-ITU-T L.67] Recommendation ITU-T L.67 (2006), *Small count optical fibre cables for indoor applications*. +- [b-ITU-T G-Sup.40] ITU-T G-series Supplement 40 (2018), *Optical fibre and cable Recommendations and standards guideline*. +- [b-ITU-T ANT] ITU-T SG 15 WP 1; *ANT standards overview*. +<[itu.int/en/ITU-T/studygroups/2013-2016/15/Documents/Overviews\\_WorkPlans/ANT-Standards-Overview-V29.docx](http://itu.int/en/ITU-T/studygroups/2013-2016/15/Documents/Overviews_WorkPlans/ANT-Standards-Overview-V29.docx)> +- [b-IEC 62048] IEC 62048 (2002), *Optical fibres – Reliability – Power law theory*. +- [b-IEEE 802.3] IEEE std. 802.3 (2005), *Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications*. +- [b-ISO/IEC 11801] ISO/IEC 11801:2002, *Information technology – Generic cabling for customer premises*. +- [b-ISO/IEC 11801-1] ISO/IEC 11801-1:2017, *Information technology – Generic cabling for customer premises – Part 1: General requirements*. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.656-201007-I_PDF-E/1d529a819ad929684331c55eed6673bb_img.jpg b/marked/G/T-REC-G.656-201007-I_PDF-E/1d529a819ad929684331c55eed6673bb_img.jpg new file mode 100644 index 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b/marked/G/T-REC-G.724-198811-I_PDF-E/raw.md @@ -0,0 +1,231 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.724** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**GENERAL ASPECTS OF DIGITAL TRANSMISSION +SYSTEMS** + +**TERMINAL EQUIPMENTS** + +--- + +**CHARACTERISTICS OF A 48-CHANNEL +LOW BIT RATE ENCODING PRIMARY +MULTIPLEX OPERATING AT 1544 kbit/s** + +**ITU-T Recommendation G.724** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +- 1 ITU-T Recommendation G.724 was published in Fascicle III.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **CHARACTERISTICS OF A 48-CHANNEL LOW BIT RATE ENCODING PRIMARY MULTIPLEX OPERATING AT 1544 kbit/s** + +(Melbourne, 1988) + +## **1 General** + +### **1.1 Fundamental characteristics** + +The 48-channel primary multiplexer provides conversion between 48 voice-frequency channels and one 1544 kbit/s ADPCM stream. In the 1544 kbit/s stream, the voice-frequency signals are coded according to the PCM encoding law defined in Recommendation G.711 and the ADPCM encoding law defined in Recommendation G.721. In addition, it may be arranged to provide limited 64 kbit/s unrestricted channel transfer capacity for baseband digital channel. + +Figure 1/G.724 represents the nomenclature used. + +![Diagram of a 48-channel low bit rate encoding primary multiplex. A central rectangular box represents the multiplexer. On the left, multiple input lines are labeled 'A', with vertical dots between them indicating multiple channels. Below these inputs is the text 'Voice-frequency and baseband digital data channels, 48 maximum'. On the right, two output lines are labeled 'Z', each followed by '1544 kbit/s'. Below these outputs is the text '48 channels maximum; ADPCM channels coded at 32 kbit/s'. A small label 'T1810070-89' is located near the bottom right of the box.](7a1dee155822446f7828dcb055c465c3_img.jpg) + +Diagram of a 48-channel low bit rate encoding primary multiplex. A central rectangular box represents the multiplexer. On the left, multiple input lines are labeled 'A', with vertical dots between them indicating multiple channels. Below these inputs is the text 'Voice-frequency and baseband digital data channels, 48 maximum'. On the right, two output lines are labeled 'Z', each followed by '1544 kbit/s'. Below these outputs is the text '48 channels maximum; ADPCM channels coded at 32 kbit/s'. A small label 'T1810070-89' is located near the bottom right of the box. + +FIGURE 1/G.724 +**48-channel low bit rate encoding primary multiplex** + +The 1544 kbit/s stream associated with port Z can be partitioned into four independent 384 kbit/s entities defined as time-slot groupings. Each 384 kbit/s time-slot grouping consists of twelve 32 kbit/s time slots which can be used to transport up to 12 voice-frequency channels or 11 voice-frequency channels plus their channel associated a-b-c-d signalling information. Therefore, the 1544 kbit/s stream associated with port Z will have a maximum channel capacity of between 44 and 48 voice-frequency channels. + +*Note 1* - Administrations should take into account the guidance given in Recommendation G.721 concerning the use and transmission performance of 32 kbit/s ADPCM. + +*Note 2* - It should be noted that the primary multiplex equipment described in this Recommendation has a limited capability of transparently transporting 64 kbit/s data channel, and this should be taken into account in the planning of networks which are likely to evolve into an ISDN (see § 4.2). + +### **1.2 Timing signal** + +It should be possible to derive the transmit timing signal from an incoming digital signal or from an external source. + +## 2 Characteristics of port A interfaces + +Analogue: Refer to § 3 of Recommendation G.712 and § 3 of Recommendation G.713. + +Digital: Refer to § 1 of Recommendation G.703. + +## 3 End-to-end analogue transmission performance + +For further study. + +## 4 Characteristics of a 1544 kbit/s signal organized in 32 kbit/s and/or 64 kbit/s timeslots (port Z) + +### 4.1 *Interface Z* + +The electrical characteristics of the 1544 kbit/s interface are in accordance with § 2 of Recommendation G.703. + +### 4.2 *Frame structure* + +#### 4.2.1 *Frame structure at 1544 kbit/s* + +Refer to § 3.2.1 of Recommendation G.704 for frame structure and use of derived channel time slots. + +#### 4.2.2 *Frame structure at 384 kbit/s* + +Refer to § 3.2.3 of Recommendation G.704 for frame structure at 348 kbit/s. + +### 4.3 *Loss and recovery of frame and multiframe alignment* + +#### 4.3.1 *Loss and recovery of 1544 kbit/s frame and multiframe alignment* + +The criteria for loss and recovery of the frame alignment and multiframe alignment signal for port Z are in accordance with § 2.1 of Recommendation G.706 for the 24-frame multiframe and for the 12-frame multiframe. + +#### 4.3.2 *Loss and recovery of signalling grouping channel multiframe alignment* + +The criteria for loss and recovery of the signalling grouping channel multiframe alignment signal are in accordance with § 3.2.6 of Recommendation G.704. + +### 4.4 *Signalling* + +Refer to § 3.2.4 of Recommendation G.704 for signalling in the 384 kbit/s stream. + +## 5 Other characteristics of the low bit rate encoding primary multiplex equipment + +### 5.1 *48-channel frame structure* + +In the case where streams A are each carrying 48 voice-frequency signals and no channel associated signalling information is present, stream Z will transmit the full complement of 48 channels. When channel associated signalling is present, this is conveyed in the last 4-bit time slot of each time-slot grouping. Table 1/G.724 shows the correspondence between the VF channels and the 32 kbit/s ADPCM channels in stream Z. + +### 5.2 *Direct time-slot transfer* + +It should be possible to select and pass voice-frequency and baseband digital A streams through the Z stream at 64 kbit/s. Furthermore, it should be possible to pass through at least one such 64 kbit/s channel in each time-slot grouping in stream Z. + +TABLE 1/G.724 + +#### **Organization of the 1544 kbit/s frame for up to 48 channels at 32 kbit/s in stream Z** + +| | | | | | | | | | | | | | | +|--------------------------------------|----|----|----|----|----|----|----|----|----|-----|-----|------------|----------------------| +| 4-bit time slot of stream Z | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | Time-slot grouping 1 | +| Voice-frequency channels of stream A | 1A | 2A | 3A | 4A | 5A | 6A | 7A | 8A | 9A | 10A | 11A | 12A or SGC | | + +| | | | | | | | | | | | | | | +|--------------------------------------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|------------|----------------------| +| 4-bit time slot of stream Z | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | Time-slot grouping 2 | +| Voice-frequency channels of stream A | 13A | 14A | 15A | 16A | 17A | 18A | 19A | 20A | 21A | 22A | 23A | 24A or SGC | | + +| | | | | | | | | | | | | | | +|--------------------------------------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|------------|----------------------| +| 4-bit time slot of stream Z | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | Time-slot grouping 3 | +| Voice-frequency channels of stream A | 25A | 26A | 27A | 28A | 29A | 30A | 31A | 32A | 33A | 34A | 35A | 36A or SGC | | + +| | | | | | | | | | | | | | | +|--------------------------------------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|------------|----------------------| +| 4-bit time slot of stream Z | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | Time-slot grouping 4 | +| Voice-frequency channels of stream A | 37A | 38A | 39A | 40A | 41A | 42A | 43A | 44A | 45A | 46A | 47A | 48A or SGC | | + +SGC Signalling grouping channel. + +*Note* - Selection of the time-slot grouping format to include the signalling grouping channel is made on a per-time-slot grouping basis, independent of the other time-slot groupings. + +### 5.3 *Signalling grouping channel alarm indications* + +A time-slot grouping alarm is declared when the signalling grouping channel multiframe alignment signal is lost for an interval of between 2 to 3 seconds. + +When signalling grouping channel multiframe alignment is lost (as per § 3.2.6 of Recommendation G.704), updating of the channel-associated signalling bits on the receive side of stream A will be disabled. + +The time-slot grouping alarm is released when signalling grouping channel multiframe alignment has been re-acquired for an interval of between 10 to 20 seconds. + +When signalling grouping channel multiframe alignment is declared (as per § 3.2.6 of Recommendation G.704), updating of the channel-associated signalling bits on the receive side of stream A will be enabled. + +On the send side, $M_1$ is set to 1 to transmit a time-slot grouping alarm to the remote end when the near end is in time-slot grouping alarm. On the receive side, a remote time-slot grouping alarm is declared when $M_1$ , $M_2$ or $M_3$ has been set for 335 to 1000 milliseconds. Remote time-slot grouping alarm is released when $M_1$ , $M_2$ and $M_3$ has been reset for 20 to 1000 milliseconds. + +### 5.4 *Fault conditions and consequent actions* + +#### 5.4.1 *1544 kbit/s fault conditions associated with stream Z* + +A summary of the 1544 kbit/s fault conditions associated with the receive side of stream Z and the consequent actions are listed in Table 2/G.724. + +The primary multiplex shall detect the following 1544 kbit/s fault conditions associated with stream Z: + +- i) loss of incoming signals at 1544 kbit/s; +- ii) loss of 1544 kbit/s frame alignment; +- iii) 1544 kbit/s alarm indication signal (AIS) received; +- iv) 1544 kbit/s alarm indication received from the remote end. + +#### 5.4.2 *Consequent actions associated with stream Z* + +Upon detection of 1544 kbit/s fault conditions in stream Z, appropriate actions should be taken which are in accordance with § 4.2 of Recommendation G.733. In addition, the following consequent actions should be taken as indicated in Table 2/G.724: + +- i) declare a 1544 kbit/s alarm on the receive side of port Z; +- ii) send a 1544 kbit/s alarm indication to the remote end on the send side of port Z in accordance with § 4.2.4 of Recommendation G.733; +- iii) declare a remote 1544 kbit/s alarm on the receive side of port Z. + +#### 5.4.3 *Fault conditions associated with the signalling grouping channel* + +A summary of the signalling grouping channel fault conditions associated with the receive side of stream Z and + +the consequent actions are listed In Table 3/G.724. + +The transcoder shall detect the following signalling grouping channel fault conditions associated with stream Z. + +- i) loss of signalling grouping channel multiframe alignment on a single time-slot grouping; +- ii) remote time-slot grouping alarm indication ( $M_1$ ) receive from the remote end on a single time-slot grouping; +- iii) signalling grouping channel AIS ( $M_2$ ) receive from the remote end on a single time-slot grouping; +- iv) Remote signalling grouping channel AIS ( $M_3$ ) received from the remote end on a single time-slot grouping. + +TABLE 2/G.724 + +##### **1544 kbit/s fault conditions associated with stream Z and consequent actions** + +| Fault conditions | Consequent actions | Declare 1544 kbit/s alarm on Z
(i) | Send 1544 kbit/s alarm indication to remote end on Z
(ii) | Declare remote 1544 kbit/s alarm on Z
(iii) | +|---------------------------------------------------------------|--------------------|---------------------------------------|--------------------------------------------------------------|------------------------------------------------| +| Loss of incoming signal at 1544 kbit/s
(i) | | Yes | Yes | | +| Loss of 1544 kbit/s frame alignment
(ii) | | Yes | Yes | | +| 1544 kbit/s AIS received
(iii) | | Yes | Yes | | +| 1544 kbit/s alarm indication received from remote end
(iv) | | | | Yes | + +#### **5.4.4 Consequent actions associated with the signalling grouping channel** + +Upon detection of signalling grouping channel fault conditions in stream Z, the following consequent actions shall be taken as indicated in Table 3/G.724: + +- i) declare a time-slot grouping alarm on the associated time-slot grouping; +- ii) send a time-slot grouping alarm indication to the remote end by forcing the $M_1$ bit within the affected signalling grouping channel to 1; +- iii) condition the data in the affected channels on the receive side of streams A to provide a signal that is compatible with downstream equipment; +- iv) condition the channel-associated signalling in affected channels on the receive side of stream A to provide a signalling that is compatible with downstream equipment; + +- v) declare a remote time-slot grouping alarm condition on the associated time-slot grouping to indicate the reception of a remote time-slot grouping alarm indication to the $M_1$ bit of the affected signalling grouping channel; +- vi) declare a signalling grouping channel AIS condition on the associated time-slot grouping to indicate the reception of a signalling grouping channel AIS indication in the $M_2$ bit of the affected signalling grouping channel; +- vii) declare a remote signalling grouping channel AIS condition on the associated time-slot grouping to indicate the reception of a remote signalling grouping channel AIS indication in the $M_3$ bit of the affected signalling grouping channel. + +### 5.5 *Jitter* + +For further study. + +**TABLE 3/G.724** +**Signalling grouping channel fault conditions associated with stream Z and consequent action** + +| Consequent actions | Declare time-slot grouping alarm | Send time-slot grouping alarm indication to remote end | Condition affected channels on A | Condition signalling in affected channels on A | Declare remote time-slot grouping alarm | Declare signalling grouping channel AIS | Declare remote signalling grouping channel AIS | +|---------------------------------------------------------------------------------------------|----------------------------------|--------------------------------------------------------|----------------------------------|------------------------------------------------|-----------------------------------------|-----------------------------------------|------------------------------------------------| +| Fault conditions | (i) | (ii) | (iii) | (iv) | (v) | (vi) | (vii) | +| Loss of signalling grouping channel multiframe alignment (single time-slot grouping)
(i) | Yes | Yes | Yes | Yes | | | | +| Remote time-slot grouping alarm indication received (single time-slot grouping)
(ii) | | | Yes | Yes | Yes | | | +| Signalling grouping channel AIS received (single time-slot grouping)
(iii) | | | Yes | Yes | | Yes | | +| Remote signalling grouping channel AIS received (single time-slot grouping)
(iv) | | | Yes | Yes | | | Yes | \ No newline at end of file diff --git a/marked/G/T-REC-G.731-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.731-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.731-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.731-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.731-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..4a7fddd288d650613e78863b9ee1c7f5bc98af39 --- /dev/null +++ b/marked/G/T-REC-G.731-198811-I_PDF-E/raw.md @@ -0,0 +1,54 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.731** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**GENERAL ASPECTS OF DIGITAL TRANSMISSION +SYSTEMS** + +**TERMINAL EQUIPMENTS** + +--- + +**PRIMARY PCM MULTIPLEX EQUIPMENT FOR +VOICE FREQUENCIES** + +**ITU-T Recommendation G.731** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +- 1 ITU-T Recommendation G.731 was published in Fascicle III.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## **Recommendation G.731** + +## **PRIMARY PCM MULTIPLEX EQUIPMENT FOR VOICE FREQUENCIES** + +*(Geneva, 1972; further amended)* + +The CCITT, + +*considering* + +that pulse code modulation (PCM) multiplex equipments are already used in various countries, in particular to provide a large number of short-distance telephone circuits on certain pairs in existing cables, and in order to minimize the number of different PCM multiplex equipments providing circuits which may be used in international connections, + +*recommends* + +that Administrations concerned should make their choice between the 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TELECOMMUNICATION UNION + +**ITU-T** + +**G.761** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**GENERAL ASPECTS OF DIGITAL TRANSMISSION +SYSTEMS** + +**TERMINAL EQUIPMENTS** + +--- + +**GENERAL CHARACTERISTICS +OF A 60-CHANNEL TRANSCODER +EQUIPMENT** + +**ITU-T Recommendation G.761** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.761 was published in Fascicle III.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **GENERAL CHARACTERISTICS OF A 60-CHANNEL TRANSCODER EQUIPMENT** + +*(Malaga-Torremolinos, 1984; amended at Melbourne, 1988)* + +## **1 General** + +The 60-channel transcoder implements a conversion between two 30-channel 2048 kbit/s PCM streams and one 60-channel 2048 kbit/s ADPCM stream. In the 30-channel 2048 kbit/s streams, the telephone signals are coded using 64 kbit/s A-law PCM as specified in Recommendation G.711. In the 60-channel 2048 kbit/s stream, the telephone signals are coded using 32 kbit/s ADPCM as specified in Recommendation G.721. Figure 1/G.761 indicates the nomenclature used for the three different signal ports A, B and C. + +*Note 1* - Administrations should take into account the guidance given in Recommendation G.721 concerning the use and transmission performance of 32 kbit/s ADPCM . + +*Note 2* - It should be noted that the transcoder equipment described in this Recommendation has a limited capability of transparently transmitting 64 kbit/s data channels and this should be taken into account in the planning of networks which are likely to evolve into an ISDN (see § 3.8). + +This Recommendation is divided into two parts: + +- § 2 contains the interface requirements associated with the port C. These requirements are not only applicable to the 60-channel transcoder equipment, but could be applied, in the future, to other equipment such as a 60-channel multiplex terminal, a 60-channel terminating unit at a TDM switch, or a TDMA terminal. In these latter cases, the A and B interfaces would be virtual. As well as point-to-point operation, account has been taken of multi-destination operation in TDMA applications. +- § 3 contains the requirements which are specific to a 60-channel transcoder equipment realization. + +![Diagram of a 60-channel transcoder showing signal flow between ports A, B, and C. The 'Send side' takes two 2048 kbit/s inputs (A and B) and outputs a single 2048 kbit/s signal at port C. The 'Receive side' takes a 2048 kbit/s input at port C and outputs two 2048 kbit/s signals (A and B). Text below indicates that ports A and B represent 2 x 30 channels at 64 kbit/s (PCM A-law), while port C represents 60 channels at 32 kbit/s (ADPCM).](f89631cc38aa971e8d15cbffe28f1183_img.jpg) + +Diagram description: The diagram shows a transcoder with two main sections: 'Send side' and 'Receive side'. On the left, there are four horizontal lines representing signal flows. The top two are labeled '2048 kbit/s' and point to the 'Send side' through ports 'A' and 'B'. The bottom two are labeled '2048 kbit/s' and point away from the 'Receive side' through ports 'A' and 'B'. On the right, there are two horizontal lines representing signal flows at port 'C'. The top one points away from the 'Send side' and is labeled '2048 kbit/s'. The bottom one points into the 'Receive side' and is labeled '2048 kbit/s'. Below the diagram, there are two text labels: '2 X 30 channels, each channel coded at 64 kbit/s (PCM A-law Rec. G.711)' on the left and '60 channels, each coded at 32 kbit/s (Rec. G.721)' on the right. A small label 'CCITT - 67 150' is also present near the bottom right. + +Diagram of a 60-channel transcoder showing signal flow between ports A, B, and C. The 'Send side' takes two 2048 kbit/s inputs (A and B) and outputs a single 2048 kbit/s signal at port C. The 'Receive side' takes a 2048 kbit/s input at port C and outputs two 2048 kbit/s signals (A and B). Text below indicates that ports A and B represent 2 x 30 channels at 64 kbit/s (PCM A-law), while port C represents 60 channels at 32 kbit/s (ADPCM). + +FIGURE 1/G.761 + +### **60-channel transcoder ports** + +## **2 Characteristics of a 2048 kbit/s signal organized in 64 kbit/s and/or 32 kbit/s time slots (port C)** + +### **2.1 Interface C** + +The electrical characteristics of the 2048 kbit/s interface are in accordance with Recommendation G.703, § 6. + +### **2.2 Frame structure** + +The frame structure is in accordance with Recommendation G.704, § 2.3, with bit 1 of time slot 0 used for the cyclic + +redundancy check (CRC) procedure. + +Time slots 1 to 15 and 17 to 31 each corresponds to: + +- either two 4-bit samples of telephone signals coded using 32 kbit/s ADPCM originating from the same incoming PCM stream (A or B); the bit ordering of the 32 kbit/s signals is such that the 4-bit words are transmitted in bit order starting with bit 1 (see §§ 4.2.2 and 4.2.3 of Recommendation G.721). Bits 1 to 4 correspond to the first 32 kbit/s signal and bits 5 to 8 correspond to the second 32 kbit/s signal; +- or a digital signal at 64 kbit/s. + +Where stream C is transmitting 60 telephone signals, the numbering of the channels and the correspondence between the 64 kbit/s PCM channels in streams A and B and the 32 kbit/s ADPCM channels in stream C are given in Table 1/G.761. + +TABLE 1/G.761 +**Organization of 2048 kbit/s frame for 60-channels at 32 kbit/s (stream C)** + +| | | | | | | | | | | | | | | | | | +|------------------------|---|----|----|----|----|----|----|----|----|-----|-----|-----|-----|-----|-----|-----| +| 8-bit time slot number | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | +| Bits 1-4 of channel | - | 1A | 1B | 3A | 3B | 5A | 5B | 7A | 7B | 9A | 9B | 11A | 11B | 13A | 13B | 15A | +| Bits 5-8 of channel | - | 2A | 2B | 4A | 4B | 6A | 6B | 8A | 8B | 10A | 10B | 12A | 12B | 14A | 14B | 16A | + + + +| | | | | | | | | | | | | | | | | | +|-------------------------|--------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----| +| 8-bits time slot number | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | +| Bits 1-4 of channel | Note 2 | 15B | 17A | 17B | 19A | 19B | 21A | 21B | 23A | 23B | 25A | 25B | 27A | 27B | 29A | 29B | +| Bits 5-8 of channel | Note 2 | 16B | 18A | 18B | 20A | 20B | 22A | 22B | 24A | 24B | 26A | 26B | 28A | 28B | 30A | 30B | + +*Note 1* - The organization of the frame has been chosen to facilitate the direct time slot transfer described in § 3.8. + +*Note 2* - TS16 is foreseen for signalling but speech channels can be transmitted when necessary. These are numbered 31A and 31B respectively for Bits 1-4 and Bits 5-8 (see § 2.5). + +*Note 3* - The numbering of the channels from 1 to 30 and the correspondence with the time slots in PCM stream A (respectively B) are given in Recommendation G.735, § 2. + +### 2.3 Allocation of bits in time slot 0 + +The allocation of the bits in time slot 0 is given in Recommendation G.704, § 2.3, with bit 1 of time slot 0 used for the cyclic redundancy check procedure. + +Bits 3 to 8 in TS0 of those frames not containing the frame alignment signal are used to transmit: + +- alarm indications associated with PCM streams A or B (see §§ 2.6.2 and 2.6.3 dealing with alarm indications); +- spare bits associated with PCM streams A or B (see § 3.3). + +### 2.4 *Frame alignment and CRC procedures* + +The strategy for loss and recovery of frame alignment and CRC multiframe alignment is given in Recommendation G.706, § 4. + +### 2.5 *Allocation of bits in TS16* + +TS16 can be used: + +- either for signalling purposes; namely channel associated signalling (see § 2.5.1) and common channel signalling (see § 2.5.2); +- or, as envisaged in § 5.1 of Recommendation G.704, for the transmission of telephone signals; in this case two samples of telephone signals each coded with 4 bits. Used in this way, stream C can transmit up to 62 telephone signals. Bits 1 to 4 and 5 to 8 of stream C will correspond to 64 kbit/s PCM signals transmitted in TS16 of PCM streams A and B respectively. + +#### 2.5.1 *Channel associated signalling* + +The allocation of bits in TS16 will depend on the number of signalling bits per channel. + +##### 2.5.1.1 *Two or less signalling bits per channel* + +This applies to the digital version of Signalling System R2 (see Recommendation Q.421) specified for international applications. This also applies to a number of national signalling systems. + +TS16 is organized in multiframe. Each multiframe contains 16 consecutive frames, numbered from 0 to 15. The multiframe repetition frequency is 500 Hz. + +###### 2.5.1.1.1 *Allocation of bits in TS16 frame 0* + +Table 2/G.761 indicates the content of TS16 frame 0. + +Bits 1 to 4 are fixed at 0 and constitute the multiframe alignment signal. + +Bits 5 and 8 are used to indicate "AIS in TS16" of PCM streams A and B (see § 2.6.5). + +Bits 6 and 7 are used to transmit the remote alarm indications associated with the multiframe of PCM streams A and B (see § 2.6.6). + +TABLE 2/G.761 +**Content of TS16 frame 0** + +| Bit number | | | | | | | | +|------------|---|---|---|----------------|----------------|----------------|----------------| +| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| 0 | 0 | 0 | 0 | X 5 | X 6 | X 7 | X 8 | + +###### 2.5.1.1.2 *Allocation of bits in TS16 frames 1 to 15* + +Table 3/G.761 indicates the content of TS16 in frames 1 to 15. + +This allocation of bits provides each 32 kbit/s channel with two signalling channels at 500 bit/s nominated "a" and "b" as defined in Recommendation G.704, § 5.1.3.2.2. + +To minimize the risks of simulation of the multiframe alignment signal, special processing of certain signalling bits is carried out as described in § 2.5.1.1.3. + +In the case of direct transfer of some 64 kbit/s time slots of PCM streams A or B, the four bits of TS16 associated with the transferred time slots will be transparently transmitted and allocated in accordance with Table 7/G.704. They will not be subject to the special processing described in § 2.5.1.1.3. The four bits of time slot 16 associated with each of the time slots not used in PCM streams A and B because of the direct transfer will be restituted by the transcoder with the following values: + +a = 0; b = 1; and d = 1, in conformity with Table 9/G.704. + +The signalling distortion of any signalling channel will not be greater than **Error! Bookmark not defined.** 2 ms. + +TABLE 3/G.761 +Content of TS16 frames 1 to 15 + +| Time slot 16 bit number | 1 2 | 3 4 | 5 6 | 7 8 | +|-------------------------|----------------|----------------|----------------|----------------| +| Signalling | Channel
a b | Channel
a b | Channel
a b | Channel
a b | +| Frame 1 | 1A | 2A | 15B | 16B | +| Frame 2 | 1B | 2B | 17A | 18A | +| Frame 3 | 3A | 4A | 17B | 18B | +| Frame 4 | 3B | 4B | 19A | 20A | +| Frame 5 | 5A | 6A | 19B | 20B | +| Frame 6 | 5B | 6B | 21A | 22A | +| Frame 7 | 7A | 8A | 21B | 22B | +| Frame 8 | 7B | 8B | 23A | 24A | +| Frame 9 | 9A | 10A | 23B | 24B | +| Frame 10 | 9B | 10B | 25A | 26A | +| Frame 11 | 11A | 12A | 25B | 26B | +| Frame 12 | 11B | 12B | 27A | 28A | +| Frame 13 | 13A | 14A | 27B | 28B | +| Frame 14 | 13B | 14B | 29A | 30A | +| Frame 15 | 15A | 16A | 29B | 30B | + +*Note* - The organization of the multiframe ensures consistency with the frame and multiframe organization of Recommendation G.704, § 5.1.3 and allows the possibility of the mixed use in stream C of 32 kbit/s and 64 kbit/s channels with their associated signalling. + +###### 2.5.1.1.3 Special processing of signalling bits + +The signalling bits to be transmitted in bit 2 (respectively 4, 6 and 8) of TS16 (frames 1 to 15) are calculated from $B_{n-1}$ , $B_{n-2}$ , $B_{n-3}$ , $b_{n-1}$ and $b_n$ in accordance with Table 4/G.761 where: + +- i) $b_n$ is the signalling bit before processing; +- ii) $B_n$ is the signalling bit after processing, and +- iii) the subscripts $n - 3$ , $n - 2$ , and $n - 1$ relate to previous signalling bits pertaining to the same telephone channel; more specifically, if $b_n$ is a bit with a given number (2, 4, 6 or 8) in any time slot 16 of frames 1 to 15, then $b_{n-1}$ is the bit with the same number, one multiframe earlier. + +*Note 1* - It follows from the above that there are 60 individual and independent processing operations at the same time. + +The reverse processing (after transmission) is in accordance with Table 5/G.761. The reverse processed value $\hat{b}_n$ is deduced from the successive received bits $B_{n-3}$ , $B_{n-2}$ , $B_{n-1}$ , $B_n$ and from the previous value $\hat{b}_{n-1}$ . In the absence of transmission errors in stream C, $\hat{b}_n = b_n$ and there is no increase in signalling distortion. When this is not so, the error multiplication factor lies between 2 and 4. + +When, in the case of fault conditions on multiframe A or B (see Table 9/G.761), the signalling bits need to be forced to state 1, this should be implemented on the unprocessed signalling channels (i.e. before the special processing at the send end or after the reverse processing at the receive end). This does not apply to the cases of "partial AIS stream A (B)" considered in § 2.6.2 where the AIS is all 1s, unprocessed. + +###### 2.5.1.1.4 Loss and recovery of multiframe alignment + +The multiframe alignment should be assumed to have been lost when two consecutive multiframe alignment signals have been received in error. + +The multiframe alignment should be assumed to have been recovered following detection of an all-zero 4-bit word formed by the first four bits of a time slot 16 and an all-zero 4-bit word one multiframe period later. + +##### 2.5.1.2 More than two signalling bits per channel + +See § 3.8. + +#### 2.5.2 Common channel signalling + +TS16 of stream C can be used for common channel signalling. In this case, its content corresponds, without any modification, to that of TS16 of either PCM stream A or PCM stream B. It should be noted that the simultaneous transfer of TS16 from both streams A and B is not envisaged in this case. + +Time slot 16 of PCM stream B (or A) not used because of the direct transfer of time slot 16 of PCM stream A (or B) in time slot 16 of the PCM stream C will be restituted by the transcoder in the form of an all-0s signal or an all-1s signal. + +### 2.6 Alarm indications + +The following alarm indications can be transmitted in stream C. + +#### 2.6.1 AIS stream C + +This means that a fault, common to the 60 channel has been detected in the send side "AIS stream C" is transmitted as an all ones configuration in stream C. + +#### 2.6.2 AIS stream A (respectively B) + +This means that a fault, common to the 30 channels of stream A (respectively B), has been detected in the send side. + +For the send side, the following applies: + +When "AIS stream A" and "AIS stream B" are present simultaneously, then "AIS stream C" should be transmitted. + +When "AIS stream A" (respectively B) is present, but not "AIS stream B" (respectively A), then the information bits and the signalling bits associated with stream B (respectively A) should be transmitted normally and an all ones configuration should be transmitted in the time slots associated with stream A (respectively B) in stream C and the corresponding bits in TS16. In addition, bit 7 (respectively 8) of TS0 not containing the frame alignment signal in stream C should be set to 1 to indicate the "AIS stream A" (respectively B) (see Table 6/G.761). This configuration in stream C is nominated "partial AIS stream A" (respectively "partial AIS stream B"). + +For the receive side, the following applies: + +Partial AIS stream A (respectively B) will be considered as being present if bit 7 (respectively bit 8) is detected at state 1 on three consecutive occasions. + +Partial AIS stream A (respectively B) will be considered as having ceased if bit 7 (respectively 8) is detected at state 0 on three consecutive occasions. + +TABLE 4/G.761 +Processing of signalling bits (send side) + +| Input | State | | | | Output | +|-------|-----------|-----------|-----------|-----------|--------| +| $b_n$ | $b_{n-1}$ | $B_{n-3}$ | $B_{n-2}$ | $B_{n-1}$ | $B_n$ | +| 0 | 0 | 0 | 0 | 0 | 1 | +| 0 | 1 | 0 | 0 | 0 | 0 | +| 0 | 0 or 1 | 0 | 0 | 1 | 0 | +| 0 | 0 or 1 | 0 | 1 | 0 | 1 | +| 0 | 0 or 1 | 0 | 1 | 1 | 0 | +| 0 | 1 | 1 | 0 | 0 | 0 | +| 0 | 0 | 1 | 0 | 1 | 1 | +| 0 | 0 | 1 | 1 | 0 | 1 | +| 0 | 1 | 1 | 1 | 1 | 0 | +| 1 | 1 | 0 | 0 | 0 | 1 | +| 1 | 0 | 0 | 0 | 0 | 0 | +| 1 | 0 or 1 | 0 | 0 | 1 | 1 | +| 1 | 0 or 1 | 0 | 1 | 0 | 0 | +| 1 | 0 or 1 | 0 | 1 | 1 | 1 | +| 1 | 1 | 1 | 0 | 0 | 1 | +| 1 | 0 | 1 | 0 | 1 | 0 | +| 1 | 0 | 1 | 1 | 0 | 0 | +| 1 | 1 | 1 | 1 | 1 | 1 | + +*Note* - Other states may be possible, just after powering-on, which may be avoided by careful design. + +TABLE 5/G.761 + +##### **Processing of signalling bits (receive side)** + +| Input | State | | | | Output | +|-------|-------|-----------|-----------|-----------|--------| +| | $B_n$ | $B_{n-3}$ | $B_{n-2}$ | $B_{n-1}$ | | +| 0 | 0 | 0 | 0 | 0 | 1 | +| 0 | 0 | 0 | 0 | 1 | 0 | +| 1 | 0 | 0 | 0 | 0 | 0 | +| 1 | 0 | 0 | 0 | 1 | 1 | +| 0 | 0 | 0 | 1 | 0 or 1 | 0 | +| 1 | 0 | 0 | 1 | 0 or 1 | 1 | +| 0 | 0 | 1 | 0 | 0 or 1 | 1 | +| 1 | 0 | 1 | 0 | 0 or 1 | 0 | +| 0 | 0 | 1 | 1 | 0 or 1 | 0 | +| 1 | 0 | 1 | 1 | 0 or 1 | 1 | +| 0 | 1 | 0 | 0 | 1 | 0 | +| 1 | 1 | 0 | 0 | 1 | 1 | +| 0 | 1 | 0 | 1 | 0 | 1 | +| 1 | 1 | 0 | 1 | 0 | 0 | +| 0 | 1 | 1 | 0 | 0 | 1 | +| 1 | 1 | 1 | 0 | 0 | 0 | +| 0 | 1 | 1 | 1 | 1 | 0 | +| 1 | 1 | 1 | 1 | 1 | 1 | + +*Note - Other states may be possible, just after powering-on, which may be avoided by careful design.* + +TABLE 6/G.761 + +##### **Use of bits 7 and 8 of TS0 not containing the frame alignment signal in stream C** + +| Bit number | 7 | 8 | Meaning | +|------------|---|---|-------------------------------------------------------------------| +| States | 1 | 0 | AIS Stream A | +| | 0 | 1 | AIS Stream B | +| | 0 | 0 | Normal | +| | 1 | 1 | Indicates that the safeguarding option (see § 3.10) is being used | + +#### **2.6.3 Alarm indication to the remote end for stream A (respectively B)** + +In the send side, bit 3 of TS0, not containing the frame alignment signal of stream A (respectively B) should be transferred to bit 3 (respectively 4) of the corresponding TS0 of stream C. + +In the receive side, bit 3 (respectively 4) of TS0 not containing the frame alignment signal of stream C should be transferred to bit 3 of the corresponding TS0 of stream A (respectively B). + +#### **2.6.4 AIS in TS16 of stream C** + +For channel associated signalling, this means that a fault condition, common to the signalling information associated + +with all 60 channels of stream C has been detected in the send side. "AIS in TS16 of stream C" is transmitted as an all ones configuration in TS16. + +#### 2.6.5 *AIS in TS16 stream A (respectively B)* + +For channel associated signalling, this means that a fault, common to the 30 channels of stream A (respectively B), has been detected in the send side. + +For the send side, the following applies: + +When "AIS in TS16 stream A" and "AIS in TS16 in stream B" are present simultaneously, then "AIS in TS16 of stream C" should be transmitted. When "AIS in TS16 stream A" (respectively B) is present, but not "AIS in TS16 stream B" (respectively A), then the signalling information of stream B (respectively A) should be transmitted normally, and the signalling bits of TS16 of stream C associated with stream A (respectively B) should be transmitted as an all ones configuration. In addition, bit 5 (respectively 8) of TS16 frame 0 should be set to 1 to indicate "AIS in TS16 stream A" (respectively B). + +For the receive side, the following applies: + +AIS in TS16 stream A (respectively B) will be considered as being present if bit 5 (respectively 8) of TS16 frame 0 is detected at state 1 on two consecutive occasions. + +AIS in TS16 stream A (respectively B) will be considered as having ceased if bit 5 (respectively 8) is detected at state 0 on two consecutive occasions. + +#### 2.6.6 *Remote alarm in TS16 of stream A (respectively B)* + +For channel associated signalling, this means that a loss of multiframe alignment in stream A (respectively B) has been detected in the opposite direction of transmission. + +Bit 6 (respectively 7) of TS16 frame 0 of stream C should be put to 1 to transmit this remote alarm indication associated with stream A (respectively B). + +The simultaneous presence of bits 6 and 7 (of TS16 frame 0 of stream C) in state 1 indicates a remote alarm associated with the signalling information of the 60 channels. + +## 3 **Other characteristics of the 60 channel transcoder equipment** + +### 3.1 *Interfaces A and B* + +The electrical characteristics of the two interfaces A and B are in accordance with Recommendation G.703, § 6. + +### 3.2 *Frame structure of streams A and B* + +The frame structure of the 2048 kbit/s streams A and B is given in Recommendation G.704, § 2.3, with bit 1 of time slot 0 used for the CRC procedure. The strategy for loss and recovery of frame alignment and CRC multiframe alignment are given in Recommendation G.706, § 4. + +As indicated in Recommendation G.704, § 5.1, TS16 of streams A and B can be used for the transmission of telephone signals, if not used for signalling purposes, providing two supplementary channels nominated 31A and 31B respectively. (See Table 1/G.761.) + +### 3.3 *Transparent transfer of bits of time slot 0 not containing the frame alignment signal* + +The transcoder equipment should be capable of providing the following two options, the choice between these to be made by the individual Administration or by mutual agreement of the Administrations concerned: + +- bit 4 of time slot 0 not containing the frame alignment signal of streams A and B should be transparently + +transmitted in stream C using bits 5 and 6 respectively of time slot 0 not containing the frame alignment signal of stream C; + +- b) bit 5 should be transmitted in a corresponding way using bits 5 and 6 respectively of stream C. + +### 3.4 *Multiframe structure in TS16 of streams A and B* + +When used for channel associated signalling, TS16 of streams A and B is organized in multiframe as defined in Recommendation G.704, § 5.1.3. The definition of the alarm indications and the criteria for multiframe alignment loss and recovery are given in Recommendation G.735. + +### 3.5 *Absolute delay* + +The overall absolute delay introduced by a pair of interconnected transcoders (i.e. PCM to PCM) should be less than 500 microseconds for any of the 32 kbit/s channels and for any of the transparently transferred 64 kbit/s channels. + +In the case of channel associated signalling, the overall delay introduced by a pair of interconnected transcoders (i.e. PCM to PCM) should be less than 3 milliseconds for any of the signalling channels. + +### 3.6 *Synchronization* + +#### 3.6.1 *Send side* + +So that the equipment may be inserted into a plesiochronous network, or into a synchronous network operating in degraded conditions, both PCM ports A and B at the send side should be provided with frame and multiframe resynchronizing devices, which initiate controlled sample slips (i.e. sample repetitions or deletions) as required. + +It should be possible to synchronize the sending side to any one of the following: + +- timing signal associated with incoming PCM stream A; +- timing signal associated with incoming PCM stream B; +- timing signal associated with incoming stream C; +- external 2048 kHz timing signal (see Recommendation G.703, § 10). + +In the case of synchronization failure, the consequent action is a prompt maintenance alarm (see Table 8/G.761). + +*Note* - Synchronization failure is assumed in case of a fault condition (see Note 2 to Table 8/G.761) on the incoming signal being used for synchronization. + +#### 3.6.2 *Receive side* + +The receiving side should be synchronized to the timing signal associated with incoming stream C. + +*Note* - The organization of the network should be such that controlled sample slips are avoided in normal operating conditions. This can lead to the need to synchronize the sending side to the receiving side in remote 30 channel PCM terminals. In circumstances where slips are unavoidable, they will affect both 32 kbit/s channels and directly transferred 64 kbit/s channels. + +### 3.7 *Jitter* + +The basic jitter requirements at interfaces are covered by the requirements of §§ 2.1 and 3.1. + +When the sending side of the transcoder is synchronized to the incoming PCM stream A or B, and provided both streams A and B are synchronized to each other, slips should not occur when sinusoidal jitter having an amplitude lower than the maximum tolerable input jitter (see Figure 2/G.823) is present at one or both the input ports A and B. + +Jitter transfer characteristics between various signal ports are under study. + +### 3.8 *Direct time slot transfer* + +It should be possible to manually programme the transcoder to transfer transparently at least two time slots from each of the two incoming PCM streams A and B into stream C. + +For national applications, it is sometimes necessary to use more than two signalling bits per channel. In such cases, time slot 16 from PCM streams A and B should be transferred to/from time slots 16 and 17 respectively of stream C. The special processing of signalling bits as described in § 2.5.1.1.3 will not be required. + +To be compatible with Recommendation G.735, § 2, at least TS6 and TS22 of each PCM stream A and B should be transferable. The positions of these time slots in the stream C frame are given below: + +- TS6 of PCM stream A into TS5 of stream C; +- TS6 of PCM stream B into TS6 of stream C; +- TS22 of PCM stream A into TS22 of stream C; +- TS22 of PCM stream B into TS23 of stream C. + +In the case of the transfer of more than two time slots, Table 7/G.761 indicates the allocation up to the maximum possible, taking account of the priority ordering given in Recommendation G.735, § 2. + +If (n) 64 kbit/s time slots of PCM stream A (respectively B) are transferred transparently through the transcoder, then the transmission capabilities of PCM stream A (respectively B) will be limited to (30-2n) channels. More precisely, with the frame structure of stream C given in § 2.2: + +- when TS6 is transferred transparently, channel 5 of the same PCM stream cannot be used; +- when TS22 is transferred transparently, channel 22 of the same PCM stream cannot be used. + +In the case of direct transfer, the transcoder will reconstitute the binary mark sequence corresponding to amplitude 1 for coding law A (see Recommendation G.712, § 4.3), in the non-usable time slot of PCM output streams A and B. + +*Note 1* - The need to transmit transparently more than two time slots per incoming PCM stream is under study. + +*Note 2* - The possibility of remotely controlling the choice of the time slots which are to be transmitted transparently is under study. + +*Note 3* - The octet sequence integrity is maintained by the transcoder in the case of direct transfer of several time slots at 64 kbit/s. + +### 3.9 *In-service monitoring* + +When the PCM to ADPCM and/or the ADPCM to PCM processing functions are multiplexed for 60 channels, in-service monitoring of these processing functions should be provided. This in-service monitoring should be implemented in such a way that it is possible to distinguish between failures affecting the send and receive sides separately. + +Since no PCM (respectively ADPCM) signals are transmitted in TS0, the in-service monitoring can be implemented by inserting test signals into extra channels corresponding to TS0 of PCM streams A and B. + +### 3.10 *Safeguarding of one PCM stream A or B* + +As an option, safeguarding of one PCM tributary can be provided automatically, or otherwise, when a failure of the transcoder digital processing parts, or of the transcoder power supplies, have been detected. In this case the nominated PCM stream, A or B, should, for both directions of transmission, be made to bypass the transcoder and be connected to the transmission link in place of the normal stream C signal. + +The simultaneous presence at state 1 of bits 7 and 8 of TS0 not containing the frame alignment signal in stream C on three consecutive occasions is used to indicate to the remote transcoder that the downstream transcoder has been switched to the safeguarding mode. When the safeguarding option is provided automatically, the procedure for the exchange of information between the two transcoders when switching to and from the safeguarding mode is under study. + +*Note 1* - The choice of the PCM stream ( A or B) which will be safeguarded is made when the equipment is installed. It should be the same at both ends of the transmission link. + +*Note 2* - The use of the safeguarding facility can result in two 2048 kbit/s interfaces in cascade. It is then necessary to ensure, when installing the transcoder, that the combined attenuation of the station cabling at 1024 kHz on both sides of the transcoder is not greater than the maximum attenuation allowed by the equipment connected to the transcoder. + +*Note 3* - Before using the safeguarding facility, it should be checked that the bits 7 and 8 of TS0 not containing the frame alignment signal of the PCM stream to be safeguarded are in the idle state 1 as specified in Recommendation G.704, § 3.3.1.3. + +### 3.11 *Fault conditions and consequent actions* + +#### 3.11.1 *Without safeguarding* + +The fault conditions associated with the frames of streams A, B and C and the consequent actions, when the safeguarding option is not used, are given in Table 8/G.761. + +When channel associated signalling is used, the fault conditions associated with the multiframe of streams A, B and C and their consequent actions are given in Table 9/G.761. + +#### 3.11.2 *With safeguarding* + +When the safeguarding option is provided, Tables 8/G.761 and 9/G.761 must be used, with the exception of the fault condition "transcoder failure" of Table 8/G.761. Instead, the fault conditions and consequent actions given in Table 10/G.761 must be used, with reference to Figure 2/G.761. + +TABLE 7/G.761 + +#### **Order of priority for the transfer of 64 kbit/s time slots from streams A or B to stream C** + +| Time slot in stream A | Time slot in stream B | Time slot in stream C | +|-----------------------|-----------------------|-----------------------| +| 6 | | 5 | +| | 6 | 6 | +| 22 | | 22 | +| | 22 | 23 | +| 14 | | 13 | +| | 14 | 14 | +| 30 | | 30 | +| | 30 | 31 | +| 2 | | 1 | +| | 2 | 2 | +| 18 | | 18 | +| | 18 | 19 | +| 10 | | 9 | +| | 10 | 10 | +| 26 | | 26 | +| | 26 | 27 | +| 4 | | 3 | +| | 4 | 4 | +| 20 | | 20 | +| | 20 | 21 | +| 12 | | 11 | +| | 12 | 12 | +| 28 | | 28 | +| | 28 | 29 | +| 8 | | 7 | +| | 8 | 8 | +| 24 | | 24 | +| | 24 | 25 | +| 17
(Note 1) | | 15 | +| | 17
(Note 1) | 17
(Note 2) | + +*Note 1* - This time slot does not comply with the normal priority ordering given in Recommendation G.735, § 2. + +*Note 2* - Time slot 17 of stream C will not be available for direct transfer of time slot 17 of stream B when the PCM streams employ time slot 16 channel associated signalling with more than two signalling bits per channel (see § 2.5.1.2). + +TABLE 8/G.761 + +#### **Fault conditions on frames A, B and C and consequent actions without safeguarding** + +| Fault conditions | Consequent actions | | | | | | | | | | | | +|----------------------------------|-------------------------------------|-----------------------------------------|---|-------------------------------------|---|-------------------------------------------------------------|------------|-----------------------|-----|-----------------------|-------------------------------------|-------| +| | Prompt maintenance alarm indication | Bit 3 TS0 not containing the FAS stream | | TS0 not containing the FAS stream C | | Stream C - Apply into bits in TS1-31 associated with stream | | AIS applied to stream | | AIS applied to stream | TS0 not containing the FAS stream C | | +| | | A | B | bit 3 | 4 | A (Note 2) | B (Note 3) | A | B | C | bit 7 | bit 8 | +| PCM stream A (Note 1) | Yes (Note 4) | | | | | 11 11 | | | | | 1 | | +| PCM stream B (Note 1) | Yes (Note 4) | | | | | | 11 11 | | | | | 1 | +| PCM streams A and B (Note 1) | Yes (Note 4) | | | | | | | | | Yes | | | +| Stream C (Note 1) | Yes (Note 4) | | | | | | | Yes | Yes | | | | +| TS0 stream A bit 3 to 1 (Note 6) | | | | 1 | | | | | | | | | +| TS0 stream B bit 3 to 1 (Note 6) | | | | | 1 | | | | | | | | +| TS0 stream C bit 3 to 1 (Note 6) | | 1 | | | | | | | | | | | +| TS0 stream C bit 4 to 1 (Note 6) | | | 1 | | | | | | | | | | + +TABLE 8/G.761 (cont.) + +| Consequent actions | Prompt maintenance alarm indication | Bit 3
TS0 not containing the FAS stream | | TS not containing the FAS stream C | | Stream C - Apply into bits in TS1-31 associated with stream | | AIS applied to stream | | AIS applied to stream | TS0 not containing the FAS stream C | | +|---------------------------------------------|-------------------------------------|--------------------------------------------|---|------------------------------------|---|-------------------------------------------------------------|------------|-----------------------|------------------|-----------------------|-------------------------------------|-------| +| | | A | B | 3 | 4 | A (Note 2) | B (Note 3) | A | B | C | bit 7 | bit 8 | +| Fault conditions | | | | | | | | | | | | | +| TS0 stream C bit 7 to 1 | | | | | | | | Yes | | | | | +| TS0 stream C bit 8 to 1 | | | | | | | | | Yes | | | | +| Transcoder failure, send side (Note 5) | Yes | | | | | | | | | Yes | | | +| Transcoder failure, receive side (Note 5) | Yes | | | | | | | Yes | Yes | | | | +| Power supply failure | Yes | | | | | | | Yes, if possible | Yes, if possible | Yes, if possible | | | +| Synchronization failure of the sending side | Yes | | | | | | | | | | | | + +*Note 1* - The fault conditions associated with streams A, B and C are: loss of signal, loss of frame alignment, error ratio greater than $10^{-3}$ as defined in Recommendation G.735, § 4.1. + +*Note 2* - Only in time slots and signalling bits associated with PCM stream A (both for 32 and 64 kbit/s channels). + +*Note 3* - Only in time slots and signalling bits associated with PCM stream B (both for 32 and 64 kbit/s channels). + +*Note 4* - The prompt maintenance alarm indication must be inhibited if the AIS is detected at the corresponding port. + +*Note 5* - The fault condition "transcoder failure" is detected by the in-service monitoring unit. The transcoder is equipped with such a unit if the digital signal processing is time-multiplexed between the 60-channels. + +*Note 6* - These fault conditions are not detected by the transcoder. The indications pass transparently through the transcoder (see § 2.6.3). + +TABLE 9/G.761 + +#### **Fault conditions on multiframes A, B and C and consequent actions** + +| Consequent actions | Prompt maintenance alarm indication | TS 16 frame 0 bit 6 | | TS 16 frame 0 stream C | | TS 16 stream C frames 1-15 | | AIS TS 16 | | AIS TS 16 | TS 16 frame 0 stream C | | +|--------------------------------------------|-------------------------------------|---------------------|---|------------------------|---|----------------------------|------------|-----------|-----|-----------|------------------------|-------| +| | | A | B | 6 | 7 | A (Note 2) | B (Note 3) | A | B | C | bit 5 | bit 8 | +| Fault conditions | | | | | | | | | | | | | +| Multiframe A (Note 1) | Yes (Note 4) | | | | | 1111 | | | | | 1 | | +| Multiframe B (Note 1) | Yes (Note 4) | | | | | | 1111 | | | | | 1 | +| Multiframe A and B (Note 1) | Yes (Note 4) | | | | | | | | | Yes | | | +| Multiframe C (Note 1) | Yes (Note 4) | | | | | | | Yes | Yes | | | | +| Bit 6 TS 16 frame 0 stream A to 1 (Note 5) | | | | 1 | | | | | | | | | +| Bit 6 TS 16 frame 0 stream B to 1 (Note 5) | | | | | 1 | | | | | | | | +| Bit 6 TS 16 frame 0 stream C to 1 (Note 5) | | 1 | | | | | | | | | | | +| Bit 7 TS 16 frame 0 stream C to 1 (Note 5) | | | 1 | | | | | | | | | | +| Bits 5 TS 16 frame 0 stream C to 1 | | | | | | | | Yes | | | | | +| Bits 8 TS 16 frame 0 stream C to 1 | | | | | | | | | Yes | | | | + +Note 1 - The fault condition associated with the three multiframes is the loss of multiframe alignment. + +Note 2 - Only in signalling bits associated with PCM stream A. The 1111.... bits are processed in accordance with § 2.5.1.1.3 and Tables 4/G.761 and 5/G.761 + +Note 3 - Only in signalling bits associated with PCM stream B. The 1111.... bits are processed in accordance with § 2.5.1.1.3 and Tables 4/G.761 and 5/G.761. + +Note 4 - The prompt maintenance alarm indication must be inhibited if the AIS in TS16 is detected at the corresponding port. + +Note 5 - These fault conditions are not detected by the transcoder. The indications pass transparently through the transcoder (see § 2.6.6). + +**TABLE 10/G.761** +**Fault conditions and consequent actions when implementing the safeguarding option** + +| Fault conditions | Consequent actions | | Switching to the safeguarding mode | | AIS in PCM stream not safeguarded | | +|------------------------------------------------------|--------------------|--|------------------------------------|--------|-----------------------------------|--------| +| | | | at (1) | at (2) | at (1) | at (2) | +| Transcoder failure at (1) | | | Yes | | Yes if possible | Yes | +| Power supply failure at (1) | | | | | Yes if possible | Yes | +| TS0 stream C from (1) to (2) bits 7 and 8 in state 1 | | | | Yes | | Yes | + +*Note - The transcoder designations (1) and (2) are indicated in Figure 2/G.761.* + +![Diagram showing two transcoders, (1) and (2), connected in a point-to-point link. Transcoder (1) has inputs A and B on its left and output C on its right. Transcoder (2) has input C on its left and outputs A and B on its right. Arrows indicate the direction of data flow: A and B into (1), C from (1) to (2), and C into (2), with A and B out of (2). A return arrow for C is also shown from (2) to (1). The text 'CCITT - 67170' is at the bottom right.](4356776ca004ecba5d599667a155d7d4_img.jpg) + +Diagram showing two transcoders, (1) and (2), connected in a point-to-point link. Transcoder (1) has inputs A and B on its left and output C on its right. Transcoder (2) has input C on its left and outputs A and B on its right. Arrows indicate the direction of data flow: A and B into (1), C from (1) to (2), and C into (2), with A and B out of (2). A return arrow for C is also shown from (2) to (1). 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requirements** + +![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font overlaid on the globe. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **Transmission systems and media, digital systems and networks** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100-G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200-G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300-G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400-G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450-G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600-G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700-G.799 | +| DIGITAL NETWORKS | G.800-G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900-G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000-G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000-G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000-G.7999 | +| General | G.7000-G.7099 | +| Transport network control aspects | G.7700-G.7799 | +| PACKET OVER TRANSPORT ASPECTS | G.8000-G.8999 | +| ACCESS NETWORKS | G.9000-G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.7710 + +# Common equipment management function requirements + +# Summary + +Recommendation ITU-T G.7710 addresses the equipment management functions (EMFs) inside a transport network element that are common to multiple technologies. For example, common applications are described for date and time, fault management, configuration management, account management, performance management and security management. These applications result in the specification of common EMF functions and their requirements. + +This revision of this Recommendation updates the fault management requirements to support alarm correlation and performance management requirements to support the streaming of performance data. + +## History\* + +| Edition | Recommendation | Approval | Study Group | Unique ID | +|---------|-----------------------------------|------------|-------------|--------------------| +| 1.0 | ITU-T G.7710/Y.1701 | 2001-11-29 | 15 | 11.1002/1000/5635 | +| 2.0 | ITU-T G.7710/Y.1701 | 2007-07-29 | 15 | 11.1002/1000/9171 | +| 2.1 | ITU-T G.7710/Y.1701 (2007) Cor. 1 | 2009-11-13 | 15 | 11.1002/1000/10419 | +| 2.2 | ITU-T G.7710/Y.1701 (2007) Amd. 1 | 2010-07-29 | 15 | 11.1002/1000/10894 | +| 2.3 | ITU-T G.7710/Y.1701 (2007) Cor. 2 | 2011-04-13 | 15 | 11.1002/1000/11134 | +| 3.0 | ITU-T G.7710/Y.1701 | 2012-02-13 | 15 | 11.1002/1000/11508 | +| 3.1 | ITU-T G.7710/Y.1701 (2012) Amd. 1 | 2016-11-13 | 15 | 11.1002/1000/13091 | +| 4.0 | ITU-T G.7710/Y.1701 | 2019-08-29 | 15 | 11.1002/1000/14005 | +| 5.0 | ITU-T G.7710/Y.1701 | 2020-10-29 | 15 | 11.1002/1000/14503 | +| 5.1 | ITU-T G.7710/Y.1701 (2020) Amd. 1 | 2022-11-13 | 15 | 11.1002/1000/15144 | +| 6.0 | ITU-T G.7710 | 2025-11-29 | 15 | 11.1002/1000/16543 | + +## Keywords + +Alarm reporting control, configuration management function, degraded performance, equipment management function, fault management functions, management application function, message communications function, performance management, performance monitoring functions, persistency, severity, thresholding. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +# INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2026 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +| | Page | +|---------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 4 | +| 3.1 Terms defined elsewhere ..... | 4 | +| 3.2 Terms defined in this Recommendation..... | 4 | +| 4 Abbreviations and acronyms ..... | 5 | +| 5 Conventions ..... | 10 | +| 6 Management architecture..... | 10 | +| 6.1 Management network architecture ..... | 12 | +| 6.2 Equipment management architecture ..... | 17 | +| 6.3 Information flows over management points (MP) ..... | 20 | +| 7 Fault management..... | 20 | +| 7.1 RAS quality assurance..... | 21 | +| 7.2 Alarm surveillance..... | 22 | +| 8 Configuration management ..... | 38 | +| 8.1 Hardware ..... | 38 | +| 8.2 Software..... | 39 | +| 8.3 Protection switching ..... | 39 | +| 8.4 Trail termination..... | 40 | +| 8.5 Adaptation ..... | 42 | +| 8.6 Connection..... | 42 | +| 8.7 Threshold of error distribution defects ..... | 45 | +| 8.8 Defect reporting control ..... | 46 | +| 8.9 Alarm severity assignment ..... | 46 | +| 8.10 Alarm reporting control (ARC)..... | 47 | +| 8.11 PM thresholds..... | 47 | +| 8.12 Tandem connection monitoring (TCM) activation..... | 47 | +| 8.13 Date and time..... | 48 | +| 8.14 Fault event filtering ..... | 53 | +| 8.15 Administrative state..... | 54 | +| 9 Account management ..... | 55 | +| 10 Performance management ..... | 55 | +| 10.1 Performance management applications ..... | 55 | +| 10.2 Performance monitoring functions ..... | 69 | +| 11 Security management..... | 95 | +| 12 Control plane management..... | 95 | +| 12.1 Fault reporting management..... | 96 | + +| | | +|----------------------------------------------------------------------------------------------------------------------------|-----| +| Appendix I – Overview of common and technology-specific ITU-T Recommendations..... | 98 | +| Appendix II – Protocol to set the local real-time clock within a few seconds relative to the external time reference ..... | 99 | +| II.1    Measure round trip time ..... | 99 | +| II.2    Calculate the time drift ..... | 99 | +| II.3    Set NE clock..... | 100 | +| Appendix III – SDH and PDH Implementations of termination point mode and port mode .. | 101 | +| Appendix IV Administrative state examples ..... | 102 | +| IV.1    Lock a server layer trail..... | 102 | +| IV.2    Lock a tandem connection..... | 102 | +| Bibliography..... | 104 | + +# Recommendation ITU-T G.7710 + +# Common equipment management function requirements + +# 1 Scope + +This Recommendation specifies those equipment management function (EMF) requirements that are common to multiple (i.e., two or more) transport technologies (e.g., SDH, OTN, Ethernet, MPLS-TP, MTN, Media). Eventually this Recommendation will include all the common management functions. This Recommendation specifies the capabilities required no matter what technology and where there are differences in requirements for a given feature between technologies, the requirements will be specified in the technology-specific Recommendation. See Appendix I for an overview of common and technology-specific Recommendations. A future version of this Recommendation will elaborate on specific requirements within a given capability. + +It must be noted that for a network element (NE) it is not mandatory to support all described applications, and consequently not all specified functions. Depending on the position in the network, the NE may support a subset of the functions. Packages with subsets of these functions can be found in the technology-specific Recommendations. + +The 2019 revision of this Recommendation incorporated the following: + +- Recommendation ITU-T G.7710/Y.1701 Amendment 1 (9/2016); +- Created new clause 12 for control plane function management, including fault event reporting for controller-based restoration. + +The 2020 revision of this Recommendation incorporated the following major updates: + +- Updated clauses 6 and 7 to harmonize with [b-ITU-T G.874], [b-ITU-T G.8051] and [b-ITU-T G.8151]; +- Replaced the term EMS with MCS; +- Updated Figure 3 to use ODUk and packet-based connections for inter-site communications additionally; +- Updated Figure 4 for hybrid NE of management network that supports both a media layer and digital layers; +- Updated Figures 7 and 62 to replace cZZZ-value with MI\_cZZZ; +- Updated Figure 22 and clause 8.8 to replace XXX\_Reported with ZZZ\_Reported to align with [ITU-T G.806]. + +Amendment 1 (Edition 5.1) added specifications for administrative state management in clause 8.15 and Appendix IV. The numbers of the tables and figures were re-sequenced within each clause of the Recommendation. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.800] Recommendation ITU-T G.800 (2016), *Unified functional architecture of transport networks*. + +- [[ITU-T G.805](#)] Recommendation ITU-T G.805 (2000), *Generic functional architecture of transport networks*. +- [[ITU-T G.806](#)] Recommendation ITU-T G.806 (2012), *Characteristics of transport equipment – Description methodology and generic functionality*. +- [[ITU-T G.807](#)] Recommendation ITU-T G.807 (2024), *Generic functional architecture of the optical media layer*. +- [[ITU-T G.808.1](#)] Recommendation ITU-T G.808.1 (2014), *Generic protection switching – Linear trail and subnetwork protection*. +- [[ITU-T G.808.2](#)] Recommendation ITU-T G.808.2 (2019), *Generic protection switching – Ring protection*. +- [[ITU-T G.826](#)] Recommendation ITU-T G.826 (2002), *End-to-end error performance parameters and objectives for international, constant bit-rate digital paths and connections*. +- [[ITU-T G.827](#)] Recommendation ITU-T G.827 (2003), *Availability performance parameters and objectives for end-to-end international constant bit-rate digital paths*. +- [[ITU-T G.828](#)] Recommendation ITU-T G.828 (2000), *Error performance parameters and objectives for international, constant bit-rate synchronous digital paths*. +- [[ITU-T G.829](#)] Recommendation ITU-T G.829 (2002), *Error performance events for SDH multiplex and regenerator sections*. +- [[ITU-T G.7702](#)] Recommendation ITU-T G.7702 (2022), *Architecture for SDN control of transport networks*. +- [[ITU-T G.7712](#)] Recommendation ITU-T G.7712/Y.1703 (2019), *Architecture and specification of data communication network*. +- [[ITU-T G.8601](#)] Recommendation ITU-T G.8601/Y.1391 (2006), *Architecture of service management in multi-bearer, multi-carrier environment*. +- [[ITU-T M.20](#)] Recommendation ITU-T M.20 (1992), *Maintenance philosophy for telecommunication networks*. +- [[ITU-T M.2101](#)] Recommendation ITU-T M.2101 (2003), *Performance limits for bringing-into-service and maintenance of international multi-operator SDH paths and multiplex sections*. +- [[ITU-T M.2110](#)] Recommendation ITU-T M.2110 (2002), *Bringing into service international multi-operator paths, sections and transmission systems*. +- [[ITU-T M.2120](#)] Recommendation ITU-T M.2120 (2002), *International multi-operator paths, sections and transmission systems fault detection and localization procedures*. +- [[ITU-T M.2140](#)] Recommendation ITU-T M.2140 (2000), *Transport network event correlation*. +- [[ITU-T M.3010](#)] Recommendation ITU-T M.3010 (2000), *Principles for a telecommunications management network*. +- [[ITU-T M.3013](#)] Recommendation ITU-T M.3013 (2000), *Considerations for a telecommunications management network*. + +- [ITU-T M.3016.x] Recommendation ITU-T M.3016.x-series (2005), *Security for the management plane*. +- [[ITU-T M.3016.0](#)] Recommendation ITU-T M.3016.0 (2005), *Security for the management plane: Overview*. +- [[ITU-T M.3016.1](#)] Recommendation ITU-T M.3016.1 (2005), *Security for the management plane: Security requirements*. +- [[ITU-T M.3016.2](#)] Recommendation ITU-T M.3016.2 (2005), *Security for the management plane: Security services*. +- [[ITU-T M.3016.3](#)] Recommendation ITU-T M.3016.3 (2005), *Security for the management plane: Security mechanism*. +- [[ITU-T M.3016.4](#)] Recommendation ITU-T M.3016.4 (2005), *Security for the management plane: Profile proforma*. +- [[ITU-T M.3060](#)] Recommendation ITU-T M.3060/Y.2401 (2006), *Principles for the Management of Next Generation Networks*. +- [[ITU-T M.3100](#)] Recommendation ITU-T M.3100 (2005), *Generic network information model*. +- [[ITU-T M.3400](#)] Recommendation ITU-T M.3400 (2000), *TMN management functions*. +- [[ITU-T Q.821](#)] Recommendation ITU-T Q.821 (2000), *Stage 2 and Stage 3 description for the Q3 interface – Alarm Surveillance*. +- [[ITU-T Q.822](#)] Recommendation ITU-T Q.822 (1994), *Stage 1, stage 2 and stage 3 description for the Q3 interface – Performance management*. +- [[ITU-T X.700](#)] Recommendation ITU-T X.700 (1992), *Management framework for Open Systems Interconnection (OSI) for CCITT applications*. +- [[ITU-T X.701](#)] Recommendation ITU-T X.701 (1997), *Information technology – Open Systems Interconnection – Systems management overview*. +- [[ITU-T X.720](#)] Recommendation ITU-T X.720 (1992), *Information technology – Open Systems Interconnection – Structure of management information: Management information model*. +- [[ITU-T X.731](#)] Recommendation ITU-T X.731 (1992), *Information technology – Open Systems Interconnection – Systems management: State management function*. +- [[ITU-T X.733](#)] Recommendation ITU-T X.733 (1992), *Information technology – Open Systems Interconnection – Systems Management: Alarm reporting function*. +- [[ITU-T X.734](#)] Recommendation ITU-T X.734 (1992), *Information technology – Open Systems Interconnection – Systems Management: Event report management function*. +- [[ITU-T X.735](#)] Recommendation ITU-T X.735 (1992), *Information technology – Open Systems Interconnection – Systems Management: Log control function*. +- [[ITU-T X.744](#)] Recommendation ITU-T X.744 (1996), *Information technology – Open Systems Interconnection – Systems Management: Software management function*. +- [[ITU-T X.754](#)] Recommendation ITU-T X.754 (2000), *Enhanced Event Control Function*. + +| | | +|-------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T X.811] | Recommendation ITU-T X.811 (1995), Information technology – Open Systems Interconnection – Security frameworks for open systems: Authentication framework. | +| [ITU-T X.815] | Recommendation ITU-T X.815 (1995), Information technology – Open Systems Interconnection – Security frameworks for open systems: Integrity framework. | +| [ISO/IEC 27002] | ISO/IEC 27002:2022, Information security, cybersecurity and privacy protection – Information security controls. | + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +### 3.1.1 Terms defined in [ITU-T G.806]: + +- atomic function (AF); +- management point (MP). + +### 3.1.2 Terms defined in [ITU-T M.3010]: + +- network element (NE); +- network element function (NEF); +- workstation function (WF); +- Q-Interface; +- operations system (OS). + +### 3.1.3 Term defined in [ITU-T M.3013]: + +- message communication function (MCF). + +### 3.1.4 Term defined in [ITU-T M.3100]: + +- management interface. + +### 3.1.5 Term defined in [ITU-T X.700]: + +- managed object. + +### 3.1.6 Terms defined in [ITU-T X.701]: + +- agent; +- manager. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 embedded communication channel (ECC):** An ECC provides a logical operations channel between NEs, utilizing, e.g., a data communication channel (DCC) within an SDH or a general communication channel (GCC 0-2) within an OTN as its physical layer. + +**3.2.2 local craft terminal (LCT):** A terminal used for maintenance purposes at the network element (NE). + +**3.2.3 management application function (MAF):** An application process that participates in system management. Each NE and operations system (OS) must support a MAF. A MAF is the origin and termination for all TMN messages. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------------------|----------------------------------------------------------------------------------------------| +| AF | Atomic Function | +| AI | Artificial Intelligence | +| AIS | Alarm Indication Signal | +| ALC | Alarm Correlation | +| ALM | Alarm reporting | +| AP | Access Point | +| API | Access Point Identifier | +| AR | Availability Ratio | +| ARC | Alarm Reporting Control | +| AST | Alarm Status function | +| ASY | Alarm Synchronization function | +| AvFb | Bidirectional Availability Filter function | +| AvFu | Unidirectional Availability Filter function | +| BB | Background Block | +| BBC | Background Block Count | +| BBE | Background Block Error | +| BBER | Background Block Error Ratio | +| BD | Block Delay | +| BDI | Backward Defect Indication | +| BDV | Block Delay Variation | +| BEI | Backward Error Indication | +| BER | Bit Error Rate | +| BIS | Bringing-Into-Service | +| BUT | Begin Unavailable Time | +| CI | Characteristic Information | +| CMISE | Common Management Information Service Element | +| CMSN | Client Management Subnetwork | +| CP | Connection Point | +| CPL | Current Problem List function | +| CPU | Central Processing Unit | +| CSES | Consecutive Severely Errored Second | +| CTP | Connection Termination Point | +| Cur15m- x | Current 15-minute register function ( x = c, s, t for Counter, Snapshot and Tidemark) | +| Cur24h- x | Current 24-hour register function ( x = c, s, t for counter, snapshot and tidemark) | +| DCN | Data Communication Network | + +| | | +|--------|----------------------------------------------------------------------------------------------------------------| +| DEG | Degraded | +| DEGM | Degraded Monitor period | +| DEGTHR | Degraded Threshold | +| DFE | Decision Feedback Equalizer | +| DS | Defect Second | +| EB | Errored Block | +| EBC | Errored Block Count | +| EBR | Errored Block Ratio | +| ECC | Embedded Communication Channel | +| EDC | Error Detection Code | +| EMF | Equipment Management Function | +| EMS | Element Management System | +| EN | European Norm | +| ES | Errored Second | +| ESR | Errored Second Ratio | +| ETH | Ethernet MAC Layer | +| EUT | End Unavailable Time | +| EXE | Excessive | +| FAS | Frame Alignment Signal | +| FBBE | Far-end Background Block Error | +| FCAPS | Fault management, Configuration management, Account management, Performance management and Security management | +| FD | Frame Delay | +| FDI | Forward Defect Indication | +| FDV | Frame Delay Variation | +| FEC | Forward Error Correction | +| FE-Mon | Far-End performance Monitor | +| FES | Far-end Errored Second | +| FLR | Frame Loss Ratio | +| FM | Fault Management | +| FOP | Failure of Protocol | +| FP | Flow Point | +| FPME | Far-end Performance Monitoring Event | +| FSES | Far-end Severely Errored Second | +| GMPLS | Generalized Multi-Protocol Label Switching | +| GMT | Greenwich Mean Time | +| GNE | Gateway Network Element | + +| | | +|-------|-----------------------------------------| +| GPS | Global Positioning System | +| IAE | Incoming Alignment Error | +| Id | Identifier | +| IP | Internet Protocol | +| KPI | Key Performance Indicator | +| LAN | Local Area Network | +| LB | Lost Block | +| LBC | Lost Block Count | +| LBR | Lost Block Ratio | +| LCN | Local Communication Network | +| LCT | Local Craft Terminal | +| LF | Lost Frames | +| LOC | Loss Of Continuity | +| LOF | Loss Of Frame | +| LOG | Event notification Logging function | +| LOM | Loss Of Multiframe | +| LOP | Loss Of Pointer | +| LOS | Loss Of Signal | +| LTC | Loss of Tandem Connection | +| MAF | Management Application Function | +| MC | Management and Control | +| MCC | Management Communication Channel | +| MCF | Message Communication Function | +| MCS | Management and Control System | +| MD | Mediation Device | +| MEGID | Maintenance Entity Group Identifier | +| MEPID | MEG End Point Identifier | +| MF | Mediation Function | +| MI | Management Information | +| MIB | Management Information Base | +| MIPI | MEG Intermediate Point Identifier | +| ML | Machine Learning | +| MO | Managed Object | +| MON | Monitored | +| MP | Management Point | +| MSIM | Multiplex Structure Identifier Mismatch | +| MSP | Multiplex Section Protection | + +| | | +|---------------|-------------------------------------------------------------------------| +| NALM | No Alarm reporting | +| NBBE | Near-end Background Block Error | +| NE | Network Element | +| NEA | Network Element Alarm | +| NEF | Network Element Function | +| NEL | Network Element Level | +| NE-Mon | Near-End performance Monitor | +| NES | Near-end Errored Second | +| NGN | Next Generation Network | +| NMON | Not Monitored | +| NPME | Near-end Performance Monitoring Event | +| NSES | Near-end Severely Errored Second | +| O.MSN | Optical Management Subnetwork | +| OCh | Optical Channel | +| OCI | Open Connection Indication | +| ODI | Outgoing Defect Indication | +| ODU | Optical Data Unit | +| OI | Outage Intensity | +| OMSP | Optical Multiplex Section Protection | +| OPS | Operational State function | +| ORF- x | Out of Range Function ( x = o, for overflow and u for underflow) | +| ORR | Out of Range Report | +| OS | Operations System | +| OSF | Operations System Function | +| OSNR | Optical Signal to Noise Ratio | +| OTN | Optical Transport Network | +| PDH | Plesiochronous Digital Hierarchy | +| PJE | Pointer Justification Event | +| PLM | Payload Mismatch | +| PM | Performance Management | +| PMC | Performance Monitoring Clock | +| PMF | Performance Monitoring Function | +| PRBS | Pseudo-Random Binary Sequence | +| PRS | Persistency filter | +| PSC | Protection Switch Count | +| PSE | Protection Switch Event | +| PSL | Path Signal Label | + +| | | +|------------------|---------------------------------------------------------------------------------------------| +| QoS | Quality of Service | +| RAS | Reliability, Availability and Survivability | +| RDI | Remote Defect Indication | +| Rec15m- x | Recent 15-minute register function ( x = c, s, t for Counter, Snapshot and Tidemark) | +| Rec24h- x | Recent 24-hour register function ( x = c, s, t for Counter, Snapshot and Tidemark) | +| REI | Remote Error Indication | +| REP | Reportable failure function | +| RTC | Real-Time Clock | +| RTR | Reset Threshold Report | +| S.MSN | SDH Management Subnetwork | +| SCC | Signalling Communication Channel | +| SDH | Synchronous Digital Hierarchy | +| SEM | Single-Ended Maintenance | +| SEP | Severely Errored Period | +| SEPI | Severely Errored Period Intensity | +| SES | Severely Errored Second | +| SESR | Severely Errored Second Ratio | +| SEV | Severity assignment function | +| SLA | Service Level Agreement | +| SMSN | Server Management Subnetwork | +| SPDF | Streamed Performance Data Filtering function | +| SSF | Server Signal Fail | +| STA | Station Alarms function | +| TAN | TMN Alarm event Notification function | +| TBC | Transmitted Block Count | +| TBmin | Transmitted Blocks minimum | +| TCM | Tandem Connection Monitoring | +| TCP | Termination Connection Point | +| TEP | TMN Event Pre-processing function | +| TF | Transmitted Frames | +| TFP | Termination Flow Point | +| ThrF-st | standing condition Threshold Function | +| ThrF-tr | transient condition Threshold Function | +| TI_CK | Timer Clock signal | +| TIM | Trace Identifier Mismatch | +| TMN | Telecommunication Management Network | +| TP | Termination Point | + +| | | +|-------|-------------------------------------------| +| TR | Threshold Report | +| TTI | Trail Trace Identifier | +| UAS | Unavailable Second | +| UAT | Unavailable Time | +| UNA | Unit Alarms function | +| UNEQ | Unequipped | +| UTC | Coordinated Universal Time | +| VC | Virtual Container | +| WAN | Wide Area Network | +| WS | Workstation | +| x.MN | technology-specific Management Network | +| x.MSN | technology-specific Management Subnetwork | +| x.NE | technology-specific Network Element | + +# 5 Conventions + +Naming convention for management (sub)networks and network elements: + +The general abbreviation for management subnetworks is x.MSN and for management networks it is x.MN. The general abbreviation for network elements is x.NE. The prefix "x." is a placeholder for the various technologies that are managed e.g., "x" could be replaced by: + +- "O" meaning an optical management (sub)network or network element. +- "S" meaning SDH management (sub)network or network element. + +# 6 Management architecture + +The management of the transport network is based upon a multi-tiered distributed management system as described in [ITU-T M.3010] and based on an NGN management architecture as described in [ITU-T M.3060]. Each tier provides a predefined level of network management capabilities. The lowest tier of this organizational model, illustrated in Figure 6-1, includes the network element functions (NEFs) that provide the transport service and the operations system functions (OSFs) at the element management level. The management application function (MAF) within the NEFs and OSFs provides the management support. The MAF at each entity can include agents only, managers only, or both agents and managers. Entities that include managers are capable of managing other entities. + +The management communication to peer NEFs and/or operations system functions (OSFs) is provided via the message communication function (MCF) within each entity (NEF, OSF). The user can access the management of the transport network via a local craft terminal (LCT) attached to the NEF or via a workstation (WS) attached to the OSF. + +The specification of the MAF and the MCF in the NEF is within the scope of this Recommendation. + +![Figure 6-1: Management organizational model diagram. The diagram shows three Network Elements (NEFs) connected horizontally by an Embedded Communication Channel (ECC) labeled 'Q (ECC)'. Each NEF contains a stack of layers: AF (bottom), D&T and FCAPS (middle), MAF and MIB (top of NEF), and MCF (top). Vertical arrows connect MCF to MAF, MAF to MIB, D&T to FCAPS, and D&T to AF. Above the NEFs, two Local Craft Terminals (LCTs) and a Work Station (WS) are shown. The LCTs are connected to the MCF of the middle and right NEFs via a 'Q (LAN, WAN)' interface. The WS is connected to the MCF of the right NEF via a 'Q (LAN, WAN)' interface. Each LCT and WS also has an internal stack with MCF, MAF, and MIB layers, connected by an 'OSF' (Open System Foundation) interface. The rightmost NEF has a small text label 'G.7710-Y.1701(20)-Amd.1(22)_F6-1' below it.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +Figure 6-1: Management organizational model diagram. The diagram shows three Network Elements (NEFs) connected horizontally by an Embedded Communication Channel (ECC) labeled 'Q (ECC)'. Each NEF contains a stack of layers: AF (bottom), D&T and FCAPS (middle), MAF and MIB (top of NEF), and MCF (top). Vertical arrows connect MCF to MAF, MAF to MIB, D&T to FCAPS, and D&T to AF. Above the NEFs, two Local Craft Terminals (LCTs) and a Work Station (WS) are shown. The LCTs are connected to the MCF of the middle and right NEFs via a 'Q (LAN, WAN)' interface. The WS is connected to the MCF of the right NEF via a 'Q (LAN, WAN)' interface. Each LCT and WS also has an internal stack with MCF, MAF, and MIB layers, connected by an 'OSF' (Open System Foundation) interface. The rightmost NEF has a small text label 'G.7710-Y.1701(20)-Amd.1(22)\_F6-1' below it. + +**Figure 6-1 – Management organizational model** + +The embedded communication channel (ECC) provides a logical operations channel between network elements (NEs) for transferring management and/or signalling information. Note that some technologies provide separate communication channels for management (MCC) and signalling (SCC). Whenever the generic term ECC is used in this Recommendation, it mainly focuses on the utilization of the ECC for management (i.e., MCC only). + +The local craft terminal (LCT) and its interface to the NEF, shown in Figure 6-1, are not within the scope of this Recommendation. + +## 6.1 Management network architecture + +### 6.1.1 Relationship between TMN, x.MN and x.MSN + +The telecommunication management network (TMN) may consist of several technology-specific management networks (x.MN), which in turn may be partitioned into management subnetworks (x.MSN). An example of these relationships is shown in Figure 6-2 for an optical management network, an SDH management network, and another (x) management network. + +![Diagram illustrating the hierarchy of management networks: TMN contains x.MN, which contain x.MSN.](4356776ca004ecba5d599667a155d7d4_img.jpg) + +The diagram illustrates the hierarchical relationship between management networks. At the top level, a large rectangle represents the 'Telecommunication management network'. Inside this rectangle, there are two boxes at the top: 'Optical management network' on the left and 'SDH management network' on the right. Below these, centered, is a third box labeled 'x Management network'. Each of these three boxes contains a dashed rectangle representing a set of management subnetworks. The 'Optical management network' box contains 'O.MSN-1', 'O.MSN-2', an ellipsis, and 'O.MSN-n'. The 'SDH management network' box contains 'S.MSN-1', 'S.MSN-2', an ellipsis, and 'S.MSN-k'. The 'x Management network' box contains 'x.MSN-1', 'x.MSN-2', an ellipsis, and 'x.MSN-r'. + +Diagram illustrating the hierarchy of management networks: TMN contains x.MN, which contain x.MSN. + +G.7710-Y.1701(20)-Amd.1(22)\_F6-2 + +Figure 6-2 – TMN, x.MN and x.MSN partitioning + +Figure 6-3 shows an example of a management network and its integration into the telecommunication management network (TMN). The data communication network (DCN) between these physical blocks is defined in [ITU-T G.7712]. + +![Diagram of a management network example showing the integration of a management network into a TMN. The TMN is represented by a yellow cloud containing OS1, MD_A, MD_E, and OS2. External entities (represented by person icons) connect to OS1 and MD_A via F-interfaces, and to OS2 via an F-interface. Q-interfaces connect OS1 to MD_A, MD_A to MD_E, MD_E to OS2, and OS2 to GNE_j. Below the TMN cloud are three technology-specific management subnetworks: x.MSN-1, x.MSN-2, and x.MSN-n. x.MSN-1 contains y.NE_A, GNE_A, NE_B, y.NE_B, NE_C, NE_D, and NE_E. x.MSN-2 contains GNE_E, GNE_G, NE_F, NE_H1, NE_H2, NE_I, and NE_L. x.MSN-n contains GNE_j, NE_K1, NE_K2, NE_M, and NE_L. GNE_A, GNE_E, and GNE_j are connected to the TMN cloud via Q-interfaces. GNE_A connects to NE_B via an LCN Non-ECC link and to NE_C via an ECC link. NE_B connects to y.NE_B via an LCN link and to NE_C via an ECC link. NE_C connects to NE_D via an ECC link. GNE_E connects to NE_F via an ECC link. GNE_G connects to NE_H1 and NE_H2 via ECC links. NE_H1 and NE_H2 are connected by an LCN Non-ECC link. NE_H1 connects to NE_I via an ECC link. NE_I connects to NE_L via an ECC link. GNE_j connects to NE_K1 and NE_K2 via ECC links. NE_K1 and NE_K2 are connected by an LCN Non-ECC link. NE_K2 connects to NE_M via an ECC link. NE_K2 also connects to NE_L via an ECC link. A legend at the bottom defines the symbols: circles for communication blocks, a yellow cloud for x.MSN external DCN, solid double-headed arrows for Q-interfaces, solid single-headed arrows for F-interfaces, dashed double-headed arrows for ECC, and dashed single-headed arrows for Non-ECC links. A list on the right defines the abbreviations: ECC (Embedded communication channel), GNE (Gateway network element), LCN (Local communication network), MD (Mediation device), NE (Network element), OS (Operations system), x.MSN (technology-specific management subnetwork), and y.NE (other technology network element).](7f25db95ce3916c0e09803b861a2f7bc_img.jpg) + +Telecommunications management network (TMN) + +Legend: + +- Communication blocks +- x.MSN external data communication network +- Communication links using standard Q-interface protocol +- Communication links using standard F-interface protocol +- ECC +- Non-ECC link, such as ODUk, packet-based connection + +Abbreviations: + +- ECC Embedded communication channel +- GNE Gateway network element +- LCN Local communication network +- MD Mediation device +- NE Network element +- OS Operations system +- x.MSN technology-specific management subnetwork +- y.NE other technology network element + +Diagram of a management network example showing the integration of a management network into a TMN. The TMN is represented by a yellow cloud containing OS1, MD\_A, MD\_E, and OS2. External entities (represented by person icons) connect to OS1 and MD\_A via F-interfaces, and to OS2 via an F-interface. Q-interfaces connect OS1 to MD\_A, MD\_A to MD\_E, MD\_E to OS2, and OS2 to GNE\_j. Below the TMN cloud are three technology-specific management subnetworks: x.MSN-1, x.MSN-2, and x.MSN-n. x.MSN-1 contains y.NE\_A, GNE\_A, NE\_B, y.NE\_B, NE\_C, NE\_D, and NE\_E. x.MSN-2 contains GNE\_E, GNE\_G, NE\_F, NE\_H1, NE\_H2, NE\_I, and NE\_L. x.MSN-n contains GNE\_j, NE\_K1, NE\_K2, NE\_M, and NE\_L. GNE\_A, GNE\_E, and GNE\_j are connected to the TMN cloud via Q-interfaces. GNE\_A connects to NE\_B via an LCN Non-ECC link and to NE\_C via an ECC link. NE\_B connects to y.NE\_B via an LCN link and to NE\_C via an ECC link. NE\_C connects to NE\_D via an ECC link. GNE\_E connects to NE\_F via an ECC link. GNE\_G connects to NE\_H1 and NE\_H2 via ECC links. NE\_H1 and NE\_H2 are connected by an LCN Non-ECC link. NE\_H1 connects to NE\_I via an ECC link. NE\_I connects to NE\_L via an ECC link. GNE\_j connects to NE\_K1 and NE\_K2 via ECC links. NE\_K1 and NE\_K2 are connected by an LCN Non-ECC link. NE\_K2 connects to NE\_M via an ECC link. NE\_K2 also connects to NE\_L via an ECC link. A legend at the bottom defines the symbols: circles for communication blocks, a yellow cloud for x.MSN external DCN, solid double-headed arrows for Q-interfaces, solid single-headed arrows for F-interfaces, dashed double-headed arrows for ECC, and dashed single-headed arrows for Non-ECC links. A list on the right defines the abbreviations: ECC (Embedded communication channel), GNE (Gateway network element), LCN (Local communication network), MD (Mediation device), NE (Network element), OS (Operations system), x.MSN (technology-specific management subnetwork), and y.NE (other technology network element). + +G.7710-Y.1701(20)-Amd.1(22)\_F6-3 + +**Figure 6-3 – Management network example** + +NEs must support management communications functions. The MCF of an NE initiates or terminates (in the sense of the lower protocol layers), forwards, or otherwise processes management messages over ECCs, or over other DCN interfaces. + +### 6.1.2 Access to the x.MSN + +Access to the x.MSN is always by means of an NE functional block. The NE may be connected to other parts of the TMN through the following sets of interfaces: + +- Local craft terminal; +- Mediation device (Q-interface); +- Operations system interfaces (Q-interface). + +The functionality required to be supported by the NE will determine the type of Q-interface to be provided. For instance, the two main varieties of NEs expected are the NEs with mediation functions (MF) and "regular" NEs. + +### 6.1.3 x.MSN requirements + +In Figure 6-3, a number of requirements should be noted concerning the architecture of the x.MSN: + +#### a) *Multiple NEs at a single site* + +Multiple, addressable NEs may be present at a single physical location. For example, in Figure 6-3, NEE and NEG may be collocated at a single equipment site. + +#### b) *NEs and their communications functions* + +The message communication function of an NE initiates/terminates (in the sense of the lower protocol layers), routes, or otherwise processes management messages over ECCs, or other data communication network interfaces connected via an external Q-interface. + +#### c) *Inter-site communications* + +The inter-site or inter-office communications link between the NEs will normally be provided by the ECCs. Ethernet WAN can also be used to carry communications that require a higher throughput or a lower latency than those that could be provided by the ECCs. + +#### d) *Intra-site communications* + +Within a particular site, the NEs may communicate via an intra-site ECC or via an Ethernet LAN. Figure 6-3 illustrates both instances of this interface. + +All the NEs are required to either terminate an Ethernet LAN (for intra site communication with a co located NE) or an ECC. In addition, the NE may also be required to support other DCN interfaces. + +### 6.1.4 x.MSN data communication network + +It is intended that this Recommendation should place no restriction on the physical transport topology to support management communications. Thus, it is expected that the supporting data communication network (DCN) may contain string (bus), star, ring or mesh topologies. The DCN also supports seamless connectivity with remote transport domains and NEs as specified in [ITU-T G.8601] as well as with termination points located in NEs under control by a third-party network operator as specified in [ITU-T G.8601]. + +See [ITU-T G.7712] for the management of DCN's architectures and specifications, including the network layer protocol. + +Each management subnetwork (x.MSN) must have at least one NE which is connected to an OS (possibly via a mediation device). This NE is called a gateway network element (GNE) and is illustrated in Figure 6-3. The GNE should be able to perform an intermediate system network layer routing function for DCN messages destined for any end system in the x.MSN. Messages passing between the OS and any of the end systems in the subnetwork are routed through the GNE and, in general, other intermediate systems. + +NOTE – This is a specific instance of the general requirement that messages passing between communicating subnetworks shall use the network layer relay. + +The other NEs within the management subnetwork (x.MSN) must, at least, be able to perform an end system network layer function to terminate the DCN messages destined to itself. They may also be able to perform an intermediate system network layer routing function for DCN messages destined to any other end system in the x.MSN or to the OS. + +### 6.1.5 Management of the DCN + +NEs communicate via the DCN. In order to have the DCN operate properly, a number of management functions are required, including: + +- 1) retrieval of network parameters to ensure compatible functioning, e.g., packet size, timeouts, quality of service, window size, etc.; +- 2) establishment of message routing between DCN nodes; +- 3) management of DCN network addresses; +- 4) retrieval of operational status of the DCN service at a given node; +- 5) capability to enable/disable access to the DCN (if supporting a management protocol); +- 6) get the topology view of the DCN. + +### 6.1.6 Remote log-in + +For remote log-in security, see requirements in [ITU-T M.3016.x]. + +### 6.1.7 Relationship between technology domains + +The transport network has to deal with many technology domains (i.e., connection-oriented and connectionless). When they are connected together, these domains create a client-server relationship between them. This situation leads to *hybrid* NEs that handle a specific technology internally and in the transport ports, but also have access ports, which are able to convert from another technology to this specific one. + +Figure 6-4 shows such a client-server relationship between two different management subnetworks. Figure 6-4(a) exemplifies the case that the two subnetworks are different digital network technologies. NEs C and D contain technology B (server) layer network entities and technology A (client) layer network entities. These NEs are therefore part of more than one type of management subnetwork. The technology A ports in NEs C and D can be managed in one of the following ways: + +- as an entity that is managed by the CMSN OSF; +- as an entity that is managed by the SMSN OSF; +- as a stand-alone fragment which is not managed except as an equipment fragment. + +This may be achieved by one or more agents within such an NE, using one or more protocols to communicate with their respective OSFs. In this example, there is a separate OSF (one for the CMSN and one for the OMSN) for each domain, which may or may not be collocated in the same physical OS. + +Figure 6-4(b) exemplifies the case that two subnetworks are digital and media network technologies. The technology digital ports in NEs C and D can be managed in one of the three ways above. + +![Diagram (a) showing network architecture with Client management subnetwork technology A (CMSN A) and Server management subnetwork technology B (SMSN B).](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +The diagram illustrates a network architecture with the following components and layers: + +- Client management subnetwork technology A (CMSN A):** A large dashed box at the top containing three vertical stacks of network elements (NEs). + - The left stack is labeled **NE A (techn. A)** at the bottom. + - The right stack is labeled **NE B (techn. A)** at the bottom. + - On the far right, three layers are identified: **Layer network X (techn. A)**, **Layer network Y (techn. A)**, and **Layer network Z (techn. A)**. +- Server management subnetwork technology B (SMSN B):** A large dashed box in the center containing two vertical stacks of NEs and a central horizontal stack. + - The left stack is labeled **NE C (hybrid techn. A/B)** at the bottom. It includes layers **Layer network S (techn. B)** and **Layer network T (techn. B)**. + - The right stack is labeled **NE D (hybrid techn. A/B)** at the bottom. It also includes layers **Layer network S (techn. B)** and **Layer network T (techn. B)**. + - The central horizontal stack is labeled **NE E (techn. B)** at the bottom. + - Between the left and right stacks, two layers are identified: **Layer network R (techn. B)**. +- Technology A port:** Two dashed boxes, one on the left and one on the right, labeled "Technology A port". These boxes represent interfaces between the CMSN A and SMSN B stacks. +- Legend:** + - Network element (NE) + - Technology B layers + - Technology A layers + +G.7710-Y.1701(20)-Amd.1(22)\_F6-4a + +Diagram (a) showing network architecture with Client management subnetwork technology A (CMSN A) and Server management subnetwork technology B (SMSN B). + +(a) + +![Diagram (b) showing management network relationships between digital and optical media subnetworks. It illustrates the flow of signals and management information between NE A, NE B, NE C, and NE D through various layers (X, Y, Z) and components like OTSi, OA, OSC, and F. A central amplifier site is also shown.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +The diagram illustrates the management network relationships for digital to media subnetworks. It shows four Network Elements (NEs): NE A (digital techn.), NE B (digital techn.), NE C (hybrid techn. Digital/media), and NE D (hybrid techn. Digital/media). These NEs are connected through a central 'Server management subnetwork optical media (SMSN media)' which includes an 'Amplifier site (Optical media)'. Above this is the 'Client management subnetwork digital technology (CMSN digital)'. The diagram is divided into three layer networks: Layer network X, Layer network Y, and Layer network Z. Each NE has a 'Digital port' that connects to the CMSN digital. The signal path from NE A and NE B passes through the digital ports, then through OTSi (Optical Transport Section Interface), OA (Optical Amplifier), OSC (Optical Supervisory Channel), and F (Filter) components. The signal from NE C and NE D also passes through similar components. The amplifier site contains two OSCs, an OA, and two F components. The legend defines the symbols: solid line for Network element (NE), dashed line for Optical media layers, dash-dot line for Digital layers, circle with a dot for Optical coupler-splitter, diamond for Media port, OA for Optical amplifier, OSC for Optical supervisory channel, and F for Filter. + +Diagram (b) showing management network relationships between digital and optical media subnetworks. It illustrates the flow of signals and management information between NE A, NE B, NE C, and NE D through various layers (X, Y, Z) and components like OTSi, OA, OSC, and F. A central amplifier site is also shown. + +(b) + +**Figure 6-4 – Example of management network relationships, (a) digital to digital subnetworks, (b) digital to media subnetworks** + +## 6.2 Equipment management architecture + +This clause provides an overview of the minimum functions that are required to support inter vendor NE management including single-ended maintenance of NEs within an x.MSN or between communicating peer NEs across a network interface. Single-ended maintenance is the ability to access remotely located NEs to perform maintenance functions (see clause 10 for the performance management applications). + +It should be noted that the management functions have been categorized according to the classifications given in [ITU-T X.700]. + +The equipment management function (EMF) provides the means through which a management and control system (MCS), such as an element management system (EMS), an SDN controller, and other managing entities, manage the network element function (NEF). Figure 6-5 illustrates the EMF components within the network element (NE). It must be noted that this illustration does not provide an exhaustive description of the functions that may be contained in an NEF (e.g., within atomic functions, EMF, MCF). If an NE contains an internal manager, this manager will be part of the EMF. + +The EMF interacts with the transport and synchronization layer atomic functions (AF) by exchanging management information (MI) across the management point (MP) reference points. See [ITU-T G.806] for more information on atomic functions and reference points. The EMF contains a number of functions that provide a data reduction mechanism on the information received across the MP reference points. + +The EMF includes functions such as date and time and the FCAPS (fault, configuration, accounting, performance and security) functions. The EMF contains a number of functions that provide a data reduction mechanism on the information received across the MP reference points. The outputs of these functions are available to the agent via the NE resources and MAFs that represent this information as managed objects. See Figure 6-5. The EMF provides event message processing, data storage and logging. The MAF processes the information provided to and by the NE resources. The agent converts internal MI signals into management application messages and vice versa. The agent responds to management application messages from the message communication function (MCF) by performing the appropriate operations on the managed objects in a management information base (MIB) (see [ITU-T X.701] and [ITU-T X.720] for more information on managed objects), as necessary. The MCF contains communications functions related to the outside world of the NEF (i.e., date and time, management plane (management via EMS), control plane (management via ASON connection controller), local craft terminal (management by user) and local alarms). + +The date and time functions keep track of the NE's date and time. The FCAPS functions that need date and time information, e.g., to time-stamp event reports, get this information from the date and time functions. + +![Figure 6-5 – Equipment management function process block diagram. The diagram shows the internal structure of a Network element function (NEF). On the left, 'Transport plane atomic functions' are shown as a vertical stack of triangles. An arrow labeled 'Management information' points from this stack to an 'MP reference point'. The central part is the 'Equipment management function (EMF)', which contains a 'Management application function (MAF)' with sub-functions: Date and time functions, Fault management, Configuration management, Account management, Performance management, and Security management. Below these is a 'Control plane function' with three green square icons and an 'Agent'. At the bottom is the 'Management information base (MIB)', represented as a cylinder containing five circles labeled 'MO' (Managed object). To the right of the EMF are interfaces: 'Date and time interface', 'Management plane interface', 'Control plane interface', and 'Local alarm interface'. These connect to the 'Message communication function (MCF)' on the far right. The MCF contains 'Date and time communication', 'Management plane communication', 'Control plane communication', and 'Local alarm communication'. Arrows show information flow: 'Date and time information' from Date and time functions to Date and time communication; 'Management plane information' from Management plane interface to Management plane communication; 'Control plane information' from Control plane interface to Control plane communication; and 'Local alarm information' from Local alarm interface to Local alarm communication. External connections on the far right include: 'From external time source' to Date and time communication; 'To/from management plane (e.g., EMS, peer NE)' to Management plane communication; 'To/from control plane (e.g., EMS, peer NE)' to Control plane communication; 'To/from local craft terminal' to Control plane communication; and 'To local alarms' from Local alarm communication. A legend at the bottom left shows a blue cylinder for 'Management information base' and a circle with 'MO' for 'Managed object'. The text 'G.7710-Y.1701(20)-Amd.1(22)_F6-5' is in the bottom right.](7133ccf78043568ca62ecbcd43628a4a_img.jpg) + +Figure 6-5 – Equipment management function process block diagram. The diagram shows the internal structure of a Network element function (NEF). On the left, 'Transport plane atomic functions' are shown as a vertical stack of triangles. An arrow labeled 'Management information' points from this stack to an 'MP reference point'. The central part is the 'Equipment management function (EMF)', which contains a 'Management application function (MAF)' with sub-functions: Date and time functions, Fault management, Configuration management, Account management, Performance management, and Security management. Below these is a 'Control plane function' with three green square icons and an 'Agent'. At the bottom is the 'Management information base (MIB)', represented as a cylinder containing five circles labeled 'MO' (Managed object). To the right of the EMF are interfaces: 'Date and time interface', 'Management plane interface', 'Control plane interface', and 'Local alarm interface'. These connect to the 'Message communication function (MCF)' on the far right. The MCF contains 'Date and time communication', 'Management plane communication', 'Control plane communication', and 'Local alarm communication'. Arrows show information flow: 'Date and time information' from Date and time functions to Date and time communication; 'Management plane information' from Management plane interface to Management plane communication; 'Control plane information' from Control plane interface to Control plane communication; and 'Local alarm information' from Local alarm interface to Local alarm communication. External connections on the far right include: 'From external time source' to Date and time communication; 'To/from management plane (e.g., EMS, peer NE)' to Management plane communication; 'To/from control plane (e.g., EMS, peer NE)' to Control plane communication; 'To/from local craft terminal' to Control plane communication; and 'To local alarms' from Local alarm communication. A legend at the bottom left shows a blue cylinder for 'Management information base' and a circle with 'MO' for 'Managed object'. The text 'G.7710-Y.1701(20)-Amd.1(22)\_F6-5' is in the bottom right. + +**Figure 6-5 – Equipment management function process block diagram** + +This Recommendation focuses on the EMF functions that affect the MI flows, originate the MI flows, or receive the MI flows. + +### 6.2.1 Management information base (MIB) + +All managed object instances within an NE shall be stored in a management information base (MIB). The following functions are required regarding the MIB: + +#### 1) *Get MIB of NE:* + +This function allows the OS to get the list of all object instances stored in the MIB of the NE. The list contains the objects and their relationships, i.e., connectivity pointers and containment relations (name binding). The function should be used by the OS to maintain its NEL-OS database. It is generally used for an NEL-OS database initialization at the network installation phase, or for a database recovery due to a discrepancy with the NE MIB after a network upgrade. + +#### 2) *Report NE MIB changes to the OS:* + +This function reports a new resource to the OS when it is inserted in the equipment, or to dismiss an entity when it is removed. When the hardware in the NE is changed by adding or removing a resource (e.g., port, card), the MIB in the OS has to be updated. + +The removing of a resource from an NE, and the deletion of the affected managed object instances shall be reported to the OS. + +## 6.3 Information flows over management points (MP) + +The information flows described in this clause are functional. The existence of these information flows in the equipment will depend on the functionality provided by the NE and the options selected. + +The information flow over the MP reference points that arises from anomalies and defects detected in the atomic functions of a NE is described in specific detail for each atomic function in the technology specific NE equipment Recommendations. + +The information flow over the MP reference points that arises from provisioning and reporting data is described in specific detail for each atomic function in the technology specific NE equipment Recommendations. + +The input information across an MP refers to the provisioning data that is passed from the EMF to the atomic functions. The output information across an MP refers to the reports passed to the EMF from the atomic functions. + +# 7 Fault management + +Fault management is a set of functions, which enables the detection, isolation and correction of abnormal operation of the telecommunication network and its environment. It provides facilities for the performance of the maintenance phases from [ITU-T M.20]. The quality assurance measurements for fault management include component measurements for reliability, availability and survivability (RAS). + +The six basic fault management application groups according to [ITU-T M.3400] are: + +## - *RAS quality assurance* + +RAS quality assurance establishes the reliability criteria that guides the design policy for redundant equipment (a responsibility of configuration management), and the policies of the other function groups in this area. + +## - *Alarm surveillance* + +A TMN provides the capability to monitor NE failures in near-real time. When such a failure occurs, an indication is made available by the NE. Based on this, a TMN determines the nature and severity of the fault. For example, it may determine the effect of the fault on the services supported by the faulty equipment. This can be accomplished in either of two ways: a database within a TMN may serve to interpret binary alarm indications from the NE, or if the NE has sufficient intelligence, it may transmit self-explanatory messages to a TMN. The first method requires little of the NE beyond a basic self-monitoring capability. The second method requires additionally that both the NE and a TMN support some type of message syntax that will allow the adequate description of fault conditions. + +Alarm information can be reported at the time of occurrence, and/or logged for future access. An alarm may also cause further management actions within the NE that lead to the generation of other fault management data. + +## - *Fault localization* + +When the initial failure information is insufficient for fault localization, it must be augmented with information obtained by additional failure localization routines. The routines can employ internal or external test systems and can be controlled by a TMN (see [ITU-T M.20]). + +## – *Fault correction* + +Fault correction transfers data concerning the repair of a fault and for the control of procedures that use redundant resources to replace equipment or facilities that have failed. + +## – *Testing* + +Testing can be carried out in one of two ways. In one case, a TMN directs a given NE to carry out analysis of circuit or equipment characteristics. Processing is executed entirely within the NE and the results are automatically reported to the TMN, either immediately or on a delayed basis. + +Another method is where the analysis is carried out within the TMN. In this case, the TMN merely requests that the NE provides access to the circuit or equipment of interest and no other messages are exchanged with the NE. + +## – *Trouble administration* + +Trouble administration transfers trouble reports originated by customers and trouble tickets originated by proactive failure detection checks. It supports action to investigate and clear the trouble and provides access to the status of services and the progress in clearing each trouble. + +The alarms are gathered, pre-processed and partly analysed in the NE for the purpose of maintenance, bringing-into-service, quality of service, reporting and thresholding. + +Clauses 7.1 and 7.2 specify the application groups necessary for fault management for transport network elements. + +## 7.1 RAS quality assurance + +Reliability, availability, and survivability (RAS) quality assurance is an application group for ensuring that a system or service can operate reliably and continuously under various conditions. It involves monitoring, managing and verifying the performance of a system or service using various techniques such as fault tolerance, redundancy, backup and recovery mechanisms, and disaster recovery planning. It enables the system or service to operate reliably, continuously and securely, even in the face of unexpected events or conditions. + +High reliability requires that optical communication systems or components reduce the probability of failure under specified conditions (e.g., environmental parameters such as temperature, humidity, vibration) and within a specified time. Specifically, during the design phase, the fault resistance of fibre links, optical devices (e.g., lasers, optical amplifiers, optical switches), and the overall system must meet high-reliability requirements. The optical devices need to minimize signal interruption or degradation caused by device aging, environmental interference (e.g., electromagnetic interference, temperature fluctuations), or physical damage (e.g., fibre bending). The optical fibres should enhance physical reliability to reduce damage and attenuation. During network operation and maintenance, network elements should be able to collect key performance indicators (KPIs) such as optical power, optical signal to noise ratio (OSNR) and bit error rate (BER) in real-time. These data could be used for early identification of potential faults. Network elements issue alarms when the parameters exceed the defined thresholds, thereby preventing persistent degradation from becoming a failure. + +High availability refers to the proportion of time an optical communication network can operate normally when needed. The calculation method for availability can be found in clause 10.1.5. To enhance high availability and reduce unavailability time, the key point is to shorten the failure recovery time, ensuring the system can quickly restore the service and maintain continuous operation after a problem occurs. Protection switching mechanisms are a typical method for improving availability. The protection switching mechanism is a typical method to improve availability. Through redundant path design, network elements can automatically switch from the working path to the protection path within 50 ms when a fault occurs, reducing service recovery time. Protection + +group information needs to be pre-configured onto the source and destination devices via the management and control (MC) system. In addition, methods such as online equipment maintenance and hot-swappable designs also enhance availability. Specifically, hot-swappable modules could be adopted on the equipment, allowing direct module replacement during the maintenance without shutting down the system, and remote online software upgrades for equipment can reduce the downtime caused by on-site manual operations. + +Strong survivability requires that an optical communication network maintains the operation of critical services (e.g., emergency communications, critical data transmission) even when subjected to sudden disturbances (e.g., natural disasters, malicious attacks, large-scale equipment failures). It allows non-critical services to degrade but ensures that critical services remain uninterrupted. Specifically, transport networks can use the mesh topology and multi-path redundancy to effectively enhance survivability. In a mesh topology, each node connects directly to multiple nodes, forming a network structure with optional multiple paths. When a link or node fails due to a disaster, equipment can use dynamic routing protocols such as generalized multi-protocol label switching (GMPLS) to recalculate and switch to other available paths within hundreds of milliseconds, ensuring that critical services remain uninterrupted. Geographically diverse backup links (e.g., cross-regional backup optical cables) can be pre-planned. If an entire regional network fails, critical services are automatically switched to the backup region. Service priority mechanisms can further ensure that during bandwidth-constrained recovery phases, critical services are guaranteed first, while non-core services are suspended. Additionally, equipment can be reinforced with hardened cabinets and dual power inputs in the installation to withstand harsh environments (e.g., high temperature, vibration) and reduce failures caused by physical damage. + +High reliability, high availability, and strong survivability together guarantee the stable, continuous, and secure operation of optical communication systems in complex environments. + +## **7.2 Alarm surveillance** + +Alarms are gathered, pre-processed and partly analysed in the NE for the purpose of maintenance, bringing-into-service, quality of service, reporting and thresholding. Clauses 7.2.1 and 7.2.2 specify the applications necessary for alarm surveillance for transport network elements. + +### **7.2.1 Alarm surveillance applications** + +#### **7.2.1.1 Supervision** + +The supervision process describes the way in which the actual occurrence of a disturbance or fault is analysed with the purpose of providing an appropriate indication of performance and/or detected fault condition to maintenance personnel. The supervision philosophy is based on the concepts underlying the architectural model of [ITU-T G.800] (for unified functional architecture of transport network), [ITU-T G.807] (for media layer networks) and [ITU-T G.805] (for connection-oriented networks), and the alarm reporting function of [ITU-T X.733]. + +The five basic supervision categories are related to transmission, quality of service, processing, equipment and environment. These supervision processes are able to declare fault causes, which need further validation before the appropriate alarm is reported. + +The NE shall indicate to the OS when a TP is no longer able to supervise the signal (e.g., implementing equipment has a fault or loss of power). + +##### **7.2.1.1.1 Transmission supervision** + +Transmission supervision processes are concerned with the management of the transmission resources in the network, and are only interested in the functionality that is being provided by an NE. It requires a functional representation of an NE that is implementation independent. + +Most functions process the signals to detect the occurrence of certain characteristics and provide performance information or alarm conditions based on these characteristics. Therefore, transmission supervision processing provides information on the external interface signals that are processed by an NE. + +Transmission supervision comprises: + +- Continuity supervision for the detection of a broken connection, e.g., a cable cut or open matrix. This condition is determined by the sink function at the arrival of "no signal" (LOS), the "unequipped indication" (UNEQ) or the "open connection indication" (OCI). In case of an open matrix, the source function sends the UNEQ or OCI indication. +- Connectivity supervision for the detection of a misconnection, e.g., a misconnected cable or an incorrect matrix connection. This condition is determined by the sink function at the arrival of an unexpected value of the trail trace identifier (trace identifier mismatch (TIM)). The source function sends the agreed TTI value. +- Signal quality supervision for the detection of degraded performance (DEG). This condition is determined by the sink function, e.g., based on the calculation of the error detection code (EDC) violations. The source function sends the EDC. +- Payload type supervision for the detection of incompatible adaptation functions at the ends of trails, e.g., the source uses bit synchronous mapping while the sink expects byte synchronous mapping. This condition is determined by the sink function at the arrival of an unexpected value of the path signal label (payload type mismatch (PLM)). The source function sends the PSL value that corresponds with the mapping. +- Multiplex structure supervision for the detection of a wrong payload structure. +- Alignment supervision for the detection of wrong frame alignment, i.e., the receiving end considers the start of the frame at the wrong position. This condition is determined by the sink function at the arrival of a wrong frame alignment signal (loss of frame (LOF); loss of multiframe (LOM)) at the considered frame start position. The source function sends the FAS at a specified position in the frame. +- Protocol supervision for the detection of failures in the sequence of a protocol exchange, e.g., a failure in the automatic protection switching protocol. This condition is determined by the sink function at the arrival of an unexpected (i.e., out of sequence) protocol message, after which the sink function declares a failure of protocol (FOP) defect. +- Single ended supervision to be able to monitor the trail status in both directions at a single location, e.g., to monitor the occurrence of defects, detected at both ends of the trail. These occurrences (backward failures) are monitored at the trail termination or connection points by reading the remote defect indication (RDI) or backward defect indication (BDI). The source function sends the RDI or BDI. +- Alarm suppression is considered as part of the transmission supervision process. Its aim is not only to alarm the root cause, but also to suppress resulting alarms in the detecting NE and all downstream NEs. This condition (forward failure) is determined by the sink functions at the arrival of an alarm indication signal (AIS) or forward defect indication (FDI). The source function sends the AIS or FDI. + +NOTE 1 – A misconnection due to an open matrix could be detected by the continuity supervision process, rather than by the connectivity supervision process. + +NOTE 2 – An inconsistent payload structure or inconsistent payload type could be detected by the alignment supervision process, rather than by the multiplex supervision process or the payload type supervision process. + +Transmission failures can be subdivided between primary failures and secondary/consequential failures. Primary failures, in general, indicate the cause of the fault, e.g., a broken cable or a misconnection. The primary failure reports indicate the fault location and initiate a repair action. + +Secondary or consequential failures, in general, indicate whether the service is up or down. They are generated to suppress alarms, e.g., AIS, SSF, FDI. + +Transmission failures can be associated with the three types of transport atomic functions: termination, adaptation and connection. Table 7-1 gives examples. + +**Table 7-1 – Atomic function associated transmission failure list** + +| | Termination sink | Adaptation sink | Connection | +|-------------------------------------|--------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------|----------------------------------------------------| +| Primary failures | Continuity failure, e.g., loss of signal (LOS), loss of continuity (LOC), unequipped (UNEQ), open connection indication (OCI). | Framing failure, e.g., loss of frame (LOF), loss of multiframe (LOM), loss of pointer (LOP). | Protocol failure, e.g., failure of protocol (FOP). | +| | Connectivity failure, e.g., trace identifier mismatch (TIM). | Payload type failure, e.g., payload mismatch (PLM). | | +| | Degradation failure, e.g., signal degraded (DEG). | Payload structure failure, e.g., multiplex structure identifier mismatch (MSIM). | | +| | Connection monitoring source failure, e.g., loss of tandem connection (LTC). | | | +| Secondary or consequential failures | Forward failure, e.g., alarm indication signal (AIS), forward defect indication (FDI), server signal fail (SSF). | Forward failure, e.g., alarm indication signal (AIS), forward defect indication (FDI), server signal fail (SSF). | | +| | Backward failure, e.g., backward/remote/outgoing defect indication (BDI/RDI/ODI). | | | + +Details of transmission supervision are described in clause 6 of [ITU-T G.806]. + +##### 7.2.1.1.2 Quality of service supervision + +Quality of service supervision is principally associated with degradation in the performance. Annex A of [ITU-T X.733] lists the following probable causes in this category: excessive response time, exceeded queue size, reduced bandwidth, excessive retransmission rate, threshold crossed, degraded performance, congestion, resource at or nearing capacity. This Recommendation elaborates on degraded performance and threshold crossings only. Note that signal quality supervision is, for historical reasons, part of transmission supervision. + +##### 7.2.1.1.3 Processing supervision + +Processing supervision is principally associated with a software or software processing fault. Annex A of [ITU-T X.733] lists the following probable causes in this category: storage capacity problem, version mismatch, corrupt data, CPU cycles limit exceeded, software error, software program error, software program abnormally terminated, file error, out of memory, underlying resource unavailable, application subsystem failure, configuration of customization error. As these probable causes are implementation-specific and vendor-specific, they are not subject to standardization. Note that protocol supervision is, for historical reasons, part of transmission supervision. + +##### 7.2.1.1.4 Hardware supervision + +Equipment supervision processing is concerned with the fault localization and repair of the equipment itself. Its purpose is to answer the classic questions: "who to send where to repair what?" It does not require knowledge of the transmission network. Annex A of [ITU-T X.733] lists the following probable causes in this category: power problem, timing problem, processor problem, dataset or modem error, multiplexer problem, receiver or transmitter failure, input-output device error, equipment malfunction, adapter error. In general, within the scope of this Recommendation, equipment supervision comprises the supervision of interchangeable and non-interchangeable units and cables. As these probable causes are implementation-specific and vendor-specific, they are not subject to standardization. + +##### 7.2.1.1.5 Environmental supervision + +Environmental supervision is principally associated with a condition related to ambient conditions within an enclosure in which the equipment resides. Annex A of [ITU-T X.733] lists the following probable causes in this category: temperature unacceptable, humidity unacceptable, heating/ventilation/cooling system problem, enclosure door open, pump failure, etc. In general, within the scope of this Recommendation, environmental supervision comprises the supervision of sensor contacts, known as miscellaneous discrete inputs. As these probable causes are implementation-specific and vendor-specific, they are not subject to standardization. + +#### 7.2.1.2 Validation + +A fault cause indicates a limited interruption of the required function. A fault cause is not reported to maintenance personnel because it could exist for a very short time only. Some of these events however are summed up in the performance monitoring process, and when this sum exceeds a certain value, a threshold report can be generated (see clause 10.1.7). + +When the fault cause lasts long enough, an inability to perform the required function arises. This failure condition is subject to be alarmed to maintenance personnel because corrective action might be required. Conversely, when the fault cause ceases to be declared after a certain time, the failure condition must disappear. + +Validation is concerned with the integration of fault causes into failures. As this integration is only time-based, the related function is called fault cause persistency (see clause 7.2.2.1). + +#### 7.2.1.3 Alarm handling + +##### 7.2.1.3.1 Severity assignment + +Failures may have been categorized to indicate the severity or urgency of the fault. [ITU-T M.20] and [ITU-T X.733] define different, though comparable categories. [ITU-T M.3100] has extended the [ITU-T X.733] list. Table 7-2 summarizes these categories. + +**Table 7-2 – Severity categories** + +| M.20 | X.733 | M.3100 | Description | +|----------------------------|----------|----------|-----------------------------------------------------------------------------------------------------------------------------| +| Prompt maintenance alarm | Critical | Critical | Indication for a service-affecting condition. Immediate corrective action is required. | +| | Major | Major | Indication for a service-affecting condition. Urgent corrective action is required. | +| Deferred maintenance alarm | Minor | Minor | Indication for a non-service-affecting condition. Corrective action should be taken in order to prevent more serious fault. | + +**Table 7-2 – Severity categories** + +| M.20 | X.733 | M.3100 | Description | +|-------------------------------|--------------|---------------|----------------------------------------------------------------------------------------------------| +| Maintenance event information | Warning | Warning | Indication for a potential or impending service-affecting fault. Further diagnosis should be made. | +| – | – | Not alarmed | Indication to indefinitely suppress reporting. | + +NOTE 1 – The severities "cleared" and "indeterminate" defined by [ITU-T X.733] are not included in Table 7-2, as it is assumed that these are not to be used to assign a failure. + +NOTE 2 – The severities, defined by [ITU-T M.20], are mainly used for presentation by LEDs. The severities, defined by [ITU-T X.733] reflect the underlying management messages. + +For maintenance personnel, it is important to know the urgency of the required action. The severity assignment function (see clause 7.2.2.2) has the capability to assign a severity to a failure. + +The severity "Not alarmed" suppresses the reporting of a failure per managed entity and per event or failure type. + +The severity for each failure instance may be provisioned to a value other than the default. For example, when no trail trace identifiers are used in the network, the primary failure TIM may be provisioned to "Not alarmed". Another example is to provision the secondary failure AIS to "Critical" at the ingress of the network. In this way, the operator is aware of whether or not the customer signal carries traffic. + +##### 7.2.1.3.2 Alarm reporting control + +The following alarm reporting control (ARC) states may be specified for a managed entity: + +- ALM            Alarm reporting; alarm reporting is turned on. +- NALM        No alarm reporting; alarm reporting is turned off. +- NALM-CD   No alarm reporting, countdown; this is a sub-state of NALM-QI and performs the persistence timing countdown function when the managed entity is qualified problem free. +- NALM-NR   No alarm reporting, not ready; this is a sub-state of NALM-QI and performs a wait function until the managed entity is qualified problem free. +- NALM-QI    No alarm reporting, qualified inhibit; alarm reporting is turned off until the managed entity is qualified problem free for a specified persistence interval. +- NALM-TI    No alarm reporting, timed inhibit; alarm reporting is turned off for a specified timed interval. + +ARC supports an automatic in-service provisioning capability. Alarm reporting may be turned off (using NALM, NALM-TI, or NALM-QI) on a per managed entity basis to allow sufficient time for customer service testing and other maintenance activities in an "alarm free" state. Once a managed entity is ready, alarm reporting is automatically turned on (to ALM). The managed entity may be automatically turned on either by using NALM-TI or NALM-QI and allowing the resource to transition out automatically, or by invoking first the NALM state from an EMS and, when maintenance activity is done, invoking the ALM state. This later automation is carried out by the EMS. For further details relating to ARC, see [ITU-T M.3100]. + +It is critical during maintenance activities that alarm monitoring of the managed entity continues to occur. By maintaining managed entity monitoring, technicians can retrieve alarm and performance information to troubleshoot during the provisioning or maintenance process, or later during a post-mortem on a provisioning task gone awry. ARC addresses this need. + +ARC includes a persistence interval before reporting begins in recognition of the fact that during provisioning and during customer turn-up activities, the managed entity may become available briefly, only to be lost again as the service configuration is changed. + +ARC applies to all managed entities that provide alarm reporting and especially to all managed resources autonomously provisioned by the managed system/managed application, and all managed entities that may be pre-provisioned via a management interface. + +By activating alarm reporting control, the technicians and OS systems will not be flooded with unnecessary work items during operations activities such as service activation and the customer's service turn-up activities. This will reduce maintenance costs and improve the operation and maintenance of these systems. + +##### 7.2.1.3.3 Reportable failures + +Figure 7-1 outlines a managed entity with its associated failures. In this general case, the managed entity, e.g., a termination sink function, can declare a number of primary and secondary failures. The reporting of these failures is controlled by two report options. The first option, alarm severity assignment, when "Not alarmed" indefinitely suppresses reporting for that failure. The second option, alarm reporting control (ARC), temporarily controls the reporting of the failure by means of the ARC mode. + +![Diagram of a managed entity with associated failures.](5478f70a6cef3e5672b2b22d28830cfb_img.jpg) + +The diagram shows a large circle representing a 'Managed entity reporting controlled by ARC mode'. Inside this circle are two smaller circles. The top smaller circle contains five small circles and is labeled 'Primary failures'. The bottom smaller circle contains three small circles and is labeled 'Secondary failures'. An arrow from the text 'Primary and secondary failure reporting controlled by alarm severity' points to both the top and bottom smaller circles. A small code 'G.7710-Y.1701(20)-Amd.1(22)\_F7-1' is located at the bottom right of the diagram. + +Diagram of a managed entity with associated failures. + +**Figure 7-1 – Managed entity with associated failures** + +##### 7.2.1.3.4 Alarm reporting + +Alarm surveillance is concerned with the detection and reporting of relevant events and conditions, which occur in the network. In a network, events and conditions detected within the equipment and incoming signals should be reportable. In addition, a number of events external to the equipment should also be reportable. Alarms are indications that are automatically generated by an NE as a result of the declaration of a failure. The NE shall have the ability to accept OS directions related to which events and conditions generate autonomous reports and which shall be reported on request. + +The following alarm-related functions shall be supported: + +- 1) autonomous reporting of alarms; +- 2) request for reporting of all alarms; +- 3) reporting of all alarms; +- 4) allowance or inhibition of autonomous alarm reporting; +- 5) reporting on request status of allow or inhibit alarm reporting; +- 6) control of the trail termination point mode and port mode; + +NOTE – Applicable only to SDH and PDH and superseded for new development (e.g., OTN). See Appendix III. + +- 7) reporting of protection switch events. + +###### **7.2.1.3.4.1 Local reporting** + +Local reporting is concerned with alarming by means of audible and visual indicators near the failed equipment. These bells and lamps could be organized in a certain hierarchy, so that maintenance personnel are able to follow the trail of lights (or bells) to locate the failed equipment. Based on the indicator value (e.g., the sound, the colour and flashing of the light, the message on a display), maintenance personnel are able to execute the appropriate corrective action. + +Local reports include: + +- unit alarms; +- network element alarms; +- station alarms. + +###### **7.2.1.3.4.2 TMN reporting** + +TMN reporting is concerned with reporting to an OS. These reports are either autonomous reports (notifications) or reports on request by maintenance personnel. + +TMN reports include: + +- TMN alarm event notifications +- alarm log +- alarm synchronization +- current problem list +- alarm status +- operational state. + +##### **7.2.1.3.5 Alarm correlation** + +The correlation analysis between different alarms generated in an NE can also be included in alarm handling. The correlation analysis is concerned with the potential correlation between different alarms in an NE. Its purpose is to identify the root alarms and their derived alarms, including the correlation analysis of the alarms on the same board or between different boards in an NE. Expert rules or artificial intelligence AI/machine learning (ML) algorithms may be used to assist the correlation analysis and information other than alarms, e.g., the topology and inventory information etc. could also be raw data for this analysis. Alarm reporting could be further controlled based on the operator policy, including only reporting the root alarms to reduce the number of alarms or reporting the alarms with the correlation information for further analysis within the MC system. The reporting policies could be pre-configured. The alarm correlation analysis function support to be enabled or disabled by configuration. + +### **7.2.2 Alarm surveillance functions** + +Figure 7-2 contains a functional model of fault management inside the EMF. This model is consistent with the alarm flow functional model, specified in [ITU-T M.3100]. It must be noted that this figure does not address configuration aspects relating to fault management, the full ARC functional model, nor does it define where all possible event report parameters get assigned. This figure is only intended to illustrate which well-known functions are impacted by ARC and which are not, and to provide a generalized alarm flow view. + +Specifications of the functions are given in subsequent clauses. + +![Figure 7-2: Fault management inside the EMF. This block diagram shows the flow of fault information through various functions within the EMF. Inputs include 'Fault cause' (MI_cZZZ) and 'Failure' (fZZZ-value) from 'Non-atomic functions'. The 'Fault management' block contains 'PRS', 'SEV', 'ARC', 'REP', 'TEP', 'UNA', 'NEA', 'STA', 'ASY', 'LOG', 'TAN', 'CPL', 'AST', and 'OPS'. Data flows include 'Alarm severity assignment profile', 'ARC information', and 'Reportable failure'. Output functions include 'Management applications function' (UNA, NEA, STA, ASY, LOG, TAN) and 'Date and time functions' (CPL, AST, OPS).](f9c64800d9bace9b4315646d1057be3c_img.jpg) + +The diagram illustrates the internal architecture of the EMF's fault management. It shows a sequence of processing steps: PRS (Fault cause persistence), SEV (Severity), ARC (Alarm Reporting Control), REP (Report), and TEP (Temporary Event Persistence). Each step has associated data parameters like MI\_cZZZ, fZZZ-value, fZZZ-severity, and fZZZ-arc. The REP function feeds into several output functions: UNA (Unit alarms), NEA (Network element alarms), STA (Station alarms), ASY (Alarm synchronization), LOG (Query), and TAN (TMN alarm event notifications). The REP function also feeds into a 'Related alarm list' which includes CPL (Current problem list), AST (Alarm status), and OPS (Operational state). Control inputs from 'Non-atomic functions' include NE-RTC, and configuration inputs include 'Alarm severity assignment profile' and 'ARC information'. The entire 'Fault management' block is categorized as an 'Atomic function'. + +Figure 7-2: Fault management inside the EMF. This block diagram shows the flow of fault information through various functions within the EMF. Inputs include 'Fault cause' (MI\_cZZZ) and 'Failure' (fZZZ-value) from 'Non-atomic functions'. The 'Fault management' block contains 'PRS', 'SEV', 'ARC', 'REP', 'TEP', 'UNA', 'NEA', 'STA', 'ASY', 'LOG', 'TAN', 'CPL', 'AST', and 'OPS'. Data flows include 'Alarm severity assignment profile', 'ARC information', and 'Reportable failure'. Output functions include 'Management applications function' (UNA, NEA, STA, ASY, LOG, TAN) and 'Date and time functions' (CPL, AST, OPS). + +NOTE – Alarms from non-atomic functions indicate that the alarms do not come from atomic functions defined in the equipment Recommendations and may be from hardware, software and the environment. + +**Figure 7-2 – Fault management inside the EMF** + +#### 7.2.2.1 Fault cause persistency function – PRS + +The EMF within the NE performs a persistency check on the fault causes before it declares that a fault cause is a failure. + +The defect correlations provide a data reduction mechanism for the information on fault and performance monitoring primitives presented at the MP reference points. + +The fault cause persistency function will provide a persistency check on the fault causes (that are reported across the MP reference points) before it declares that a fault cause is a failure. In addition to the transmission failures, hardware failures with signal transfer interruption are also reported at the input of the fault cause function for further processing. See Figure 7-3. + +**Symbol:** + +![Figure 7-3: Fault cause persistency function. This diagram shows the PRS function block. An input labeled 'MI_cZZZ (Fault cause)' enters the PRS block from the left through an 'MP' (Management Point) reference point. An input labeled 'NE-RTC' enters the PRS block from the bottom. The output of the PRS block is labeled 'fZZZ-value (Failure)'.](446100c084b94817a19c319fa776b412_img.jpg) + +The diagram shows the PRS function as a processing block. It takes a 'Fault cause' (MI\_cZZZ) as input at the 'MP' reference point. It also receives an 'NE-RTC' (Network Element Real Time Clock) input. The output is a 'Failure' (fZZZ-value). + +Figure 7-3: Fault cause persistency function. This diagram shows the PRS function block. An input labeled 'MI\_cZZZ (Fault cause)' enters the PRS block from the left through an 'MP' (Management Point) reference point. An input labeled 'NE-RTC' enters the PRS block from the bottom. The output of the PRS block is labeled 'fZZZ-value (Failure)'. + +**Figure 7-3 – Fault cause persistency function** + +##### **Interfaces:** + +**Table 7-3 – Fault cause persistency input and output signals** + +| Input(s) | Output(s) | +|-------------------|------------| +| MI_cZZZ
NE-RTC | fZZZ-value | + +##### **Processes:** + +The fault cause persistency function is responsible for the integration of fault causes MI\_cZZZ-value into failures fZZZ-value. + +A transmission failure (fZZZ-value) shall be declared if the fault cause persists continuously for $2.5 \pm 0.5$ s. The failure shall be cleared if the fault cause is absent continuously for $10 \pm 0.5$ s. + +The failure declaration and clearing shall be time-stamped. For declaration, the time-stamp shall indicate the time at which the fault cause is activated at the input of the PRS. For clearing, the time-stamp shall indicate the time at which the fault cause is deactivated at the input of the PRS. + +The fZZZ-value includes the identification of the managed entity and its location, an indication whether the failure has been raised or cleared, and a time-stamp of this event. + +#### **7.2.2.2 Severity assignment function – SEV** + +##### **Symbol:** + +![Block diagram of the SEV (Severity assignment function).](3db5d62ad46e33647ec2b1ad6d2703bb_img.jpg) + +``` + +graph LR + A[fZZZ-value] --> SEV[SEV] + B[Alarm severity assignment profile] --> SEV + SEV --> C[fZZZ-value] + SEV --> D[fZZZ-severity] + +``` + +The diagram shows a rectangular block labeled 'SEV'. A horizontal arrow labeled 'fZZZ-value' enters the block from the left. A vertical arrow labeled 'Alarm severity assignment profile' enters the block from the top. Two horizontal arrows exit the block to the right, labeled 'fZZZ-value' and 'fZZZ-severity' respectively. Below the diagram is the reference code: G.7710-Y.1701(20)-Amd.1(22)\_F7-4. + +Block diagram of the SEV (Severity assignment function). + +**Figure 7-4 – Severity assignment function** + +##### **Interfaces:** + +**Table 7-4 – Severity assignment input and output signals** + +| Input(s) | Output(s) | +|-------------------------------------------------|-----------------------------| +| fZZZ-value
Alarm severity assignment profile | fZZZ-value
fZZZ-severity | + +##### **Processes:** + +The severity assignment function is responsible for assigning a value to the fZZZ-severity variable. + +The assignment shall be possible per managed entity and is based on the alarm severity assignment profile. + +The severity shall be expressed according to the specification in [ITU-T M.3100]: + +- Critical, major, minor, warning, not alarmed. + +The failure fZZZ-value accompanied with the assigned severity fZZZ-severity shall become available at the output. + +#### 7.2.2.3 Alarm reporting control function – ARC + +The ARC function allows a management system to control the alarm reporting on a per-managed entity basis as defined in [ITU-T M.3100]. + +The ARC states that may be specified for a managed entity are defined in clause 7.2.1.3.2: + +- the ALM state is required for all managed entities that can detect alarms; +- in addition, at least one of the states: NALM, NALM-TI or NALM-QI must be supported; +- if NALM-QI is supported, then NALM-NR is required, and NALM-CD is optional. + +When an entity is put in the ARC state of NALM-QI, alarm reporting for the entity is turned off until the managed entity is free of all the failures specified in the ARC list. + +**Symbol:** + +![Diagram of the Alarm Reporting Control (ARC) function. A central box labeled 'ARC' has an input arrow from the left with labels 'fZZZ-value' and 'fZZZ-severity'. An output arrow points to the right with labels 'fZZZ-value', 'fZZZ-severity', and 'fZZZ-arc'. A vertical arrow points down to the 'ARC' box from above with labels 'ARC state', 'ARC list', 'TI-time', and 'QI-time'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-5'.](fb18a83d10ebdad8e3e5ea2e86b36136_img.jpg) + +Diagram of the Alarm Reporting Control (ARC) function. A central box labeled 'ARC' has an input arrow from the left with labels 'fZZZ-value' and 'fZZZ-severity'. An output arrow points to the right with labels 'fZZZ-value', 'fZZZ-severity', and 'fZZZ-arc'. A vertical arrow points down to the 'ARC' box from above with labels 'ARC state', 'ARC list', 'TI-time', and 'QI-time'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-5'. + +**Figure 7-5 – Alarm reporting control** + +**Interfaces:** + +**Table 7-5 – ARC input and output signals** + +| Input(s) | Output(s) | +|----------------------------------------------------------------------------|-----------------------------------------| +| fZZZ-value
fZZZ-severity
ARC state
ARC list
TI-time
QI-time | fZZZ-value
fZZZ-severity
fZZZ-arc | + +**Processes:** + +The ARC function is responsible for assigning a value to the fZZZ-arc variable. + +The assignment shall be possible per managed entity and is based on the ARC information. + +The fZZZ-arc value shall be "reported" when the ARC information specifies the probable cause to be "reported". + +The fZZZ-arc value shall be "not reported" when the ARC information specifies the probable cause to be "not reported". + +The failure value and severity accompanied with the assigned alarm status fZZZ-arc shall become available at the output. + +Note that ARC information includes the ARC state (whether or not the managed entity is ARCing any failures) and the list of problems that has been requested to be suppressed. If the ARC state is in any state but ALM, the list of problems to be suppressed needs to be evaluated to determine whether or not the failure can be reported. + +The ARC shall be implemented according to the specification in [ITU-T M.3100]. + +#### 7.2.2.4 Reportable failure function – REP + +**Symbol:** + +![Diagram of the Reportable failure function (REP) block. Inputs from the top are ALC rule, ALC enable, ALC reporting policy, and ALC time interval. Input from the left are fZZZ-value, fZZZ-severity, and fZZZ-arc. The block is labeled 'REP'. Output to the right are rZZZ-value and rZZZ-severity. Output to the bottom is Related alarm list. A reference G.7710(25) is shown at the bottom right.](6629e8a87e7552e2454b7c3e9f6d73a0_img.jpg) + +Diagram of the Reportable failure function (REP) block. Inputs from the top are ALC rule, ALC enable, ALC reporting policy, and ALC time interval. Input from the left are fZZZ-value, fZZZ-severity, and fZZZ-arc. The block is labeled 'REP'. Output to the right are rZZZ-value and rZZZ-severity. Output to the bottom is Related alarm list. A reference G.7710(25) is shown at the bottom right. + +**Figure 7-6 – Reportable failure function** + +**Interfaces:** + +**Table 7-6 – Reportable failure input and output signals** + +| Input(s) | Output(s) | +|----------------------------------------------------------------------------------------------------------------|---------------------------------------------------| +| fZZZ-value
fZZZ-severity
fZZZ-arc
ALC rule
ALC enable
ALC reporting policy
ALC time interval | rZZZ-value
rZZZ-severity
Related alarm list | + +**Processes:** + +The reportable failure function acts as a filter responsible for forwarding only the probable causes of alarms that have been identified as reportable. The REP could also support the alarm correlation (ALC) function, which is responsible for determining the root alarms with their related alarms in NE. Alarm correlation shall be based on the input of ALC configuration and alarms. + +If the failure is not being controlled by ARC or has an alarm severity assignment of "Not alarmed", and if the ALC is not enabled, the failure's value and severity shall become available at the output as rZZZ-value and rZZZ-severity. If the failure is not being controlled by ARC, or has an alarm severity assignment of "Not alarmed", and if ALC is enabled in REP, when the ALC reporting policy is "Not reported", only the rZZZ-value and rZZZ-severity of the root alarms will be available at the output, and when ALC reporting policy is "Reported", the rZZZ value and rZZZ-severity of each root alarm and its related alarms should be available at the output. Otherwise, neither rZZZ-value nor rZZZ-severity shall become available at the output. + +- ALC rule: an input signal about alarm correlation rules, such as slot alarm suppresses port alarm, server layer alarm suppresses client layer alarm, and alarm A suppresses alarm B, etc. +- ALC enable: an input signal and if it is enabled, REP should perform the alarm correlation function for all input alarms. Otherwise, the input alarms will be available at the output. +- ALC reporting policy: an input signal which takes effect when ALC is enabled. If the value is "Not reported", it means only root alarms shall be reported. If the value is "Reported", it means the root alarms and their corresponding related alarm list shall be reported. +- ALC time interval: an input signal that means that the alarm in the time interval will be input for alarm correlation. This could be optional. + +- Related alarm list: an output signal representing the related alarms associated with each root alarm. When the ALC is enabled and the ALC reporting policy is "Reported", the rZZZ value and rZZZ-severity of each root alarm and the related alarm list associated to each root alarm should be reported, the rZZZ value and rZZZ-severity will go through the following TEP, STA and NEA functions, and meanwhile the related alarm list associated to each root alarm will go directly to the MAF. + +#### 7.2.2.5 Unit alarms function – UNA + +Symbol: + +![Diagram of the Unit alarms function (UNA). Inputs: fZZZ-value, fZZZ-severity, fZZZ-arc. Output: Unit alarms. Reference: G.7710-Y.1701(20)-Amd.1(22)_F7-7](9f6dec4d4e9fde40bce018861ef1278e_img.jpg) + +``` + +graph LR + Inputs["fZZZ-value +fZZZ-severity +fZZZ-arc"] --> UNA[UNA] + UNA --> Output["Unit alarms"] + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F7-7 + +Diagram of the Unit alarms function (UNA). Inputs: fZZZ-value, fZZZ-severity, fZZZ-arc. Output: Unit alarms. Reference: G.7710-Y.1701(20)-Amd.1(22)\_F7-7 + +Figure 7-7 – Unit alarms function + +Interfaces: + +Table 7-7 – Unit alarms input and output signals + +| Input(s) | Output(s) | +|-----------------------------------------|-------------| +| fZZZ-value
fZZZ-severity
fZZZ-arc | Unit alarms | + +Processes: + +The unit alarms function is responsible for determining whether or not unit audible/visual indicators need to be updated. + +Effect of the alarm status upon audible/visual indicators is left undefined in this Recommendation. It is only illustrated here to show that alarm information is forwarded to this function for application-specific processing. + +#### 7.2.2.6 Network element alarms function – NEA + +Symbol: + +![Diagram of the Network element alarms function (NEA). Inputs: rZZZ-value, rZZZ-severity. Output: Network element alarms. Reference: G.7710-Y.1701(20)-Amd.1(22)_F7-8](00942e7d6db56fd4fbd5f45bdbad7fdb_img.jpg) + +``` + +graph LR + Inputs["rZZZ-value +rZZZ-severity"] --> NEA[NEA] + NEA --> Output["Network element alarms"] + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F7-8 + +Diagram of the Network element alarms function (NEA). Inputs: rZZZ-value, rZZZ-severity. Output: Network element alarms. Reference: G.7710-Y.1701(20)-Amd.1(22)\_F7-8 + +Figure 7-8 – Network element alarms function + +Interfaces: + +Table 7-8 – Network element alarms input and output signals + +| Input(s) | Output(s) | +|-----------------------------|------------------------| +| rZZZ-value
rZZZ-severity | Network element alarms | + +##### **Processes:** + +The network element alarms function is responsible for determining whether or not aggregate audible/visual indicators need to be updated. + +#### **7.2.2.7 Station alarms function – STA** + +##### **Symbol:** + +![Block diagram of the Station alarms function (STA). An input arrow on the left points to a box labeled 'STA', with 'rZZZ-value' and 'rZZZ-severity' written above it. An output arrow on the right points away from the box, labeled 'Station alarms'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-9'.](f5deee2f3301ee351c4008283ffafbb3_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F7-9 + +Block diagram of the Station alarms function (STA). An input arrow on the left points to a box labeled 'STA', with 'rZZZ-value' and 'rZZZ-severity' written above it. An output arrow on the right points away from the box, labeled 'Station alarms'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-9'. + +**Figure 7-9 – Station alarms function** + +##### **Interfaces:** + +**Table 7-9 – Station alarms input and output signals** + +| Input(s) | Output(s) | +|-----------------------------|----------------| +| rZZZ-value
rZZZ-severity | Station alarms | + +##### **Processes:** + +The station alarms function is responsible for determining whether or not aggregate station audible/visual indicators need to be updated. + +#### **7.2.2.8 TMN event pre-processing function – TEP** + +##### **Symbol:** + +![Block diagram of the TMN event pre-processing function (TEP). An input arrow on the left points to a box labeled 'TEP', with 'rZZZ-value' and 'rZZZ-severity' written above it. An output arrow on the right points away from the box, with 'rZZZ-value' and 'rZZZ-severity' written above it. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-10'.](6757222e979ee95c44354a897c5cc1c1_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F7-10 + +Block diagram of the TMN event pre-processing function (TEP). An input arrow on the left points to a box labeled 'TEP', with 'rZZZ-value' and 'rZZZ-severity' written above it. An output arrow on the right points away from the box, with 'rZZZ-value' and 'rZZZ-severity' written above it. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-10'. + +**Figure 7-10 – TMN event pre-processing function** + +##### **Interfaces:** + +**Table 7-10 – TMN event pre-processing input and output signals** + +| Input(s) | Output(s) | +|-----------------------------|-----------------------------| +| rZZZ-value
rZZZ-severity | rZZZ-value
rZZZ-severity | + +##### **Processes:** + +The TMN event pre-processing function (see [ITU-T X.734]) adds information such as correlated notifications. Generally, it adds information that is not determined or possible to determine by the object, but across multiple objects. + +#### 7.2.2.9 Alarm synchronization function – ASY + +**Symbol:** + +![Symbol diagram for the Alarm synchronization function (ASY). An input signal labeled 'rZZZ-value' and 'rZZZ-severity' enters a box labeled 'ASY' from the left. An output signal labeled 'Alarm synchronization' exits the box to the right. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-11'.](95e259e8cb3519025066052af263f8c0_img.jpg) + +Symbol diagram for the Alarm synchronization function (ASY). An input signal labeled 'rZZZ-value' and 'rZZZ-severity' enters a box labeled 'ASY' from the left. An output signal labeled 'Alarm synchronization' exits the box to the right. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-11'. + +**Figure 7-11 – Alarm synchronization function** + +**Interfaces:** + +**Table 7-11 – Alarm synchronization input and output signals** + +| Input(s) | Output(s) | +|-----------------------------|-----------------------| +| rZZZ-value
rZZZ-severity | Alarm synchronization | + +**Processes:** + +The alarm synchronization function is responsible for storing all current reportable alarm information. Storing means to support functions such as enhanced event control (see [ITU-T Q.821]). + +#### 7.2.2.10 Logging function – LOG + +Alarm history management is concerned with the recording of alarms. Historical data shall be stored in registers in the NE. Each register contains all the parameters of an alarm message. + +Registers shall be readable on-demand or periodically. The OS can define the operating mode of the registers as wrapping, or stop, when full. The OS may also flush the registers or stop recording at any time. + +NOTE – Wrapping is the deletion of the earliest record to allow a new record when a register is full. Flushing is the removal of all records in the register. See [ITU-T X.735] for additional details. + +**Symbol:** + +![Symbol diagram for the Logging function (LOG). An input signal labeled 'rZZZ-value' and 'rZZZ-severity' enters a box labeled 'LOG' from the left. A 'Query' signal enters the box from the right. A 'Report' signal exits the box to the right. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-12'.](2dfd7b53bd3c518fc1f68921ed2bf441_img.jpg) + +Symbol diagram for the Logging function (LOG). An input signal labeled 'rZZZ-value' and 'rZZZ-severity' enters a box labeled 'LOG' from the left. A 'Query' signal enters the box from the right. A 'Report' signal exits the box to the right. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-12'. + +**Figure 7-12 – Logging function** + +**Interfaces:** + +**Table 7-12 – Logging input and output signals** + +| Input(s) | Output(s) | +|--------------------------------------|-----------| +| rZZZ-value
rZZZ-severity
Query | Report | + +**Processes:** + +The log function provides a filter according to the "discriminator construct" defined in [ITU-T X.735]. The alarm records shall be stored. Upon query, the stored alarm information shall be reported. + +#### 7.2.2.11 TMN alarm event notifications function – TAN + +Symbol: + +![Symbol diagram for the TMN alarm event notifications function (TAN). The diagram shows a rectangular block labeled 'TAN'. On the left, an input arrow points to the block, labeled with 'rZZZ-value' and 'rZZZ-severity'. Below the block, an input arrow points up to it, labeled 'NE-RTC'. On the right, two output arrows point away from the block, labeled 'TMN alarm event notifications' and 'Other notifications'. At the bottom right of the diagram, the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-13' is present.](1ab49904e6a60be337d5b75cb7cc8ab7_img.jpg) + +Symbol diagram for the TMN alarm event notifications function (TAN). The diagram shows a rectangular block labeled 'TAN'. On the left, an input arrow points to the block, labeled with 'rZZZ-value' and 'rZZZ-severity'. Below the block, an input arrow points up to it, labeled 'NE-RTC'. On the right, two output arrows point away from the block, labeled 'TMN alarm event notifications' and 'Other notifications'. At the bottom right of the diagram, the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-13' is present. + +Figure 7-13 – TMN alarm event notifications function + +Interfaces: + +Table 7-13 – TMN alarm event notifications input and output signals + +| Input(s) | Output(s) | +|---------------------------------------|------------------------------------------------------| +| rZZZ-value
rZZZ-severity
NE-RTC | TMN alarm event notifications
Other notifications | + +Processes: + +The TMN alarm event notifications function is responsible for filtering and forwarding event notifications (see "event forwarding discriminator" in [ITU-T X.734] and [ITU-T X.754]). + +The TAN function uses the NE-RTC when time-stamping the time of the event report. + +#### 7.2.2.12 Current problem list function – CPL + +Symbol: + +![Symbol diagram for the Current problem list function (CPL). The diagram shows a rectangular block labeled 'CPL'. On the left, an input arrow points to the block, labeled with 'fZZZ-value', 'fZZZ-severity', and 'fZZZ-arc'. On the right, an output arrow points away from the block, labeled 'Current problem list'. At the bottom right of the diagram, the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-14' is present.](19d7a7ce68d3e9036613910b761c4b24_img.jpg) + +Symbol diagram for the Current problem list function (CPL). The diagram shows a rectangular block labeled 'CPL'. On the left, an input arrow points to the block, labeled with 'fZZZ-value', 'fZZZ-severity', and 'fZZZ-arc'. On the right, an output arrow points away from the block, labeled 'Current problem list'. At the bottom right of the diagram, the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-14' is present. + +Figure 7-14 – Current problem list function + +Interfaces: + +Table 7-14 – Current problem list input and output signals + +| Input(s) | Output(s) | +|-----------------------------------------|----------------------| +| fZZZ-value
fZZZ-severity
fZZZ-arc | Current problem list | + +Processes: + +The current problem list function is responsible for updating the current problem list in each managed entity. The current problem list shall contain the failure and alarm status of all current declared failures regardless of whether they will not be sent as a notification. + +#### 7.2.2.13 Alarm status function – AST + +Symbol: + +![Symbol diagram for the Alarm status function (AST). A rectangular box labeled 'AST' has three input arrows on the left labeled 'fZZZ-value', 'fZZZ-severity', and 'fZZZ-arc'. It has one output arrow on the right labeled 'Alarm status'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-15'.](834fb96b114b8fdc001625e1ae28e8b1_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F7-15 + +Symbol diagram for the Alarm status function (AST). A rectangular box labeled 'AST' has three input arrows on the left labeled 'fZZZ-value', 'fZZZ-severity', and 'fZZZ-arc'. It has one output arrow on the right labeled 'Alarm status'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-15'. + +Figure 7-15 – Alarm status function + +Interfaces: + +Table 7-15 – Alarm status input and output signals + +| Input(s) | Output(s) | +|-----------------------------------------|--------------| +| fZZZ-value
fZZZ-severity
fZZZ-arc | Alarm status | + +Processes: + +The alarm status function is responsible for updating the alarm status of each managed entity. The alarm status indicates the occurrence of an abnormal condition relating to a managed entity. It may also function as a summary indicator of alarm conditions associated with a specific resource. It is used to indicate the existence of an alarm condition, a pending alarm condition such as threshold situations, or (when used as a summary indicator) the highest severity of active alarm conditions. When used as a summary indicator, the order of severity (from highest to lowest) is critical, major, minor, warning, not alarmed (refer to Table 7-2). + +#### 7.2.2.14 Operational state function – OPS + +Symbol: + +![Symbol diagram for the Operational state function (OPS). A rectangular box labeled 'OPS' has one input arrow on the left labeled 'fZZZ-value'. It has one output arrow on the right labeled 'Operational state'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)_F7-16'.](ccdeaf31dbe65613f2f87a7b2b06e391_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F7-16 + +Symbol diagram for the Operational state function (OPS). A rectangular box labeled 'OPS' has one input arrow on the left labeled 'fZZZ-value'. It has one output arrow on the right labeled 'Operational state'. Below the box is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F7-16'. + +Figure 7-16 – Operational state function + +Interfaces: + +Table 7-16 – Operational state input and output signals + +| Input(s) | Output(s) | +|------------|-------------------| +| fZZZ-value | Operational state | + +Processes: + +The operational state function is responsible for updating the operational state in each managed entity, and optionally feeding into the operational state function for dependent managed entities. + +The operational state defines whether the managed entity is able to partially, or fully, perform the service (enabled), or is totally inoperable (disabled). This is according to [ITU-T X.731]. + +# 8 Configuration management + +Configuration management provides functions to exercise control over, identify, collect data from and provide data to NEs. Configuration management supports network planning and engineering, installation, service planning and negotiation, provisioning, and status and control. + +Figure 8-1 outlines the configuration management functions inside the EMF. In general, all these functions accept provisioning data from the MAF, perform a data check and return the check status to the MAF. Depending on the check status, it is decided to update the MIB related to the new provisioning data. + +Some functions accept control information from the MAF, are able to provide reporting data to the MAF, and have access to the atomic functions by means of MI signals. + +It is assumed that the configuration management functions alarm severity, report options, and PM thresholds only perform a data check. Subsequent processing is done in fault management and performance monitoring. + +Furthermore, Figure 8-1 is not intended to be a coherent functional model. It just lists the configuration management functions, and the interfaces with the atomic functions, the message communication function and the date and time function. + +![Diagram of Configuration management inside the EMF showing internal functions and their interfaces with Atomic functions, MAF, and Date and time.](a5184899f915014fa38608754efcc9c7_img.jpg) + +The diagram illustrates the internal structure of the Configuration management (CM) block within the Equipment Management Function (EMF). The CM block is a large green rectangle containing a grid of smaller white boxes, each representing a specific function. The functions are organized as follows: + +- Row 1:** Hardware, Software, Protection Switching, Trail termination +- Row 2:** Adaptation, Connection, EXC/DEG thresholds, ZZZ\_Reported +- Row 3:** Alarm severity, Alarm reporting control, PM thresholds, Tandem connection monitoring +- Row 4:** Date and time, Fault event filtering + +External interfaces are shown on the left and right sides of the CM block: + +- Left Interface:** A vertical box labeled "Atomic functions" containing a series of red diamond shapes. Two arrows connect this box to the CM block: one labeled "provisioning, control" pointing into the CM, and another labeled "status, reporting" pointing out of the CM. +- Right Interface:** A vertical box labeled "Management application function (MAF)". Two arrows connect the CM block to this box: one labeled "provisioning, control" pointing out of the CM, and another labeled "status, reporting" pointing into the MAF. + +Reference code: G.7710-Y.1701(20)-Amd.1(22)\_F8-1 + +Diagram of Configuration management inside the EMF showing internal functions and their interfaces with Atomic functions, MAF, and Date and time. + +**Figure 8-1 – Configuration management inside the EMF** + +Within the scope of this Recommendation, i.e., the equipment management functions inside the NE, the applications are limited to provisioning and control and status reporting. The applications descriptions include the provisioning of the NE's hardware and software. It includes the provisioning of atomic functions by means of MI signals (as specified by the technology-specific Recommendations). It includes the provisioning of some of the FCAPS functions, like performance monitoring thresholds and protection switching schemes. This Recommendation does not include the MIB-related applications (e.g., upload and download). + +## 8.1 Hardware + +### 8.1.1 Provisioning + +An NE should provide various functions that allow provisioning of the hardware such as slot provisioning, circuit pack assignment and port provisioning. + +### 8.1.2 Inventory reporting + +An inventory of the provisioned, or present hardware, must be reported on request of an external command. + +## 8.2 Software + +### 8.2.1 Provisioning + +An NE may accept new software versions to be downloaded. The loading includes initialization and testing that the load is successful and back-out of the software if the load is not successfully completed. The NE will support in-service software upgrades, at minimum, between two consecutive versions of a software release. Note that during software switchover, some management services may be impacted. For example, creation of new services during this period may not be allowed. + +In support of software download, NEs shall additionally support the software management requirements specified in clause 6 of [ITU-T X.744]. + +### 8.2.2 Inventory reporting + +An inventory of the present software release is reported on request of an external command. + +## 8.3 Protection switching + +The general scheme of protection switching is defined as the substitution of a standby or back-up facility for a designated facility. The scheme includes functions which allow the user to control the traffic on the protection line. These are: + +- operate/release manual protection switching; +- operate/release force protection switching; +- operate/release lockout; +- request/set automatic protection switching (APS) parameters. + +### 8.3.1 Provisioning + +NEs may support one or more types of protection schemes: + +- Trail protection (e.g., linear OMSP, linear MSP, MS SPRing, VC); +- Subnetwork connection protection (e.g., VC, OCH, linear ETH). + +Each scheme can be characterized by the set (or a subset) of the following parameters: + +- topology (linear (see [ITU-T G.808.1]), ring (see [ITU-T G.808.2])); +- protection architecture (1+1, 1:n); +- switching type (unidirectional/single ended, bidirectional/dual ended); +- operation type (non-revertive, revertive); +- automatic protection switching (APS) channel (provisioning, usage, coding); +- protection switch requests; +- protection switch performance; +- protection switch state machine. + +The protection switching scheme of an NE can be set up autonomously by the NE itself according to its make-up and mode of operation, or it may be done by means of external provisioning. + +### 8.3.2 Reporting + +The protection switching block in Figure 8-1 reports the current status of protection switching (e.g., status of protocol state machine, condition of blocking port, etc.). Note that this reporting information is used to monitor the protocol status from outside the NEs. To realize this reporting, an atomic function shall report protocol-related state information to the EMF by means of MI signals (as defined in technology-specific recommendations). The protection switching state handling function is responsible for receiving and forwarding protocol-related state information to the MAF. + +#### 8.3.2.1 Protection switching (PS) state handling function + +Symbol: + +![Diagram of the PS state handling function symbol. It shows two rectangular boxes: 'State change detection' and 'Current state'. An input signal 'PS state' enters from the left and splits into both boxes. From 'State change detection', an output signal 'PS event notification' exits to the right. From 'Current state', two output signals exit to the right: 'PS state query' (top) and 'PS state report' (bottom). Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)_F8-2'.](e22af684d8e56d4c61e61bb5ddac1087_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F8-2 + +Diagram of the PS state handling function symbol. It shows two rectangular boxes: 'State change detection' and 'Current state'. An input signal 'PS state' enters from the left and splits into both boxes. From 'State change detection', an output signal 'PS event notification' exits to the right. From 'Current state', two output signals exit to the right: 'PS state query' (top) and 'PS state report' (bottom). Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F8-2'. + +Figure 8-2 – PS state handling function + +Interfaces: + +Table 8-1 – PS state handling input and output signals + +| Input(s) | Output(s) | +|---------------------------|-----------------------| +| PS State (via MI signals) | PS Event Notification | +| PS State Query | PS State Report | + +Processes: + +The PS state handling function is responsible for receiving and forwarding protocol-related state information to the MAF. The state change detection process detects a change of protocol state and autonomously notifies it as an event signal (PS Event Notification) when an input signal (PS State) changes. The current state process latches the latest protocol state and reports the information (PS State Report) when the MAF requests it on-demand basis (via PS Event Query). + +## 8.4 Trail termination + +The purpose of the trail termination is to generate, add and monitor information concerning the integrity and supervision of adapted information. This includes: + +- connectivity supervision; +- continuity supervision; +- signal quality supervision; +- processing of maintenance information (forward/backward indications). + +### 8.4.1 Provisioning + +#### 8.4.1.1 Trail trace identifier + +The TTI is used to ensure proper connection between network elements and to generate a trail trace identifier mismatch alarm if the accepted value is different from the expected value. The TTI is useful in meshed network topology with cross-connections that have several input and output ports. TTIs are also a means for the OS to deduce the network topology. Specifically, the OS gets the list of source and sink TTIs of all network elements and can automatically deduce the trails at a specific layer by a comparison of the expected TTIs of the sink objects and the TTIs sent from the source objects. + +The trail trace identifier (TTI) process needs to be provisioned with the TTI to transmit, with the expected TTI, and with a qualifier to determine the trace identifier mismatch detection. The provisioning can be under control of the management plane, the control plane, or a combination of both. + +The functions that allow a user to provision the operation of a trace identifier process are: + +- provisioning of source TTI; + +- provisioning of the expected TTI; +- enable/disable detection of trace identifier mismatch (TIM); +- enable/disable TIM consequent action. + +The source TTI and the expected TTI are communicated to the trail termination functions from the EMF via management signals at the management points. + +The detection mode for TIM is communicated to an atomic function from the EMF via the management signals at the management points. + +An atomic function shall report, at the request of the EMF, the value of the received and accepted TTI via the management signals at the management points. The TIM consequent action enabling/disabling control signal is communicated to an atomic function from the EMF via management signals at the management points. + +#### 8.4.1.2 Maintenance entity group identifiers + +For packet transport networks, three types of maintenance entity identifiers are defined for connectivity checking: + +- MEGID "maintenance entity group (MEG) identifier"; +- MEPID "MEG end point identifier"; +- MIPID "MEG intermediate point identifier". + +These identifiers are used to ensure proper connectivity between the endpoints of a maintenance entity group and to generate a: + +- mismerge; +- loss of continuity; or +- unexpected MEP. + +Alarm if the received value is different from the expected value. The identifiers are useful in meshed network topology with matrix connection and FDFrs that have several input and output ports to check continuity and connectivity between all ports. + +The connectivity check process needs to be provisioned with the identifiers to transmit, with the expected identifiers, and enable/disable the connectivity check process. The provisioning can be under the control of the management plane, the control plane, or a combination of both. + +The functions that allow a user to provision the operation of a connectivity check process are: + +- provisioning of the MEGID and the local MEPID; +- provisioning of the remote MEPIDs; +- enable/disable connectivity checking. + +The identifiers are communicated to the trail/flow termination functions from the EMF via management signals at the management points. + +An atomic function shall report, at the request of the EMF, the content of the connectivity check fields via the management signals at the management points. + +### 8.4.2 Reporting + +#### 8.4.2.1 Trail trace identifier + +The TTI process supports the reporting of the accepted TTI. + +#### 8.4.2.2 Maintenance identifiers + +The connectivity check process supports the reporting of the received connectivity check frame/packet. + +## 8.5 Adaptation + +### 8.5.1 Provisioning + +Access points which have multiple adaptation functions connected to them, allowing different client signals to be transported via the server signal, need a selection of the active client. The selection of the active client can be provisioned by means of the activation of the related adaptation function. For cases where an access point has a single adaptation function connected, and supports a single client signal only, the selection is fixed. Table 8-2 gives an overview of the provisioning items and the MI signals, including range and defaults, used to configure the appropriate atomic functions. + +**Table 8-2 – Payload structures provisioning** + +| Provisioning | Management information (MI) | | | +|-------------------------------------|-----------------------------|-------------|---------| +| | MI signal | Value range | Default | +| – activation of adaptation function | MI_Active | true, false | false | + +### 8.5.2 Reporting + +An atomic function will report on request the value of the received and accepted payload type signal. See clause 7.2.1.1.1, payload type supervision, for details. Table 8-3 gives an overview of the reporting items and the MI signals, including range and defaults, received from the appropriate atomic functions. + +**Table 8-3 – Payload structures reporting** + +| Reporting | Management information (MI) | | | +|-------------------------------------------|-----------------------------|-----------------------|---------| +| | MI signal | Value range | Default | +| – received and accepted path signal label | MI_AcSL | application-dependent | N/A | + +## 8.6 Connection + +### 8.6.1 Provisioning + +A connection function is surrounded by connection points (CPs)/flow points (FPs) and termination connection points (TCPs)/termination flow points (TFPs). Each TCP/TFP is identified via the API associated with its trail termination function, and each CP/FP is identified via the API associated with its adaptation function, extended with a (if applicable) tributary signal number (see Figures 8-3, 8-4 and 8-5). + +Reconfigurable network elements provide connection capabilities at specific layers. Cross-connections can be configured between all attached ports. + +The following provisioning functions are identified: + +- 1) Create a + - point-to-point (unidirectional or bidirectional); + - point-to-multipoint (unidirectional); + - multipoint-to-multipoint (bidirectional); + - rooted multipoint (bidirectional); + - matrix connection and FDFr. + +- 2) Remove a +- point-to-point (unidirectional or bidirectional); + - point-to-multipoint (unidirectional); + - multipoint-to-multipoint (bidirectional); + - rooted multipoint (bidirectional); + - matrix connection or FDFr. + +For the case of a trail protection, the access points (APs) are named as follows: AP of working #i and AP of normal #i have the same AP identifier, AP of protection has a separate AP identifier, AP of extra traffic has the same AP identifier as the AP of protection. This maintains the CPIds when the interface changes from unprotected to protected and vice versa. + +A matrix connection is therefore characterized by a set of CP/FP or TCP/TFP identifiers connected to each other. Table 8-4 gives an overview of the provisioning items and the MI signals, including range and defaults, used to configure the appropriate atomic functions. + +**Table 8-4 – Matrix connections provisioning** + +| Provisioning | Management information (MI) | | | +|---------------------|-----------------------------|---------------------------------|------------| +| | MI signal | Value range | Default | +| – matrix connection | MI_ConnectionPortIds | set of (T)CP/FP Ids | no default | +| | MI_ConnectionType | unprotected, 1+1 protected, ... | no default | +| | MI_Directionality | unidirectional, bidirectional | no default | + +![Diagram illustrating the CP/FP and TCP/TFP identification scheme. It shows a hierarchy of nodes: CP (Circuit Point), AP (Access Point), and TCP (Tunnel Control Point). The top section shows two CPs connected to an AP, with labels 'CP Id = AP Id/TSN' and 'AP Id = API'. Below this, a TCP is connected to the AP, with a label 'TCP Id = AP Id'. The bottom section shows another CP connected to an AP, which is connected to a TCP, with labels 'CP Id = AP Id' and 'TCP Id = AP Id'. The diagram uses ovals to group related components and arrows to show connections and identification relationships.](1ce027dfd26183da52137cf990213724_img.jpg) + +Diagram illustrating the CP/FP and TCP/TFP identification scheme. It shows a hierarchy of nodes: CP (Circuit Point), AP (Access Point), and TCP (Tunnel Control Point). The top section shows two CPs connected to an AP, with labels 'CP Id = AP Id/TSN' and 'AP Id = API'. Below this, a TCP is connected to the AP, with a label 'TCP Id = AP Id'. The bottom section shows another CP connected to an AP, which is connected to a TCP, with labels 'CP Id = AP Id' and 'TCP Id = AP Id'. The diagram uses ovals to group related components and arrows to show connections and identification relationships. + +NOTE – While this figure is drawn in the context of circuit-based terminology, the same figure is valid for packet-based terminology by replacing CP by FP and TCP by TFP. + +G.7710-Y.1701(20)-Amd.1(22)\_F8-3 + +**Figure 8-3 – CP/FP and TCP/TFP identification scheme** + +![Figure 8-4: CP/FP and TCP/TFP identification scheme for the case of 1+1 trail protection. The diagram shows a stack of layers: CP (Circuit Packets) at the top, followed by AP (ATM Packets), then TCP (TDM Packets). Below TCP is a 'Normal' section with 'Working' and 'Protection' sublayers. The Working sublayer has a CP, AP, and TCP stack. The Protection sublayer has a CP, AP, and TCP stack. Labels indicate: CP Id = AP Id, AP Id = API-1, TCP Id = AP Id, and Protection sublayer. A note at the bottom right states: G.7710-Y.1701(20)-Amd.1(22)_F8-4.](5ee1bbbf85b473f78af9ec8368a4159a_img.jpg) + +Figure 8-4: CP/FP and TCP/TFP identification scheme for the case of 1+1 trail protection. The diagram shows a stack of layers: CP (Circuit Packets) at the top, followed by AP (ATM Packets), then TCP (TDM Packets). Below TCP is a 'Normal' section with 'Working' and 'Protection' sublayers. The Working sublayer has a CP, AP, and TCP stack. The Protection sublayer has a CP, AP, and TCP stack. Labels indicate: CP Id = AP Id, AP Id = API-1, TCP Id = AP Id, and Protection sublayer. A note at the bottom right states: G.7710-Y.1701(20)-Amd.1(22)\_F8-4. + +NOTE – While this figure is drawn in the context of circuit-based terminology the same figure is valid for packet-based terminology by replacing CP by FP and TCP by TFP. + +**Figure 8-4 – CP/FP and TCP/TFP identification scheme for the case of 1+1 trail protection** + +![Figure 8-5: CP/FP and TCP/TFP identification scheme for the case of 1:n trail protection. The diagram shows three parallel stacks of layers: Normal 1 (Working 1), Normal 2 (Working 2), and Extra traffic protection. Each stack has CP, AP, and TCP layers. Labels indicate: AP Id = API-1, AP Id = API-2, AP Id = API-0, TCP Id = AP Id, CP Id = AP Id, and Protection sublayer. A note at the bottom right states: G.7710-Y.1701(20)-Amd.1(22)_F8-5.](3442f31a562d1ef45bfa18b18a6a1ddc_img.jpg) + +Figure 8-5: CP/FP and TCP/TFP identification scheme for the case of 1:n trail protection. The diagram shows three parallel stacks of layers: Normal 1 (Working 1), Normal 2 (Working 2), and Extra traffic protection. Each stack has CP, AP, and TCP layers. Labels indicate: AP Id = API-1, AP Id = API-2, AP Id = API-0, TCP Id = AP Id, CP Id = AP Id, and Protection sublayer. A note at the bottom right states: G.7710-Y.1701(20)-Amd.1(22)\_F8-5. + +NOTE – While this figure is drawn in the context of circuit-based terminology the same figure is valid for packet-based terminology by replacing CP by FP and TCP by TFP. + +**Figure 8-5 – CP/FP and TCP/TFP identification scheme for the case of 1:n trail protection** + +### 8.6.2 Reporting + +The following reporting functions are identified: + +- 1) *Get connectivity capabilities:* + +Because reconfigurable network elements may have static cross-connection restrictions, the OS should be aware of these restrictions. + +This function gives an overview of the fabric's static capability to connect termination points. This is done by identifying one or more sets of termination points which can be interconnected. + +Restrictions of connectivity may be caused by principal design of the switch matrix or by the fact that not all sink termination points are fully reachable from all source termination points. + +This function should not take limited processing capacity, usage, or current problems into account. These additional restrictions have to be considered dynamically by the OS. + +#### 2) *Report connectivity changes of a cross-connect:* + +The NE has to send a report when the connectivity of the fabric changes. Note that after receiving a report about connectivity changes, the OS may again get all connectivity sets to update its connectivity topology. + +#### 3) Report the creation of a point-to-point cross-connection. + +#### 4) Report the deletion of a point-to-point cross-connection. + +#### 5) Report the suspend/resume of traffic on a point-to-point cross-connection. + +#### 6) *Get all point-to-point cross-connections:* + +This action returns the list of all point-to-point cross-connections created. + +## 8.7 Threshold of error distribution defects + +The EXE and DEG threshold MI signals are sent to the AF from the EMF to set thresholds of the EXE and DEG defects. Defect of excessive error (EXE) or degraded signal (DEG) depend on the distribution of errors in the network. Excessive error defect (dEXE) and degraded signal defect (dDEG) could be supported by Poisson mode distribution and only degraded signal defect (dDEG) could be supported by burst distribution. The application of Forward Error Correction (FEC) and Decision Feedback Equalizer (DFE) will make the error distribution as burst mode. The applicability of each mode to specific technology is specified in technology specific Recommendations such as [b-ITU-T G.874], [b-ITU-T G.8052], etc. + +### 8.7.1 Provisioning + +The threshold and monitor period of the burst-based degraded defect process requires provisioning. Table 8-5 gives an overview of the provisioning items and the MI signals, including range and defaults, used to configure the appropriate atomic functions. + +**Table 8-5 – Error defect threshold provisioning** + +| Provisioning | Management information (MI) | | | +|-----------------------------------------------------|-----------------------------|-----------------------------------------------|--------------------------------------------| +| | MI signal | Value range | Default | +| – Poisson-based excessive defect threshold | MI_EXC_X | $10^{-3}, 10^{-4}, 10^{-5}$ | $10^{-3}$ | +| – Poisson-based degraded defect threshold | MI_DEG_X | $10^{-5}, 10^{-6}, 10^{-7}, 10^{-8}, 10^{-9}$ | $10^{-6}$ | +| – Burst-based degraded defect interval threshold | MI_DEGTHR | 0..N EBs or 0..100% | Near-end SES threshold (see clause 10.2.1) | +| – Burst-based degraded defect monitor period | MI_DEGM | 2..10 | 7 | +| – Frame-based minimum transmitted frames per second | MI_LM_TFMIN | $0..(2^{32} - 1)$ | N/A | + +**Table 8-5 – Error defect threshold provisioning** + +| Provisioning | Management information (MI) | | | +|------------------------------------------------------------------------------------------------|------------------------------------|--------------------|-----------------------------------------------| +| | MI signal | Value range | Default | +| – Frame-based threshold of percentage of loss frames for declaring bad-second | MI_LM_DEGTHR | 0..100% | Near-end SES threshold
(see clause 10.2.1) | +| – Frame-based threshold of consecutive bad/good seconds for declaring/clearing Degraded defect | MI_LM_DEGM,
MI_LM_M | 2..10 | 7 | + +The provisioning of these signals is individual per trail in the NE. + +## **8.8 Defect reporting control** + +### **8.8.1 Provisioning** + +The reporting of certain "secondary defects" is optional. Secondary defects are the result of a consequent action on a "primary defect" in another network element. The ZZZ\_reported MI signal sent to the AF from the EMF is used to control the defect reporting, and is defined in the technology-specific Recommendations. The control of the reporting is by the parameter MI\_ZZZ\_Reported defined in the technology-specific Recommendations. + +The granularity of these signals is outside the scope of this Recommendation. Examples are: + +- global per network element +- global per network layer in the network element +- global per server/aggregate signal in the network element +- individual per trail/signal in the network element. + +The two extremes are "provisioning per individual signal" and "provisioning per network element". The first example offers full flexibility with relative high complexity in equipment and in management. The second example offers low complexity in equipment and in management with very limited flexibility. + +Equipment will support one or more of these options, depending on the intended application of the equipment in the network. + +## **8.9 Alarm severity assignment** + +### **8.9.1 Provisioning** + +The severity assignment function (SEV, see clause 7.2.2.2) inside fault management requires the provisioning of an alarm severity assignment for the managed entities. Table 8-6 gives an overview of the provisioning items, including range and defaults. Note that the provisioning is not related to an atomic function. + +**Table 8-6 – Alarm severity provisioning** + +| Provisioning | Value range | Default | +|------------------------------------------------|----------------------------------------------|---------------------------------------------------------| +| – alarm severity assignment per managed entity | Critical, major, minor, warning, not alarmed | For primary failures:
(event and equipment-specific) | +| | | For secondary failures:
Not Alarmed | + +## 8.10 Alarm reporting control (ARC) + +### 8.10.1 Provisioning + +The ARC function (see clause 7.2.2.3) inside fault management requires the provisioning of the ARC mode per instance. Table 8-7 gives an overview of the provisioning items, including range and defaults. Note that the provisioning is not related to an atomic function. + +**Table 8-7 – ARC provisioning** + +| Provisioning | Value range | Default | +|-------------------------------------------|--------------------------------------|---------------------| +| – ARC state | ALM, NALM, NALM-TI, NALM-QI | Technology-specific | +| – ARC list of probable causes to suppress | Application-dependent | N/A | +| – TI-time | 0.99 hours with 1-minute granularity | see [ITU-T M.3100] | +| – CD-time | 0.99 hours with 1-minute granularity | see [ITU-T M.3100] | + +## 8.11 PM thresholds + +Most services are offered to customers with a predefined level of availability (e.g., standard service, premium service, etc.). For each service, a set of PM threshold values will be defined to supervise the fulfilment of the availability. This set of PM thresholds is common for all termination points that carry traffic of the same service. Changes in the quality of the service offered to the customer lead to a change in the associated threshold value set in every termination point carrying this kind of service. + +Therefore, PM thresholds are set by assigning a threshold value profile to the termination points to be supervised. This functionality provides the ability to change PM thresholds for a group of termination points at the same time by changing only the values in the assigned profile. Default profiles which are assigned to every newly created termination point are configurable during creation time. + +## 8.12 Tandem connection monitoring (TCM) activation + +### 8.12.1 Provisioning + +If a TCM function needs to be activated at a CTP, which already has activated TCM functions, the traffic may not be affected. Figure 8-6 outlines the possibilities. The upper part shows the initial situation at the CTP with TCM functions A and B activated. When the operator has to provision a new TCM, he/she must know the required position of the new TCM in relation to the existing TCMs A and B. In general, three insertion points are possible: + +- 1) left to the most left; +- 2) between two others; and + +3) right to the most right. + +This is illustrated in the lower part of Figure 8-6. + +![Figure 8-6 – TCM activation provisioning. The diagram shows three scenarios for inserting a new TCM function relative to existing TCM functions A and B. At the top, a sequence of TCM functions A and B is shown with three insertion points marked by arrows and numbers 1, 2, and 3. Point 1 is to the left of A, point 2 is between A and B, and point 3 is to the right of B. Below this, three sub-diagrams illustrate the resulting configurations: 1) New TCM left to A, showing a new TCM function to the left of A and B; 2) New TCM between A and B, showing the new TCM function inserted between A and B; 3) New TCM right to B, showing the new TCM function to the right of A and B. A reference code G.7710-Y.1701(20)-Amd.1(22)_F8-6 is provided at the bottom right.](640d28a694bbdbaf9b11a3bfdcc800fc_img.jpg) + +Insertion points for new TCM + +1) New TCM left to A      2) New TCM between A and B      3) New TCM right to B + +G.7710-Y.1701(20)-Amd.1(22)\_F8-6 + +Figure 8-6 – TCM activation provisioning. The diagram shows three scenarios for inserting a new TCM function relative to existing TCM functions A and B. At the top, a sequence of TCM functions A and B is shown with three insertion points marked by arrows and numbers 1, 2, and 3. Point 1 is to the left of A, point 2 is between A and B, and point 3 is to the right of B. Below this, three sub-diagrams illustrate the resulting configurations: 1) New TCM left to A, showing a new TCM function to the left of A and B; 2) New TCM between A and B, showing the new TCM function inserted between A and B; 3) New TCM right to B, showing the new TCM function to the right of A and B. A reference code G.7710-Y.1701(20)-Amd.1(22)\_F8-6 is provided at the bottom right. + +**Figure 8-6 – TCM activation provisioning** + +From the NE point of view, two behaviours are possible. + +- The NE provides flexible allocation of new TCM functions. In this case, the operator only has to specify the location of the new TCM function, in relation to the existing ones, at the same CTP. +- The NE provides no flexibility. The order of the TCM functions at the CTP is fixed. In this case, the operator may have to rearrange existing functions in order to free the location for the new function. This rearrangement should be hitless for the traffic. However, inconsistencies in the supervision process might not be avoided. + +## 8.13 Date and time + +The date and time functions comprise the local real-time clock (RTC) function and the performance monitoring clock (PMC) function. The message communication function (MCF) is able to set the local real-time clock function. The date and time is incremented by the local real-time clock function. The FCAPS functions that need date and time information, e.g., to time stamp event reports, get this information from the date and time functions. + +The requirements for the local real-time clock function and the performance monitoring clock are specified in clause 8.13.2. These requirements are based on the date and time applications, described in clause 8.13.1. + +The following abbreviations are used for the times in this clause: + +- C The adjustment in time to compensate for delivery delay. +- S The difference in time between the arrival of the time signal at the edge of the NE and the time indicated on the local real-time clock, immediately after a reset local clock request has been completed. +- X The delivery delay of the time signal from the external time reference to the edge of the NE. +- Y The drift of the local real time clock within a 24-hour interval of the external time reference. +- Z The difference between the time that a prescribed event is detected by the NE and the time that the NE assigns to this event. + +### 8.13.1 Date and time applications + +The three identified applications related to date and time are the capabilities to time-stamp event reports (e.g., alarms), to monitor clock signals and to schedule activities. + +#### 8.13.1.1 Time-stamping + +A number of functions/processes and reports require a relatively precise and consistent current time. The NE local real-time clock function provides this time information. [ITU-T M.2140] suggests that faults and performance degradations should be correlated to the root cause problem. To meet this need, time-stamping of the event data is essential, see Figure 8-7. + +![Figure 8-7: Illustration of time-stamping. A dashed box labeled 'Network element function' contains a 'Local real-time clock function' (clock icon), an 'Event detection' point, and a 'Time-stamping' block. 'Event detection' points to 'Time-stamping'. 'Local real-time clock function' has a bidirectional arrow with 'Time-stamping'. 'Time-stamping' outputs to 'Time-stamp value acquired'. A double-headed arrow between 'Event detection' and 'Time-stamp value acquired' is labeled '± Z seconds'.](fe7304192caf64cda93b580c5e7e5c06_img.jpg) + +``` + +graph LR + subgraph "Network element function" + Clock[Local real-time clock function] <--> TS[Time-stamping] + ED[Event detection] --> TS + end + TS --> VA[Time-stamp value acquired] + ED -. "± Z seconds" .-> VA + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F8-7 + +Figure 8-7: Illustration of time-stamping. A dashed box labeled 'Network element function' contains a 'Local real-time clock function' (clock icon), an 'Event detection' point, and a 'Time-stamping' block. 'Event detection' points to 'Time-stamping'. 'Local real-time clock function' has a bidirectional arrow with 'Time-stamping'. 'Time-stamping' outputs to 'Time-stamp value acquired'. A double-headed arrow between 'Event detection' and 'Time-stamp value acquired' is labeled '± Z seconds'. + +**Figure 8-7 – Illustration of time-stamping** + +Events, performance reports and registers, containing event counts or gauge values that require time-stamping shall be time-stamped with a resolution of one second relative to the NE local real-time clock function. This resolution exceeds some of the specifications in [ITU-T M.2120]. The date/time-stamps shall be according to the coordinated universal time (UTC), containing day, month, year, hour, minute and second. The display of this date/time-stamps may be done in local time by applying the appropriate offset to the UTC time. + +Events and reports shall be time-stamped as follows: + +- 1) The time-stamp for fault events (declaration/clearing) shall indicate the start of the fault cause prior to failure integration time. +- 2) The performance measurement intervals shall contain the time-stamp associated with the measurement interval. This is, for example, consistent with the periodEndTime attribute in the historyData object class defined in [ITU-T Q.822]. +- 3) The time-stamp for threshold report (TR) declaration and reset threshold report (RTR) declaration shall indicate the time of the event according to the performance monitoring clock (see clause 8.13.1.2). This is consistent with [ITU-T M.2120]. +- 4) All other requests and reports shall contain the time-stamp associated with the actuation. + +The start of counting intervals should be accurate to within $\pm 10$ s with respect to the NE local real-time clock function. For example, a 15-minute register may begin its 2:00 count between 1:59:50 and 2:00:10. + +The symbol Z in Figure 8-7 represents the difference between the time that a prescribed event is detected by the NE and the time that the NE assigns to this event. It is an objective that the value of Z is less than, or equal to, one second. Specifications of Z are defined in the technology-specific ITU-T Recommendations. + +#### 8.13.1.2 Performance monitoring clock signals + +Performance monitoring functions ensure, among others, the summation of one second event counts during 15-minute and 24-hour intervals. The start of such an interval is equal to the end of the previous interval. There is a need to have a signal that indicates the start/end of a one second interval, a signal that indicates the start/end of a 15-minute interval and a signal that indicates the start/end of a 24-hour + +interval. The 15-minute intervals are aligned with the quarter of an hour, i.e., 00:00, 15:00, 30:00 and 45:00. The 24-hour interval starts by default at midnight (00:00:00) and no modification is recommended. In order to compare 24-hour intervals between network providers for connections, which span many time zones, it is necessary to have the ability to start the 24-hour intervals at midnight (00:00:00) UTC. + +#### 8.13.1.3 Activity scheduling + +A feature of NEs is the capability to schedule activities in advance. + +Examples of scheduled activities are performance monitoring reporting, integrity checking to be performed at regular intervals, and the provisioning of a cross-connection at a certain date and time. + +Figure 8-8 outlines the mechanism of activity scheduling. + +![Figure 8-8 – Activity scheduling diagram](cc6f9dbfc36aa5821d9749ca84861f93_img.jpg) + +The diagram illustrates the activity scheduling mechanism within a network element. A dashed box labeled 'Network element' contains three components: a 'Local real-time clock function' represented by a clock icon, a 'Scheduler' represented by a green rectangular block, and an 'Activity activation' output. Arrows show the flow: from the clock function to the scheduler, from an 'Activity list' input to the scheduler, and from the scheduler to the 'Activity activation' output. A reference label 'G.7710-Y.1701(20)-Amd.1(22)\_F8-8' is at the bottom right. + +Figure 8-8 – Activity scheduling diagram + +Figure 8-8 – Activity scheduling + +The activity list contains the activities along with their activation date and time. The latter may be indicated by a specific date and time (e.g., at 8.00 am Monday 15 October, 2007) or by a repetition (e.g., at 8.00 am Mondays). + +The scheduler continuously compares the date and time of the local real-time clock function with the activation date and time indicators in the activity list. When there is a match, the related activity is activated. + +### 8.13.2 Date and time functions + +There are three date and time functions defined. The local real-time clock (RTC) function is required for time-stamping and activity scheduling. The capabilities to align the local real-time clock function to an external clock reference, which are essential to give proper support for the date and time applications. The performance monitoring clock (PMC) function, in addition to RTC, is typical for digital counter measurements. + +#### 8.13.2.1 Local real-time clock function + +Symbol: + +![Figure 8-9 – Local real-time clock function diagram](15906392337ec83a921988b52f102a44_img.jpg) + +The diagram shows the symbol for the local real-time clock function. A rectangular block labeled 'Local real-time clock function' has an input arrow labeled 'SET-RTC' entering from the left and an output arrow labeled 'NE-RTC' exiting to the right. A dashed vertical line labeled 'TI\_CK' points to the bottom of the block. A reference label 'G.7710-Y.1701(20)-Amd.1(22)\_F8-9' is at the bottom. + +Figure 8-9 – Local real-time clock function diagram + +Figure 8-9 – Local real-time clock function + +##### **Interfaces:** + +**Table 8-8 – Local real-time clock function input and output signals** + +| Input(s) | Output(s) | +|------------------|-----------| +| SET-RTC
TI_CK | NE-RTC | + +##### **Processes:** + +The local real-time clock function is a logical entity within the NE providing date and time information to equipment management functions within the NE. The following requirements apply: + +- 1) The local real-time clock function may be a free running clock or may be locked to any available clock source (e.g., equipment clock TI\_CK). +- 2) The local real-time clock function shall have a resolution of 100 ms. +- 3) On receipt of a SET-RTC request, the local real-time clock function shall be set to the date and time specified by the SET-RTC request. +- 4) When the SET-RTC request is received, the difference in time between the management request at the input of the NE and the resultant NE-RTC shall be within S-C seconds. +- 5) The stability of the local RTC function shall be such that within 24 hours after a setting, the deviation shall not be greater than $\pm Y$ seconds. +- 6) The events and reports shall be time-stamped. The time-stamp should not result in a Z second difference from the local real-time clock function. +- 7) When the SET-RTC request causes an NE-RTC correction in magnitude of a difference greater or equal to 10 s, the NE shall emit a data change notification (e.g., attribute value change notification). + +#### **8.13.2.2 Local real-time clock alignment function with external time reference** + +A feature of NEs is the capability to align the local real-time clock function with an external time source. + +An example of a general external time reference source is the Greenwich Mean Time (GMT)-based clock. Such a clock signal can be distributed by a radio broadcast station (e.g., GPS) or through a data network (e.g., IP or CMISE). + +Figure 8-10 depicts the relationship between an NE's local real-time clock (RTC) function and an external time reference. + +The symbol X represents the delivery delay of the time signal from the external time reference to the edge of the network element. For a radio frequency-based time distribution, the value of X will be approximately zero. For an IP-based time distribution, not only X but also the variation of X could be several seconds. X accounts for time accuracy losses in the server time protocol function (e.g., signal encoding) and in the distribution network. The specifications for values of X are outside the scope of this Recommendation. + +![Figure 8-10: Local RTC function alignment with an external time reference. The diagram shows a sequence of components: External time reference (clock icon), Server time protocol function (yellow box), Time distribution network (yellow cloud), Network element (dashed box containing Client time protocol function (green box) and Local real-time clock function (clock icon)). Arrows indicate signal flow from left to right. Horizontal double-headed arrows above the components indicate 'External delivery delay X' (between external reference and network element), 'Internal delivery delay S' (within network element), and 'Delay compensation C' (between server function and client function). A horizontal double-headed arrow below the components indicates 'Deviation Y' (between client function and local clock). The text 'G.7710-Y.1701(20)-Amd.1(22)_F8-10' is at the bottom right.](c0b9e5fc63e19306394e0d4249da62cd_img.jpg) + +Figure 8-10: Local RTC function alignment with an external time reference. The diagram shows a sequence of components: External time reference (clock icon), Server time protocol function (yellow box), Time distribution network (yellow cloud), Network element (dashed box containing Client time protocol function (green box) and Local real-time clock function (clock icon)). Arrows indicate signal flow from left to right. Horizontal double-headed arrows above the components indicate 'External delivery delay X' (between external reference and network element), 'Internal delivery delay S' (within network element), and 'Delay compensation C' (between server function and client function). A horizontal double-headed arrow below the components indicates 'Deviation Y' (between client function and local clock). The text 'G.7710-Y.1701(20)-Amd.1(22)\_F8-10' is at the bottom right. + +**Figure 8-10 – Local RTC function alignment with an external time reference** + +The symbol $S$ represents the difference in time between the arrival of the time signal at the edge of the NE, and the time the corrective actions start on the local real-time clock function. $S$ accounts for time accuracy losses introduced in the client time protocol function (e.g., signal acceptance and decoding). It is an objective that the value of $S$ is less than or equal to 0.3 seconds. Specifications of $S$ are defined in the technology-specific ITU-T Recommendations. + +The symbol $Y$ represents the drift of the local real-time clock function within a 24-hour interval of the external time reference, under the condition that no time resets have occurred during the 24-hour interval. It is an objective that the value of $Y$ is such that $S + Y + Z$ is less than or equal to 1.5 seconds. Specifications of $Y$ are defined in the technology-specific ITU-T Recommendations. + +The symbol $C$ represents the adjustment in time to compensate for delivery delay. Various compensation protocols can be applied. A simple example is the compensation with a fixed value ( $C = \text{constant}$ ) or no compensation at all ( $C = 0$ ). The network time protocol, as specified in [b-IETF RFC 1305], is an advanced protocol able to compensate for the external and internal delivery delay ( $C = X + S$ ). Appendix II outlines a mechanism of a relatively simple protocol to set the local real-time clock function within a few seconds relative to the external time reference. The specification of protocols and values of $C$ are outside the scope of this Recommendation. + +With the previous definitions, the difference in time between the local real-time clock function and the external time reference, within 24 hours after a reset local clock, shall not exceed $X + S - C \pm Y$ . + +To compensate for the drift $Y$ , the local real-time clock function is to be realigned with the external time reference on a regular basis. This realignment period should be determined so that the correction is less than 10 s to prevent all active performance monitoring functions (PMFs) from declaring suspect intervals. + +#### 8.13.2.3 Performance monitoring clock function + +**Symbol:** + +![Figure 8-11: Performance monitoring clock function. The diagram shows a block diagram of the clock function. Input 'NE-RTC' enters a '10-seconds delay' block, which outputs 'PMclock'. Below this block is a '1-second periods' block with output 'MI_1second'. The 'PMclock' signal enters a '15-minute interval counter' block, which outputs 'PMclock15m'. This signal then enters a '24-hour interval counter' block, which outputs 'PMclock24h'. Below the 24-hour counter is a 'Start24h' input. The text 'G.7710-Y.1701(20)-Amd.1(22)_F8-11' is at the bottom right.](85b53faf49a839f512153285c78fbbdb_img.jpg) + +Figure 8-11: Performance monitoring clock function. The diagram shows a block diagram of the clock function. Input 'NE-RTC' enters a '10-seconds delay' block, which outputs 'PMclock'. Below this block is a '1-second periods' block with output 'MI\_1second'. The 'PMclock' signal enters a '15-minute interval counter' block, which outputs 'PMclock15m'. This signal then enters a '24-hour interval counter' block, which outputs 'PMclock24h'. Below the 24-hour counter is a 'Start24h' input. The text 'G.7710-Y.1701(20)-Amd.1(22)\_F8-11' is at the bottom right. + +**Figure 8-11 – Performance monitoring clock function** + +##### Interfaces: + +**Table 8-9 – Performance monitoring clock input and output signals** + +| Input(s) | Output(s) | +|--------------------|---------------------------------------------------| +| NE-RTC
Start24h | PMclock
PMclock15m
PMclock24h
MI_1second | + +##### Processes: + +The performance monitoring clock is a logical entity within the NE providing date and time information and clock signals to performance monitoring functions within the network element. The following requirements apply: + +- 1) The **1-second periods** function shall generate the 1-second signal (MI\_1second) at the end of each 1-second period as indicated by the NE-RTC. +- 2) The **10-second delay** function shall generate the date and time (PMclock), which is 10 s delayed with respect to the NE-RTC. +- 3) The **15-minute interval counter** shall generate 15-minute period indications (PMclock15m), which are aligned with the end of each quarter of an hour period (00:00, 15:00, 30:00, 45:00) with respect to PMclock. The start of a period is equal to the end of the previous period. If the NE-RTC is not reset, each 15-minute period spans 900 one-second periods. +- 4) The **24-hour interval counter** shall generate 24-hour period indications (PMclock24h), which are aligned with the end of a quarter of an hour period (00:00:00, 00:15:00, 00:30:00, ...23:45:00) with respect to PMclock. The start of a period is equal to the end of the previous period. If the NE-RTC is not reset, each 24-hour period spans 86 400 one-second periods. +- 5) The **24-hour interval counter** may be instructed (by means of the Start24h signal) on when to begin the 24-hour period. The default period start time shall be 00:00 on the PMclock. By means of the Start24h signal, it shall be able to begin at the start of any 15-minute period. + +It must be noted that the delay of 10 s is an example, based on the availability definition for SDH. + +## 8.14 Fault event filtering + +### 8.14.1 Provisioning + +The fault event filtering (FEF) function of the fault reporting management requires the provisioning of the FEF information (see clause 12.1.2) to configure which received faults from the atomic function shall be reported out of the transport element. Table 8-10 gives an overview of the provisioning items, including value range and default. The FEF list is a list of faults, which are allowed to be reported for triggering SDN controller-based restoration. Fault in the list should be within all the possible faults of the relevant atomic functions of the managed entity. Possible faults of atomic functions are defined in the transport technology-specific Recommendations. + +**Table 8-10 – FEF provisioning** + +| Provisioning | Value range | Default | +|-----------------------------|--------------------------|------------| +| FEF list per managed entity | Managed entity-dependent | Empty list | + +## 8.15 Administrative state + +The Administrative State is defined in clause 8.1.1.3 of [ITU-T X.731], and consists of the following three values: + +- LOCKED +- SHUTTING DOWN +- UNLOCKED + +Events that trigger the transition between the state values of the Administrative state are defined in clause 7.1.3 of [ITU-T X.731]. Figure 8-12 is Figure 3 of [ITU-T X.731] illustrating the valid transition of the Administrative state. + +![Figure 8-12 – Administrative state diagram. The diagram shows three states: UNLOCKED, SHUTTING DOWN, and LOCKED. Transitions are triggered by events: Unlock, Lock, Shut down (if idle), Shut down, Last user quit, and User quit. Transitions from UNLOCKED to LOCKED are triggered by Lock. Transitions from UNLOCKED to SHUTTING DOWN are triggered by Shut down (if idle). Transitions from SHUTTING DOWN to UNLOCKED are triggered by Unlock. Transitions from SHUTTING DOWN to LOCKED are triggered by Lock or Last user quit. Transitions from LOCKED to UNLOCKED are triggered by Unlock. Self-loops on UNLOCKED and SHUTTING DOWN are triggered by User quit.](efbdfb3d9d5a7a7782ef29e131f9f280_img.jpg) + +``` +stateDiagram-v2 + [*] --> UNLOCKED + UNLOCKED --> UNLOCKED : User quit + UNLOCKED --> LOCKED : Lock + UNLOCKED --> SHUTTING_DOWN : Shut down (if idle) + SHUTTING_DOWN --> UNLOCKED : Unlock + SHUTTING_DOWN --> LOCKED : Lock + SHUTTING_DOWN --> LOCKED : Last user quit + SHUTTING_DOWN --> SHUTTING_DOWN : User quit +``` + +Figure 8-12 – Administrative state diagram. The diagram shows three states: UNLOCKED, SHUTTING DOWN, and LOCKED. Transitions are triggered by events: Unlock, Lock, Shut down (if idle), Shut down, Last user quit, and User quit. Transitions from UNLOCKED to LOCKED are triggered by Lock. Transitions from UNLOCKED to SHUTTING DOWN are triggered by Shut down (if idle). Transitions from SHUTTING DOWN to UNLOCKED are triggered by Unlock. Transitions from SHUTTING DOWN to LOCKED are triggered by Lock or Last user quit. Transitions from LOCKED to UNLOCKED are triggered by Unlock. Self-loops on UNLOCKED and SHUTTING DOWN are triggered by User quit. + +Figure 8-12 – Administrative state diagram (from Figure 3 of [ITU-T X.731]) + +Note that in the state transition diagram, the events "Unlock", "Lock" and "Shut down" could be initiated on the request of a management control system (MCS), such as SDN controller or EMS, etc. + +Some resources exhibit only a subset of the possible administrative state values. Some resources cannot be locked, and hence exhibit only the *UNLOCKED* state. Other resources cannot be shut down gracefully, and hence do not exhibit the *SHUTTING DOWN* state. In general, the atomic functions in the transport equipment (such as those specified in [b-ITU-T G.798], [b-ITU-T G.8021] and [b-ITU-T G.8121.x] series) do not exhibit the *SHUTTING DOWN* state; and the *LOCKED* state is applicable only to some adaptation functions. + +The actual subset of administrative state values supported varies from one type of resource to another and is specified in the technology-specific Recommendations. + +Note that in some technology-specific Recommendations, the terms *NORMAL* or *NOT\_LOCKED* have been used in place of the *UNLOCKED* state. + +An operator can administratively lock a server layer trail in order to perform maintenance operations on the trail. When a server layer trail is locked, the user traffic on all its client layer connections is not allowed to be transmitted to nor received from that trail. In this situation, an alarm shall not be raised on the client layer connections due to the administrative blocking of user traffic. To lock a server layer trail, the locking instruction (i.e., administrative state is *LOCKED*) shall be applied to the adaptation function(s) at the end(s) of the server layer trail, as defined in clause 5.6.3 of [ITU-T G.806]. Whether the EMF will send administrative lock instruction(s) to the adaptation function or individual client CPs, will be specified in the technology-specific equipment specification. + +An operator can administratively lock a tandem connection in order to perform maintenance operations on the tandem connection. When a tandem connection is locked, the user traffic is not allowed to be transmitted on the tandem connection. In this situation, an alarm shall not be raised on the tandem connection due to the administrative blocking of the tandem connection. To lock a tandem connection, the locking instruction (i.e., administrative state is LOCKED) shall be applied to the adaptation function(s) at the end(s) of the tandem connection, as defined in clause 5.6.3 of [ITU-T G.806]. + +Appendix IV provides examples for applying the administrative states on a server layer trail and tandem connection monitoring (TCM). + +# 9 Account management + +No transport specific account management specification is specified in this Recommendation. + +# 10 Performance management + +Performance management provides functions to evaluate and report upon the behaviour of telecommunication equipment and the effectiveness of the network, or NE. Its role is to gather and analyse statistical data for the purpose of monitoring and correcting the behaviour and effectiveness of the network, NEs or other equipment, and to aid in planning, provisioning, maintenance and the measurement of quality. As such, it is carrying out the performance measurement phase of [ITU-T M.20]. + +The requirements for the performance monitoring functions are specified in clause 10.2. These requirements are based on the performance management applications, described in clause 10.1. + +## 10.1 Performance management applications + +The four basic performance management applications according to [ITU-T M.3400] are: + +### - *Performance quality assurance* + +Performance quality assurance supports decision processes that establish the quality measures that are appropriate to the area of performance management. + +### - *Performance monitoring* + +Acute fault conditions will be detected by alarm surveillance methods. Very low rate, or intermittent, error conditions in multiple equipment units may interact resulting in poor service quality and may not be detected by alarm surveillance. Performance monitoring is designed to measure the overall quality, using monitored parameters in order to detect such degradation. It may also be designed to detect characteristic patterns of impairment before signal quality has dropped below an acceptable level. + +### - *Performance management control* + +Performance management control supports the transfer of information to control the operation of the network in the area of performance management. For transport performance monitoring, this application includes the setting of thresholds and data analysis algorithms and the collection of performance data, but has no direct effect on the managed network. + +### - *Performance analysis* + +Performance data may require additional processing and analysis in order to evaluate the performance level of the entity. The NE may be capable of carrying out part of the analysis of the data before a report is sent to the TMN. + +Within the scope of this Recommendation, i.e., the equipment management functions inside the NE, the applications are limited to the collection and reporting of performance data. This performance data is gathered, pre-processed and partly analysed in the NE for the purpose of maintenance, bringing-into-service, quality of service, reporting and thresholding. + +### 10.1.1 Concepts of "near-end" and "far-end" + +Performance monitoring is a process consisting of performance monitoring event processes and performance monitoring data collection and history processes. + +Within performance monitoring, the concepts of "near-end" and "far-end" are used to refer to performance monitoring information associated with the two directions of transport of a bidirectional trail. For a bidirectional trail from A to Z: + +- at node A, the near-end information represents the performance of the unidirectional trail from Z to A, while the far-end information represents the performance of the unidirectional trail from A to Z; +- at node Z, the near-end information represents the performance of the unidirectional trail from A to Z, while the far-end information represents the performance of the unidirectional trail from Z to A; +- at an intermediate node I in the unidirectional trail A to Z, the near-end information represents the performance of the unidirectional trail segment from A to I, while the far-end information represents the performance of the unidirectional trail from Z to A; +- at an intermediate node I in the unidirectional trail Z to A, the near-end information represents the performance of the unidirectional trail segment from Z to I, while the far-end information represents the performance of the unidirectional trail from A to Z. + +At either end of the trail (A or Z), the combination of near-end and far-end information presents the performance of the two directions of the trail. + +At an intermediate node in the trail (I), the combination of far-end information in the trail signal from A to Z, and far-end information in the trail signal from Z to A, presents the performance of the two directions of the trail. + +For maintenance or performance purposes, not only the measurements themselves are of importance, but also the locations where these measurements are done. Single-ended maintenance (SEM) is the ability to supervise both directions of the signal transmission from a single end of the connection. This is of particular importance if one end of the connection is terminated in an "unmanaged NE". + +![Figure 10-1: Single-ended maintenance through far-end monitoring. The diagram consists of two parts. The left part shows a network element (NE) A connected to a network element (NE) Z. NE A contains a monitoring (Mon) block and is connected to an operating system (OS). NE Z is labeled 'unmanaged' and also contains a Mon block. Arrows show Z→A info being monitored in NE Z and sent to the OS in NE A, while A→Z info is monitored in NE A but cannot be obtained by the OS. The right part shows a similar setup, but with a dashed arrow indicating that A→Z info is conveyed from NE Z to the OS in NE A via remote information embedded in the transmission signal.](8bd7adf738ea4b7e65e0d6f67e122d55_img.jpg) + +The diagram illustrates two scenarios for single-ended maintenance (SEM) through far-end monitoring. In the left scenario, NE A is connected to an unmanaged NE Z. NE A contains a monitoring (Mon) block and is connected to an operating system (OS). NE Z also contains a Mon block. Arrows indicate that Z→A information is monitored in NE Z and sent to the OS in NE A, while A→Z information is monitored in NE A but cannot be obtained by the OS. In the right scenario, the A→Z information is conveyed from NE Z to the OS in NE A via remote information embedded in the transmission signal. + +The OS is unable to obtain the A→Z info, monitored in NE Z. + +Via remote information embedded in the transmission signal the A→Z info is conveyed to the OS. + +G.7710-Y.1701(20)-Amd.1(22)\_F10-1 + +Figure 10-1: Single-ended maintenance through far-end monitoring. The diagram consists of two parts. The left part shows a network element (NE) A connected to a network element (NE) Z. NE A contains a monitoring (Mon) block and is connected to an operating system (OS). NE Z is labeled 'unmanaged' and also contains a Mon block. Arrows show Z→A info being monitored in NE Z and sent to the OS in NE A, while A→Z info is monitored in NE A but cannot be obtained by the OS. The right part shows a similar setup, but with a dashed arrow indicating that A→Z info is conveyed from NE Z to the OS in NE A via remote information embedded in the transmission signal. + +Figure 10-1 – Single-ended maintenance through far-end monitoring + +The left-hand side of Figure 10-1 shows the unmanaged NE Z, whose measurements are inaccessible by the OS. The right-hand side shows the case where NE Z relays back its results (known as remote or backward information) to NE A. This backward information is post-processed (known as far-end monitoring) by NE A. The far-end monitoring results are accessible by the OS. + +Related to the previously mentioned measurements, far-end monitoring is possible for BBE as the backward information contains the number of EBs (REI, BEI). Far-end monitoring is also possible for SES as the backward information contains an indication of a detected defect (RDI, BDI). Far-end monitoring for PJE is not possible as there is no backward information defined for these events. + +### 10.1.2 Maintenance + +The fault management supervision and validation processes (see clauses 7.2.1.1 and 7.2.1.2) describe an effective method to detect and analyse disturbances, and to provide an appropriate indication of the fault condition to maintenance personnel. The described processes, however, are not able to detect and report all causes leading to degraded performance. Maintenance measurements are required to detect additional error causes. + +- In order to be able to do preventive maintenance, it is required to perform signal quality trend analysis. When the quality appears degraded, maintenance personnel may be instructed to replace or repair the degraded equipment before a failure is declared. Signal quality trend analysis is performed on signal quality maintenance measurements at the sink function. + - For circuit layer: These measurements are based on transmitted block count (TBC), errored block count (EBC), block delay (BD) and calculated errored block ratio ( $EBR = EBC/TBC$ ), background block count (BBC), background block errors (BBE) and block delay variation (BDV). A block is a set of consecutive bits – including an error detection code (EDC) – associated with the connection; each bit belongs to one, and only one, block. Consecutive bits may not be contiguous in time. An errored block (EB) is a block with one or more EDC violations. A BBE is an EB not occurring as part of a severely errored second (SES, see below). A background block (BB) is a transmitted block (TB) not occurring as part of an SES. The number of BBEs and BBs is summed over 15-minute and 24-hour intervals, over which the trend analysis is performed. The TBC is a circuit signal type and bit rate dependent, fixed value. Summary statistics (such as minimum, average, and maximum) for BD and BDV are derived over 15-minute and 24-hour interval for continuous monitoring. + - For packet layer: A block is a non-drop eligible frame or packet with a specific priority associated with the connection. The measurements are based on transmitted block count (TBC, also known as TF), lost block count (LBC, also known as LF), block delay (BD, also known as FD) and the calculated lost block ratio ( $LBR = LBC/TBC$ , or $FLR = LF/TF$ ), background block count (BBC), background block error (BBE) and block delay variation (BDV, also known as FDV). An LB (also known as LF) is a lost block/frame. A BBE is a LB not occurring as part of a severely errored second (SES). The number of BBEs is summed over 15-minute and 24-hour intervals, over which the trend analysis is performed. The TBC (i.e., TF) is a variable value. Summary statistics (such as minimum, average, and maximum) for BD (i.e., FD) and BDV (i.e., FDV) are derived over 15-minute and 24-hour intervals for continuous monitoring. +- In order to locate the source of intermittent error conditions, e.g., short bursts of bit errors or lost frames or packets, it is required to measure these error conditions at various places in the network. These bursts cause a high EBR or LBR, or result in the declaration of framing defects (e.g., dLOF, dLOP). Fault management is not able to alert maintenance personnel in these cases because the defects do not persist long enough to become a failure. + +- Severely errored second (SES): The maintenance measurement is based on the detection of these bursts. An SES is declared when, during one second, the EBR or LBR exceeds a threshold, or when a defect second (DS) is declared. + +The number of SESs is summed over 15-minute and 24-hour intervals. The analysis of these reports may be an aid to locate the error source. + +- In order to determine whether the performance level is normal, degraded or unacceptable, it is required to set appropriate performance limits. For example, according to [ITU-T M.2101], the degraded and unacceptable performance limits are expressed as threshold values for the number of background block errors (BBEs), the number of errored seconds (ESs) and the number of SESs, summed over 15-minute intervals and 24-hour intervals. An ES is declared when, during one second, there are one or more EBs or LBs detected, or when a defect is declared. When a threshold report (see clause 10.1.7) is generated, maintenance personnel may be driven to perform additional network performance analysis. +- In order to locate the source that causes the generation of jitter and wander, e.g., due to a wrongly selected timing reference source, it is required to measure these error conditions. Jitter and wander can be measured directly by connecting the appropriate measurement equipment to the interface port. This method, however, may require maintenance personnel being present at the measurement location. An alternative approach, for example, is to measure the positive and negative pointer justification events (PJEs). These events may be an indication of a wrongly applied timing source. The PJEs are summed over 24-hour intervals. The analysis of these reports may be an aid to locate the error source. +- In order to locate equipment that needs adjustment or retuning, e.g., to limit drift or oscillation, it is required to do gauge measurements at or near the equipment. Examples of gauge measurements are the (optical) power level, the gain and the temperature. These gauges are measured periodically. Maintenance personnel may request a snapshot, in which case the current value is made available at the workstation or craft terminal. The NE keeps a record of the highest value and the lowest value of the gauge over 15-minute and 24-hour measurement intervals. The analysis of these gauge tidemark reports may drive maintenance personnel to readjust the equipment. + +It must be noted that the previously described error causes are indeed detected by the indicated maintenance measurements. The reverse, however, is not always true: not every SES indicates a burst error; an increasing number of BBEs does not necessarily indicate degraded equipment; a large amount of PJEs need not be caused by a wrong timing reference source. Therefore, care must be taken with the analysis of the performance maintenance reports. + +### 10.1.3 Bringing-into-service + +Bringing-into-service (BIS) tests should be long-term measurements of new equipment, using a pseudo-random generator and receiver. However, for practical reasons the measurements may be reduced to a quick measurement and the assessment completed with in-service performance monitoring available in the network element. BIS methods for paths are defined in [ITU-T M.2110]. + +The BIS performance objectives for equipment supporting circuit layers, e.g., SDH paths, PDH paths, OTN ODU paths, etc., are based on the collection of ESs, SESs and BBEs. The BIS performance objectives for equipment supporting packet layers, e.g., ETH paths are based on the collection of ESs, SESs and BBEs or a subset of those. These measurements are evaluated in the management system and/or the NE over periods of 15 minutes, 2 hours, 1 day and 7 days. For the declaration of an SES, see the technology-specific ITU-T Recommendations, e.g., [ITU-T M.2101] defines the SDH BIS performance objectives in full detail. + +The 15-minute and 24-hour registers should provide the capability to be reset to zero at the conclusion of the BIS intervals. If the history is stored as a log record, the capability to delete the log entries should be provided. + +### 10.1.4 Quality of service + +Quality of service (QoS) deals with service quality criteria stated in service provider specifications or service level agreements (SLAs) between service providers, or service providers and customers. In general, SLAs are applicable when there is a relationship, e.g., between a customer and an operator, or between a lead operator and several carriers. At a minimum, the SLA contains specifications for the grade of service to be delivered. Because of service provider specifications and SLA contracts, it is important for the service provider to measure the quality level during the "bringing the connection into service" phase. Once the NE and the connection is in service, both the service provider and the service customer need in-service performance measurements to validate the specifications or SLAs. + +QoS measurements are performed once the NE and connections are in-service. These measurements cannot be PRBS-based, as the payload is reserved for the client signal. The QoS measurements are used to evaluate and validate the performance objectives to be met over an evaluation period of typically 30 consecutive days (one month). For example, Table 10-1 lists the performance parameters used in SDH technology, defined in [ITU-T G.826], [ITU-T G.827], [ITU-T G.828] and [ITU-T G.829]. The right column specifies the measurements inside the NE. + +**Table 10-1 – QoS performance parameters and NE measurements** + +| Performance parameters | NE measurements (see Note) | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Errored second ratio (ESR) is defined as the ratio of ESs in available time to total seconds in available time during a fixed measurement interval. | The NE shall count the number of ESs during 24-hour intervals. | +| Severely errored second ratio (SESR) is defined as the ratio of SESs in available time to total seconds in available time during a fixed measurement interval. | The NE shall count the number of SESs during 24-hour intervals. | +| Background block error ratio (BBER) is defined as the ratio of BBEs in available time to total blocks in available time during a fixed measurement interval. The count of total blocks excludes all blocks during SESs. | The NE shall count the number of BBEs during 24-hour intervals. | +| Severely errored period intensity (SEPI) is defined as the number of SEP events in available time, divided by the total available time in seconds during a fixed measurement interval. Note that another name for SEP is CSES period. | The consecutive severely errored second (CSES) period is defined as a sequence of between three to nine consecutive SESs. The sequence is terminated by a second, which is not an SES. The NE shall time-stamp and log the start of the CSES event. | +|

The availability ratio (AR) is defined as the ratio of the total available time to the duration of the fixed measurement interval.

The total available time in the 24-hour interval is calculated as the difference between the number of seconds in the 24-hour interval (i.e., 86 400) and the number of unavailable seconds.

|

The NE shall administer the total unavailable time in one or two methods. The first method counts the number of unavailable seconds (UAS) during 24-hour intervals. The second method logs the begin time (BUT) and end time (EUT) of unavailable periods.

| +|

The outage intensity (OI) is defined as the reciprocal of the average duration of available time during a fixed measurement interval.

The outage intensity over a 30-day interval is calculated as the quotient of the number of unavailable periods in the 30-day interval and the total available time of the 30-day interval.

| As for the AR, the NE shall log the BUT and EUT. | + +**Table 10-1 – QoS performance parameters and NE measurements** + +| Performance parameters | NE measurements (see Note) | +|-------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------| +| NOTE – The NE measurements outlined here are only for QoS purposes. The full list and measurement intervals are to be found in clause 10.1.6.1. | | + +For QoS purposes, not only the measurements themselves are of importance, but also the locations where these measurements are done. As for maintenance measurements, described in clause 10.1.2, it is important to supervise both directions of the signal transmission from a single end of the connection. QoS measurements are also needed at any intermediate point of the connection. This is of particular importance if the lead operator is in the middle of the connection without management access to the end points. + +Figure 10-2 outlines the bidirectional connection A-Z, passing an intermediate node I. The three NEs A, I and Z have, independently, the capability to supervise the bidirectional connection. In NE A, the near-end monitor (NE-Mon) and far-end monitor (FE-Mon) calculate the performance parameters of the $Z \rightarrow A$ and $A \rightarrow Z$ respectively. Likewise, in NE Z the NE-Mon and FE-Mon calculate the $A \rightarrow Z$ and $Z \rightarrow A$ parameters. In NE I there are two FE-monitors. The upper one in Figure 10-2 is connected to the $A \rightarrow Z$ signal and monitors non-intrusively its far-end information, being $Z \rightarrow A$ . The lower one monitors non-intrusively the far-end $A \rightarrow Z$ information. In this way all three independent NEs, and their independent management systems, are able to do bidirectional QoS measurements for the $A \leftrightarrow Z$ connection. + +![Diagram of single point QoS measurements showing three network elements (NE A, NE I, NE Z) connected in a bidirectional path. NE A and NE Z each have a Near-End Monitor (NE-Mon) and a Far-End Monitor (FE-Mon). NE I has two FE-Monitors. Arrows show signal flow and monitoring points. Below each NE is an Optical System (OS A, OS I, OS Z) receiving 'A<->Z info'.](74b540f71bcf10a8a66b2f01ea8c08ec_img.jpg) + +The diagram illustrates a bidirectional network connection between NE A and NE Z, passing through an intermediate node NE I. + +- **NE A (Left):** Contains an NE-Mon and an FE-Mon. It receives 'Far-End info Z→A' from NE Z via a dashed line. It sends 'A↔Z info' to OS A. + +- **NE I (Middle):** Contains two FE-Monitors. The upper FE-Mon monitors the $A \rightarrow Z$ signal for $Z \rightarrow A$ far-end info. The lower FE-Mon monitors the $Z \rightarrow A$ signal for $A \rightarrow Z$ far-end info. It sends 'A↔Z info' to OS I. + +- **NE Z (Right):** Contains an NE-Mon and an FE-Mon. It receives 'Far-End info A→Z' from NE A via a dashed line. It sends 'A↔Z info' to OS Z. + +Solid lines represent the main signal paths, while dashed lines represent the monitoring and management information flows. + +Diagram of single point QoS measurements showing three network elements (NE A, NE I, NE Z) connected in a bidirectional path. NE A and NE Z each have a Near-End Monitor (NE-Mon) and a Far-End Monitor (FE-Mon). NE I has two FE-Monitors. Arrows show signal flow and monitoring points. Below each NE is an Optical System (OS A, OS I, OS Z) receiving 'A<->Z info'. + +**Figure 10-2 – Single point QoS measurements** + +### 10.1.5 Availability + +The previous definitions are based on the concept of available time, which is defined as follows: + +- A period of unavailable time begins at the onset of $x$ consecutive SES events. These $x$ seconds are considered to be part of unavailable time. A new period of available time begins at the onset of $x$ consecutive non-SES events. These $x$ seconds are considered to be part of available time. SEP indicates a severe error condition, which does not result in unavailability. + +Figure 10-3 illustrates the definition of criteria for SDH technology for transition to/from the unavailable state, including the relationship with SEP. For further details, see [ITU-T G.826] and [ITU-T G.828]. It must be noted that for the SDH case, $x = 10$ . + +![Figure 10-3: SDH example of unavailability determination. The diagram shows a timeline of seconds categorized into four types: Severely errored second (SES) represented by a grey box, Severely errored period (SEP) represented by a box with an 'X', Errored second (ES) represented by a box with an 'X', and Error-free second represented by a white box. A sequence of seconds is shown with arrows indicating durations: '10 s' for 'Unavailability detected', '<10 s' for a subsequent period, and another '10 s' for 'Availability detected'. Below the timeline, a long arrow labeled 'Period of unavailable time' spans from the start of the first 10s period to the start of the availability period. A legend on the left defines the box types. The text 'G.7710-Y.1701(20)-Amd.1(22)_F10-3' is in the top right.](7e5f8a1e5575ef87a54c9c091eaaa66d_img.jpg) + +Figure 10-3: SDH example of unavailability determination. The diagram shows a timeline of seconds categorized into four types: Severely errored second (SES) represented by a grey box, Severely errored period (SEP) represented by a box with an 'X', Errored second (ES) represented by a box with an 'X', and Error-free second represented by a white box. A sequence of seconds is shown with arrows indicating durations: '10 s' for 'Unavailability detected', '<10 s' for a subsequent period, and another '10 s' for 'Availability detected'. Below the timeline, a long arrow labeled 'Period of unavailable time' spans from the start of the first 10s period to the start of the availability period. A legend on the left defines the box types. The text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-3' is in the top right. + +**Figure 10-3 – SDH example of unavailability determination** + +A bidirectional connection is in the unavailable state if either one, or both directions, are in the unavailable state. This is shown in Figure 10-4. A unidirectional connection is in the unavailable state if that direction is in the unavailable state. + +![Figure 10-4: Example of the unavailable state of a bidirectional connection. The diagram shows three horizontal lines representing 'A→Z direction', 'Z→A direction', and 'Connection'. Rectangles on the lines indicate periods of unavailability. Vertical dashed lines connect these periods across the three lines. A legend at the bottom shows a grey rectangle labeled 'Unavailable state'. The text 'G.7710-Y.1701(20)-Amd.1(22)_F10-4' is in the bottom right.](5801c19431e76330430e92a598cc7a16_img.jpg) + +Figure 10-4: Example of the unavailable state of a bidirectional connection. The diagram shows three horizontal lines representing 'A→Z direction', 'Z→A direction', and 'Connection'. Rectangles on the lines indicate periods of unavailability. Vertical dashed lines connect these periods across the three lines. A legend at the bottom shows a grey rectangle labeled 'Unavailable state'. The text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-4' is in the bottom right. + +**Figure 10-4 – Example of the unavailable state of a bidirectional connection** + +### 10.1.6 Collection + +#### 10.1.6.1 15-minute and 24-hour performance data collection + +The collection of performance data requires timing parameters to sample, measure and report metrics related to performance parameters. + +##### Sampling interval + +The sampling interval defines the period at which network performance data is collected at consistent, predetermined time points. It ensures the continuous and timely capture of performance metrics, enabling accurate assessments of network conditions. During this process, performance parameters such as errored seconds (ES) latency, and packet loss are measured periodically. For example, ES may be sampled every second, allowing early detection of performance degradation and enabling prompt corrective actions. + +##### Measurement interval + +The measurement interval specifies the duration over which sampled performance data is aggregated or statistically processed. It helps manage large volumes of data by summarizing it into meaningful indicators for analysis, anomaly detection and resource management. For instance, latency data collected at one-second intervals can be aggregated into hourly averages, providing valuable insights into hourly performance trends and supporting effective monitoring and planning. + +##### Reporting interval + +The reporting interval defines how often the measured performance data is communicated to network management systems or other stakeholders. This interval can be configured based on operational needs, allowing for either regular, periodic reporting – such as every 15 minutes or 24 hours – or + +event-driven reporting triggered by specific performance thresholds or anomalies. Structured and timely reporting enables prompt decision-making, supports proactive network management, and ensures effective communication among relevant parties. + +##### Uniform time + +Uniform time is a fixed, predefined point within each measurement interval at which a snapshot measurement is taken. It enables a consistent and instantaneous view of network performance across intervals, without requiring data aggregation. This approach facilitates quick diagnostics and synchronization across monitoring systems. + +Table 10-2 summarizes the performance parameters the NE can collect for maintenance and quality of service purposes. This data is reported to the OS. + +**Table 10-2 – Performance data collection** + +| | | Maintenance
(each direction of the transport independently) | Quality of service (Note 1)
(both directions of the transport together) | +|------------------|------------------------------------------------------|-----------------------------------------------------------------------|-----------------------------------------------------------------------------------| +| counts | 15-minute interval
1 current + 16 recent (Note 2) | ES, SES, BBE, BBC, UAS | | +| | 24-hour interval
1 current + 1 recent | ES, SES, BBE, BBC, UAS, PJE | ES, SES, BBE, BBC, SEP, UAS | +| events | | | BUT, EUT, CSES | +| snapshots | 15-minute interval
1 current + 16 recent (Note 2) | gauge value at uniform time | | +| | 24-hour interval
1 current + 1 recent | gauge value at uniform time | | +| tidemarks | 15-minute interval
1 current + 16 recent (Note 2) | gauge highest value, gauge lowest value | | +| | 24-hour interval
1 current + 1 recent | gauge highest value, gauge lowest value | | + +NOTE 1 – This is intended for bidirectional connections. For the case of unidirectional services, the other direction is not taken into account. +NOTE 2 – The North American region may require 32 recent registers for 15-minute measurements. +NOTE 3 – The technology-specific Recommendations may require only a subset of the performance parameters listed in the table. + +##### 15-minute counts + +Performance measurements are counted in a counter per measurement. These counters are called current registers. + +It will be possible to reset an individual current register to zero by means of an external command. It will be possible to reset a collection of near-end and/or far-end registers (BBE, BBC, ES, SES, UAS) via one configuration command on a per TP basis or a group of TPs of the same type. If the TP performs bidirectional monitoring, the bidirectional UAS register shall be reset to zero when either the near-end group or the far-end group registers are reset to zero. + +When history data storage is required, at the end of a 15-minute period, the contents of the current registers are transferred to the first of 16 recent registers, provided that the content is not zero and history storage suppression is not activated. After the transfer to the recent register, the current register shall be reset to zero. When all recent registers are used, the oldest information will be discarded. When history storage suppression (see clause 10.1.6.2) is activated, no transfer to the recent registers takes place when the current register contents are zero. + +##### **24-hour counts** + +The performance measurements are counted in a counter per measurement, independent of the 15-minute counters. These counters are called the current registers. It is up to the NE implementation when to update the register counts. It is not required to be done on a second-by-second basis, e.g., it is allowed to use the 15-minute register values to feed the 24-hour counts (for unidirectional connections only). + +It will be possible to reset an individual current register to zero by means of an external command. It will be possible to reset a collection of near-end and/or far-end registers (BBE, BBC, ES, SES, UAS) via one configuration command on a per TP basis or a group of TPs of the same type. If the TP performs bidirectional monitoring, the bidirectional UAS register shall be reset to zero when either the near-end group or the far-end group registers are reset to zero. + +When history storage is required, at the end of a 24-hour period, for each monitoring event, the contents of the current register are transferred to the recent register, provided that the content is not zero and history storage suppression is not activated. After the transfer to the recent register, the current register shall be reset to zero. When history storage suppression (see clause 10.1.6.2) is activated, no transfer to the recent register takes place when the current register contents are zero. + +##### **Events** + +The performance monitoring events, designated to be logged, are the begin unavailable time (BUT) event, the end unavailable time (EUT) event, and the time-stamped CSES event. + +##### **15-minute snapshot** + +The gauge measurements are stored in a register per measurement once, at a uniform time, within the 15-minute interval (a snapshot). These registers are called current registers. + +At the end of a 15-minute period, the contents of the current registers are transferred to the first of 16 recent registers; the current register shall preserve its value. When all recent registers are used, the oldest information will be discarded. For specific applications, historical data may not be stored, e.g., only when threshold reports (see clause 10.1.7) are used, or when history storage suppression (see clause 10.1.6.2) is activated. + +##### **24-hour snapshot** + +The gauge measurements are stored in a register per measurement once, at a uniform time, within the 24-hour interval (a snapshot). These registers are called current registers. + +At the end of a 24-hour period, for each gauge, the contents of the current register are transferred to the recent register; the current register shall preserve its value. For specific applications, historical data may not be stored, e.g., only when threshold reports (see clause 10.1.7) are used, or when history storage suppression (see clause 10.1.6.2) is activated. + +##### **15-minute tidemarks** + +Gauges are measured periodically within the 15-minute interval. The current 15-minute high tidemark register will contain the maximum value achieved, so far, by the gauge during the 15-minute interval. The current 15-minute low tidemark register will contain the minimum value achieved, so far, by the gauge during the 15-minute interval. + +At the end of a 15-minute period, the contents of the current registers are transferred to the first of 16 recent registers; the current register will be reset to the current gauge value. When all recent registers are used, the oldest information will be discarded. For specific applications, historical data may not be stored, e.g., only when threshold reports (see clause 10.1.7) are used, or when history storage suppression (see clause 10.1.6.2) is activated. + +##### 24-hour tidemarks + +Gauges are measured periodically within the 24-hour interval. The current 24-hour high tidemark register will contain the maximum value achieved, so far, by the gauge during the 24-hour interval. The current 24-hour low tidemark register will contain the minimum value achieved, so far, by the gauge during the 24-hour interval. + +At the end of a 24-hour period, for each tidemark, the contents of the current register are transferred to the recent register; the current register shall be reset to the current gauge value. For specific applications, historical data may not be stored, e.g., only when threshold reports (see clause 10.1.7) are used, or when history storage suppression (see clause 10.1.6.2) is activated. + +##### Gauge measurement + +Gauge measurement is illustrated in Figure 10-5. + +![Figure 10-5 – Gauge measurement. This figure consists of three vertically stacked graphs sharing a common time axis. The top graph shows 'Gauge value' over time, with a blue curve representing the gauge value. It includes horizontal dashed lines for 'Overflow threshold' and 'Underflow threshold'. Green 'X' marks indicate snapshots, and green arrows indicate history storage. The middle graph shows 'High tidemark' over time, with a pink curve representing the high tidemark value. It includes a horizontal dashed line for the 'Overflow threshold'. Pink arrows indicate new tidemark gauge values and out-of-range (OOR) reports. The bottom graph shows 'Low tidemark' over time, with a red curve representing the low tidemark value. It includes a horizontal dashed line for the 'Underflow threshold'. Red arrows indicate new tidemark gauge values and out-of-range (OOR) reports. A legend at the bottom explains the symbols: 'X' for Snapshot, green arrows for History storage, pink arrows for New tidemark gauge value, and red arrows for Out of range (OOR) report (threshold crossing alert). Vertical dashed lines indicate gauge register update periods (e.g., 1 second). Horizontal double-headed arrows labeled 'x sec' indicate measurement intervals.](f22e617a7aef13de5ffd8e390bfda1c3_img.jpg) + +Legend: + +- X Snapshot +- History storage +- New tidemark gauge value +- Out of range (OOR) report (threshold crossing alert) +- Gauge register update period (e.g., = 1 second) +- Threshold + +G.7710-Y1701(20)-Amd.1(22)\_F10-5 + +Figure 10-5 – Gauge measurement. This figure consists of three vertically stacked graphs sharing a common time axis. The top graph shows 'Gauge value' over time, with a blue curve representing the gauge value. It includes horizontal dashed lines for 'Overflow threshold' and 'Underflow threshold'. Green 'X' marks indicate snapshots, and green arrows indicate history storage. The middle graph shows 'High tidemark' over time, with a pink curve representing the high tidemark value. It includes a horizontal dashed line for the 'Overflow threshold'. Pink arrows indicate new tidemark gauge values and out-of-range (OOR) reports. The bottom graph shows 'Low tidemark' over time, with a red curve representing the low tidemark value. It includes a horizontal dashed line for the 'Underflow threshold'. Red arrows indicate new tidemark gauge values and out-of-range (OOR) reports. A legend at the bottom explains the symbols: 'X' for Snapshot, green arrows for History storage, pink arrows for New tidemark gauge value, and red arrows for Out of range (OOR) report (threshold crossing alert). Vertical dashed lines indicate gauge register update periods (e.g., 1 second). Horizontal double-headed arrows labeled 'x sec' indicate measurement intervals. + +Figure 10-5 – Gauge measurement + +For each measurement interval, the gauge measurement at every second is used to update the high tidemark and low tidemark. If this update results in a new high tidemark and/or new low tidemark, the new high/low tidemark will be compared with the corresponding threshold value. For the 15-min (or 24-hr) snapshot, the gauge measurement is taken uniformly once per 15-min (or 24-hr). + +##### Register attributes + +The recent registers include a *time-stamp* attribute to indicate the end of the measurement interval. + +The current and recent registers, holding counter values, include the *elapsed time* attribute to indicate how many seconds of the interval have been processed (so far). The elapsed time attribute will be initialized to zero at the start of the current interval. The nominal value of the elapsed time attribute is 900 s for a 15-minute interval, and 86'400 s for a 24-hour interval. Deviations to the nominal value can be caused by the following occurrences: + +- The register belongs to the first (last) interval of the measurement, while the measurement did not start (stop) at an interval boundary. +- The start of the new interval is not exactly 900 s (or 86'400 s) later than the start of the current interval (see clause 8.13.1.1). +- The real-time clock makes a time adjustment caused by the alignment with an external time source (see clause 8.13.2.2). +- An outage condition prevents the collection of performance data, e.g., lost PM data in equipment. +- An incoming alignment error (IAE) event suppresses the performance data collection for the current and previous second. IAE does not stop the elapsed time counter. + +The current and recent registers include a *suspect interval flag* to indicate that the performance data may not be reliable. Some reasons for this occurring are: + +- The register belongs to the first or last interval of the measurement. +- The register belongs to an interval during which the measurement is suspended or resumed. +- The current register, designated for a counter, is reset by an external command. +- The recent register, designated for a counter, holds an elapsed time attribute value, which deviates more than 10 s with the nominal value. +- The register, designated for a snapshot or tidemark, contains no data, e.g., due to outage conditions. +- The register, designated for a tidemark, belongs to an interval during which the periodical gauge measurements are not possible, e.g., due to outage conditions. + +[ITU-T Q.822] contains more examples of conditions that raise the suspect flag. + +#### 10.1.6.2 History storage suppression + +History storage suppression deals with the limited storage of performance data in the MIB. + +For counts this mechanism is known as zero suppression. Zero suppression is described in [ITU-T Q.822]. + +Zero suppression is defined as follows: + +- any 15-minute or 24-hour period in which all collected data is equivalent to zero; and +- the invalid data/suspect flag is not set. + +Other behaviours to note: + +- When the 15-minute or 24-hour period completes the period, the data is checked. + +- If no measurement occurred for a period (e.g., performance monitoring turned-off/locked, performance monitoring disabled, resource monitoring controlled by port mode), then the current data values are undefined, and history records are not created at the end of period. + +NOTE – Port mode is applicable only to SDH and PDH and superseded for new development (e.g., OTN). See Appendix III. + +- Transitions to/from the 'locked' state and transitions to/from the 'disabled' state cause a current period to be marked invalid/suspect. + +The history storage suppression mechanism for gauges is for further study. + +By applying history storage suppression, the effective history storage capacity would be larger than 4 hours (i.e., 16 recent registers of 15 minutes each), as it can be expected that the majority of the counts will be zero. Another advantage is the limited history data transfer over the Q-interface. + +### 10.1.7 Reporting + +#### 10.1.7.1 Polling + +Performance data polling means that the MC system obtains the performance data through a single or periodical query, and the NE reports the performance data after receiving the query request from the MC system. Polling is the conventional way for the MC system to get the 15-minute or 24-hour interval performance data. Before the query from the MC system, usually a performance task has been established on the NE, and the performance data would be collected and stored based on the performance task. + +For a single query, the requested performance data can be all the performance data collected at a specific time range or the incremental data since the last report. When the MC system periodically sends query requests to an NE to obtain performance data, the NE reports the incremental performance data for each query request. The period of querying could be set on the MC system in advance. For all managed NEs, the MC system query the performance data by polling. + +#### 10.1.7.2 Streaming + +Performance data streaming means that an NE proactively reports the performance data based on the received subscription request. The NE should support the lifecycle management of subscription to performance data, including the creation, deletion and modification of the subscription request. The performance parameters that could be subscribed include the managed object, the performance matrix, the data reporting time interval, etc. + +NE can store the subscribed performance data after they are collected and then send them to the MC system based on the data reporting time interval in the subscription request. When the collection time of the performance matrix is less than the data reporting time interval, the NE needs to send multiple values of the performance matrix within the data reporting time interval to the MC system each time. + +NE can use the data streaming mechanism to send the subscribed performance data to the MC system in real time as performance data stream. Correspondingly, the MC system should be able to receive and store the performance data stream from the managed NE in real time. The MC system needs strong data processing ability if many managed NEs simultaneously transmit performance data stream. The management of data streaming mechanism in [b-ITU-T G.7711] could be referred. + +Streaming could improve the flexibility of performance data reporting. It is mainly used for reporting mass of performance data collected with high frequency, such as when the collection period is less than one minute, or a few seconds. + +Streaming is a real-time method for monitoring and managing network performance by continuously pushing data from network equipment to a centralized monitoring system. Streaming uses a push-based approach for more efficient, timely and customizable data delivery to meet specific network management needs. + +From a network equipment perspective, a streaming system consists of a server (a network element) that continuously streams data to a client (an MC system) that subscribes to and analyses this data. The server gathers, formats and streams performance metrics. The client subscribes to specific streams to receive real-time updates without polling. Figure 10-5bis shows a generic example of the streaming system. + +![Diagram of a generic streaming system showing an MC system and an NE. A downward arrow labeled 'Subscription' goes from the MC system to the NE. An upward arrow labeled 'Streaming data' goes from the NE to the MC system. The diagram is labeled G.7710(25) at the bottom.](e5ded249943a879ef58cae5b6b87c576_img.jpg) + +``` +graph TD; MC[MC system] -- Subscription --> NE[NE]; NE -- Streaming data --> MC; +``` + +G.7710(25) + +Diagram of a generic streaming system showing an MC system and an NE. A downward arrow labeled 'Subscription' goes from the MC system to the NE. An upward arrow labeled 'Streaming data' goes from the NE to the MC system. The diagram is labeled G.7710(25) at the bottom. + +**Figure 10-5bis – A generic example of streaming system** + +##### 10.1.7.2.1 Subscription + +Subscriptions are configurations on the network elements that define how and when streaming data will be delivered to the MC system. The subscriptions are set up via client requests and provide real-time insights into network behaviour and performance by controlling data delivery conditions. + +Subscriptions can be categorized by how they are established on the network element: + +- Configured subscription: Predefined on the network element and maintained continuously active. It persists across network element reboots and streams data without requiring a client to initiate a request each time. +- Dynamic subscription: Created on demand by a client. It streams data only when requested and exists only for the duration of that client's session. + +Having both configured and dynamic subscription options enhances scalability and optimizes resource usage, while ensuring immediate insights if required. + +Subscriptions also have two modes based on the data reporting method: + +- Periodic subscription: Sending data at regular, predefined intervals. The interval can range from seconds to hours (or more if needed) depending on the level of detail required and the acceptable impact on network performance. This predictable, continuous stream of data simplifies trend analysis, performance assessment and operational planning by providing consistent PM data. +- On-change subscription: Sending data only when certain predefined changes occur in monitored performance parameters. This method is highly efficient and data-centric, focusing resources on monitoring significant or potentially critical changes, thereby reducing unnecessary data transmission and enhancing focus on relevant network events. + +Each subscription specifies a structured data path that identifies the exact location of the monitored metric within the network element's data model (e.g., a YANG data tree path). This well-defined path ensures that streaming information can be accurately accessed and interpreted. Clients use these paths to request specific streaming data, enabling flexible and targeted monitoring. + +##### 10.1.7.2.2 Streaming data + +Streaming data would be contained in the report messages (e.g., Notification message) initiated by the network element based on periodic or on-change subscription. Each report message includes key elements that structure its content to be actionable: + +- Subscription ID: Identifies the subscription that triggers the notification, allowing correlation back to the original request. This is crucial when multiple subscriptions are concurrently active. +- Event time: The timestamp indicating when the event occurs. In a periodic reporting, this is the time the streaming data was sampled at the configured interval. In an on-change reporting, this is the exact time a change is detected in the monitored metric. +- Change type: The nature of the change that occurs (e.g., *update*, *delete* or *replace*). An *update* means the value of a metric is changed; a *delete* indicates a specific metric or data path is removed; a *replace* means the entire data structure at the given path will be replaced with new data (the previous data is removed before replacement). A *replace* operation is typically used when a full refresh of a streaming dataset or configuration is required instead of an incremental update. +- Path: The data path of the metric, indicating where that metric is located in the data model of the network element. This allows the MC system to associate the reported metric with its source in a structured way. +- Metric value: The actual measured value of the metric at the time of the event, as identified by the data path. + +Reports can be generated at fixed intervals or on an event-driven basis corresponding to the two subscription modes: + +- Periodic reporting: Sending automatically at the regular intervals defined by a periodic subscription. This provides consistent, ongoing updates on equipment status without any external prompt, enabling continuous monitoring under predictable conditions. It ensures a steady flow of information and efficient use of resources as the network element manages data output according to the configured parameters. +- On-change reporting: Triggered only when a subscribed metric changes state. This selective reporting minimizes unnecessary data transmission and saves network and network element resources. It ensures that network managers are alerted only to significant and relevant changes, enabling quick and focused responses to emerging issues. + +#### 10.1.7.3 Thresholding + +A thresholding mechanism can be used to generate an autonomous event report when the performance of a transport entity falls outside a predetermined level. The general strategy for the use of thresholds, described in [ITU-T M.20], is based on the statistical analysis of performance parameters throughout a given time. As soon as the result of the analysis reaches, or exceeds, a defined threshold, the entity is declared to be at an unacceptable level of performance, or at a degraded level of performance. + +Thresholding for maintenance-based performance parameters is within the scope of this Recommendation. The results of the short-term analysis throughout the evaluation periods (15-minute and 24-hour) are reliable enough to declare the unacceptable (15-minute) or degraded (24-hour) level of performance. It must be noted that additional longer-term analysis for maintenance purposes may be required at the OSs. Thresholding for QoS-based performance parameters is outside the scope of this Recommendation because the statistical analysis throughout the evaluation period (typically 30 days) would require too much data storage capacity in the NE. + +##### 10.1.7.3.1 Threshold setting + +The thresholds may be set in the NE, via the OS. The OS will be able to retrieve and change the settings of the 15-minute and 24-hour thresholds. + +##### 10.1.7.3.2 Threshold reporting + +Three basic methods of threshold reporting are defined: + +- The transient condition method treats each measurement period separately. As soon as a threshold is reached or crossed in a 15-minute/24-hour period, for a given performance measurement, a threshold report (TR) is generated. The transient condition method is applicable for counter measurements. +- The standing condition method is an option for 15-minute periods. The standing condition is raised, and a TR is generated, when the set threshold is reached or crossed. The standing condition is cleared, and a reset threshold report (RTR) is generated, when at the end of the period the current value is below or equal to the reset threshold, provided that there was no unavailable time during that period. The standing condition method is applicable for counter measurements. +- The out of range methods are like the transient condition method, but applicable for gauge measurements. For snapshots and high tidemarks, an overflow condition is determined and an out of range report (ORR) is generated as soon as the gauge value reaches or crosses the threshold. Likewise, for snapshots and low tidemarks, an underflow condition is determined and an out of range report (ORR) is generated as soon as the gauge value is at or below the threshold. The out of range methods are applicable for 15-minute and 24-hour measurements. + +Performance data shall be reportable across the NE/OS interface automatically upon reaching or crossing a performance-monitoring threshold. + +Refer to [ITU-T M.2120] for counter measurements; refer to [b-ANSI T1.231] for gauge measurements. + +##### 10.1.7.3.3 Evaluation for counters + +During each 15-minute period, the value of the counter is compared to the set threshold on a second-by-second basis. For 24-hour periods, the NE shall recognize a threshold crossing within 15 minutes of its occurrence. + +##### 10.1.7.3.4 Evaluation for gauges + +During each 15-minute period, the value of the gauge is compared to the set threshold at the moment a new gauge value becomes available. For 24-hour periods, the NE shall recognize a threshold crossing within 15 minutes of its occurrence. + +## 10.2 Performance monitoring functions + +Figure 10-6 contains the functional model of performance monitoring inside the EMF. The white boxes are the performance monitoring functions (PMFs). Full specifications of the functions are given in subsequent clauses. The intermediate ellipses represent the interconnect options between the PMFs. + +The equipment functional specification defines which (sub) set of PMFs is (to be) supported by the equipment, as well as the quantity of each PMF. For the case where the number of transport atomic functions exceeds the number of performance monitoring resources, selection may be indicated by "performance monitoring connection functions", or by alternative means. This is outside the scope of this Recommendation. For the case where such selectivity is not present or is not required, the interconnection is predefined and can be represented by explicit interconnections between PMFs and atomic functions. + +Although Figure 10-6 allows all possible interconnections, it must be noted that the performance monitoring packages, defined by the technology-specific Recommendations, determine which interconnections are applicable. + +![Figure 10-6 – Performance monitoring inside the EMF. This is a complex block diagram showing the internal architecture of performance monitoring within an Element Management Function (EMF). The diagram is divided into three main horizontal sections: 'Performance monitoring' (top), 'Atomic functions' (middle), and 'Non-atomic functions' (bottom). The 'Performance monitoring' section includes various processing blocks like NPME, AvFu, FPME, AvFb, Delay, Cur15m-c, Cur24h-c, UAT, CSES, SPDF, Cur15m-s, Cur15m-t, Cur24h-t, Cur24h-s, Rec15m-c, Rec24h-c, Rec15m-s, Rec15m-t, Rec24h-t, Rec24h-s, ThrF-st, ThrF-tr, ORF-o, and ORF-u. It shows data flow from input signals (MI_pN_TBC, MI_pN_EBC/LBC, MI_pN_DS, MI_pF_TBC, MI_pF_EBC/LBC, MI_pF_DS, MI_pN_DS, MI_pPJ+, MI_pPJ-) through these blocks to output signals (Reset, Rec15m-c, Cur15m-c, TR, RTR, Thresholds, TR, Threshold, Cur24h-c, events, Subscribed PM data, ORR, Threshold, Cur15m-s, Cur15m-t, Cur24h-t, Rec24h-t, Cur24h-s, Rec24h-s). The 'Atomic functions' section includes a 'SPDF' block and 'Gauges' block. The 'Non-atomic functions' section includes 'MI_Px_XXX' and 'MI_pG_XXX' inputs. A 'Date and time functions' block is shown at the bottom. The diagram also features labels for 'Management applications function' and 'Subscription'.](e2dad48ec062e71202459a9ab82261e4_img.jpg) + +**Performance monitoring** + +MI\_pN\_TBC NES(t) +MI\_pN\_EBC/LBC NSES(t) +MI\_pN\_DS NBBC(t) + +MI\_pF\_TBC FES(t) +MI\_pF\_EBC/LBC FSES(t) +MI\_pF\_DS FBBC(t) +MI\_pN\_DS FBBC(t) + +MI\_pPJ+ MI\_pPJ- + +MI\_pG\_XXX + +MI\_Px\_XXX + +NPME + +AvFu + +uni-events +bi-events + +Cur15m-c + +Reset + +Rec15m-c + +Cur15m-c + +AvFb + +uni-UAT +bi-UAT + +uni-SES +bi-SES + +bi-events +uni-events + +Cur24h-c + +Reset + +Rec24h-c + +Cur24h-c + +Delay + +PJE + +UAT + +ThrF-st + +TR, RTR + +Thresholds + +ThrF-tr + +TR + +Threshold + +Reset + +events + +Subscription + +Subscribed PM data + +SPDF + +P\_XXX + +MI\_P\_XXX + +Gauges + +Cur15m-s + +Rec15m-s + +Cur15m-s + +Cur15m-t + +Rec15m-t + +Cur15m-t + +high + +Low + +ORF-o + +ORR + +Threshold + +ORF-u + +ORR + +Threshold + +Cur24h-t + +Rec24h-t + +Cur24h-t + +Cur24h-s + +Rec24h-s + +Cur24h-s + +Reset + +Management applications function + +Date and time functions + +NE-PMC + +G.7710(25) + +Figure 10-6 – Performance monitoring inside the EMF. This is a complex block diagram showing the internal architecture of performance monitoring within an Element Management Function (EMF). The diagram is divided into three main horizontal sections: 'Performance monitoring' (top), 'Atomic functions' (middle), and 'Non-atomic functions' (bottom). The 'Performance monitoring' section includes various processing blocks like NPME, AvFu, FPME, AvFb, Delay, Cur15m-c, Cur24h-c, UAT, CSES, SPDF, Cur15m-s, Cur15m-t, Cur24h-t, Cur24h-s, Rec15m-c, Rec24h-c, Rec15m-s, Rec15m-t, Rec24h-t, Rec24h-s, ThrF-st, ThrF-tr, ORF-o, and ORF-u. It shows data flow from input signals (MI\_pN\_TBC, MI\_pN\_EBC/LBC, MI\_pN\_DS, MI\_pF\_TBC, MI\_pF\_EBC/LBC, MI\_pF\_DS, MI\_pN\_DS, MI\_pPJ+, MI\_pPJ-) through these blocks to output signals (Reset, Rec15m-c, Cur15m-c, TR, RTR, Thresholds, TR, Threshold, Cur24h-c, events, Subscribed PM data, ORR, Threshold, Cur15m-s, Cur15m-t, Cur24h-t, Rec24h-t, Cur24h-s, Rec24h-s). The 'Atomic functions' section includes a 'SPDF' block and 'Gauges' block. The 'Non-atomic functions' section includes 'MI\_Px\_XXX' and 'MI\_pG\_XXX' inputs. A 'Date and time functions' block is shown at the bottom. The diagram also features labels for 'Management applications function' and 'Subscription'. + +Figure 10-6 – Performance monitoring inside the EMF + +### 10.2.1 Near-end performance monitoring event function – NPME + +Symbol: + +![Figure 10-7: NPME Symbol. A block diagram showing the NPME function. Inputs on the left include MI_pN_DS, MI_pN_EBC or MI_pN_LBC, MI_pN_TBC, MI_1 second, MI_TBmin, and NSESthreshold. These inputs connect to three internal blocks: fl3, fl4, and fl6. fl3 and fl4 both receive MI_pN_DS, MI_pN_EBC or MI_pN_LBC, MI_pN_TBC, and MI_1 second. fl3 also receives MI_TBmin. fl4 also receives NSESthreshold. fl6 receives inputs from fl3 and fl4. The outputs on the right are NBBE(t) from fl6, NBBC(t) from fl6, NES(t) from fl3, and NSES(t) from fl4. A small text 'G.7710-Y.1701(20)-Amnd.1(22)_F10-7' is at the bottom right of the diagram.](3b281ef3b6cc5f8ba97cbc011bfaac79_img.jpg) + +Figure 10-7: NPME Symbol. A block diagram showing the NPME function. Inputs on the left include MI\_pN\_DS, MI\_pN\_EBC or MI\_pN\_LBC, MI\_pN\_TBC, MI\_1 second, MI\_TBmin, and NSESthreshold. These inputs connect to three internal blocks: fl3, fl4, and fl6. fl3 and fl4 both receive MI\_pN\_DS, MI\_pN\_EBC or MI\_pN\_LBC, MI\_pN\_TBC, and MI\_1 second. fl3 also receives MI\_TBmin. fl4 also receives NSESthreshold. fl6 receives inputs from fl3 and fl4. The outputs on the right are NBBE(t) from fl6, NBBC(t) from fl6, NES(t) from fl3, and NSES(t) from fl4. A small text 'G.7710-Y.1701(20)-Amnd.1(22)\_F10-7' is at the bottom right of the diagram. + +Figure 10-7 – NPME + +Interfaces: + +Table 10-3 – NPME input and output signals + +| Input(s) | Output(s) | +|------------------------|-----------| +| MI_pN_DS | NBBE(t) | +| MI_pN_EBC or MI_pN_LBC | NBBC(t) | +| MI_pN_TBC | NES(t) | +| MI_1second | NSES(t) | +| MI_TBmin | | +| NSESthreshold | | + +Processes: + +This function determines, on a per second basis, the number of near-end background block errors (BBE), near-end background block count, and whether an ES and/or SES occurred. + +The TBC, EBC or LBC, and DS performance monitoring primitive signals received from a transport atomic function, are the inputs for the determination of the performance events BBE, BBC, ES, SES. + +For the case where a DS input is not connected, DS shall be assumed to be false. In the case where an EBC input is not connected, EBC shall be assumed to be "0". In the case where a TBC input is not connected, TBC shall be assumed to be "1". + +Figure 10-7 presents the processes and their interconnections within the near-end performance monitoring event (NPME) atomic performance monitoring function. + +**fl3:** A near-end errored second (NES) performance monitoring event signal shall be generated if pN\_DS is set or if pN\_EBC $\geq 1$ ; i.e.: + +$$- \quad NES \leftarrow (pN\_DS = true) \text{ or } (pN\_EBC \geq 1).$$ + +**f14:** A near-end severely errored second (NSES) performance monitoring event signal shall be generated if pN\_DS is set or if $(pN\_EBC \text{ (or } pN\_LBC) \geq NSESthreshold \times pN\_TBC)$ and more than a minimum number of blocks (TBmin) were transmitted; i.e.: + +$$- \quad NSES \leftarrow (pN\_DS = true) \text{ or } ((pN\_TBC \geq TBmin) \text{ and } (pN\_EBC \text{ or } pN\_LBC \geq NSESthreshold \times pN\_TBC)).$$ + +The value of the near-end SES threshold, NSESthreshold, depends on the network layer this NPME is connected to. The value of NSESthreshold is a real value between 0 and 1. + +NOTE – For circuit layers (SDH, PDH, OTN) where the number of blocks within a one-second period is a fixed known value, pN\_TBC is representing this fixed known value. For packet layers (e.g., ETH) where the number of blocks (i.e., frames or packets) within a one-second period is variable, pN\_TBC represents the counted number of transmitted blocks within the one-second period. + +**f16:** The near-end background block error (NBBE) and near-end background block count (NBBC) performance monitoring event signals shall equal pN\_EBC and pN\_TBC resp. if the NSES of that second is not set. Otherwise, NBBE and NBBC shall be zero. + +### 10.2.2 Far-end performance monitoring event function – FPME + +**Symbol:** + +![Block diagram of the Far-end performance monitoring event function (FPME). The diagram shows three processing blocks: f24, f23, and f26. Inputs include MI_pN_DS, MI_pF_DS, MI_pF_EBC or MI_pF_LBC, MI_pF_TBC, MI_1 second, FSESthreshold, and MI_TBmin. Outputs include FSES(t), FES(t), FBBE(t), and FBBC(t).](ee0bf6a260cff72af8f0df0639b6a7c5_img.jpg) + +The diagram illustrates the FPME function. It features three main processing blocks: f24, f23, and f26. + + +- Block f24 receives inputs from MI\_pN\_DS, MI\_pF\_DS, FSESthreshold, and MI\_TBmin. It produces the output FSES(t). +- Block f23 receives inputs from MI\_pF\_DS, MI\_pF\_EBC or MI\_pF\_LBC, and MI\_pF\_TBC. It produces the output FES(t). +- Block f26 receives inputs from MI\_pF\_DS, MI\_pF\_EBC or MI\_pF\_LBC, MI\_pF\_TBC, and MI\_1 second. It produces two outputs: FBBE(t) and FBBC(t). + + The MI\_1 second input is shown as a separate signal entering the bottom of the diagram. + +Block diagram of the Far-end performance monitoring event function (FPME). The diagram shows three processing blocks: f24, f23, and f26. Inputs include MI\_pN\_DS, MI\_pF\_DS, MI\_pF\_EBC or MI\_pF\_LBC, MI\_pF\_TBC, MI\_1 second, FSESthreshold, and MI\_TBmin. Outputs include FSES(t), FES(t), FBBE(t), and FBBC(t). + +**Figure 10-8 – FPME** + +**Interfaces:** + +**Table 10-4 – FPME input and output signals** + +| Input(s) | Output(s) | +|------------------------|-----------| +| MI_pN_DS | FBBE(t) | +| MI_pF_DS | FBBC(t) | +| MI_pF_EBC or MI_pF_LBC | FES(t) | +| MI_pF_TBC | FSES(t) | +| MI_1second | | +| MI_TBmin | | +| FSESthreshold | | + +**Processes:** + +This function determines, on a per second basis, the number of far-end background block errors (BBE), far-end background block count, and whether an ES and/or SES occurred. + +The TBC, EBC or LBC, and DS performance monitoring primitive signals received from an atomic function are the inputs for the determination of the performance events BBE, BBC, ES, SES. + +In the case where a DS input is not connected, DS shall be assumed to be false. For the case an EBC input is not connected, EBC shall be assumed to be "0". In the case where a TBC input is not connected, TBC shall be assumed to be "1". + +Figure 10-8 presents the processes and their interconnections within the far-end performance monitoring event (FPME) atomic performance monitoring function. Note that "far-end" represents either those signals that are called "far-end" or those signals that are called "outgoing". + +**f23:** A far-end errored second (FES) performance monitoring event signal shall be generated if pF\_DS is set or if pF\_EBC $\geq 1$ , and if that second is not a near-end defect second (pN\_DS); i.e.: + +$$- \quad \text{FES} \leftarrow (\text{pN\_DS} = \text{false}) \text{ and } ((\text{pF\_DS} = \text{true}) \text{ or } (\text{pF\_EBC} \geq 1)).$$ + +**f24:** A far-end severely errored second (FSES) performance monitoring event signal shall be generated if pF\_DS is set or if pF\_EBC (or pF\_LBC) $\geq \text{FSESthreshold} \times \text{pF\_TBC}$ and more than a minimum number of blocks (TBmin) were transmitted, and that a second is not a near-end defect second; i.e.: + +$$- \quad \text{FSES} \leftarrow (\text{pN\_DS} = \text{false}) \text{ and } ((\text{pF\_DS} = \text{true}) \text{ or } ((\text{pN\_TBC} \geq \text{TBmin}) \text{ and } (\text{pF\_EBC} \text{ or } \text{pF\_LBC} \geq \text{FSESthreshold} \times \text{pF\_TBC}))).$$ + +The value of the far-end SES threshold, FSESthreshold, depends on the network layer this FPME is connected to. The value of FSESthreshold is a real value between 0 and 1. + +NOTE – For circuit layers (SDH, PDH, OTN) where the number of blocks within a one-second period is a fixed known value, pF\_TBC is representing this fixed known value. For packet layers (e.g., ETH) where the number of blocks (i.e., frames or packets) within a one-second period is variable, pF\_TBC represents the counted number of transmitted blocks within the one-second period. + +**f26:** The far-end background block error (FBBE) and far-end background block count (FBBC) performance monitoring event signal shall equal pF\_EBC and pF\_TBC resp. if the FSES of that second is not set and if that second is not a near-end defect second. Otherwise, FBBE and FBBC shall be zero. + +### 10.2.3 Delay function – Delay + +**Symbol:** + +![Diagram of a delay function. A yellow rectangular box contains a white box labeled 'Delay function'. An arrow labeled 'Input(t)' enters the box from the left, and an arrow labeled 'Output(t-10)' exits the box to the right.](9694add1e3183133a9ddb9f41c48d00e_img.jpg) + +Diagram of a delay function. A yellow rectangular box contains a white box labeled 'Delay function'. An arrow labeled 'Input(t)' enters the box from the left, and an arrow labeled 'Output(t-10)' exits the box to the right. + +G.7710-Y.1701(20)-Amd.1(22)\_F10-9 + +**Figure 10-9 – Delay** + +**Interfaces:** + +**Table 10-5 – Delay input and output signals** + +| Input(s) | Output(s) | +|----------|--------------| +| Input(t) | Output(t-10) | + +##### Processes: + +This function delays the input signal (which is not subject to "availability" processing) by 10 s to align it with the performance monitoring time base which is 10 s delayed from the time of day. + +**Delay function:** The input signal (e.g., PJE) shall be delayed by 10 s to align it with the performance monitoring time base signal for further processing in the history atomic performance monitoring functions. + +### 10.2.4 Unidirectional availability filter function – AvFu + +##### Symbol: + +![Block diagram of the Unidirectional availability filter function (AvFu). The diagram shows five input signals on the left: BBC(t), BBE(t), ES(t), SES(t), and UAT_cmd(t). BBC(t), BBE(t), ES(t), and SES(t) each pass through a 'Delay' block to become BBC(t-10), BBE(t-10), ES(t-10), and SES(t-10) respectively. These four delayed signals then enter switches labeled 'f17'. Each 'f17' switch has a '0' input and a signal input. The outputs of these switches are BBC, BBE, ES, and SES. SES(t) also branches to a block labeled 'f15', which outputs UAT_cmd(t-10). This signal enters a switch labeled 'f18' which has '0' and '1' inputs. The output of 'f18' is UAS. The final output signals on the right are BBC, BBE, ES, SES, UAS, and UAT. A vertical dashed line connects the 'f17' and 'f18' switches. A small text label 'G.7710-Y.1701(20)-Amd.1(22)_F10-10' is at the bottom right of the diagram.](b69a80a8520eebfdd4ad580cd69beb8d_img.jpg) + +Block diagram of the Unidirectional availability filter function (AvFu). The diagram shows five input signals on the left: BBC(t), BBE(t), ES(t), SES(t), and UAT\_cmd(t). BBC(t), BBE(t), ES(t), and SES(t) each pass through a 'Delay' block to become BBC(t-10), BBE(t-10), ES(t-10), and SES(t-10) respectively. These four delayed signals then enter switches labeled 'f17'. Each 'f17' switch has a '0' input and a signal input. The outputs of these switches are BBC, BBE, ES, and SES. SES(t) also branches to a block labeled 'f15', which outputs UAT\_cmd(t-10). This signal enters a switch labeled 'f18' which has '0' and '1' inputs. The output of 'f18' is UAS. The final output signals on the right are BBC, BBE, ES, SES, UAS, and UAT. A vertical dashed line connects the 'f17' and 'f18' switches. A small text label 'G.7710-Y.1701(20)-Amd.1(22)\_F10-10' is at the bottom right of the diagram. + +Figure 10-10 – AvFu + +##### Interfaces: + +Table 10-6 – AvFu input and output signals + +| Input(s) | Output(s) | +|----------|-----------| +| BBE(t) | BBE | +| BBC(t) | BBC | +| ES(t) | ES | +| SES(t) | SES | +| | UAS | +| | UAT | + +#### Processes: + +This function determines whether a one second is unidirectionally available or unavailable, and passes through the (ES, SES, BBE, BBC) input signal's value for seconds in available time. The input signal value in seconds in unavailable time is not output; instead the value "0" is output. This function is applicable for near-end, far-end, near-end outgoing and far-end outgoing information processing. + +Based on the SES event indications, the start and end of UAT is determined. The BBE, BBC, ES and SES information is delayed by 10 s to maintain alignment in time of this information and the UAT indication (UATcmd). + +For the case where the BBE(t) input is not connected, BBE(t) shall be assumed to be "0". For the case where the BBC(t) input is not connected, BBC(t) shall be assumed to be "0". In the case where the ES(t) input is not connected, ES(t) shall be assumed to be "0". In the case where the SES(t) input is not connected, SES(t) shall be assumed to be "0". + +**f15:** Unavailable time command (UAT\_cmd) shall be set if ten consecutive SESs are detected. UAT\_cmd shall be cleared after ten contiguous seconds not being SES. + +A change of the UAT\_cmd shall be reported. + +**delay:** The BBE, BBC, ES and SES event signals shall be delayed by 10 s to align them with the UATcmd signal for further processing in the history atomic performance monitoring functions (see also clause 10.2.3). + +**f17:** The BBE(t-10), BBC(t-10), ES(t-10) and SES(t-10) event signals shall be output in available time; i.e., if UATcmd is false. Otherwise, the value "0" shall be output. + +**f18:** In available time (i.e., if UATcmd is false), the value "0" shall be output via UAS. Otherwise (UATcmd is true), the value "1" shall be output. + +### 10.2.5 Bidirectional availability filter function – AvFb + +Symbol: + +![Block diagram of the Bidirectional availability filter function (AvFb) showing signal flow for BBC, BBE, ES, SES, UAS, and UAT signals with delays and filter blocks f17, f18, f19, and f15.](364054adcd1b427fa259450e006c6b38_img.jpg) + +The diagram illustrates the internal structure of the Bidirectional availability filter function (AvFb). It is divided into two main sections: Direction A/Z and Direction Z/A. + +- Direction A/Z (Top Section):** + - Inputs: BBC(t), BBE(t), ES(t), and SES(t). + - Each input passes through a "Delay" block to produce a delayed signal (e.g., BBC(t-10)). + - The delayed signals for BBC, BBE, ES, and SES enter filter blocks labeled "f17". Each f17 block has a "0" input and a switch symbol. + - The outputs of these f17 blocks are BBC, BBE, ES, and SES. + - The SES(t) input also branches to an "f15" block, which outputs UAT\_cmd(t-10). + - The UAT\_cmd(t-10) signal enters a vertical "f19" block. + - The f19 block outputs a signal that enters an "f18" block. + - The f18 block has "0" and "1" inputs and a switch symbol, producing UAS and UAT outputs. +- Direction Z/A (Bottom Section):** + - Inputs: SES(t), ES(t), BBE(t), and BBC(t). + - Each input passes through a "Delay" block to produce a delayed signal (e.g., SES(t-10)). + - The delayed signals enter filter blocks labeled "f17". + - The outputs of these f17 blocks are SES, ES, BBE, and BBC. + - The ES(t) input also branches to an "f15" block, which outputs UAT\_cmd(t-10). + - This UAT\_cmd(t-10) signal enters the "f19" block from the bottom. + +The f17 blocks in both directions are vertically interconnected, and the f19 block is shared between both directions. The diagram is labeled G.7710-Y.1701(20)-Amd.1(22)\_F10-11. + +Block diagram of the Bidirectional availability filter function (AvFb) showing signal flow for BBC, BBE, ES, SES, UAS, and UAT signals with delays and filter blocks f17, f18, f19, and f15. + +Figure 10-11 – AvFb + +##### Interfaces: + +**Table 10-7 – AvFb input and output signals** + +| Input(s) | Output(s) | +|------------|-----------| +| A/Z_BBE(t) | A/Z_BBE | +| A/Z_BBC(t) | A/Z_BBC | +| A/Z_ES(t) | A/Z_ES | +| A/Z_SES(t) | A/Z_SES | +| Z/A_BBE(t) | Z/A_BBE | +| Z/A_ES(t) | Z/A_BBC | +| Z/A_SES(t) | Z/A_ES | +| Z/A_BBC(t) | Z/A_SES | +| | UAS | +| | UAT | + +#### Processes: + +This function determines whether a one second is bidirectionally available or unavailable, and passes through the (ES, SES, BBE, BBC) input signal's value in seconds in available time. The input signal value in seconds in unavailable time is not output; instead the value "0" is output. + +Based on the SES event indications, the start and end of UAT is determined. The BBE, BBC, ES and SES information is delayed by 10 s to maintain alignment in time of this information and the UAT indication (UATcmd). Note that the A/Z and Z/A direction indication is used here instead of the more common near-end and far-end indications to support performance monitoring at both the trail termination points and intermediate points along the trail. + +In the case where the BBE(t) input is not connected, BBE(t) shall be assumed to be "0". In the case where the BBC(t) input is not connected, BBC(t) shall be assumed to be "0". In the case where the ES(t) input is not connected, ES(t) shall be assumed to be "0". In the case where the SES(t) input is not connected, SES(t) shall be assumed to be "0". + +**f15:** Unavailable time command (UAT\_cmd) shall be set if ten consecutive SESs are detected. UAT\_cmd shall be cleared after ten contiguous seconds not being SES. + +**f19:** Bidirectional unavailable time shall be declared if either the A/Z direction is unavailable or the Z/A direction is unavailable: + +– $UAT \leftarrow A/Z\_UAT\_cmd(t-10)$ or $Z/A\_UAT\_cmd(t-10)$ . + +A change of the UAT shall be reported. + +**delay:** The BBE, BBC, ES and SES signals are delayed by 10 s to align them with the UATcmd signal for further processing in the history atomic performance monitoring functions (see also clause 10.2.3). + +**f17:** The BBE(t-10), BBC(t-10), ES(t-10) and SES(t-10) signals shall be output in available time; i.e., if UAT is false. Otherwise, the value "0" shall be output. + +**f18:** In available time (i.e., if UAT is false), the value "0" shall be output via UAS. Otherwise (UAT is true), the value "1" shall be output. + +### 10.2.6 Consecutive severely errored second function – CSES + +Symbol: + +![Symbol diagram for CSES function. A rectangular block labeled 'CSES' has an input arrow labeled 'SES' entering from the left and an output arrow labeled 'CSES' exiting to the right. A vertical arrow labeled 'PMclock' points upwards into the bottom of the block. Below the block is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-12'.](d510bddda14c44163bbeee33b491a105_img.jpg) + +Symbol diagram for CSES function. A rectangular block labeled 'CSES' has an input arrow labeled 'SES' entering from the left and an output arrow labeled 'CSES' exiting to the right. A vertical arrow labeled 'PMclock' points upwards into the bottom of the block. Below the block is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-12'. + +Figure 10-12 – CSES + +Interfaces: + +Table 10-8 – CSES input and output signals + +| Input(s) | Output(s) | +|----------|-----------| +| SES | CSES | +| PMclock | | + +Processes: + +This function detects a sequence of between 3 to 9 consecutive SESs. The sequence is terminated by a second, which is not an SES. + +The function shall generate a time-stamped CSES event if three consecutive SESs are detected. + +### 10.2.7 Begin/end of unavailable time event generation function – UAT + +Symbol: + +![Symbol diagram for UAT function. A rectangular block labeled 'UAT' has an input arrow labeled 'UAT' entering from the left and two output arrows labeled 'BUT' and 'EUT' exiting to the right. A vertical arrow labeled 'PMclock' points upwards into the bottom of the block. Below the block is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-13'.](f40480872b021d2ac7c29202c199b695_img.jpg) + +Symbol diagram for UAT function. A rectangular block labeled 'UAT' has an input arrow labeled 'UAT' entering from the left and two output arrows labeled 'BUT' and 'EUT' exiting to the right. A vertical arrow labeled 'PMclock' points upwards into the bottom of the block. Below the block is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-13'. + +Figure 10-13 – UAT + +Interfaces: + +Table 10-9 – UAT input and output signals + +| Input(s) | Output(s) | +|----------|-----------| +| UAT | BUT | +| PMclock | EUT | + +Processes: + +This function detects the start and end of unavailable periods. + +The function shall generate a time-stamped begin unavailable time (BUT) event if the UAT state changes from "available" to "unavailable". The function shall generate a time-stamped end unavailable time (EUT) event if the UAT state changes from "unavailable" to "available". + +### 10.2.8 Current 15-minute counter register function – Cur15m-c + +Symbol: + +![Symbol diagram for Cur15m-c function block. Inputs on the left: 'Events' (horizontal arrow), 'Reset' (vertical arrow from top), 'PMclock' and 'PMclock15m' (vertical arrows from bottom). Outputs on the right: 'Current counter value', 'Current elapsed time', 'Current suspect interval flag' (top group); 'End of 15 min period counter value', 'End of 15 min period elapsed time', 'End of 15 min period suspect interval flag' (bottom group). Reference text: G.7710-Y.1701(20)-Amd.1(22)_F10-14.](37806e0fc150d857046ebc7e47893d7a_img.jpg) + +Symbol diagram for Cur15m-c function block. Inputs on the left: 'Events' (horizontal arrow), 'Reset' (vertical arrow from top), 'PMclock' and 'PMclock15m' (vertical arrows from bottom). Outputs on the right: 'Current counter value', 'Current elapsed time', 'Current suspect interval flag' (top group); 'End of 15 min period counter value', 'End of 15 min period elapsed time', 'End of 15 min period suspect interval flag' (bottom group). Reference text: G.7710-Y.1701(20)-Amd.1(22)\_F10-14. + +Figure 10-14 – Cur15m-c + +Interfaces: + +Table 10-10 – Cur15m-c input and output signals + +| Input(s) | Output(s) | +|------------|--------------------------------------------| +| Events | Current counter value | +| PMclock | Current elapsed time | +| PMclock15m | Current suspect interval flag | +| Reset | End of 15 min period counter value | +| | End of 15 min period elapsed time | +| | End of 15 min period suspect interval flag | + +Processes: + +This function accumulates the events over periods of 15 minutes. + +**Current register counter value:** The 15-minute current register shall accumulate the content of the register with the input events. The counter value shall be initialized to zero at the start of a new 15-minute interval. The current register shall be large enough to accumulate all integer numbers from zero to a particular maximum value, which determines the minimum register size for that parameter. The maximum value shall be at least the nominal count of an interval. When the maximum value of the register is reached, the register shall remain at that maximum value until it is reset, or transferred. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register counter value reset:** By means of an external command, it shall be possible to reset the current register counter value to zero. + +**Current register elapsed time:** The current register shall contain an elapsed time indication, indicating how many seconds of the interval have been processed (so far). The elapsed time attribute shall be initialized to zero at the start of the current interval. The current register elapsed time shall be able to indicate at least the elapsed time of the nominal interval; i.e., 900 s. When the maximum value of an elapsed time register is reached, the register shall remain at that maximum value until it is reset, or transferred. + +**Current register suspect interval flag:** The current register suspect interval flag will be set to "true" to indicate that the data stored in the register may not be reliable. The suspect interval flag shall be initialized to "true" for the very first interval of the measurement. The suspect interval flag shall be initialized to "false" at the start of subsequent new 15-minute intervals. During the 15-minute interval period, the suspect flag shall be set when the current register counter value is reset to zero (see also "End of accumulation period"). + +**Report current register:** It shall be possible to report the value of the current register when requested. + +**End of accumulation period:** At the end of the 15-minute accumulation period, the contents of the current register may be transferred to the recent register. Prior to the transfer, the suspect interval flag shall be set if the elapsed time deviates from more than 10 s of the nominal time, being 900 s. After the transfer, the current register shall be initialized. If the NE-RTC (and consequently the PMclock) is set to a time outside the current interval, the end of the 15-minute accumulation period shall be assumed, and the actions as specified above shall be performed. + +### 10.2.9 Current 15-minute snapshot register function – Cur15m-s + +**Symbol:** + +![Symbol diagram for Cur15m-s function. A central box labeled 'Cur15m-s' has two input arrows on the left: 'Gauges' and 'PMclock15m'. It has two output arrows on the right. The top output is labeled 'Current snapshot value' and 'Current suspect interval flag'. The bottom output is labeled 'End of 15 min period snapshot value' and 'End of 15 min period suspect interval flag'. A small note 'G.7710-Y.1701(20)-Amd.1(22)_F10-15' is at the bottom right.](1c79f31a718d63814feb28ab46f64f19_img.jpg) + +Symbol diagram for Cur15m-s function. A central box labeled 'Cur15m-s' has two input arrows on the left: 'Gauges' and 'PMclock15m'. It has two output arrows on the right. The top output is labeled 'Current snapshot value' and 'Current suspect interval flag'. The bottom output is labeled 'End of 15 min period snapshot value' and 'End of 15 min period suspect interval flag'. A small note 'G.7710-Y.1701(20)-Amd.1(22)\_F10-15' is at the bottom right. + +**Figure 10-15 – Cur15m-s** + +**Interfaces:** + +**Table 10-11 – Cur15m-s input and output signals** + +| Input(s) | Output(s) | +|----------------------|----------------------------------------------------------------------------------------------------------------------------------------------| +| Gauges
PMclock15m | Current snapshot value
Current suspect interval flag
End of 15 min period snapshot value
End of 15 min period suspect interval flag | + +**Processes:** + +This function selects one gauge measurement as the current 15-minute snapshot. + +**Current register snapshot value:** The 15-minute current register shall hold the value of one gauge measurement. The gauge measurement shall be selected at a uniform time within the 15-minute interval. The current register's snapshot value shall not be initialized at the start of a new 15-minute interval; instead, it preserves the snapshot value from the previous 15-minute interval. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register suspect interval flag:** The current register suspect interval flag will be set to true to indicate that the data stored in the register may not be reliable. The suspect interval flag shall be initialized to "true" at the start of a 15-minute interval to indicate that no snapshot has been taken yet. The suspect interval flag shall be set to "false" after the snapshot has been taken. + +**Report current register:** It shall be possible to report the value of the current register when requested. + +**End of accumulation period:** At the end of the 15-minute accumulation period, the contents of the current register may be transferred to the recent register, after which the current register shall be initialized. If the NE-RTC (and consequently the PMclock) is set to a time outside the current interval, the end of the 15-minute accumulation period shall be assumed, and the actions as specified above shall be performed. + +### 10.2.10 Current 15-minute tidemark register function – Cur15m-t + +Symbol: + +![Symbol diagram for Cur15m-t function. Inputs: Gauges (left), PMclock15m (bottom). Outputs: Current high tidemark value, Current low tidemark value, Current suspect interval flag (top right); End of 15 min period current high tidemark value, End of 15 min period current low tidemark value, End of 15 min period suspect interval flag (bottom right). Reference: G.7710-Y.1701(20)-Amd.1(22)_F10-16.](4a2b39fa33747a6553031cfe1e0947fa_img.jpg) + +Symbol diagram for Cur15m-t function. Inputs: Gauges (left), PMclock15m (bottom). Outputs: Current high tidemark value, Current low tidemark value, Current suspect interval flag (top right); End of 15 min period current high tidemark value, End of 15 min period current low tidemark value, End of 15 min period suspect interval flag (bottom right). Reference: G.7710-Y.1701(20)-Amd.1(22)\_F10-16. + +Figure 10-16 – Cur15m-tidemark + +Interfaces: + +Table 10-12 – Cur15m-t input and output signals + +| Input(s) | Output(s) | +|----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Gauges
PMclock15m | Current high tidemark value
Current low tidemark value
Current suspect interval flag
End of 15 min period high tidemark value
End of 15 min period low tidemark value
End of 15 min period suspect interval flag | + +Processes: + +This function registers the highest and lowest value of periodic gauge measurements during the current 15-minute interval. + +**Current register high tidemark value:** The current 15-minute high tidemark register shall contain the maximum value achieved, so far, by the gauge during the 15-minute interval. The current register's high tidemark value shall be initialized to the instantaneous gauge value at the start of a new 15-minute interval. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register low tidemark value:** The current 15-minute low tidemark register shall contain the minimum value achieved, so far, by the gauge during the 15-minute interval. The current register's low tidemark value shall be initialized to the instantaneous gauge value at the start of a new 15-minute interval. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register suspect interval flag:** The current register suspect interval flag will be set to true to indicate that the data stored in the register may not be reliable. The suspect interval flag shall be initialized to "false" at the start of a 15-minute interval. During the 15-minute interval period, the suspect flag shall be set when there is a lack of periodic gauge measurements. + +**Report current register:** It shall be possible to report the value of the current register when requested. + +**End of accumulation period:** At the end of the 15-minute accumulation period, the contents of the current register may be transferred to the recent register, after which the current register shall be initialized. If the NE-RTC (and consequently the PMclock) is set to a time outside the current interval, the end of the 15-minute accumulation period shall be assumed, and the actions as specified above shall be performed. + +### 10.2.11 Recent 15-minute register functions – Rec15m-c, Rec15m-s, Rec15m-t + +Symbol: + +![Symbol diagram for Rec15m functions showing 16 recent registers (15 min recent) and inputs: PMclock and End of 15 min period register. The output is Recent 15-minute register. The diagram is labeled G.7710-Y.1701(20)-Amd.1(22)_F10-17.](3b11cc18f8ee769d0076c139dbf81ba3_img.jpg) + +The diagram shows a yellow rectangular block representing the symbol for the Rec15m functions. Inside the block, there is a vertical stack of 16 smaller rectangles, each labeled "15 min recent". The top 15 rectangles are numbered 16 down to 2 on the left, and the bottom one is numbered 1. An arrow labeled "Recent 15-minute register" points upwards from the top of the stack. An arrow labeled "End of 15 min period register" points upwards from the bottom of the stack. An arrow labeled "PMclock" points upwards from the bottom left corner of the block. Below the block, the text "G.7710-Y.1701(20)-Amd.1(22)\_F10-17" is written. + +Symbol diagram for Rec15m functions showing 16 recent registers (15 min recent) and inputs: PMclock and End of 15 min period register. The output is Recent 15-minute register. The diagram is labeled G.7710-Y.1701(20)-Amd.1(22)\_F10-17. + +Figure 10-17 – Rec15m-c, Rec15m-s, Rec15m-t + +Interfaces: + +Table 10-13 – Rec15m-c, Rec15m-s, Rec15m-t input and output signals + +| Input(s) | Output(s) | +|------------------------------------------|-------------------------------| +| End of 15 min period register
PMclock | Recent 15 min register [1:16] | + +Functions/Processes: + +The Rec15m-c function stores the end of 15-min period counter value, elapsed time and suspect interval flag in one of the 16 recent registers. The Rec15m-s function stores the end of 15-min period snapshot value and suspect interval flag in one of the 16 recent registers. The Rec15m-t function stores the end of 15-min period high tidemark value, low tidemark value and suspect interval flag in one of the 16 recent registers. + +**Recent registers:** At the end of the 15-minute period, when history data storage is not suppressed, the end of 15-min period register input shall be transferred to the recent #1 register. Before the data is transferred, any data in the recent #i (i = 1...15) registers shall be transferred to the recent #(i+1) registers. The data in the recent#16 register shall be discarded. + +**Recent register time stamp:** The recent register shall contain a time-stamp indicating the end of the recent interval. + +**Report recent register:** It shall be possible to report the value of the recent registers when requested. + +### 10.2.12 Current 24-hour counter register function – Cur24h-c + +Symbol: + +![Symbol diagram for Cur24h-c function. Inputs: Reset (top), Events (left), PMclock and PMclock24h (bottom). Outputs: Current counter value, Current elapsed time, Current suspect interval flag (top right); End of 24 h period counter value, End of 24 h period elapsed time, End of 24 h period suspect interval flag (bottom right). Reference: G.7710-Y.1701(20)-Amd.1(22)_F10-18.](778a90bfa183fbf83bfe2bf1ed8fa827_img.jpg) + +Symbol diagram for Cur24h-c function. Inputs: Reset (top), Events (left), PMclock and PMclock24h (bottom). Outputs: Current counter value, Current elapsed time, Current suspect interval flag (top right); End of 24 h period counter value, End of 24 h period elapsed time, End of 24 h period suspect interval flag (bottom right). Reference: G.7710-Y.1701(20)-Amd.1(22)\_F10-18. + +Figure 10-18 – Cur24h-c + +Interfaces: + +Table 10-14 – Cur24h-c input and output signals + +| Input(s) | Output(s) | +|------------|------------------------------------------| +| Reset | Current counter value | +| Events | Current elapsed time | +| PMclock | Current suspect interval flag | +| PMclock24h | End of 24 h period counter value | +| | End of 24 h period elapsed time | +| | End of 24 h period suspect interval flag | + +Processes: + +This function accumulates the events over periods of 24 hours. + +**Current register counter value:** The 24-hour current register shall accumulate the content of the register with the input events. The counter value shall be initialized to zero at the start of a new 24-hour interval. The current register shall be large enough to accumulate all integer numbers from zero to a particular maximum value, which determines the minimum register size for that parameter. The maximum value shall be at least the nominal count of an interval. When the maximum value of the register is reached, the register shall remain at that maximum value until it is reset, or transferred. Current data may be lost during failure conditions within the equipment and its power feeding. + +NOTE 1 – Although all event counts should (ideally) be actual counts for the 24-hour filtering periods, it is recognized that it might be desirable to limit register sizes. + +NOTE 2 – It is up to the NE implementation to update the register counts. It is not required that it be done on a second-by-second basis. An update once every 15 minutes would be sufficient. + +**Current register counter value reset:** By means of an external command it shall be possible to reset the current register counter value to zero. + +**Current register elapsed time:** The current register shall contain an elapsed time indication, indicating how many seconds of the interval have been processed (so far). The elapsed time attribute shall be initialized to zero at the start of the current interval. The current register elapsed time shall be able to indicate at least the elapsed time of the nominal interval; i.e., 86'400 s. When the maximum value of an elapsed time register is reached, the register shall remain at that maximum value until it is reset, or transferred. + +**Current register suspect interval flag:** The current register suspect interval flag will be set to "true" to indicate that the data stored in the register may not be reliable. The suspect interval flag shall be initialized to "true" for the very first interval of the measurement. The suspect interval flag shall be + +initialized to "false" at the start of subsequent new 24-hour intervals. During the 24-hour interval period, the suspect flag shall be set when the current register counter value is reset to zero (see also "End of accumulation period"). + +**Report current register:** It shall be possible to report the value of the current register when requested. + +**End of accumulation period:** At the end of the 24-hour accumulation period, the contents of the current register may be transferred to the recent register. Prior to the transfer, the suspect interval flag shall be set if the elapsed time deviates from more than 10 s of the nominal time, being 86 400 s. After the transfer, the current register shall be initialized. If the NE-RTC (and consequently the PMclock) is set to a time outside the current interval, the end of the 24-hour accumulation period shall be assumed, and the actions as specified above shall be performed. + +### 10.2.13 Current 24-hour snapshot register function – Cur24h-s + +**Symbol:** + +![Symbol diagram for Cur24h-s function. A central box labeled 'Cur24h-s' has two input arrows on the left: 'Gauges' and 'PMclock24h'. It has two output arrows on the right. The top output is labeled 'Current snapshot value' and 'Current suspect interval flag'. The bottom output is labeled 'End of 24 h period snapshot value' and 'End of 24 h period suspect interval flag'. A small text 'G.7710-Y.1701(20)-Amd.1(22)_F10-19' is at the bottom right.](070352b751dd0711b8ac6ddfa6df1d98_img.jpg) + +Symbol diagram for Cur24h-s function. A central box labeled 'Cur24h-s' has two input arrows on the left: 'Gauges' and 'PMclock24h'. It has two output arrows on the right. The top output is labeled 'Current snapshot value' and 'Current suspect interval flag'. The bottom output is labeled 'End of 24 h period snapshot value' and 'End of 24 h period suspect interval flag'. A small text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-19' is at the bottom right. + +**Figure 10-19 – Cur24h-s** + +**Interfaces:** + +**Table 10-15 – Cur24h-snapshot input and output signals** + +| Input(s) | Output(s) | +|----------------------|------------------------------------------------------------------------------------------------------------------------------------------| +| Gauges
PMclock24h | Current snapshot value
Current suspect interval flag
End of 24 h period snapshot value
End of 24 h period suspect interval flag | + +**Processes:** + +This function selects one gauge measurement as a current 24-hour snapshot. + +**Current register snapshot value:** The 24-hour current register shall hold the value of one gauge measurement. The gauge measurement shall be selected at a uniform time within the 24-hour interval. The current register's snapshot value shall not be initialized at the start of a new 24-hour interval; instead, it preserves the snapshot value from the previous 24-hour interval. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register suspect interval flag:** The current register suspect interval flag will be set to "true" to indicate that the data stored in the register may not be reliable. The suspect interval flag shall be initialized to "true" at the start of a 24-hour interval to indicate that no snapshot has yet been taken. The suspect interval flag shall be set to "false" after the snapshot has been taken. + +**Report current register:** It shall be possible to report the value of the current register when requested. + +**End of accumulation period:** At the end of the 24-hour accumulation period, the contents of the current register may be transferred to the recent register, after which the current register shall be initialized. If the NE-RTC (and consequently the PMclock) is set to a time outside the current interval, the end of the 24-hour accumulation period shall be assumed and the actions, as specified above, shall be performed. + +### 10.2.14 Current 24-hour tidemark register function – Cur24h-t + +**Symbol:** + +![Symbol diagram for Cur24h-t function. A central box labeled 'Cur24h-t' has two input arrows on the left: 'Gauges' from the top and 'PMclock24h' from the bottom. It has two output arrows on the right. The top output arrow points to three labels: 'Current high tidemark value', 'Current low tidemark value', and 'Current suspect interval flag'. The bottom output arrow points to three labels: 'End of 24 h period high tidemark value', 'End of 24 h period low tidemark value', and 'End of 24 h period suspect interval flag'. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-20'.](3750b0149a6380885998ab3ca6a8787c_img.jpg) + +Symbol diagram for Cur24h-t function. A central box labeled 'Cur24h-t' has two input arrows on the left: 'Gauges' from the top and 'PMclock24h' from the bottom. It has two output arrows on the right. The top output arrow points to three labels: 'Current high tidemark value', 'Current low tidemark value', and 'Current suspect interval flag'. The bottom output arrow points to three labels: 'End of 24 h period high tidemark value', 'End of 24 h period low tidemark value', and 'End of 24 h period suspect interval flag'. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-20'. + +**Figure 10-20 – Cur24h-t** + +**Interfaces:** + +**Table 10-16 – Cur24h-t input and output signals** + +| Input(s) | Output(s) | +|----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Gauges
PMclock24h | Current high tidemark value
Current low tidemark value
Current suspect interval flag
End of 24 h period high tidemark value
End of 24 h period low tidemark value
End of 24 h period suspect interval flag | + +**Processes:** + +This function registers the highest and lowest value of the periodic gauge measurements during the current 24-hour interval. + +**Current register high tidemark value:** The current 24-hour high tidemark register shall contain the maximum value achieved, so far, by the gauge during the 24-hour interval. The current register's high tidemark value shall be initialized to the instantaneous gauge value at the start of a new 24-hour interval. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register low tidemark value:** The current 24-hour low tidemark register shall contain the minimum value achieved, so far, by the gauge during the 24-hour interval. The current register's low tidemark value shall be initialized to the instantaneous gauge value at the start of a new 24-hour interval. Current data may be lost during failure conditions within the equipment and its power feeding. + +**Current register suspect interval flag:** The current register suspect interval flag will be set to "true" to indicate that the data stored in the register may not be reliable. The suspect interval flag shall be initialized to "false" at the start of a 24-hour interval. During the 24-hour interval period, the suspect flag shall be set when there is a lack of periodic gauge measurements. + +**Report current register:** It shall be possible to report the value of the current register when requested. + +**End of accumulation period:** At the end of the 24-hour accumulation period, the contents of the current register may be transferred to the recent register, after which the current register shall be initialized. If the NE-RTC (and consequently the PMclock) is set to a time outside the current interval, the end of the 24-hour accumulation period shall be assumed, and the actions as specified above shall be performed. + +### 10.2.15 Recent 24-hour register functions – Rec24h-c, Rec24h-s, Rec24h-t + +**Symbol:** + +![Symbol diagram for Rec24h-c, Rec24h-s, Rec24h-t functions. A yellow rectangular block contains a white box labeled '24-hour recent'. Above the box is the text 'Recent 24-hour register' with a downward arrow pointing to the box. To the left of the box is an upward arrow labeled 'PMclock'. To the right of the box is an upward arrow labeled 'End of 24 h period register'. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-21'.](38d82ffe820e339811b396206f40a201_img.jpg) + +Symbol diagram for Rec24h-c, Rec24h-s, Rec24h-t functions. A yellow rectangular block contains a white box labeled '24-hour recent'. Above the box is the text 'Recent 24-hour register' with a downward arrow pointing to the box. To the left of the box is an upward arrow labeled 'PMclock'. To the right of the box is an upward arrow labeled 'End of 24 h period register'. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-21'. + +**Figure 10-21 – Rec24h-c, Rec24h-s, Rec24h-t** + +**Interfaces:** + +**Table 10-17 – Rec24h-c, Rec24h-s, Rec24h-t input and output signals** + +| Input(s) | Output(s) | +|----------------------------------------|----------------------| +| End of 24 h period register
PMclock | Recent 24 h register | + +**Functions/Processes:** + +The Rec24h-c function stores the end of 24-hour period counter value, elapsed time and suspect interval flag in the recent register. The Rec24h-s function stores the end of 24-hour period snapshot value and suspect interval flag in the recent register. The Rec24h-t function stores the end of 24-hour period high tidemark value, low tidemark value and suspect interval flag in the recent register. + +**Recent register:** At the end of the 24-hour period, when history data storage is not suppressed, the current 24-hour register input shall be transferred to the recent register. Before the data is transferred, the data in the recent register shall be discarded. + +**Recent register time stamp:** The recent register shall contain a time-stamp indicating the end of the recent interval. + +**Report recent register:** It shall be possible to report the value of the recent registers when requested. + +### 10.2.16 Transient condition threshold function – ThrF-tr + +**Symbol:** + +![Symbol diagram for ThrF-tr function. A white rectangular block labeled 'ThrF-tr' has four input arrows from the left and bottom, and one output arrow to the right. The top input is labeled 'Threshold'. The left input is labeled 'Current count'. The bottom-left input is labeled 'PMclock'. The bottom input is labeled 'Reset'. The output arrow is labeled 'Threshold report'. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-22'.](d964618f772e53e0dcf684977e62daf9_img.jpg) + +Symbol diagram for ThrF-tr function. A white rectangular block labeled 'ThrF-tr' has four input arrows from the left and bottom, and one output arrow to the right. The top input is labeled 'Threshold'. The left input is labeled 'Current count'. The bottom-left input is labeled 'PMclock'. The bottom input is labeled 'Reset'. The output arrow is labeled 'Threshold report'. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-22'. + +**Figure 10-22 – ThrF-tr** + +##### **Interfaces:** + +**Table 10-18 – ThrF-tr input and output signals** + +| Input(s) | Output(s) | +|------------------------------------------------|------------------| +| Current count
Threshold
Reset
PMclock | Threshold report | + +##### **Processes:** + +The transient condition threshold function is used to generate an autonomous threshold report (TR) when the performance of a transport entity falls outside a predetermined level. This function is applicable for 15-minute and 24-hour intervals (refer to clause 10.1.7.3.2). + +The transient condition threshold function shall operate as specified in Figure 10-23. Every second, the current count shall be compared with the threshold. A threshold report (TR) shall be sent when the current count is equal to, or larger than, the threshold. When the current count is reset to zero, a TR shall be sent again in the current interval if the count reaches or exceeds the threshold. When the threshold is modified to a value lower than the current count, another TR shall be sent immediately. + +A threshold can be crossed at any second within the current interval. The function shall detect a 15-minute threshold crossing within 1 minute of its occurrence, and a 24-hour threshold crossing within 15 minutes of its occurrence. The 15-minute threshold report shall indicate the PM-second of the occurrence. The 24-hour threshold report shall indicate the moment of threshold crossing detection (that might be up to 15 minutes after the occurrence). The time-stamp shall have a resolution of 1 second. + +![Flowchart of the Transient condition threshold function. The process starts with 'ThrF-tr hunting', leading to 'New threshold' and '1 s'. 'New threshold' leads to 'Threshold = New threshold'. '1 s' leads to 'Read current count'. Both lead to a decision 'Current count ≥ threshold'. If 'N', it loops back to 'ThrF-tr hunting'. If 'Y', it goes to 'Threshold report', then 'ThrF-tr reported'. From 'ThrF-tr reported', it branches to 'New threshold', 'Period end', and 'Reset'. 'New threshold' leads to 'Threshold = New threshold', which leads to a decision 'Current count < threshold'. If 'Y', it goes to 'Period end'. If 'N', it loops back to 'ThrF-tr hunting'. 'Period end' and 'Reset' both lead to 'Period end'.](7b7596fb5ef925025341a9aacb6f2be7_img.jpg) + +``` + +graph TD + Start([ThrF-tr hunting]) --> NT1[/New threshold/] + Start --> S[/1 s/] + NT1 --> T1[Threshold = New threshold] + S --> RC[Read current count] + T1 --> CC1{Current count ≥ threshold} + RC --> CC1 + CC1 -- N --> Start + CC1 -- Y --> TR[/Threshold report/] + TR --> Start2([ThrF-tr reported]) + Start2 --> NT2[/New threshold/] + Start2 --> PE[/Period end/] + Start2 --> R[/Reset/] + NT2 --> T2[Threshold = New threshold] + T2 --> CC2{Current count < threshold} + CC2 -- Y --> PE + CC2 -- N --> Start + PE --> PE + R --> PE + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F10-23 + +Flowchart of the Transient condition threshold function. The process starts with 'ThrF-tr hunting', leading to 'New threshold' and '1 s'. 'New threshold' leads to 'Threshold = New threshold'. '1 s' leads to 'Read current count'. Both lead to a decision 'Current count ≥ threshold'. If 'N', it loops back to 'ThrF-tr hunting'. If 'Y', it goes to 'Threshold report', then 'ThrF-tr reported'. From 'ThrF-tr reported', it branches to 'New threshold', 'Period end', and 'Reset'. 'New threshold' leads to 'Threshold = New threshold', which leads to a decision 'Current count < threshold'. If 'Y', it goes to 'Period end'. If 'N', it loops back to 'ThrF-tr hunting'. 'Period end' and 'Reset' both lead to 'Period end'. + +**Figure 10-23 – Transient condition threshold function** + +### 10.2.17 Standing condition threshold function – ThrF-st + +**Symbol:** + +![Symbol diagram for ThrF-st function. A central box labeled 'ThrF-st' has inputs on the left: 'UAT', 'Current value', and 'Threshold' (top). It has a 'Reset threshold' input (top right) and two clock inputs, 'PMclock' and 'PMclock15m' (bottom). It has two outputs on the right: 'Threshold report' (top) and 'Reset threshold report' (bottom). A reference code 'G.7710-Y.1701(20)-Amd.1(22)_F10-24' is shown below the box.](b3d488012fdceacab867cf24c5efef05_img.jpg) + +Symbol diagram for ThrF-st function. A central box labeled 'ThrF-st' has inputs on the left: 'UAT', 'Current value', and 'Threshold' (top). It has a 'Reset threshold' input (top right) and two clock inputs, 'PMclock' and 'PMclock15m' (bottom). It has two outputs on the right: 'Threshold report' (top) and 'Reset threshold report' (bottom). A reference code 'G.7710-Y.1701(20)-Amd.1(22)\_F10-24' is shown below the box. + +**Figure 10-24 – ThrF-st** + +**Interfaces:** + +**Table 10-19 – ThrF-st input and output signals** + +| Input(s) | Output(s) | +|-------------------------------------------------------------------------------|--------------------------------------------| +| Current value
UAT
Threshold
Reset threshold
PMclock
PMclock15m | Threshold report
Reset threshold report | + +**Processes:** + +The standing condition threshold function is an option for 15-minute periods. The standing condition is raised, and a TR is generated when the threshold is reached or crossed. The standing condition is cleared, and a reset threshold report (RTR) is generated when, at the end of the period, the current count is below, or equal to, the reset threshold, provided that there was no unavailable time during that period (refer to clause 10.1.7.3.2). + +The standing condition threshold function shall operate as specified in Figure 10-25. When the standing condition is cleared, it shall be set to raised if the (changed) current counter value is equal to, or larger than, the (changed) threshold value. When the standing condition is raised, it shall be set to cleared at the end of a (following) 15-minute period if the current counter value is equal to, or lower than, the reset threshold value, provided that there is no unavailable time in the period. A threshold report (TR) shall be generated when the standing condition changes from cleared to raised. A reset threshold report (RTR) shall be generated when the standing condition changes from raised to cleared. + +NOTE – The behaviour on a change of the threshold value is compliant with [ITU-T M.2120], but not compliant with [ITU-T Q.822]. The latter requires generating an RTR when the threshold is modified to a value larger than the current register value. + +![Flowchart of the Standing condition threshold function. The process starts with 'ThrF-st cleared', leading to three parallel inputs: 'New reset threshold', 'New threshold', and '1 s'. These lead to 'Reset threshold = New reset threshold', 'Threshold = New threshold', and 'Read current count' respectively. A decision diamond 'Current count ≥ threshold' follows. If 'N' (No), it loops back to the start. If 'Y' (Yes), it leads to 'Threshold report', then 'ThrF-st raised'. From 'ThrF-st raised', three parallel inputs lead to 'New reset threshold', 'New threshold', and 'Period end'. These lead to 'Reset threshold = New reset threshold', 'Threshold = New threshold', and a decision diamond 'UAT in period'. If 'UAT in period' is 'Y', it loops back to the start. If 'N', it leads to a decision diamond 'Current count ≤ reset threshold'. If 'N', it loops back to the start. If 'Y', it leads to 'Reset threshold report', which then loops back to the start. A small text 'G.7710-Y.1701(20)-Amd.1(22)_F10-25' is at the bottom right.](ca86f53f9735fe98b6c6003d1b759f64_img.jpg) + +``` + +graph TD + Start1([ThrF-st cleared]) --> In1[/New reset threshold/] + Start1 --> In2[/New threshold/] + Start1 --> In3[/1 s/] + In1 --> Res1[Reset threshold = New reset threshold] + In2 --> Res2[Threshold = New threshold] + In3 --> Res3[Read current count] + Res1 --> Dec1{Current count ≥ threshold} + Res2 --> Dec1 + Res3 --> Dec1 + Dec1 -- N --> Start1 + Dec1 -- Y --> Out1{{Threshold report}} + Out1 --> Start2([ThrF-st raised]) + Start2 --> In4[/New reset threshold/] + Start2 --> In5[/New threshold/] + Start2 --> In6[/Period end/] + In4 --> Res4[Reset threshold = New reset threshold] + In5 --> Res5[Threshold = New threshold] + In6 --> Dec2{UAT in period} + Res4 --> Dec2 + Res5 --> Dec2 + Dec2 -- Y --> Start1 + Dec2 -- N --> Dec3{Current count ≤ reset threshold} + Dec3 -- N --> Start1 + Dec3 -- Y --> Out2{{Reset threshold report}} + Out2 --> Start1 + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F10-25 + +Flowchart of the Standing condition threshold function. The process starts with 'ThrF-st cleared', leading to three parallel inputs: 'New reset threshold', 'New threshold', and '1 s'. These lead to 'Reset threshold = New reset threshold', 'Threshold = New threshold', and 'Read current count' respectively. A decision diamond 'Current count ≥ threshold' follows. If 'N' (No), it loops back to the start. If 'Y' (Yes), it leads to 'Threshold report', then 'ThrF-st raised'. From 'ThrF-st raised', three parallel inputs lead to 'New reset threshold', 'New threshold', and 'Period end'. These lead to 'Reset threshold = New reset threshold', 'Threshold = New threshold', and a decision diamond 'UAT in period'. If 'UAT in period' is 'Y', it loops back to the start. If 'N', it leads to a decision diamond 'Current count ≤ reset threshold'. If 'N', it loops back to the start. If 'Y', it leads to 'Reset threshold report', which then loops back to the start. A small text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-25' is at the bottom right. + +**Figure 10-25 – Standing condition threshold function** + +A set threshold can be crossed at any second within the current interval. The function shall detect a 15-minute threshold crossing within 1 minute of its occurrence. The 15-minute TR and RTR shall indicate the PM-second of the occurrence. The time-stamp shall have a resolution of 1 second. + +### 10.2.18 Out of range function for gauge overflow detection – ORF-o + +Symbol: + +![Symbol diagram for ORF-o function. A central box labeled 'ORF-o' has three inputs: 'Gauge value' from the left, 'Threshold' from the top, and 'PMclock' from the bottom. It has one output: 'Out of range report' to the right. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-26'.](d9ea7e6c55ac790700d27c96ba7f66a3_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F10-26 + +Symbol diagram for ORF-o function. A central box labeled 'ORF-o' has three inputs: 'Gauge value' from the left, 'Threshold' from the top, and 'PMclock' from the bottom. It has one output: 'Out of range report' to the right. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-26'. + +Figure 10-26 – ORF-o + +Interfaces: + +Table 10-20 – ORF-o input and output signals + +| Input(s) | Output(s) | +|-------------------------------------|---------------------| +| Gauge value
Threshold
PMclock | Out of range report | + +Processes: + +The out of range function for gauge overflow detection is used to generate an autonomous out of range report (ORR) when the gauge value of a snapshot or high tidemark is at, or above, a predetermined level. This function is applicable for 15-minute and 24-hour intervals. + +The out of range function for gauge overflow detection shall operate as specified in Figure 10-27. Every time a new gauge value (snapshot or high tidemark) becomes available, the gauge value shall be compared with the threshold. An out of range report (ORR) shall be sent when the gauge is equal to or larger than the threshold. When the threshold is modified to a value lower than the current gauge value, another ORR shall be sent immediately. An ORR shall be sent again when, after resetting, the gauge becomes at or above the new threshold. + +![Flowchart of the Out of range function for gauge overflow detection. The process starts with 'ORF-o hunting', leading to 'New threshold' and 'New gauge value' (linked to 'Snapshot or high tidemark'). 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge ≥ threshold'. If 'N' (No), it loops back to 'ORF-o hunting'. If 'Y' (Yes), it leads to 'Out of range report', then 'ORF-o reported'. 'ORF-o reported' leads to 'New threshold' and 'Period end'. 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge < threshold'. If 'N' (No), it loops back to 'ORF-o reported'. If 'Y' (Yes), it loops back to 'ORF-o hunting'. A small note at the bottom right reads 'G.7710-Y.1701(20)-Amd.1(22)_F10-27'.](b3335932702b8668e62791e9fd12c9ff_img.jpg) + +``` + +graph TD + ORF_o_hunting([ORF-o hunting]) --> New_threshold_1[/New threshold/] + ORF_o_hunting --> New_gauge_value[/New gauge value/] + New_gauge_value -.-> Snapshot[Snapshot or high tidemark] + New_threshold_1 --> Threshold_1[Threshold = New threshold] + New_gauge_value --> Read_gauge[Read gauge] + Threshold_1 --> Gauge_ge_threshold{Gauge ≥ threshold} + Read_gauge --> Gauge_ge_threshold + Gauge_ge_threshold -- N --> ORF_o_hunting + Gauge_ge_threshold -- Y --> Out_of_range_report{{Out of range report}} + Out_of_range_report --> ORF_o_reported([ORF-o reported]) + ORF_o_reported --> New_threshold_2[/New threshold/] + ORF_o_reported --> Period_end[/Period end/] + New_threshold_2 --> Threshold_2[Threshold = New threshold] + Threshold_2 --> Gauge_lt_threshold{Gauge < threshold} + Gauge_lt_threshold -- N --> ORF_o_reported + Gauge_lt_threshold -- Y --> ORF_o_hunting + Period_end --> ORF_o_hunting + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F10-27 + +Flowchart of the Out of range function for gauge overflow detection. The process starts with 'ORF-o hunting', leading to 'New threshold' and 'New gauge value' (linked to 'Snapshot or high tidemark'). 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge ≥ threshold'. If 'N' (No), it loops back to 'ORF-o hunting'. If 'Y' (Yes), it leads to 'Out of range report', then 'ORF-o reported'. 'ORF-o reported' leads to 'New threshold' and 'Period end'. 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge < threshold'. If 'N' (No), it loops back to 'ORF-o reported'. If 'Y' (Yes), it loops back to 'ORF-o hunting'. A small note at the bottom right reads 'G.7710-Y.1701(20)-Amd.1(22)\_F10-27'. + +**Figure 10-27 – Out of range function for gauge overflow detection** + +A threshold can be crossed at any time within the current interval. The function shall detect a 15-minute threshold crossing within 1 minute of its occurrence, and a 24-hour threshold crossing within 15 minutes of its occurrence. The 15-minute and 24-hour ORR shall indicate the PM-second of the occurrence. The time-stamp shall have a resolution of 1 second. + +### 10.2.19 Out of range function for underflow detection – ORF-u + +Symbol: + +![Symbol diagram for ORF-u function. A central box labeled 'ORF-u' has three inputs: 'Gauge value' from the left, 'Threshold' from the top, and 'PMclock' from the bottom. It has one output: 'Out of range report' to the right. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)_F10-28'.](592f13acca3e6d5152dd4489f030d004_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_F10-28 + +Symbol diagram for ORF-u function. A central box labeled 'ORF-u' has three inputs: 'Gauge value' from the left, 'Threshold' from the top, and 'PMclock' from the bottom. It has one output: 'Out of range report' to the right. Below the diagram is the text 'G.7710-Y.1701(20)-Amd.1(22)\_F10-28'. + +Figure 10-28 – ORF-u + +Interfaces: + +Table 10-21 – ORF-u input and output signals + +| Input(s) | Output(s) | +|-------------------------------------|---------------------| +| Gauge value
Threshold
PMclock | Out of range report | + +Processes: + +The out of range function for gauge underflow detection is used to generate an autonomous out of range report (ORR) when the gauge value of a snapshot or low tidemark is at, or below, a predetermined level. This function is applicable for 15-minute and 24-hour intervals. + +The out of range function for gauge underflow detection shall operate as specified in Figure 10-29. Every time a new gauge value (snapshot or low tidemark) becomes available, the gauge value shall be compared with the threshold. An out of range report (ORR) shall be sent when the gauge is equal to, or smaller, than the threshold. When the threshold is modified to a value higher than the current gauge value, another ORR shall be sent immediately. An ORR shall be sent again, after resetting, the gauge becomes at or below the new threshold. + +![Flowchart for Out of range function for gauge underflow detection. The process starts with 'ORF-u hunting', leading to 'New threshold' and 'New gauge value' (linked to 'Snapshot or low tidemark'). 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge ≤ threshold'. If 'N' (No), it loops back to 'ORF-u hunting'. If 'Y' (Yes), it leads to 'Out of range report', then 'ORF-u reported'. 'ORF-u reported' leads to 'New threshold' and 'Period end'. 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge > threshold'. If 'N' (No), it loops back to 'ORF-u reported'. If 'Y' (Yes), it loops back to 'ORF-u hunting'.](3481cde1adf61b0452dd6489dada6d6a_img.jpg) + +``` + +graph TD + ORF_u_hunting([ORF-u hunting]) --> NT1[/New threshold/] + ORF_u_hunting --> NGV[/New gauge value/] + NGV -.-> SLT[Snapshot or low tidemark] + NT1 --> T1[Threshold = New threshold] + T1 --> G1{Gauge ≤ threshold} + G1 -- N --> ORF_u_hunting + G1 -- Y --> ORR[/Out of range report/] + ORR --> ORF_u_reported([ORF-u reported]) + ORF_u_reported --> NT2[/New threshold/] + ORF_u_reported --> PE[/Period end/] + NT2 --> T2[Threshold = New threshold] + T2 --> G2{Gauge > threshold} + G2 -- N --> ORF_u_reported + G2 -- Y --> ORF_u_hunting + +``` + +G.7710-Y.1701(20)-Amd.1(22)\_F10-29 + +Flowchart for Out of range function for gauge underflow detection. The process starts with 'ORF-u hunting', leading to 'New threshold' and 'New gauge value' (linked to 'Snapshot or low tidemark'). 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge ≤ threshold'. If 'N' (No), it loops back to 'ORF-u hunting'. If 'Y' (Yes), it leads to 'Out of range report', then 'ORF-u reported'. 'ORF-u reported' leads to 'New threshold' and 'Period end'. 'New threshold' leads to 'Threshold = New threshold', which then leads to a decision 'Gauge > threshold'. If 'N' (No), it loops back to 'ORF-u reported'. If 'Y' (Yes), it loops back to 'ORF-u hunting'. + +**Figure 10-29 – Out of range function for gauge underflow detection** + +A threshold can be crossed at any time within the current interval. The function shall detect a 15-minute threshold crossing within 1 minute of its occurrence, and a 24-hour threshold crossing within 15 minutes of its occurrence. The 15-minute and 24-hour ORR shall indicate the PM-second of the occurrence. The timestamp shall have a resolution of 1 second. + +### 10.2.20 Streamed performance data filtering function – SPDF + +Symbol: + +![Symbol diagram for SPDF function. A central box labeled 'SPDF' has three input arrows from the left, top, and bottom, and one output arrow to the right. The left input is labeled 'P_XXX'. The top input is labeled 'Subscription'. The bottom input is labeled 'PMclock'. The right output is labeled 'Subscribed P_XXX (t)'. The text 'G.7710(25)' is located to the right of the output arrow.](140bd031d724324269168296afd1e04d_img.jpg) + +Symbol diagram for SPDF function. A central box labeled 'SPDF' has three input arrows from the left, top, and bottom, and one output arrow to the right. The left input is labeled 'P\_XXX'. The top input is labeled 'Subscription'. The bottom input is labeled 'PMclock'. The right output is labeled 'Subscribed P\_XXX (t)'. The text 'G.7710(25)' is located to the right of the output arrow. + +Figure 10-30 – SPDF + +Interfaces: + +Table 10-22 – SPDF input and output signals + +| Input(s) | Output(s) | +|----------------------------------|----------------------| +| Subscription
P_XXX
PMclock | Subscribed P_XXX (t) | + +Processes: + +This function could filter the performance data based on the *subscription* from the MC system. It can also compact or format the requested performance data to reduce the volume of the data without any impact on the analysis on the MC system. + +The input P\_XXX represents all collected PM data, including the raw performance data from atomic functions, the processed and filtered performance data within the EMF (such as ES/SES and UAT), as well as data from non-atomic functions. The sampling interval for the performance MI parameters from the atomic function is one second and for the performance parameters from the non-atomic functions is implementation specific. + +The output is the subscribed performance data with timestamp which could be streamed to the MC system based on the reporting interval in the subscription. + +# 11 Security management + +See security requirements in [ITU-T M.3016.x]. + +See human user authentication requirements in clause A.1.4 of [ITU-T X.811]. + +See integrity provision through detection and acknowledgement requirements in clause 8.3 of [ITU-T X.815]. + +See data leakage prevention requirements in clause 8.12 of [ISO/IEC 27002]. + +See monitoring activities requirements in clause 8.16 of [ISO/IEC 27002]. + +# 12 Control plane management + +The clause describes the requirements for managing the control functions that are resided in the network element. + +## 12.1 Fault reporting management + +Fault reporting management (FRM) provides a function to notify the management/control system about the fault events of the transport element. A typical use case of FRM is the controller-based restoration that is one of the connection availability enhancement techniques in [ITU-T G.7702] for transport networks controlled by SDN controllers. It requires that transport equipment notifies fault events to the SDN controller immediately when the fault events occur in order to minimize interrupted service time. The FRM function processes fault events received from the transport plane atomic functions and report them to the SDN controller. It has internal functions that network operators can program their own types of fault events used to trigger the controller-based restoration. Figure 12-1 is a functional model of the FRM that consists of three functional blocks: fault event registration, fault event filtering, and fault event reporting. + +![Figure 12-1 – FRM functional diagram. The diagram shows the flow of fault information through three main blocks: Fault event registration, Fault event filtering, and Fault event reporting. An 'Atomic function' on the left provides 'cZZZ-value (fault cause)' to the registration block. The registration block outputs 'frmZZZ-value' to the filtering block. The filtering block outputs 'frmZZZ-value' and 'frmZZZ-fef' to the reporting block. The reporting block sends 'Query/report' and 'Notification' to 'Management applications function' on the right. A 'FEF information' block is shown above the filtering and reporting blocks, with an arrow pointing from it to the filtering block. Below the main FRM blocks, a 'Date and time functions' block is connected via a double-headed arrow labeled 'NE-RTC'.](56a42b3c4e1a79a71c8f27aa03b78b84_img.jpg) + +``` +graph LR + subgraph FRM [Fault reporting management] + direction LR + R[Fault event registration] -- frmZZZ-value --> F[Fault event filtering] + F -- frmZZZ-value, frmZZZ-fef --> Rep[Fault event reporting] + FEF[FEF information] --> F + end + AF[Atomic function] -- "cZZZ-value (fault cause)" --> R + Rep -- "Query/report, Notification" --> MA[Management applications function] + DTF[Date and time functions] <--> |NE-RTC| FRM +``` + +Figure 12-1 – FRM functional diagram. The diagram shows the flow of fault information through three main blocks: Fault event registration, Fault event filtering, and Fault event reporting. An 'Atomic function' on the left provides 'cZZZ-value (fault cause)' to the registration block. The registration block outputs 'frmZZZ-value' to the filtering block. The filtering block outputs 'frmZZZ-value' and 'frmZZZ-fef' to the reporting block. The reporting block sends 'Query/report' and 'Notification' to 'Management applications function' on the right. A 'FEF information' block is shown above the filtering and reporting blocks, with an arrow pointing from it to the filtering block. Below the main FRM blocks, a 'Date and time functions' block is connected via a double-headed arrow labeled 'NE-RTC'. + +G.7710-Y.1701(20)-Amd.1(22)\_F12-1 + +Figure 12-1 – FRM functional diagram + +### 12.1.1 Fault event registration + +The fault event registration function receives a fault event from the Atomic function, extracts information of the FRM fault required to trigger the controller-based restoration based on the incoming fault event and registers it with arrival timestamp. + +The fault event registration function is responsible for integration of fault causes MI\_cZZZ into FRM fault frmZZZ-value that includes identification of the managed entity and its location, an indication whether the fault has been raised or cleared, and a timestamp of this event. + +The FRM fault event declaration and clearing shall be time-stamped. For declaration, the timestamp shall indicate the time at which the fault cause is activated at the input of the fault event registration block. For clearing, the time-stamp shall indicate the time at which the fault cause is deactivated at the input of the fault event registration block. + +### 12.1.2 Fault event filtering + +Depending on the FRM configuration information received from the SDN controller, the fault event filtering (FEF) function decides whether incoming fault events shall be reported or not for the controller-based restoration. + +The FEF function is responsible for assigning a value to the frmZZZ-fef variable. The assignment shall be possible per managed entity and is based on the "FEF information". The "FEF information" sent from the SDN controller is used for classification to decide on which faults shall be reported for the controller-based restoration. + +The frmZZZ-fef value shall be "reported" when the "FEF information" specifies the probable cause to be "reported". The frmZZZ-fef value shall be "not reported" when the "FEF information" specifies + +the probable cause to be "not reported". The fault value accompanied with the assigned frmZZZ-fef shall become available at the output of the FEF function. + +Note that the FEF information includes the fault list that has been requested to be reported per managed entity. + +### **12.1.3 Fault event reporting** + +The fault event reporting function notifies to the SDN controller only the fault events identified as the reportable fault. It also stores all reportable fault events in order to synchronize the SDN controller. Upon query, the stored fault information shall be reported. + +# Appendix I + +## Overview of common and technology-specific ITU-T Recommendations + +(This appendix does not form an integral part of this Recommendation.) + +| | Generic | SDH | OTN (L1) | Ethernet transport | MPLS-TP | MTN | Media (L0) | Sync | +|--------------------------|-------------------------------------------|---------------------------------|---------------|-----------------------------------------|-----------------------------------------|--------------------------------------------|--------------------|--------------------------------------------------| +| Transport architecture | ITU-T G.800
ITU-T G.805
ITU-T G.807 | ITU-T G.803 | ITU-T G.872 | ITU-T G.8010 | ITU-T G.8110.1 | ITU-T G.8310 | ITU-T G.8310 | ITU-T G.826x (Freq)
ITU-T G.827x (Time/phase) | +| Interface | | | ITU-T G.709.x | ITU-T G.8013 | ITU-T G.8113.x | ITU-T G.8312 | ITU-T G.698.1-4 | | +| Equipment function | ITU-T G.806 | ITU-T G.783 | ITU-T G.798 | ITU-T G.8021 | ITU-T G.8121.x | ITU-T G.8321
ITU-T G.8331 | | | +| Mgmt/control requirement | ITU-T G.7710 | ITU-T G.784 | ITU-T G.874 | ITU-T G.8051 | ITU-T G.8151 | | | | +| Information model | ITU-T G.7711 | ITU-T G.774.1
-10
(CMISE) | ITU-T G.875 | ITU-T G.8052 | ITU-T G.8152 | ITU-T G.8350 | ITU-T G.876 | ITU-T G.7721 | +| Data model | | | | ITU-T G.8052.1
ITU-T G.8052.2 | ITU-T G.8152.1
ITU-T G.8152.2 | | | ITU-T G.7721.1 | + +G.7710-Y.1701(20)\_FI.1 + +Figure I.1 – Common and technology-specific ITU-T Recommendations + +# Appendix II + +## Protocol to set the local real-time clock within a few seconds relative to the external time reference + +(This appendix does not form an integral part of this Recommendation.) + +This mechanism assumes that the time for a message to be sent from the element management system (EMS) to the network element (NE) is not significantly different from that of the time it takes for the reply to return from the NE to the EMS. + +The mechanism also assumes that the message round trip time is meaningful in that the processing time within the NE is negligible, so a simple message that gets a small response shall be used. + +## II.1 Measure round trip time + +The round-trip time, $t$ , between sending a message and receiving the reply ( $T_2 - T_1$ in Figure II.1) is calculated a number of times. The mean and maximum difference (maximum time minus minimum time) for the round-trip time is determined. The messages that are used to determine the round-trip time are also used to request the NE's internal time ( $T_{NE}$ in Figure II.1), which is returned in the replies to the EMS. + +![Diagram illustrating the measurement of round trip time between an EMS and an NE. The EMS sends a 'Get time message' at time T1. The NE receives it at time T_NE and sends an 'NE time reply' back. The EMS receives the reply at time T2. The round trip time is labeled as t. A dashed line on the NE side indicates a time offset of 1/2 t.](c2f5e14ca0ed0f7944c7606451f67d85_img.jpg) + +The diagram shows two vertical lines representing the EMS and NE. On the EMS side, a point $T_1$ is marked on the vertical axis. An arrow labeled 'Get time message' points from $T_1$ to a point $T_{NE}$ on the NE's vertical axis. From $T_{NE}$ , an arrow labeled 'NE time reply' points back to a point $T_2$ on the EMS's vertical axis. A vertical dashed line on the EMS side between $T_1$ and $T_2$ is labeled 'Round trip time $t$ '. On the NE side, a vertical dashed line from $T_{NE}$ downwards is labeled $\frac{1}{2} t$ . At the bottom right, there is a small label: G.7710-Y.1701 (12)\_FII.1 + +Diagram illustrating the measurement of round trip time between an EMS and an NE. The EMS sends a 'Get time message' at time T1. The NE receives it at time T\_NE and sends an 'NE time reply' back. The EMS receives the reply at time T2. The round trip time is labeled as t. A dashed line on the NE side indicates a time offset of 1/2 t. + +Figure II.1 – Round trip time + +The mean round trip time is used to validate whether the traffic on the network is low, i.e., there are currently no significant delays being experienced by a message being sent to this NE. The maximum difference in message round trip times is used as a measure of the stability of the path between the EMS and NE across the network, i.e., constant and not varying due to fluctuations of traffic on the network. + +If the mean and maximum are within the required boundaries, the time drift between the EMS and NE clocks is calculated. + +## II.2 Calculate the time drift + +The time drift is the difference in time between the EMS clock and the NE clock. The time drift is calculated with the formula: + +$$\text{time drift} = T_2 - (T_{NE} + \frac{1}{2} t)$$ + +which can easily be validated from Figure II.1 above. When the time drift exceeds the synchronization requirement, the NE clock needs to be set. + +## II.3 Set NE clock + +To set the NE clock, the EMS sends the set time message containing the momentary EMS time ( $T_3$ in Figure II.2) plus an offset. This offset is equal to half the mean value of the round-trip time. + +![Sequence diagram showing the 'Set time message' being sent from EMS to NE. The EMS side starts at time T3, and the NE side receives it at time T3 + 1/2 t_mean.](238754529581b74f0696943d436494bb_img.jpg) + +``` + + sequenceDiagram + participant EMS + participant NE + Note left of EMS: T3 + EMS->>NE: Set time message + Note right of NE: T3 + 1/2 t_mean + +``` + +The diagram illustrates a message flow between two vertical axes representing the EMS and the NE. A downward-sloping arrow labeled "Set time message" originates from a point on the EMS axis marked $T_3$ and terminates at a point on the NE axis marked $T_3 + \frac{1}{2} t_{mean}$ . Below the NE axis is the identifier G.7710-Y.1701(12)\_FII.2. + +Sequence diagram showing the 'Set time message' being sent from EMS to NE. The EMS side starts at time T3, and the NE side receives it at time T3 + 1/2 t\_mean. + +**Figure II.2 – Set NE clock** + +Upon receipt of the set time message, the NE sets its clock to the time indicated in the message. + +# Appendix III + +# SDH and PDH Implementations of termination point mode and port mode + +(This appendix does not form an integral part of this Recommendation.) + +It must be noted that for SDH and PDH implementations there are several ways to suppress alarms (see Figure III.1). The trail termination point mode (TPmode) and port mode (Portmode), entering the defect correlation function, can be set to "Not Monitored" (NMON) to suppress the fault cause. The *ZZZ\_ Reported* indication, entering the defect correlation function, can be set to "Not Reported" to suppress the fault cause. These mechanisms, outlined in Figure 7-6 stop the information flow at the suppression point. Consequently, the alarm information does not become available at the management interface. + +NOTE – For new implementations (e.g., OTN equipment), this method has been replaced by the ARC method, defined in clause 7.2.1.3.2, because it can cause maintenance problems. + +![Flowchart of alarm reporting options in combination with previous alarm suppressing mechanisms. The process starts with 'Defects' entering a 'Defect correlation' block. This block has inputs: TPmode, Port Mode, ZZZ_ Reported, MON, and MON 'Reported'. It outputs 'Fault Cause' (cZZZ-value) to a 'Persistency' block. The 'Persistency' block outputs 'Failure' (fZZZ-value) to a 'Severity assignment' block. This block has a 'Severity' input and outputs 'Failure' (fZZZ-value, fZZZ-severity) to an 'Alarm reporting control' block. This block has an 'ARC info' input and outputs 'Alarm reporting, e.g., TMN alarm event notification' and 'Alarm information, e.g., current problem list'.](346324c08906e6d9320f632ab916f73e_img.jpg) + +SDH ITU-T G.783 + +``` +graph LR; Defects --> DC[Defect correlation]; DC -- "Fault Cause (cZZZ-value)" --> P[Persistency]; P -- "Failure (fZZZ-value)" --> SA[Severity assignment]; SA -- "Failure (fZZZ-value, fZZZ-severity)" --> ARC[Alarm reporting control]; ARC --> AR["Alarm reporting, e.g., TMN alarm event notification"]; ARC --> AI["Alarm information, e.g., current problem list"]; TPmode[TPmode] --> DC; PortMode[Port Mode] --> DC; ZZZ[ZZZ_ Reported] --> DC; MON1[MON] --> DC; MON2[MON 'Reported'] --> DC; Severity --> SA; ARCinfo[ARC info] --> ARC; +``` + +G.7710-Y.1701(20)-Amd.1(22)\_FIII.1 + +Flowchart of alarm reporting options in combination with previous alarm suppressing mechanisms. The process starts with 'Defects' entering a 'Defect correlation' block. This block has inputs: TPmode, Port Mode, ZZZ\_ Reported, MON, and MON 'Reported'. It outputs 'Fault Cause' (cZZZ-value) to a 'Persistency' block. The 'Persistency' block outputs 'Failure' (fZZZ-value) to a 'Severity assignment' block. This block has a 'Severity' input and outputs 'Failure' (fZZZ-value, fZZZ-severity) to an 'Alarm reporting control' block. This block has an 'ARC info' input and outputs 'Alarm reporting, e.g., TMN alarm event notification' and 'Alarm information, e.g., current problem list'. + +Figure III.1 – Report options in combination with previous alarm suppressing mechanisms + +For implementations supporting both the ARC and previous alarm suppression mechanisms, it is required to have specific values for the previous mechanisms in order to allow the ARC function to control the alarm reporting and information facilities. The specific value for the trail termination point mode and the port mode is "monitored" (MON), the specific value for *ZZZ\_ Reported* is "Reported". + +# Appendix IV + +# Administrative state examples + +(This appendix does not form an integral part of this Recommendation.) + +This appendix provides examples of applying the administrative states on a server layer trail and tandem connection monitoring (TCM). + +## IV.1 Lock a server layer trail + +Figure IV.1 shows a dual-sided locking of a server layer trail where the administrative locking is applied to the adaptation function at both edges of the server layer trail. The administrative locking is applied to the whole adaption functions. The requirements and behaviour of administrative locking described in clause 8.15 apply to both the source and sink directions of the adaptation function, as shown by the solid and dash lines of Client LCK signal flows in the figure. + +Single-sided locking of a server layer trail is also possible when the administrative locking is applied to the adaptation function only at one edge of the server layer trail. + +When the server layer trail is administrative locked, server layer path monitoring is still working. This allows the operator to validate that the server layer path is operational before unlocking the trail. + +![Diagram of a server layer trail showing dual-sided locking. Two clients are connected to server/client adaptation functions, which are connected to servers. The servers are connected via a server network connection. The trail is shown as a dashed line between the two server/client functions. LCK signals are shown flowing from the clients through the server/client functions and servers. The diagram is labeled with 'Client', 'Server/client', 'Server', 'Trail', 'Admin lock', 'LCK (in client CI)', 'Server network connection', and 'G.7710-Y.1701(20)-Amd.1(22)_FIV.1'.](23d9fcc2863a6b0548d6b4e8abf15106_img.jpg) + +The diagram illustrates a dual-sided locking configuration for a server layer trail. At the top, two ovals labeled 'Client' are shown. Each client is connected to a yellow trapezoidal block labeled 'Server/client'. An arrow labeled 'Admin lock' points to each of these blocks. Below each 'Server/client' block is a white trapezoidal block labeled 'Server'. A dashed line labeled 'Trail' connects the two 'Server/client' blocks. Below the 'Server' blocks, a dashed line labeled 'Server network connection' connects them. Green arrows labeled 'LCK' are shown flowing from the clients, through the 'Server/client' blocks, and down into the 'Server' blocks. Red dashed lines labeled 'LCK (in client CI)' are shown flowing from the 'Server' blocks back up through the 'Server/client' blocks to the clients. The diagram is labeled with 'G.7710-Y.1701(20)-Amd.1(22)\_FIV.1' at the bottom right. + +Diagram of a server layer trail showing dual-sided locking. Two clients are connected to server/client adaptation functions, which are connected to servers. The servers are connected via a server network connection. The trail is shown as a dashed line between the two server/client functions. LCK signals are shown flowing from the clients through the server/client functions and servers. The diagram is labeled with 'Client', 'Server/client', 'Server', 'Trail', 'Admin lock', 'LCK (in client CI)', 'Server network connection', and 'G.7710-Y.1701(20)-Amd.1(22)\_FIV.1'. + +Figure IV.1 – Locking a server layer trail + +## IV.2 Lock a tandem connection + +Figure IV.2 shows a dual-sided locking of a tandem connection where the administrative locking is applied to the adaptation function at both edges of the tandem connection. The administrative locking is applied to the whole adaption functions. The requirements and behaviour of administrative locking described in clause 8.15 apply to both the source and sink directions of the adaptation function, as shown by the solid and dash lines of Client LCK signal flows in the figure. + +Single-sided locking of a tandem connection is also possible when the administrative locking is applied to the adaptation function only at one edge of the tandem connection. + +When the tandem connection is administrative locked, TCM is still working. This allows the operator to validate that the tandem connection is operational before unlocking it. + +![Diagram illustrating the locking of a tandem connection between two TCM nodes. Each node consists of a yellow trapezoid on top of a white triangle labeled 'TCM'. Red arrows labeled 'LCK' point outwards from the yellow trapezoids. A dashed red line labeled 'LCK' connects the two yellow trapezoids. A dashed black line labeled 'Tandem connection' connects the two 'TCM' triangles. A label 'Admin lock' with arrows points to the yellow trapezoids. A small red arrow points upwards inside each yellow trapezoid. The diagram is labeled G.7710-Y.1701(20)-Amd.1(22)_FIV.2 at the bottom right.](c93c4b33a2b42c8dd6d82a354f2f89f1_img.jpg) + +G.7710-Y.1701(20)-Amd.1(22)\_FIV.2 + +Diagram illustrating the locking of a tandem connection between two TCM nodes. Each node consists of a yellow trapezoid on top of a white triangle labeled 'TCM'. Red arrows labeled 'LCK' point outwards from the yellow trapezoids. A dashed red line labeled 'LCK' connects the two yellow trapezoids. A dashed black line labeled 'Tandem connection' connects the two 'TCM' triangles. A label 'Admin lock' with arrows points to the yellow trapezoids. A small red arrow points upwards inside each yellow trapezoid. The diagram is labeled G.7710-Y.1701(20)-Amd.1(22)\_FIV.2 at the bottom right. + +**Figure IV.2 – Locking a tandem connection** + +# Bibliography + +- [b-ITU-T G.798] Recommendation ITU-T G.798 (2026), *Characteristics of optical transport network hierarchy equipment functional blocks - Overview*. +- [b-ITU-T G.874] Recommendation ITU-T G.874 (2020), *Management aspects of optical transport network elements*. +- [b-ITU-T G.7711] Recommendation ITU-T G.7711 (2025), *Generic protocol-neutral information model for transport resources*. +- [b-ITU-T G.8021] Recommendation ITU-T G.8021/Y.1341 (2022), *Characteristics of Ethernet transport network equipment functional blocks*. +- [b-ITU-T G.8051] Recommendation ITU-T G.8051 (2024), *Management aspects of the Ethernet transport (ET) capable network element*. +- [b-ITU-T G.8052] Recommendation ITU-T G.8052 (2024), *Protocol-neutral management information model for the Ethernet transport capable network element*. +- [b-ITU-T G.8121.x] Recommendation ITU-T G.8121/Y.1381 series, including [b-ITU-T G.8121], [b-ITU-T G.8121.1] and [b-ITU-T G.8121.2]. +- [b-ITU-T G.8121] Recommendation ITU-T G.8121/Y.1381 (2018), *Characteristics of MPLS-TP equipment functional blocks*. +- [b-ITU-T G.8121.1] Recommendation ITU-T G.8121.1/Y.1381.1 (2018), *Characteristics of MPLS-TP equipment functional blocks supporting ITU-T G.8113.1/Y.1372.1 OAM mechanisms*. +- [b-ITU-T G.8121.2] Recommendation ITU-T G.8121.2/Y.1381.2 (2018), *Characteristics of MPLS-TP equipment functional blocks supporting ITU-T G.8113.2/Y.1372.2 OAM mechanisms*. +- [b-ITU-T G.8151] Recommendation ITU-T G.8151 (2024), *Management aspects of the MPLS-TP network element*. +- [b-ANSI T1.231] ANSI Standard T1.231 (1997), *Digital Hierarchy – Layer 1 In-Service Digital Transmission Performance Monitoring*. +- [b-IETF RFC 1305] IETF RFC 1305 (1992), *Network Time Protocol (Version 3) Specification, Implementation and Analysis*. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git 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Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). + +Recommendation G.796 was prepared by Study Group XV and was approved under the Resolution No. 2 procedure on the 1st of September 1992. + +## --- CCITT NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized private operating agency. + +# **CHARACTERISTICS OF A 64 kbit/s CROSS-CONNECT EQUIPMENT WITH 2048 kbit/s ACCESS PORTS** + +(1992) + +## **Scope** + +This Recommendation gives the characteristics of a synchronous cross-connect equipment to be used in a synchronized digital network and which cross-connects time slots at 64 kbit/s or $n \times 64$ kbit/s from/to any 2048 kbit/s access port. + +## **1 General characteristics** + +### **1.1 Capacity** + +This parameter depends mainly on the network architecture. It can change with time. Increasing an equipment should not disturb the existing data traffic. + +### **1.2 Access ports** + +Access ports of a cross-connect equipment are input and output ports used to terminate 2048 kbit/s signals transporting synchronous 64 kbit/s and $n \times 64$ kbit/s signals to be cross-connected (see § 3). + +### **1.3 Timing signal** + +#### **1.3.1 Control of timing signal** + +It should be possible to derive the internal timing signal from the following: + +- a) one from a number of external source(s) at 2048 kHz; +- b) one from a number of 2048 kbit/s signal(s); +- c) from an internal oscillator. + +The frequency accuracy of signals in items a) and b) above will normally be $\pm 1 \times 10^{-11}$ . To take into account possible frequency deviations on these signals occurring due to failure in the synchronous network, the design of timing derivation circuits should assume a frequency accuracy of $\pm 1$ ppm. + +*Note* – The provision of timing signal outputs available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. + +#### **1.3.2 Timing performance** + +The timing performance of the internal clock should comply with Recommendation G.812. In the holdover mode, the local clock requirements of § 2.2.3 of Recommendation G.812 should be met. + +*Note* – For other timing performance options, refer to § 6.3 below. + +### **1.4 Blocking factor** + +For the mandatory functions in § 2.1 below, the blocking factor should be zero for cross-connect equipment of size up to 256 access ports of 2048 kbit/s; a zero blocking factor for the case of greater than 256 access ports is desirable. For the optional functions in § 2.2, the blocking factor should be as low as possible; the maximum value is under study. + +See Notes in §§ 2.1 and 2.2 below. + +## 2 Functions + +### 2.1 *Mandatory functions* + +- a) Cross-connection of 64 kbit/s and $n \times 64$ kbit/s signals, according to the TS order given in §§ 5.2 of Recommendation G.704 and 2.2.3 of Recommendation G.735, bidirectional. The equipment shall maintain octet sequence integrity of the signals being cross-connected; + +*Note 1* – The need to deal with $n \times 64$ kbit/s signals according to § 5.2 of Recommendation G.704 and $6 \times 64$ kbit/s (384 kbit/s) signals according to § 2.2.3 of Recommendation G.735, should be taken into account in the design of the equipment architecture to minimize any impact on delay and blocking factor. + +*Note 2* – For some $n \times 64$ kbit/s applications it is necessary to maintain octet sequence integrity within the same frame. + +- b) Management; These should include control functions and provision of maintenance information. + +### 2.2 *Optional functions* + +- a) Cross-connection of 64 kbit/s and $n \times 64$ kbit/s signals, unidirectional. The equipment shall maintain octet sequence integrity of the signals being cross-connected; + +*Note* – For some applications it is necessary to maintain octet sequence integrity within the same frame. + +- b) Cross-connection of channel associated signalling bits, a, b, c, d, in time slot 16 corresponding to the 64 kbit/s time slot cross-connection. The equipment shall maintain a, b, c, d bits integrity; +- c) Distribution of 64 and $n \times 64$ kbit/s signals on a broadcast basis; +- d) Cross-connection of $n \times 64$ kbit/s signals which are not according to the time slot order given in §§ 5.2 of Recommendation G.704 or 2.2.3 of Recommendation G.735 or those where the formats differ between input and output ports, bidirectional and unidirectional. The equipment shall maintain octet sequence integrity of the signals being cross-connected; + +*Note 1* – The need to deal with $n \times 64$ kbit/s signals with different formats should be taken into account in the design of the equipment architecture to minimize any impact on delay and blocking factor. + +*Note 2* – For some applications it is necessary to maintain octet sequence integrity within the same frame. + +- e) The following optional functions are under study: + - cross-connection of sub 64 kbit/s channels; + - cross-connection of 64 and $n \times 64$ kbit/s signals on a point-to-multipoint basis. + +## 3 Interfaces + +### 3.1 *2048 kbit/s interfaces* + +#### 3.1.1 *Physical interface* + +According to § 6 of Recommendation G.703. + +#### 3.1.2 *Frame structure* + +Refer to §§ 2.3 of Recommendation G.704 and 5 of Recommendation G.704 for basic frame structure and for characteristics of frame structure carrying channels at various bit rates in 2048 kbit/s. Bit 1 of the frame should be used in accordance with § 2.2.3 of Recommendation G.704, i.e. for a CRC check bit procedure. Refer to § 2.2.3 of Recommendation G.735 for time slot order of 384 kbit/s sound programme signals contained in a 2048 kbit/s frame. + +Depending on the application, some 2048 kbit/s access frames could contain channel associated or common channel signalling. + +### 3.2 *Synchronization interface at 2048 kHz* + +The physical and electrical characteristics of the synchronization interface shall be according to § 10 of Recommendation G.703. + +### 3.3 *Interface with TMN* + +Under study. + +### 3.4 *Local operator interface* + +According to Recommendation M.3010, F interface. + +## 4 **Frame alignment and CRC procedures** + +An illustration of the procedure is given in Figure 2/G.706. + +### 4.1 *Loss of frame alignment* + +Refer to § 4.1.1 of Recommendation G.706. + +### 4.2 *Recovery of frame alignment* + +Refer to § 4.1.2 of Recommendation G.706. + +### 4.3 *CRC multiframe alignment in time slot 0* + +Refer to § 4.2 of Recommendation G.706. + +### 4.4 *CRC bit monitoring* + +Refer to § 4.3 of Recommendation G.706. + +## 5 **Defect or failure conditions and performance monitoring** + +Figure 1/G.796 gives the location and definition of the reference points used in the specification of defect or failure conditions, performance monitoring and consequent actions. + +![Diagram of a reference model for a cross-connect. It shows two input lines on the left, labeled A1 and A2. A1 connects to a receiver symbol (a right-pointing triangle) which outputs to point B1. A2 connects to a transmitter symbol (a left-pointing triangle) which outputs to point B2. Both B1 and B2 connect to a cross-connection symbol (a square with an 'X'). The diagram is labeled T1511830-92 at the bottom right.](547f726730e589392f239257a833ede3_img.jpg) + +Diagram of a reference model for a cross-connect. It shows two input lines on the left, labeled A1 and A2. A1 connects to a receiver symbol (a right-pointing triangle) which outputs to point B1. A2 connects to a transmitter symbol (a left-pointing triangle) which outputs to point B2. Both B1 and B2 connect to a cross-connection symbol (a square with an 'X'). The diagram is labeled T1511830-92 at the bottom right. + +- A1 reference point G.704 frame logical signal at receiver part of 2048 kbit/s access port. +- A2 reference point G.704 frame logical signal at transmitter part of 2048 kbit/s access port. +- B1 reference point 64 kbit/s data channels derived from signals at A1 reference point before cross-connexion. +- B2 reference point 64 kbit/s data channels derived from signals at B1 reference point after cross-connection. + +- ▶ Receiver part of a 2048 kbit/s access port excluding the adaptation of the G.703 signal to the G.704 frame logical signal. +- ◀ Transmitter part of a 2048 kbit/s access port excluding the adaptation of the G.704 frame logical signal to the G.703 signal. +- ✕ Cross connection function. + +*Note* – A1 and A2 (respectively B1 and B2) are related to the same 2048 kbit/s access port. + +FIGURE 1/G.796 +**Reference model for a cross-connect** + +### 5.1 *Defect or failure conditions at the A1 reference point and consequent actions at the B1 and A2 reference points* + +#### 5.1.1 *Defect or failure conditions* + +The equipment should detect the following conditions: + +##### 5.1.1.1 *Failure of power supply* + +##### 5.1.1.2 *Loss of incoming signals at 2048 kbit/s* + +A loss of signal (LOS) defect condition is determined by the absence of signal transitions of either positive or negative polarity over a period of 255 contiguous pulse positions, starting with the last receipt of a pulse. + +A LOS defect condition is deemed to be terminated on the detection of an average pulse density of at least 12.5% over a period of 255 contiguous pulse positions starting with the receipt of a pulse. + +*Note 1* – The detection of this defect is required only when it does not result in an indication of loss of frame alignment. + +##### 5.1.1.3 *Loss of frame alignment* + +Refer to § 4.1 above. + +##### 5.1.1.4 *Loss of multiframe alignment* + +Refer to § 5.2 of Recommendation G.732. + +The detection of this defect is required when channel associated signalling is used. + +##### 5.1.1.5 *Error ratio $1 \times 10^{-3}$* + +Refer to § 4.1.5 of Recommendation G.736. + +*Note* – The detection of this defect is optional. When required, it could be determined by counting either the number of errored frame alignment words or the number of errored bits in frame alignment words or by using the CRC4 procedure. + +##### 5.1.1.6 *Reception of AIS* + +An AIS defect condition is determined when the incoming signal has less than two ZEROs in each of two consecutive diframe periods (512 bits per diframe). + +The defect is cleared if each of two consecutive frame periods contains three or more ZEROs or FAS has been found. + +##### 5.1.1.7 *Defect indication from a remote equipment* + +This is detected on bit 3 TS0 NFAS. + +##### 5.1.1.8 *Reception of AIS in time slot 16* + +Refer to § 4.2.4 of Recommendation G.736 and § 3.2.2 of Recommendation O.162. + +##### 5.1.1.9 *Other defect or failure conditions* + +E.g. frame slips: under study. + +#### 5.1.2 *Consequent actions* + +Further to the detection of a defect or a failure condition, appropriate consequent actions should be taken as specified in Table 1/G.796. The consequent actions should be taken rapidly as indicated below: + +- the application of AIS at B1 reference point should be taken within 3 ms of the detection of the relevant defect or failure condition; +- the maximum period between the detection of a defect or a failure condition and the transmission of a defect indication at the A2 reference point is a national requirement; a figure of the order of 100 ms is suggested; +- the maximum period between the detection of a defect or a failure condition and the generation of any failure information is dependent on the maintenance strategy for the equipment (see § 7). + +TABLE 1/G.796 + +##### **Defect or failure condition and consequent action for 2048 kbit/s access ports** + +| Defect or failure condition at the A1 reference point | Consequent actions | | | | +|-----------------------------------------------------------|----------------------------------------|----------------------------------------------------|-----------------------------------|--------------------| +| | Failure information generated (Note 1) | Defect indication to remote end A2 reference point | AIS applied at B1 reference point | | +| | | | Data TS | TS16 bits (Note 2) | +| Failure of power supply | | Yes (if practicable) | | | +| Loss of incoming signal | | Yes bit 3 TS0 NFAS | Yes | Yes | +| Loss of frame alignment | | Yes bit 3 TS0 NFAS | Yes | Yes | +| Error ratio $1 \times 10^{-3}$ (Note 5) | | Yes bit 3 TS0 NFAS | Yes (Note 3) | Yes (Note 3) | +| Defect indication received from remote end bit 3 TS0 NFAS | | No | No | No | +| AIS received | | Yes (Note 4) | Yes | Yes | +| Loss of multiframe alignment | | Yes bit 6 TS16 FR0 | No | Yes | +| Defect indication received from remote end bit 6 TS16 FR0 | | No | No | No | +| AIS received in TS16 | | Yes bit 6 TS16 FR0 | No | Yes | + +*Note 1* – For any particular failure condition, an action is initiated: + +- at the level of the equipment (e.g. bell, lamp, printer); or +- at the level of the management of the equipment, refer to § 7 below. + +Individually, it is possible to classify failure information as one of the following: + +- not applicable; +- maintenance event information (MEI); +- deferred maintenance alarm (DMA); +- prompt maintenance alarm (PMA). + +*Note 2* – Applicable if TS16 is used for channel associated signalling or channel associated supervision/maintenance. AIS is applied to the relevant a, b, c, d bits. + +*Note 3* – According to national requirements. + +*Note 4* – In order to enable appropriate actions at the remote end, the indication of reception of AIS should not be transmitted on bit 3 of TS0 NFAS. Transmission of this information is under study. + +*Note 5* – The detection of this defect condition is optional. + +### 5.2 *Defect or failure conditions and consequent actions for the core of the equipment* + +#### 5.2.1 *Defect or failure conditions* + +The equipment should detect the following conditions: + +##### 5.2.1.1 Failure of a connection + +A connection inside the equipment should be deemed to have failed when the 64 and $n \times 64$ kbit/s path between the A1 and A2 reference points of the relevant ports is not available for a period of time greater than 1 second. + +##### 5.2.1.2 Loss of synchronization signal(s) + +The equipment is timed on its own internal oscillator when that is not the normal mode of operation. + +##### 5.2.1.3 Other defect or failure conditions + +For further study. + +#### 5.2.2 Consequent actions + +Further to the detection of a defect or a failure condition, appropriate consequent actions should be taken as specified in Table 2/G.796. The consequent actions should be taken as soon as possible: + +- the application of AIS at relevant B2 reference points (or B1 or A2) should be taken within 3 ms of the detection of the defect or failure condition when this action is practicable; +- the maximum period between the detection of a defect or a failure condition and the transmission of defect indications to the remote end is a national requirement; a figure of the order of 100 ms is suggested; +- the maximum period between the detection of a defect or failure condition and the generation of any failure information is dependent on the maintenance strategy for the equipment. It is covered in § 7 below specifying the management aspects of cross-connect equipment. + +TABLE 2/G.796 + +##### **Defect or failure condition and consequent action for the core of the equipment** + +| Defect or failure | Consequent actions | | | | +|--------------------------------|----------------------------------------|----------------------------------------------------|-----------------------------------------------|--------------------| +| | Failure information generated (Note 1) | Defect indication to remote end A2 reference point | AIS applied at A2 or B1 or B2 reference point | | +| | | | Data TS | TS16 bits (Note 2) | +| Failure of a connection | | No | Yes (if practicable) | | +| Loss of synchronization signal | | Yes (Note 3) | No | No | + +Note 1 – See Note 1 of Table 1/G.796. + +Note 2 – See Note 2 of Table 1/G.796. + +Note 3 – This action should be taken at the level of all A2 reference points. In order to enable appropriate actions at the remote ends, the indication of loss of synchronization signal(s) should not be transmitted on bit 3 of TS0 NFAS. Transmission of this information is under study. + +### 5.3 Performance monitoring + +The following performance indications can be derived from error event and other fault conditions: + +- unavailable time; +- degraded performance; +- unacceptable performance. + +The strategy to determine these quality performance parameters are described in Recommendations M.20 and M.550. More details are given in § 7 below specifying management aspects of cross-connect equipment. + +## 6 Performance + +### 6.1 Jitter + +#### 6.1.1 Jitter at 2048 kbit/s output + +When the timing source is jitter free, the peak-to-peak jitter at any 2048 kbit/s output should not exceed 0.05 UI when it is measured in the range from $f_1 = 20$ Hz to $f_4 = 100$ kHz. + +#### 6.1.2 Jitter tolerance at 2048 kbit/s input + +The tolerance to jitter of any 2048 kbit/s input should be according to § 3 of Recommendation G.823. + +#### 6.1.3 Jitter transfer function + +The jitter transfer function between the input used for synchronization purposes and any 2048 kbit/s output should not exceed the gain/frequency limits given in Figure 2/G.796. The input signal shall be modulated with sinusoidal jitter. + +![Figure 2/G.796: Jitter transfer gain/frequency limits. The graph plots gain in dB (20 log Jout/Jin) against frequency. The limit starts at 0.5 dB from frequency f0 to 40 Hz. From 40 Hz to 400 Hz, it slopes down at 20 dB/decade. From 400 Hz to 100 kHz, it stays flat at -19.5 dB. Shaded regions indicate forbidden areas above the upper limit and below the lower limit.](64bacf564ff025df294b6d30341c76df_img.jpg) + +``` + +graph TD + A[f0, 0.5 dB] -- "(see Note 1)" --> B[40 Hz, 0.5 dB] + B -- "20 dB/decade" --> C[400 Hz, -19.5 dB] + C --> D[100 kHz, -19.5 dB] + +``` + +Figure 2/G.796: Jitter transfer gain/frequency limits. The graph plots gain in dB (20 log Jout/Jin) against frequency. The limit starts at 0.5 dB from frequency f0 to 40 Hz. From 40 Hz to 400 Hz, it slopes down at 20 dB/decade. From 400 Hz to 100 kHz, it stays flat at -19.5 dB. Shaded regions indicate forbidden areas above the upper limit and below the lower limit. + +$J_{out}$ Out signal jitter + $J_{in}$ In signal jitter + +Note 1 – The frequency $f_0$ should be less than 20 Hz and as low as possible (e.g. 10 Hz), taking into account the limitations of measuring equipment. + +Note 2 – To achieve accurate measurements, the use of a selective method is recommended with a bandwidth sufficiently small referred to the relevant measurement frequency but not wider than 40 Hz. + +FIGURE 2/G.796 + +##### Jitter transfer + +### 6.2 Transfer delay + +#### 6.2.1 64 and $n \times 64$ kbit/s signals + +The transfer delay of 64 and $n \times 64$ kbit/s signals through a cross-connect equipment should be as small as possible taking account of buffer sizes. The delay should not exceed 600 µs. + +#### 6.2.2 Channel associated signalling data in time slot 16 + +The transfer delay of channel associated signalling data in time slot 16 should not exceed 7 ms. + +### 6.3 *Slips* + +#### 6.3.1 *Operation without loss of synchronization* + +Two situations need to be considered: + +- i) the timing signal and the relevant input signal are timed from the same G.811 $1 \times 10^{-11}$ clock: no slips should occur assuming adequate wander buffers are provided; +- ii) the timing signal and the relevant input signal are timed from separate G.811 clocks: in this plesiochronous mode of operation, the rate of controlled slips should be in accordance with Recommendation G.822. + +#### 6.3.2 *Operation in case of loss of synchronization* + +##### 6.3.2.1 *Normal performance* + +The timing signal and the relevant input signal are independently timed as a result of loss of all synchronization signals: the rate of controlled slips should be limited to that caused by internal clock frequency changes in the holdover mode. Refer to § 1.3.2 above. + +##### 6.3.2.2 *More stringent performance* + +For the situation presented in § 6.3.2.1 above, the rate of controlled slips should be limited to that caused by internal clock frequency changes in the holdover mode assuming that the transit clock requirements of § 2.2.3 of Recommendation G.812 are met. + +##### 6.3.2.3 *Less stringent performance* + +For the situation presented in § 6.3.2.1 above, depending on the way the cross-connect equipment is synchronized, one of the following situations apply: + +- for the first 24 hours, no more than 10 controlled slips per hour (cross-connect equipment with only one external synchronization signal); +- for the first 24 hours, no more than 300 controlled slips per hour (cross-connect equipment with several independent external synchronization signals). + +### 6.4 *Error performance* + +The design objective long term error performance for a single pass through the equipment of a 64 kbit/s connection from/to reference points A1/A2 is: + +- no SES; +- better than 99.995% EFS (assuming Poisson distribution of errors). + +## 7 **Management** + +For further study. + +## 8 **Abbreviations** + +| | | +|------|-------------------------------------------------------------------| +| AIS | Alarm indication signal | +| CAS | Channel associated signalling | +| CRC | Cyclic redundancy check | +| CRC4 | Cyclic redundancy check 4 (applicable to 2048 kbit/s G.704 frame) | +| DMA | Deferred maintenance alarm | +| EFS | Error free second | + +| | | +|------|------------------------------------------------------------------------| +| FAS | Frame alignment signal | +| FR0 | Frame 0 (of a CAS signalling multiframe for a 2048 kbit/s G.704 frame) | +| LOS | Loss of signal | +| MEI | Maintenance event information | +| NFAS | Non-frame alignment signal | +| PMA | Prompt maintenance alarm | +| ppm | part per million | +| SES | Severely errored second | +| TMN | Telecommunications management network | +| TS | Time slot | +| TS0 | Time slot 0 (of a 2048 kbit/s G.704 frame) | +| TS16 | Time slot 16 (of a 2048 kbit/s G.704 frame) | +| UI | Unit interval | \ No newline at end of file diff --git a/marked/G/T-REC-G.8040-200509-I_PDF-E/raw.md b/marked/G/T-REC-G.8040-200509-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..2fbad7b39e6f4c4efa8e7953fc62aa84a4badd70 --- /dev/null +++ b/marked/G/T-REC-G.8040-200509-I_PDF-E/raw.md @@ -0,0 +1,364 @@ + + +**ITU-T** + +**G.8040/Y.1340** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(09/2005) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Ethernet over Transport aspects – General aspects + +SERIES Y: GLOBAL INFORMATION +INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS +AND NEXT-GENERATION NETWORKS + +Internet protocol aspects – Transport + +--- + +**GFP frame mapping into Plesiochronous Digital +Hierarchy (PDH)** + +ITU-T Recommendation G.8040/Y.1340 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| ETHERNET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| General aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Quality and availability targets | G.8200–G.8299 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.8040/Y.1340** + +# **GFP frame mapping into Plesiochronous Digital Hierarchy (PDH)** + +# **Summary** + +This Recommendation provides the mapping to be used for the transport of GFP frames over PDH at the various hierarchical bit rates defined in ITU-T Rec. G.702. This mapping covers the $N \times 1544$ kbit/s, $N \times 2048$ kbit/s, $N \times 44\,736$ kbit/s, and $N \times 34\,368$ kbit/s signals and is used in conjunction with the frame structures defined in ITU-T Recs G.704 and G.7043/Y.1343. + +###### **Source** + +ITU-T Recommendation G.8040/Y.1340 was approved on 6 September 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2006 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +###### Page + +| | | | +|-----|----------------------------------------------|---| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 1 | +| 4 | Abbreviations..... | 1 | +| 5 | Conventions ..... | 1 | +| 6 | Mapping GFP frames into PDH signals ..... | 2 | +| 6.1 | Mapping into $N \times 1544$ kbit/s ..... | 2 | +| 6.2 | Mapping into $N \times 2048$ kbit/s ..... | 2 | +| 6.3 | Mapping into $N \times 44\,736$ kbit/s ..... | 3 | +| 6.4 | Mapping into $N \times 34\,368$ kbit/s ..... | 4 | + +# Introduction + +The generic framing procedure (GFP), as defined in ITU-T Rec. G.7041/Y.1303, was developed for transport of data clients over synchronous digital hierarchy (SDH) networks of ITU-T Rec. G.707/Y.1322 and optical transport networks (OTN) of ITU-T Rec. G.709/Y.1331. Interfaces from the plesiochronous digital hierarchy (PDH) are ubiquitous, especially in the access networks where there is a desire to carry client data signals. GFP has been identified as a suitable technique for mapping data frames into PDH signals of the hierarchies of ITU-T Rec. G.704 as well as the virtually concatenated PDH signals as defined in ITU-T Rec. G.7043/Y.1343. + +## GFP frame mapping into Plesiochronous Digital Hierarchy (PDH) + +# 1 Scope + +This Recommendation provides the mapping of GFP-encapsulated data into PDH signals for transport over PDH trails. The octet-wise mapping into octet-oriented transport containers originally defined for GFP is maintained. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- ITU-T Recommendation G.702 (1988), *Digital hierarchy bit rates*. +- ITU-T Recommendation G.704 (1998), *Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels*. +- ITU-T Recommendation G.832 (1998), *Transport of SDH elements on PDH networks – Frame and multiplexing structures*. +- ITU-T Recommendation G.7041/Y.1303 (2005), *Generic framing procedure (GFP)*. +- ITU-T Recommendation G.7042/Y.1305 (2004), *Link capacity adjustment scheme (LCAS) for virtual concatenated signals*. +- ITU-T Recommendation G.7043/Y.1343 (2004), *Virtual concatenation of plesiochronous digital hierarchy (PDH) signals*. + +# 3 Definitions + +This Recommendation does not define any terms. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------|----------------------------------| +| GFP | Generic Framing Procedure | +| LCAS | Link Capacity Adjustment Scheme | +| PDH | Plesiochronous Digital Hierarchy | +| VCAT | Virtual Concatenation | + +# 5 Conventions + +The octets of the GFP frames are mapped into the PDH octets in transmission bit order. Specifically, bit 1 of a GFP octet is the first bit to be transmitted in the PDH octet into which it is mapped. + +# 6 Mapping GFP frames into PDH signals + +## 6.1 Mapping into $N \times 1544$ kbit/s + +### 6.1.1 Frame and multiframe format + +The 1544 kbit/s signal payload is typically arranged as 24 octets (i.e., time slots 1 to 24), as illustrated in Figure 6-1a. + +The multiframe structure for the 24-frame multiframe as described in ITU-T Rec. G.704 shall be used. The first octet following the first framing bit of the multiframe is used to carry the concatenation overhead, as defined in ITU-T Rec. G.7043/Y.1343 and illustrated in Figure 6-1b. This octet is reserved for all values of $N$ , ( $N = 1 \dots 16$ ). For the non-VCAT/LCAS case (which implies one 1544 kbit/s signal), the concatenation overhead octet shall be set to a value of 0x00. + +![Figure 6-1: Octet-aligned mapping for GFP into the 1544 kbit/s signal. Part (a) shows a single 1544 kbit/s frame structure with a framing bit 'F' and 24 octets (Octet #1 to Octet #24) over a 125 microsecond period. Part (b) shows the mapping of GFP frames into a 24-frame multiframe. The first octet of each frame is the concatenation overhead octet. GFP frame overhead is shown as a cross-hatched pattern. The diagram includes frame numbers 1 through 24, with vertical ellipses between frames 5 and 23. A legend indicates that cross-hatched boxes represent GFP frame overhead. The diagram is labeled G.8040/Y.1340_F6-1. cross-hatched box](c0e88e4bd3a209b66ee7cb67e1cec2be_img.jpg) + +125 $\mu$ s + +F Octet #1 Octet #2 ... Octet #24 + +a) 1544 kbit/s frame + +Concatenation overhead octet + +Frame number + +1 F +2 F +3 F +4 F +5 F +... +23 F +24 F + +G.8040/Y.1340\_F6-1 + +GFP frame overhead + +b) GFP mapping into the 24 frame 1544 kbit/s multiframe + +Figure 6-1: Octet-aligned mapping for GFP into the 1544 kbit/s signal. Part (a) shows a single 1544 kbit/s frame structure with a framing bit 'F' and 24 octets (Octet #1 to Octet #24) over a 125 microsecond period. Part (b) shows the mapping of GFP frames into a 24-frame multiframe. The first octet of each frame is the concatenation overhead octet. GFP frame overhead is shown as a cross-hatched pattern. The diagram includes frame numbers 1 through 24, with vertical ellipses between frames 5 and 23. A legend indicates that cross-hatched boxes represent GFP frame overhead. The diagram is labeled G.8040/Y.1340\_F6-1. cross-hatched box + +Figure 6-1/G.8040/Y.1340 – Octet-aligned mapping for GFP into the 1544 kbit/s signal + +### 6.1.2 GFP frame rate adaptation + +When neither GFP client data frames nor GFP client management frames are available from the GFP source adaptation process, GFP Idle frames shall be inserted in order to perform rate adaptation, filling the server capacity as described in ITU-T Rec. G.7041/Y.1303. + +### 6.1.3 Scrambling of the GFP payload + +GFP frames are scrambled consistent with ITU-T Rec. G.7041/Y.1303. + +### 6.1.4 GFP frame delineation + +GFP frame delineation is performed in the manner described in ITU-T Rec. G.7041/Y.1303. + +## 6.2 Mapping into $N \times 2048$ kbit/s + +### 6.2.1 Frame and multiframe format + +The basic frame structure at 2048 kbit/s as described in ITU-T Rec. G.704 shall be used. Time slots 1-31 are used to carry the GFP octets. + +The multiframe structure for the 16-frame multiframe as described in ITU-T Rec. G.704 shall be used. Time slot 1 of the first frame of the multiframe is used to carry the concatenation overhead, as defined in ITU-T Rec. G.7043/Y.1343 and illustrated in Figure 6-2. This octet is reserved for all + +values of $N$ , ( $N = 1 \dots 16$ ). For the non-VCAT/LCAS case (which implies one 2048 kbit/s signal), the concatenation overhead octet shall be set to a value of 0x00. + +![Figure 6-2/G.8040/Y.1340 – Octet-aligned mapping for GFP into the 2048 kbit/s signal. The diagram shows a 125µs time interval containing 16 frames. Each frame is labeled 'T.S.O' and contains a 'Concatenation overhead octet' (indicated by a diagonal hatched pattern) and 'GFP frame overhead' (indicated by a cross-hatched pattern). The frames are numbered 1 to 16, with vertical ellipses between frames 5 and 15. The diagram is labeled G.8040/Y.1340_F6-2.](acfc53eca625d62b38aa2563efa95c3e_img.jpg) + +Figure 6-2/G.8040/Y.1340 – Octet-aligned mapping for GFP into the 2048 kbit/s signal. The diagram shows a 125µs time interval containing 16 frames. Each frame is labeled 'T.S.O' and contains a 'Concatenation overhead octet' (indicated by a diagonal hatched pattern) and 'GFP frame overhead' (indicated by a cross-hatched pattern). The frames are numbered 1 to 16, with vertical ellipses between frames 5 and 15. The diagram is labeled G.8040/Y.1340\_F6-2. + +**Figure 6-2/G.8040/Y.1340 – Octet-aligned mapping for GFP into the 2048 kbit/s signal** + +### 6.2.2 GFP frame rate adaptation + +When neither GFP client data frames nor GFP client management frames are available from the GFP source adaptation process, GFP Idle frames shall be inserted in order to perform rate adaptation, filling the server capacity as described in ITU-T Rec. G.704/Y.1303. + +### 6.2.3 Scrambling of the GFP payload + +GFP frames are scrambled consistent with ITU-T Rec. G.704/Y.1303. + +### 6.2.4 GFP frame delineation + +GFP frame delineation is performed in the manner described in ITU-T Rec. G.704/Y.1303. + +## 6.3 Mapping into $N \times 44\,736$ kbit/s + +### 6.3.1 Frame format + +The multiframe format at 44 736 kbit/s, as described in ITU-T Rec. G.704, shall be used. As illustrated in Figure 6-3, each 44 736 kbit/s subframe (M-subframe) contains 672 bits, which may be regarded as 84 octets, with octets #11, #32, #53 and #74 straddling the F1, F2, F3, and F4 bits, respectively. The first octet (two nibbles) following the first framing bit (X1) of the multiframe is used to carry the concatenation overhead, as defined in ITU-T Rec. G.7043/Y.1343 and illustrated in Figure 6-4. This octet is reserved for all values of $N$ , ( $N = 1 \dots 8$ ). For the non-VCAT/LCAS case (which implies one 44 736 kbit/s signal), the concatenation overhead octet shall be set to a value of 0x00. + +![Figure 6-3/G.8040/Y.1340 – Octet structure for the 44 736 kbit/s signal subframe. The diagram shows a sequence of octets: X1, Octet #1, ..., Octet #11 (containing F1), ..., Octet #21, CII, Octet #22, ..., Octet #63, CI3, Octet #64, ..., Octet #74 (containing F4), ..., Octet #84. The diagram is labeled G.8040/Y.1340_F6-3.](2ba086df3506f81bae3a9b53725dcfea_img.jpg) + +Figure 6-3/G.8040/Y.1340 – Octet structure for the 44 736 kbit/s signal subframe. The diagram shows a sequence of octets: X1, Octet #1, ..., Octet #11 (containing F1), ..., Octet #21, CII, Octet #22, ..., Octet #63, CI3, Octet #64, ..., Octet #74 (containing F4), ..., Octet #84. The diagram is labeled G.8040/Y.1340\_F6-3. + +**Figure 6-3/G.8040/Y.1340 – Octet structure for the 44 736 kbit/s signal subframe** + +![Figure 6-4: GFP mapping into a 44 736 kbit/s signal frame. The diagram shows a 680 bit subframe structure with 7 subframe master-frames. It details the placement of Concatenation overhead octet and 84 bits, and identifies GFP frame overhead areas.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +The diagram illustrates the mapping of GFP frames into a 680-bit subframe. The subframe is divided into 7 subframe master-frames. The first octet is the Concatenation overhead octet. The remaining 679 bits are divided into 84 bits of payload and GFP frame overhead. The payload is further divided into 7 subframe master-frames, each containing 12 bits of payload and 12 bits of GFP frame overhead. The GFP frame overhead is indicated by a cross-hatch pattern. + +Figure 6-4: GFP mapping into a 44 736 kbit/s signal frame. The diagram shows a 680 bit subframe structure with 7 subframe master-frames. It details the placement of Concatenation overhead octet and 84 bits, and identifies GFP frame overhead areas. + +Figure 6-4/G.8040/Y.1340 – GFP mapping into a 44 736 kbit/s signal frame + +### 6.3.2 GFP frame rate adaptation + +When neither GFP client data frames nor GFP client management frames are available from the GFP source adaptation process, GFP Idle frames shall be inserted in order to perform rate adaptation, filling the server capacity as described in ITU-T Rec. G.7041/Y.1303. + +### 6.3.3 Scrambling of the GFP payload + +GFP frames are scrambled consistent with ITU-T Rec. G.7041/Y.1303. + +### 6.3.4 GFP frame delineation + +GFP frame delineation is performed in the manner described in ITU-T Rec. G.7041/Y.1303. + +## 6.4 Mapping into $N \times 34\ 368$ kbit/s + +### 6.4.1 Frame format + +The basic frame and multiframe structure at 34 368 kbit/s as described in ITU-T Rec. G.832 shall be used. As defined in ITU-T Rec. G.7043/Y.1343 and illustrated in Figure 6-5, the first octet following the FA2 octet of the multiframe is used to carry the concatenation overhead. This octet is reserved for all values of $N$ , ( $N = 1 \dots 8$ ). For the non-VCAT/LCAS case (which implies one 34 368 kbit/s signal), the concatenation overhead octet shall be set to a value of 0x00. + +![Figure 6-5: Octet-aligned mapping for GFP into the 34 368 kbit/s signal. The diagram shows a 59-column by 9-row frame structure. The first column contains FA1, FA2, and VLI. The second column contains the Concatenation overhead. The remaining columns contain GFP frame overhead, indicated by a cross-hatch pattern.](b10763be31553f31cbb795653b731a43_img.jpg) + +The diagram shows the octet-aligned mapping for GFP into the 34 368 kbit/s signal. The frame structure consists of 59 columns and 9 rows. The first column is divided into three octets: FA1, FA2, and VLI. The second column is the Concatenation overhead. The remaining columns (3 to 59) contain GFP frame overhead, which is indicated by a cross-hatch pattern. The GFP frame overhead is distributed across the 9 rows, with some rows containing more overhead than others. + +Figure 6-5: Octet-aligned mapping for GFP into the 34 368 kbit/s signal. The diagram shows a 59-column by 9-row frame structure. The first column contains FA1, FA2, and VLI. The second column contains the Concatenation overhead. The remaining columns contain GFP frame overhead, indicated by a cross-hatch pattern. + +Figure 6-5/G.8040/Y.1340 – Octet-aligned mapping for GFP into the 34 368 kbit/s signal + +### **6.4.2 GFP frame rate adaptation** + +When neither GFP client data frames nor GFP client management frames are available from the GFP source adaptation process, GFP Idle frames shall be inserted in order to perform rate adaptation, filling the server capacity as described in ITU-T Rec. G.7041/Y.1303. + +### **6.4.3 Scrambling of the GFP payload** + +GFP frames are scrambled consistent with ITU-T Rec. G.7041/Y.1303. + +### **6.4.4 GFP frame delineation** + +GFP frame delineation is performed in the manner described in ITU-T Rec. G.7041/Y.1303. + + + +# ITU-T Y-SERIES RECOMMENDATIONS + +## GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS + +## GLOBAL INFORMATION INFRASTRUCTURE + +| | | +|-------------------------------------------|-------------| +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | + +## INTERNET PROTOCOL ASPECTS + +| | | +|--------------------------------------------------------------------|----------------------| +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | + +## NEXT GENERATION NETWORKS + +| | | +|-------------------------------------------------------------------|---------------| +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Numbering, naming and addressing | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Network control architectures and protocols | Y.2500–Y.2599 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.811-199709-I_PDF-E/raw.md b/marked/G/T-REC-G.811-199709-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..509450c24f909cd26e4a087bb0660c397bacc5c1 --- /dev/null +++ b/marked/G/T-REC-G.811-199709-I_PDF-E/raw.md @@ -0,0 +1,283 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.811** + +(09/97) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – Design +objectives for digital networks + +# --- **Timing characteristics of primary reference clocks** + +ITU-T Recommendation G.811 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| General | G.700–G.709 | +| Coding of analogue signals by pulse code modulation | G.710–G.719 | +| Coding of analogue signals by methods other than PCM | G.720–G.729 | +| Principal characteristics of primary multiplex equipment | G.730–G.739 | +| Principal characteristics of second order multiplex equipment | G.740–G.749 | +| Principal characteristics of higher order multiplex equipment | G.750–G.759 | +| Principal characteristics of transcoder and digital multiplication equipment | G.760–G.769 | +| Operations, administration and maintenance features of transmission equipment | G.770–G.779 | +| Principal characteristics of multiplexing equipment for the synchronous digital hierarchy | G.780–G.789 | +| Other terminal equipment | G.790–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Telecommunications management network | G.850–G.859 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +# **ITU-T RECOMMENDATION G.811** + +# **TIMING CHARACTERISTICS OF PRIMARY REFERENCE CLOCKS** + +## **Summary** + +This Recommendation outlines minimum requirements for timing devices used as primary reference clocks in synchronization networks. These networks include Public Switched Telephone Networks (PSTNs) and Synchronous Digital Hierarchy (SDH) networks. + +### **Source** + +ITU-T Recommendation G.811 was revised by ITU-T Study Group 13 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 19th of September 1997. + +### **Keywords** + +Clock, Clock Performance Objectives, Clock Performance Parameters, Jitter Performance, Wander Performance. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +### NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had/had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1998 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | Page | +|-------------------------------------------------|-------------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions..... | 2 | +| 4 Abbreviations..... | 2 | +| 5 Frequency accuracy..... | 2 | +| 6 Noise generation ..... | 2 | +| 6.1 Wander ..... | 2 | +| 6.2 Jitter..... | 4 | +| 7 Phase discontinuity..... | 4 | +| 8 Degradation of the performance of a PRC ..... | 4 | +| 9 Interfaces..... | 4 | + + + +# **TIMING CHARACTERISTICS OF PRIMARY REFERENCE CLOCKS** + +*(revised in 1997)* + +## **1 Scope** + +This Recommendation outlines the requirements for Primary Reference Clocks (PRCs) suitable for synchronization supply to digital networks. These requirements apply under the normal environmental conditions specified for digital equipment. + +A typical PRC provides the reference signal for the timing or synchronization of other clocks within a network or section of a network. In particular, the PRC can also provide the reference signal to the slave clock specified in Recommendation G.812 within the network nodes where the PRC is located. This Recommendation defines the PRC output but it does not apply to the output of slave clock directly fed by a PRC. The long-term accuracy of the PRC should be maintained at 1 part in $10^{11}$ or better with verification to Coordinated Universal Time (UTC). A PRC may be realized as an autonomous clock, operating independently of other sources. Alternatively, the PRC may be realized as a non-autonomous clock which is disciplined by UTC-derived precision signals received from a radio or satellite system. In either case, the requirements for long-term accuracy and short-term stability, as specified in this Recommendation, apply. + +The long-term accuracy of 1 part in $10^{11}$ or better is adequate when a single PRC provides the reference synchronization signal to all other clocks within a network (synchronous mode of operation). In the pseudo-synchronous mode, i.e. not all clocks in the network have timing traceable to the same PRC, the long-term accuracy is dependent on the number of PRCs in that network. + +When more than one PRC is used in a network, a statistical approach is needed to determine the long-term accuracy of each PRC in that network. + +## **2 References** + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] CCITT Recommendation G.703 (1991), *Physical/electrical characteristics of hierarchical digital interfaces*. +- [2] ITU-T Recommendation G.783 (1997), *Characteristics of Synchronous Digital Hierarchy (SDH) equipment functional blocks*. +- [3] ITU-T Recommendation G.810 (1996), *Definitions and terminology for synchronization networks*. +- [4] CCITT Recommendation G.812 (1988), *Timing requirements at the outputs of slave clocks suitable for plesiochronous operation of international digital links*. +- [5] CCITT Recommendation G.822 (1988), *Controlled slip rate objectives on an international digital connection*. +- [6] ITU-T Recommendation G.823 (1993), *The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy*. +- [7] ITU-T Recommendation G.824 (1993), *The control of jitter and wander within digital networks which are based on the 1544 kbit/s hierarchy*. +- [8] ITU-T Recommendation G.825 (1993), *The control of jitter and wander within digital networks which are based on the Synchronous Digital Hierarchy (SDH)*. + +## 3 Definitions + +The terms and definitions used in this Recommendation are contained in Recommendation G.810. + +## 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------|-------------------------------------| +| CMI | Coded Mark Inversion | +| FPM | Flicker Phase Modulation | +| MTIE | Maximum Time Interval Error | +| NE | Network Element | +| OAM | Operations and Maintenance | +| PLL | Phase Locked Loop | +| PRC | Primary Reference Clock | +| SDH | Synchronous Digital Hierarchy | +| SEC | SDH Equipment Clock | +| SSMB | Synchronization Status Message Byte | +| STM | Synchronous Transport Module | +| TDEV | Time Deviation | +| UI | Unit Interval | +| UTC | Coordinated Universal Time | +| WFM | White Frequency Modulation | + +## 5 Frequency accuracy + +The maximum allowable fractional frequency offset for observation times greater than one week is 1 part in $10^{11}$ , over all applicable operational conditions. + +## 6 Noise generation + +The noise generation of a PRC clock represents the amount of phase noise produced at its output. A suitable reference, for practical testing purposes, implies a performance level that is more stable than the output requirements. The ability of the clock to limit this noise is described by its frequency stability. The measures MTIE and Time Deviation (TDEV) are useful for characterization of noise generation performance. + +MTIE and TDEV are measured through an equivalent 10 Hz, first-order, low-pass measurement filter, at a maximum sampling time $\tau_0$ of 1/30 seconds. The minimum measurement period for TDEV is twelve times the integration period ( $T = 12\tau$ ). For measurements over longer observation periods, alternative filter bandwidth and sampling time may be required for practical considerations. + +### 6.1 Wander + +The wander, expressed in MTIE, measured using the independent clock configuration defined in Figure 2a/G.810 should have the following limits: + +$$\begin{array}{llll} \text{MTIE:} & 0.275 \times 10^{-3}\tau + 0.025 \mu\text{s} & \text{for} & 0.1 < \tau \leq 1000 \text{ s} \\ & 10^{-5}\tau + 0.29 \mu\text{s} & \text{for} & \tau > 1000 \text{ s} \end{array}$$ + +The resultant requirements are shown in Figure 1. + +![Figure 1/G.811: MTIE as a function of an observation (integration) period τ. The graph is a log-log plot with the y-axis labeled 'MTIE micro-seconds' ranging from 0.01 to 1000, and the x-axis labeled 'Observation period (seconds)' ranging from 0.01 to 1E + 08. The curve starts at 0.02 micro-seconds for 0.01 seconds, remains flat until 1 second, then rises with a slope of 1/2 until 100 seconds (reaching 0.3 micro-seconds), then has a flat section until 1000 seconds (reaching 0.4 micro-seconds), then rises with a slope of 1/2 until 10000 seconds (reaching 1.2 micro-seconds), and finally rises with a slope of 1 until 1E + 06 seconds (reaching 1000 micro-seconds). A straight line with a slope of 1/2 is shown for comparison.](b93cbfb52e37619e688175a6aad9edd9_img.jpg) + +Figure 1/G.811: MTIE as a function of an observation (integration) period τ. The graph is a log-log plot with the y-axis labeled 'MTIE micro-seconds' ranging from 0.01 to 1000, and the x-axis labeled 'Observation period (seconds)' ranging from 0.01 to 1E + 08. The curve starts at 0.02 micro-seconds for 0.01 seconds, remains flat until 1 second, then rises with a slope of 1/2 until 100 seconds (reaching 0.3 micro-seconds), then has a flat section until 1000 seconds (reaching 0.4 micro-seconds), then rises with a slope of 1/2 until 10000 seconds (reaching 1.2 micro-seconds), and finally rises with a slope of 1 until 1E + 06 seconds (reaching 1000 micro-seconds). A straight line with a slope of 1/2 is shown for comparison. + +Figure 1/G.811 – MTIE as a function of an observation (integration) period $\tau$ + +The wander, expressed in TDEV, measured using the independent clock configuration defined in Figure 2a/G.810 should have the following limits: + +| | | | | +|--------------|----------------|-----|---------------------------| +| TDEV: | 3 ns | for | $0.1 < \tau \leq 100$ s | +| | $0.03 \tau$ ns | for | $100 < \tau \leq 1000$ s | +| | 30 ns | for | $1000 < \tau < 10\,000$ s | + +The resultant requirements are shown in Figure 2. + +![Figure 2/G.811: TDEV as a function of an observation (integration) period τ. The graph is a log-log plot with the y-axis labeled 'TDEV nano-seconds' ranging from 1 to 1000, and the x-axis labeled 'Observation period (seconds)' ranging from 0.1 to 10 000. The curve is horizontal at 3 nano-seconds from 0.1 to 100 seconds, then rises linearly with a slope of 1/2 until 1000 seconds (reaching 30 nano-seconds), and then remains horizontal at 30 nano-seconds until 10 000 seconds.](0f3e3ea50bcceb86f6c524ab2b6f3e7a_img.jpg) + +Figure 2/G.811: TDEV as a function of an observation (integration) period τ. The graph is a log-log plot with the y-axis labeled 'TDEV nano-seconds' ranging from 1 to 1000, and the x-axis labeled 'Observation period (seconds)' ranging from 0.1 to 10 000. The curve is horizontal at 3 nano-seconds from 0.1 to 100 seconds, then rises linearly with a slope of 1/2 until 1000 seconds (reaching 30 nano-seconds), and then remains horizontal at 30 nano-seconds until 10 000 seconds. + +Figure 2/G.811 – TDEV as a function of an observation (integration) period $\tau$ + +### 6.2 Jitter + +While most specifications in this Recommendation are independent of the output interface at which they are measured, this is not the case for jitter production; jitter generation specifications must utilize existing specifications that are currently specified differently for different interface rates. These requirements are stated separately for the interfaces identified in clause 8. To be consistent with other jitter requirements, the specifications are in UIpp, where the UI corresponds to the reciprocal of the bit rate of the interface. + +The intrinsic jitter at 2048 kHz and 2048 kbit/s output interfaces as measured over a 60-second interval shall not exceed 0.05 UIpp when measured through a single pole band-pass filter with corner frequencies at 20 Hz and 100 kHz. + +The intrinsic jitter at 1544 kbit/s output interfaces as measured over a 60-second interval shall not exceed 0.015 UIpp when measured through a single pole band-pass filter with corner frequencies at 10 Hz and 40 kHz. + +## 7 Phase discontinuity + +Primary reference clocks need a very high reliability and are likely to include replication of the equipment in order to ensure the continuity of the output. However, any phase discontinuity, due to internal operations within the clock, should only result in a lengthening or shortening of the timing signal interval and must not, at the clock output, cause a phase discontinuity in excess of 1/8 UI (this refers to output signals at 1544 kbit/s, 2048 kbit/s or 2048 kHz). + +## 8 Degradation of the performance of a PRC + +If redundancy is applied and a clock frequency departs significantly from its nominal value, this should be detected and switching to an undegraded oscillator should then be effected. This switching should be accomplished before the MTIE or TDEV specification is exceeded. + +## 9 Interfaces + +The requirements in this Recommendation are related to reference points which may be internal to the equipment or NE in which the PRC is embedded and are therefore not necessarily available for measurement or analysis by the user. Consequently, the performance of the PRC is not specified at these internal reference points, but rather at the external interfaces of the equipment. The output interfaces specified for the equipment in which the PRC clock may be contained are: + +- 2048 kHz interfaces according to clause 10/G.703 with additional jitter and wander requirements as specified herein; +- 1544 kbit/s interfaces according to clause 2/G.703 with additional jitter and wander requirements as specified herein; +- 2048 kbit/s interfaces according to clause 6/G.703 with additional jitter and wander requirements as specified herein; +- other interfaces (such as sine wave 8 kHz to 5 MHz) are for further study. + +Note that not all of the above interfaces may be implemented on all equipment. + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | 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quality and availability targets + +--- + +### **Timing characteristics of telecom boundary clocks and telecom time synchronous clocks for use with partial timing support from the network** + +![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **Transmission systems and media, digital systems and networks** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100-G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200-G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300-G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400-G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450-G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600-G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700-G.799 | +| DIGITAL NETWORKS | G.800-G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900-G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000-G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000-G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000-G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000-G.8999 | +| Ethernet over Transport aspects | G.8000-G.8099 | +| MPLS over Transport aspects | G.8100-G.8199 | +| Synchronization, quality and availability targets | G.8200-G.8299 | +| Mobile network transport aspects | G.8300-G.8399 | +| Service Management | G.8600-G.8699 | +| ACCESS NETWORKS | G.9000-G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.8273.4 + +# Timing characteristics of telecom boundary clocks and telecom time synchronous clocks for use with partial timing support from the network + +## Summary + +Recommendation ITU-T G.8273.4 specifies minimum requirements for time and phase synchronization equipment used in synchronization networks that operates in the assisted partial timing support (APTS) and partial timing support (PTS) architectures. + +## History \* + +| Edition | Recommendation | Approval | Study Group | Unique ID | +|---------|---------------------------------------|------------|-------------|--------------------| +| 1.0 | ITU-T G.8273.4/Y.1368.4 | 2020-03-15 | 15 | 11.1002/1000/14214 | +| 1.1 | ITU-T G.8273.4/Y.1368.4 (2020) Amd. 1 | 2021-05-29 | 15 | 11.1002/1000/14626 | +| 1.2 | ITU-T G.8273.4/Y.1368.4 (2020) Amd. 2 | 2022-11-13 | 15 | 11.1002/1000/15154 | +| 2.0 | ITU-T G.8273.4 | 2024-08-29 | 15 | 11.1002/1000/16094 | + +## Keywords + +Assisted partial time support, boundary clock, partial time support, phase synchronization, time synchronization. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2025 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|-----|------------------------------------------------------------------------------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Conventions ..... | 3 | +| 6 | Physical layer frequency performance requirements..... | 3 | +| 7 | Performance requirements for T-BC-A and T-TSC-A ..... | 4 | +| 7.1 | Frequency accuracy ..... | 4 | +| 7.2 | Time error noise generation..... | 4 | +| 7.3 | Noise tolerance ..... | 5 | +| 7.4 | Local time reference (1 PPS) to PTP and local time reference (1 PPS) to
1 PPS noise transfer..... | 5 | +| 7.5 | PTP output and 1 PPS output transient response (short term) due to loss
and restoration of local time reference (1 PPS) input..... | 6 | +| 7.6 | Holdover performance..... | 6 | +| 8 | Performance requirements for T-BC-P and T-TSC-P ..... | 8 | +| 8.1 | Frequency accuracy ..... | 8 | +| 8.2 | Time error noise generation..... | 8 | +| 8.3 | Noise tolerance ..... | 9 | +| 8.4 | Noise transfer..... | 9 | +| 8.5 | Transient response (short-term)..... | 9 | +| 8.6 | Holdover performance..... | 10 | +| 9 | Interfaces..... | 11 | +| 9.1 | Phase and time interfaces ..... | 12 | +| 9.2 | Frequency interfaces..... | 12 | +| | Annex A – T-TSC-A and T-BC-A functional model ..... | 13 | +| | Annex B – T-TSC-P and T-BC-P functional model ..... | 16 | +| | Appendix I – Consideration of timeReceiver clocks embedded in end applications..... | 19 | +| | Appendix II – Consideration of variable temperature testing..... | 20 | +| | Appendix III – Consideration of the use of a synchronous equipment clock to maintain
time holdover for partial timing support networks..... | 21 | +| | Appendix IV – Use of a synchronous equipment clock to assist a PTP time lock ..... | 22 | +| | Appendix V – Synchronization interworking function P-F node limits ..... | 23 | +| | Appendix VI – PTP noise tolerance testing for PTS and APTS clocks..... | 24 | +| | VI.1    Testing set-up for PTP noise tolerance testing ..... | 24 | + +| | Page | +|---------------------------------------------------------------------------------------------------|------| +| VI.2 Statistical PDV model ..... | 25 | +| VI.3 Parameters for the PDV model..... | 26 | +| VI.4 Different requirements for APTS and PTS models..... | 27 | +| VI.5 Example delay patterns..... | 28 | +| VI.6 Output requirements ..... | 32 | +| Appendix VII – Analysis of conversion of network limits to equipment specification for APTS ..... | 33 | +| VII.1 Total noise budget between network limits..... | 33 | +| VII.2 Holdover operation..... | 34 | +| VII.3 Transient operation and switching..... | 35 | +| VII.4 Dynamic noise accumulation for APTS ..... | 35 | +| Appendix VIII – Analysis of conversion of network limits to equipment specification for PTS ..... | 37 | +| VIII.1 Total noise between network limit C and network limit D ..... | 37 | +| VIII.2 Holdover operation..... | 38 | +| VIII.3 Transient operation and switching..... | 38 | +| VIII.4 Dynamic noise accumulation for PTS (constant temperature)..... | 38 | +| Bibliography..... | 40 | + +# Recommendation ITU-T G.8273.4 + +# Timing characteristics of telecom boundary clocks and telecom time synchronous clocks for use with partial timing support from the network + +## 1 Scope + +This Recommendation specifies the minimum requirements for time and phase synchronization equipment used in synchronization networks that operates in the assisted partial timing support (APTS) and partial timing support (PTS) architectures. + +The APTS and PTS architectures are specified in [ITU-T G.8271], [ITU-T G.8271.2] and [ITU-T G.8275]. The applicable profile is established in [ITU-T G.8275.2], which specifies unicast PTS/APTS time or phase synchronization distribution for packet-based networks. + +This Recommendation allows for proper network operation for phase/time synchronization distribution when a network equipment embedding an APTS or a PTS clock is timed from another telecom boundary clock (T-BC) or a telecom grandmaster (T-GM). This Recommendation specifies the minimum requirements for APTS and PTS clocks in network elements (NEs), applicable under the normal environmental conditions specified for the equipment. + +This Recommendation includes noise generation, noise tolerance, noise transfer, and transient response for APTS and PTS clocks. + +Synchronous equipment clocks (per [ITU-T G.8262]) are optional in this Recommendation, and they are not used for APTS. For PTS, if a piece of equipment implements a synchronous equipment clock, as described in Appendix III and in Appendix IV, then the requirements in clause 8 still apply. + +NOTE – For APTS, double failure (coincident failure of both global navigation satellite system (GNSS) and precision time protocol (PTP) input references) is not addressed in this Recommendation, except for short-term holdover scenarios (see clause 7.6.1) where the primary GNSS source is lost and a backup PTP source is temporarily unavailable. APTS double failure is for further study. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.703] Recommendation ITU-T G.703 (2016), *Physical/electrical characteristics of hierarchical digital interfaces*. +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2020), *Interfaces for the optical transport network* +- [ITU-T G.781] Recommendation ITU-T G.781 (2024), *Synchronization layer functions for frequency synchronization based on the physical layer*. +- [ITU-T G.810] Recommendation ITU-T G.810 (1996), *Definitions and terminology for synchronization networks*. +- [ITU-T G.811] Recommendation ITU-T G.811 (1997), *Timing characteristics of primary reference clocks*. + +- [ITU-T G.813] Recommendation ITU-T G.813 (2003), *Timing characteristics of SDH equipment slave clocks (SEC)*. +- [ITU-T G.8260] Recommendation ITU-T G.8260 (2022), *Definitions and terminology for synchronization in packet networks*. +- [ITU-T G.8262] Recommendation ITU-T G.8262 (2024), *Timing characteristics of a synchronous equipment clock*. +- [ITU-T G.8264] Recommendation ITU-T G.8264/Y.1364 (2017), *Distribution of timing information through packet networks*. +- [ITU-T G.8271] Recommendation ITU-T G.8271/Y.1366 (2020), *Time and phase synchronization aspects of telecommunication networks*. +- [ITU-T G.8271.2] Recommendation ITU-T G.8271.2/Y.1366.2 (2021), *Network limits for time synchronization in packet networks with partial timing support from the network*. +- [ITU-T G.8272] Recommendation ITU-T G.8272/Y.1367 (2018), *Timing characteristics of primary reference time clocks*. +- [ITU-T G.8273.2] Recommendation ITU-T G.8273.2/Y.1368.2 (2023), *Timing characteristics of telecom boundary clocks and telecom time synchronous clocks for use with full timing support from the network*. +- [ITU-T G.8275] Recommendation ITU-T G.8275 (2024), *Architecture and requirements for packet-based time and phase distribution*. +- [ITU-T G.8275.2] Recommendation ITU-T G.8275.2/Y.1369.2 (2022), *Precision time protocol telecom profile for phase/time synchronization with partial timing support from the network*. + +## 3 Definitions + +### 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +Terms related to synchronization are defined in [ITU-T G.810] and [ITU-T G.8260]. + +### 3.2 Terms defined in this Recommendation + +None. + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|--------------------------------------------| +| APTS | Assisted Partial Timing Support | +| BTCA | Best TimeTransmitter Clock Algorithm | +| cTE | constant Time Error | +| dTE | dynamic Time Error | +| EEC | Ethernet Equipment Clock | +| ESMC | Ethernet Synchronization Messaging Channel | +| GbE | Gigabit Ethernet | +| GNSS | Global Navigation Satellite System | + +| | | +|---------|--------------------------------------------------------------------| +| I/O | Input/Output | +| IWF | Interworking Function | +| MTIE | Maximum Time Interval Error | +| NE | Network Element | +| OSMC | OTN Synchronization Message Channel | +| OTN | Optical Transport Network | +| PEC | Packet-based Equipment Clock | +| P-F | PTS to full timing support (FTS) | +| PPS | Pulse Per Second | +| PRC | Primary Reference Clock | +| PRS | Primary Reference Source | +| PRTC | Primary Reference Time Clock | +| PTP | Precision Time Protocol | +| PTS | Partial Timing Support | +| SDH | Synchronous Digital Hierarchy | +| SEC | Synchronous Equipment Clock (NOTE – see Conventions) | +| SSM | Synchronization Status Message | +| STM-N | Synchronous Transport Module – level N | +| SyncE | Synchronous Ethernet | +| T-BC | Telecom Boundary Clock | +| T-BC-A | Telecom Boundary Clock for Assisted partial timing support | +| T-BC-P | Telecom Boundary Clock for Partial timing support | +| TE | Time Error | +| T-GM | Telecom Grandmaster | +| ToD | Time of Day | +| TR | timeReceiver | +| TT | timeTransmitter | +| T-TSC-A | Telecom Time Synchronous Clock for Assisted partial timing support | +| T-TSC-P | Telecom Time Synchronous Clock for Partial timing support | + +## 5 Conventions + +SEC: synchronous equipment clock: A generic term representing the SDH equipment clock ([ITU-T G.813]), the Ethernet equipment clock (EEC) and the optical transport network (OTN) equipment clock, which are defined in [ITU-T G.8262]. + +# 6 Physical layer frequency performance requirements + +Synchronous equipment clock interfaces and the synchronous equipment clock are optional in this Recommendation. When used on the telecom time synchronous clock for partial timing support (T-TSC-P) or telecom boundary clock (T-BC) for partial timing support (T-BC-P), the synchronous + +equipment clock shall meet the performance requirements specified in [ITU-T G.8262]. It shall generate and process Ethernet synchronization messaging channel (ESMC) messages as specified in [ITU-T G.8264]. For OTN equipment, it shall generate and process OTN synchronization message channel (OSMC) to transport SSM messages as specified in [ITU-T G.709]. + +Synchronous digital hierarchy (SDH) interfaces and SDH equipment clocks are optional. When used on the T-TSC-P or T-BC-P, the SDH equipment clocks shall meet the performance requirements specified in [ITU-T G.813], and shall generate and process synchronization status messages (SSMs) as specified in [ITU-T G.781]. + +# 7 Performance requirements for T-BC-A and T-TSC-A + +### 7.1 Frequency accuracy + +Under free-running conditions, the clock output frequency accuracy should not exceed 4.6 ppm with respect to a reference traceable to an [ITU-T G.811] or [ITU-T G.8272] clock. + +### 7.2 Time error noise generation + +The time error (TE) noise generation of a telecom boundary clock for assisted partial timing support (APTS) (T-BC-A) and telecom time synchronous clock for assisted partial timing support (T-TSC-A) represents the amount of noise (i.e., TE) produced at the output of the T-BC-A/T-TSC-A when locked to an ideal, wander-free time reference at the 1 pulse per second (1 PPS) or precision time protocol (PTP) time input (see Figure A.1). This is equivalent to having an external local time reference at reference point L, as shown in Figure 1 of [ITU-T G.8271.2]. + +If an external local time reference is connected using a PTP timing signal instead of a 1 PPS signal, the TE noise generation is for further study. + +In the case of an integrated local time reference (e.g., a global navigation satellite system (GNSS) signal at the time input), there may not be an accessible 1 PPS or PTP time input. In this case, the requirements of this clause are not applicable, except for the maximum TE noise generation, which is under further study. + +The output of the T-BC-A is measured at both the 1 PPS output and packet input/output (I/O) PTP timeTransmitter (TT) port; the output of the T-TSC-A is measured at the 1 PPS output. + +NOTE – The values in in this clause are valid for 1 PPS interfaces and for 1 gigabit Ethernet (gigabit Ethernet (GbE)), 10 GbE, 25 GbE, 40 GbE and 100 GbE interfaces. Values for other interfaces are for further study. + +#### 7.2.1 Maximum absolute time error (max|TE|) noise generation + +Under normal, locked operating conditions, the time output of the T-BC-A and the T-TSC-A should be accurate to within the maximum absolute TE (max|TE|). This value includes all noise components, i.e., the constant time error (cTE) and the dynamic time error (dTE). + +The max|TE| limit is for further study. + +In the case of an integrated local time reference, the max|TE| value is 100 ns greater than the value for an external local time reference. The total value is also for further study. + +#### 7.2.2 Constant time error generation + +The permissible range of cTE noise generation is shown in Table 7-1. + +**Table 7-1 – T-BC-A/T-TSC-A permissible range of constant time error** + +| T-BC-A/T-TSC-A class | Permissible range of cTE (ns) | +|----------------------|-------------------------------| +| A | ±50 | +| B | ±20 | + +NOTE 1 – The cTE definition and its method of estimation are given in [ITU-T G.8260]. For the purpose of testing the limits in Table 7-1, an estimate of cTE should be obtained by averaging the TE sequence over at least 10 000 s. + +NOTE 2 – The cTE is measured at constant temperature (within ±1 K). + +#### 7.2.3 Dynamic time error low-pass filtered noise generation + +The dynamic TE low-pass filtered noise generation (dTEL) is a maximum of 50 ns peak-to-peak. + +NOTE – This should be measured under constant temperature (within ±1 K) and using a first-order low-pass measurement filter with a bandwidth of 0.1 Hz for a minimum of 10 000 s. + +#### 7.2.4 Dynamic time error high-pass filtered noise generation + +The dynamic TE high-pass filtered noise generation (dTEH) is for further study. + +### 7.3 Noise tolerance + +The noise tolerance of the equipment clock indicates the minimum TE level at the clock's input that should be accommodated while not causing: + +- any alarms; +- the clock to switch reference; +- the clock to go into holdover. + +An equipment clock must be capable of tolerating the following levels of noise at its time input: + +- max|TE| according to clause 7.1 of [ITU-T G.8271.2] network limit + +NOTE 1 – This requirement on the time input is not applicable in the case of an integrated local time reference (e.g., a GNSS signal at the time input). + +In the event of a failure of the time input, when the backup PTP input is selected, an equipment clock must be capable of tolerating the following levels of noise at its PTP input: + +- peak-to-peak pktSelected2wayTE according to clause 7.3.1 of [ITU-T G.8271.2] network limit + +In addition, a T-TSC-A and a T-BC-A must maintain the max|TEL| at its 1 PPS output(s), and in the case of a T-BC-A on its PTP output(s), below the level indicated in clause 7.4.1 of [ITU-T G.8271.2]. + +NOTE 2 – To compute max|TEL|, a first-order low-pass measurement filter with bandwidth of 0.1 Hz is used, and it is applied to the TE samples measured at the 1 PPS output and PTP output(s) prior to evaluating the max|TE|. + +NOTE 3 – For T-TSC-A and T-BC-A clocks, a network asymmetry can be present as additional |cTE| at the PTP input of the clock, apart from the peak-to-peak pktSelected2wayTE specified above. + +### 7.4 Local time reference (1 PPS) to PTP and local time reference (1 PPS) to 1 PPS noise transfer + +The phase gain of the T-BC-A or T-TSC-A should be smaller than 0.1 dB (1.1%). + +### 7.5 PTP output and 1 PPS output transient response (short term) due to loss and restoration of local time reference (1 PPS) input + +The requirements in this clause describe the performance of the clock if the local time reference input is ideal. + +The response of the T-BC-A and T-TSC-A due to the loss and restoration of the local time reference may be generalized by the following sequence of events: + +- the clock is locked to the local time reference; +- the local time reference is lost; +- the clock enters holdover; +- the clock maintains holdover state; +- the local time reference is restored; +- the clock selects the local time reference; +- the clock is locked to the local time reference. + +The following requirements apply: + +- 1) upon the loss of the local time reference, the initial transient response needs to be less than 22 ns. This is referenced in clause 7.6 as parameter 'c'; +- 2) in addition, the phase error needs to be within the requirements of clause 7.6 for the duration of the loss of the local time reference; +- 3) upon restoration of the local time reference, the phase is corrected to align with the local time reference and eliminate the phase error accumulated during holdover. The allowed transient response of the clock depends on the duration of the loss of the local time reference and the allowed phase error during holdover as specified in clause 7.6. + +### 7.6 Holdover performance + +#### 7.6.1 Holdover based on oscillator + +This requirement bounds the maximum excursions in the output timing signal. + +It specifies the phase/time performance of the T-BC-A or T-TSC-A clock if an ideal local time reference input is disconnected, and the backup PTP time source from the network cannot be used (e.g., during a switching process or very short unavailability of the PTP source). This offers temporary assistance (up to the limit indicated in Figure 7-1) to maintain phase/time previously set by the primary timeTransmitter. Other failure scenarios are for further study, including that in which the primary GNSS source is the first to be lost and the PTP is used as backup source for some time before finally failing. + +When a T-BC-A or T-TSC-A clock loses all its references, it enters the holdover state. The phase error, $\Delta T$ , at the output of T-BC-A/T-TSC-A relative to the input at the moment of loss of reference should meet the following: + +$$|\Delta T(t)| \leq [(a_1 + a_2)t + 0.5bt^2 + c] \quad (\text{ns})$$ + +where: + +$$a_1 = 1 \text{ ns/s (see Note 1);}$$ + +$$a_2 = \text{for further study (see Note 2);}$$ + +$$b = 1.16 \times 10^{-5} \text{ ns/s}^2 \text{ (see Note 3);}$$ + +$$c = 22 \text{ ns (see Note 4).}$$ + +NOTE 1 – The frequency offset $a_1$ represents an initial frequency offset corresponding to 1 ns/s. + +NOTE 2 – The frequency offset $a_2$ accounts for temperature variations after the clock goes into holdover and requires further study. If there are no temperature variations, the term $a_2$ should not contribute to the phase error; thus, for constant temperature, $a_2 = 0$ ns/s. + +NOTE 3 – The drift $b$ is caused by ageing: $1.16 \times 10^{-5}$ ns/s2 corresponds to a frequency drift of $1 \times 10^{-9}$ /day (1 ppb/day). + +NOTE 4 – The phase offset $c$ takes accounts for any additional phase shift that may arise during the transition at the entry into and exit from the holdover state. + +Under constant temperature conditions (within $\pm 1$ K) the maximum observation interval is 1 000 s. The resultant overall requirement for constant temperature (i.e., when the temperature effect is negligible) is summarized in Figure 7-1. + +$$|\Delta T(t)| \leq (a_1 t + 0.5 b t^2 + c) \quad (\text{ns})$$ + +![Figure 7-1: A log-log plot showing the permissible phase error ΔT (ns) versus time t (s). The y-axis ranges from 10 ns to 1 μs, and the x-axis ranges from 1 s to 1000 s. The curve starts at approximately 20 ns at 1 s and increases to 1 μs at 1000 s. The plot is labeled G.8273.4-Y.1368.4(20)_F7-1.](8791f79b259a7463279c1aeb14c31580_img.jpg) + +The figure is a log-log plot showing the permissible phase error $\Delta T$ in nanoseconds (ns) on the y-axis against time $t$ in seconds (s) on the x-axis. The y-axis has major ticks at 10 ns, 100 ns, and 1 μs. The x-axis has major ticks at 1, 10, 100, and 1000 s. A blue curve starts at approximately 20 ns at 1 s and increases to 1 μs at 1000 s. The curve is labeled G.8273.4-Y.1368.4(20)\_F7-1. + +Figure 7-1: A log-log plot showing the permissible phase error ΔT (ns) versus time t (s). The y-axis ranges from 10 ns to 1 μs, and the x-axis ranges from 1 s to 1000 s. The curve starts at approximately 20 ns at 1 s and increases to 1 μs at 1000 s. The plot is labeled G.8273.4-Y.1368.4(20)\_F7-1. + +Figure 7-1 – Permissible phase error under holdover operation at constant temperature + +#### 7.6.2 Holdover based on PTP + +This clause describes the phase/time performance of a T-BC-A or T-TSC-A during loss of the local time reference based on the use of a PTP input as a backup source of time or frequency. + +This requirement reflects the performance of the clock if the local time reference input is ideal followed by disconnection of the local time reference input after a stabilization period. The PTP input is ideal. + +Under constant temperature conditions (within $\pm 1$ K) the maximum observation interval is 10 000 s. + +**Table 7-2 – Performance allowance during loss of local time reference input (maximum time interval error (MTIE)) for T-BC-A or T-TSC-A with constant temperature** + +| MTIE limit (ns) | Observation interval $\tau$ (s) | +|-----------------|---------------------------------| +| $200 + c$ | $1 \leq \tau \leq 10\,000$ | + +Here $c = 22$ ns (see Note 1). +NOTE 1 – The phase offset $c$ is associated with the phase transient response from clause 7.5. +NOTE 2 – The main contributor to the holdover performance is the noise generation of the equipment clock when locked to a PTP input. The value of 200 ns is consistent with the noise generation in clause 8.2.3. + +## 8 Performance requirements for T-BC-P and T-TSC-P + +### 8.1 Frequency accuracy + +Under free-running conditions, the clock output frequency accuracy should not be greater than 4.6 ppm with respect to a reference traceable to a [ITU-T G.811] or [ITU-T G.8272] clock. + +### 8.2 Time error noise generation + +The TE noise generation of a T-BC-P or T-TSC-P represents the amount of noise (i.e., TE) produced at the output of the T-BC-P or T-TSC-P when locked to an ideal, wander-free PTP time reference at the packet I/O PTP TR port (see Figure B.1). + +The output of the T-BC-P is measured at both the 1 PPS output and packet I/O PTP timeTransmitter port; the output of the T-TSC-P is measured at the 1 PPS output. + +NOTE – The values in this clause are valid for 1 PPS interfaces and for 1 GbE, 10 GbE, 25 GbE, 40 GbE and 100 GbE interfaces. Values for other interfaces are for further study. + +#### 8.2.1 Maximum absolute time error noise generation (max|TE|) + +Under normal, locked operating conditions, the time output of the T-BC-P and the T-TSC-P should be accurate to within the max|TE| limit. This value includes all the noise components, i.e., the cTE and the dTE. + +The max|TE| noise generation limit is for further study. + +#### 8.2.2 Constant time error noise generation + +The permissible range of cTE noise generation is shown in Table 8-1. + +**Table 8-1 – T-BC-P/T-TSC-P permissible range of constant time error** + +| T-BC-P/T-TSC-P class | Permissible range of cTE (ns) | +|----------------------|-------------------------------| +| A | $\pm 50$ | +| B | $\pm 20$ | + +NOTE 1 – The definition of cTE and its method of estimation are found in clause 3.1.20 of [ITU-T G.8260]. For testing the limits in Table 8-1, an estimate of cTE should be obtained by averaging the TE sequence over at least 10 000 s. + +NOTE 2 – The cTE is measured at constant temperature (within $\pm 1$ K). + +#### 8.2.3 Dynamic time error low-pass filtered noise generation + +The dTEL is a maximum of 200 ns peak-to-peak. + +NOTE – This should be measured under constant temperature (within $\pm 1$ K) and using a first-order low-pass measurement filter with a bandwidth of 0.1 Hz for a minimum of 10 000 s. + +#### **8.2.4 Dynamic time error high-pass filtered noise generation** + +The $dTE_H$ is for further study. + +### **8.3 Noise tolerance** + +The noise tolerance of the equipment clock indicates the minimum TE level at the input of the clock that should be accommodated while not causing: + +- any alarms; +- the clock to switch reference; +- the clock to go into holdover. + +An equipment clock must be capable of tolerating the following levels of noise at its input: + +- $\max|pktSelected2wayTE|$ according to the network limit given in clause 7.3.2.1 of [ITU-T G.8271.2] at the PTP input; +- wander tolerance according to clause 9.1 of [ITU-T G.8262] at the synchronous equipment clock input; + +In addition, a T-TSC-P and a T-BC-P must maintain the $\max|TE_L|$ at its 1 PPS output(s), and in the case of a T-BC-P on its PTP output(s), below the level indicated in clause 7.4.2 of [ITU-T G.8271.2]. + +NOTE – To compute $\max|TE_L|$ , a first-order low-pass measurement filter with bandwidth of 0.1 Hz is used, applied to the TE samples measured at the 1 PPS output and PTP output(s) prior to evaluating the $\max|TE|$ . + +### **8.4 Noise transfer** + +#### **8.4.1 PTP to PTP and PTP to 1 PPS noise transfer** + +The phase gain of the T-BC-P or T-TSC-P should be smaller than 0.1 dB (1.1%). + +#### **8.4.2 Physical layer frequency assistance to PTP and physical layer frequency assistance to 1 PPS noise transfer** + +The noise transfer specification in the case of physical layer frequency assistance is for further study. For more information on the use of synchronous Ethernet (SyncE) to assist a partially aware clock, refer to Appendix IV. + +### **8.5 Transient response (short-term)** + +#### **8.5.1 PTP output and 1 PPS output transient response due to loss and restoration or switching of PTP input** + +The requirements in this clause reflect the performance of the clock if the PTP input is ideal. + +The response of the T-BC-P and T-TSC-P due to the loss and restoration of PTP may be generalized by the following sequence events: + +- the clock is locked to a PTP reference; +- the PTP reference is lost; +- the clock enters holdover; +- the clock maintains holdover state; +- a PTP reference is available; +- the clock selects the PTP reference; +- the clock is locked to the PTP reference. + +The following requirements apply: + +- 1) the transient response due to the loss of the PTP reference shall be less than 22 ns MTIE; +- 2) the period of loss of PTP while in holdover shall comply with clause 8.6; +- 3) the transient response due to the restoration of the PTP shall be less than 22 ns MTIE. + +#### **8.5.2 PTP output and 1 PPS output transient response due to switching physical layer input while maintaining PTP input** + +PTP output and 1 PPS output transient response due to switching physical layer input while maintaining PTP input are for further study. + +#### **8.5.3 PTP output and 1 PPS output transient response due to switching simultaneously the physical layer input and the PTP input** + +PTP output and 1 PPS output transient response due to switching physical layer input while maintaining PTP input are for further study. + +### **8.6 Holdover performance** + +#### **8.6.1 Holdover based on oscillator** + +The phase/time performance during loss of the PTP input based on a local oscillator applicable to a T-BC-P or T-TSC-P is as follows. + +This requirement bounds the maximum excursions in the output timing signal. + +This requirement reflects the performance of the clock if the PTP input is ideal, followed by disconnection of the PTP input. + +When a T-BC-P or T-TSC-P clock loses all its references, it enters the holdover state. The phase error, $\Delta T$ , at the output of the T-BC-P/T-TSC-P relative to the input at the moment of loss of reference should meet the following condition: + +$$|\Delta T(t)| \leq [(a_1 + a_2)t + 0.5bt^2 + c] \quad (\text{ns})$$ + +where: + +$$a_1 = 1 \text{ ns/s (see Note 1);}$$ + +$$a_2 = \text{for further study (see Note 2);}$$ + +$$b = 1.16 \times 10^{-5} \text{ ns/s}^2 \text{ (see Note 3);}$$ + +$$c = 22 \text{ ns (see Note 4).}$$ + +NOTE 1 – The frequency offset $a_1$ represents an initial frequency offset corresponding to 1 ns/s. + +NOTE 2 – The frequency offset $a_2$ accounts for temperature variations after the clock went into holdover and requires further study. If there are no temperature variations, the term $a_2$ should not contribute to the phase error; thus, for constant temperature, $a_2 = 0 \text{ ns/s}$ . + +NOTE 3 – The drift $b$ is caused by ageing: $1.16 \times 10^{-5} \text{ ns/s}^2$ corresponds to a frequency drift of $1 \times 10^{-9}/\text{day}$ (1 ppb/day). + +NOTE 4 – The phase offset $c$ accounts for any additional phase shift that may arise during the transition at the entry into and exit from the holdover state. + +Under constant temperature conditions (within $\pm 1 \text{ K}$ ), the maximum observation interval is 1 000 seconds. The resultant overall requirement for constant temperature (i.e., when the temperature effect is negligible) is summarized in Figure 8-1. + +$$|\Delta T(t)| \leq (a_1 t + 0.5bt^2 + c) \quad (\text{ns})$$ + +![Figure 8-1: A log-log plot showing the permissible phase error ΔT (in seconds) versus time t (in seconds) under holdover operation at constant temperature. The y-axis ranges from 10 ns to 1 μs, and the x-axis ranges from 1 s to 1000 s. The curve starts at approximately 20 ns at 1 s and increases linearly to 1 μs at 1000 s. The plot is labeled G.8273.4-Y.1368.4(20)-Amd.1(21)_F8-1.](1d529a819ad929684331c55eed6673bb_img.jpg) + +| Time $t$ (s) | Phase Error $\Delta T$ (s) | +|--------------|------------------------------| +| 1 | $2 \times 10^{-8}$ (20 ns) | +| 10 | $6.3 \times 10^{-8}$ (63 ns) | +| 100 | $2 \times 10^{-7}$ (200 ns) | +| 1000 | $1 \times 10^{-6}$ (1 μs) | + +Figure 8-1: A log-log plot showing the permissible phase error ΔT (in seconds) versus time t (in seconds) under holdover operation at constant temperature. The y-axis ranges from 10 ns to 1 μs, and the x-axis ranges from 1 s to 1000 s. The curve starts at approximately 20 ns at 1 s and increases linearly to 1 μs at 1000 s. The plot is labeled G.8273.4-Y.1368.4(20)-Amd.1(21)\_F8-1. + +**Figure 8-1 – Permissible phase error under holdover operation at constant temperature** + +#### 8.6.2 Holdover based on physical layer frequency assistance + +When a T-BC-P or T-TSC-P loses all of its input phase and time references, it enters the phase/time holdover state. Under these circumstances, the T-BC-P or T-TSC-P may rely on a physical layer frequency assistance reference traceable to a primary reference clock (PRC). + +This requirement reflects the performance of the clock if an ideal PTP input is disconnected. The physical layer frequency input is also ideal. + +The requirements on phase/time performance during loss of the PTP input reference are defined in clause 7.4.2.2 of [ITU-T G.8273.2]. + +## 9 Interfaces + +The requirements in this Recommendation are related to reference points that may be internal to the equipment or NE in which the T-BC-A, T-BC-P, T-TSC-A or T-TSC-P is embedded, and are therefore not necessarily available for measurement or analysis by the user. Consequently, the performance of the T-BC-A, T-BC-P, T-TSC-A or T-TSC-P is not specified at these internal reference points, but rather at the external interfaces of the equipment. + +Note that not all interfaces mentioned in this clause need to be implemented on all equipment. + +Table 9-1 summarizes the differences with respect to interfaces between different clock types and the applicability of clauses of this Recommendation to the T-TSC-A, T-TSC-P, T-BC-A and T-BC-P equipment clocks. The following terms are used: + +- "applicable" means requirements apply to the clock; +- "optional" means requirements apply to the clock if the optional local time reference input is supported; +- "not Applicable" means that the PTP output is not available on the equipment clock. + +**Table 9-1 – Differences with respect to interfaces between different clock types** + +| Equipment clock | Local time reference input | PTP output | +|------------------------|-----------------------------------|-------------------| +| T-TSC-A | Applicable | Not applicable | +| T-TSC-P | Not applicable | Not applicable | +| T-BC-A | Applicable | Applicable | +| T-BC-P | Not applicable | Applicable | + +### **9.1 Phase and time interfaces** + +The phase and time interfaces specified for the equipment in which the T-BC-A, T-BC-P, T-TSC-A or T-TSC-P may be contained are: + +- Ethernet interface carrying PTP messages; +NOTE – Ethernet interfaces can combine SyncE for frequency and PTP messages. These interfaces may also carry other traffic in addition to PTP traffic. +- ITU-T V.11-based time/phase distribution interface, as specified in [ITU-T G.703] and [ITU-T G.8271]; +- 1 PPS 50 Ω phase-synchronization measurement interface, as specified in [ITU-T G.703] and [ITU-T G.8271]; +- Interface carrying GNSS signal; +- other interfaces are for further study. + +### **9.2 Frequency interfaces** + +The frequency interfaces specified for the equipment in which the T-BC-P, or T-TSC-P may be contained are: + +- 2 048 kHz interfaces according to [ITU-T G.703] with additional wander requirements as specified herein; +- 1 544 kbit/s interfaces according to [ITU-T G.703] with additional wander requirements as specified herein; +- 2 048 kbit/s interfaces according to [ITU-T G.703] with additional wander requirements as specified therein; +- synchronous transport module – level N (STM-N) traffic interfaces; +- SyncE interfaces; +NOTE – Ethernet interfaces can combine PTP and SyncE. These interfaces may also carry other traffic in addition to PTP and ESMC traffic. +- other interfaces are for further study. + +## Annex A + +### T-TSC-A and T-BC-A functional model + +(This annex forms an integral part of this Recommendation.) + +Figure A.1 illustrates the T-TSC-A and T-BC-A functional model. + +![Functional model diagram of T-TSC-A and T-BC-A. The diagram is enclosed in a dashed box and divided into two sides: TR side and TT side. On the TR side, a 'Time input (e.g., GNSS, PTP, 1 PPS + ToD)' enters a 'Time source clock' block. This block connects to a 'Time selection' block and a 'PEC(s)' block. The 'PEC(s)' block connects to a 'Packet processing' block, which has an external 'Packet I/O' interface. The 'Time selection' block connects to a 'Time and frequency generation' block. The 'TT side' contains a 'Timing service monitor' block, a 'Frequency selection' block, and another 'Packet processing' block. The 'Frequency selection' block connects to the 'Time and frequency generation' block and the 'Packet processing' block. The 'Packet processing' block on the TT side has an external 'Packet I/O' interface. The 'Time and frequency generation' block produces three outputs: 'Frequency output (e.g., 2 048 kHz)', '1 PPS output', and 'ToD output'.](10781f43062bf3e9601a1e086710556c_img.jpg) + +Functional model diagram of T-TSC-A and T-BC-A. The diagram is enclosed in a dashed box and divided into two sides: TR side and TT side. On the TR side, a 'Time input (e.g., GNSS, PTP, 1 PPS + ToD)' enters a 'Time source clock' block. This block connects to a 'Time selection' block and a 'PEC(s)' block. The 'PEC(s)' block connects to a 'Packet processing' block, which has an external 'Packet I/O' interface. The 'Time selection' block connects to a 'Time and frequency generation' block. The 'TT side' contains a 'Timing service monitor' block, a 'Frequency selection' block, and another 'Packet processing' block. The 'Frequency selection' block connects to the 'Time and frequency generation' block and the 'Packet processing' block. The 'Packet processing' block on the TT side has an external 'Packet I/O' interface. The 'Time and frequency generation' block produces three outputs: 'Frequency output (e.g., 2 048 kHz)', '1 PPS output', and 'ToD output'. + +G.8273.4(24) + +**Figure A.1 – The T-TSC-A and T-BC-A functional model** + +NOTE 1 – Figure A.1 is a functional model. It is not intended to specify any specific implementation. Any implementation specific detail lies outside the scope of this Recommendation. + +NOTE 2 – Not all interfaces are required to be present in an implementation. + +NOTE 3 – Not all functional blocks are required to be present in an implementation. + +NOTE 4 – The functional model shows interfaces that lie within the scope of this Recommendation; additional functions and interfaces can be integrated in a specific implementation, but are not shown in the functional model. + +Table A.1 describes the functionality of the blocks depicted in Figure A.1. + +**Table A.1 – T-TSC-A and T-BC-A clock model functional blocks** + +| Functional block label | Functionality | +|-------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Time and frequency generation | Generates the local time scale of the clock (local PTP clock) using the time source information supplied by the time selection block and frequency source information supplied by the frequency selection block. | +| Time selection | Selects the local time source to be used by the clock from among various possible available time inputs. In normal deployment, the time source clock will be the primary time input, with the PEC providing a secondary time source for backup purposes. This block may support combining more than one time source. | +| Frequency selection | Selects the local frequency source to be used by the clock from among various possible available frequency inputs. In normal deployment, the time source clock will be the primary frequency input, with the PEC providing a secondary frequency source for backup. | + +**Table A.1 – T-TSC-A and T-BC-A clock model functional blocks** + +| Functional block label | Functionality | +|------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Packet processing |

On the TR side, processes ingress PTP packets according to the PTP profile and passes the timestamps from these PTP packets to the PEC. Generates egress PTP packets according to the PTP profile and passes the timestamps from these PTP packets to the PEC.

In the case of the T-BC-A, on the TT side, processes ingress PTP packets and generates egress PTP packets according to the PTP profile. Time-stamping is based on the local time scale (local PTP clock) provided by the time and frequency generation block.

| +| Timing service monitor |

Provides monitoring of the timing service received by the clock according to key performance indicators. As an example, it may monitor the PTP timing service by analysing the PTP timestamps from the packet processing block (TR side) when the local time scale is following a stable time reference source from the time source clock.

| +| Time source clock |

Synchronizes to a time reference (e.g., GNSS, PTP, 1 PPS and time of day (ToD)) and provides this as a time reference to the time selection block, as well as a frequency reference to the frequency selection block. Provides time reference to the PEC(s) for asymmetry compensation.

| +| PEC(s) |

Synchronizes to a PTP timeTransmitter, using PTP timestamps from the packet processing (TR side) block, and provides this as a time reference to the time selection block or as a frequency reference to the frequency selection block. Receives time reference from the time source clock for asymmetry compensation.

| + +Table A.2 describes the functionality of the interfaces depicted in Figure A.1. + +**Table A.2 – T-TSC-A and T-BC-A clock model external interfaces** + +| External interfaces label | Functionality | +|----------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Packet I/O |

Interfaces to transmit and receive PTP packets from the packet processing block. On the TR side, it will act as a PTP port in the timeReceiver (TR) state to interact with external PTP timeTransmitter devices, and on the TT side it will act as a PTP port in the timeTransmitter state to interact with external PTP timeReceiver devices. The PTP reference received on the TR port is used as a backup time or frequency reference in the event of a failure of the primary time input reference.

| +| Time input
(e.g., GNSS, PTP, 1 PPS + ToD) |

Time interface to receive from applicable interfaces available on the clock (e.g., GNSS, PTP, 1 PPS phase input and ToD serial time information). Provides timing information to the time source clock block. This interface is the primary time and frequency input reference to the device. This interface corresponds to reference point L in Figure 1 of [ITU-T G.8271.2].

| + +**Table A.2 – T-TSC-A and T-BC-A clock model external interfaces** + +| External interfaces label | Functionality | +|---------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------| +| 1 PPS output | 1 PPS phase output ([ITU-T G.703]) generated by the time and frequency generation block. | +| ToD output | ToD serial time information output generated by the time and frequency generation block. | +| Frequency output
(e.g., 2 048 kHz) | Frequency output (e.g., [ITU-T G.703] 2 048 kHz) provides frequency information. Generated by the time and frequency generation block. | + +## Annex B + +### T-TSC-P and T-BC-P functional model + +(This annex forms an integral part of this Recommendation.) + +Figure B.1 illustrates the T-TSC-P and T-BC-P functional model. + +![Functional model diagram of T-TSC-P and T-BC-P. The diagram shows a central 'Time and frequency generation' block connected to 'PEC(s)', 'Packet processing' (TR and TT sides), 'Frequency selection', 'Timing service monitor', and 'Physical layer clock (e.g., EEC/SEC)'. External inputs include 'Packet I/O', 'Physical layer frequency input (e.g., SyncE)', and 'External frequency 2 048 kHz'. External outputs include 'Frequency output (e.g., 2 048 kHz)', '1 PPS output', 'ToD output', 'Packet I/O', and 'Physical layer frequency output (e.g., SyncE)'. The diagram is divided into 'TR side' and 'TT side' by a dashed line, with a 'Physical layer' block at the bottom.](09955ff8214ffb6947951fc0f60eb6ab_img.jpg) + +Functional model diagram of T-TSC-P and T-BC-P. The diagram shows a central 'Time and frequency generation' block connected to 'PEC(s)', 'Packet processing' (TR and TT sides), 'Frequency selection', 'Timing service monitor', and 'Physical layer clock (e.g., EEC/SEC)'. External inputs include 'Packet I/O', 'Physical layer frequency input (e.g., SyncE)', and 'External frequency 2 048 kHz'. External outputs include 'Frequency output (e.g., 2 048 kHz)', '1 PPS output', 'ToD output', 'Packet I/O', and 'Physical layer frequency output (e.g., SyncE)'. The diagram is divided into 'TR side' and 'TT side' by a dashed line, with a 'Physical layer' block at the bottom. + +**Figure B.1 – T-TSC-P and T-BC-P functional model** + +NOTE 1 – Figure B.1 is a functional model. It is not intended to specify any specific implementation. Any implementation specific detail lies outside the scope of this Recommendation. + +NOTE 2 – Not all interfaces are required to be present in an implementation. + +NOTE 3 – Not all functional blocks are required to be present in an implementation. + +NOTE 4 – The functional model shows interfaces that lie within the scope of this Recommendation; additional functions and interfaces can be integrated in a specific implementation, but are not shown in the functional model. + +Table B.1 describes the functionality of the blocks depicted in Figure B.1. + +**Table B.1 – T-TSC-P and T-BC-P clock model functional blocks** + +| Functional block label | Functionality | +|-------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Time and frequency generation | Generates the local time scale of the clock (local PTP clock) using the time source information supplied by the time selection block and frequency source information supplied by the frequency selection block. | +| Frequency selection | Selects the local frequency source to be used by the clock from among various possible available frequency inputs, including the time source clock, PEC and physical layer clock. | + +**Table B.1 – T-TSC-P and T-BC-P clock model functional blocks** + +| Functional block label | Functionality | +|--------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Packet processing |

On the TR side, processes ingress PTP packets according to the PTP profile and passes the timestamps from these PTP packets to the PEC. Generates egress PTP packets according to the PTP profile and passes the timestamps from these PTP packets to the PEC.

In the case of the T-BC-P, on the TT side, processes ingress PTP packets and generates egress PTP packets according to the PTP profile.

Time-stamping is based on the local time scale (local PTP clock) provided by the time and frequency generation block.

| +| Timing service monitor |

Provides monitoring of the timing service received by the clock according to key performance indicators. As an example, it may monitor the PTP timing service by analysing the PTP timestamps from the packet processing block (TR side) when the local time scale is following a stable time reference source from the time source clock.

| +| PEC |

Synchronizes to a PTP TT, using PTP timestamps from the packet processing (TR side) block, and provides this is as a time reference to the time selection block or as a frequency reference to the frequency selection block.

| +| Physical layer clock
(e.g., Ethernet equipment clock (EEC)/synchronous digital hierarchy (SDH) equipment clock) |

Synchronizes to a physical layer frequency input or external frequency input and provides this as a frequency reference to the frequency selection block. Includes selection among various frequency inputs when more than one source is available. It would typically implement a synchronous clock as specified in [ITU-T G.8262]/[ITU-T G.813].

| + +Table B.2 describes the functionality of the interfaces depicted in Figure B.1. + +**Table B.2 – T-TSC-P and T-BC-P clock model external interfaces** + +| External interfaces label | Functionality | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Packet I/O | Interfaces to transmit and receive PTP packets from the packet processing block. On the TR side, it acts as a PTP port in the timeReceiver state to interact with external PTP timeTransmitter devices; on the TT side, it acts as a PTP port in the timeTransmitter state to interact with external PTP timeReceiver devices. | +| 1 PPS output | 1 PPS phase output ([ITU-T G.703]) generated by the time and frequency generation block. | +| ToD output | ToD serial time information output generated by the time and frequency generation block. | +| Frequency output
(e.g., 2 048 kHz) | Frequency output (e.g., [ITU-T G.703] 2 048 kHz) provides frequency information. Generated by the time and frequency generation block. (Note) | +| Physical layer frequency input
(e.g., SyncE) | Physical layer frequency input from applicable interfaces available on the clock (e.g., SyncE). Provides frequency information to the physical layer clock block. | +| Physical layer frequency output
(e.g., SyncE) | Physical layer frequency output provides frequency information on applicable interfaces available on the clock (e.g., SyncE). Generated from the physical layer clock block. | +| External frequency input
(e.g., 2 048 kHz) | External frequency input from applicable interfaces available on the clock (e.g., [ITU-T G.703] 2 048 kHz or 2 048 kbit/s). Provides frequency information to the physical layer clock block. | +| NOTE – The frequency output may be used to provide frequency to the end application described in Appendix IV.1 of [ITU-T G.8275]. The performance of the frequency output as shown in Figure IV.1 of [ITU-T G.8275], and whether it meets the required network limits (see clause 9.2.2 of [ITU-T G.8261]), are for further study. | | + +## Appendix I + +### Consideration of timeReceiver clocks embedded in end applications + +(This appendix does not form an integral part of this Recommendation.) + +A [ITU-T G.8271.2] time synchronization deployment consists of many network clocks, such as a primary reference time clock (PRTC), telecom grandmaster (T-GM), T-BC-P, other modules without timing support, T-TSC-A and TSC-P, and end application time clocks. Multiple time synchronization deployment cases are shown in Appendix I of [ITU-T G.8271.2]. In those deployment cases, an "end application time clock" is shown as providing the output clock at interface E. The requirements of these end application time clocks and the performance at interface E lie outside the scope of this Recommendation. + +When the T-TSC-A or T-TSC-P is embedded inside the end application, as shown in Appendix I of [ITU-T G.8271.2], the combination of the T-TSC-A or T-TSC-P and the end application time clock is implementation specific, where the combined performance may not behave as the stand-alone T-TSC-A or T-TSC-P described in this Recommendation. The T-TSC-A and T-TSC-P output interface D may not be available external to the equipment for measurement. + +In many end applications, there is a need to have coherent frequency and time synchronization or to generate coherent frequency and time outputs. In such cases, it is important to properly design the end application time clock to implement the coherency. + +## **Appendix II** + +### **Consideration of variable temperature testing** + +(This appendix does not form an integral part of this Recommendation.) + +For information related to variable temperature testing methodology, refer to Appendix I of [b-ITU-T G.8273]. + +For information related to variable temperature holdover testing methodology, refer to Appendix II of [b-ITU-T G.8273]. + +## Appendix III + +### Consideration of the use of a synchronous equipment clock to maintain time holdover for partial timing support networks + +(This appendix does not form an integral part of this Recommendation.) + +A partially aware equipment clock may have multiple sources of time synchronization available for selection, such as GNSS and PTP. In addition to the time synchronization sources, there may be frequency synchronization sources available to the equipment, as shown in Figure III.1. When the time synchronization source(s) are no longer available (such as signal fail), or degraded (such as poor clockClass), the equipment may enter holdover depending on the best timeTransmitter clock algorithm (BTCA) and operator configuration. During holdover, the equipment may benefit from using an external, traceable physical layer frequency reference, instead of its internal oscillator in order to achieve improved performance. This would be most applicable when the traceability information of the physical layer frequency reference indicates quality level PRC, primary reference source (PRS), PRTC or similar and the synchronous equipment clock stability available to the equipment is better than the local oscillator. A network traceable from a chain of enhanced synchronous equipment clocks (see [ITU-T G.8262.1]) is preferred over a network traceable reference from a chain of synchronous equipment clocks. + +![Diagram of a partially aware PTP clock with diverse synchronization sources.](e90987faabad6a6665cd8ed1151dc474_img.jpg) + +The diagram illustrates a 'Partially aware PTP clock (T-TSC-P, T-BC-P)' represented by a rectangular box. Inside this box, at the bottom, is a dashed rectangle labeled 'Local oscillator'. Above the clock box are two cloud-shaped nodes. The left cloud is labeled 'Partially aware PTP network' and the right cloud is labeled 'Physical layer synchronization network'. Both clouds have downward-pointing arrows leading to the top of the clock box, indicating that the clock receives synchronization signals from both networks. + +Diagram of a partially aware PTP clock with diverse synchronization sources. + +G.8273.4-Y.1368.4(20)\_FIII.1 + +**Figure III.1 – Partially aware clock with diverse synchronization sources** + +Note that in Figure III.1 the PTP time synchronization source and the physical layer frequency source are shown separately. This is simply for illustrative purposes; they may be received on the same Ethernet interface of the equipment. + +NOTE – The following can degrade the stability of a chain of synchronous equipment clocks (see [ITU-T G.8262]) or enhanced synchronous equipment clocks (see [ITU-T G.8262.1]): + +- temperature changes that affect the Ethernet cable delay and introduce wander on the synchronous equipment clock input; +- phase transients caused by physical layer synchronization network rearrangements. + +## Appendix IV + +### Use of a synchronous equipment clock to assist a PTP time lock + +(This appendix does not form an integral part of this Recommendation.) + +A partially aware equipment clock typically includes a stable local oscillator as a frequency reference to use to assist in synchronizing to incoming PTP packets. In addition to the PTP synchronization source, there may be frequency synchronization sources available to the equipment, as shown in Figure III.1. + +When the situation arises that: + +- a physical layer frequency reference is available at the input of the equipment clock; and +- the partially aware equipment clock supports the use of such an input; and +- the equipment is configured by the operator to use the physical layer reference, + +then it may be advantageous to use the externally available physical layer frequency input to assist in the stabilization of the timeReceiver clock within the equipment, rather than relying solely on the local oscillator, while locking to the PTP network reference source. This would be most applicable when the traceability information of the physical layer frequency reference indicates quality level PRC, PRS, PRTC or similar. It is assumed that an enhanced synchronous equipment clock (see [ITU-T G.8262.1]) would be used to ensure the clock meets wander generation specifications. + +## Appendix V + +### Synchronization interworking function P-F node limits + +(This appendix does not form an integral part of this Recommendation.) + +[ITU-T G.8275] specifies the concept of a synchronization interworking function (IWF), where a node is used to translate between different segments of a network that are running different PTP profiles. + +For a synchronization IWF from PTS to full timing support (FTS) (P-F) node, distributing PTP timing from a PTS profile to a FTS profile, the clock performance limits mainly consider the PTS type of network used on the TR port, regardless of the FTS used on the TT port. + +Therefore, all limits applied to the PTS clocks within the scope of this Recommendation may also apply to such a synchronization IWF P-F node, even if it is not strictly a PTS one. + +## Appendix VI + +## PTP noise tolerance testing for PTS and APTS clocks + +(This appendix does not form an integral part of this Recommendation.) + +The PTP noise tolerance of a PTS or APTS clock is defined as the network limit at reference point C in [ITU-T G.8271.2] (see clauses 7.3 and 8.3). This appendix describes how to generate suitable test signals to check conformance with this requirement. This is based on a similar method used in [b-ITU-T G.8263] for testing of the PEC-S-F. + +### VI.1 Testing set-up for PTP noise tolerance testing + +The general testing set-up for PTP noise tolerance testing of a PTS Clock (T-TSC-P or T-BC-P) is shown in Figure VI.1. + +![Figure VI.1: PTP noise tolerance testing of a PTS clock (T-TSC-P or T-BC-P). The diagram shows a 'Time reference' connected to a 'PTP GM' and a 'Time error measurement' block. The 'PTP GM' is connected to a 'Bi-directional packet delay generator' which is influenced by a 'Statistical PVD model'. The 'Bi-directional packet delay generator' is connected to the 'Device under test' (PTS clock under test) via 'PTP over Ethernet'. The 'Device under test' has a 'Time input port' and a 'Time output port'. The 'Time output port' is connected to the 'Time error measurement' block via '1 PPS/ToD or PTP over Ethernet'. The 'Time error measurement' block is also connected to a 'Data log'. The diagram is divided into 'Test equipment' and 'Device under test' by a dashed line.](6470d350326789d5306eabcb76533951_img.jpg) + +``` +graph LR + TR[Time reference] --> PTPGM[PTP GM] + TR --> TEM[Time error measurement] + PTPGM <--> BPDG[Bi-directional packet delay generator] + SPM[Statistical PVD model] --> BPDG + BPDG -- "PTP over Ethernet" --> DUT[PTS clock under test] + DUT -- "1 PPS/ToD or PTP over Ethernet" --> TEM + TEM --> DL[Data log] + subgraph Test equipment + TR + PTPGM + BPDG + SPM + TEM + DL + end + subgraph Device under test + DUT + end +``` + +Figure VI.1: PTP noise tolerance testing of a PTS clock (T-TSC-P or T-BC-P). The diagram shows a 'Time reference' connected to a 'PTP GM' and a 'Time error measurement' block. The 'PTP GM' is connected to a 'Bi-directional packet delay generator' which is influenced by a 'Statistical PVD model'. The 'Bi-directional packet delay generator' is connected to the 'Device under test' (PTS clock under test) via 'PTP over Ethernet'. The 'Device under test' has a 'Time input port' and a 'Time output port'. The 'Time output port' is connected to the 'Time error measurement' block via '1 PPS/ToD or PTP over Ethernet'. The 'Time error measurement' block is also connected to a 'Data log'. The diagram is divided into 'Test equipment' and 'Device under test' by a dashed line. + +G.8273.4(24) + +Figure VI.1 – PTP noise tolerance testing of a PTS clock (T-TSC-P or T-BC-P) + +The PTP GM and the time error measurement block are both timed from the same time reference. + +The delay sequences are generated by means of a statistical model, with the parameters chosen to generate a delay distribution with properties similar to the network limits defined in [ITU-T G.8271.2]. + +The output from the clock under test is either a 1 PPS/ToD (for a T-TSC-A or T-TSC-P) or PTP over Ethernet (for a T-BC-A or T-BC-P). + +When testing an APTS clock (T-TSC-A or T-BC-A), a local time reference is also required. This could be a GNSS simulator generating a GNSS RF signal, or a 1 PPS/ToD or PTP time signal generator. The local time reference should be locked to the central time reference. This is shown in Figure VI.2. + +The initial condition is for the APTS clock under test to use this local time reference as its primary input, and then to switch to the PTP input on failure of the local time reference. This is simulated by squelching the output signal of the local time reference. + +![Figure VI.2 – PTP noise tolerance testing of an APTS clock (T-TSC-A or T-BC-A). The diagram shows a 'Time reference' clock connected to a 'PTP GM' block. The 'PTP GM' is connected to a 'Bi-directional packet delay generator' block. A 'Statistical PVD model' block is connected to the 'Bi-directional packet delay generator'. The 'Bi-directional packet delay generator' is connected to an 'APTS clock under test' block via a 'PTP over Ethernet' link. The 'APTS clock under test' is also connected to a 'Local time reference' block via a 'GNSS RF, 1 PPS/ToD or PTP over Ethernet' link. The 'APTS clock under test' has a 'Time output port' connected to a 'Time error measurement' block. The 'Time error measurement' block is connected to a 'Data log' block. The 'Time error measurement' block is also connected to the 'PTP GM' block via a '1 PPS/ToD or PTP over Ethernet' link. The diagram is divided into two sections: 'Test equipment' on the left and 'Device under test' on the right, separated by a dashed line. The reference G.8273.4(24) is noted at the bottom right.](c494cd874a082a97b50b3c4d3938f467_img.jpg) + +Figure VI.2 – PTP noise tolerance testing of an APTS clock (T-TSC-A or T-BC-A). The diagram shows a 'Time reference' clock connected to a 'PTP GM' block. The 'PTP GM' is connected to a 'Bi-directional packet delay generator' block. A 'Statistical PVD model' block is connected to the 'Bi-directional packet delay generator'. The 'Bi-directional packet delay generator' is connected to an 'APTS clock under test' block via a 'PTP over Ethernet' link. The 'APTS clock under test' is also connected to a 'Local time reference' block via a 'GNSS RF, 1 PPS/ToD or PTP over Ethernet' link. The 'APTS clock under test' has a 'Time output port' connected to a 'Time error measurement' block. The 'Time error measurement' block is connected to a 'Data log' block. The 'Time error measurement' block is also connected to the 'PTP GM' block via a '1 PPS/ToD or PTP over Ethernet' link. The diagram is divided into two sections: 'Test equipment' on the left and 'Device under test' on the right, separated by a dashed line. The reference G.8273.4(24) is noted at the bottom right. + +**Figure VI.2 – PTP noise tolerance testing of an APTS clock (T-TSC-A or T-BC-A)** + +The test procedure is to be carried out under constant temperature conditions (within $\pm 1\text{K}$ ). Any stress testing under a noisy thermal environment is for further study. + +### VI.2 Statistical PDV model + +The packet delay sequences used in this method are based on a simple statistical model for a network experiencing bursty traffic. This is similar to the first method described in Appendix I of [b-ITU-T G.8263]. + +Studies of Internet traffic ([b-Leland], [b-Sahinoglu]) have shown that the traffic distribution is bursty at many different scales, and that this self-similar behaviour can be modelled by using flicker noise to represent the traffic load. + +Additionally, it can be shown that the queuing action of a packet switch or router imposes a gamma ( $\Gamma$ ) distribution1 on the probability density function of the delays through the switch or router. The $\alpha$ (or shape) parameter of the $\Gamma$ distribution varies with the traffic load. + +The resulting statistical model is shown schematically in Figure VI.3. + +1 The probability density function of a gamma distribution is controlled by two parameters, $\alpha$ (or "shape") and $\beta$ (or "scale"). It is described by the equation $f(x; \alpha, \beta) = \frac{\beta^\alpha x^{\alpha-1} e^{-\beta x}}{\Gamma(\alpha)}$ , for $x, \alpha$ and $\beta > 0$ , and where the gamma function, $\Gamma(\alpha) = (\alpha - 1)!$ + +![Figure VI.3: Statistical model of packet delay variation for timing packets. The diagram shows a flow from a 'PTP GM' to a 'Receiving clock'. The 'PTP GM' sends 'Regularly spaced timing packets'. These packets pass through a central oval labeled 'Gamma distribution, with shape controlled by traffic load (represents the effect of a switched packet network)'. Above this oval, a large downward arrow labeled 'Traffic load' and 'Self-similar variation, modelled by flicker noise' points to the oval. The output from the oval to the 'Receiving clock' is labeled 'Timing packets with flicker noise spacing, and Gamma distribution'. A small reference code 'G.8273.4-Y.1368.4(20)-Amd.1(21)_FVI.3' is at the bottom right.](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +Figure VI.3: Statistical model of packet delay variation for timing packets. The diagram shows a flow from a 'PTP GM' to a 'Receiving clock'. The 'PTP GM' sends 'Regularly spaced timing packets'. These packets pass through a central oval labeled 'Gamma distribution, with shape controlled by traffic load (represents the effect of a switched packet network)'. Above this oval, a large downward arrow labeled 'Traffic load' and 'Self-similar variation, modelled by flicker noise' points to the oval. The output from the oval to the 'Receiving clock' is labeled 'Timing packets with flicker noise spacing, and Gamma distribution'. A small reference code 'G.8273.4-Y.1368.4(20)-Amd.1(21)\_FVI.3' is at the bottom right. + +**Figure VI.3 – Statistical model of packet delay variation for timing packets** + +It does not include the potential transients that can occur in packet networks, such as floor delay steps. In addition, it may not model accurately a network that has significant non-bursty traffic (e.g., constant bit rate (CBR) traffic). + +This method is therefore considered suitable as a minimum test for characterizing the noise tolerance of a packet timeReceiver clock. Additional testing is recommended to ensure that the packet timeReceiver clock will tolerate more complex network situations with transients. + +### VI.3 Parameters for the PDV model + +In this model, the individual values of the distribution represent packet delays in the network and are in units of time. The $\alpha$ parameter describing the shape of the $\Gamma$ - distribution is controlled by a flicker noise sequence representing the traffic load. This is adjusted once per second. The $\beta$ (or scale) parameter is chosen to give a reasonable spread of packet delays and has the units of inverse time. When using microseconds as the time unit, a $\beta$ value of $20 \mu\text{s}^{-1}$ yields a range of values of approximately $300 \mu\text{s}$ , as shown in Figure VI.4. + +The range of variation of the $\alpha$ parameter is chosen to give a probability of 0.25% that a delay value will be within $1.1 \mu\text{s}$ of the minimum delay. Figure VI.5 shows the cumulative density function at 0.25% starts to exceed $1.1 \mu\text{s}$ at an $\alpha$ value of just under 2. However, the mean $\alpha$ value would have to remain above 2 for the entire 200 s window for the mean delay of the selected percentile to be above $1.1 \mu\text{s}$ . In addition, this represents only one direction of packet flow. The probability of both the forward and reverse directions lining up to produce a $\text{pktSelected2WayTE}$ of $1.1 \mu\text{s}$ is quite small. Empirically, a range of 0 to 4 has been found to be suitable for the $\alpha$ parameter. + +The same model is adopted to generate the delays for both *sync* and *delay\_req* packets, but with independent random variables for each. + +![Figure VI.4: Probability density function of gamma distributions with β value of 20 for varying α values. The graph shows multiple curves for α values from 0.25 to 3. The x-axis is 'Delay, μs' from 0 to 300, and the y-axis is 'Probability' from 0 to 0.04. A legend at the bottom lists the α values: 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3. A small text 'G.8273.4-Y.1368.4(20)-Amd.1(21)_FVI.4' is in the bottom right corner.](d68ecc44f3cfaed866a846f9fa4bdf38_img.jpg) + +Figure VI.4: Probability density function of gamma distributions with β value of 20 for varying α values. The graph shows multiple curves for α values from 0.25 to 3. The x-axis is 'Delay, μs' from 0 to 300, and the y-axis is 'Probability' from 0 to 0.04. A legend at the bottom lists the α values: 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3. A small text 'G.8273.4-Y.1368.4(20)-Amd.1(21)\_FVI.4' is in the bottom right corner. + +**Figure VI.4 – Probability density function of gamma distributions with $\beta$ value of 20 for varying $\alpha$ values** + +![Figure VI.5: Cumulative density function of gamma distributions with β value of 20 and varying α parameters. The graph shows multiple curves for α values from 0.25 to 3. The x-axis is 'Delay, μs' from 0 to 2, and the y-axis is 'Cumulative density' from 0 to 0.02. A vertical red dashed line at 1.1 μs and a horizontal red dashed line at 0.0025 (0.25%) intersect at the α = 1.5 curve. Other curves are labeled α = 1.75 and α = 2. A legend at the bottom lists the α values: 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3. A small text 'G.8273.4-Y.1368.4(20)-Amd.1(21)_FVI.5' is in the bottom right corner.](a844248c1fa0a79f187fc9aa111182f7_img.jpg) + +Figure VI.5: Cumulative density function of gamma distributions with β value of 20 and varying α parameters. The graph shows multiple curves for α values from 0.25 to 3. The x-axis is 'Delay, μs' from 0 to 2, and the y-axis is 'Cumulative density' from 0 to 0.02. A vertical red dashed line at 1.1 μs and a horizontal red dashed line at 0.0025 (0.25%) intersect at the α = 1.5 curve. Other curves are labeled α = 1.75 and α = 2. A legend at the bottom lists the α values: 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3. A small text 'G.8273.4-Y.1368.4(20)-Amd.1(21)\_FVI.5' is in the bottom right corner. + +**Figure VI.5 – Cumulative density function of gamma distributions with $\beta$ value of 20 and varying $\alpha$ parameters** + +### VI.4 Different requirements for APTS and PTS models + +While there are several similar requirements to the patterns for APTS and PTS clocks, allowing the same basic statistical model to be used, there are also some differences. + +Common requirements from [ITU-T G.8271.2]: + +- Metric: pktSelected2WayTE + +- Selection method: percentile average packet selection +- Selection window: 200 s +- Selection Percentage: 0.25% +- Window step size: 20 s + +Specific requirements for APTS: + +- Peak-to-peak $\text{pktSelected2WayTE} \leq 1100 \text{ ns}$ +- $|\text{cTE}|$ should be much higher than 1100 ns (this is not mentioned in [ITU-T G.8271.2], and part of the capability of the APTS clocks should be to tolerate the cTE created by network asymmetry. Therefore, any test pattern should have a large asymmetry to verify the compensation accuracy). + +Specific requirements for PTS: + +- $\text{Max}|\text{pktSelected2WayTE}| \leq 1100 \text{ ns}$ +- $|\text{cTE}|$ should be much smaller than 1100 ns. + +#### VI.4.1 APTS pattern generation + +The set of PDV patterns for use in testing APTS clocks may be generated in the following way: + +- 1) Two independent sets of delays are generated for the *sync* and *delay\_req* packets using the method described above. The $\alpha$ and $\beta$ values for the gamma distribution are chosen to give the required profile of packet delays. +- 2) An arbitrary fixed delay (e.g., 100 $\mu\text{s}$ ) is added to both sets of packet delays, representing the minimum packet delay through the network. +- 3) An additional "asymmetry" delay is added to one set of patterns. This is chosen to be much larger than the required maximum time error, to verify the clock's ability to compensate for it. For example, 20 $\mu\text{s}$ is a suitable value, resulting in a cTE of 10 $\mu\text{s}$ . + +#### VI.4.2 PTS pattern generation + +The set of PDV patterns for use in testing PTS clocks may be generated in the following way: + +- 1) Two independent sets of delays are generated for the *sync* and *delay\_req* packets using the method described above. +- 2) An arbitrary fixed delay (e.g., 100 $\mu\text{s}$ ) is added to both sets of packet delays, representing the minimum packet delay through the network. +- 3) An additional "asymmetry" delay is added to one set of patterns. This is chosen to be smaller than the required maximum time error, to keep the overall time error within $\pm 1.1 \mu\text{s}$ . For example, 1 $\mu\text{s}$ is a suitable value, resulting in a cTE of 500 ns. + +As for the APTS patterns, the $\alpha$ and $\beta$ values, the fixed delay and asymmetry may be adjusted to generate a pattern with the required characteristics. + +### VI.5 Example delay patterns + +The following figures show an example set of patterns generated for APTS using the method described. This particular example was generated at 32 packets/s, using a range of $\alpha$ values between 0 and 3, a $\beta$ value of $20 \mu\text{s}^{-1}$ , together with a fixed delay of 100 $\mu\text{s}$ and an asymmetry of 24 $\mu\text{s}$ . + +Figure VI.6 shows the *sync* delays generated using these parameters. A clear floor or minimum delay is seen at 112 $\mu\text{s}$ . The corresponding plot for *delay\_req* packets in Figure VI.7 also has a clear floor delay, but at 88 $\mu\text{s}$ , demonstrating the 24 $\mu\text{s}$ asymmetry between the two delay distributions. Both distributions have a range of delays of just over 300 $\mu\text{s}$ . + +![Scatter plot showing Sync packet delay variation over time. The y-axis is 'Delay, us' from 0 to 450 in increments of 50. The x-axis is 'Time, s' from 0 to 32400 in increments of 900. The plot shows a dense cloud of blue points with a floor around 110 us and outliers up to 420 us. A legend at the bottom center indicates blue dots represent 'Sync Delay'.](24b549c0c4b79c515b244625cf4f4978_img.jpg) + +Scatter plot showing Sync packet delay variation over time. The y-axis is 'Delay, us' from 0 to 450 in increments of 50. The x-axis is 'Time, s' from 0 to 32400 in increments of 900. The plot shows a dense cloud of blue points with a floor around 110 us and outliers up to 420 us. A legend at the bottom center indicates blue dots represent 'Sync Delay'. + +**Figure VI.6 – Sync packet delay variation** + +![Scatter plot showing Delay_req packet delay variation over time. The y-axis is 'Delay, us' from 0 to 450 in increments of 50. The x-axis is 'Time, s' from 0 to 32400 in increments of 900. The plot shows a dense cloud of green points with a floor around 90 us and outliers up to 400 us. A legend at the bottom center indicates green dots represent 'Delay Req'.](03498c9b76f980b32f2dfbb7c2e539d2_img.jpg) + +Scatter plot showing Delay\_req packet delay variation over time. The y-axis is 'Delay, us' from 0 to 450 in increments of 50. The x-axis is 'Time, s' from 0 to 32400 in increments of 900. The plot shows a dense cloud of green points with a floor around 90 us and outliers up to 400 us. A legend at the bottom center indicates green dots represent 'Delay Req'. + +**Figure VI.7 – Delay\_req packet delay variation** + +Figure VI.8 zooms in on the floor of the sync packet distribution, showing how the thickness of the floor varies with $\alpha$ . This is what should be expected for real traffic with an increase in traffic load. + +The floor thickness is calculated by averaging the delays of the fastest 0.25% of packets in each 200 s window. This is shown in Figure VI.9. It can be observed that the peak-to-peak value of this is about 1.3 $\mu\text{s}$ , which is higher than the network limit for APTS of 1.1 $\mu\text{s}$ . However, the network limit applies + +to the two-way combination of forward and reverse delays, and it is unlikely that the "worst case" delays will line up exactly in each set of packet delays. + +![Figure VI.8: A dual-axis plot showing 'Delay, us' on the left Y-axis (110 to 116) and 'Alpha' on the right Y-axis (0 to 10.5) against 'Time, s' (0 to 32400). The plot contains two data series: 'Sync Delay' represented by blue dots and 'Alpha (Sync)' represented by a black line. The Sync Delay dots are densely packed between 112 and 116 us, while the Alpha (Sync) line fluctuates between approximately 1.5 and 3.0.](c9bbd160a32f2fdbd7a819d382ac49b6_img.jpg) + +Figure VI.8: A dual-axis plot showing 'Delay, us' on the left Y-axis (110 to 116) and 'Alpha' on the right Y-axis (0 to 10.5) against 'Time, s' (0 to 32400). The plot contains two data series: 'Sync Delay' represented by blue dots and 'Alpha (Sync)' represented by a black line. The Sync Delay dots are densely packed between 112 and 116 us, while the Alpha (Sync) line fluctuates between approximately 1.5 and 3.0. + +**Figure VI.8 – Zoom-in on the floor delay variation for sync packets and $\alpha$ parameter** + +![Figure VI.9: A line plot showing 'pktSelected1WayDelay, Sync, us' on the Y-axis (111.8 to 113.4) against 'Time, s' (0 to 32400). The plot contains a single data series: 'Sync messages' represented by a blue line. The line shows significant fluctuations, with peaks reaching up to 113.2 us and troughs down to 112.0 us.](c53adc66eab40abd5f8b9107d950ad04_img.jpg) + +Figure VI.9: A line plot showing 'pktSelected1WayDelay, Sync, us' on the Y-axis (111.8 to 113.4) against 'Time, s' (0 to 32400). The plot contains a single data series: 'Sync messages' represented by a blue line. The line shows significant fluctuations, with peaks reaching up to 113.2 us and troughs down to 112.0 us. + +**Figure VI.9 – Average delay of selected sync packets** + +Figures VI.10 and VI.11 show the same plots, but for the delay\_req packets. The $\alpha$ sequence is independently generated from that for the sync packets, therefore there is no correlation between sync and delay\_req packet delays. + +![Figure VI.10: Dual-axis plot of Delay and Alpha over Time. Left Y-axis: Delay, us (86-92). Right Y-axis: Alpha (0-10.5). X-axis: Time, s (0-32400). Green dots represent Delay Req; black line represents Alpha (D_Req).](f24d06b5e3b1d8ae12d4893e7619f6f5_img.jpg) + +This figure is a dual-axis plot. The left Y-axis represents 'Delay, us' ranging from 86 to 92. The right Y-axis represents 'Alpha' ranging from 0 to 10.5. The X-axis represents 'Time, s' ranging from 0 to 32400. The plot contains two data series: 'Delay Req', represented by green dots clustered between 88 and 92 us; and 'Alpha (D\_Req)', represented by a black line fluctuating between approximately 0.5 and 3.0 on the Alpha scale. + +Figure VI.10: Dual-axis plot of Delay and Alpha over Time. Left Y-axis: Delay, us (86-92). Right Y-axis: Alpha (0-10.5). X-axis: Time, s (0-32400). Green dots represent Delay Req; black line represents Alpha (D\_Req). + +**Figure VI.10 – Zoom-in on the floor delay variation for delay\_req packets, with $\alpha$ parameter** + +![Figure VI.11: Line plot of pktSelected1WayDelay over Time. Y-axis: pktSelected1WayDelay, Delay_req, us (87.8-89.4). X-axis: Time, s (0-32400). Green line represents Delay_req messages.](65a73373b57df71e5c2ce1ce0eb7b65d_img.jpg) + +This figure is a line plot. The Y-axis represents 'pktSelected1WayDelay, Delay\_req, us' ranging from 87.8 to 89.4. The X-axis represents 'Time, s' ranging from 0 to 32400. The plot contains a single data series: 'Delay\_req messages', represented by a green line that fluctuates between approximately 88.0 and 89.2 us. + +Figure VI.11: Line plot of pktSelected1WayDelay over Time. Y-axis: pktSelected1WayDelay, Delay\_req, us (87.8-89.4). X-axis: Time, s (0-32400). Green line represents Delay\_req messages. + +**Figure VI.11 – Average delay of selected delay\_req packets** + +Finally, Figure VI.12 shows the pktSelected2WayTE measured from two the sets of packet delays. The peak-to-peak value of the pktSelected2WayTE is 1.1 $\mu\text{s}$ , with a mean value (cTE) of $-12 \mu\text{s}$ . + +![Figure VI.12: A line graph showing the packet selected two-way time error (pktSelected2WayTE) in microseconds (us) over time in seconds (s). The y-axis ranges from -12.8 to -11.2 us with major grid lines every 0.2 us. The x-axis ranges from 0 to 32400 s with major grid lines every 3600 s. The plot shows a highly fluctuating signal, with peaks reaching approximately -11.4 us and troughs reaching approximately -12.7 us. A legend at the bottom indicates the line represents 'pktSelected2WayTE'.](f899c67120dc04a5e5a5c2d94461a077_img.jpg) + +Figure VI.12: A line graph showing the packet selected two-way time error (pktSelected2WayTE) in microseconds (us) over time in seconds (s). The y-axis ranges from -12.8 to -11.2 us with major grid lines every 0.2 us. The x-axis ranges from 0 to 32400 s with major grid lines every 3600 s. The plot shows a highly fluctuating signal, with peaks reaching approximately -11.4 us and troughs reaching approximately -12.7 us. A legend at the bottom indicates the line represents 'pktSelected2WayTE'. + +**Figure VI.12 – pktSelected2WayTE** + +Similar patterns can be generated for PTS clocks, adjusting the asymmetry value and $\alpha$ values to generate the desired peak-to-peak range while keeping the $\max|\text{pktSelected2WayTE}|$ within the 1.1 $\mu\text{s}$ network limit. + +### VI.6 Output requirements + +The required behaviour of a clock in the presence of noise up to the network limit at its input is described in clauses 7.3 and 8.3. + +In particular the clock should: + +- not generate any alarms, +- not switch references, +- not go into holdover. + +In addition, the $\max|\text{TE}_L|$ of the clock output should remain within the limits defined at reference point D in [ITU-T G.8271.2]. This requirement is only applicable in case of T-TSC-A or T-TSC-P external to the end application. Therefore, in the case of a T-TSC-A or T-TSC-P integrated within an end application, this reference point may not always be accessible. + +## Appendix VII + +### Analysis of conversion of network limits to equipment specification for APTS + +(This appendix does not form an integral part of this Recommendation.) + +This appendix shows some of the background calculations that were used to develop the requirements in clause 7 of this Recommendation based on the [ITU-T G.8271.2] network limits for APTS deployment. + +The following network limits we already known as input for the equipment noise: + +- Limit C, PTP input from [ITU-T G.8271.2]. +- Limit L, local time reference input from [ITU-T G.8271.2]. +- Limit D, TE at output towards end application from [ITU-T G.8271.2]. + +The equipment noise requirement was developed based on the following: the total noise of the equipment, when combined with the noise existing at the equipment input (network limit at either reference point C or L of [ITU-T G.8271.2]), must be less than the network limit at reference point D of [ITU-T G.8271.2]. + +### VII.1 Total noise budget between network limits + +Table VII.1 covers the following two different APTS scenarios: + +- APTS with time/phase holdover based on PTP after loss of local time reference. +- APTP with time/phase holdover based on oscillator after loss of local time reference. + +**Table VII.1 – APTS budget analysis (Class B equipment clock)** + +| Allocation | Reference | APTS with holdover based on PTP (ns) | APTS with holdover based on Oscillator (ns) | +|-------------------------------------------------------------------------------|------------------------------------------------|--------------------------------------|---------------------------------------------| +| Input point C | Clause 7.3 of [ITU-T G.8271.2] | 1100 | N/A (Note 1) | +| Local time reference point L | Clause 7.1 of [ITU-T G.8271.2] | 100 | 100 | +| Noise generation cTE | Clause 7.2.2 [ITU-T G.8273.4] | 20 (Note 4) | 20 (Note 4) | +| Dynamic noise budget from combining LTR input noise with noise generation dTE | [ITU-T G.8271.2] and [ITU-T G.8273.4] (Note 3) | 10 (Note 3) | 10 (Note 3) | +| Noise transfer | Clause 7.4 of [ITU-T G.8273.4] | 5 (Note 5) | 5 (Note 5) | +| Holdover | None (Note 2) | 93 (Note 2) | 1193 (Note 1) | +| Transients and switching | Clause 7.5 of [ITU-T G.8273.4] | 22 | 22 | + +**Table VII.1 – APTS budget analysis (Class B equipment clock)** + +| Allocation | Reference | APTS with holdover based on PTP (ns) | APTS with holdover based on Oscillator (ns) | +|-----------------------|--------------------------------|--------------------------------------|---------------------------------------------| +| Output point D | [ITU-T G.8271.2]
Clause 7.4 | 1350 | 1350 | + +NOTE 1 – Holdover is based on local oscillator. In this case, the network PDV at network limit C is not applicable (as the PTP input is unused). Therefore, the 1100 ns noise budget of network limit C may be allocated to holdover of the equipment clock. + +NOTE 2 – Holdover is based on synchronization to a backup PTP source. See Table VII.2 for breakdown of the sub-components. As detailed in Appendix VII.2, this value is the remaining noise budget after all other components and limits were considered. + +NOTE 3 – This value represents the additive dTE noise when the equipment clock is locked to the local time reference, which means that it is not the noise generation of the equipment. This is the increase in noise after computing the RSS of the input noise and noise generation; meaning it is the RSS (input noise and noise generation) minus input noise, or stated differently, the output noise minus the input noise. See Appendix VII.4 for more details. + +NOTE 4 – The analysis in this appendix shows the Class B equipment clock (with cTE of 20 ns). The same analysis may be performed with Class A equipment clock (with cTE of 50 ns). In the case of Class A, the holdover budget is reduced by 30 ns. + +NOTE 5 – Noise gain of 0.1 dB on LTR at point L with 100 ns pk-pk amplitude is about 1 ns (table rounds up to 5 ns). + +### VII.2 Holdover operation + +In Table VII.1 there is a value assigned to holdover (based on PTP or local oscillator). The holdover value does not represent the holdover performance requirements of the equipment. The holdover value represents the amount of error that may accumulate while the equipment is in holdover, while still meeting the network limit at reference point D of [ITU-T G.8271.2]. The holdover value was not selected, but instead was the remainder of the noise error allowed after the noise tolerance, noise transfer, noise generation and switching events were analysed. Therefore, there is no special significance to the holdover value that appears in Table VII.1. + +In Table VII.1, when the holdover is based on PTP, the analysis was done for noise of each sub-components as shown in Table VII.2. In this case, the model is that the PTP clock (that maintains holdover by synchronizing to the PTP packets) will have noise generation (from local oscillator) and noise transfer (phase gain peaking from the input PTP noise) components. + +**Table VII.2 – APTS budget analysis for PTP holdover use (Class B equipment clock)** + +| Component | Holdover based on PTP (ns)
(Note 1) | +|--------------------------------------------------------------------------------------|----------------------------------------| +| Noise generation cTE | 0 | +| Dynamic noise budget from combining PTP input noise with noise generation dTE | 78
(Note 2, 3) | +| Noise transfer | 15
(Note 4) | +| Total | 93 | + +**Table VII.2 – APTS budget analysis for PTP holdover use (Class B equipment clock)** + +| Component | Holdover based on PTP (ns)
(Note 1) | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------| +|

NOTE 1 – The values in this table are not reflected in the equipment clock specification as individual components, as the requirements when locked to PTP falls under holdover requirements (see clause 7.6.2).

NOTE 2 – This value represents the additive dTE noise when the equipment clock is locked to the PTP input, which means that it is not the noise generation of the equipment. This is the increase in noise after computing the RSS of the input noise and noise generation; in other words, it is the RSS (input noise and noise generation) minus input noise, or stated differently, the output noise minus the input noise.

NOTE 3 – The noise generation dTE was the larger of the expected increase in noise after following RSS computation (combining the input PDV noise and the local noise generation), and the remainder of the noise error allowed to reach the total holdover budget of 93 ns. Therefore, the value is larger than expected based only on RSS computation analysis.

NOTE 4 – Noise gain of 0.1 dB on PTP input at point C with 1100 ns pk-pk amplitude is about 13 ns (table rounds up to 15 ns).

| | + +### VII.3 Transient operation and switching + +Figure VII.1 illustrates a representation of holdover and transient (switching) operation. It is intended to show the combined value for the entire operation of loss of reference to restoration of reference, and individual sub-stages that an implementation may follow. + +![Figure VII.1 – Transients operation and switching budgeting. A graph showing Time error (ns) on the y-axis versus Time on the x-axis. The graph illustrates the clock's behavior during a loss and restoration of the LTR (Local Time Reference). The clock starts locked to the LTR, then enters holdover when the LTR is lost, generating a first transient. It then transitions to the PTP reference, generating a second transient. Finally, the LTR returns and is selected, returning the clock to a locked state. The overall magnitude of the time error includes switching transients, residual PTP cTE, PTP noise transfer (gain), and PTP noise generation.](c243c5b8a0de8f022cf67248c54b32bc_img.jpg) + +The clock is locked to the PTP input. There is noise generation from the PTP clock (both dTE and cTE). Referred to as holdover for APTS equipment clock operation + +The clock is in holdover (relying on local XO) waiting for new selection of input + +Locked to the LTR + +Locked to the LTR + +Time error (ns) + +Time + +Overall magnitude includes: Switching transient and residual PTP cTE, PTP noise transfer (gain), PTP noise generation + +LTR is lost, clock goes into holdover and may generate a first transient + +The clock selects the PTP reference, transitions from holdover to lock, and may generate a second transient + +The LTR returns (is restored) and is selected by the equipment clock + +G.8273.4-Y.1368.4(20)-Amd.2(22)\_FVII.1 + +Figure VII.1 – Transients operation and switching budgeting. A graph showing Time error (ns) on the y-axis versus Time on the x-axis. The graph illustrates the clock's behavior during a loss and restoration of the LTR (Local Time Reference). The clock starts locked to the LTR, then enters holdover when the LTR is lost, generating a first transient. It then transitions to the PTP reference, generating a second transient. Finally, the LTR returns and is selected, returning the clock to a locked state. The overall magnitude of the time error includes switching transients, residual PTP cTE, PTP noise transfer (gain), and PTP noise generation. + +**Figure VII.1 – Transients operation and switching budgeting** + +### VII.4 Dynamic noise accumulation for APTS + +In the dynamic noise analysis, the following assumptions were used: + +- Dynamic noise (dTE) may be analysed using a root-sum-square (RSS) approach +- The dynamic noise is centreed around the constant time error +- The cTE portion of the local time reference noise at reference point L of [ITU-T G.8271.2] is a maximum of 74 ns (of the 100 ns limit). + +A maximum value for cTE was used to take into consideration that constant noise adds linearly whereas dynamic noise adds with RSS. If a larger portion of the noise is considered to be cTE, then there is less benefit to the RSS dynamic noise accumulation, which reduces the budget of the equipment for dynamic noise wander generation, which in turn increases the complexity of the equipment design (for example a more stable oscillator may be needed). Note that the limit at the reference point L of [ITU-T G.8271.2] is not currently specified or sub-divided between dTE and cTE in [ITU-T G.8271.2]. + +In Table VII.3, the worst-case assumption of 100 ns is taken for the limit at the reference point L of [ITU-T G.8271.2], with worst-case maximum value of cTE of 74 ns, leaving 52 ns for dTE (when the noise is centred). + +**Table VII.3 – APTS dynamic noise key values** + +| Limit L dTE | Dynamic time error low-pass filtered noise generation (dTE L ) | +|-------------|---------------------------------------------------------------------------| +| 52 ns | 50 ns | + +Note that the values in Table VII.4 are peak-peak values of dynamic noise. + +From Table VII.3, the combined noise using RSS can be computed. + +- $\text{SQRT}(52^2 + 50^2)/2 + 74 = 110 \text{ ns}$ + +This 110 ns dynamic noise for the worst-case assumption matches the maximum budget from Table VII.1 related to local time reference L of [ITU-T G.8271.2] and Noise generation dTE. + +- $100 \text{ ns} + 10 \text{ ns} = 110 \text{ ns}$ + +## Appendix VIII + +## Analysis of conversion of network limits to equipment specification for PTS + +(This appendix does not form an integral part of this Recommendation.) + +This appendix shows some of the background calculations that were used to develop the requirements in clause 8 of this Recommendation based on the [ITU-T G.8271.2] network limits for PTS deployment. + +The following network limits we already known as input for the equipment noise: + +- Network limits at reference point C of [ITU-T G.8271.2], PTP input. +- Network limits at reference point D of [ITU-T G.8271.2], TE at output towards end application. + +The equipment noise requirements were developed based on the following: the total noise of the equipment, when combined with the noise existing at the equipment input (network limit at reference point C of [ITU-T G.8271.2]), must be less than the network limit at reference point D of [ITU-T G.8271.2]. + +### VIII.1 Total noise between network limit C and network limit D + +Table VIII.1 covers two different PTS scenarios: + +- PTP with phase/time holdover based on oscillator after loss of local time reference. +- PTS with phase/time holdover based on frequency layer frequency assistance after loss of local time reference. + +**Table VIII.1 – PTS budget analysis (Class B equipment clock)** + +| Allocation | Reference | PTS with holdover based on Oscillator | PTS with holdover based on SEC | +|--------------------------------------------------------------------------------------|-----------------------------------------------|---------------------------------------|--------------------------------| +| Input point C | Clause 7.3 of [ITU-T G.8271.2] | 1100 | 1100 | +| Local time reference point L | Clause 7.1 of [ITU-T G.8271.2] | N/A | N/A | +| Noise generation cTE | Clause 8.2.2 of [ITU-T G.8273.4] | 20
(Note 3) | 20
(Note 3) | +| Dynamic noise budget from combining PTP input noise with noise generation dTE | [ITU-T G.8271.2 and [ITU-T G.8273.4] (Note 1) | 48
(Note 1) | 48
(Note 1) | +| Noise transfer | Clause 8.4 of [ITU-T G.8273.4] | 30
(Note 4) | 30
(Note 4) | +| Holdover | None
(Note 2) | 130
(Note 2) | 130
(Note 2) | +| Transients and switching | Clause 8.5.1 of [ITU-T G.8273.4] | 22 | 22 | +| Output point D | | 1350 | 1350 | + +**Table VIII.1 – PTS budget analysis (Class B equipment clock)** + +| Allocation | Reference | PTS with holdover based on Oscillator | PTS with holdover based on SEC | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|---------------------------------------|--------------------------------| +|

NOTE 1 – This value represents the additive dTE noise when the equipment clock is locked to PTP, which means that it is not the noise generation of the equipment. This is the increase in noise after computing the RSS of the input noise and noise generation; meaning it is the RSS (input noise and noise generation) minus input noise, or stated differently, the output noise minus the input noise. See Appendix VIII.4 for more details.

NOTE 2 – As detailed in Appendix VIII.2, this value is the remaining noise budget after all other components and limits were considered.

NOTE 3 – The analysis in this appendix shows the Class B equipment clock (with cTE of 20 ns). The same analysis may be performed with Class A equipment clock (with cTE of 50 ns). In the case of Class A, the holdover budget is reduced by 30 ns.

NOTE 4 – Noise gain of 0.1 dB on PTP input at point C with 2200 ns pk-pk amplitude is about 26 ns (table rounds up to 30 ns).

| | | | + +### VIII.2 Holdover operation + +In Table VIII.1 there is a value assigned to holdover (based on SyncE or local oscillator). The holdover value does not represent the holdover performance requirements of the equipment. The holdover value represents the amount of error that may accumulate while the equipment is in holdover, while still meeting the network limit at reference point D of [G.8271.2]. The holdover value was not selected, but instead was the remainder of the noise error allowed after the noise tolerance, noise transfer, noise generation and switching events were analysed. Therefore, there is no special significance to the holdover value that appears in Table VIII.1. + +### VIII.3 Transient operation and switching + +Figure VIII.1 shows a representation of holdover and transient (switching) operation. It is intended to show the combined value for the entire operation of loss of reference to restoration of reference, and individual sub-stages that an implementation may follow. + +![Figure VIII.1 – Transients operation and switching budgeting. A graph showing Time error (ns) on the y-axis versus Time on the x-axis. The graph illustrates the clock's behavior during transitions between two PTP inputs. It starts 'Locked to the PTP Input A', then 'PTP Input A is lost, clock goes into holdover and may generate a first transient'. In holdover, it is 'relying on local XO waiting for new selection of input'. When 'The clock selects the PTP Input B reference, transitions from holdover to lock, and may generate a second transient', it becomes 'Locked to the PTP Input B'. The graph shows two transient spikes in time error during these switching events. A small note in the bottom right corner reads 'G.8273.4-Y.1368.4(20)-Amd.2(22)_FVIII.1'.](8f7b458d3cc18ca96924473839d68ae6_img.jpg) + +Figure VIII.1 – Transients operation and switching budgeting. A graph showing Time error (ns) on the y-axis versus Time on the x-axis. The graph illustrates the clock's behavior during transitions between two PTP inputs. It starts 'Locked to the PTP Input A', then 'PTP Input A is lost, clock goes into holdover and may generate a first transient'. In holdover, it is 'relying on local XO waiting for new selection of input'. When 'The clock selects the PTP Input B reference, transitions from holdover to lock, and may generate a second transient', it becomes 'Locked to the PTP Input B'. The graph shows two transient spikes in time error during these switching events. A small note in the bottom right corner reads 'G.8273.4-Y.1368.4(20)-Amd.2(22)\_FVIII.1'. + +**Figure VIII.1 – Transients operation and switching budgeting** + +### VIII.4 Dynamic noise accumulation for PTS (constant temperature) + +In the dynamic noise analysis, the following assumptions were used: + +- Dynamic noise (dTE) may be analysed using a root-sum-square (RSS) approach. +- The dynamic noise is centred around the constant time error. +- The cTE portion of the noise at reference point C of [ITU-T G.8271.2] is a maximum of 1020 ns (of the 1100 ns limit). + +A maximum value of cTE was used to take into consideration that constant noise adds linearly whereas dynamic noise adds with RSS. If a larger portion of the noise is considered to be cTE, then there is less benefit to the RSS dynamic noise accumulation, which reduces the budget of the equipment dynamic noise wander generation, which in turn increases the complexity of the equipment design (for example a more stable oscillator may be needed). Note that the network limit at the reference point C of [ITU-T G.8271.2] is not currently specified or sub-divided between dTE and cTE in [ITU-T G.8271.2]. + +In Table VIII.2 the worst-case assumption of 1100 ns is taken for the limit at the reference point C of [ITU-T G.8271.2], with a worst-case maximum value of cTE of 1020 ns, leaving 160 ns for dTE (when the noise is centred). + +**Table VIII.2 – PTS dynamic noise key values (Constant temperature)** + +| Limit C dTE | Dynamic time error low-pass filtered noise generation (dTE L ) | +|-------------|---------------------------------------------------------------------------| +| 160 ns | 200 ns | + +Note the values in the Table VIII.2 are peak-peak values of dynamic noise. + +From Table VIII.2, the combined noise using RSS can be computed. + +- $\text{SQRT}(160^2 + 200^2)/2 + 1020 = 1148 \text{ ns}$ + +This 1148 ns dynamic noise for the worst-case assumption matches the maximum budget from Table VIII.1 related to input network limit at the reference point C of [ITU-T G.8271.2] and noise generation dTE. + +- $1100 \text{ ns} + 48 \text{ ns} = 1148 \text{ ns}$ + +## Bibliography + +- [b-ITU-T G.8262.1] Recommendation ITU-T G.8262.1/Y.1362.1 (2022), *Timing characteristics of an enhanced synchronous equipment slave clock.* +- [b-ITU-T G.8263] Recommendation ITU-T G.8263/Y.1363 (2017), *Timing characteristics of packet-based equipment clocks.* +- [b-ITU-T G.8273] Recommendation ITU-T G.8273/Y.1368 (2023), *Framework of phase and time clocks.* +- [b-Leland] Leland, W.E., Taqqu, M.S., Willinger, W., Wilson, D.V. (1994). *On the self-similar nature of Ethernet traffic* (extended version). *IEEE /ACM Trans. Networking*, 2, pp. 1–15. +- [b-Sahinoglu] Sahinoglu, Z., Tekinay, S. (1999). *On multimedia networks: self-similar traffic and network performance.* *IEEE Commun. Mag.*, 37, pp. 48–52. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects 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+(05/2020) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Packet over Transport aspects – Mobile network transport +aspects + +# --- **Characteristics of transport networks to support IMT-2020/5G** + +Recommendation ITU-T G.8300 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| Ethernet over Transport aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Synchronization, quality and availability targets | G.8200–G.8299 | +| Mobile network transport aspects | G.8300–G.8399 | +| Service Management | G.8600–G.8699 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.8300 + +# Characteristics of transport networks to support IMT-2020/5G + +## Summary + +Recommendation ITU-T G.8300 defines the requirements for the layer one transport network support for the 5G fronthaul, midhaul and backhaul networks as defined in this Recommendation. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.8300 | 2020-05-22 | 15 | 11.1002/1000/14217 | + +## Keywords + +Transport network, 5G. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2020 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 1 | +| 3.1 Terms defined elsewhere ..... | 1 | +| 3.2 Terms defined in this Recommendation..... | 1 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Reference transport network architecture for support of 5G mobile networks ..... | 3 | +| 7 Transport network OAM requirements ..... | 5 | +| 7.1 Path layer OAM requirements ..... | 5 | +| 7.2 Section layer OAM requirements ..... | 6 | +| 8 Considerations related to 5G network slicing..... | 6 | +| 9 Frequency and time synchronization in the transport network..... | 7 | +| 9.1 Synchronization requirement..... | 7 | +| 9.2 Synchronization solution for transport network ..... | 7 | +| 10 Survivability techniques in transport networks to support 5G ..... | 8 | +| Appendix I – End-to-end service latency in 5G networks ..... | 9 | +| Bibliography..... | 10 | + + + +## Recommendation ITU-T G.8300 + +# Characteristics of transport networks to support IMT-2020/5G + +# 1 Scope + +This Recommendation documents the requirements for the layer one transport network for 5G, including hard isolation between aggregated digital clients. The digital clients are the digital streams to/from the 5G entities (e.g., RU, DU, CU, 5GC/NGC) and other digital clients carried in the access, aggregation and core transport networks. The requirements and characteristics are documented for each of the fronthaul, midhaul and backhaul networks as defined in this Recommendation. + +The factors addressed include: + +- Relationship of 5G network architecture to transport network architecture +- Operations, administration, and maintenance (OAM) requirements +- Timing performance and time/synchronization distribution architecture +- Survivability mechanisms + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.805] Recommendation ITU-T G.805 (2000), *Generic functional architecture of transport networks*. +- [ITU-T G.8271] Recommendation ITU-T G.8271/Y.1366 (2020), *Time and phase synchronization aspects of telecommunication networks*. +- [ITU-T G.8271.1] Recommendation ITU-T G.8271.1/Y.1366.1 (2020), *Network limits for time synchronization in packet networks with full timing support from the network*. +- [ITU-T G.8273.2] Recommendation ITU-T G.8273.2/Y.1368.2 (2019), *Timing characteristics of telecom boundary clocks and telecom time slave clocks*. +- [ITU-T G.8275] Recommendation ITU-T G.8275/Y.1369 (2017), *Architecture and requirements for packet-based time and phase distribution*. +- [ITU-T G.8275.1] Recommendation ITU-T G.8275.1/Y.1369.1 (2020), *Precision time protocol telecom profile for phase/time synchronization with full timing support from the network*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +None. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|---------------------------------------------| +| 5GC | 5G Core | +| BS | Base Station | +| CPRI | Common Public Radio Interface | +| CN | Core Network | +| C-RAN | Cloud Radio Access Network | +| CU | Centralized Unit | +| D-RAN | Distributed Radio Access Network | +| DU | Distributed Unit | +| eCPRI | enhanced Common Public Radio Interface | +| eMBB | enhanced Mobile Broadband | +| eOEC | enhanced OTN Equipment Clock | +| ePRC | enhanced Primary Reference Clock | +| ePRTC | enhanced Primary Reference Time Clock | +| eSEC | enhanced Synchronous Equipment Clock | +| gNB | Next generation NodeB | +| HLS | High-Layer Split | +| HRM | Hypothetical Reference Model | +| MAC | Media Access Control layer | +| MBB | Mobile Broadband | +| mCDN | mobile Content Delivery Network | +| MEC | Multi-access Edge Computing | +| mMTC | massive Machine-Type Communication | +| OAM | Operations, Administration, and Maintenance | +| OEC | OTN Equipment Clock | +| OSS | Operations Support System | +| OTN | Optical Transport Network | +| PDCP | Packet Data Convergence Protocol | +| PHY | Physical layer | +| PRC | Primary Reference Clock | +| PRTC | Primary Reference Time Clock | +| PTP | Precision Time Protocol | +| RAN | Radio Access Network | +| RBU | Radio Baseband Unit | +| RRU | Remote Radio Unit | +| RU | Radio Unit | + +| | | +|-------|------------------------------------------| +| SEC | Synchronous Equipment Clock | +| SLA | Service Level Agreement | +| T-BC | Telecom Boundary Clock | +| T-TC | Telecom Transparent Clock | +| TCM | Tandem Connection Monitoring | +| UE | User Equipment | +| URLLC | Ultra-Reliable Low Latency Communication | +| VN | Virtual Network | + +# 5 Conventions + +This Recommendation uses the following conventions: + +| | | +|----|------------------------------------------------------------------------------------------------------------| +| F1 | Logical interface between the CU and DU | +| NG | Logical interface between the 5GC and gNB | +| Xn | (Logical) Interfaces internal to the RAN ("Xn" specifically refers to one connected between two gNB nodes) | + +# 6 Reference transport network architecture for support of 5G mobile networks + +The architecture of the transport network is often described in terms of metro access, metro aggregation, metro core, and backbone domains. When considering transport for 5G, an alternative description based on 5G applications is useful in understanding the requirements. + +The 5G RAN architecture is described in [b-3GPP TS 38.401]. + +For purposes of describing the transport network for 5G, the 5G network comprises remote radio unit (RRU), distributed unit (DU), centralized unit (CU), and core network. The terms fronthaul, midhaul, and backhaul are used in this Recommendation when describing the 5G transport network support for the interfaces between these nodes. + +A fronthaul transport network supports the low-layer functional split point of 3GPP NG-RAN (e.g., Option 6 for MAC/PHY split or Option 7 for intra PHY split) [b-3GPP TR 38.801]. + +A midhaul transport network supports 3GPP NG-RAN F1 interface (between a gNB-CU and a gNB-DU), or the Xn interface that provides interconnection between different NG-RAN nodes (gNB). + +A backhaul transport network supports the 3GPP NG interface (between the 5GC and the NG-RAN) or the Xn interface that provides interconnection between different NG-RAN nodes (gNB) [b-3GPP TS 38.401]. + +The deployment of IMT2020/5G RAN can be characterized based on the location of the DU and CU, as illustrated in Figure 6-1. Several observations can be made about the transport network based on this figure: + +- A backhaul network always exists to connect the CUs to the core network. +- When DU and RU are integrated, there is no fronthaul network. +- When the DU and CU are integrated, there is no midhaul network. + +Although not shown in Figure 6-1, the Xn interface between CU nodes would transit either a midhaul or backhaul network. + +![Figure 6-1: Example overview of a 5G transport network. The diagram shows four network architectures connected to a central 'Core network'. Top-left: 'Distributed RAN' with two gNBs (each containing CU and DU) connected via 'Backhaul S1/NG' to the core. Top-right: 'Distributed RAN + Virtualized RAN (HLS)' where a 'Data centre' containing a CU is connected via 'Midhaul F1' to an 'HLS-gNB' (DU) and an 'HLS-RBU' (Small/street site). Bottom-left: 'Centralized RAN' where a 'Central office site' containing CU and DU is connected via 'Fronthaul CPRI/eCPRI' to multiple RRU units and via 'Midhaul F1' to an 'HLS-RBU'. Bottom-right: 'Centralized RAN + Virtualized RAN (HLS)' where a 'Central office site' containing a DU is connected via 'Fronthaul CPRI/eCPRI' to multiple RRU units and via 'Midhaul F1' to an 'HLS-gNB'.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Figure 6-1: Example overview of a 5G transport network. The diagram shows four network architectures connected to a central 'Core network'. Top-left: 'Distributed RAN' with two gNBs (each containing CU and DU) connected via 'Backhaul S1/NG' to the core. Top-right: 'Distributed RAN + Virtualized RAN (HLS)' where a 'Data centre' containing a CU is connected via 'Midhaul F1' to an 'HLS-gNB' (DU) and an 'HLS-RBU' (Small/street site). Bottom-left: 'Centralized RAN' where a 'Central office site' containing CU and DU is connected via 'Fronthaul CPRI/eCPRI' to multiple RRU units and via 'Midhaul F1' to an 'HLS-RBU'. Bottom-right: 'Centralized RAN + Virtualized RAN (HLS)' where a 'Central office site' containing a DU is connected via 'Fronthaul CPRI/eCPRI' to multiple RRU units and via 'Midhaul F1' to an 'HLS-gNB'. + +Figure 6-1 – Example overview of a 5G transport network + +Table 6-1 provides a mapping of terminology used to describe the 5G transport network to the domains of the transport network. + +Table 6-1 – Terminology mapping + +| 3GPP logical interface or CPRI Name | Network name in this Recommendation | Interface description | Transport network domains | +|-------------------------------------|-------------------------------------|------------------------------------------------------------------------------------------------------------|----------------------------------------------------------| +| CPRI/eCPRI | Fronthaul | Interface between RRU and DU | Metro access | +| F1 | Midhaul | Logical interface between the CU and DU | Metro- access or metro aggregation | +| NG | Backhaul | Logical interface between the gNB (CU) and the 5GC | Metro access, metro aggregation, metro core, or backbone | +| Xn | Midhaul or Backhaul | Logical interface between gNB nodes (between the packet data convergence protocol (PDCP) function of each) | Metro access, metro aggregation, metro core, or backbone | + +Several examples of the mapping described in Table 6-1 are illustrated in Figure 6-2. + +![Figure 6-2: Examples of mapping transport network domains to 5G network names. The diagram shows four horizontal layers representing different network configurations. Each layer shows a sequence of components: DU (yellow box), CU (yellow box), and NG (yellow box) connected by lines. The first layer shows DU and CU connected to a single NG. The second layer shows DU connected to NG, with a CU connected to the NG via an Xn interface. The third layer shows DU connected to CU, which is connected to NG. The fourth layer shows DU connected to NG, with a CU connected to the NG via an Xn interface. Below these layers, three transport network domains are indicated by double-headed arrows: 'Metro access' (under the first layer), 'Metro aggregation' (under the second and third layers), and 'Metro core and backbone' (under the fourth layer). A vertical yellow bar on the right is labeled 'Core node'. The diagram is labeled 'G.8300(20)_F6-2' at the bottom right.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Figure 6-2: Examples of mapping transport network domains to 5G network names. The diagram shows four horizontal layers representing different network configurations. Each layer shows a sequence of components: DU (yellow box), CU (yellow box), and NG (yellow box) connected by lines. The first layer shows DU and CU connected to a single NG. The second layer shows DU connected to NG, with a CU connected to the NG via an Xn interface. The third layer shows DU connected to CU, which is connected to NG. The fourth layer shows DU connected to NG, with a CU connected to the NG via an Xn interface. Below these layers, three transport network domains are indicated by double-headed arrows: 'Metro access' (under the first layer), 'Metro aggregation' (under the second and third layers), and 'Metro core and backbone' (under the fourth layer). A vertical yellow bar on the right is labeled 'Core node'. The diagram is labeled 'G.8300(20)\_F6-2' at the bottom right. + +**Figure 6-2 – Examples of mapping transport network domains to 5G network names** + +Beyond the transport plane shown in Figure 6-2, the transport network architecture also includes management and synchronization planes. Together these components enable support for the applications of 5G, multi-access Edge computing (MEC), and mobile content delivery network (mCDN) network interconnection as well as private line services. To facilitate service level agreement (SLA) guarantees, virtual network resource capabilities are supported to enable differentiated network slicing, which requires coordinated management and control of the 5G core network, transport network, and radio access network (RAN). Figure 6-3 illustrates this broader view of the transport network. + +![Figure 6-3: Overview of 5G transport network. The diagram is divided into three horizontal planes. The top plane is the 'Management and control plane', containing an 'Orchestrator/OSS' at the top, followed by 'RAN management and control', 'Transport network management/control', 'Management', 'Control', 'Monitoring and analysis', and '5G core controller'. The middle plane is the 'Transport plane', showing a network of nodes and links. It includes 'RRU', 'gNB', 'DU', 'CU', 'MEC uRLLC', 'eMBB', 'mMTC', 'Backbone node', and 'PRTC/ePRTC'. The bottom plane is the 'Synchronization' plane, showing 'Synchronization' links between nodes. Below the transport plane, 'Virtual network services' are shown, including '5G network slicing' with 'MBB/eMBB slicing', 'mMTC slicing', 'URLLC slicing', 'MEC and mCDN slicing', and 'Business private network slicing'. These are grouped under 'Differentiated network slicing service capabilities'. The diagram is labeled 'G.8300(20)_F6-3' at the bottom right.](5a4e62bead259c258d069fd3663ea670_img.jpg) + +Figure 6-3: Overview of 5G transport network. The diagram is divided into three horizontal planes. The top plane is the 'Management and control plane', containing an 'Orchestrator/OSS' at the top, followed by 'RAN management and control', 'Transport network management/control', 'Management', 'Control', 'Monitoring and analysis', and '5G core controller'. The middle plane is the 'Transport plane', showing a network of nodes and links. It includes 'RRU', 'gNB', 'DU', 'CU', 'MEC uRLLC', 'eMBB', 'mMTC', 'Backbone node', and 'PRTC/ePRTC'. The bottom plane is the 'Synchronization' plane, showing 'Synchronization' links between nodes. Below the transport plane, 'Virtual network services' are shown, including '5G network slicing' with 'MBB/eMBB slicing', 'mMTC slicing', 'URLLC slicing', 'MEC and mCDN slicing', and 'Business private network slicing'. These are grouped under 'Differentiated network slicing service capabilities'. The diagram is labeled 'G.8300(20)\_F6-3' at the bottom right. + +**Figure 6-3 – Overview of 5G transport network** + +# 7 Transport network OAM requirements + +The 5G transport network consists of both path and section layers, each having its own OAM. + +## 7.1 Path layer OAM requirements + +The transport network path layer OAM functions shall meet the following basic requirements: + +- 1) Each path layer shall support its own suitable OAM function set. +- 2) Each path OAM function shall support on demand enabling or disabling commands. A disabled OAM function shall release resources that it occupied during the enabled period. +- 3) OAM information is inserted or extracted at the path channel end point. Both inserting and extracting operations shall have a minimum impact on latency and system complexity. Support for non-intrusive monitoring of path OAM is optional. + +Support for tandem connection monitoring (TCM) and a path layer management communications channel is for further study + +The path OAM functions shall support the following: + +- a) Continuity supervision +- b) Connectivity supervision +- c) Error performance monitoring +- d) Remote defect and error reporting +- e) Delay measurement (in-service and out-of-service) +- f) Protection communications channel +- g) Client signal fail indication + +Each type of OAM function is activated by enable and disable commands. Some OAM information may be sent and received periodically. The periodicity could be made configurable and on -demand. In any case, the periodicity must be suitable to the type of OAM. All types of OAM functions are independent to each other. + +### **7.1.1 Delay measurement** + +Both in-service and out-of-service delay measurements may be required, depending on the service. Some services may need only an out of service measurement prior to activating the service, while others may require more frequent monitoring of delay to ensure performance requirements are being satisfied. + +Both one-way and two-way delay measurements are needed. + +Appendix I includes additional information regarding end-to-end latency in 5G networks. + +## **7.2 Section layer OAM requirements** + +The section layer OAM functions can provide the performance supervision and management, and should include the following functions: + +- a) Connectivity supervision, monitoring the integrity of the routing of connectivity of a connection between source and sink terminations. +- b) Maintenance information, including forward and backward defect indications and backward error reporting. +- c) Connection quality supervision, monitoring the performance of a connection. +- d) Management communications channel. +- e) Server signal fail indication. + +# **8 Considerations related to 5G network slicing** + +The transport network is, in general, a multi-service network and, in most cases, a common transport network infrastructure will be shared between 5G services and other types of services. It is necessary to provide isolation between each of these services. From a management perspective, the + +services are supported by virtual networks (VNs). The forwarding plane must ensure that the traffic from one VN is not (accidentally) delivered to a different VN. It is also necessary for the forwarding plane to provide isolation that limits the interaction between the traffic in different VNs. + +# 9 Frequency and time synchronization in the transport network + +In the 5G transport network, frequency and phase/time synchronization are needed to support requirements at the air interface of a mobile system. This clause describes 5G synchronization requirements and defines the synchronization solution for the transport network. + +## 9.1 Synchronization requirement + +Requirements for the frequency offset at the air interface of 5G RRUs are described in [b-3GPP TS 38.104]. + +The relevant phase/time synchronization requirements are listed in Tables II.1 and II.2 of [ITU-T G.8271]. + +## 9.2 Synchronization solution for transport network + +For meeting frequency and phase/time synchronization requirements, the full timing support solution, which is defined in [ITU-T G.8275], should be used in the transport network. This solution requires that every node between the clock server and the end application node should support the synchronous equipment clock or enhanced synchronous equipment clock SEC/eSEC and the telecom boundary clock (T-BC) or telecom transparent clock (T-TC) [ITU-T G.8271.1] clock. Figure 9-1 is a generic synchronization topology for the transport network and represents one example of how such a network could be constructed. + +![Figure 9-1: Example of synchronization transport network topology. The diagram illustrates a network architecture divided into three main segments: Access (10 ~ 20 km), Metro-Aggregation (40 ~ 80 km), and Metro-Core. On the left, multiple RRU (Radio Remote Unit) units are connected to a central DU (Distributed Unit) or DU+CU (Central Unit) within a C-RAN or D-RAN. These are connected via 100G/200G or N*25G links. The central part shows a mesh of nodes connected by N*25G/50G and N*100G/200G links, with MEC (Multi-access Edge Computing) units and CU (Central Unit) nodes. The right side shows the Metro-Core with PRC/ePRC (Primary Reference Clock) and PRTC/ePRTC (Primary Reference Time Clock) units connected to 'New core' nodes. Various synchronization paths are indicated by colored lines (red, blue, green, yellow) connecting the clocks to the various network elements.](4636adff5682a064f0ae5f13a1d464a6_img.jpg) + +Figure 9-1: Example of synchronization transport network topology. The diagram illustrates a network architecture divided into three main segments: Access (10 ~ 20 km), Metro-Aggregation (40 ~ 80 km), and Metro-Core. On the left, multiple RRU (Radio Remote Unit) units are connected to a central DU (Distributed Unit) or DU+CU (Central Unit) within a C-RAN or D-RAN. These are connected via 100G/200G or N\*25G links. The central part shows a mesh of nodes connected by N\*25G/50G and N\*100G/200G links, with MEC (Multi-access Edge Computing) units and CU (Central Unit) nodes. The right side shows the Metro-Core with PRC/ePRC (Primary Reference Clock) and PRTC/ePRTC (Primary Reference Time Clock) units connected to 'New core' nodes. Various synchronization paths are indicated by colored lines (red, blue, green, yellow) connecting the clocks to the various network elements. + +Figure 9-1 – Example of synchronization transport network topology + +Generally, the frequency reference master primary reference clock PRC/ePRC is deployed in the core network, and the phase/time master primary reference time clock or enhanced primary reference time clock PRTC/ePRTC is deployed in the access, aggregation, or core network. The + +deployment position is limited by the number of hops from the clock server to the RRU, which is described in the hypothetical reference models (HRMs) of [ITU-T G.8271.1]. + +For the frequency synchronization solution, the transport nodes between the PRC/ePRC and RRU shall support the appropriate SEC or eSEC physical layer clock. + +For the phase/time synchronization solution, the transport nodes between the PRTC/ePRTC and RRU shall support the T-BC precision time protocol (PTP) layer clock. The clock specification is [ITU-T G.8273.2] and the network limit is defined in [ITU-T G.8271.1], and the PTP full timing support profile is [ITU-T G.8275.1]. + +NOTE – Optical layer nodes without optical protection/restoration are not required to support the OTN equipment clock (OEC), enhanced OTN equipment clock (eOEC) or T-BC. This is because these nodes do not affect the accuracy of the transport synchronization network. + +# **10 Survivability techniques in transport networks to support 5G** + +General characteristics of transport protection mechanisms are described in the ITU-T G.808.x series of Recommendations. + +Protection or restoration mechanisms should be used in the 5G transport network as necessary to meet the requirements of the services being carried over the 5G network. In order to allow for deployment of survivability mechanisms in multiple layers, any new protection or restoration mechanisms should support the use of hold-off timers. + +# Appendix I + +### End-to-end service latency in 5G networks + +(This appendix does not form an integral part of this Recommendation.) + +End-to-end service latency is an important characteristic of 5G networks. Table I.1 summarizes requirements for end-to-end latency for some types of services based on [b-3GPP TR 38.913]. + +**Table I.1 – End to end latency requirements for selected service types** + +| Service type | | Latency requirement | +|--------------|-------------------------|---------------------| +| eMBB | User plane (UE- CU/MEC) | 4 ms | +| | Control plane (UE-CN) | 10 ms | +| URLLC | User plane (UE-CU/MEC) | 0.5 ms~1 ms | +| | Control plane (UE-CN) | 10 ms | + +Figure I.1 illustrates an example of how the end-to-end latency budget could be allocated to different nodes and transport networks within the 5G architecture. + +![Diagram illustrating the allocation of end-to-end latency budget across 5G network components. The components are 5G user equipment, 5G RRU, 5G DU, Access, 5G CU/MEC, Aggregation and core, and 5G CN. Latency components are labeled T0 through T8. Total latency requirements are shown for URLLC (0.5 - 1 ms), eMBB user plane (4 ms), and Control plane (10 ms).](bffdddb47fced140f8d17fdc2a29f592_img.jpg) + +The diagram shows the flow of data and latency components through the 5G architecture. The components are: 5G user equipment, 5G RRU, 5G DU, Access, 5G CU/MEC, Aggregation and core, and 5G CN. The latency components are labeled as follows: + +- T0: Process delay at 5G user equipment +- T1: Wireless transmission delay between 5G user equipment and 5G RRU +- T2: Process delay at 5G RRU +- T3: Fronthaul transmission delay between 5G RRU and 5G DU +- T4: Process delay at 5G DU +- T5: Midhaul transmission delay between 5G DU and 5G CU/MEC +- T6: Process delay at 5G CU/MEC +- T7: Backhaul transmission delay between 5G CU/MEC and 5G CN +- T8: Process delay at 5G CN + +Latency budget allocations are shown as horizontal bars: + +- 0.5 - 1 ms (URLLC): From T0 to T6 +- 4 ms (eMBB user plane): From T0 to T6 +- 10 ms (Control plane): From T0 to T8 + +G.8300(20)\_FI.1 + +Diagram illustrating the allocation of end-to-end latency budget across 5G network components. The components are 5G user equipment, 5G RRU, 5G DU, Access, 5G CU/MEC, Aggregation and core, and 5G CN. Latency components are labeled T0 through T8. Total latency requirements are shown for URLLC (0.5 - 1 ms), eMBB user plane (4 ms), and Control plane (10 ms). + +**Figure I.1 – Example allocation of end-to-end latency** + +# Bibliography + +- [b-3GPP TR 38.801] 3GPP TR 38.801 (2017), *Technical Specification Group Radio Access Network; Study on new radio access technology: Radio access architecture and interfaces*, March. +- [b-3GPP TR 38.913] 3GPP TR 38.913, *Study on Scenarios and Requirements for Next Generation Access Technologies*. +- [b-3GPP TS 38.104] 3GPP TS 38.104, V16.2.0 (2019-12), *NR, Base Station (BS) radio transmission and reception*. +- [b-3GPP TS 38.401] 3GPP TS 38.401, V15.1.0 (2018-03), *NG-RAN; Architecture description (Release 15)*. +- [b-eCPRI] eCPRI Specification V1.0 (2017), *Common Public Radio Interface: eCPRI Interface Specification*, August. + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git 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SECTOR +OF ITU + +**G.832** + +(10/98) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – Network +capabilities and functions + +--- + +**Transport of SDH elements on PDH networks – +Frame and multiplexing structures** + +ITU-T Recommendation G.832 + +(Previously CCITT Recommendations) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Telecommunications management network | G.850–G.859 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +*For further details, please refer to ITU-T List of Recommendations.* + +# **TRANSPORT OF SDH ELEMENTS ON PDH NETWORKS – FRAME AND MULTIPLEXING STRUCTURES** + +## **Summary** + +This Recommendation defines frame structures and multiplexing arrangements for the transport of SDH elements over existing PDH transport networks operating at G.702 hierarchical rates of 34 368 kbit/s, 44 736 kbit/s, 97 728 kbit/s and 139 264 kbit/s. It is envisaged that these frame structures could, unless otherwise indicated, be used for the transport of other signals (e.g. ATM cells). + +## **History** + +| Issue | Notes | +|-------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 02/98 | Second revision: Modifications are made to subclauses 2.1.2, 2.4.2, 3.1.1 and 3.4.3 to support the Synchronization Status Message (SSM) instead of the timing marker in bit 8 of byte MA in the 34 368 and 139 264 kbit/s signals.
The NR byte definition is modified and now aligned with the definition of byte N1 in Annex D/G.707. | +| 11/95 | First revision: Terms FERF and FEBE are replaced by RDI and REI. References to Recommendations G.708 and G.709 are replaced by references to Recommendation G.707. The trail trace identifier specification has been modified and refers to Recommendations G.707 and G.831. | +| 11/93 | Initial version | + +## **Source** + +ITU-T Recommendation G.832 was revised by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 13th of October 1998. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | Page | | +|---------|----------------------------------------------------------------------------|----| +| 1 | Introduction ..... | 1 | +| 1.1 | Scope ..... | 1 | +| 1.2 | References ..... | 1 | +| 1.3 | Abbreviations ..... | 1 | +| 2 | Frame structures ..... | 2 | +| 2.1 | Frame structure at 34 368 kbit/s ..... | 2 | +| 2.1.1 | General ..... | 2 | +| 2.1.2 | Overhead allocation ..... | 3 | +| 2.2 | Frame structure at 44 736 kbit/s ..... | 4 | +| 2.2.1 | Intermediate 500 µs frame structure ..... | 4 | +| 2.2.2 | Overhead allocation ..... | 5 | +| 2.3 | Frame structure at 97 728 kbit/s ..... | 5 | +| 2.3.1 | General ..... | 5 | +| 2.3.2 | Overhead allocation ..... | 6 | +| 2.4 | Frame structure at 139 264 kbit/s ..... | 7 | +| 2.4.1 | General ..... | 7 | +| 2.4.2 | Overhead allocation ..... | 7 | +| 3 | Multiplexing structures ..... | 9 | +| 3.1 | Support of SDH elements in the 34 368 kbit/s frame structure..... | 9 | +| 3.1.1 | Coding of multiframe indicator for Tributary Unit multiframe indication... | 10 | +| 3.2 | Support of SDH elements in the 44 736 kbit/s frame structure..... | 11 | +| 3.3 | Support of SDH elements in the 97 728 kbit/s frame structure..... | 12 | +| 3.4 | Support of SDH elements in the 139 264 kbit/s frame structure..... | 13 | +| 3.4.1 | Multiplexing of 20 × TUG-2..... | 13 | +| 3.4.2 | Multiplexing of 2 × TUG-3 and 5 × TUG-2 ..... | 14 | +| 3.4.3 | Coding of multiframe indicator for Tributary Unit multiframe indication... | 15 | +| Annex A | – Description of the 16-byte frame and CRC-7 calculation..... | 16 | + + + +## Recommendation G.832 + +# TRANSPORT OF SDH ELEMENTS ON PDH NETWORKS – FRAME AND MULTIPLEXING STRUCTURES + +(revised in 1998) + +# 1 Introduction + +## 1.1 Scope + +The purpose of this Recommendation is to provide frame structures and multiplexing arrangements for the transport of SDH elements over existing PDH transport networks operating at various G.702 hierarchical rates. It is also envisaged that these frame structures could, unless otherwise indicated, be used for the transport of other signals (e.g. ATM cells). + +## 1.2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- ITU-T Recommendation G.707 (1996), *Network node interface for the Synchronous Digital Hierarchy (SDH)*. +- ITU-T Recommendation G.804 (1998), *ATM cell mapping into Plesiochronous Digital Hierarchy (PDH)*. +- CCITT Recommendation T.50 (1992), *International Reference Alphabet (IRA) (Formerly International Alphabet No. 5 or IA5) – Information technology – 7-bit coded character set for information interchange*. + +## 1.3 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|-------|----------------------------------| +| BIP-8 | Bit Interleaved Parity-8 | +| C-n | Container of level n | +| IEC | Incoming Error Count | +| LSB | Least Significant Bit | +| MFI | MultiFrame Indicator | +| MSB | Most Significant Bit | +| PDH | Plesiochronous Digital Hierarchy | +| POH | Path Overhead | +| PTR | PoinTeR | +| RDI | Remote Defect Indication | +| REI | Remote Error Indication | + +| | | +|-------|---------------------------------| +| SDH | Synchronous Digital Hierarchy | +| SOH | Section Overhead | +| TTI | Trail Trace Identifier | +| TU-n | Tributary Unit of level n | +| TUG-n | Tributary Unit Group of level n | +| VC-n | Virtual Container of level n | + +NOTE 1 – The order of transmission of information in all diagrams in this Recommendation is first from left to right and then top to bottom. Within each byte the most significant bit is transmitted first. The most significant bit (bit 1) is illustrated at the left of all diagrams. + +NOTE 2 – In this Recommendation the term "SDH elements" indicates the various VCs with their associated pointers. + +# 2 Frame structures + +The frame structures defined in this Recommendation are intended to be used in a generic way. When implementing these frame structures, care should be taken to ensure that the performance of the frame alignment mechanism is not compromised by the payload content. + +## 2.1 Frame structure at 34 368 kbit/s + +### 2.1.1 General + +The basic frame structure at 34 368 kbit/s comprises 7 octets of overhead and 530 octets of payload capacity per 125 µs as shown in Figure 2-1. + +![Diagram of the frame structure at 34 368 kbit/s. It shows a rectangular frame with 59 columns and 9 rows. The first column contains 7 overhead octets: FA1, FA2, EM, TR, MA, NR, and GC. The remaining 58 columns and 9 rows (totaling 530 octets) are designated as payload. A label 'T1302700-94' is in the bottom right corner.](e1a0d046fbe7f28f5e93a47091851747_img.jpg) + +The diagram illustrates the frame structure at 34 368 kbit/s. It consists of a grid of 59 columns and 9 rows. The first column is divided into seven cells representing overhead octets: FA1, FA2, EM, TR, MA, NR, and GC. The remaining area, spanning columns 2 through 59 and all 9 rows, is labeled as '530 octet payload'. Above the grid, a horizontal double-headed arrow indicates '59 columns'. To the right of the grid, a vertical double-headed arrow indicates '9 rows'. In the bottom right corner, outside the main grid, is the text 'T1302700-94'. + +Diagram of the frame structure at 34 368 kbit/s. It shows a rectangular frame with 59 columns and 9 rows. The first column contains 7 overhead octets: FA1, FA2, EM, TR, MA, NR, and GC. The remaining 58 columns and 9 rows (totaling 530 octets) are designated as payload. A label 'T1302700-94' is in the bottom right corner. + +Figure 2-1/G.832 – Frame structure at 34 368 kbit/s + +### 2.1.2 Overhead allocation + +The values and allocation of the overhead bytes are shown in Figure 2-2 and are described below. + +![](562f471e8153729557e6a4ee6343c32c_img.jpg) + +| | | | | | | | | | | | | | | | | | | +|-----|-------------|-----|--------------|---|-----|---|-----|---|---|---|---|---|---|---|---|---|-----| +| FA1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | FA2 | +| EM | BIP-8 | | | | | | | | | | | | | | | | | +| TR | Trail Trace | | | | | | | | | | | | | | | | | +| MA | RDI | REI | Payload type | | MFI | | SSM | | | | | | | | | | | +| NR | NR | | | | | | | | | | | | | | | | | +| GC | GC | | | | | | | | | | | | | | | | | + +T1302710-94 + +**Figure 2-2/G.832 – Overhead allocation at 34 368 kbit/s** + +#### FA1/FA2 + +Frame Alignment signal. This has the same pattern as A1/A2 defined in Recommendation G.707. + +#### EM + +Error Monitoring, BIP-8. One byte is allocated for error monitoring. This function shall be a BIP-8 code using even parity. The BIP-8 is calculated over all bits, including the overhead bits, of the previous 125 µs frame. The computed BIP-8 is placed in the EM byte of the current 125 µs frame. + +#### TR + +Trail Trace. This byte is used to repetitively transmit a trail access point identifier so that a trail receiving terminal can verify its continued connection to the intended transmitter. The trail access point identifier shall use the access point identifier format as defined in clause 3/G.831. + +A 16-byte frame is defined for the transmission of the access point identifier and this is described in Annex A. + +#### MA Maintenance and Adaptation byte + +Bit 1 RDI + +Bit 2 REI – This bit is set to "1" and sent back to the remote trail termination if one or more errors were detected by the BIP-8, and is otherwise set to zero. + +Bits 3 to 5 Payload type + +| Code | Signal | +|------|------------------------| +| 000 | Unequipped | +| 001 | Equipped, non-specific | +| 010 | ATM | +| 011 | SDH TU-12s | + +Bits 6-7 Multiframe indicator + +Bit 8 This bit is used in a four-frame multiframe. The phase of the multiframe is determined by the value of MA bits 6 and 7, according to: + +| Bit 6 | Bit 7 | Bit 8 | +|--------------|--------------|-----------------| +| 0 | 0 | SSM bit 1 (MSB) | +| 0 | 1 | SSM bit 2 | +| 1 | 0 | SSM bit 3 | +| 1 | 1 | SSM bit 4 (LSB) | + +The four bits of the multiframe are allocated to the Synchronization Status Message (SSM). The coding of the SSM is given in Table 5/G.707. + +When interworking with "old" equipment which used bit 8 as a timing marker (non-multiframe), the "new" equipment implementing the above requirement should be capable of being configured to transmit the "old" requirement as given below: + +Bit 8, Timing marker. This bit is set to "0" to indicate that the timing source is traceable to a Primary Reference Clock, and is otherwise set to "1". + +#### **NR** + +Network Operator byte. This byte is allocated for maintenance purposes specific to individual Network Operators. Its transparency from Trail termination to Trail termination is not guaranteed. In the case where this byte is modified at an intermediate point in the trail, the EM byte must be appropriately corrected to ensure performance monitoring integrity. For Tandem Connection Maintenance, the byte is used in accordance with Annex D/G.707. + +#### **GC** + +General purpose communications channel (e.g. to provide data/voice channel connection for maintenance purposes). + +## **2.2 Frame structure at 44 736 kbit/s** + +The basic frame structure at 44 736 kbit/s is described in Recommendation G.704. + +### **2.2.1 Intermediate 500 µs frame structure** + +Since the 44 736 kbit/s frame structure is an asynchronous format with a nominal frame time of 106.402 µs, an intermediate 500 µs frame structure is defined below. This frame consists of 2736 bytes of payload, 4 framing bytes and 19 bytes of fixed stuff as shown in Figure 2-3. + +![Diagram of the intermediate 500 µs frame structure. It shows a rectangular frame with 19 columns and 144 rows. The top-left corner contains four bytes labeled F1, F2, F3, and F4. The first 23 rows of the frame are designated as 'Fixed stuff'. The remaining area, from row 24 to row 144 across all 19 columns, is labeled '2736 bytes of payload capacity'. A legend at the bottom left shows a small rectangle labeled 'Fixed stuff'. The diagram is identified by the code T1304180-95.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Diagram of the intermediate 500 µs frame structure. It shows a rectangular frame with 19 columns and 144 rows. The top-left corner contains four bytes labeled F1, F2, F3, and F4. The first 23 rows of the frame are designated as 'Fixed stuff'. The remaining area, from row 24 to row 144 across all 19 columns, is labeled '2736 bytes of payload capacity'. A legend at the bottom left shows a small rectangle labeled 'Fixed stuff'. The diagram is identified by the code T1304180-95. + +**Figure 2-3/G.832 – Intermediate 500 µs frame structure +for transport of SDH elements in the +44 736 kbit/s frame structure** + +When this intermediate frame is combined along with the 44 736 kbit/s frame level stuffing and the 56 frame overhead bits of the C-bit parity format, the resultant signal will be 44 736 095 bit/s (within the range of the nominal 44 736 kbit/s $\pm$ 20 ppm). + +### 2.2.2 Overhead allocation + +The framing bytes and fixed stuff bytes are defined below. + +- F1 – 11110110 +- F2 – 00101000 +- F3 – 11110110 +- F4 – 00101000 +- Fixed stuff – 11001100 + +## 2.3 Frame structure at 97 728 kbit/s + +### 2.3.1 General + +Using the full 97 728 kbit/s rate, there are 1537 bytes available every 125 µs. As the net capacity of the Container-3 needs 756 bytes every 125 µs, two Container-3s can be allocated leaving 15 bytes every 125 µs for the overhead for the 97 728 kbit/s signal and VC-3 POH functionality and for pointers as shown in Figure 2-4. + +![Diagram of frame structure and overhead allocation for 97 728 kbit/s. It shows a 168-byte frame with a 10-byte overhead (A1, A2, D, Ha, Hb) and a 1522-byte payload. The payload contains a 756-byte payload and a 9-byte POH (J1, B3, C2/G1, F2, H4). The POH is further detailed with a 1-byte J1 and an 84-byte section containing B3, C2/G1, F2, and H4. A table on the left defines the overhead bytes: A1 (11110110), A2 (001010MM), D (Data Communication Channel), Ha, Hb, MM, H1, H2, H3, B2, K1. The POH section is also detailed with a 1-byte J1 and an 84-byte section containing B3, C2/G1, F2, and H4.](d4af765160d04ecef538e5066006dc77_img.jpg) + +A1: 11110110 +A2: 001010MM +(MM = 00/01/10/11) +D: Data Communication Channel + +| MM | Ha | Hb | +|----|----|----| +| 00 | H1 | H1 | +| 01 | H2 | H2 | +| 10 | H3 | H3 | +| 11 | B2 | K1 | + +H1, H2, H3 Pointer +B2 BIP-8 +K1 RDI + +T1302720-94 + +Diagram of frame structure and overhead allocation for 97 728 kbit/s. It shows a 168-byte frame with a 10-byte overhead (A1, A2, D, Ha, Hb) and a 1522-byte payload. The payload contains a 756-byte payload and a 9-byte POH (J1, B3, C2/G1, F2, H4). The POH is further detailed with a 1-byte J1 and an 84-byte section containing B3, C2/G1, F2, and H4. A table on the left defines the overhead bytes: A1 (11110110), A2 (001010MM), D (Data Communication Channel), Ha, Hb, MM, H1, H2, H3, B2, K1. The POH section is also detailed with a 1-byte J1 and an 84-byte section containing B3, C2/G1, F2, and H4. + +**Figure 2-4/G.832 – Frame structure and overhead allocation for the 97 728 kbit/s** + +### 2.3.2 Overhead allocation + +The overheads and pointers are described below. + +A1, A2 Frame alignment signal: + +A1 11110110 + +A2 001010MM, + +where MM (= 00/01/10/11) is multiframe indicator for Ha and Hb bytes. + +D A 64 kbit/s data communication channel. + +Ha, Hb These multiframe structured bytes have the following functionality: + +H1, H2, H3 Reduced AU-3 pointer, which has the same function as defined in Recommendation G.707. + +B2 Error monitoring, BIP-8. One byte is allocated for error monitoring of the 97 728 kbit/s signal. This function shall be a BIP-8 code using even parity. The BIP-8 is calculated over all bits of the previous 500 μs multiframe. The computed BIP-8 is placed in the B2 byte of the current 500 μs multiframe. + +K1 Bit 8 is used for RDI. Bits 1-7 are reserved for future use. + +J1 VC-3 path trace as defined in Recommendation G.707. + +B3 VC-3 path BIP-8 as defined in Recommendation G.707. + +C2/G1 Bits 1-4 are for VC-3 path REI, bit 5 is for VC-3 RDI and bits 6-8 are for VC-3 signal label. + +F2 VC-3 path user channel as defined in Recommendation G.707. + +H4 VC-3 position indicator as defined in Recommendation G.707. + +## 2.4 Frame structure at 139 264 kbit/s + +### 2.4.1 General + +The basic frame structure at 139 264 kbit/s comprises 16 octets of overhead and 2160 octets of payload capacity per 125 µs as shown in Figure 2-5. + +![Diagram of frame structure at 139 264 kbit/s showing 240 columns and 9 rows. The first two columns are overhead (FA1, FA2, EM, P1, TR, P2, MA, NR, GC) and the remaining 238 columns are the 2160 octet payload. A legend indicates that grey cells are 'Not yet defined'.](ff0952ef692c9d960ce5f6708bcc9711_img.jpg) + +Diagram illustrating the frame structure at 139 264 kbit/s. The frame consists of 240 columns and 9 rows. The first two columns (FA1 and FA2) contain overhead bytes. The remaining 238 columns (2160 octets) are the payload. The overhead bytes are defined as follows: + +| | | | +|-----|-----|--------------------| +| FA1 | FA2 | 2160 octet payload | +| EM | P1 | | +| TR | P2 | | +| MA | | | +| NR | | | +| GC | | | +| | | | +| | | | +| | | | + +Not yet defined + +T1302730-94 + +Diagram of frame structure at 139 264 kbit/s showing 240 columns and 9 rows. The first two columns are overhead (FA1, FA2, EM, P1, TR, P2, MA, NR, GC) and the remaining 238 columns are the 2160 octet payload. A legend indicates that grey cells are 'Not yet defined'. + +Figure 2-5/G.832 – Frame structure at 139 264 kbit/s + +### 2.4.2 Overhead allocation + +The values and allocation of the overhead bytes are shown in Figure 2-6 and are described below. + +![Diagram of overhead allocation at 139 264 kbit/s showing a table of overhead bytes (FA1, EM, TR, MA, NR, GC) and their corresponding values or fields.](3ad00ce93ad9dea9ee0f47535e5355e6_img.jpg) + +| | | | | | | | | | | | | | | | | | | +|-----|-------------|-----|--------------|---|-----|---|-----|---|----|---|---|---|---|---|---|---|-----| +| FA1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | FA2 | +| EM | BIP-8 | | | | | | | | P1 | | | | | | | | P1 | +| TR | Trail Trace | | | | | | | | P2 | | | | | | | | P2 | +| MA | RDI | REI | Payload type | | MFI | | SSM | | | | | | | | | | | +| NR | NR | | | | | | | | | | | | | | | | | +| GC | GC | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | + +T1302740-94 + +Diagram of overhead allocation at 139 264 kbit/s showing a table of overhead bytes (FA1, EM, TR, MA, NR, GC) and their corresponding values or fields. + +Figure 2-6/G.832 – Overhead allocation at 139 264 kbit/s + +#### FA1/FA2 + +Frame Alignment signal. This has the same pattern as A1/A2 defined in Recommendation G.707. + +#### EM + +Error Monitoring, BIP-8. One byte is allocated for error monitoring. This function shall be a BIP-8 code using even parity. The BIP-8 is calculated over all bits of the previous 125 µs frame. The computed BIP-8 is placed in the EM byte of the current 125 µs frame. + +#### TR + +Trail Trace. This byte is used to repetitively transmit a trail access point identifier so that a trail receiving terminal can verify its continued connection to the intended transmitter. The trail access point identifier shall use the access point identifier format as defined in clause 3/G.831. + +A 16-byte frame is defined for the transmission of the access point identifier and this is described in Annex A. + +#### MA Maintenance and Adaptation byte + +Bit 1 RDI + +Bit 2 REI – This bit is set to "1" and sent back to the remote trail termination if one or more errors were detected by the BIP-8, and is otherwise set to zero. + +Bits 3 to 5 Payload type + +| Code | Signal | +|------|-------------------------------------------------| +| 000 | Unequipped | +| 001 | Equipped, non-specific | +| 010 | ATM | +| 011 | SDH elements mapping I 20 × TUG-2 | +| 100 | SDH elements mapping II 2 × TUG-3 and 5 × TUG-2 | + +Bits 6-7 Multiframe indicator + +Bit 8 This bit is used in a four-frame multiframe. The phase of the multiframe is determined by the value of MA bits 6 and 7, according to: + +| Bit 6 | Bit 7 | Bit 8 | +|-------|-------|-----------------| +| 0 | 0 | SSM bit 1 (MSB) | +| 0 | 1 | SSM bit 2 | +| 1 | 0 | SSM bit 3 | +| 1 | 1 | SSM bit 4 (LSB) | + +The four bits of the multiframe are allocated to the Synchronization Status Message (SSM). The coding of the SSM is given in Table 5/G.707. + +When interworking with "old" equipment which used bit 8 as a timing marker (non-multiframe), the "new" equipment implementing the above requirement should be capable of being configured to transmit the "old" requirement as given below: + +Bit 8, Timing marker. This bit is set to "0" to indicate that the timing source is traceable to a Primary Reference Clock, and is otherwise set to "1". + +#### **NR** + +Network Operator byte. This byte is allocated for maintenance purposes specific to individual Network Operators. Its transparency from Trail termination to Trail termination is not guaranteed. In the case where this byte is modified at an intermediate point in the trail, the EM byte must be appropriately corrected to ensure performance monitoring integrity. For Tandem Connection Maintenance, the byte is used in accordance with Annex D/G.707. + +#### **GC** + +General purpose communications channel (e.g. to provide data/voice channel connection for maintenance purposes). + +#### **P1/P2** + +Automatic Protection Switching. + +# **3 Multiplexing structures** + +## **3.1 Support of SDH elements in the 34 368 kbit/s frame structure** + +14 × TU-12s are arranged in the 530 octets payload area as shown in Figure 3-1. + +Columns one (except the first octet), thirty and thirty-one are occupied by fixed stuff, the 14 × TU-12s are 1-column interleaved into this structure and have a fixed phase relationship with respect to the frame structure. The Tributary Unit pointers occupy the octets in the first row from columns 2 to 15. + +![Figure 3-1/G.832 – Support of 14 TU-12s in the 34 368 kbit/s frame structure](ad29805cd4f64ad2828e14feb66de664_img.jpg) + +Figure 3-1/G.832 – Support of 14 TU-12s in the 34 368 kbit/s frame structure + +Figure 3-1/G.832 – Support of 14 TU-12s in the 34 368 kbit/s frame structure + +The TU-12 elements are defined in Recommendation G.707. + Figure 3-2 shows the multiplexing structure. + +![Figure 3-2/G.832 – Multiplexing route for the 34 368 kbit/s frame structure](b3df5964338063224492c01f09e4fed6_img.jpg) + +Figure 3-2/G.832 – Multiplexing route for the 34 368 kbit/s frame structure + +Figure 3-2/G.832 – Multiplexing route for the 34 368 kbit/s frame structure + +### 3.1.1 Coding of multiframe indicator for Tributary Unit multiframe indication + +Table 3-1 shows the coding of the multiframe indicator (bits 6 and 7 of the MA octet) in case of TU-12s mapping. + +10 Recommendation G.832 (10/98) + +**Table 3-1/G.832** + +| Bit 6 | Bit 7 | TU-PTR content in the following frame | +|-------|-------|---------------------------------------| +| 0 | 0 | V1 | +| 0 | 1 | V2 | +| 1 | 0 | V3 | +| 1 | 1 | V4 | + +500 ms Tributary Unit multiframe + +The relation between the TU-PTR content and the coding of the payload dependent bits is shown in Figures 8-13/G.707 and 8-14/G.707. + +## 3.2 Support of SDH elements in the 44 736 kbit/s frame structure + +A TU-12 consists of 144 bytes per 500 µs. 19 × TU-12s are arranged in the 2736 octets payload area of the intermediate 500 µs frame as shown in Figure 3-3. + +The Tributary Unit pointers occupy the octets in the first row from columns 2 to 20. + +Figure 3-4 shows the multiplexing structure. + +![Diagram showing the multiplexing of 19 TU-12s into the intermediate 500 µs frame structure. The diagram is a grid with 19 columns and 27 rows. The first row contains F1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1. The second row contains F2. The third row contains F3. The fourth row contains F4. The remaining 23 rows are empty. The number 1 is at the bottom left, and 19 is at the bottom right.](43837b056625d3d6ce615e4c02f163bb_img.jpg) + +Diagram showing the multiplexing of 19 TU-12s into the intermediate 500 µs frame structure. The diagram is a grid with 19 columns and 27 rows. The first row contains F1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1, V1. The second row contains F2. The third row contains F3. The fourth row contains F4. The remaining 23 rows are empty. The number 1 is at the bottom left, and 19 is at the bottom right. + +T1304190-95 + +**Figure 3-3/G.832 – Multiplexing of 19 TU-12s into the intermediate 500 µs frame structure for transport within the 44 736 kbit/s frame structure** + +![Figure 3-4/G.832 – Multiplexing route for the transport of SDH elements in the 44 736 kbit/s frame structure. The diagram shows a linear flow: VC-12 (with T1304200-95 label) → TU-12 → Intermediate 500 μs frame → 44 736 kbit/s DS3 signal. A legend indicates: Pointer processing (grey box), Aligning (dashed arrow), Mapping (solid arrow), and Multiplexing (solid arrow with a dot).](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Figure 3-4/G.832 – Multiplexing route for the transport of SDH elements in the 44 736 kbit/s frame structure. The diagram shows a linear flow: VC-12 (with T1304200-95 label) → TU-12 → Intermediate 500 μs frame → 44 736 kbit/s DS3 signal. A legend indicates: Pointer processing (grey box), Aligning (dashed arrow), Mapping (solid arrow), and Multiplexing (solid arrow with a dot). + +**Figure 3-4/G.832 – Multiplexing route for the transport of SDH elements in the 44 736 kbit/s frame structure** + +## 3.3 Support of SDH elements in the 97 728 kbit/s frame structure + +The 1522 octets payload capacity can be used to support two reduced VC-3s (VC-3Rs). The VC-3R can contain seven TUG-2s or one C-3 defined in Recommendation G.707. + +Figure 3-5 shows the multiplexing structure with the relevant lower level options. + +![Figure 3-5/G.832 – Multiplexing routes for the transport of SDH elements in the 97 728 kbit/s frame structure. The diagram shows a hierarchical flow: VC-2, VC-12, and VC-11 → TU-2, TU-12, and TU-11 → TUG-2 → VC-3R → 97 728 kbit/s. C-3 also feeds into VC-3R. Multiplication factors (× 1, × 3, × 4, × 7, × 2) are shown on the multiplexing arrows. A legend indicates: C-3 (Container of level 3), Pointer processing (grey box), Multiplexing (solid arrow with a dot), Aligning (dashed arrow), Mapping (solid arrow), and Aligning and multiplexing (dashed arrow with a dot).](9cd90f495b95ad2116ff780248c26d95_img.jpg) + +Figure 3-5/G.832 – Multiplexing routes for the transport of SDH elements in the 97 728 kbit/s frame structure. The diagram shows a hierarchical flow: VC-2, VC-12, and VC-11 → TU-2, TU-12, and TU-11 → TUG-2 → VC-3R → 97 728 kbit/s. C-3 also feeds into VC-3R. Multiplication factors (× 1, × 3, × 4, × 7, × 2) are shown on the multiplexing arrows. A legend indicates: C-3 (Container of level 3), Pointer processing (grey box), Multiplexing (solid arrow with a dot), Aligning (dashed arrow), Mapping (solid arrow), and Aligning and multiplexing (dashed arrow with a dot). + +NOTE – The VC-3R is a VC-3 SDH element with reduced functionality as shown in Figure 2-4. + +**Figure 3-5/G.832 – Multiplexing routes for the transport of SDH elements in the 97 728 kbit/s frame structure** + +## 3.4 Support of SDH elements in the 139 264 kbit/s frame structure + +The 2160 octets payload capacity can be used to support the following multiplexing options: + +- Option I – $20 \times$ TUG-2; +- Option II – $2 \times$ TUG-3 and $5 \times$ TUG-2. + +The TUG-2 and the TUG-3 are defined in Recommendation G.707. + +Figure 3-6 shows the two TUG multiplexing opportunities with the relevant lower level structure. + +![Diagram showing multiplexing routes for SDH elements into the 139 264 kbit/s frame structure. The diagram illustrates two options: Option I (20 x TUG-2) and Option II (2 x TUG-3 and 5 x TUG-2).](898fb89a50d9ec1dfb4e425c816976a7_img.jpg) + +The diagram illustrates the multiplexing hierarchy for SDH elements into a 139 264 kbit/s frame. At the top, a box labeled '139 264 kbit/s' is connected to a multiplexing point (indicated by a black wedge). Two options are shown: + +- Option I:** A solid line labeled $\times 20$ leads from the multiplexing point to a TUG-2 box. From the TUG-2 box, four solid lines lead to TU-11, TU-12, TU-2, and TU-3 boxes, labeled $\times 4$ , $\times 3$ , $\times 1$ , and $\times 1$ respectively. Each TU box is connected to a corresponding VC box (VC-11, VC-12, VC-2, VC-3) by a dotted line (aligning). The TU-3 box is also connected to the top multiplexing point by a solid line labeled $\times 2$ . +- Option II:** A solid line labeled $\times 2$ leads from the top multiplexing point to a TUG-3 box. From the TUG-3 box, a solid line labeled $\times 5$ leads to the TUG-2 box. The TUG-2 box then branches out to the same TU and VC hierarchy as in Option I. Additionally, a solid line labeled $\times 7$ leads from the TUG-3 box directly to the top multiplexing point. + +Legend: + +- Pointer processing (grey box) +- Multiplexing of non-homogeneous signals (black wedge) +- Multiplexing (solid line with arrow) +- Aligning (dotted line with arrow) + +T1302780-94 + +Diagram showing multiplexing routes for SDH elements into the 139 264 kbit/s frame structure. The diagram illustrates two options: Option I (20 x TUG-2) and Option II (2 x TUG-3 and 5 x TUG-2). + +**Figure 3-6/G.832 – Multiplexing routes for the transport of SDH elements into the 139 264 kbit/s frame structure** + +### 3.4.1 Multiplexing of $20 \times$ TUG-2 + +The arrangement of $20$ TUG-2s multiplexed into the 9 rows by 240 columns payload is shown in Figure 3-7. The $20$ TUG-2s are one-byte interleaved into this structure and have a fixed phase relationship with respect to the frame overhead. + +![Diagram showing the multiplexing of 20 TUG-2 units into a larger payload structure. At the top, three boxes represent TUG-2 #1, TUG-2 #2, and TUG-2 #20, each with 12 columns. Below them, a long horizontal bar represents the multiplexed payload, divided into sections: OH, columns 1-5, a gap, columns 18-20, columns 1-3, another gap, columns 18-20, and a final gap. Lines connect the 12 columns of each TUG-2 to specific positions in the multiplexed bar: TUG-2 #1 connects to 1-5 and 18-20; TUG-2 #2 connects to 1-3 and 18-20; TUG-2 #20 connects to 18-20. Below the bar, column indices are listed: 1, 2, 3, 4, 5, ..., 18, 19, 20, 21, 22, 23, ..., 238, 239, 240. A small code 'T1304210-95' is at the bottom right.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +Diagram showing the multiplexing of 20 TUG-2 units into a larger payload structure. At the top, three boxes represent TUG-2 #1, TUG-2 #2, and TUG-2 #20, each with 12 columns. Below them, a long horizontal bar represents the multiplexed payload, divided into sections: OH, columns 1-5, a gap, columns 18-20, columns 1-3, another gap, columns 18-20, and a final gap. Lines connect the 12 columns of each TUG-2 to specific positions in the multiplexed bar: TUG-2 #1 connects to 1-5 and 18-20; TUG-2 #2 connects to 1-3 and 18-20; TUG-2 #20 connects to 18-20. Below the bar, column indices are listed: 1, 2, 3, 4, 5, ..., 18, 19, 20, 21, 22, 23, ..., 238, 239, 240. A small code 'T1304210-95' is at the bottom right. + +**Figure 3-7/G.832 – Multiplexing of 20 × TUG-2 into the 139 264 kbit/s payload capacity** + +### 3.4.2 Multiplexing of 2 × TUG-3 and 5 × TUG-2 + +The arrangement of 2 TUG-3s and 5 TUG-2s multiplexed into the 9 rows by 240 columns payload is shown in Figure 3-8. + +As a first step, four fixed stuff columns are added to each TUG-3 structure in the leading positions, resulting in two 90 column structures ("A" and "B"). The 5 TUG-2s are one-byte interleaved to a 60 columns by 9 rows structure ("C"). + +These three intermediate structures are then byte interleaved in the following sequence: + +$$[ABACBABC]_1 \quad [ABACBABC]_2 \dots \dots \dots [ABACBABC]_{30}$$ + +If further interworking flexibility is required, this arrangement could also be further demultiplexed into one TUG-3 and 12 (7 + 5) TUG-2s or all TUG-2s in which case a maximum of 19 TUG-2s can be carried. If only TUG-2s are required, this last situation is unlikely as the arrangement described in 3.4.1 provides for 20 TUG-2s. + +![Diagram showing the multiplexing of 2 TUG-3 and 5 TUG-2 tributary units into a 139 264 kbit/s payload capacity. The diagram illustrates the mapping of TUG-3 #1, TUG-3 #2, and five TUG-2 units into a large frame structure. TUG-3 units are shown with 86 columns and 4 fixed stuff columns. TUG-2 units are shown with 12 columns and 1 fixed stuff column. The bottom section shows the mapping of these units into a 240-column frame, with specific columns labeled A, B, and C. The total payload capacity is indicated as 139 264 kbit/s.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +Diagram showing the multiplexing of 2 TUG-3 and 5 TUG-2 tributary units into a 139 264 kbit/s payload capacity. The diagram illustrates the mapping of TUG-3 #1, TUG-3 #2, and five TUG-2 units into a large frame structure. TUG-3 units are shown with 86 columns and 4 fixed stuff columns. TUG-2 units are shown with 12 columns and 1 fixed stuff column. The bottom section shows the mapping of these units into a 240-column frame, with specific columns labeled A, B, and C. The total payload capacity is indicated as 139 264 kbit/s. + +**Figure 3-8/G.832 – Multiplexing of 2 × TUG-3 and 5 × TUG-2 into the 139 264 kbit/s payload capacity** + +### **3.4.3 Coding of multiframe indicator for Tributary Unit multiframe indication** + +Table 3-2 shows the coding of the multiframe indicator (bits 6 and 7 of the MA octet) in the case of TU-1xs mapping. + +**Table 3-2/G.832** + +| Bit 6 | Bit 7 | TU-PTR content in the following frame | | +|-------|-------|---------------------------------------|----------------------------------| +| 0 | 0 | V1 | | +| 0 | 1 | V2 | | +| 1 | 0 | V3 | | +| 1 | 1 | V4 | 500 ms Tributary Unit multiframe | + +The relation between the TU-PTR content and the coding of the payload dependent bits is shown in Figures 8-13/G.707 and 8-14/G.707. + +# ANNEX A + +## Description of the 16-byte frame and CRC-7 calculation + +The first byte of the string is a frame start marker and includes the result of a CRC-7 calculation over the previous frame. The following 15 bytes are used for the transport of 15 T.50 characters (international reference version) required for the access point identifier. The 16-byte frame is given below: + +| | | | | | | | | | +|---|----------------|---|---|---|---|---|----------------|--------------------| +| 1 | C 1 | C | C | C | C | C | C 7 | Frame start marker | +| 0 | X | X | X | X | X | X | X | byte 2 | +| | | | | | | | | | +| | | | | | | | | | +| | | | | | | | | | +| 0 | X | X | X | X | X | X | X | byte 16 | + + + +| | | | | | | | | +|----------------|---|---|---|---|---|----------------|---------------------------------------------------------| +| X | X | X | X | X | X | X | T.50 character | +| C 1 | C | C | C | C | C | C 7 | Result of the CRC-7 calculation over the previous frame | + +The description of the CRC-7 calculation is given below: + +### Multiplication/division process + +A particular CRC-7 word is the remainder after multiplication by $x^7$ and the division (modulo 2) by the generator polynomial $x^7 + x^3 + 1$ , of the polynomial representation of the previous Trail Trace Identifier (TTI) multiframe. + +When representing the contents of the block as a polynomial, the first bit in the block, i.e. byte 1, bit 1 should be taken as being the most significant bit. Similarly, C1 is defined to be the most significant bit of the remainder and C7 to be the least significant bit of the remainder. + +### Encoding procedure + +The CRC-7 word is static because the data is static (the TTI represents the source address). This means that the CRC-7 checksum can be calculated either over the previous multiframe or *a priori*. In the last case this means that the 16-byte string that is loaded in a device for repetitive transmission should have the calculated checksum in the correct position. + +The encoding procedure is as follows: + +- The CRC-7 bits in the TTI are replaced by binary 0s. +- The TTI is then acted upon by the multiplication/division process referred to above. +- The remainder resulting from the multiplication/division process is inserted into the CRC-7 location. + +The CRC-7 bits generated do not affect the result of the multiplication process because, as indicated in i) above, the CRC-7 bit positions are initially set to 0 during the multiplication/division process. + +### **Decoding procedure** + +- i) A received TTI is acted upon by the multiplication/division process referred to above after having its CRC-7 bits extracted and replaced by 0s. +- ii) The remainder resulting from the division process is then compared on a bit-by-bit basis with the CRC-7 bits received. +- iii) If the remainder calculated in the decoder exactly corresponds to the CRC-7 bits received, it is assumed that the received TTI is error free. + + + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure | +| Series Z | Programming languages | \ No newline at end of file diff --git a/marked/G/T-REC-G.852.8-199903-I_PDF-E/raw.md b/marked/G/T-REC-G.852.8-199903-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..e481bc9cf9c7535e0d89fc97cbc6e42306574b76 --- /dev/null +++ b/marked/G/T-REC-G.852.8-199903-I_PDF-E/raw.md @@ -0,0 +1,472 @@ + + +![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with the letters ITU and a lightning bolt. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.852.8** + +(03/99) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – +Management of transport network + +--- + +**Enterprise viewpoint for pre-provisioned +adaptation management** + +ITU-T Recommendation G.852.8 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +# **ENTERPRISE VIEWPOINT FOR PRE-PROVISIONED ADAPTATION MANAGEMENT** + +## **Summary** + +The pre-provisioned adaptation management service allows to assign a server transport entity (trail or trail termination point) to a client linking entity (topological link or topological link end). This service allows for provision/remove client transport entities (link connections or connection termination points) to/from server linking entities (topological link or topological link end). A notification service is also made available for any changes made as consequence of actions in this community. + +## **Source** + +ITU-T Recommendation G.852.8 was prepared by ITU-T Study Group 4 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 26th of March 1999. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +###### Page + +| | | | +|-------|---------------------------------------------------------|---| +| 1 | Scope ..... | 1 | +| 2 | References ..... | 1 | +| 3 | Definitions ..... | 1 | +| 4 | Abbreviations ..... | 1 | +| 5 | Conventions ..... | 1 | +| 6 | Community "pre-provisioned adaptation management" ..... | 2 | +| 6.1 | Purpose ..... | 2 | +| 6.2 | Role ..... | 2 | +| 6.2.1 | Community ..... | 3 | +| 6.2.2 | Action ..... | 3 | + + + +###### Recommendation G.852.8 + +# ENTERPRISE VIEWPOINT FOR PRE-PROVISIONED ADAPTATION MANAGEMENT + +(Geneva, 1999) + +# 1 Scope + +This Recommendation specifies the enterprise viewpoint for the pre-provisioned adaptation management of a transport network. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.851.1 (1996), *Management of the transport network – Application of the RM-ODP framework*. +- [2] ITU-T Recommendation G.852.2 (1999), *Enterprise viewpoint description of transport network resource model*. + +# 3 Definitions + +None. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +- LC Link Connection +- pam pre-provisioned adaptation management +- SDH Synchronous Digital Hierarchy +- TEM Transport Enterprise Model +- tu tributary unit +- WDM Wavelength Division Multiplexing + +# 5 Conventions + +None. + +# 6 Community "pre-provisioned adaptation management" + +## 6.1 Purpose + +The objective of this community is to provide link capacity to client-layer(s) from a server layer. This community should be used in the case where client transport entities can be provisioned inside the link during the adaptation management. This capability of having pre-provisioned client transport entities is available in technologies such as SDH or WDM. + +The management of compound links and diverse routing is not addressed in this community. + +## 6.2 Role + +### **pam\_caller** + +This role reflects the client of the actions defined within this community. One and only one caller role occurrence must exist in the community. + +### **pam\_provider** + +This role reflects the server of the actions defined within this community. One and only one provider role occurrence must exist in the community. + +### **notification receiver** + +This role represents a receiver of the reporting actions defined within this community. Zero or more notification receiver role occurrences may exist in the community. + +### **client layer network domain** + +This role reflects the layer network Domain defined in Recommendation G.852.2 that contains the client linking entities having the same signal identification. One or more occurrences may exist in the community. + +### **server layer network domain** + +This role reflects the layer network Domain defined in Recommendation G.852.2 that contains the serve linking entities. One and only one occurrence must exist in the community. + +### **client linking entity** + +This role reflects either the topological link resource or the topological link end resource as defined in Recommendation G.852.2. One client linking entity role occurrence per layer served by the layer of the client transport entity role occurrence may exist in the community. + +### **client transport entity** + +This role reflects either the link connection resource or the network connection termination point resource as defined in Recommendation G.852.2. Zero or more client transport entity role occurrences may exist in the community. + +#### **server transport entity** + +This role reflects either the trail resource or the network trail termination point resource as defined in Recommendation G.852.2. One or more server transport entity role occurrences may exist in the community. + +### **6.2.1 Community** + +#### **OBLIGATION resourceConsistency** + +This community applies for both arc-oriented view and point-oriented view. Roles client linking entity, client transport entity and server transport entity can be played by either an arc-oriented resource or a point-oriented resource, but consistently: those three roles can be played either by arc-oriented resources or by point-oriented resources, but not by a mixture of arc-oriented and point-oriented resources. + +#### **OBLIGATION scope** + +Only properties that are explicitly stated in this community are valid and can be accessed by both caller and provider of this community. Conformance to this service depends only on the explicit specification of this service. Any other modifications outside of this community is not relevant for conformance. + +##### **OBLIGATION serviceRejection** + +In this community, a provider shall identify the obligation or prohibition which is not fulfilled either by the caller or the provider. The provider shall give an indication about any execution infrastructure problem. In this case, the level of detail indicated by the provider shall be dependent on shared the knowledge of the infrastructure on which the community is running. If the rejection is due to incorrect caller behaviour or information, the provider has to give it back enough indication to allow for correction. + +#### **OBLIGATION viewingCapabilities** + +The provider shall support such viewing of the resource properties and relationships that have been identified or permitted in the service contract with the caller. + +#### **OBLIGATION belongingConstraints** + +All resources managed in the community actions shall belong to the community. + +#### **OBLIGATION consistentClientAndServerSignalId** + +The signal identification of the resources playing the roles client linking entity and client transport entity should correspond to a layer which is client of the layer characterized by the signal identification of the resources playing the role server transport entity. + +#### **OBLIGATION architecturalConstraints** + +All the modifications performed on the resources in this community are done in respect with the architectural constraints expressed in Recommendation G.852.2 (TEM). + +### **6.2.2 Action** + +#### **6.2.2.1 Assign server transport entity to client linking entity** + +This action is used to assign a server transport entity to a client linking entity. Those two entities are provided by the caller. The provider shall report the potential number of client transport entities of the client linking entity in case of success. + +![Diagram showing two client layers (A and B) connected to a common server layer via a trail. Each client layer has a link (LINK) that is connected to the trail. The diagram illustrates a trail serving two links in two different client layers.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +The diagram shows a 'server layer' at the bottom, represented by a solid horizontal line labeled 'TRAIL'. Above this are two 'client layers', 'client layer A' and 'client layer B', each represented by a dashed horizontal line. In 'client layer A', there is a 'LINK' entity, depicted as a horizontal cylinder. An arrow points from the 'TRAIL' line up to this 'LINK'. Similarly, in 'client layer B', there is another 'LINK' entity, also represented by a horizontal cylinder, with an arrow pointing from the 'TRAIL' line up to it. A vertical dashed line separates the two client layers. + +Diagram showing two client layers (A and B) connected to a common server layer via a trail. Each client layer has a link (LINK) that is connected to the trail. The diagram illustrates a trail serving two links in two different client layers. + +Example of a trail serving 2 links in two different client layers + +T0410670-98 + +##### **ACTION\_POLICY** + +###### **OBLIGATION** inputClientLinkingEntityId + +The caller shall provide the identifier of the client linking entity that must not be already associated to a server transport entity. + +###### **OBLIGATION** inputServerTransportEntityId + +The caller shall provide the identifier of the server transport entity. + +##### **PERMISSION** returnClientTransportEntities + +The provider may return the identifiers of the client transport entities that are already supported by the server transport entity. This is to cover the case where the adaptation is fixed and all the client transport entities have been already provisioned during the creation of the server transport entity. + +###### **OBLIGATION** successReturnUnprovisionedCapacity + +In case of a successful action, the provider shall return to the caller the number of unprovisioned client transport entities of the client linking entity. + +#### **6.2.2.2 Deassign server transport entity from client linking entity** + +This action is used to deassign the transport entity from a client linking entity. The client linking entity is identified by the caller. The provider shall reject the request if some capacity is still provided by the transport entity to the client linking entity. + +##### **ACTION\_POLICY** + +###### **OBLIGATION** inputClientLinkingEntityId + +The caller shall provide the identifier of the client linking entity. + +###### **OBLIGATION** inputServerTransportEntityId + +The caller shall provide the identifier of the server transport entity. + +###### **OBLIGATION** noProvidedCapacity + +The provider shall reject the request if the server transport entity is still providing capacity to the client linking entity. + +###### **OBLIGATION** successReturn + +In case of a successful action, the provider shall indicate to the caller that the action was successful. + +#### 6.2.2.3 Provision capacity to client linking entity + +This action is used to provision a capacity in terms of a number of client transport entities from the server transport entity to a client linking entity. In case of a successful action, the capacity requested by the caller is provisioned and added to the previous provisioned number of client transport entities of the client linking entity and the provisioned client transport entities are returned. The caller has the ability to specify the channels (timeslots for SDH) of the client transport entities that shall be provisioned. The provider shall not satisfy the request if the requested capacity is larger than the potential capacity of the client linking entity and it has the responsibility to manage the remaining number of client transport entities so that the whole capacity is made available to all the client linking entities. + +![Diagram illustrating a server trail providing capacity to two different client linking entities. The diagram shows a horizontal line at the bottom labeled 'TRAIL'. Above it, a dashed line represents the 'server layer: VC4'. Two client layers are shown above the server layer: 'client layer VC12' on the left and 'client layer VC3' on the right. The VC12 layer is connected to the trail by a dashed line and is labeled 'Provisioned capacity: 21 TU12 LC'. The VC3 layer is also connected to the trail by a dashed line and is labeled 'Provisioned capacity: 2 TU3 LC'. A vertical dashed line separates the two client layers.](e9314c83043183351ed74908e9bf2f90_img.jpg) + +Diagram illustrating a server trail providing capacity to two different client linking entities. The diagram shows a horizontal line at the bottom labeled 'TRAIL'. Above it, a dashed line represents the 'server layer: VC4'. Two client layers are shown above the server layer: 'client layer VC12' on the left and 'client layer VC3' on the right. The VC12 layer is connected to the trail by a dashed line and is labeled 'Provisioned capacity: 21 TU12 LC'. The VC3 layer is also connected to the trail by a dashed line and is labeled 'Provisioned capacity: 2 TU3 LC'. A vertical dashed line separates the two client layers. + +Example of a server trail providing 21 TU12 and 2 TU3 to two different links + +T0410680-98 + +##### ACTION\_POLICY + +**OBLIGATION** inputClientLinkingEntityId + +The caller shall provide the identifier of the client linking entity. + +**PERMISSION** selectClientTransportEntities + +The caller may provide the channels (timeslots for SDH) of the client transport entities that shall be provisioned. + +**OBLIGATION** providerClientTransportEntities + +If **PERMISSION** selectClientTransportEntities is part of the contracted service, then the provider shall provision the client transport entities specified by the caller. + +**OBLIGATION** correctChannels + +If **PERMISSION** selectClientTransportEntities is part of the contracted service and if the channels specified are not correct (e.g. already provisioned or not allowed according to the concerned technology), then the provider shall reject the action. + +**OBLIGATION** inputRequestedCapacity + +If **PERMISSION** selectClientTransportEntities is not part of the service contract, the caller shall provide the requested number of client transport entities. + +**OBLIGATION** consistency + +The provider shall reject the request if the number of client transport entities requested for the client linking entity exceeds the potential number of client transport entities. The provider shall inform the caller of the maximum number of client transport entities that could be provisioned. + +###### OBLIGATION multipleClientLinkingEntityProvisioning + +The provider shall ensure that the unrequested part of the server transport entity capacity is made available for all the other client linking entities supported. For example in SDH technology, if only 21 tu12 of a vc4 trail are provided to the caller, the provider shall ensure that the remaining capacity is made available to other client linking entities supported by the trail (e.g. in the vc3 link two tu3). + +###### OBLIGATION deduceProvisionedCapacity + +In case of a successful action, the provider shall deduce the new provisioned number of client transport entities of the client linking entity as follows: the new provisioned number of client transport entities is equal to the previous provisioned number of client transport entities of the client linking entity plus the capacity newly provisioned by this action. + +###### OBLIGATION successReturnCapacity + +In case of a successful action, the provider shall return the new provisioned number of client transport entities of the client linking entity. + +###### OBLIGATION successReturnClientTransportEntitiesId + +In case of a successful action, the provider shall return the identifiers of the provisioned client transport entities. There shall be a relationship between those identifiers and the channels (timeslots for SDH) of the provisioned client transport entities. + +#### **6.2.2.4 Remove capacity from client linking entity** + +This action is used to remove capacity from a client linking entity. In case of success, the capacity provided by the caller is removed and deduced from the previous available number of client transport entities of the client linking entity and the deleted client transport entities are returned. The provider shall not satisfy the request if the requested number of client linking entities is larger than the available number of client transport entities. The provider has the responsibility to manage the remaining number of client transport entities so that the whole capacity is made available to the client linking entities. + +##### **ACTION\_POLICY** + +###### OBLIGATION inputClientLinkingEntityId + +The caller shall provide the identifier of the client linking entity. + +###### PERMISSION selectClientTransportEntities + +The caller may provide the channels (timeslots for SDH) of the client transport entities that shall be removed. + +###### OBLIGATION providerClientTransportEntities + +If PERMISSION selectClientTransportEntities is part of the contracted service, then the provider shall remove the client transport entities specified by the caller. + +###### OBLIGATION correctChannels + +If PERMISSION selectClientTransportEntities is part of the contracted service and if the channels specified are not provisioned, then the provider shall reject the action. + +###### OBLIGATION inputRequestedCapacity + +If PERMISSION selectClientTransportEntities is not part of the service contract, the caller shall provide the number of client transport entities to be removed. + +###### OBLIGATION multipleClientLinkingEntityProvisioning + +The provider shall ensure that the unrequested part of the server transport entity capacity is made available for all the other client linking entities supported. For example in SDH technology, if only 21 tu12 of a vc4 trail are provided to the caller, the provider shall ensure that the remaining capacity is made available to other client linking entities supported by the trail (e.g. in the vc3 link two tu3). + +###### OBLIGATION availableCapacity + +This action shall be rejected if the available number of client transport entities of the client linking entity is lower than the number of client transport entities to be removed. + +###### OBLIGATION deleteExistingClientTransportEntities + +In case of a successful action, the provider shall return the identifiers of the deleted client transport entities. + +###### OBLIGATION deduceProvisionedCapacity + +In case of a successful action, the provider shall deduce the new provisioned number of client transport entities of the client linking entity as follows: the new provisioned number of client transport entities is equal to the previous provisioned number of client transport entities of the client linking entity minus the capacity newly removed by this action. + +###### OBLIGATION successReturnCapacity + +In case of a successful action, the provider shall return the remaining provisioned number of client transport entities of the client linking entity. + +#### **6.2.2.5 Report assignment of server transport entity** + +This action is used to report the assignment of a server transport entity to a client linking entity. The client linking entity and the server transport entity assigned to it shall be notified by the provider. + +##### **ACTION\_POLICY** + +###### OBLIGATION informClientLinkingEntity + +The notification receiver shall be informed by the provider of the identifier of the client linking entity. + +###### OBLIGATION informServerTransportEntity + +The notification receiver shall be informed by the provider of the identifier of the server transport entity assigned to the client linking entity. + +#### **6.2.2.6 Report deassignment of server transport entity** + +This action is used to report the deassignment of the server transport entity from a client linking entity. + +##### **ACTION\_POLICY** + +###### OBLIGATION informClientLinkingEntity + +The notification receiver shall be informed by the provider of the identifier of the client linking entity. + +###### OBLIGATION informServerTransportEntity + +The notification receiver shall be informed by the provider of the identifier of the server transport entity deassigned from the client linking entity. + +#### **6.2.2.7 Report client linking entity capacity provisioning** + +This action is used by the provider to report on the provisioning of a number of client transport entities to a client linking entity. + +##### **ACTION\_POLICY** + +OBLIGATION informClientLinkingEntity + +The notification receiver shall be informed by the provider of the identifier of the client linking entity. + +OBLIGATION informCapacityProvided + +The notification receiver shall be informed by the provider of the number of client transport entities provided. + +OBLIGATION informChannelsProvided + +The notification receiver shall be informed by the provider of the provided channels. + +#### **6.2.2.8 Report client linking entity capacity removal** + +This action is used by the provider to report on the removal of a number of client transport entities from a client linking entity. + +##### **ACTION\_POLICY** + +OBLIGATION informClientLinkingEntity + +The notification receiver shall be informed by the provider of the identifier of the client linking entity. + +OBLIGATION informCapacityRemoved + +The notification receiver shall be informed by the provider of the number of client transport entities removed. + +OBLIGATION informChannelsRemoved + +The notification receiver shall be informed by the provider of the removed channels. + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.853.16-200101-I_PDF-E/raw.md b/marked/G/T-REC-G.853.16-200101-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..c974ca845e031dcec03dd8e4c17e7e9893137d9a --- /dev/null +++ b/marked/G/T-REC-G.853.16-200101-I_PDF-E/raw.md @@ -0,0 +1,739 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. A lightning bolt symbol is positioned to the right of the globe. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.853.16** + +(01/2001) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital networks – Management of transport network + +--- + +**Information viewpoint for pre-provisioned route +discovery** + +ITU-T Recommendation G.853.16 + +(Formerly CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS + +## TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +For further details, please refer to the list of ITU-T Recommendations. + +# **Information viewpoint for pre-provisioned route discovery** + +# **Summary** + +The route discovery service identifies routes for trails, tandem connections or subnetwork connections with or without protection in a layer network. It is possible to request conditions that have to be met by the identified route. In addition to proposing routes, information is provided to help in the selection among the candidate routes on the basis of a set of properties. + +A service for the notification of external notification receivers of the identified routes is provided as well. + +### **Source** + +ITU-T Recommendation G.853.16 was prepared by ITU-T Study Group 4 (2001-2004) and approved under the WTSA Resolution 1 procedure on 19 January 2001. + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2001 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. + +# CONTENTS + +###### Page + +| | | | +|------|--------------------------------------------------------------------|---| +| 1 | Summary ..... | 1 | +| 2 | Scope..... | 1 | +| 3 | References..... | 1 | +| 4 | Definitions ..... | 1 | +| 5 | Abbreviations..... | 1 | +| 6 | Conventions ..... | 2 | +| 7 | Class diagrams ..... | 2 | +| 7.1 | UML class diagram representing the inheritance hierarchy ..... | 2 | +| 7.2 | UML class diagram representing relationships between classes ..... | 4 | +| 8 | Label references ..... | 5 | +| 9 | Information object class definitions..... | 5 | +| 9.1 | prdAccessGroup..... | 5 | +| 9.2 | prdLayerNetworkDomain..... | 5 | +| 9.3 | prdLink..... | 6 | +| 9.4 | prdLinkConnection ..... | 6 | +| 9.5 | prdLinkEnd ..... | 6 | +| 9.6 | prdNetworkCTP..... | 6 | +| 9.7 | prdNetworkTTP ..... | 6 | +| 9.8 | prdRoute..... | 7 | +| 9.9 | prdRouteSet ..... | 7 | +| 9.10 | prdRoutingConditions..... | 7 | +| 9.11 | prdSubnetwork..... | 8 | +| 9.12 | prdTopologicalLink ..... | 8 | +| 9.13 | prdTopologicalLinkEnd..... | 8 | +| 10 | Information relationship definitions ..... | 8 | +| 10.1 | prdRouteSetFulfillsRoutingConditions ..... | 8 | +| 10.2 | PrdRouteSetHasRoutes ..... | 9 | +| 11 | Static schemas ..... | 9 | +| 12 | Dynamic schemas ..... | 9 | +| 13 | Attributes ..... | 9 | +| 13.1 | prdArc-Point-orientedRouteComponents ..... | 9 | +| 13.2 | prdReturnedProperties ..... | 9 | +| 13.3 | prdRouteEnds..... | 9 | + +# **Information viewpoint for pre-provisioned route discovery** + +# **1 Summary** + +The route discovery service identifies routes for trails, tandem connections or subnetwork connections with or without protection in a layer network. It is possible to request conditions that have to be met by the identified route. In addition to proposing routes information is provided to help in the selection among the candidate routes, on the basis of a set of properties. + +A service for the notification of external notification receivers of the identified routes is provided as well. + +# **2 Scope** + +This information viewpoint specification is related to the pre-provisioned route discovery enterprise specification defined in ITU-T G.852.16. + +# **3 References** + +The following ITU-T Recommendations, and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T G.851.1 (1996), *Management of the transport network – Application of the RM-ODP framework.* +- [2] ITU-T G.853.1 (1999), *Common elements of the information viewpoint for the management of a transport network.* +- [3] ITU-T G.852.16 (2001), *Management of the transport network – Enterprise viewpoint for pre-provisioned route discovery.* +- [4] ITU-T G.853.10 (1999), *Management of the transport network – Information viewpoint for pre-provisioned link connection management.* + +# **4 Definitions** + +No new term is defined in this Recommendation. + +# **5 Abbreviations** + +This Recommendation uses the following abbreviations: + +| | | +|-------|----------------------------------------------------------------------------------| +| CTP | Connection Termination Point | +| Id | Identifier | +| imp | imported | +| ITU-T | International Telecommunication Union – Telecommunication Standardization Sector | + +| | | +|--------|-------------------------------------------------| +| LND | Layer Network Domain | +| plcm | Pre-Provisioned Link Connection Management | +| prd | Pre-provisioned route discovery | +| Rec. | Recommendation | +| RM-ODP | Reference Model for Open Distributed Processing | +| TTP | Trail Termination Point | +| UML | Unified Modelling Language | + +# **6 Conventions** + +None. + +# **7 Class diagrams** + +## **7.1 UML class diagram representing the inheritance hierarchy** + +![Inheritance diagram for Pre-provisioned Route Discovery (G.853.16).](3121ebddccf183ca63bb9781be440a7e_img.jpg) + +``` + +classDiagram + class G853_1_networkInformationTop { + resourceId + } + class G853_1_accessGroup { + signalIdentification + topologicalEndDirection + } + class prdAccessGroup + class G853_1_link { + signalIdentification + linkDirectionality + } + class prdLink + class G853_1_networkTTP { + signalIdentification + pointDirectionality + } + class prdNetworkTTP + class G853_1_topologicalLinkEnd { + signalIdentification + topologicalEndDirection + } + class prdTopologicalLinkEnd + class G853_1_linkEnd { + signalIdentification + topologicalEndDirection + } + class prdLinkEnd + class G853_1_topologicalLink { + signalIdentification + linkDirectionality + } + class prdTopologicalLink + class prdRouteSet { + prdRouteEnds + } + class G853_1_layerNetworkDomain { + signalIdentification + } + class prdLayerNetworkDomain + class G853_1_transportConnection { + signalIdentification + directionality + } + class G853_1_networkCTP { + signalIdentification + pointDirectionality + } + class prdRoutingConditions { + prdArc-Point-orientedRouteComponents + } + class G853_1_subnetwork { + signalIdentification + } + class prdSubnetwork + class prdRoute { + prdIndividualRouteComponentsList + prdReturnedProperties + } + class G853_1_10_plcmLinkConnection { + userLabel (imp) + plcmCallerId + } + class G853_1_10_plcmNetworkCTP { + userLabel (imp) + plcmCallerId + } + class prdLinkConnection + class prdNetworkCTP + + G853_1_networkInformationTop <|-- G853_1_accessGroup + G853_1_networkInformationTop <|-- G853_1_link + G853_1_networkInformationTop <|-- G853_1_networkTTP + G853_1_networkInformationTop <|-- G853_1_topologicalLinkEnd + G853_1_networkInformationTop <|-- G853_1_linkEnd + G853_1_networkInformationTop <|-- G853_1_topologicalLink + G853_1_networkInformationTop <|-- prdRouteSet + + G853_1_accessGroup <|-- prdAccessGroup + G853_1_link <|-- prdLink + G853_1_networkTTP <|-- prdNetworkTTP + G853_1_topologicalLinkEnd <|-- prdTopologicalLinkEnd + G853_1_linkEnd <|-- prdLinkEnd + G853_1_topologicalLink <|-- prdTopologicalLink + + G853_1_layerNetworkDomain <|-- prdLayerNetworkDomain + G853_1_transportConnection <|-- G853_1_10_plcmLinkConnection + G853_1_networkCTP <|-- G853_1_10_plcmNetworkCTP + prdRoutingConditions <|-- prdRoute + G853_1_subnetwork <|-- prdSubnetwork + + G853_1_10_plcmLinkConnection <|-- prdLinkConnection + G853_1_10_plcmNetworkCTP <|-- prdNetworkCTP + +``` + +The diagram illustrates the inheritance hierarchy for Pre-provisioned Route Discovery (G.853.16). At the top is **G.853.1:networkInformationTop** with attribute **resourceId**. It inherits from **G.853.1:accessGroup**, **G.853.1:link**, **G.853.1:networkTTP**, **G.853.1:topologicalLinkEnd**, **G.853.1:linkEnd**, **G.853.1:topologicalLink**, and **prdRouteSet**. +**G.853.1:accessGroup** (attributes: **signalIdentification**, **topologicalEndDirection**) inherits from **prdAccessGroup**. +**G.853.1:link** (attributes: **signalIdentification**, **linkDirectionality**) inherits from **prdLink**. +**G.853.1:networkTTP** (attributes: **signalIdentification**, **pointDirectionality**) inherits from **prdNetworkTTP**. +**G.853.1:topologicalLinkEnd** (attributes: **signalIdentification**, **topologicalEndDirection**) inherits from **prdTopologicalLinkEnd**. +**G.853.1:linkEnd** (attributes: **signalIdentification**, **topologicalEndDirection**) inherits from **prdLinkEnd**. +**G.853.1:topologicalLink** (attributes: **signalIdentification**, **linkDirectionality**) inherits from **prdTopologicalLink**. +**prdRouteSet** (attribute: **prdRouteEnds**) is a standalone class. +**G.853.1:layerNetworkDomain** (attribute: **signalIdentification**) inherits from **prdLayerNetworkDomain**. +**G.853.1:transportConnection** (attributes: **signalIdentification**, **directionality**) inherits from **G.853.10:plcmLinkConnection**. +**G.853.1:networkCTP** (attributes: **signalIdentification**, **pointDirectionality**) inherits from **G.853.10:plcmNetworkCTP**. +**prdRoutingConditions** (attribute: **prdArc-Point-orientedRouteComponents**) inherits from **prdRoute**. +**G.853.1:subnetwork** (attribute: **signalIdentification**) inherits from **prdSubnetwork**. +**prdRoute** (attributes: **prdIndividualRouteComponentsList**, **prdReturnedProperties**) is a standalone class. +**G.853.10:plcmLinkConnection** (attributes: **userLabel (imp)**, **plcmCallerId**) inherits from **prdLinkConnection**. +**G.853.10:plcmNetworkCTP** (attributes: **userLabel (imp)**, **plcmCallerId**) inherits from **prdNetworkCTP**. +**prdLinkConnection** and **prdNetworkCTP** are standalone classes. + +Inheritance diagram for Pre-provisioned Route Discovery (G.853.16). + +T0414290-00 + +Figure 1/G.853.16 – Pre-provisioned Route Discovery, inheritance diagram + +![UML class diagram for Pre-provisioned Route Discovery. The central class is prdLayerNetworkDomain, which has a 1..1 composition relationship with prdLink, prdNetworkTTP, prdTopologicalLinkEnd, prdRouteSet, and prdTopologicalLink. It also has a 1..1 composition relationship with prdAccessGroup, prdLinkConnection, prdNetworkCTP, prdLinkEnd, and prdSubnetwork. All these associations are labeled 'layerNetworkDomainIsMadeOf' and '+containerLND'. prdRouteSet has a 1..1 association with prdRoutingConditions (labeled '+routeSet' and 'prdRoutSetFulfillsRoutingConditions') and a 1..1 association with prdRoute (labeled '+routeSet' and 'prdRoutSetHasRoutes').](acfc53eca625d62b38aa2563efa95c3e_img.jpg) + +``` + +classDiagram + prdLayerNetworkDomain "1..1" *-- "1..*" prdAccessGroup : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdLink : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdLinkConnection : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdNetworkCTP : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdNetworkTTP : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdTopologicalLinkEnd : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdLinkEnd : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "1..*" prdRouteSet : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "0..*" prdSubnetwork : layerNetworkDomainIsMadeOf +containerLND + prdLayerNetworkDomain "1..1" *-- "0..*" prdTopologicalLink : layerNetworkDomainIsMadeOf +containerLND + prdRouteSet "1..1" -- "1..1" prdRoutingConditions : prdRoutSetFulfillsRoutingConditions +routeSet + prdRouteSet "1..1" -- "0..*" prdRoute : prdRoutSetHasRoutes +routeSet + prdRoutingConditions "1..1" -- "1..1" prdRoute : +fulfilledConditions +route + +``` + +UML class diagram for Pre-provisioned Route Discovery. The central class is prdLayerNetworkDomain, which has a 1..1 composition relationship with prdLink, prdNetworkTTP, prdTopologicalLinkEnd, prdRouteSet, and prdTopologicalLink. It also has a 1..1 composition relationship with prdAccessGroup, prdLinkConnection, prdNetworkCTP, prdLinkEnd, and prdSubnetwork. All these associations are labeled 'layerNetworkDomainIsMadeOf' and '+containerLND'. prdRouteSet has a 1..1 association with prdRoutingConditions (labeled '+routeSet' and 'prdRoutSetFulfillsRoutingConditions') and a 1..1 association with prdRoute (labeled '+routeSet' and 'prdRoutSetHasRoutes'). + +Figure 2/G.853.16 – Pre-provisioned Route Discovery, relationship diagram + +T0414300-00 + +# 8 Label references + +| Full label reference | Local label reference | +|------------------------------------------------------------------------|----------------------------| +| <"Rec. G.853.1", INFORMATION_OBJECT: accessGroup> | AccessGroup | +| <"Rec. G.853.1", INFORMATION_OBJECT: layerNetworkDomain> | LayerNetworkDomain | +| <"Rec. G.853.1", INFORMATION_OBJECT: link> | Link | +| <"Rec. G.853.1", INFORMATION_OBJECT: linkEnd> | LinkEnd | +| <"Rec. G.853.1", INFORMATION_OBJECT: networkInformationTop> | NetworkInformationTop | +| <"Rec. G.853.1", INFORMATION_OBJECT: networkTTP> | NetworkTTP | +| <"Rec. G.853.10", INFORMATION_OBJECT: plcMLinkConnection> | PlcMLinkConnection | +| <"Rec. G.853.10", INFORMATION_OBJECT: plcMNetworkCTP> | PlcMNetworkCTP | +| <"Rec. G.853.1", INFORMATION_OBJECT: subnetwork> | Subnetwork | +| <"Rec. G.853.1", INFORMATION_OBJECT: topologicalLink> | TopologicalLink | +| <"Rec. G.853.1", INFORMATION_OBJECT: topologicalLinkEnd> | TopologicalLinkEnd | +| | | +| | | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: layerNetworkDomainIsMadeOf> | LayerNetworkDomainIsMadeOf | +| | | +| | | +| | | +| | | + +# 9 Information object class definitions + +## 9.1 prdAccessGroup + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.2 prdLayerNetworkDomain + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.3 prdLink + + + +### DEFINITION + +"This object class is derived from . The relationship with the trails in the server layer is undefined." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.4 prdLinkConnection + + + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.5 prdLinkEnd + + + +### DEFINITION + +"This object class is derived from . The relationship with the networkTTPs in the server layer is undefined." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.6 prdNetworkCTP + + + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.7 prdNetworkTTP + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.8 prdRoute + + + +### DEFINITION + +"The prdRoute information object represents one of the routes in the prdRouteSet for an unprotected or a protected scheme. The prdRoutes information object is derived from ." + +### ATTRIBUTE + + + + + +### RELATIONSHIP + + + + + +## 9.9 prdRouteSet + + + +### DEFINITION + +"The prdRouteSet information object represents a set of routes for an unprotected or a protected scheme fulfilling a set of routing conditions. +The prdRouteSet information object is derived from ." + +### ATTRIBUTE + + + +### RELATIONSHIP + + + + + + + +## 9.10 prdRoutingConditions + + + + + +DEFINITION "This object class contains the request to return either arc-oriented or point-oriented route components and it reflects the optionally supplied conditions that has to be met by the returned routes. This class will be refined based on technology dependent characteristics (the enterprise viewpoint recommendation contains a list of examples). +The prdRoutingConditions information object is derived from ." + +### ATTRIBUTE + + + +### RELATIONSHIP + + + +## 9.11 prdSubnetwork + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.12 prdTopologicalLink + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +## 9.13 prdTopologicalLinkEnd + + + +### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +### RELATIONSHIP + + + +# 10 Information relationship definitions + +## 10.1 prdRouteSetFulfillsRoutingConditions + + + +### DEFINITION + +"The prdRouteSetFulfillsRoutingConditions relationship describes the association between the routeSet and the related conditions that are met by the contained routes." + +### ROLE + +#### routeSet + +"Played by an instance of the information object class." + +#### fulfilledConditions + +"Played by an instance of the object class." + +### INVARIANT + +##### inv\_1 + +"Only one object playing the routeSet role must be involved in the relationship." + +##### inv\_2 + +"Only one object playing the routingConditions role must be involved in the relationship." + +## 10.2 PrdRouteSetHasRoutes + + + +### DEFINITION + +"The prdRouteSetHasRoutes relationship describes the association between a routeSet and all its potential routes having the same routeEnds." + +### ROLE + +routeSet + +"Played by an instance of the information object class." + +route + +"Played by instances of the object class." + +### INVARIANT + +inv\_1 + +"One or more objects playing the role route may be involved in the relationship." + +inv\_2 + +"Only one object playing the role routeSet must be involved in the relationship." + +# 11 Static schemas + +-- none + +# 12 Dynamic schemas + +-- none + +# 13 Attributes + +## 13.1 prdArc-Point-orientedRouteComponents + + + +### DEFINITION + +"This attribute reflects the request to either return arc-oriented or point-oriented route components." + +## 13.2 prdReturnedProperties + + + +### DEFINITION + +"This attribute reflects the properties optionally associated with a returned route. It has to be refined based on technology dependent characteristics." + +## 13.3 prdRouteEnds + + + + + + + +### DEFINITION + +"This attribute contains the identifiers of the route ends of the prdRouteSet. The route ends may represent + +- linkConnection information objects, +- networkTTP information objects, +- networkCTP information objects, +- accessGroup information objects, +- link information objects, +- topologicalLink information objects, +- linkEnd information objects, +- topologicalLinkEnd information objects or +- subnetwork information objects." + +### prdIndividualRouteComponentsList + + + + + +### DEFINITION + +"This attribute contains all the individual route components of a route. They may belong to several individual routes when the caller have asked for a route which can be used in a protection scheme (the number of individual routes corresponds to the protection scheme requested)." + +# **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.853.3-199903-I_PDF-E/raw.md b/marked/G/T-REC-G.853.3-199903-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..1c5ff48c6b3be596dc3aa7fd4726a6cf28cd3a30 --- /dev/null +++ b/marked/G/T-REC-G.853.3-199903-I_PDF-E/raw.md @@ -0,0 +1,652 @@ + + +![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with the letters ITU and a lightning bolt. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.853.3** + +(03/99) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – +Management of transport network + +--- + +**Information viewpoint for topology management** + +ITU-T Recommendation G.853.3 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +*For further details, please refer to ITU-T List of Recommendations.* + +## **INFORMATION VIEWPOINT FOR TOPOLOGY MANAGEMENT** + +## **Summary** + +The topology management community is used to manage the topology of a layer network domain and the relationships between the resources of the layer network domain being managed. The service provided by the community allows for the creation and deletion of the following resources inside a layer network domain: subnetwork, link, topological link, link end, topological link end and access group. The service also provides a set of reporting actions to advise potential notification receivers of creation and deletion of resources in the community. The service is available between one single caller and one single provider. + +The partitioning of subnetworks and links is not addressed in this community. + +### **Source** + +ITU-T Recommendation G.853.3 was prepared by ITU-T Study Group 4 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 26th of March 1999. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +### NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +### INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +###### Page + +| | | | +|-----|---------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References ..... | 1 | +| 3 | Definitions ..... | 1 | +| 4 | Abbreviations ..... | 1 | +| 5 | Conventions ..... | 2 | +| 6 | Class diagrams ..... | 2 | +| 6.1 | UML class diagrams representing relationships between classes ..... | 2 | +| 6.2 | UML class diagram representing the inheritance hierarchy ..... | 6 | +| 7 | Label references ..... | 7 | +| 8 | Information object class definitions ..... | 8 | +| 8.1 | topmanAccessGroup ..... | 8 | +| 8.2 | topmanLayerNetworkDomain ..... | 8 | +| 8.3 | topmanLink ..... | 8 | +| 8.4 | topmanLinkEnd ..... | 8 | +| 8.5 | topmanNetworkTTP ..... | 9 | +| 8.6 | topmanSubnetwork ..... | 9 | +| 8.7 | topmanSubnetworkTP ..... | 9 | +| 8.8 | topmanTopologicalLink ..... | 9 | +| 8.9 | topmanTopologicalLinkEnd ..... | 10 | +| 9 | Information relationship definitions ..... | 10 | +| 10 | Static schemas ..... | 10 | +| 11 | Dynamic schemas ..... | 10 | +| 12 | Attributes ..... | 10 | + + + +## Recommendation G.853.3 + +## INFORMATION VIEWPOINT FOR TOPOLOGY MANAGEMENT + +(Geneva, 1999) + +# 1 Scope + +This information viewpoint specification is related to the topology management enterprise specification defined in Recommendation G.852.3. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.851.1 (1996), *Management of the transport network – Application of the RM-ODP framework.* +- [2] ITU-T Recommendation G.853. 1 (1999), *Common elements of the information viewpoint for the management of a transport network.* +- [3] ITU-T Recommendation G.852.3 (1999), *Enterprise viewpoint for topology management.* +- [4] ITU-T Recommendation G.854.3 (1999), *Computational viewpoint for topology management.* + +# 3 Definitions + +None. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|--------|-------------------------------------------------| +| AG | Access Group | +| CTP | Connection Termination Point | +| Id | Identifier | +| imp | imported | +| LE | Link End | +| LND | Layer Network Domain | +| RM-ODP | Reference Model for Open Distributed Processing | +| SN | Subnetwork | +| SNC | Subnetwork Connection | + +| | | +|--------|------------------------------| +| SNTP | Subnetwork Termination Point | +| TL | Topological Link | +| TLE | Topological Link End | +| topman | topology management | +| TP | Termination Point | +| TTP | Trail Termination Point | +| UML | Unified Modelling Language | + +# 5 Conventions + +None. + +# 6 Class diagrams + +## 6.1 UML class diagrams representing relationships between classes + +See Figures 1 to 4. + +![UML class diagram showing relationships between topmanLayerNetworkDomain, topmanAccessGroup, and topmanNetworkTTP classes.](5860ad6bd2a2dd8d1ab12864b8f90f37_img.jpg) + +``` + +classDiagram + class topmanLayerNetworkDomain + class topmanAccessGroup + class topmanNetworkTTP + + topmanLayerNetworkDomain "1..1" containerLND -- "(1..N) element" topmanAccessGroup : IsMadeOf + topmanAccessGroup "1..1" containerAG -- "(1..N) elementTTP" topmanNetworkTTP : MadeOfNetworkTTPs + +``` + +The diagram illustrates three classes and their relationships: + +- topmanLayerNetworkDomain**: The top class in the hierarchy. +- topmanAccessGroup**: The middle class, related to topmanLayerNetworkDomain. +- topmanNetworkTTP**: The bottom class, related to topmanAccessGroup. + +Relationships: + +- A vertical association between **topmanLayerNetworkDomain** and **topmanAccessGroup**. The role **containerLND** is associated with the multiplicity **(1..1)** at the topmanLayerNetworkDomain end. The role **element** is associated with the multiplicity **(1..N)** at the topmanAccessGroup end. The relationship is labeled *layerNetworkDomain IsMadeOf*. +- A vertical association between **topmanAccessGroup** and **topmanNetworkTTP**. The role **containerAG** is associated with the multiplicity **(1..1)** at the topmanAccessGroup end. The role **elementTTP** is associated with the multiplicity **(1..N)** at the topmanNetworkTTP end. The relationship is labeled *accessGroupIs MadeOfNetworkTTPs*. + +UML class diagram showing relationships between topmanLayerNetworkDomain, topmanAccessGroup, and topmanNetworkTTP classes. + +T0410690-99 + +Figure 1/G.853.3 – UML class diagram representing topmanAccessGroup relationships + +![UML class diagram for topmanLayerNetworkDomain showing relationships between topmanLink, topmanLinkEnd, linkExtremity, G.853.1: linkConnection, topmanSubnetwork, and G.853.1: networkCTP.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg) + +``` + +classDiagram + class topmanLayerNetworkDomain + class topmanLink + class topmanLinkEnd + class linkExtremity + class G853_1_linkConnection["G.853.1: linkConnection"] + class topmanSubnetwork + class G853_1_networkCTP["G.853.1: networkCTP"] + class topmanAccessGroup + class topmanSubnetwork_sub + + topmanLayerNetworkDomain "1..1" containerLND -- "(1..N) element" topmanLink : layerNetworkDomain IsMadeOf + topmanLayerNetworkDomain "1..1" containerLND -- "(1..N) element" topmanLinkEnd : layerNetworkDomain IsMadeOf + topmanLink "(1..1)" transferCapacityLink -- "(1..1) a_endTopological and z_endTopological" linkExtremity : linkBinds + topmanLink "(1..1)" containerLink -- "(1..N) elementLC" G853_1_linkConnection : linkHas LinkConnections + topmanLinkEnd "(1..1)" transferCapacityLE -- "(1..1) topologicalEntity" topmanSubnetwork : linkEndIsBoundTo + topmanLinkEnd "(1..1)" containerLE -- "(1..N) elementCTP" G853_1_networkCTP : linkEndHas NetworkCTPs + topmanAccessGroup --> linkExtremity + topmanSubnetwork_sub --> linkExtremity + +``` + +The diagram illustrates the relationships within the **topmanLayerNetworkDomain**. At the top, **topmanLink** and **topmanLinkEnd** are elements of a **layerNetworkDomain** (containerLND). **topmanLink** binds to **linkExtremity** (transferCapacityLink) and has **linkConnections** (G.853.1: linkConnection). **topmanLinkEnd** is bound to **topmanSubnetwork** (transferCapacityLE) and has **networkCTPs** (G.853.1: networkCTP). **linkExtremity** is associated with **topmanAccessGroup** and **topmanSubnetwork**. A small note 'T0410700-99' is present in the bottom right. + +UML class diagram for topmanLayerNetworkDomain showing relationships between topmanLink, topmanLinkEnd, linkExtremity, G.853.1: linkConnection, topmanSubnetwork, and G.853.1: networkCTP. + +**Figure 2/G.853.3 – UML class diagram representing topmanLink and topmanLinkEnd relationships** + +![UML class diagram representing topmanTopologicalLink and topmanTopologicalLinkEnd relationships. The diagram shows topmanLayerNetworkDomain at the top, which is composed of topmanTopologicalLink and topmanTopologicalLinkEnd elements. topmanTopologicalLink is associated with linkExtremity (transfer CapacityLink), G.853.1: trail (clientTL, serverTrail), and topmanSubnetwork (topologicalEntity). topmanTopologicalLinkEnd is associated with linkExtremity (transfer CapacityLE), G.853.1: networkTTP (clientTLE, serverTTP), and topmanSubnetwork (topologicalEntity). linkExtremity is further associated with topmanAccessGroup and topmanSubnetwork.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +``` + +classDiagram + class topmanLayerNetworkDomain + class topmanTopologicalLink + class topmanTopologicalLinkEnd + class linkExtremity + class G853_1trail["G.853.1: trail"] + class topmanSubnetwork + class G853_1networkTTP["G.853.1: networkTTP"] + class topmanAccessGroup + + topmanLayerNetworkDomain "1..1" containerLND -- "1..N" element : layerNetworkDomain IsMadeOf + topmanTopologicalLink -- topmanLayerNetworkDomain + topmanTopologicalLinkEnd -- topmanLayerNetworkDomain + topmanTopologicalLink "1..1" transfer CapacityLink -- "1..1" and "1..1" a_endTopological and z_endTopological : linkBinds -- linkExtremity + topmanTopologicalLink "1..N" clientTL -- "1..1" G853_1trail : topologicalLinkIsSupportedByTrail + topmanTopologicalLink "1..1" serverTrail -- "1..1" topologicalEntity : -- topmanSubnetwork + topmanTopologicalLinkEnd "1..1" transfer CapacityLE -- "1..1" and "1..1" a_endTopological and z_endTopological : linkEndIsBoundTo -- linkExtremity + topmanTopologicalLinkEnd "1..N" clientTLE -- "1..1" G853_1networkTTP : topologicalLinkEndIsSupportedByNetworkTTP + topmanTopologicalLinkEnd "1..1" serverTTP -- "1..1" topologicalEntity : -- topmanSubnetwork + linkExtremity -- topmanAccessGroup + linkExtremity -- topmanSubnetwork + +``` + +UML class diagram representing topmanTopologicalLink and topmanTopologicalLinkEnd relationships. The diagram shows topmanLayerNetworkDomain at the top, which is composed of topmanTopologicalLink and topmanTopologicalLinkEnd elements. topmanTopologicalLink is associated with linkExtremity (transfer CapacityLink), G.853.1: trail (clientTL, serverTrail), and topmanSubnetwork (topologicalEntity). topmanTopologicalLinkEnd is associated with linkExtremity (transfer CapacityLE), G.853.1: networkTTP (clientTLE, serverTTP), and topmanSubnetwork (topologicalEntity). linkExtremity is further associated with topmanAccessGroup and topmanSubnetwork. + +T0410710-99 + +Figure 3/G.853.3 – UML class diagram representing topmanTopologicalLink and topmanTopologicalLinkEnd relationships + +![UML class diagram representing topmanSubnetwork relationships. The diagram shows topmanLayerNetworkDomain at the top, connected to topmanSubnetwork via containerLND (1..1) and element (1..N) relationships. topmanSubnetwork is connected to topmanLink, topmanLinkEnd, G.853.1: linkConnection, topmanSubnetworkTP, and G.853.1: subnetworkConnection. These are further connected to topmanNetworkTP via abstractionSNTP and subnetworkTPIs relationships.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +``` + +classDiagram + class topmanLayerNetworkDomain + class topmanSubnetwork + class topmanLink + class topmanLinkEnd + class G853_1_linkConnection["G.853.1: linkConnection"] + class topmanSubnetworkTP + class G853_1_subnetworkConnection["G.853.1: subnetworkConnection"] + class topmanNetworkTP + + topmanLayerNetworkDomain "1..1" containerLND --> "1..N" element : topmanSubnetwork + topmanSubnetwork "1..1" transfer CapacityLE --> "1..1" topological Entity : topmanLink + topmanSubnetwork "1..1" transfer CapacityLE --> "1..1" topological Entity : topmanLinkEnd + topmanSubnetwork "1..1" transfer CapacityLink --> "1..1" topologicalEntity : G.853.1: linkConnection + topmanSubnetwork "1..1" containerSN --> "1..1" topmanSubnetworkTP + topmanSubnetwork "1..1" linkEndsBoundTo --> "1..N" elementSNC : G.853.1: subnetworkConnection + G.853.1: linkConnection "1..1" a_endTopological --> "1..1" z_endTopological : topmanSubnetworkTP + G.853.1: subnetworkConnection "1..N" --> "1..N" abstractionSNTP : topmanSubnetworkTP + topmanSubnetworkTP "1..N" subnetworkTPIs --> "1..1" extremity : topmanNetworkTP + +``` + +T0410720-99 + +UML class diagram representing topmanSubnetwork relationships. The diagram shows topmanLayerNetworkDomain at the top, connected to topmanSubnetwork via containerLND (1..1) and element (1..N) relationships. topmanSubnetwork is connected to topmanLink, topmanLinkEnd, G.853.1: linkConnection, topmanSubnetworkTP, and G.853.1: subnetworkConnection. These are further connected to topmanNetworkTP via abstractionSNTP and subnetworkTPIs relationships. + +Figure 4/G.853.3 – UML class diagram representing topmanSubnetwork relationships + +## 6.2 UML class diagram representing the inheritance hierarchy + +See Figure 5. + +![UML class diagram representing the inheritance hierarchy for G.853.3. The diagram shows a hierarchy of classes starting from G.853.1: networkInformationTop at the root. Below it are G.853.1: link, G.853.1: topologicalLink, G.853.1: linkEnd, and G.853.1: topologicalLinkEnd. Further down are topmanLink, topmanTopologicalLink, topmanLinkEnd, and topmanTopologicalLinkEnd. To the right are G.853.1: accessGroup, G.853.1: subnetworkTP, and G.853.1: networkTTP, with topmanAccessGroup, topmanSubnetworkTP, and topmanNetworkTTP below them. At the bottom are G.853.1: layerNetworkDomain and G.853.1: subnetwork, with topmanLayerNetworkDomain and topmanSubnetwork below them. All classes inherit from G.853.1: networkInformationTop.](042733dc5e8e7f5f30b60adba3266cde_img.jpg) + +``` + +classDiagram + class G853_1_networkInformationTop["G.853.1: networkInformationTop"] { + resourceId + } + class G853_1_link["G.853.1: link"] { + signalIdentification + linkDirectionality + } + class G853_1_topologicalLink["G.853.1: topologicalLink"] { + signalIdentification + linkDirectionality + } + class G853_1_linkEnd["G.853.1: linkEnd"] { + signalIdentification + topologicalEndDirection + } + class G853_1_topologicalLinkEnd["G.853.1: topologicalLinkEnd"] { + signalIdentification + topologicalEndDirection + } + class topmanLink["topmanLink"] { + G.853.1: userLabel (imp) + } + class topmanTopologicalLink["topmanTopologicalLink"] { + G.853.1: userLabel (imp) + } + class topmanLinkEnd["topmanLinkEnd"] { + G.853.1: userLabel (imp) + } + class topmanTopologicalLinkEnd["topmanTopologicalLinkEnd"] { + G.853.1: userLabel (imp) + } + class G853_1_accessGroup["G.853.1: accessGroup"] { + signalIdentification + topologicalEndDirection + } + class G853_1_subnetworkTP["G.853.1: subnetworkTP"] { + signalIdentification + pointDirectionality + } + class G853_1_networkTTP["G.853.1: networkTTP"] { + signalIdentification + pointDirectionality + } + class topmanAccessGroup["topmanAccessGroup"] { + G.853.1: userLabel (imp) + } + class topmanSubnetworkTP["topmanSubnetworkTP"] { + } + class topmanNetworkTTP["topmanNetworkTTP"] { + } + class G853_1_layerNetworkDomain["G.853.1: layerNetworkDomain"] { + signalIdentification + } + class G853_1_subnetwork["G.853.1: subnetwork"] { + signalIdentification + } + class topmanLayerNetworkDomain["topmanLayerNetworkDomain"] { + } + class topmanSubnetwork["topmanSubnetwork"] { + G.853.1: userLabel (imp) + } + + G853_1_link --|> G853_1_networkInformationTop + G853_1_topologicalLink --|> G853_1_networkInformationTop + G853_1_linkEnd --|> G853_1_networkInformationTop + G853_1_topologicalLinkEnd --|> G853_1_networkInformationTop + topmanLink --|> G853_1_link + topmanTopologicalLink --|> G853_1_topologicalLink + topmanLinkEnd --|> G853_1_linkEnd + topmanTopologicalLinkEnd --|> G853_1_topologicalLinkEnd + G853_1_accessGroup --|> G853_1_networkInformationTop + G853_1_subnetworkTP --|> G853_1_networkInformationTop + G853_1_networkTTP --|> G853_1_networkInformationTop + topmanAccessGroup --|> G853_1_accessGroup + topmanSubnetworkTP --|> G853_1_subnetworkTP + topmanNetworkTTP --|> G853_1_networkTTP + G853_1_layerNetworkDomain --|> G853_1_networkInformationTop + G853_1_subnetwork --|> G853_1_networkInformationTop + topmanLayerNetworkDomain --|> G853_1_layerNetworkDomain + topmanSubnetwork --|> G853_1_subnetwork + +``` + +UML class diagram representing the inheritance hierarchy for G.853.3. The diagram shows a hierarchy of classes starting from G.853.1: networkInformationTop at the root. Below it are G.853.1: link, G.853.1: topologicalLink, G.853.1: linkEnd, and G.853.1: topologicalLinkEnd. Further down are topmanLink, topmanTopologicalLink, topmanLinkEnd, and topmanTopologicalLinkEnd. To the right are G.853.1: accessGroup, G.853.1: subnetworkTP, and G.853.1: networkTTP, with topmanAccessGroup, topmanSubnetworkTP, and topmanNetworkTTP below them. At the bottom are G.853.1: layerNetworkDomain and G.853.1: subnetwork, with topmanLayerNetworkDomain and topmanSubnetwork below them. All classes inherit from G.853.1: networkInformationTop. + +T0410730-99 + +Figure 5/G.853.3 – UML class diagram representing the inheritance hierarchy + +# 7 Label references + +See Table 1. + +**Table 1/G.853.3 – Label references** + +| Full label reference | Local label reference | +|----------------------------------------------------------------------------------------------------|-----------------------------------------------------| +| <"Rec. G.853.1", INFORMATION_OBJECT:accessGroup> | accessGroup | +| <"Rec. G.853.1", INFORMATION_OBJECT:layerNetworkDomain> | layerNetworkDomain | +| <"Rec. G.853.1", INFORMATION_OBJECT:link> | link | +| <"Rec. G.853.1", INFORMATION_OBJECT:linkEnd> | linkEnd | +| <"Rec. G.853.1", INFORMATION_OBJECT:networkTTP> | networkTTP | +| <"Rec. G.853.1", INFORMATION_OBJECT:subnetwork> | subnetwork | +| <"Rec. G.853.1", INFORMATION_OBJECT:subnetworkTP> | subnetworkTP | +| <"Rec. G.853.1", INFORMATION_OBJECT: topologicalLink> | topologicalLink | +| <"Rec. G.853.1", INFORMATION_OBJECT: topologicalLinkEnd> | topologicalLinkEnd | +| <"Rec. G.853.1", ATTRIBUTE:userLabel> | userLabel | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
accessGroupIsMadeOfNetworkTTPs> | accessGroupIsMadeOfNetworkTTPs | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
layerNetworkDomainIsMadeOf> | layerNetworkDomainIsMadeOf | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:linkBinds> | linkBinds | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
linkConnectionIsTerminatedByTopological
Entities> | linkConnectionIsTerminatedByTopological
Entities | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
linkEndHasNetworkCTPs> | linkEndHasNetworkCTPs | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:linkEndIsBoundTo> | linkEndIsBoundTo | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
linkHasLinkConnections> | linkHasLinkConnections | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
subnetworkHasSubnetworkConnections> | subnetworkHasSubnetworkConnections | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
subnetworkIsDelimitedBy> | subnetworkIsDelimitedBy | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
subnetworkTPIsRelatedToExtremity> | subnetworkTPIsRelatedToExtremity | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
topologicalLinkEndIsSupportedByNetworkTTP> | topologicalLinkEndIsSupportedByNetworkTTP | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
topologicalLinkIsSupportedByTrail> | topologicalLinkIsSupportedByTrail | + +# 8 Information object class definitions + +## 8.1 topmanAccessGroup + +This information concept is related to the following enterprise entities: + + +DEFINITION +"This object class is derived from ." +ATTRIBUTE + +RELATIONSHIP + + + + +## 8.2 topmanLayerNetworkDomain + +This information concept is related to the following enterprise entities: + + +DEFINITION +"This object class is derived from ." +ATTRIBUTE +-- none additional +RELATIONSHIP + + +## 8.3 topmanLink + +This information concept is related to the following enterprise entities: + + +DEFINITION +"This object class is derived from ." +ATTRIBUTE + +RELATIONSHIP + + + + +## 8.4 topmanLinkEnd + +This information concept is related to the following enterprise entities: + + +DEFINITION +"This object class represents the extremity of a link and a capacity at the boundary of a subnetwork. It also may represent a grouping of networkCTPs. The object class is derived from ." +ATTRIBUTE + +RELATIONSHIP + + + + +## 8.5 **topmanNetworkTTP** + +This information concept is related to the following enterprise entities: + + + +#### DEFINITION + +"This object class is derived from <*networkTTP*>." + +#### ATTRIBUTE + +-- none additional + +#### RELATIONSHIP + + + + + +## 8.6 **topmanSubnetwork** + +This information concept is related to the following enterprise entities: + + + +#### DEFINITION + +"This object class is derived from <*subnetwork*>." + +#### ATTRIBUTE + + + +#### RELATIONSHIP + + + + + + + + +## 8.7 **topmanSubnetworkTP** + +This information concept is related to the following enterprise entities: + + + +#### DEFINITION + +"This object class is derived from <*subnetworkTP*>." + +#### ATTRIBUTE + +-- none additional + +#### RELATIONSHIP + + + + + +## 8.8 **topmanTopologicalLink** + +This information concept is related to the following enterprise entities: + + + +#### DEFINITION + +"This object class is derived from <*topologicalLink*>." + +#### ATTRIBUTE + + + +#### RELATIONSHIP + + + + + +## **8.9 topmanTopologicalLinkEnd** + +This information concept is related to the following enterprise entities: + + + +#### **DEFINITION** + +"This object class represents the extremity of a topological link and a capacity at the boundary of a subnetwork. It also may represent a grouping of networkCTPs. The object class is derived from ." + +#### **ATTRIBUTE** + + + +#### **RELATIONSHIP** + + + + + + + +## **9 Information relationship definitions** + +None additional. + +## **10 Static schemas** + +None. + +## **11 Dynamic schemas** + +None. + +## **12 Attributes** + +None additional. + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.870-201611-I_PDF-E/raw.md b/marked/G/T-REC-G.870-201611-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..1d91779582998d00bdf1e358de23bd14d5302fca --- /dev/null +++ b/marked/G/T-REC-G.870-201611-I_PDF-E/raw.md @@ -0,0 +1,472 @@ + + +**ITU-T** + +**G.870/Y.1352** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(11/2016) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital networks – Optical transport networks + +SERIES Y: GLOBAL INFORMATION +INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, +NEXT-GENERATION NETWORKS, INTERNET OF +THINGS AND SMART CITIES + +Internet protocol aspects – Transport + +# --- **Terms and definitions for optical transport networks** + +Recommendation ITU-T G.870/Y.1352 + +## ITU-T G-SERIES RECOMMENDATIONS + +## TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Synchronization, quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +For further details, please refer to the list of ITU-T Recommendations. + +### Recommendation ITU-T G.870/Y.1352 + +# Terms and definitions for optical transport networks + +## Summary + +Recommendation ITU-T G.870/Y.1352 provides terms, definitions and abbreviations used in optical transport network (OTN) Recommendations. In this edition, Recommendations (namely Source Recommendation per term) are identified that originally introduced OTN terms and are primarily responsible for the definitions of those terms. For the OTN terms defined in the previous edition, this edition provides the pointers to the Sources Recommendations as a directory. Official definitions are now given in those Source Recommendations. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.870/Y.1352 | 2004-06-13 | 15 | 11.1002/1000/7337 | +| 1.1 | ITU-T G.870/Y.1352 (2004) Amd. 1 | 2005-06-29 | 15 | 11.1002/1000/7338 | +| 2.0 | ITU-T G.870/Y.1352 | 2008-03-29 | 15 | 11.1002/1000/9375 | +| 2.1 | ITU-T G.870/Y.1352 (2008) Amd.1 | 2009-11-13 | 15 | 11.1002/1000/10402 | +| 3.0 | ITU-T G.870/Y.1352 | 2010-07-29 | 15 | 11.1002/1000/10879 | +| 4.0 | ITU-T G.870/Y.1352 | 2012-02-13 | 15 | 11.1002/1000/11492 | +| 5.0 | ITU-T G.870/Y.1352 | 2012-10-29 | 15 | 11.1002/1000/11789 | +| 5.1 | ITU-T G.870/Y.1352 (2012) Cor. 1 | 2013-08-29 | 15 | 11.1002/1000/11985 | +| 6.0 | ITU-T G.870/Y.1352 | 2016-11-13 | 15 | 11.1002/1000/13085 | + +## Keywords + +Directory, optical transport network, OTN, source recommendation, terminology, terms. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2017 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|----------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms previously defined in this Recommendation..... | 4 | + + + +## Terms and definitions for optical transport networks + +## 1 Scope + +This Recommendation contains a listing of the terms that are broadly used in the Recommendations associated with optical transport networks (OTNs). In the previous editions, [ITU-T G.870] collected and defined major OTN terms. In this edition, the Recommendations that originally introduced and primarily describe those OTN terms are identified as the Source Recommendation. From this revision, the Source Recommendations are primarily responsible for the definitions of those terms. Official definitions are now provided by those Source Recommendations. + +For those OTN terms defined in the previous edition, this edition of [ITU-T G.870] provides the pointers to the Source Recommendations as a directory. + +Some terms that were defined in the previous editions are now widely used in a general sense and there is no identified need to define them. Some terms are obsolete and are not recommended to be used. + +Abbreviations and acronyms, which the previous editions listed, are not included in this edition. + +It should be noted that the terms contained in this edition are based on the previous edition and are not exhaustive in OTN terminology. + +Directory document and/or service that indicate(s) the source Recommendations per OTN term are under study. + +OTN terms specific to synchronization or physical layer characteristics are not a part of this Recommendation. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.694.1] Recommendation ITU-T G.694.1 (2012), *Spectral grids for WDM applications: DWDM frequency grid*. +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016), *Interfaces for the optical transport network*. +- [ITU-T G.780] Recommendation ITU-T G.780/Y.1351 (2010), *Terms and definitions for synchronous digital hierarchy (SDH) networks*. +- [ITU-T G.798] Recommendation ITU-T G.798 (2012), *Characteristics of optical transport network hierarchy equipment functional blocks*. +- [ITU-T G.800] Recommendation ITU-T G.800 (2016), *Unified functional architecture of transport networks*. +- [ITU-T G.801.1] Recommendation ITU-T G.801.1/Y.1307 (2016), *Ethernet service characteristics*. + +- [ITU-T G.805] Recommendation ITU-T G.805 (2000), *Generic functional architecture of transport networks.* +- [ITU-T G.806] Recommendation ITU-T G.806 (2009), *Characteristics of transport equipment – Description methodology and generic functionality.* +- [ITU-T G.808] Recommendation ITU-T G.808 (2016), *Terms and definitions for network protection and restoration.* +- [ITU-T G.872] Recommendation ITU-T G.872 (2016), *Architecture of optical transport networks.* +- [ITU-T G.874] Recommendation ITU-T G.874 (2013), *Management aspects of optical transport network elements.* +- [ITU-T G.7044] Recommendation ITU-T G.7044/Y.1347 (2011), *Hitless adjustment of ODUflex(GFP).* +- [ITU-T G.7710] Recommendation ITU-T G.7710/Y.1701 (2007), *Common equipment management function requirements.* +- [ITU-T G.7712] Recommendation ITU-T G.7712/Y.1703 (2008), *Architecture and specification of data communication network.* +- [ITU-T G.8201] Recommendation ITU-T G.8201 (2011), *Error performance parameters and objectives for multi-operator international paths within the optical transport network.* +- [ITU-T M.3010] Recommendation ITU-T M.3010 (2000), *Principles for a telecommunications management network.* +- [ITU-T M.3013] Recommendation ITU-T M.3013 (2000), *Considerations for a telecommunications management network.* +- [ITU-T X.700] Recommendation ITU-T X.700 (1992), *Management framework for Open Systems Interconnection (OSI) for CCITT applications.* + +## 3 Definitions + +### 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **adaptation:** [ITU-T G.805]. +- 3.1.2 **adaptation function:** [ITU-T G.806]. +- 3.1.3 **adapted information:** [ITU-T G.805]. +- 3.1.4 **administrative domain:** [ITU-T G.805]. +- 3.1.5 **atomic function:** [ITU-T G.806]. +- 3.1.6 **automatic protection switching (APS):** [ITU-T G.780]. +- 3.1.7 **block:** [ITU-T G.780]. +- 3.1.8 **characteristic information (CI):** [ITU-T G.805]. +- 3.1.9 **connection:** [ITU-T G.805]. +- 3.1.10 **connection function (C):** [ITU-T G.806]. +- 3.1.11 **connection point (CP):** [ITU-T G.806]. +- 3.1.12 **connection supervision:** [ITU-T G.805]. + +- 3.1.13 **data communications channel (DCC)**: [ITU-T G.780]. +- 3.1.14 **defect**: [ITU-T G.806]. +- 3.1.15 **errored block (EB)**: [ITU-T G.780]. +- 3.1.16 **embedded communication channel (ECC)**: [ITU-T G.7712]. +- 3.1.17 **failure**: [ITU-T G.806]. +- 3.1.18 **fault**: [ITU-T G.806]. +- 3.1.19 **function**: [ITU-T G.806]. +- 3.1.20 **layer**: [ITU-T G.780]. +- 3.1.21 **link connection**: [ITU-T G.805]. +- 3.1.22 **managed object**: [ITU-T X.700]. +- 3.1.23 **management application function (MAF)**: [ITU-T G.780]. +- 3.1.24 **management information (MI)**: [ITU-T G.806]. +- 3.1.25 **member**: [ITU-T G.806]. +- 3.1.26 **message communication function**: [ITU-T M.3013]. +- 3.1.27 **multiplex section (MS)**: [ITU-T G.780]. +- 3.1.28 **multiplex section overhead (MSOH)**: [ITU-T G.780]. +- 3.1.29 **network**: [ITU-T G.805]. +- 3.1.30 **network connection (NC)**: [ITU-T G.805]. +- 3.1.31 **network element**: [ITU-T M.3010]. +- 3.1.32 **network element function (NEF)**: [ITU-T M.3010]. +- 3.1.33 **network node interface (NNI)**: [ITU-T G.780]. +- 3.1.34 **operations systems function (OSF)**: [ITU-T M.3010]. +- 3.1.35 **path**: [ITU-T G.806]. +- 3.1.36 **path overhead (POH)**: [ITU-T G.780]. +- 3.1.37 **process**: [ITU-T G.806]. +- 3.1.38 **reference point**: [ITU-T G.780]. +- 3.1.39 **section**: [ITU-T G.806]. +- 3.1.40 **signal degrade (SD)**: [ITU-T G.806]. +- 3.1.41 **signal fail (SF)**: [ITU-T G.806]. +- 3.1.42 **subnetwork**: [ITU-T G.805]. +- 3.1.43 **subnetwork connection (SNC)**: [ITU-T G.805]. +- 3.1.44 **synchronous transport module (STM)**: [ITU-T G.780]. +- 3.1.45 **telecommunications management network**: [ITU-T M.3010]. +- 3.1.46 **trail**: [ITU-T G.805]. +- 3.1.47 **trail termination function (TT)**: [ITU-T G.806]. + +### 3.2 Terms previously defined in this Recommendation + +The previous editions of this Recommendation defined the following terms. The latest definitions are now given in the Recommendations associated with the terms as below. Some terms are now widely used in a general sense and there is no identified need to define them. Some terms are obsolete and are not recommended to be used. + +- 3.2.1 **1+1 (protection) architecture:** [ITU-T G.808]. +- 3.2.2 **1:n (protection) architecture ( $n \geq 1$ ):** [ITU-T G.808]. +- 3.2.3 **(1:1)n protection architecture:** [ITU-T G.808]. +- 3.2.4 **access function (AC):** [ITU-T G.798]. +- 3.2.5 **active transport entity:** [ITU-T G.808]. +- 3.2.6 **adaptation management:** Widely used in a general sense. +- 3.2.7 **APS-byte pass-through:** [ITU-T G.808]. +- 3.2.8 **APS channel:** [ITU-T G.808]. +- 3.2.9 **APS protocol: 1-phase:** [ITU-T G.808]. +- 3.2.10 **APS protocol: 2-phase:** [ITU-T G.808]. +- 3.2.11 **APS protocol: 3-phase:** [ITU-T G.808]. +- 3.2.12 **bridge:** [ITU-T G.808]. + - 3.2.12.1 **permanent bridge:** [ITU-T G.808]. + - 3.2.12.2 **broadcast bridge:** [ITU-T G.808]. + - 3.2.12.3 **selector bridge:** [ITU-T G.808]. +- 3.2.13 **CBRx:** [ITU-T G.798]. +- 3.2.14 **CBR2G5:** Refer to the description in [ITU-T G.798]. +- 3.2.15 **CBR10G:** Refer to the description in [ITU-T G.709]. +- 3.2.16 **CBR40G:** Refer to the description in [ITU-T G.709]. +- 3.2.17 **central frequency:** Refer to the description in [ITU-T G.694.1]. +- 3.2.18 **clear (CLR):** [ITU-T G.808]. +- 3.2.19 **clear lockout of normal traffic signal #i:** [ITU-T G.808]. +- 3.2.20 **connection monitoring end-point (CMEP):** [ITU-T G.709]. +- 3.2.21 **connectivity supervision:** Widely used in a general sense. +- 3.2.22 **continuity supervision:** Widely used in a general sense. +- 3.2.23 **crossing APS-bytes:** [ITU-T G.808]. +- 3.2.24 **detection time:** [ITU-T G.808]. +- 3.2.25 **do not revert normal traffic signal #i (DNR #i):** [ITU-T G.808]. +- 3.2.26 **effective frequency slot:** [ITU-T G.872]. +- 3.2.27 **end-to-end overhead/OAM (e):** Widely used in a general sense. +- 3.2.28 **entity:** Widely used in a general sense. +- 3.2.29 **escalation:** Widely used in a general sense. +- 3.2.30 **exercise signal #i (EX):** [ITU-T G.808]. + +- 3.2.31 **extra traffic signal:** [ITU-T G.808]. +- 3.2.32 **forced switch for extra traffic signal (FS #ExtraTrafficSignalNumber):** [ITU-T G.801.1]. +- 3.2.33 **forced switch for normal traffic signal #i (FS #i):** [ITU-T G.801.1]. +- 3.2.34 **forced switch for null signal (FS #0):** [ITU-T G.801.1]. +- 3.2.35 **freeze:** [ITU-T G.808]. +- 3.2.36 **full pass-through:** [ITU-T G.808]. +- 3.2.37 **group:** [ITU-T G.808]. +- 3.2.38 **GMP normal mode:** Refer to the description in [ITU-T G.7044]. +- 3.2.39 **GMP special mode:** Refer to the description in [ITU-T G.7044]. +- 3.2.40 **head-end:** [ITU-T G.808]. +- 3.2.41 **hitless activation/deactivation of a connection monitor:** Widely used in a general sense. +- 3.2.42 **hitless protection switch:** [ITU-T G.808]. +- 3.2.43 **hold-off time:** [ITU-T G.808]. +- 3.2.44 **hypothetical reference optical path:** [ITU-T G.8201]. +- 3.2.45 **impairment:** [ITU-T G.808]. +- 3.2.46 **intermediate node:** [ITU-T G.808]. +- 3.2.47 **intra-domain interface (IaDI):** Widely used in a general sense. +- 3.2.48 **inter-domain interface (IrDI):** Widely used in a general sense. +- 3.2.49 **link capacity adjustment scheme (LCAS):** Obsolete. +- 3.2.50 **local craft terminal:** [ITU-T G.7710]. +- 3.2.51 **lockout of normal traffic signal #i:** [ITU-T G.808]. +- 3.2.52 **lockout of protection transport entity #i (LO #i):** [ITU-T G.808]. +- 3.2.53 **maintenance indication:** Obsolete. +- 3.2.54 **management communications:** Widely used in a general sense. +- 3.2.55 **manual switch for extra traffic signal (MS #ExtraTrafficSignalNumber):** [ITU-T G.801.1]. +- 3.2.56 **manual switch for normal traffic signal #i (MS #i):** [ITU-T G.801.1]. +- 3.2.57 **manual switch for null signal (MS #0):** [ITU-T G.801.1]. +- 3.2.58 **media element:** Refer to the description in [ITU-T G.872]. +- 3.2.59 **m:n (protection) architecture:** [ITU-T G.808]. +- 3.2.60 **network media channel:** [ITU-T G.872]. +- 3.2.61 **network survivability:** [ITU-T G.808]. +- 3.2.62 **no request (NR):** [ITU-T G.808]. +- 3.2.63 **non-associated overhead (naOH):** [ITU-T G.709]. +- 3.2.64 **non-revertive (protection) operation:** [ITU-T G.808]. +- 3.2.65 **normal traffic signal:** [ITU-T G.808]. +- 3.2.66 **null signal:** [ITU-T G.808]. +- 3.2.67 **optical carrier group of order n (OCG-n[r]):** Obsolete. + +- 3.2.67.1 **OCG with full functionality (OCG-n)**: Obsolete. +- 3.2.67.2 **OCG with reduced functionality (OCG-nr)**: Obsolete. +- 3.2.68 **optical channel (OCh[r])**: Refer to OCh in [ITU-T G.709]. +- 3.2.68.1 **optical channel with full functionality (OCh)**: Refer to OCh in [ITU-T G.709]. +- 3.2.68.2 **optical channel with reduced functionality (OChr)**: Refer to OCh in [ITU-T G.709]. +- 3.2.69 **optical channel carrier (OCC[r])**: Obsolete. +- 3.2.69.1 **OCC with full functionality (OCC)**: Obsolete. +- 3.2.69.2 **OCC with reduced functionality (OCCr)**: Obsolete. +- 3.2.70 **optical channel data unit (ODUk)**: Refer to ODU in [ITU-T G.709]. +- 3.2.71 **optical channel data unit-k path (ODUk path) (ODUkP)**: Refer to ODU in [ITU-T G.709]. +- 3.2.72 **optical channel data unit-k, tandem connection sublayer (ODUk TCM) (ODUkT)**: Refer to ODU in [ITU-T G.709]. +- 3.2.73 **optical channel payload unit (OPUk)**: Refer to OPU in [ITU-T G.709]. +- 3.2.73.1 **OPUk multiframe**: Refer to OPU in [ITU-T G.709]. +- 3.2.74 **optical channel transport unit (OTUk[V])**: Refer to OTU in [ITU-T G.709]. +- 3.2.74.1 **completely standardized OTUk (OTUk)**: Refer to OTU in [ITU-T G.709]. +- 3.2.74.2 **functionally standardized OTUk (OTUkV)**: Refer to OTU in [ITU-T G.709]. +- 3.2.75 **optical multiplex unit (OMU-n, n ≥ 1)**: Obsolete. +- 3.2.76 **OTN network element (O.NE)**: Refer to the description in [ITU-T G.874]. +- 3.2.77 **optical overhead signal (OOS)**: Obsolete. +- 3.2.78 **optical physical section**: Obsolete. +- 3.2.79 **optical physical section of order n (OPSn)**: Refer to OPS in [ITU-T G.709]. +- 3.2.80 **optical supervisory channel (OSC)**: Refer to OSC in [ITU-T G.872]. +- 3.2.81 **optical transport hierarchy (OTH)**: Obsolete. +- 3.2.82 **optical transport module (OTM-n[r].m)**: Obsolete. +- 3.2.82.1 **OTM with full functionality (OTM-n.m)**: Obsolete. +- 3.2.82.2 **OTM with reduced functionality (OTM-0.m, OTM-nr.m)**: Obsolete. +- 3.2.83 **optical transport network**: [ITU-T G.709]. +- 3.2.84 **optical transport network node interface (ONNI)**: [ITU-T G.709]. +- 3.2.85 **optical transport unit-k (OTUk)**: Refer to OTU in [ITU-T G.709]. +- 3.2.86 **OTH multiplexing**: Obsolete. +- 3.2.87 **OTM overhead signal (OOS)**: Obsolete. +- 3.2.88 **OTN management network (O.MN)**: Refer to the description in [ITU-T G.874]. +- 3.2.89 **OTN management subnetwork (O.MSN)**: Refer to the description in [ITU-T G.874]. +- 3.2.90 **outgoing signal fail (OSF)**: Obsolete. +- 3.2.91 **overhead access (OHA)**: Obsolete. +- 3.2.92 **overhead information**: Obsolete. + +- 3.2.92.1 **client-specific overhead information:** Obsolete. +- 3.2.92.2 **auxiliary channel overhead information:** Obsolete. +- 3.2.92.3 **reserved overhead information:** Obsolete. +- 3.2.92.4 **trail termination overhead information:** Obsolete. +- 3.2.92.5 **unassigned overhead information:** Obsolete. +- 3.2.92.6 **network operator-specific overhead information:** Obsolete. +- 3.2.93 **protected domain:** [ITU-T G.808]. +- 3.2.94 **protection:** [ITU-T G.808]. +- 3.2.95 **protection class: trail protection:** [ITU-T G.808]. +- 3.2.96 **protection class: network connection protection:** [ITU-T G.808]. +- 3.2.97 **protection class: individual:** [ITU-T G.808]. +- 3.2.98 **protection class: group:** [ITU-T G.808]. +- 3.2.99 **protection communication channel:** [ITU-T G.808]. +- 3.2.100 **protection control:** [ITU-T G.808]. +- 3.2.101 **protection group:** [ITU-T G.808]. +- 3.2.102 **protection ratio:** [ITU-T G.808]. +- 3.2.103 **protection transport entity:** [ITU-T G.808]. +- 3.2.104 **resize multiframe (RMF):** Refer to the description in [ITU-T G.7044]. +- 3.2.105 **restoration:** [ITU-T G.808]. +- 3.2.106 **revertive (protection) operation:** [ITU-T G.808]. +- 3.2.107 **selector:** [ITU-T G.808]. + - 3.2.107.1 **merging selector:** [ITU-T G.808]. + - 3.2.107.2 **selective selector:** [ITU-T G.808]. +- 3.2.108 **severely errored second (SES):** [ITU-T G.8201]. +- 3.2.109 **signal:** Widely used in a general sense. +- 3.2.110 **signal degrade group (SDG):** [ITU-T G.808]. +- 3.2.111 **signal fail group (SFG):** [ITU-T G.808]. +- 3.2.112 **signal quality supervision:** Widely used in a general sense. +- 3.2.113 **sink node:** [ITU-T G.808]. +- 3.2.114 **source node:** [ITU-T G.808]. +- 3.2.115 **SRP-1:** [ITU-T G.808]. +- 3.2.116 **SRP-p:** [ITU-T G.808]. +- 3.2.117 **standby transport entity:** [ITU-T G.808]. +- 3.2.118 **steering:** [ITU-T G.808]. +- 3.2.119 **sublayer overhead/OAM (s):** Widely used in a general sense. +- 3.2.120 **subnetwork connection protection:** [ITU-T G.808]. +- 3.2.121 **subnetwork connection supervision:** Widely used in a general sense. + +- 3.2.122 **subnetwork interworking**: Widely used in a general sense. +- 3.2.123 **switch**: [ITU-T G.808]. +- 3.2.124 **switch event**: [ITU-T G.808]. +- 3.2.125 **switching time**: [ITU-T G.808]. +- 3.2.126 **tail-end**: [ITU-T G.808]. +- 3.2.127 **TCM control function (TCMC)**: [ITU-T G.798]. +- 3.2.128 **TCM control information (TCMCI)**: [ITU-T G.798]. +- 3.2.129 **TCM control point (TCMCP)**: [ITU-T G.798]. +- 3.2.130 **traffic signal**: Widely used in a general sense. +- 3.2.131 **transport entity**: [ITU-T G.800]. +- 3.2.132 **transport entity protection**: [ITU-T G.808]. +- 3.2.133 **user-network interface (UNI)**: Widely used in a general sense. +- 3.2.134 **wait-to-restore normal traffic signal #i (WtR)**: [ITU-T G.808]. +- 3.2.135 **wait-to-restore time**: [ITU-T G.808]. +- 3.2.136 **working transport entity**: [ITU-T G.808]. +- 3.2.137 **wrapping**: [ITU-T G.808]. + +## ITU-T Y-SERIES RECOMMENDATIONS + +### GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES + +| | | +|--------------------------------------------------------------------|----------------------| +| GLOBAL INFORMATION INFRASTRUCTURE | | +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | +| INTERNET PROTOCOL ASPECTS | | +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | +| IPTV over NGN | Y.1900–Y.1999 | +| NEXT GENERATION NETWORKS | | +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Enhancements to NGN | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Network control architectures and protocols | Y.2500–Y.2599 | +| Packet-based Networks | Y.2600–Y.2699 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | +| Carrier grade open environment | Y.2900–Y.2999 | +| FUTURE NETWORKS | Y.3000–Y.3499 | +| CLOUD COMPUTING | Y.3500–Y.3999 | +| INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES | | +| General | Y.4000–Y.4049 | +| Definitions and terminologies | Y.4050–Y.4099 | +| Requirements and use cases | Y.4100–Y.4249 | +| Infrastructure, connectivity and networks | Y.4250–Y.4399 | +| Frameworks, architectures and protocols | Y.4400–Y.4549 | +| Services, applications, computation and data processing | Y.4550–Y.4699 | +| Management, control and performance | Y.4700–Y.4799 | +| Identification and security | Y.4800–Y.4899 | +| Evaluation and assessment | Y.4900–Y.4999 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | 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b/marked/G/T-REC-G.973-201611-I_PDF-E/raw.md @@ -0,0 +1,960 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.973** + +(11/2016) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical fibre +submarine cable systems + +# --- **Characteristics of repeaterless optical fibre submarine cable systems** + +Recommendation ITU-T G.973 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.973 + +# Characteristics of repeaterless optical fibre submarine cable systems + +Recommendation ITU-T G.973 is concerned primarily with the system performance and interface requirements of repeaterless optical fibre submarine cable systems. It considers both single wavelength systems (SWS), wavelength division multiplexing systems (WDMS), and dense wavelength division multiplexing systems (DWDMs). It also covers the aspects related to the applications of discrete optical fibre amplifiers (OFAs) (power amplifiers, pre-amplifiers, remote optically pumped amplifiers) and/or distributed remotely pumped OFAs using Raman amplification. This edition of the Recommendation introduces a new power budget template for the implementation of coherent systems. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.973 | 1996-11-11 | 15 | 11.1002/1000/3831 | +| 2.0 | ITU-T G.973 | 2003-12-14 | 15 | 11.1002/1000/7068 | +| 3.0 | ITU-T G.973 | 2007-07-29 | 15 | 11.1002/1000/9158 | +| 4.0 | ITU-T G.973 | 2010-07-29 | 15 | 11.1002/1000/10883 | +| 5.0 | ITU-T G.973 | 2016-11-13 | 15 | 11.1002/1000/13117 | + +## Keywords + +Repeaterless optical fibre submarine cable systems, remote optically pumped amplifier (ROPA) + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2017 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 3 | +| 3.1 Terms defined elsewhere ..... | 3 | +| 3.2 Terms defined in this Recommendation ..... | 4 | +| 4 Abbreviations and acronyms ..... | 4 | +| 5 Conventions ..... | 6 | +| 6 Characteristics and performance of the system ..... | 6 | +| 6.1 Characteristics and performance of the digital line sections (DLS)..... | 6 | +| 6.2 Characteristics and performance of the optical sections ..... | 8 | +| 6.3 System reliability performance..... | 12 | +| 6.4 System capacity upgradeability ..... | 12 | +| 7 Characteristics and performance of the TTE ..... | 12 | +| 7.1 General ..... | 12 | +| 7.2 Transmission performance ..... | 12 | +| 7.3 Actions consequent to an alarm..... | 14 | +| 7.4 Automatic switching..... | 14 | +| 8 Characteristics and performance of the submarine cable ..... | 14 | +| 8.1 Dispersion mapping..... | 14 | +| 8.2 Dispersion management implementation ..... | 14 | +| Annex A – Implementation of repeaterless optical fibre submarine cable systems ..... | 16 | +| A.1 Introduction ..... | 16 | +| A.2 System configuration..... | 18 | +| A.3 Characteristics of the line signal..... | 21 | +| A.4 System operation ..... | 22 | +| A.5 Passive branching unit characteristics ..... | 22 | +| Annex B – Repeaterless optical fibre submarine cable systems using ROPA: Optical power budget between optical reference points S and R and line monitoring ..... | 24 | +| B.1 Remote optically pumped amplifiers (ROPAs)..... | 24 | +| B.2 Optical power budget for systems using ROPA..... | 24 | +| B.3 Line monitoring for pumping portion..... | 25 | +| Bibliography..... | 27 | + + + +## Recommendation ITU-T G.973 + +# Characteristics of repeaterless optical fibre submarine cable systems + +# 1 Scope + +This Recommendation is concerned primarily with the system performance and interface requirements of repeaterless optical fibre submarine cable systems; it considers both single wavelength systems (SWS), wavelength division multiplexing systems (WDMS) and dense wavelength division multiplexing systems (DWDMs). It also covers the aspects related to the applications of discrete optical fibre amplifiers (OFAs) as power amplifiers, pre-amplifiers and/or remote optically pumped amplifiers (ROPA) (either erbium-doped transmission fibres using remote pumping from the terminal or the distributed Raman amplification pumped from the terminal). + +The purpose of a repeaterless optical fibre submarine cable system is to establish transmission links between two or more terminal stations located in a restricted geographical area. + +A cable system connecting only two terminal stations may be termed an "optical fibre submarine cable link". When it connects more than two terminal stations, it may be termed an "optical fibre submarine cable network". + +In a repeaterless submarine cable system, no power feeding equipment (PFE) is necessary as there is no in-line OFA. + +As far as the branching unit devices are concerned, those considered in this Recommendation are the passive ones, therefore avoiding electronic components and supervisory and power feeding. + +Common implementation aspects of optical submarine cable systems for manufacturing, installing and maintenance are described in [ITU-T G.971]. [ITU-T G.978] contains common aspects of the characteristics of the optical fibre submarine cables. [ITU-T G.979] is also concerned with the characteristics of monitoring systems for repeaterless optical fibre submarine cable systems. + +The physical implementation of repeaterless optical fibre submarine cable systems and the implications of the use of ROPA are considered respectively in Annexes A and B. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a standalone document, the status of a Recommendation. + +- [ITU-T G.661] Recommendation ITU-T G.661 (2007), *Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems*. +- [ITU-T G.662] Recommendation ITU-T G.662 (2005), *Generic characteristics of optical amplifier devices and subsystems*. +- [ITU-T G.664] Recommendation ITU-T G.664 (2012), *Optical safety procedures and requirements for optical transport systems*. +- [ITU-T G.665] Recommendation ITU-T G.665 (2005), *Generic characteristics of Raman amplifiers and Raman amplified subsystems*. + +- [ITU-T G.692] Recommendation ITU-T G.692 (1998), *Optical interfaces for multichannel systems with optical amplifiers.* +- [ITU-T G.698.1] Recommendation ITU-T G.698.1 (2009), *Multichannel DWDM applications with single-channel optical interfaces.* +- [ITU-T G.701] Recommendation ITU-T G.701 (1993), *Vocabulary of digital transmission and multiplexing, and pulse code modulation (PCM) terms.* +- [ITU-T G.702] Recommendation ITU-T G.702 (1988), *Digital hierarchy bit rates.* +- [ITU-T G.703] Recommendation ITU-T G.703 (2016), *Physical/electrical characteristics of hierarchical digital interfaces.* +- [ITU-T G.707] Recommendation ITU-T G.707/Y.1322 (2007), *Network node interface for the synchronous digital hierarchy (SDH).* +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016), *Interfaces for the optical transport network* +- [ITU-T G.780] Recommendation ITU-T G.780/Y.1351 (2010), *Terms and definitions for synchronous digital hierarchy (SDH) networks.* +- [ITU-T G.821] Recommendation ITU-T G.821 (2002), *Error performance of an international digital connection operating at a bit rate below the primary rate and forming part of an Integrated Services Digital Network.* +- [ITU-T G.823] Recommendation ITU-T G.823 (2000), *The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy.* +- [ITU-T G.825] Recommendation ITU-T G.825 (2000), *The control of jitter and wander within digital networks which are based on the synchronous digital hierarchy (SDH).* +- [ITU-T G.826] Recommendation ITU-T G.826 (2002), *End-to-end error performance parameters and objectives for international, constant bit-rate digital paths and connections.* +- [ITU-T G.828] Recommendation ITU-T G.828 (2000), *Error performance parameters and objectives for international, constant bit-rate synchronous digital paths.* +- [ITU-T G.921] Recommendation ITU-T G.921 (1988), *Digital sections based on the 2048 kbit/s hierarchy.* +- [ITU-T G.955] Recommendation ITU-T G.955 (1996), *Digital line systems based on the 1544 kbit/s and the 2048 kbit/s hierarchy on optical fibre cables.* +- [ITU-T G.957] Recommendation ITU-T G.957 (2006), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy.* +- [ITU-T G.959.1] Recommendation ITU-T G.959.1 (2016), *Optical transport network physical layer interfaces.* +- [ITU-T G.971] Recommendation ITU-T G.971 (2016), *General features of optical fibre submarine cable systems.* +- [ITU-T G.972] Recommendation ITU-T G.972 (2016), *Definition of terms relevant to optical fibre submarine cable systems.* +- [ITU-T G.975] Recommendation ITU-T G.975 (2000), *Forward error correction for submarine systems.* +- [ITU-T G.975.1] Recommendation ITU-T G.975.1 (2004), *Forward error correction for high bit-rate DWDM submarine systems.* + +- [ITU-T G.978] Recommendation ITU-T G.978 (2010), *Characteristics of optical fibre submarine cables.* +- [ITU-T G.979] Recommendation ITU-T G.979 (2016), *Characteristics of monitoring systems for optical fibre submarine cable systems.* +- [ITU-T G.8201] Recommendation ITU-T G.8201 (2011), *Error performance parameters and objectives for multi-operator international paths within optical transport networks.* +- [ITU-T G.8251] Recommendation ITU-T G.8251 (2010), *The control of jitter and wander within the optical transport network (OTN).* +- [IEC 60825-1] IEC 60825-1 (2014), *Safety of laser products – Part 1: Equipment classification and requirements.* +- [IEC 60825-2] IEC 60825-2 (2006), *Safety of laser products – Part 2: Safety of optical fibre communication systems (OCFS).* + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **digital line section (DLS)** [ITU-T G.701] +- 3.1.2 **double armoured cable** [ITU-T G.972] +- 3.1.3 **intermediate terrestrial interface (ITI)** [ITU-T G.972] +- 3.1.4 **multiplex section overhead (MSOH)** [ITU-T G.780] +- 3.1.5 **optical fibre amplifier (OFA)** [ITU-T G.661] +- 3.1.6 **receive main path interface reference point (MPI-R)** [ITU-T G.959.1] +- 3.1.7 **rock armoured cable** [ITU-T G.972] +- 3.1.8 **S', R' reference points** [ITU-T G.662] +- 3.1.9 **single armoured cable** [ITU-T G.972] +- 3.1.10 **source main path interface reference point (MPI-S)** [ITU-T G.959.1] +- 3.1.11 **submarine cable optical interface (SCOI)** [ITU-T G.977] +- 3.1.12 **submarine electro-optic interface (SEOI)** [ITU-T G.977] +- 3.1.13 **synchronous digital hierarchy (SDH)** [ITU-T G.780] +- 3.1.14 **synchronous transport module (STM)** [ITU-T G.780] +- 3.1.15 **terrestrial interface (TI)** [ITU-T G.972] +- 3.1.16 **time varying system penalty (TVSP)** [ITU-T G.977] + +![Figure 1: Representation of optical line system interfaces (multichannel system). The diagram shows a multichannel optical system with two terminal stations connected by a DLS (Dense Line System) fiber. On the left, multiple transmitters (Tx1, Tx2, ..., TxNλ) are connected to an Optical mux/demux via switches S1, S2, ..., Sn. The mux/demux is connected to the DLS via an MPI-S (Multi-Protocol Interface - Sender) and an SCOI (Submarine Cable Optical Interface). The DLS is connected to the right station via an MPI-R (Multi-Protocol Interface - Receiver) and an SCOI. The right station's Optical mux/demux is connected to multiple receivers (Rx1, Rx2, ..., RxNλ) via switches R1, R2, ..., Rn. Both stations have a SEOI (Submarine Cable Optical Interface) connection. The diagram is labeled G.973(16)_F01.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Figure 1: Representation of optical line system interfaces (multichannel system). The diagram shows a multichannel optical system with two terminal stations connected by a DLS (Dense Line System) fiber. On the left, multiple transmitters (Tx1, Tx2, ..., TxNλ) are connected to an Optical mux/demux via switches S1, S2, ..., Sn. The mux/demux is connected to the DLS via an MPI-S (Multi-Protocol Interface - Sender) and an SCOI (Submarine Cable Optical Interface). The DLS is connected to the right station via an MPI-R (Multi-Protocol Interface - Receiver) and an SCOI. The right station's Optical mux/demux is connected to multiple receivers (Rx1, Rx2, ..., RxNλ) via switches R1, R2, ..., Rn. Both stations have a SEOI (Submarine Cable Optical Interface) connection. The diagram is labeled G.973(16)\_F01. + +**Figure 1 – Representation of optical line system interfaces (multichannel system)** + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 branching unit (BU):** A passive optical submarine piece of equipment inserted into the submarine portion of an optical fibre submarine cable network where the interconnection of more than two cable sections is necessary. + +**3.2.2 cable jointing box:** Box to be installed on optical submarine or land cable, in case of junction or repair of the cable itself, which is designed to provide mechanical, electrical and optical continuity, waterproofness and storage of the fibre splices and fibre extra length. + +**3.2.3 distributed Raman amplifier (DRA):** An OFA using the transmission fibre, as an amplifier medium, that is pumped from the terminal station. The gain is obtained all along the fibre (therefore distributed) using the Raman properties of the fibre until sufficient pump power is available. + +**3.2.4 remote optically pumped amplifier (ROPA):** An OFA consisting of a section of erbium doped fibre that is activated by a pump beam sent from the terminal station. + +**3.2.5 terminal transmission equipment (TTE):** The equipment included into the terrestrial portion of an optical fibre submarine cable system for terminal transmission multiplexing and demultiplexing operations, coding and converting the incoming tributaries into the optical line signal, converting and decoding the received optical line signal in the outgoing tributaries, performing cable termination operations. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------------|--------------------------------------------------------------------------| +| ASE | Amplified Spontaneous Emission | +| BER | Bit Error Ratio | +| BOL | Beginning Of Life | +| BU | Branching Unit | +| COTDR | Coherent Optical Time-Domain Reflectometry | +| CSF | Cut-off Shifted single mode Fibre | +| DCF | Dispersion Compensation single mode Fibre | +| DC PDM-BPSK | Dual Carrier Polarization-Division-Multiplexed Binary-Phase-Shift-Keying | + +| | | +|--------------|---------------------------------------------------------------------------------------| +| DC PDM-DBPSK | Dual Carrier Polarization-Division-Multiplexed Differential Binary-Phase-Shift-Keying | +| DLS | Digital Line Section | +| DRA | Distributed Raman Amplifier | +| DSF | Dispersion Shifted single mode Fibre | +| DWDM | Dense Wavelength Division Multiplexing | +| DWDMS | Dense Wavelength Division Multiplexing System | +| EDF | Erbium Doped Fibre | +| EOL | End Of Life | +| ITI | Intermediate Terrestrial Interface | +| MPI-R | Receive Main Path Interface reference point | +| MPI-S | Source Main Path Interface reference point | +| MSOH | Multiplex Section Overhead | +| MTC | Marinized Terrestrial Cable | +| NDSF | Non Dispersion Shifted single mode Fibre | +| NRZ | No Return to Zero | +| NZDSF | Non-Zero Dispersion Shifted single mode Fibre | +| OFA | Optical Fibre Amplifier | +| OSNR | Optical Signal-to-Noise Ratio | +| OTDR | Optical Time-Domain Reflectometry | +| OTN | Optical Transport Network | +| PDG | Polarization Dependent Gain | +| PDH | Plesiochronous Digital Hierarchy | +| PDL | Polarization Dependent Loss | +| PDM-DQPSK | Polarization-Division-Multiplexed Differential Quadrature-Phase-Shift-Keying | +| PDM-QPSK | Polarization-Division-Multiplexed Quadrature-Phase-Shift-Keying | +| PFE | Power Feeding Equipment | +| PMD | Polarization Mode Dispersion | +| ROPA | Remote Optically Pumped Amplifier | +| SCOI | Submarine Cable Optical Interface | +| SDH | Synchronous Digital Hierarchy | +| SEOI | Submarine Electro-Optic Interface | +| SMF | Single-Mode Fibre | +| STM | Synchronous Transport Module | +| SWS | Single Wavelength System | +| TI | Terminal Interface | + +| | | +|-------|------------------------------------------------| +| TTE | Terminal Transmission Equipment | +| WDM | Wavelength Division Multiplexing | +| WDMS | Wavelength Division Multiplexing System | +| WNZDF | Wideband Non-Zero Dispersion single-mode Fibre | + +# 5 Conventions + +In this Recommendation, FFS stands for 'for further study'. + +# 6 Characteristics and performance of the system + +## 6.1 Characteristics and performance of the digital line sections (DLS) + +The digital line sections provided by the system shall be in accordance with the relevant Recommendations. + +### 6.1.1 Characteristics of the digital signals at the system interface, at intermediate terrestrial interface (ITI) and terminal interface (TI) + +For TI, the digital signals should comply, as applicable, with [ITU-T G.702], [ITU-T G.703], [ITU-T G.707], [ITU-T G.709], [ITU-T G.957] and [ITU-T G.959.1]. + +At ITI, it is recommended that the digital signals be compliant with the physical parameters described in [ITU-T G.957] and [ITU-T G.959.1]. + +Several interfaces with different bit rates may coexist for one single optical fibre submarine cable system. + +### 6.1.2 Overall error performances at TI + +The error performances of an optical fibre submarine cable system should conform to the relevant Recommendations for the design life of the systems: + +- for plesiochronous digital hierarchy (PDH) interfaces: [ITU-T G.821] for systems designed prior to December 2002 and [ITU-T G.826] for the later systems; +- for synchronous digital hierarchy (SDH) interfaces: [ITU-T G.826] for systems designed prior to March 2000 and [ITU-T G.828] for the later systems; +- for optical transport network (OTN) interfaces: [ITU-T G.8201]. + +For PDH systems, the relevant parameters are severely errored seconds and errored seconds. They are derived from [ITU-T G.821] and [ITU-T G.826] in conjunction with the performances at 64 kbit/s on a per km basis. Information on the mapping of system performances at the 64-kbit/s level is given in Annex D of the 1988 version of [ITU-T G.821]. + +For SDH systems, the relevant parameters are severely errored seconds and errored seconds. They are derived from [ITU-T G.826] and [ITU-T G.828]. + +For OTN systems, the relevant parameters are severely errored seconds, background block error and errored block. They are derived from [ITU-T G.8201]. + +### 6.1.3 System availability at TI + +For PDH systems: + +- the unavailable time definition is derived from Annex A of [ITU-T G.821]; +- as per Annex A of [ITU-T G.821] and Annex A of [ITU-T G.826], a period of unavailable time begins when the bit error ratio (BER) in each second is worse than $1 \times 10^{-3}$ for a period of ten consecutive seconds. These ten seconds are considered to be unavailable time. + +The period of unavailable time terminates when the BER in each second is better than $1 \times 10^{-3}$ for a period of ten consecutive seconds. These ten seconds are considered to be available time. + +For SDH systems: + +- the unavailable time definition is derived from [ITU-T G.826] (for systems designed prior to March 2000) and [ITU-T G.828] (for systems designed after March 2000). + +For OTN systems: + +- the unavailable time definition is derived from [ITU-T G.8201]. + +The system availability depends on the combined aspects of the reliability performance, the maintainability performance and the maintenance support performance of the system equipment, and particularly of the system terminal equipment. + +The unavailability specification applies to unavailable time caused by system component failure, and includes, for example, laser switching, terminal faults and supervisory and maintenance operation leading to interruptions of ten seconds or longer. It does not include faults caused by trawlers or other external factors including terminal transmission equipment (TTE) power feeding and any period during which the system is de-powered for repair. Similarly, faults requiring ship intervention are not included in the unavailable time calculation. + +### **6.1.4 Jitter performances at TI and ITI** + +The jitter performances of an optical fibre submarine cable system should follow [ITU-T G.823], [ITU-T G.825] and [ITU-T G.8251] and other relevant Recommendations at ITI and TI for the system design life. + +### **6.1.5 Performance allocation between portions of the system** + +The end-to-end performance for a given digital line section (DLS) is obtained by multiplying the specified per-km allocation by the DLS length. When it is necessary to allocate performance degradation to various portions in the DLS, an amount corresponding to a fixed length (to be determined) is allocated to each station terminal equipment, and the submarine portion is allocated on a per-km basis at an amount equal to the difference between the DLS specification and the terminal allocation. + +### **6.1.6 DLS independence** + +It is recommended that any failure, maintenance operation, supervisory operation, etc., on any DLS should have no impact on the specified performances of any other DLS in the system. In particular: + +- a) for wavelength division multiplexing system (WDMS) and dense wavelength division multiplexing system (DWDMs): + - i) any failure of up to half the number of wavelengths should have no traffic disruption on any of the remaining wavelengths; +- b) for single wavelength system (SWS), wavelength division multiplexing system (WDMS) and dense wavelength division multiplexing system (DWDMs): + - i) any failure on one fibre pair should have no effect on the other fibre pairs in the system; + - ii) any failure on any tributary at any level of multiplexing or demultiplexing (optical or electrical) in the system should have no effect on the remaining parts of the system. + +The short-term effects of transients should normally be considered tolerable, in their unlikely event. + +## 6.2 Characteristics and performance of the optical sections + +### 6.2.1 Optical power budget + +The optical performance of the optical section is characterized by its optical power budget, which is the difference between the mean optical powers, expressed in dBm, at the two ends of a submersible optical fibre cable section. This can be obtained taking into account the characteristics of the optical components in the equipment at both ends of the cable section. The optical power budget can be used to calculate the length of the submersible optical fibre cable section which permits fulfilment of the overall error performance requirement for the digital line section in the submarine optical fibre cable system. + +Several approaches can be used to calculate the optical power budget. They can be classified into worst-case approach, statistical approach and semi-statistical approach. A detailed example of these different approaches is given in [b-ITU-T G.Sup39]. + +The optical power budget should take into account part or all of the following parameters: + +- receiver sensitivity (dBm): +the mean optical power in the optical signal modulated by a pseudo-random electrical signal with a specified mark density at the input of the optical fibre pigtail of a receiver, below which the receive equipment would exhibit a bit error ratio higher than $10^{-12}$ ; +- receiver optical overload (dBm): +the mean optical power in the optical signal modulated by a pseudo-random electrical signal with a specified mark density at the input of the optical fibre pigtail of a receiver, above which the receive equipment would exhibit a bit error ratio higher than $10^{-12}$ ; +- receiver dynamic range (dB): +the difference between the receiver optical overload and the receiver sensitivity; +- mean launched power (dBm): +the mean optical power in the optical line signal at the output of the optical fibre pigtail of the transmitter; +- the equipment internal loss (dB); +- the optical section loss (dB); +- the system performance penalty (dB): +taking into account the difference between the performance of an "ideal" line terminal equipment and a "real" line terminal equipment associated with its full cable section. The phenomena to be considered in its value include optical feedback, signal patterning effects, non-ideal equalization, partition noise, chromatic dispersion, polarization mode dispersion, non-linearities, ASE noise, etc.; +- the ageing margin (dB): +taking into account the variation of the optical component attenuation, including that of fibres, due to ageing during the system design life; +- the repair provision (dB): +taking into account the possible increase of attenuation of the cable fibre due to cable repair during the system design life. The value of the repair provision depends on the sea depth. The repair provision for the shallow water portions can be obtained as the product of a repair number and of the mean attenuation per repair, equal to the attenuation of two cable joints with the addition of the loss of a length of cable proportional to the sea depth; +- an unassigned margin (dB): +a provision for phenomena which cannot be precisely foreseen; + +– the overload margin (dB): + +the minimum difference between the receive power and the receive optical overload for a given BER. + +An important parameter which should be specified to help in system commissioning is the guaranteed margin that is the minimum margin in the power budget of the optical section which should be measured at a specific point in time, i.e., system assembly in factory or on board the cable ship, and which is equal to the sum of ageing, repair and unassigned margins. Examples on margins that can be taken into account in the power budget calculation are given in [b-ITU-T G.Sup41]. + +### 6.2.2 Optical power budget for high bit rate coherent system + +The power budget tables for high bit rate coherent system should compute margins that should be considered as a minimum requirement for the system at BOL. These margins should be expressed in terms of a Q factor value. The suppliers should provide, as a minimum, the values of the parameters used to compute the power budget and specify all necessary complementary relevant information such as: channel power, optical signal-to-noise-ratio and method for obtaining TTE Q factor as function of OSNR. + +An example of a possible power budget template is shown in Table 1. + +**Table 1 – An example of a possible coherent power budget template** + +| Item | Description | dB/0.1 nm | +|------|--------------------------------------------------------------|-----------| +| A | BOL OSNR at full loading 1 (XX dBm channel power) | | +| B | EOL OSNR at full loading 1 (XX dBm channel power) | | +| | | | +| Item | Description | Q (dB) | +| 1 | Back-to-back Q at BOL OSNR | | +| 2 | Propagation impairments | | +| 3 | Other impairments | | +| 3.1 | Non-optimal optical pre-emphasis | | +| 3.2 | Wavelength tolerance impairment | | +| 3.3 | Mean penalty due to polarization-dependent effects | | +| 3.4 | Manufacturing and environmental impairment | | +| 3.5 | Unspecified impairment | | +| 4 | Margin for Q time variations ( $5\sigma$ ) | | +| 5 | BOL segment Q | | +| 6 | Repair and ageing impairments | | +| 6.1 | Cable repair and ageing | | +| 6.2 | TTE ageing | | +| 7 | EOL segment Q | | +| 8 | FEC limit | | +| 9.1 | Customer segment EOL margin | | +| 9.2 | Extra margin | | +| 10 | Commissioning limit | | + +1 Full loading implies design capacity. + +Table 1 should be completed as follows: + +- Line A: The BOL OSNR is given for the full loading condition with a specified channel power. The supplier should provide key parameters for the system that would allow estimation of OSNR for the given channel power. For new system builds, this OSNR value is given as a reference only. +- Line B: The EOL OSNR is given for the full loading condition with a specified channel power. The supplier should provide key parameters for the system that would allow estimation of OSNR for the given channel power. For new system builds, this OSNR value is given as a reference only. +- Line 1: The back-to-back (i.e., no fibre propagation) Q factor should be specified at the OSNR given in line A, for a TTE with average performance. The supplier should provide the method for obtaining TTE Q as function of OSNR. +- Line 2: The propagation impairment is specified as follows: + - Through measurement or simulation of a transmission representative of the SDLS, obtain the expected Q factor after propagation (including all modem implementation penalties), at the OSNR listed in line A for a TTE with average performance. If Line 1 lists TTE Q for a single channel loading, then Line 2 should include penalty due to the cross-talk between WDM channels. + - Subtract the propagated Q factor from the back-to-back Q factor in line 1. +- Line 3: The supplier margin allocations are specified as follows: + - Lines 3.1: The non-optimal pre-emphasis impairment corresponds to the imperfect Q factor equalization over the full spectral range. + - Line 3.2: The wavelength tolerance impairment corresponds to the degradation due to the non-optimal wavelength setting. + - Line 3.3: Mean penalty due to polarization-dependent effects such as PDL, PDG, and PMD. + - Line 3.4: The manufacturing and environmental impairment provides margin for normal product fluctuations due to the manufacturing process and environmental conditions. For new system builds, this parameter includes impairments both from the DLS transmission path and the TTE. For system upgrades, this parameter includes only impairments from the TTE. + - Line 3.5: Unspecified impairment is allocated for any other impairment not listed in lines 3.1 to 3.4. +- Line 4: The Q-time variations margin (or time varying system penalty (TVSP)) defines an additional impairment due to performance fluctuations around the mean performance. Five standard deviations of Q factor should be allocated. +- Line 5: The BOL segment Q is defined as: + - Line 5 = line 1 – (sum of line 2 to lines 3.1-3.5) – line 4 +- Lines 6.1 and 6.2: Allocation for repairs and ageing in Q (dB). The supplier should detail method of estimating this penalty and how it relates to the OSNR degradation defined as the difference between Line A and Line B. +- Line 7: EOL segment Q is defined as: + - Line 7 = line 5 – (sum of lines 6.1 and 6.2) +- Line 8: FEC Limit in Q (dB) for compliance with [ITU-T G.826] or [ITU-T G.8201] after FEC correction. $10^{-13}$ is commonly used as BER after FEC correction in submarine systems. + +- Line 9.1: Customer margin is the specified margin required at EOL by the cables' customer. +- Line 9.2: Extra margin is the margin available after all repair, ageing and customer-required margins are allocated, and is calculated as the difference between the BOL segment Q and the commissioning limit. +- Line 10: This line gives the contractual commissioned Q limit for each DLS. If performance of each channel is measured to be above the commissioning limit, then adequate margin for repair, ageing, and customer provisions have been demonstrated. + +Beside the power budget tables, the loss budget table should also be provided by suppliers to specify the loss at BOL and EOL. + +An example of a possible loss budget template is shown in Table 2. + +**Table 2 – An example of a possible loss budget template** + +| Item | Description | Unit | Value | +|------|-----------------------------------------|-------|---------------------------------------------| +| 1.1 | Submarine cable length | km | | +| 1.2 | Submarine cable attenuation coefficient | dB/km | | +| 1.3 | Land cable length | km | | +| 1.4 | Land cable attenuation coefficient | dB/km | | +| 1.5 | Manufacturing and installation margin | dB | | +| 1.6 | Cable ageing | dB | | +| 1.7 | Repair margin | dB | | +| 1.8 | Unassigned margin | dB | | +| 1.9 | Total segment loss for BOL | dB | $1.1 \cdot 1.2 + 1.3 \cdot 1.4 + 1.5 + 1.8$ | +| 1.10 | Total segment loss for EOL | dB | $1.6 + 1.7 + 1.9$ | + +NOTE – Item 1.5 Manufacturing and installation margin is for the total segment. + +### 6.2.3 Optical fibre amplifiers applications + +The available power budget can be increased considerably by adding optical fibre amplifiers (OFAs) to the terminal equipment. They may be used as power amplifiers inserted just after the laser transmitter to increase the terminal output power or pre-amplifiers inserted just before the optical receiver to reduce the minimum optical signal power at the input of a composite receiver (pre-amplifier plus terminal receiver). In general, system enhancement can be achieved by power amplifier only, pre-amplifier only, or a combination of both. In these cases, the definition of the optical power budget is given taking into account the parameters described in clause 6.2.1 between the optical reference points S'-R, S-R' and S'-R', where the definitions of S' and R' are given in [ITU-T G.662]. + +Moreover, the application of remote optically pumped amplifiers (ROPAs) and distributed Raman amplifiers (DRAs) is also considered. A ROPA consists of a section of erbium doped fibre (EDF) pumped from the terminal station at an appropriate wavelength, whereas the DRA uses the fibre itself as an amplification medium and requires the fibre pumped from the terminal station at appropriate wavelength. There is no electrical power propagation into the submarine portion. This technique can be employed at either the transmit or the receive side of a link although it is generally considered more efficient at the receive side. Generic characteristics of DRAs are given in [ITU-T G.665]. In the case of the use of ROPAs or DRAs, the definition of the optical power budget, given on the basis of the parameters listed in clause 6.2.1, cannot be applied, as there is an amplification of the optical signal before the terminal end. The optical power budget is therefore no + +longer equal to the power difference between the two ends but to the allocable loss between the two ends of the link (see Annex B). + +The possible system configurations are shown in Figure A.2. + +## **6.3 System reliability performance** + +The reliability of the submarine portion of an optical fibre submarine cable system is generally characterized by: + +- the expected number of repairs requiring intervention by a cable ship and due to system component failures during the system design life (e.g., splices, branching unit (BU), transitions, etc.). The usual requirement for the reliability of a repeaterless system is less than one failure requiring cable ship intervention during the system design life; +- the system design life, which is the period of time over which the optical fibre submarine cable system is designed to be operational in conformance with its performance specification. Usually, the system design life is a period of 25 years starting at the provisional acceptance date of the system, i.e., the date following installation when the system is claimed to be compliant with the performance specifications. + +## **6.4 System capacity upgradeability** + +It may be advantageous to increase the transmission capacity by increasing the signal bit rate and/or the number of transmission channels (WDMS or DWDMs). Such upgrading can be beneficial because the reuse of cables can be achieved cost-effectively over the equipment's long life, typically 25 years. + +Bit-rate upgradeability demands that systems be constructed with cables optimized for the higher bit rate, while the lower bit-rate TTE may be initially used. Even after upgrading, the bit rate of TTE output must comply with SDH or OTN specifications to ensure compatibility with standard terrestrial equipment. + +Upgradeability also demands that the initially installed cable be capable of carrying the maximum number of channels expected in the future. + +Upgrading by increasing signal bit rate or by adding more channels is much different from many viewpoints of system design, including the post-amplifier output power, pre-amplifier input power, power budget, signal-to-noise ratio, fibre chromatic dispersion, fibre polarization mode dispersion, and fibre non-linearities. It is therefore recommended that the systems be designed properly considering the possibility of future upgrades. + +# **7 Characteristics and performance of the TTE** + +## **7.1 General** + +The terminal equipment is designed to assemble the tributaries for transmission over the optical fibre submarine cable system and to provide monitoring and maintenance facilities. + +## **7.2 Transmission performance** + +### **7.2.1 Characteristics of the digital signal at the TI** + +The digital signal at the TI should be in accordance with [ITU-T G.703], [ITU-T G.709], [ITU-T G.957] and [ITU-T G.959.1]. + +### 7.2.2 Characteristics of the signal at the submarine cable optical interface (SCOI) and submarine electro-optic interface (SEOI) + +The signal at the SCOI and SEOI interfaces should be in agreement with the power budget of the optical section. The following minimum list of parameters should be specified. + +| Parameters | Units | Defined in | +|---------------------------------------------------------|-------|-----------------------------------| +| General information | | | +| Bit rate/line coding of optical tributary signals | – | clause 7.2.1.2 of [ITU-T G.959.1] | +| Modulation format | – | FFS | +| Maximum number of channels | – | clause 7.2.1.1 of [ITU-T G.959.1] | +| Maximum bit error ratio | – | clause 7.2.1.3 of [ITU-T G.959.1] | +| Operating wavelength range | nm | clause 7.2.2.6 of [ITU-T G.959.1] | +| Fibre type | – | clause 7.2.1.4 of [ITU-T G.959.1] | +| Interface at point S (transmit side of SEOI) | | | +| Channel spacing | GHz | clause 7.2.2.4 of [ITU-T G.959.1] | +| Maximum mean channel output power | dBm | clause 7.2.1 of [ITU-T G.698.1] | +| Minimum mean channel output power | dBm | clause 7.2.1 of [ITU-T G.698.1] | +| Central frequency | THz | clause 7.2.2.3 of [ITU-T G.959.1] | +| Maximum central frequency deviation | GHz | clause 7.2.2.5 of [ITU-T G.959.1] | +| Minimum channel extinction ratio | dB | clause 7.2.5 of [ITU-T G.698.1] | +| Interface at point MPI-S (transmit side of SCOI) | | | +| Maximum mean total output power | dBm | clause 7.2.2.2 of [ITU-T G.959.1] | +| Maximum channel power difference | dB | clause 7.2.4.4 of [ITU-T G.959.1] | +| Channel signal-to-noise ratio | dB | FFS | +| Interface at point MPI-R (receive side of SCOI) | | | +| Maximum mean total input power | dBm | clause 7.2.4.3 of [ITU-T G.959.1] | +| Maximum channel power difference | dB | clause 7.2.4.4 of [ITU-T G.959.1] | +| Channel signal-to-noise ratio | dB | FFS | +| Maximum cumulated chromatic dispersion | ps/nm | FFS | +| Maximum differential group delay | ps | clause 7.2.3.7 of [ITU-T G.959.1] | +| Interface at point R (receive side of SEOI) | | | +| Minimum channel back-to-back Q factor | dB | clause 7.2.3 | +| Maximum mean channel input power | dBm | clause 7.4.1 of [ITU-T G.698.1] | +| Receiver sensitivity | dBm | clause 7.4.2 of [ITU-T G.698.1] | + +### 7.2.3 Minimum (channel) back-to-back Q factor + +- The minimum (channel) back-to-back Q factor at reference point MPI-R is the minimum Q factor value for all channels when the MPI-S and MPI-R interfaces are directly connected (back-to-back configuration). An optical attenuator could be used between the two interfaces so that the input optical signal at MPI-R is compliant with nominal working conditions. + +### 7.2.4 Jitter performances + +The jitter performances of the TTE of an optical fibre submarine cable system should be in compliance with [ITU-T G.823], [ITU-T G.825], [ITU-T G.8251] and other relevant Recommendations throughout the system design life. + +## **7.3 Actions consequent to an alarm** + +The terminal equipment should detect fault conditions and perform consequent actions as detailed in the relevant Recommendations. Alarm indications that could be taken into consideration for optical amplifiers utilized in the system should be limited to the critical parameters (e.g., input and output signal optical power, operating conditions of the pump laser, such as bias current and temperature). The laser safety aspects should be in accordance with [ITU-T G.664], [IEC 60825-1] and [IEC 60825-2]. + +## **7.4 Automatic switching** + +Where automatic switching is used to meet the overall availability requirement: + +- the traffic degradation due to switching should be minimized and compatible with the overall system performance; +- indication should be given of the in-service equipment; +- manual override of the automatic switching should be feasible with a minimal degradation of system performance. + +The standby equipment is recommended to be kept operating and monitored like the in-service equipment. + +# **8 Characteristics and performance of the submarine cable** + +The recommended characteristics and performance of the submarine cable are given in [ITU-T G.978]. + +For certain repeaterless optical fibre submarine systems (usually for lakes or river crossings), the submarine cable or a part of it can be replaced by a marinized terrestrial cable (MTC). + +Repeated submarine cables can be used in all underwater applications, and repeaterless submarine cables in all MTC applications. + +## **8.1 Dispersion mapping** + +The dispersion map is the principal tool for describing the chromatic dispersion characteristics of a system. Cumulative dispersion is defined as the dispersion measured between the output of the terminal transmitter and any other point in the optical path. The dispersion map is the plot of local chromatic dispersion, for a given operating wavelength, as a function of distance from the optical transmitter to the optical receiver. The dispersion map will depend on the number of wavelengths in the system. + +## **8.2 Dispersion management implementation** + +The design of the dispersion map for each optical section must be in accordance with the transmission requirements (limitation of non-linear effects, pulse broadening, etc.). + +Residual cumulative dispersion for each wavelength may be compensated to zero by using a length of equalization fibre or other passive dispersion compensation devices at the transmit (pre-compensation) and/or receive side (post-compensation) in TTE. + +For 100 Gbit/s coherent systems with large chromatic dispersion tolerance, the optical dispersion compensation may not be needed. + +The system design should take into consideration all causes of variation from the planned dispersion map, both random and systematic, including, but not limited to: + +- uncertainty in the measurements of zero dispersion wavelength, dispersion and dispersion slope of constituent dispersion shifted single mode fibre (DSF), non dispersion shifted + +single mode fibre (NDSF), dispersion compensation fibre (DCF), non-zero dispersion shifted single mode fibre (NZDSF), cut-off shifted single mode fibre (CSF), wideband non-zero dispersion single-mode fibre (WNZDF), negative slope fibres, EDF, etc.; + +- uncertainty in temperature, pressure, and strain coefficients of these fibres in the cable and pressure vessels; +- uncertainty of the exact temperature and strain of these fibres during dispersion measurements; +- uncertainty of the temperature of the installed fibre; +- uncertainty resulting from reordering and "random" selection of portions of fibre sets in the assembly of elementary cable sections; +- ageing; +- repair operations. + +# Annex A + +## Implementation of repeaterless optical fibre submarine cable systems + +(This annex forms an integral part of this Recommendation.) + +## A.1 Introduction + +This annex outlines various aspects of the submarine cable system practice, as commonly employed in repeaterless systems, taking into account the OFAs application as power amplifiers and pre-amplifiers. + +Typical system parameters are illustrated in Table A.1 up to 5 Gbit/s with single wavelength and in Table A.2 beyond this bit rate and in Table A.3 with wavelength division multiplexing systems (WDMS). + +The information provided in this annex is intended as a guide to current practice and is not intended as a recommendation relating to existing or future systems. + +**Table A.1 – Illustrative system parameters of repeaterless optical fibre submarine cable systems up to 5 Gbit/s and single wavelength** + +| Systems | 560 M (PDH) | 622 M (SDH) | 2488 M (SDH) | 4977 M (SDH) | +|---------------------------------------|---------------------------------------|-----------------------------------------------------------------|------------------------------|------------------------------| +| | 4 × 140
[Mbit/s] | 4 × 140/155
[Mbit/s] | 16 × 140/155
[Mbit/s] | 32 × 140/155
[Mbit/s] | +| Transmission capacity (ch. 64 kbit/s) | 7'560-7'680 | 7'560-7'680 | 30'240-30'720 | 60'480-61'440 | +| Information bit rate [Mbit/s] | ~560 | ~560 | ~2'240 | ~4'480 | +| Line bit rate [Mbit/s] (Note 3) | ~591 | ~622 | ~2'488 | ~4'977 | +| Line code (Note 2) | Max. flexibility | Scrambled NRZ (SDH) (Note 2) | Scrambled NRZ (SDH) (Note 2) | Scrambled NRZ (SDH) (Note 2) | +| Maximum system length [km] (Note 1) | >120 | >120 | >100 | >80 | +| Water depth [m] | Down to ~4'000 | | | | +| Fibre type | ITU-T G.652; ITU-T G.653; ITU-T G.654 | | | | +| Operating wavelength [nm] | ~1'550 | | | | +| System design life [year] | 25 | | | | +| Reliability (Note 4) | <1 repair in 25 years | | | | +| Error performance | ITU-T G.821 | ITU-T G.826 | | | +| Jitter | ITU-T G.823 | ITU-T G.825 (optical interfaces)
FFS (electrical interfaces) | | | + +**Table A.1 – Illustrative system parameters of repeaterless optical fibre submarine cable systems up to 5 Gbit/s and single wavelength** + +| | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NOTE 1 – The maximum system length is only indicative. The length can be increased considerably by using both non-standard PDH and SDH systems or optical booster amplifiers and/or optical pre-amplifiers. Remote optically pumped amplifiers can also be used for increasing the length (see Figure A.2). | +| NOTE 2 – In SDH systems, scrambled no return to zero (NRZ) code is used. In PDH systems, maximum flexibility is given to the line code to be adopted. It is also possible to combine these line codes with error correction coding in order to improve the system performances. | +| NOTE 3 – For PDH systems, the line bit-rate value is only indicative. | +| NOTE 4 – Refer to clause 6.3. | +| NOTE 5 – It will be possible to consider WDM technology to increase the transmission capacity and network flexibility of the systems. System parameters of repeaterless optical submarine cable systems with WDM technology are for future study. | + +**Table A.2 – Illustrative system parameters of repeaterless optical fibre submarine cable systems beyond 5 Gbit/s** + +| Systems | 10 G (SDH)
32 × 140/155
[Mbit/s] | | | +|---------------------------------------|-------------------------------------------------|-----------------------------------------------------------------|--| +| Transmission capacity (ch. 64 kbit/s) | 120'960-122'880 | | | +| Information bit rate [Mbit/s] | ~8'960 | | | +| Line bit rate [Mbit/s] | ~9'953 | | | +| Line code | Scrambled NRZ
(Note 2) | | | +| Maximum system length [km] (Note 1) | >70 | | | +| Water depth [m] | Down to ~4'000 | | | +| Fibre type | ITU-T G.652; ITU-T G.653; ITU-T G.654 | | | +| Operating wavelength [nm] | ~1'550 | | | +| System design life [year] | 25 | | | +| Reliability (Note 3) | <1 repair in 25 years | | | +| Error performance | ITU-T G.821 | ITU-T G.826 | | +| Jitter | ITU-T G.823 | ITU-T G.825 (optical interfaces)
FFS (electrical interfaces) | | + +| | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NOTE 1 – The maximum system length is only indicative. The length can be increased considerably by using both non-standard PDH and SDH systems or optical booster amplifiers and/or optical pre-amplifiers. Remote optically pumped amplifiers can also be used for increasing the length (see Figure A.2). | +| NOTE 2 – In SDH systems, scrambled NRZ code is used. | +| NOTE 3 – Refer to clause 6.3. | +| NOTE 4 – It will be possible to consider WDM technology to increase the transmission capacity and network flexibility of the systems. System parameters of repeaterless optical submarine cable systems with WDM technology are for future study. | + +**Table A.3 – Illustrative system parameters of repeaterless optical fibre submarine cable systems with wavelength division multiplexing technology** + +| Systems | 100 G | | | | | | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------|--|--|--|--|--| +| Transmission capacity | $N \times 100\text{Gbit/s}$ | | | | | | +| Information bit rate [Gbit/s] | [Note 1] | | | | | | +| Line bit rate [Gbit/s] | [Note 2] | | | | | | +| Line code | PDM-QPSK
DC-PDM-BPSK
PDM-DQPSK
DC-PDM-DBPSK | | | | | | +| Maximum system length [km]
(Note 3) | >70 | | | | | | +| Water depth [m] | Down to ~4000 | | | | | | +| Fibre type | ITU-T G.652; ITU-T G.653; ITU-T G.654 | | | | | | +| Operating wavelength [nm] | ~1550 | | | | | | +| System design life [year] | 25 | | | | | | +| Reliability (Note 4) | <1 failure in 25 years | | | | | | +| Error performance | ITU-T G.8201 | | | | | | +| Jitter | FFS | | | | | | +| NOTE 1 – The information bit rate is according to the client signal transported by the one wavelength of the system, including CBR, Ethernet, SDH and OTN services. | | | | | | | +| NOTE 2 – Line bit rate depends on the FEC redundancy added by the system. | | | | | | | +| NOTE 3 – The maximum system length is only indicative. The length can be increased considerably by using OTN systems (high gain FEC and digital signal processing function) or optical booster amplifiers and/or optical pre-amplifiers. Distributed Raman amplifiers and/or remote optically pumped amplifiers can also be used for increasing the length (see Figure A.2). | | | | | | | +| NOTE 4 – Refer to clause 6.3. | | | | | | | + +## A.2 System configuration + +### A.2.1 Constituents of repeaterless optical fibre submarine cable systems + +The purpose of a repeaterless optical fibre submarine cable system is to establish transmission links between two or more terminal stations located in a restricted geographical area. + +When only two terminal stations are connected by the cable system, then it may be termed an "optical fibre submarine cable link". In the other case it may be termed an "optical fibre submarine cable network". + +Figure A.1 shows the basic concept of repeaterless optical fibre submarine cable system and boundaries. Optical submarine branching units could be included, depending on each system requirement. + +![Diagram of a repeaterless optical fibre submarine cable system. The system is divided into three main sections: Land portion (1004) at both ends and a Submarine portion (1005) in the middle. On the left land portion, a system interface 'A' connects to a TTE (1010) with optical source output 'O'. This is connected via an optical section (2004) to a CTE (1014) with transmit terminal optical interface 'S'. The submarine portion includes an elementary cable section (1029), a branching unit (1022), a remote optically pumped amplifier (1041), and a cable jointing box (5013) marked with an 'X'. The optical path continues through another optical section (2004) to another CTE (1014) with receive terminal optical interface 'R', which then connects to a TTE (1010) with optical detector input 'I'. This TTE connects to system interface 'A' on the right land portion. Supervisory sections (2007) are shown connecting maintenance controllers (1012) to the CTEs. A legend defines the line types: double line for optical fibre submarine cable, single line for optical fibre land cable, double line with a cross for optical fibre station cable, and single line for electrical. Optical interfaces are marked with open circles, and system interfaces with solid black circles.](7133ccf78043568ca62ecbcd43628a4a_img.jpg) + +NOTE 1 – A denotes system interface (2008). + NOTE 2 – B denotes landing points or beach joints (1006). + NOTE 3 – A-B represents land portion (1004). + NOTE 4 – B-B represents submarine portion (1005). + NOTE 5 – X denotes cable jointing box (5013). + NOTE 6 – Numbers in brackets relate to [ITU-T G.972]. + NOTE 7 – O denotes optical source output (2005). + NOTE 8 – I denotes optical detector input (2006). + NOTE 9 – S denotes transmit terminal optical interface (2010). + NOTE 10 – R denotes receive terminal optical interface (2011). + +Diagram of a repeaterless optical fibre submarine cable system. The system is divided into three main sections: Land portion (1004) at both ends and a Submarine portion (1005) in the middle. On the left land portion, a system interface 'A' connects to a TTE (1010) with optical source output 'O'. This is connected via an optical section (2004) to a CTE (1014) with transmit terminal optical interface 'S'. The submarine portion includes an elementary cable section (1029), a branching unit (1022), a remote optically pumped amplifier (1041), and a cable jointing box (5013) marked with an 'X'. The optical path continues through another optical section (2004) to another CTE (1014) with receive terminal optical interface 'R', which then connects to a TTE (1010) with optical detector input 'I'. This TTE connects to system interface 'A' on the right land portion. Supervisory sections (2007) are shown connecting maintenance controllers (1012) to the CTEs. A legend defines the line types: double line for optical fibre submarine cable, single line for optical fibre land cable, double line with a cross for optical fibre station cable, and single line for electrical. Optical interfaces are marked with open circles, and system interfaces with solid black circles. + +G.973(10)\_FA.1 + +**Figure A.1 – Example of repeaterless optical fibre submarine cable system** + +In Figure A.1, "A" denotes the system interface at the terminal station (where the system can be interfaced to terrestrial digital links or to other submarine cable systems), and "B" denotes beach joints or landing points. Letters in brackets in the following paragraphs refer to Figure A.1. + +A repeaterless optical fibre submarine cable system consists of: + +- a land portion, between the system interface in the terminal station (A) and the beach joint or landing point (B), which includes the optical fibre land cable, land joints, and the system terminal equipment, eventually in combination with OFAs (power amplifier and/or pre-amplifier) and/or in combination with the appropriate electronic components necessary to perform the remote pumping for the distributed amplifiers; +- a submarine portion on the seabed, between the beach joints or landing points (B), which includes the optical fibre submarine cable and, where necessary, submarine equipment, i.e., branching unit(s) and cable jointing box(es), and eventually a doped fibre to be used as ROPA, which could be implemented either in a special box laid on the seabed or incorporated in the cable. + +The cable contains one or more optical fibre pairs (an optical fibre pair is used to establish transmission in both directions). + +The optical fibre submarine cable is protected where appropriate: there are several different types of cable characterized by their mechanical structure, such as lightweight cable, lightweight protected cable, lightwire armoured cable, single armoured cable, double armoured cable and rock armoured cable. + +The optical fibre land cable also requires protection. + +### **A.2.2 Transmission configuration** + +The transmission configuration characterizes the flow of information between the terminal stations across the optical fibre submarine cable system. + +An optical fibre cable section may contain a number of optical fibre pairs, and an optical fibre pair may support a number of digital line sections. The number of a digital line sections carried by an optical fibre cable section is given by the product of these two numbers. + +A passive optical submarine branching unit (BU) is inserted into the submarine portion of an optical fibre submarine cable network, where it is necessary to interconnect more than two cable sections. + +### **A.2.3 Supervision and remote maintenance of the system** + +Supervisory and remote maintenance equipment located in the terminal, in association with the BU supervisory unit, normally provides for fault localization. + +The supervisory facilities commonly include one or more of the following: + +- provision, on an in-service basis, of sufficient information to enable preventive maintenance; +- indication of approaching failure of the in-service equipment, so that preventive action may be undertaken or planned (e.g., by means of error correction coding in accordance with [ITU-T G.975]); +- the means to locate hard faults and intermittent faults of duration and frequency that cause the system to fail to meet the performance requirement. + +Other means, such as optical reflectometry and electrical measurement using equipment installed in the terminal stations or on board the cable ship may permit increased accuracy of fault localization. + +Supervision of the system may be facilitated by computerized equipment, located at one or both ends. + +When using OFAs, for the control of their critical parameters, it is preferable that the OFAs' maintenance channels are connected to the existing maintenance circuitry of the TTE. In fact, in the amplified system configurations (see Figure A.2) it is not necessary to adopt a dedicated service channel independent from the SDH and PDH frame in order to transfer and manage the power amplifiers and pre-amplifiers alarms. + +For the ROPA in which the submersible plant is wholly passive and where the total active part (electro-optic components as well as pump(s) lasers) is located in the transmit or receive side of the TTE, no specific maintenance policy different from the one adopted for the TTE should be considered. + +![Figure A.2 – Possible system configurations. The diagram shows six different optical system configurations between two Optical line terminals (Tx/Rx). 1. Without optical amplifier: Direct connection between Tx and Rx. 2. With optical power amplifier: Tx connects to an amplifier (S to S'), which then connects to Rx. 3. With optical power amplifier and pre-amplifier: Tx connects to an amplifier (S to S'), which connects to another amplifier (R' to R), which then connects to Rx. 4. With optical power pre-amplifier: Tx connects to an amplifier (R' to R), which then connects to Rx. 5. With remotely pumped amplifier: Tx connects to active fibres with remote pump sources (indicated by triangles), which then connect to Rx. 6. With distributed Raman amplifier: Tx connects to active fibres with Raman pump sources (indicated by triangles), which then connect to Rx. Labels include S, R, S', R', and 'Active fibres'. A legend indicates that a triangle pointing right represents a 'Remote pump source' and a triangle pointing left represents a 'Raman pump source'. The diagram is labeled G.973(16)_FA.2.](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg) + +Figure A.2 – Possible system configurations. The diagram shows six different optical system configurations between two Optical line terminals (Tx/Rx). 1. Without optical amplifier: Direct connection between Tx and Rx. 2. With optical power amplifier: Tx connects to an amplifier (S to S'), which then connects to Rx. 3. With optical power amplifier and pre-amplifier: Tx connects to an amplifier (S to S'), which connects to another amplifier (R' to R), which then connects to Rx. 4. With optical power pre-amplifier: Tx connects to an amplifier (R' to R), which then connects to Rx. 5. With remotely pumped amplifier: Tx connects to active fibres with remote pump sources (indicated by triangles), which then connect to Rx. 6. With distributed Raman amplifier: Tx connects to active fibres with Raman pump sources (indicated by triangles), which then connect to Rx. Labels include S, R, S', R', and 'Active fibres'. A legend indicates that a triangle pointing right represents a 'Remote pump source' and a triangle pointing left represents a 'Raman pump source'. The diagram is labeled G.973(16)\_FA.2. + +**Figure A.2 – Possible system configurations** + +### A.2.4 System integration + +A submarine optical fibre cable link or network may be constructed using two or more submarine optical fibre cable systems (i.e., sets of equipment, cable, terminal equipment, BU, etc.) designed independently by different suppliers. + +To integrate the submarine optical fibre network, it is necessary to ensure the compatibility of these designs. This is the purpose of the integration specifications. + +## A.3 Characteristics of the line signal + +### A.3.1 Structure of the line signal + +The line frame and the line bit rate result from the multiplexing and coding operations performed by the TTE, taking into account the inclusion of the service and supervisory channels. + +For PDH systems, the line code is chosen so as to suit the characteristics of the submarine portion. It can be used for such purposes as adapting the frequency spectrum on the optical line signal at the optical interface, and monitoring the line bit error rate at the receive terminal equipment. Violations of the line code may be used for supervisory purposes (system monitoring and/or transmission of supervisory information). + +For SDH systems, the line code and its violation should comply with the relevant Recommendations. + +For OTN systems, the line code and its violation should comply with the relevant Recommendations. + +For PDH, SDH and OTN systems, the line code could be utilized in combination with an error correction coding (e.g., in accordance with [ITU-T G.975] or [ITU-T G.975.1] relating to forward error correction for submarine systems) in order to improve the system performances. + +### **A.3.2 Line error ratio** + +Numerical values of the line error ratio are expressed in the form $n \times 10^{-p}$ , where $p$ is an integer. + +For PDH systems, generally the supervisory equipment detects violations of the line code. The apparent line error ratio is directly calculated from the result of this observation. A more accurate value, the actual line error ratio, can be obtained by eliminating deliberate violations of the line code from the calculation. Violations of the line code may be used for supervisory or monitoring purposes. + +For SDH systems, the line error ratio is evaluated on the received line signal based on parity violations on the bytes B2 [Multiplex Section Overhead (MSOH)] of the SDH frame. + +For OTN systems, the line error ratio is evaluated on the received line signal. + +## **A.4 System operation** + +### **A.4.1 Terminal-to-terminal communication** + +Generally, at least two service channels are established between two terminal stations: one through the optical fibre submarine cable system for the purpose of operating and maintaining the system, the other through external means for the purpose of maintaining the communication between two terminals stations in case of system fault. + +In particular, a service channel is normally provided to allow transmission of terminal-to-terminal messages between the supervisory equipment of corresponding terminal stations to provide information on the status of the system and of the digital line sections, and on the ongoing supervisory activity, so as to help in overall system monitoring and in supervision. + +One order wire channel may be established between terminal stations exchanging traffic for communication between the staff of the terminal stations. + +## **A.5 Passive branching unit characteristics** + +### **A.5.1 General** + +The optical submarine passive branching units are: + +- capable of being operated in accordance with the system performance recommendations during the system design life and at the sea depth environment conditions (temperature, pressure, etc.); +- designed to be capable of being handled, i.e., laid, recovered and relayed, without impairment of the performance of the cable, cable jointing boxes, branching units and couplers, provided that handling specifications are respected; +- designed to be transported and stored under specified temperature conditions without affecting the system design life, provided that storage and transport specifications are respected; +- capable of being operated on board a cable ship during laying and repair operations without affecting the system design life. + +The size of the optical submarine branching units is such that it can be handled by appropriate cable-ship equipment. + +### **A.5.2 BU constituents** + +The main BU constituents are: + +- the BU housing: +the mechanical piece part. The housing is designed to provide resistance to the sea depth pressure, watertightness, high mechanical strength and optical connection to the cable sections on each side of the BU. + +# Annex B + +## Repeaterless optical fibre submarine cable systems using ROPA: optical power budget between optical reference points S and R and line monitoring + +(This annex forms an integral part of this Recommendation.) + +## B.1 Remote optically pumped amplifiers (ROPA) + +The use of ROPA is a technique very likely to provide great benefit to repeaterless submarine systems. + +A ROPA consists of a section of doped fibre which is activated by a pump beam sent from the terminal station. There is no electrical power feeding of the remote optical amplifier. + +This technique can be employed at either the transmit or receive side of a link (all the electro-optic components, mainly pump lasers, will be placed in the terminal stations), although experience has shown that it is more efficient at the receive side. + +- i) The doped fibre in combination with an optical isolator make up a wholly passive device which could be implemented as shown in Figure B.1, either in a special box laid on the seabed or incorporated in the cable. + +The optimum placement of the doped fibre along the link is fixed by a compromise between the following parameters: + +- noise factor of the doped fibre; +- remotely pumped optical amplifier gain; +- available pump laser(s) optical power; +- optical line fibre loss; +- repair cable margin of the fibre between the doped fibre and the transmit or receive terminal station. + +Experience has shown that a good compromise is to have the doped fibre located some tens of kilometres from the receive side. This allows for an allocation of about 1 dB of repair cable margin for the entire system design life. Moreover, the repair cable margin can be increased following the increase of the pump laser optical power without causing any consequence to the submersible part of the system. + +- ii) Distributed Raman amplification + +Under study. + +## B.2 Optical power budget for systems using ROPA + +In order to increase the optical section length, it is necessary to optimize the location of the doped fibre along the link. + +The definition of the optical power budget as given in clause 6.2.1 cannot be applied in this case since there is an amplification of the optical signal along the link. + +The optical power budget is therefore no longer equal to the optical power difference between the two ends of the link, but it is equal to the allowable loss between the two ends of the links (i.e., between the optical reference points S and R). + +With reference to the example given in Figure B.1, the link gain is expressed in the following way: + +- Link gain = Budget (with ROPA) – Budget (without ROPA) +- Link gain = $(A_1 + A_2)$ (with ROPA) – $A_1$ (without ROPA) + +where $A_1$ and $A_2$ are the attenuations of the fibre before and after the doped fibre, respectively. + +The above formula shows that the evolution of the budget gain is a function of the pump laser optical power and of the fibre attenuation between the doped fibre amplifier and the receive station ( $A_2$ ). (See Figure B.1.) + +![Figure B.1: Example of system configuration with ROPA from the receiver end. The diagram shows a transmitter (Tx) connected to a line fibre with attenuation A1. This is followed by an Erbium-doped fibre, which is then followed by another line fibre with attenuation A2. The signal then enters a 'Terminal station' box. Inside the box, the signal goes through a Multiplexer, then an Optical filter (which has a peak response curve), and finally to a receiver (Rx). A Pump laser is also connected to the Multiplexer.](00504fc688ebcf131ccbeff94dfc9939_img.jpg) + +G.973(16)\_FB.1 + +Figure B.1: Example of system configuration with ROPA from the receiver end. The diagram shows a transmitter (Tx) connected to a line fibre with attenuation A1. This is followed by an Erbium-doped fibre, which is then followed by another line fibre with attenuation A2. The signal then enters a 'Terminal station' box. Inside the box, the signal goes through a Multiplexer, then an Optical filter (which has a peak response curve), and finally to a receiver (Rx). A Pump laser is also connected to the Multiplexer. + +**Figure B.1 – Example of system configuration with ROPA from the receiver end** + +## B.3 Line monitoring for pumping portion + +The performance of the repeaterless system with a distributed Raman amplifier and ROPA is singularly dependent on pump power, fibre losses in the pumped fibre section and fault conditions. A line monitoring system of the remote pumping portion is required to monitor the status and performance from the land station. This line monitoring system must be able to operate when the link is in-service and/or out-of-service without disturbing the system performance. + +Figure B.2 shows the basic configuration of line monitoring in the repeaterless optical fibre submarine cable system. Optical time domain reflectometer (OTDR) is one of the candidate systems and is used primarily for the characterization and the fault localization of optical fibres, and can be achieved as a monitoring system of optical amplifier gain characteristics. + +Two valuable characteristics are obtained in accordance with line monitoring: + +- distributed Raman amplification gain (optical amplifier gain distribution); +- optical amplification gain of ROPA. + +NOTE 1 – No optical isolator in ROPA is required to determine the optical amplifier gain. For applications of ROPA with optical isolators, the determination of the amplifier gain cannot be performed. + +NOTE 2 – The line monitoring capability of the distributed Raman amplification gain will not be affected by optical isolators in ROPA. + +OTDR can be classified into two detection categories. These two categories are direct-detection and coherent-detection techniques. Coherent OTDR (COTDR) is more advantageous than direct detection type for line monitoring, because it can achieve high detection sensitivity and excellent selectivity for a weak backscatter signal in the presence of the accumulated spontaneous emission noise. + +For the probe light requirement for OTDR, the probe light having a weak signal power, probe shape and wavelength that will not affect the transmission performance is required. In particular, the launch of a high-power probe light into the amplifier systems raises degradations on the transmission performance. (See Figure B.2.) + +![Diagram of line monitoring using OTDR](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +The diagram illustrates a line monitoring setup. On the left, an input labeled S (S') enters a box labeled 'Multiplexer'. Below this multiplexer is a box labeled 'OTDR', connected by a vertical double-headed arrow. A horizontal arrow points from the right side of the left 'Multiplexer' box to the left side of a second 'Multiplexer' box on the right, with the label 'Optical section' above this arrow. Below the right 'Multiplexer' box is another box labeled 'OTDR', also connected by a vertical double-headed arrow. An arrow points from the right side of the right 'Multiplexer' box to an output labeled R (R'). A small label 'G.973(16)\_FB.2' is located below the right 'OTDR' box. + +Diagram of line monitoring using OTDR + +**Figure B.2 – Example of line monitoring using OTDR** + +# **Bibliography** + +- [b-ITU-T G.Sup39] ITU-T G-series Supplement 39 (2016), *Optical system design and engineering considerations.* +- [b-ITU-T G.Sup41] ITU-T G-series Supplement 41 (2010), *Design guidelines for optical fibre submarine cable systems.* + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.973.2-201104-I_PDF-E/raw.md b/marked/G/T-REC-G.973.2-201104-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..39f03633ac463d8b12eb56685003ba8fa66ef27b --- /dev/null +++ b/marked/G/T-REC-G.973.2-201104-I_PDF-E/raw.md @@ -0,0 +1,489 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.973.2** + +(04/2011) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical fibre +submarine cable systems + +--- + +**Multichannel DWDM applications with single +channel optical interfaces for repeaterless +optical fibre submarine cable systems** + +Recommendation ITU-T G.973.2 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.973.2 + +# Multichannel DWDM applications with single channel optical interfaces for repeaterless optical fibre submarine cable systems + +# Summary + +Recommendation ITU-T G.973.2 provides optical interface specifications towards the realization of transversely compatible dense wavelength division multiplexing (DWDM) systems intended for repeaterless submarine applications. + +This Recommendation defines parameters for the single-channel optical interface of physical point-to-point DWDM applications on single-mode optical fibres through the use of the "black-link" approach. + +Applications containing DWDM optical amplifiers are not defined in this Recommendation. + +This Recommendation describes DWDM systems that include the following features: + +- Channel frequency spacing: 100 GHz and below (defined in ITU-T G.694.1). +- Bit-rate of signal channel: up to 10 Gbit/s. + +## History + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.973.2 | 2011-04-13 | 15 | + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2012 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 4 Abbreviations..... | 2 | +| 5 Convention..... | 3 | +| 6 Applications..... | 3 | +| 7 Reference configuration..... | 4 | +| 7.1 Unidirectional applications..... | 4 | +| 7.2 Bidirectional applications ..... | 4 | +| 8 Transverse compatibility ..... | 5 | +| 9 Parameter definitions ..... | 5 | +| 9.1 General information..... | 6 | +| 9.2 Interface at point SS ..... | 7 | +| 9.3 Optical path parameters (single span) from S S to RS..... | 7 | +| 9.4 Interface at point RS..... | 8 | +| 10 Reliability of submarine system ..... | 8 | +| 11 Characteristics and performance of submarines cables ..... | 9 | +| 12 Optical safety considerations..... | 9 | +| Bibliography..... | 10 | + + + +## Recommendation ITU-T G.973.2 + +## Multichannel DWDM applications with single channel optical interfaces for repeaterless optical fibre submarine cable systems + +# 1 Scope + +The purpose of this Recommendation is to provide optical interface specifications towards the realization of transversely compatible dense wavelength division multiplexing (DWDM) systems intended for repeaterless submarine applications. + +This Recommendation defines parameters for single-channel optical interface of physical point-to-point DWDM applications on single-mode optical fibres through the use of the "black-link" approach. + +*Applications containing DWDM optical amplifiers are not defined in this Recommendation.* + +This Recommendation describes DWDM systems that include the following features: + +- Channel frequency spacing: 100 GHz and below (defined in [ITU-T G.694.1]). +- Bit-rate of signal channel: up to 10 Gbit/s. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.652] Recommendation ITU-T G.652 (2009), *Characteristics of a single-mode optical fibre cable.* +- [ITU-T G.653] Recommendation ITU-T G.653 (2010), *Characteristics of a dispersion-shifted single-mode optical fibre cable.* +- [ITU-T G.654] Recommendation ITU-T G.654 (2010), *Characteristics of a cut-off shifted single-mode optical fibre and cable.* +- [ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable.* +- [ITU-T G.656] Recommendation ITU-T G.656 (2010), *Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport.* +- [ITU-T G.661] Recommendation ITU-T G.661 (2007), *Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems.* +- [ITU-T G.671] Recommendation ITU-T G.671 (2009), *Transmission characteristics of optical components and subsystems.* +- [ITU-T G.691] Recommendation ITU-T G.691 (2006), *Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers.* +- [ITU-T G.692] Recommendation ITU-T G.692 (1998), *Optical interfaces for multichannel systems with optical amplifiers.* + +- [ITU-T G.694.1] Recommendation ITU-T G.694.1 (2002), *Spectral grids for WDM applications: DWDM frequency grid.* +- [ITU-T G.694.2] Recommendation ITU-T G.694.2 (2003), *Spectral grids for WDM applications: CWDM wavelength grid.* +- [ITU-T G.698.1] Recommendation ITU-T G.698.1 (2009), *Multichannel DWDM applications with single-channel optical interfaces.* +- [ITU-T G.957] Recommendation ITU-T G.957 (2006), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy.* +- [ITU-T G.959.1] Recommendation ITU-T G.959.1 (2009), *Optical transport network physical layer interfaces.* +- [ITU-T G.972] Recommendation ITU-T G.972 (2008), *Definition of terms relevant to optical fibre submarine cable systems.* +- [ITU-T G.973] Recommendation ITU-T G.973 (2010), *Characteristics of repeaterless optical fibre submarine cable systems.* +- [ITU-T G.978] Recommendation ITU-T G.978 (2010), *Characteristics of optical fibre submarine cables.* + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **dense wavelength division multiplexing (DWDM)**: [ITU-T G.972]. +- 3.1.2 **multichannel receive main path interface reference point (MPI-RM)**: [ITU-T G.959.1]. +- 3.1.3 **multichannel source main path interface reference point (MPI-SM)**: [ITU-T G.959.1]. +- 3.1.4 **optical tributary signal**: [ITU-T G.959.1]. +- 3.1.5 **optical tributary signal class NRZ 2.5G**: [ITU-T G.959.1]. +- 3.1.6 **optical tributary signal class NRZ 10G**: [ITU-T G.959.1]. +- 3.1.7 **polarization mode dispersion (PMD)**: [ITU-T G.650.2]. +- 3.1.8 **transverse compatibility**: [ITU-T G.957]. +- 3.1.9 **wavelength division multiplexing (WDM)**: [ITU-T G.972]. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|-------------------------------------------| +| ASE | Amplified Spontaneous Emission | +| BER | Bit Error Ratio | +| CSF | Cut-off Shifted single-mode Fibre | +| CWDM | Coarse Wavelength Division Multiplexing | +| DCF | Dispersion Compensating single-mode Fibre | +| DGD | Differential Group Delay | +| DSF | Dispersion Shifted single-mode Fibre | + +| | | +|----------------|-----------------------------------------------------------------------------| +| DWDM | Dense Wavelength Division Multiplexing | +| EX | EXtinction ratio | +| FEC | Forward Error Correction | +| IrDI | Inter-Domain Interface | +| LEF | Large Effective area single-mode Fibre | +| MPI | Main Path Interface | +| NDF | Negative Dispersion single-mode Fibre | +| NE | Network Element | +| NRZ | Non-Return to Zero | +| NZDSF | Non-Zero Dispersion Shifted single-mode Fibre | +| OA | Optical Amplifier | +| OD | Optical Demultiplexer | +| OM | Optical Multiplexer | +| OTN | Optical Transport Network | +| PMD | Polarization Mode Dispersion | +| R s | Single-channel reference point at the DWDM network element tributary output | +| RZ | Return to Zero | +| SDH | Synchronous Digital Hierarchy | +| S s | Single-channel reference point at the DWDM network element tributary input | +| WDM | Wavelength Division Multiplexing | +| WNZDF | Wideband Non-Zero Dispersion single-mode Fibre | + +# 5 Convention + +This clause is intentionally left blank. + +# 6 Applications + +This Recommendation provides the physical layer parameters for the single-channel interfaces of dense wavelength division multiplexing (DWDM) multi-channels optical repeaterless submarine systems. These DWDM systems with single-channel interfaces are intended to be used in point to point applications. + +The specification method in this Recommendation uses a "black-link" approach, which means that optical interface parameters for only (single-channel) optical tributary signals are specified. This approach enables transverse compatibility at the single-channel point using a direct wavelength-multiplexing configuration. However, it does not enable transverse compatibility at the multichannel points. In this approach, the optical multiplexer (OM) and optical demultiplexer (OD) are treated as a single set of optical devices. + +This Recommendation only considers DWDM applications where the black-link does not contain optical amplifiers. + +# 7 Reference configuration + +## 7.1 Unidirectional applications + +Figure 7-1 shows a set of reference points, for the "black-link" approach, for single-channel connection ( $S_S$ and $R_S$ ) between transmitters (Tx) and receivers (Rx). Here the DWDM link includes an OM and an OD, which are used as a pair with the opposing element. + +The fibre between point $S_S$ or $R_S$ and the DWDM link is considered to be part of the black-link in cases where the transmitter or receiver is some distance far from the OM or OD. + +![Figure 7-1: 'black-link' approach for unidirectional applications. The diagram shows a 'DWDM link' containing a 'Pair of DWDM network elements' consisting of an OM (Optical Multiplexer) and an OD (Optical Demultiplexer). On the left, multiple transmitters (Tx) labeled λ1, λ2, ..., λN are connected to the OM via single-channel reference points Ss. On the right, the OD is connected to multiple receivers (Rx) labeled λ1, λ2, ..., λN via single-channel reference points Rs. Inside the DWDM link, between the OM and OD, are two aggregate reference points: MPI-S (MPI-S for signals going right) and MPI-R (MPI-R for signals going left). The diagram is labeled G.973.2(11)_F7-1.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg) + +Figure 7-1: 'black-link' approach for unidirectional applications. The diagram shows a 'DWDM link' containing a 'Pair of DWDM network elements' consisting of an OM (Optical Multiplexer) and an OD (Optical Demultiplexer). On the left, multiple transmitters (Tx) labeled λ1, λ2, ..., λN are connected to the OM via single-channel reference points Ss. On the right, the OD is connected to multiple receivers (Rx) labeled λ1, λ2, ..., λN via single-channel reference points Rs. Inside the DWDM link, between the OM and OD, are two aggregate reference points: MPI-S (MPI-S for signals going right) and MPI-R (MPI-R for signals going left). The diagram is labeled G.973.2(11)\_F7-1. + +Figure 7-1 – "black-link" approach for unidirectional applications + +This reference model does not include any optical amplifiers in the DWDM system. The reference points in Figure 7-1 are defined as follows: + +- $S_S$ is a single-channel reference point at the DWDM link tributary input; +- $R_S$ is a single-channel reference point at the DWDM link tributary output; +- MPI-S is a link reference point at the DWDM network element aggregate output; +- MPI-R is a link reference point at the DWDM network element aggregate input. + +Note that MPI-S and MPI-R are only defined to provide information for the fibre link and not to provide signal characteristics at these points. + +## 7.2 Bidirectional applications + +Figure 7-2 shows a set of reference points, for the single-fibre bidirectional "black-link" approach, for single-channel connection ( $S_S$ and $R_S$ ) between transmitters (Tx) and receivers (Rx). Here the DWDM network elements include an OM/OD, which is used as a pair with the opposing element. + +![Figure 7-2: 'black-link' approach for bidirectional applications. The diagram shows a 'DWDM link' containing a 'Pair of DWDM network elements' consisting of an OM/OD (Optical Multiplexer/Demultiplexer) and an OD/OM (Optical Demultiplexer/Multiplexer). On the left, transmitters (Tx) labeled λ1, λ2, ..., λN-1, λN are connected to the OM/OD via single-channel reference points Ss, and receivers (Rx) labeled λN-1, ..., λ2, λ1 are connected via single-channel reference points Rs. On the right, the OD/OM is connected to transmitters (Tx) labeled λN-1, ..., λ2, λ1 via single-channel reference points Ss, and receivers (Rx) labeled λ1, λ2, ..., λN via single-channel reference points Rs. Inside the DWDM link, between the OM/OD and OD/OM, are four aggregate reference points: MPI-S for signals going right, MPI-R for signals going right, MPI-R for signals going left, and MPI-S for signals going left. The diagram is labeled G.973.2(11)_F7-2.](b10763be31553f31cbb795653b731a43_img.jpg) + +Figure 7-2: 'black-link' approach for bidirectional applications. The diagram shows a 'DWDM link' containing a 'Pair of DWDM network elements' consisting of an OM/OD (Optical Multiplexer/Demultiplexer) and an OD/OM (Optical Demultiplexer/Multiplexer). On the left, transmitters (Tx) labeled λ1, λ2, ..., λN-1, λN are connected to the OM/OD via single-channel reference points Ss, and receivers (Rx) labeled λN-1, ..., λ2, λ1 are connected via single-channel reference points Rs. On the right, the OD/OM is connected to transmitters (Tx) labeled λN-1, ..., λ2, λ1 via single-channel reference points Ss, and receivers (Rx) labeled λ1, λ2, ..., λN via single-channel reference points Rs. Inside the DWDM link, between the OM/OD and OD/OM, are four aggregate reference points: MPI-S for signals going right, MPI-R for signals going right, MPI-R for signals going left, and MPI-S for signals going left. The diagram is labeled G.973.2(11)\_F7-2. + +Figure 7-2 – "black-link" approach for bidirectional applications + +The reference points in Figure 7-2 are as defined in clause 7.1. + +# 8 Transverse compatibility + +[b-ITU-T G.Sup41] describes several transverse compatibility configurations for point to point submarine transmission systems. This Recommendation deals with a single-span black-link transverse compatibility as shown in Figure 8-1. + +![Diagram of single-span black-link transverse compatibility. On the left, multiple transceivers (Tx λ1, Tx λ2, ..., Tx λN) from Vendor A1 and Vendor A2 are connected to a central DWDM link via interface points S1, S2, ..., SN. The DWDM link is a grey box containing a pair of DWDM network elements: an Optical Multiplexer (OM) and an Optical Demultiplexer (OD). Inside the link, there are MPI-S and MPI-R interfaces. On the right, the DWDM link connects to multiple receivers (Rx λ1, Rx λ2, ..., Rx λN) from Vendor C1 and Vendor C2 via interface points R1, R2, ..., RN. The diagram is labeled G.973.2(11)_F8-1.](e9314c83043183351ed74908e9bf2f90_img.jpg) + +Diagram of single-span black-link transverse compatibility. On the left, multiple transceivers (Tx λ1, Tx λ2, ..., Tx λN) from Vendor A1 and Vendor A2 are connected to a central DWDM link via interface points S1, S2, ..., SN. The DWDM link is a grey box containing a pair of DWDM network elements: an Optical Multiplexer (OM) and an Optical Demultiplexer (OD). Inside the link, there are MPI-S and MPI-R interfaces. On the right, the DWDM link connects to multiple receivers (Rx λ1, Rx λ2, ..., Rx λN) from Vendor C1 and Vendor C2 via interface points R1, R2, ..., RN. The diagram is labeled G.973.2(11)\_F8-1. + +**Figure 8-1 – Single-span black-link transverse compatibility** + +The vendors of the transceivers at the ends of an optical section may be different from the vendor of the equipment of the DWDM optical submarine link. Most of the transceivers are bidirectional; therefore, Vendor A1 is almost the same Vendor as C1. + +# 9 Parameter definitions + +The parameters in Table 1 are defined at the interface points, and the definitions are provided in the clauses below. + +**Table 1 – Physical layer parameters for DWDM applications using the "black-link" approach** + +| Parameter | Units | Defined in | +|---------------------------------------------------|-------|--------------| +| General information | | | +| Minimum channel spacing | GHz | clause 9.1.1 | +| Bit-rate/line coding of optical tributary signals | – | clause 9.1.2 | +| Maximum bit-error ratio | – | clause 9.1.3 | +| Fibre type | – | clause 9.1.4 | +| Interface at point Ss | | | +| Maximum mean channel output power | dBm | clause 9.2.1 | +| Minimum mean channel output power | dBm | clause 9.2.1 | +| Minimum central frequency | THz | clause 9.2.2 | +| Maximum central frequency | THz | clause 9.2.2 | +| Maximum spectral excursion | GHz | clause 9.2.3 | +| Minimum side mode suppression ratio | dB | clause 9.2.4 | +| Minimum channel extinction ratio | dB | clause 9.2.5 | +| Eye mask | – | clause 9.2.6 | + +**Table 1 – Physical layer parameters for DWDM applications using the "black-link" approach** + +| Parameter | Units | Defined in | +|---------------------------------------------------------------|-------|--------------| +| Optical path from point Ss to Rs | | | +| Maximum attenuation | dB | clause 9.3.1 | +| Minimum attenuation | dB | clause 9.3.1 | +| Maximum differential group delay | ps | clause 9.3.2 | +| Maximum chromatic dispersion | ps/nm | clause 9.3.3 | +| Maximum ripple | dB | clause 9.3.4 | +| Interface at point Rs | | | +| Maximum mean input power | dBm | clause 9.4.1 | +| Receiver sensitivity | dBm | clause 9.4.2 | +| Maximum optical path penalty | dB | clause 9.4.3 | +| Maximum reflectance of receiver | dB | clause 9.4.4 | + +## 9.1 General information + +### 9.1.1 Minimum channel spacing + +Minimum channel spacing is the minimum nominal difference in frequency between two adjacent channels. Channel spacing is defined in [ITU-T G.694.1] for DWDM as well as in [ITU-T G.694.2] for CWDM. A complete classification of WDM systems is in [ITU-T G.671]. + +### 9.1.2 Bit-rate/line coding of optical tributary signals + +Optical tributary signal class NRZ 2.5G applies to continuous digital signals with non-return to zero line coding. Optical tributary signal class NRZ 10G applies to continuous digital signals with non-return to zero line coding. Return to zero (RZ) line coding will be considered in future study. + +### 9.1.3 Maximum bit error ratio + +The maximum bit error ratio (BER) is specified for each optical channel under the extreme case of optical path attenuation and dispersion condition. In the case of use of forward error correction (FEC), the BER is required to be met only after the correction has been applied. + +### 9.1.4 Fibre type + +Several types of optical fibres are used in submarine systems. This Recommendation covers all of the following: + +- single-mode fibres defined in ITU-T Recommendations: + - non-dispersion shifted single-mode fibre (SMF) defined in [ITU-T G.652]; + - dispersion shifted single-mode fibre (DSF) defined in [ITU-T G.653]; + - cut-off shifted single-mode fibre (CSF) defined in [ITU-T G.654]; + - non-zero dispersion-shifted single-mode fibre (NZDSF) defined in [ITU-T G.655]; + - wideband non-zero dispersion single-mode fibre (WNZDF) defined in [ITU-T G.656]; +- positive dispersion single-mode fibre (PDF); +- negative dispersion single-mode fibre (NDF); +- large effective area single-mode fibre (LEF); +- dispersion compensating single-mode fibre (DCF). + +Depending on the system specifications, various combinations of these fibre types may be used to ensure that the system performs correctly. Further information about each type of fibre can be found in [ITU-T G.978]. + +## **9.2 Interface at point S8** + +### **9.2.1 Maximum and minimum mean channel output power** + +Maximum and minimum mean channel output power are defined in [ITU-T G.959.1]. + +### **9.2.2 Minimum and maximum central frequency** + +Central frequencies of wave division multiplexing (WDM) signals are given in [ITU-T G.694.1]. The nominal central frequencies of all channels should be greater than or equal to the minimum central frequency and less than or equal to the maximum central frequency. + +Note that the value of "c" (speed of light in vacuum) that should be used for converting between frequency and wavelength is $2.99792458 \times 10^8$ m/s. + +### **9.2.3 Maximum spectral excursion** + +Maximum spectral excursion for non return to zero (NRZ) coded optical channels is defined in [ITU-T G.959.1] and [ITU-T G.698.1]. + +### **9.2.4 Minimum side mode suppression ratio** + +The side mode suppression ratio of a single longitudinal mode optical source is defined in [ITU-T G.957], [ITU-T G.691] and [ITU-T G.959.1]. + +### **9.2.5 Minimum channel extinction ratio** + +The minimum extinction ratio for NRZ coded WDM channels is defined in [ITU-T G.959.1]. + +### **9.2.6 Eye mask** + +The definition and limits for this parameter are found in [ITU-T G.959.1]. + +## **9.3 Optical path parameters (single span) from S8 to R8** + +### **9.3.1 Minimum and maximum attenuation** + +For any optical channel, it is the minimum (or maximum) reduction in optical power between the input and output ports of the black-link for that channel in the frequency range of the central frequency of the channel $\pm$ the maximum spectral excursion. Minimum and maximum attenuation are defined in [ITU-T G.959.1]. + +### **9.3.2 Maximum differential group delay** + +Differential group delay (DGD) is the time difference between the fractions of a pulse that are transmitted in the two principal states of polarization of an optical signal. For distances greater than several kilometres, and assuming random (strong) polarization mode coupling, DGD in a fibre can be statistically modelled as having a Maxwellian distribution. + +In this Recommendation, the maximum differential group delay is defined to be the value of DGD that the system must tolerate with a maximum sensitivity degradation of 1 dB. + +Due to the statistical nature of polarization mode dispersion (PMD), the relationship between maximum DGD and mean DGD can only be defined probabilistically. The probability of the instantaneous DGD exceeding any given value can be inferred from its Maxwellian statistics. Therefore, if we know the maximum DGD that the system can tolerate, we can derive the equivalent mean DGD by dividing by the ratio of maximum to mean that corresponds to an acceptable probability. Some example ratios are given in Table 2. + +**Table 2 – DGD means and probabilities** + +| Ratio of maximum to mean | Probability of exceeding maximum | +|--------------------------|----------------------------------| +| 3.0 | $4.2 \times 10^{-5}$ | +| 3.5 | $7.7 \times 10^{-7}$ | +| 4.0 | $7.4 \times 10^{-9}$ | + +### 9.3.3 Maximum chromatic dispersion + +This parameter defines the maximum value of uncompensated chromatic dispersion of the optical path that the system shall be able to tolerate. This is considered a worst-case uncompensated dispersion value. Maximum chromatic dispersion is defined in [ITU-T G.959.1]. + +### 9.3.4 Maximum ripple + +The ripple (of a DWDM device) is defined in [ITU-T G.671] and [ITU-T G.698.1]. In this Recommendation, it is applied to the entire black-link from reference point $R_S$ to the corresponding $R_S$ . + +## 9.4 Interface at point $R_S$ + +### 9.4.1 Maximum mean input power + +The maximum acceptable value of the average received power at point $R_S$ to achieve the specified maximum BER. + +### 9.4.2 Receiver sensitivity + +Receiver sensitivities for synchronous digital hierarchy (SDH) single channel systems up to 10 Gbit/s are defined in [ITU-T G.957] and [ITU-T G.691]. Sensitivities for SDH and optical transport network inter-domain interface (OTN IrDI) receivers are defined in [ITU-T G.959.1]. + +Receiver sensitivities are defined as end-of-life, worst-case values taking into account ageing and temperature margins as well as worst-case eye mask and extinction ratio penalties resulting from transmitter imperfections given by the transmitter specification of the particular interface. Receiver sensitivity is defined as the minimum value of average received power at point $R_S$ to achieve a $10^{-12}$ BER. + +Penalties related to path effects, however, are specified separately from the basic sensitivity value. + +### 9.4.3 Maximum optical path penalty + +The path penalty is the apparent reduction of receiver sensitivity due to distortion of the signal waveform during its transmission over the path. This parameter is defined in [ITU-T G.959.1]. + +### 9.4.4 Maximum reflectance of receiver + +Reflections from the receiver back into the DWDM link are specified by the maximum permissible reflectance of the receiver measured at reference point $R_S$ . Optical reflectance is defined in [ITU-T G.671]. + +# 10 Reliability of submarine system + +The reliability of submerged equipments of an optical fibre submarine cable system is generally characterized by: + +- The expected number of repairs requiring intervention by a cable ship. The usual requirement for the reliability of a repeaterless system is less than one failure requiring cable ship intervention during the system design life. + +- The system design life over which the optical fibre submarine cable system is designed to be operational in conformance with its performance specification. Usually, the system design life is a period of 25 years starting at the provisional acceptance date of the system, i.e., the date following installation when the system is claimed to be compliant with the performance specifications. + +# **11 Characteristics and performance of submarines cables** + +The recommended characteristics and performance of the submarine cable are given in [ITU-T G.978]. + +# **12 Optical safety considerations** + +Information on optical safety considerations can be found in [b-ITU-T. G.664], [b-IEC 60825-1], [b-IEC 60825-2] and [b-IEC/TR 61292-4]. + +# Bibliography + +- [b-ITU-T G.Sup41] ITU-T G Series Recommendations – Supplement 41 (2010), *Design guidelines for optical fibre submarine cable systems*. +- [b-ITU-T G.664] Recommendation ITU-T G.664 (2006), *Optical safety procedures and requirements for optical transport systems*. +- [b-IEC 60825-1] IEC 60825-1:2007, *Safety of laser products – Part 1: Equipment classification and requirements*. +- [b-IEC 60825-2] IEC 60825-2:2004, *Safety of laser products – Part 2: Safety of optical fibre communication systems (OFCS)*, plus its amendments. +- [b-IEC/TR 61292-4] IEC/TR 61292-4:2010 (Edition 2), *Optical amplifiers – Part 4: Maximum permissible optical power for the damage-free and safe use of optical amplifiers, including Raman amplifiers*. + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.975.1-200402-I_PDF-E/raw.md b/marked/G/T-REC-G.975.1-200402-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..34588d91757a185993da98b8f21598679ab27313 --- /dev/null +++ b/marked/G/T-REC-G.975.1-200402-I_PDF-E/raw.md @@ -0,0 +1,1949 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.975.1** + +(02/2004) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical fibre +submarine cable systems + +--- + +**Forward error correction for high bit-rate DWDM +submarine systems** + +ITU-T Recommendation G.975.1 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE - GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.975.1** + +# **Forward error correction for high bit-rate DWDM submarine systems** + +# **Summary** + +This Recommendation describes the Forward Error Correction (FEC) functions that have higher-correction ability than RS(255,239) code defined in ITU-T Rec. G.975 for the high bit-rate DWDM submarine cable systems. In Appendix I, super FEC schemes, which have higher-correction ability than RS(255,239) code, are also described. The use of this super FEC function in submarine terminal transmission equipments (TTEs) should not be considered as mandatory. + +###### **Source** + +ITU-T Recommendation G.975.1 was approved on 22 February 2004 by ITU-T Study Group 15 (2001-2004) under the ITU-T Recommendation A.8 procedure. + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2005 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +###### Page + +| | | | +|-----|---------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Terms and definitions ..... | 2 | +| 3.1 | Terms defined in other Recommendations..... | 2 | +| 3.2 | Definitions ..... | 2 | +| 4 | Abbreviations..... | 3 | +| 5 | Super FEC features ..... | 3 | +| 5.1 | General principles of super FEC function ..... | 3 | +| 5.2 | Super FEC scheme ..... | 4 | +| 6 | Definition of super FEC function ..... | 4 | +| 6.1 | Definition..... | 4 | +| 6.2 | Super FEC code algorithm ..... | 5 | +| 6.3 | Properties for super FEC code..... | 5 | +| 6.4 | Super FEC frame structure ..... | 5 | +| 7 | Parameters for super FEC..... | 5 | +| 7.1 | Correction ability ..... | 5 | +| 7.2 | Redundancy ratio..... | 7 | +| 7.3 | Latency ..... | 7 | +| 8 | Supervision ..... | 7 | +| 8.1 | Signal quality supervision ..... | 7 | +| 8.2 | Connectivity supervision..... | 7 | +| | Appendix I – Super FEC schemes ..... | 7 | +| I.1 | Overview ..... | 7 | +| I.2 | RS(255,239)/CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) super FEC code ..... | 8 | +| I.3 | Concatenated BCH super FEC codes ..... | 13 | +| I.4 | RS(1023,1007)/BCH(2047,1952) super FEC code ..... | 19 | +| I.5 | Concatenated RS and product code super-FEC scheme..... | 22 | +| I.6 | LDPC super FEC code ..... | 24 | +| I.7 | Two orthogonally concatenated BCH super FEC code..... | 28 | +| I.8 | Reed-Solomon (2720,2550) super FEC code..... | 41 | +| I.9 | Two interleaved extended BCH(1020,988) super FEC code ..... | 45 | + + + +# Forward error correction for high bit-rate DWDM submarine systems + +# 1 Scope + +This Recommendation describes the Forward Error Correction (FEC) functions that have higher-correction ability than RS(255,239) code defined in ITU-T Rec. G.975 in the optical fibre submarine cable systems. This Recommendation also describes the system requirement concerning supervision for the submarine cable systems. The applications being addressed in this Recommendation are both optically amplified repeated systems (ITU-T Rec. G.977) and repeaterless optical systems (ITU-T Rec. G.973). The use of this FEC function in submarine terminal transmission equipments (TTEs) should not be considered as mandatory. + +It is not the intention of this Recommendation to pursue the transverse compatibility of the system. Therefore, the selection of the FEC frame structures described in this Recommendation is a matter of joint engineering. + +The transmission signal under consideration could be STM-16, STM-64, STM-256, ODU1, ODU2, and ODU3, because submarine systems could be considered as one of the IaDI applications defined in ITU-T Rec. G.872. This does not mean that the bit rate is restricted within the above-mentioned signals. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- ITU-T Recommendation G.691 (2003), *Optical interfaces for single-channel STM-64 and other SDH systems with optical amplifiers*. +- ITU-T Recommendation G.693 (2003), *Optical interfaces for intra-office systems*. +- ITU-T Recommendation G.707/Y.1322 (2003), *Network node interface for the synchronous digital hierarchy (SDH)*. +- ITU-T Recommendation G.709/Y.1331 (2003), *Interfaces for the Optical Transport Network (OTN)*. +- ITU-T Recommendation G.798 (2002), *Characteristics of optical transport network hierarchy equipment functional blocks*. +- ITU-T Recommendation G.805 (2000), *Generic functional architecture of transport networks*. +- ITU-T Recommendation G.872 (2001), *Architecture of optical transport networks*. +- ITU-T Recommendation G.957 (1999), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy*. +- ITU-T Recommendation G.959.1 (2003), *Optical transport network physical layer interfaces*. + +- ITU-T Recommendation G.972 (2000), *Definition of terms relevant to optical fibre submarine cable systems*. +- ITU-T Recommendation G.973 (2003), *Characteristics of repeaterless optical fibre submarine cable systems*. +- ITU-T Recommendation G.975 (2000), *Forward error correction for submarine systems*. +- ITU-T Recommendation G.977 (2000), *Characteristics of optically amplified optical fibre submarine cable systems*. +- IEEE Standard 802.3-2002, *Information Technology – Telecommunication and Information Exchange between Systems – LAN/MAN – Specific Requirements – Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications*. + +# 3 Terms and definitions + +## 3.1 Terms defined in other Recommendations + +This Recommendation uses the following terms defined in other Recommendations: + +Synchronous Digital Hierarchy (SDH): See ITU-T Rec. G.707/Y.1322. + +Synchronous Transport Module (STM): See ITU-T Rec. G.707/Y.1322. + +Optical fibre submarine cable system: See ITU-T Rec. G.972. + +Terminal Transmission Equipment (TTE): See ITU-T Rec. G.972. + +Optical power budget: See ITU-T Rec. G.972. + +Service channel: See ITU-T Rec. G.972. + +Order wire channel: See ITU-T Rec. G.972. + +Line error ratio: See ITU-T Rec. G.972. + +Forward Error Correction (FEC): See ITU-T Rec. G.972. + +FEC frame: See ITU-T Rec. G.972. + +FEC encoder: See ITU-T Rec. G.972. + +FEC decoder: See ITU-T Rec. G.972. + +Block code: See ITU-T Rec. G.975. + +Cyclic code: See ITU-T Rec. G.975. + +Systematic code: See ITU-T Rec. G.975. + +Information word: See ITU-T Rec. G.975. + +Codeword: See ITU-T Rec. G.975. + +## 3.2 Definitions + +This Recommendation defines the following terms: + +**3.2.1 coding gain:** Coding gain means the improvement of received optical sensitivity by FEC, without considering penalty by bit rate increasing. + +**3.2.2 net coding gain:** Net coding gain means the improvement of received optical sensitivity by FEC, with considering penalty by bit rate increasing. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------|----------------------------------------| +| BCH | Bose-Chaudhuri-Hocquengham | +| BER | Bit Error Ratio | +| DWDM | Dense Wavelength Division Multiplexing | +| EDFA | Erbium-Doped Fibre Amplifier | +| FEC | Forward Error Correction | +| GF | Galois Field | +| NCG | Net Coding Gain | +| RS | Reed-Solomon | +| TTE | Terminal Transmission Equipment | +| TTI | Trail Trace Identifier | + +# 5 Super FEC features + +## 5.1 General principles of super FEC function + +In order to increase transmission bit rate, distance, and capacity utilized in the DWDM technology, the super FEC, which has more effective error correction than RS(255,239) code, could be required for the submarine optical fibre systems. + +Figure 1 outlines the fact that the encoding and decoding procedures are performed at the Terminal Transmission Equipment (TTE) level only, on electrical signals, and benefit the overall optical fibre submarine cable system, which comprises the optical fibre and possibly optical modules such as optical amplifiers using EDFA technology. + +The super FEC function essentially comprises: + +- a super FEC encoder in the transmit Terminal Transmission Equipment (TTE) that accepts information bits and adds computed redundant symbols, producing encoded data at a higher bit rate; +- a super FEC decoder in the receive Terminal Transmission Equipment (TTE) that performs the error correction while extracting the redundancy to regenerate the data that was encoded by the FEC encoder. + +The transmission signal under consideration could be STM-16, STM-64, STM-256, ODU1, ODU2, and ODU3. GbE and/or 10GbE may be required for interface of submarine TTEs. However, this does not mean that the bit rate is restricted within the above-mentioned signals. + +Several super FEC schemes, their features and correction ability are described in Appendix I. + +![Block diagram of DWDM submarine optical fibre system showing multiple wavelength channels (λ1, λ2, ..., λn) passing through optical transceivers and Super-FEC encoders/decoders, then being multiplexed and demultiplexed by an optical section with or without an optical amplifier.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +The diagram illustrates a DWDM submarine optical fibre system. It consists of two main parts: a transmitter side (top) and a receiver side (bottom), connected by an optical section (middle). + On the transmitter side, multiple input signals (labeled G.957, G.691, G.693, G.959.1, ...) enter a series of 'Optical receiver' blocks. Each 'Optical receiver' is connected to a 'Super-FEC encoder', which is in turn connected to an 'Optical transmitter'. The outputs of these transmitters are labeled λ1, λ2, ..., λn and are fed into an 'Optical multiplexer'. + The 'Optical multiplexer' output is connected to an oval labeled 'Optical section with or without optical amplifier'. + The output of the optical section is connected to an 'Optical demultiplexer'. + The 'Optical demultiplexer' outputs are labeled λ1, λ2, ..., λn and are fed into a series of 'Optical receiver' blocks. Each 'Optical receiver' is connected to a 'Super-FEC decoder', which is in turn connected to an 'Optical transmitter'. The outputs of these transmitters are the final output signals (labeled G.957, G.691, G.693, G.959.1, ...). + A small label 'G.975.1\_F01' is present in the bottom right corner of the diagram. + +Block diagram of DWDM submarine optical fibre system showing multiple wavelength channels (λ1, λ2, ..., λn) passing through optical transceivers and Super-FEC encoders/decoders, then being multiplexed and demultiplexed by an optical section with or without an optical amplifier. + +**Figure 1/G.975.1 – Block diagram of DWDM submarine optical fibre system** + +## 5.2 Super FEC scheme + +A Forward Error Correction (FEC) scheme is commonly utilized for both submarine and terrestrial optical fibre systems, which are defined in ITU-T Recs G.975 and G.709/Y.1331, respectively. In those Recommendations, Reed-Solomon (255,239) code is defined as FEC scheme. + +In order to achieve higher correction ability, several super FEC schemes are considered. For example, super FEC that uses a combination of two FEC codes is well known, such as [RS code + RS code], [BCH code + BCH code], [RS code + BCH code], etc. + +For other techniques, super FEC scheme that uses longer word length is also well known. + +# 6 Definition of super FEC function + +## 6.1 Definition + +**6.1.1 super FEC code:** Various super FEC codes are considered. RS(255,239) that is defined in ITU-T Recs G.975 and G.709/Y.1331 has 5.6 dB Net Coding Gain at $10^{-12}$ decoder output BER. This Recommendation defines the super FEC code that has higher correction ability than RS(255,239). Improvement value for super FEC compared with RS(255,239) is for further study. + +**6.1.2 outer code/Inner code:** Figure 2 shows Outer code and Inner code for super FEC scheme utilizing two concatenated FEC codes. + +![Diagram of Super FEC encoder and decoder structure. The Super FEC encoder consists of 'First FEC encoding' and 'Second FEC encoding' blocks. The Super FEC decoder consists of 'Second FEC decoding' and 'First FEC decoding' blocks. An 'Information signal' enters the first block. The output of the first block goes to the second block, which then connects to an 'EO/Fibre /OE' cloud. The output of the cloud goes to the 'Second FEC decoding' block, which then goes to the 'First FEC decoding' block, producing the final output. Feedback loops are shown: 'Inner code' from the output of the second FEC decoding block back to the input of the second FEC encoding block, and 'Outer code' from the output of the first FEC decoding block back to the input of the first FEC encoding block. The diagram is labeled G.975.1_F02.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Diagram of Super FEC encoder and decoder structure. The Super FEC encoder consists of 'First FEC encoding' and 'Second FEC encoding' blocks. The Super FEC decoder consists of 'Second FEC decoding' and 'First FEC decoding' blocks. An 'Information signal' enters the first block. The output of the first block goes to the second block, which then connects to an 'EO/Fibre /OE' cloud. The output of the cloud goes to the 'Second FEC decoding' block, which then goes to the 'First FEC decoding' block, producing the final output. Feedback loops are shown: 'Inner code' from the output of the second FEC decoding block back to the input of the second FEC encoding block, and 'Outer code' from the output of the first FEC decoding block back to the input of the first FEC encoding block. The diagram is labeled G.975.1\_F02. + +**Figure 2/G.975.1 – Outer code and inner code** + +**6.1.3 hard decision decoding:** Hard decision decoding refers to the use of a single quantization level in bit sampling, resulting in binary bit information provided to the decoding process. + +**6.1.4 soft decision decoding:** For the same received waveform, soft decision decoders make use of multiple levels of quantization (typically three or more). + +## 6.2 Super FEC code algorithm + +A super FEC algorithm depends on target features, such as correction ability, latency, etc. Detailed algorithms for super FEC code are described in Appendix I. + +## 6.3 Properties for super FEC code + +Super FEC properties depend on its FEC scheme. One super FEC scheme may take pride in higher correction ability, other super FEC schemes may show lower latency. Detailed properties for super FEC codes are described in Appendix I. + +## 6.4 Super FEC frame structure + +Frame structures are described in Appendix I. + +# 7 Parameters for super FEC + +The super FEC code is defined in several aspects, such as the feasibility of circuit operation speed, requirement from system transaction delay and theoretical optimum redundancy ratio. Each condition is described in the following subclauses. The parameters described in this clause are represented in Appendix I. + +## 7.1 Correction ability + +Error correction ability is indicated by various parameters, such as BER characteristics, net-coding gain, etc. Though all parameters are closely related, each indication is useful for the estimation of super FEC code. The following parameters should be described for each super FEC code in Appendix I. + +### 7.1.1 BER characteristics + +A BER characteristic for FEC is shown as relation between BER of decoder input signal and BER of corrected output signal. This BER improvement by FEC is the most interesting characteristics and indicates FEC correction ability. + +### 7.1.2 Coding gain + +In the case of randomly distributed errors within the encoded line signal, a FEC decoder reduces the line or raw BERin ( $B_{in}$ ) to a required reference BER ( $B_{ref}$ ) value within the payload signal. Coding gain could therefore be regarded as the relation of these Bit Error Ratios. In order to define a coding + +gain parameter as a more system related parameter, the BER reduction by the FEC is usually transformed into a dB value based on a theoretical reference system. It is common practice to define the coding gain as the reduction of signal-to-noise ratio at a reference BER. + +$$Coding\_Gain = 20 \log_{10} \left[ \operatorname{erfc}^{-1} (2B_{ref}) \right] - 20 \log_{10} \left[ \operatorname{erfc}^{-1} (2B_{in}) \right] \quad (\text{dB})$$ + +### 7.1.3 Net coding gain + +NCG is characterized by both the code rate $R$ ( $R < 1$ , the code rate $R$ is the ratio of bit rate without FEC to bit rate with FEC) and the maximum allowable $BER_{in}$ ( $B_{in}$ ) of the input signal of the FEC decoder, which can be reduced to a reference $BER_{out} = B_{ref}$ by applying the FEC algorithm. Furthermore, NCG should refer to a binary symmetric channel with added white Gaussian noise: + +$$Net\_Coding\_Gain = 20 \log_{10} \left[ \operatorname{erfc}^{-1} (2B_{ref}) \right] - 20 \log_{10} \left[ \operatorname{erfc}^{-1} (2B_{in}) \right] + 10 \log_{10} R \quad (\text{dB})$$ + +with $\operatorname{erfc}^{-1}$ the inverse of the complementary error function, $\operatorname{erfc}(x) = 1 - \operatorname{erf}(x)$ . + +### 7.1.4 Q limit + +Q limit means the minimum required allowable Q factor of the input signal for the receiver decision circuit in order to achieve a reference BER ( $B_{ref} \approx BER_{out}$ ). The Q factor is the signal-to-noise ratio at the decision circuit in voltage or current units, and is typically expressed by: + +$$Q = \frac{\mu_1 - \mu_0}{\sigma_1 + \sigma_0}$$ + +$\mu_{1/0}$ The mean value of the marks/spaces voltages or currents + +$\sigma_{1/0}$ The standard deviations of the marks/spaces voltages or currents + +The mathematical relations to BER (in case of non-FEC operation) when the threshold is set to the optimum value are: + +$$BER = \frac{1}{2} \operatorname{erfc} \left( \frac{Q}{\sqrt{2}} \right)$$ + +Table 1 is a summary table format for correction ability of a super FEC scheme of the above parameters. In order to clarify correction ability, all values should be put into the table. Summary tables for correction ability are described in Appendix I. + +**Table 1/G.975.1 – Summary table format for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|-----------|------------|----------------------|------------------|--------------| +| | $10^{-9}$ | | | | +| | $10^{-10}$ | | | | +| | $10^{-11}$ | | | | +| | $10^{-12}$ | | | | +| | $10^{-13}$ | | | | +| | $10^{-14}$ | | | | +| | $10^{-15}$ | | | | + +## 7.2 Redundancy ratio + +The redundancy ratio depends on the super-FEC methods. It describes the ratio between the number of information bits covered by the FEC and the number of bits after encoding comprising the same information plus the added redundancy information. It does not take into account any management overhead or stuffing, like as described by ITU-T Rec. G.709/Y.1331. + +Some methods have the same redundancy ratio as ITU-T Recs G.709/Y.1331 or G.975, even though the correction ability is better than those. + +## 7.3 Latency + +FEC transaction may introduce transmission delay for FEC encoding, decoding, interleaving and de-interleaving. This delay may be described as a physical time value for a given transmission rate. Alternatively, it may be given as the number of intermediately stored information bits while in the process of encoding/decoding. In most cases, this second number is independent of the actual transmission rate. + +# 8 Supervision + +When definition of super FEC frames, OH (OverHead) functions shall be described to achieve some maintenance function. These functions that are described in this clause are used for measuring the transmission performance. A concrete way is, however, for further study. + +## 8.1 Signal quality supervision + +To evaluate the transmission condition, some error counting technique is required, such as BIP error counting or counting for the number of FEC error correction bit. Performance monitoring using error counting is mandatory for this Recommendation. + +## 8.2 Connectivity supervision + +To prevent miss-connection, trail trace such as TTI is needed. + +# Appendix I + +## Super FEC schemes + +## I.1 Overview + +Table I.1 shows an overview of super FEC schemes that are described in this appendix. Each super FEC scheme is described in the subclause that is represented in Table I.1. + +**Table I.1/G.975.1 – Overview of super FEC schemes** + +| Subclause | FEC scheme | | +|-----------|----------------------------------|---------------------------------------------------------------------------| +| | Concatenated or non-concatenated | Used FEC code | +| I.2 | Concatenated FEC | Outer code: RS(255,239)
Inner code: CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) | +| I.3 | Concatenated FEC | Outer code: BCH(3860,3824)
Inner code: BCH(2040,1930) | + +**Table I.1/G.975.1 – Overview of super FEC schemes** + +| Subclause | FEC scheme | | +|-----------|---------------------------------------------|-------------------------------------------------------------------------------------------------| +| | Concatenated or non-concatenated | Used FEC code | +| I.4 | Concatenated FEC | Outer code: RS(1023,1007)
Inner code: BCH(2047,1952) | +| I.5 | Concatenated FEC
(Soft Decision capable) | Outer code: RS(1901,1855)
Inner code:
Extended Hamming Product Code (512,502) × (510,500) | +| I.6 | Non-concatenated FEC | LDPC Code | +| I.7 | Concatenated FEC | Two orthogonally concatenated BCH codes | +| I.8 | Non-concatenated FEC | RS(2720,2550) | +| I.9 | Concatenated FEC | Two interleaved extended BCH(1020,988) codes | + +## **I.2 RS(255,239)/CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) super FEC code** + +### **I.2.1 Overview** + +This clause describes a super-FEC scheme, which provides higher error correction capability than RS(255,239) code. Figure I.1 shows the super-FEC scheme. The super-FEC scheme uses concatenated RS and convolutional self-orthogonal code (CSOC). RS(255,239) is used as the outer code. CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) is used as the inner code, where $k_0$ is the number of bits to be encoded, $n_0$ is the number of coded bits and $J$ is the number of orthogonal check sets. The interleaver and deinterleaver are used between the inner and outer code. + +Concatenated codes can apply iterative decoding. Also, CSOCs can apply iterative decoding independently. These techniques can improve the error correction capability without increasing the coding rate. The number of iteration is vendor specific. + +The super-FEC scheme provides 7.95 dB net coding gain at 1E-12 corrected BER with 24.48% redundancy, by using three times iterative CSOC decoding. + +![Block diagram of the Super-FEC scheme showing the flow from RS(255,239) encoder to CSOC encoder, then to a transmission line, and the corresponding decoding path with iterative loops.](16c1175b5f05a4b55e6d396fc51b15b3_img.jpg) + +``` + +graph LR + In(( )) --> RS_Enc[RS(255,239) encoder] + RS_Enc --> Int1[Interleaver] + Int1 --> CSOC_Enc["CSOC encoder (n0/k0=7/6, J=8)"] + CSOC_Enc --> TL[Transmission line] + TL --> CSOC_Dec["CSOC Decoder (n0/k0=7/6, J=8)"] + CSOC_Dec -- CSOC iteration path --> CSOC_Dec + CSOC_Dec --> DeInt[De-interleaver] + DeInt --> RS_Dec[RS(255,239) decoder] + RS_Dec -- Concatenated code iteration path --> Int2[Interleaver] + Int2 --> CSOC_Dec + RS_Dec --> Out(( )) + +``` + +The diagram illustrates the Super-FEC scheme. The encoding path consists of an input signal entering an 'RS(255,239) encoder' block, followed by an 'Interleaver' block, and then a 'CSOC encoder ( $n_0/k_0=7/6, J=8$ )' block. The output of the CSOC encoder is sent to a 'Transmission line'. The decoding path starts from the transmission line and goes through a 'CSOC Decoder ( $n_0/k_0=7/6, J=8$ )' block. This decoder has two iteration paths: a 'CSOC iteration path' that loops back to its input, and a 'Concatenated code iteration path' that goes through an 'Interleaver' block and then into an 'RS(255,239) decoder' block. The output of the RS(255,239) decoder is the final output signal. A small label 'G.975.1\_FI.1' is present in the bottom right corner of the diagram. + +Block diagram of the Super-FEC scheme showing the flow from RS(255,239) encoder to CSOC encoder, then to a transmission line, and the corresponding decoding path with iterative loops. + +**Figure I.1/G.975.1 – Super-FEC scheme** + +### **I.2.2 FEC algorithm** + +The super-FEC scheme uses concatenated RS(255,239) and CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ). The detailed specification of RS(255,239), CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) and frame structure are described in I.2.2.3. + +#### I.2.2.1 RS(255,239) code + +The RS(255,239) code is a non-binary code (the FEC algorithm operates on 8-bit symbols) and belongs to the family of systematic linear cyclic block codes. + +The generator polynomial of the code is given by: + +$$G(D) = \prod_{i=0}^{15} (D - \alpha^i) \quad (I-1)$$ + +where $\alpha$ is a root of the binary primitive polynomial $x^8 + x^4 + x^3 + x^2 + 1$ . A data byte ( $d_7, d_6, \dots, d_1, d_0$ ) is identified with the element $d_7 \cdot \alpha^7 + d_6 \cdot \alpha^6 + \dots + d_1 \cdot \alpha^1 + d_0$ in GF (256), the finite field with 256 elements. The RS(255,239) codeword consists of 239 information bytes and 16 parity bytes. The RS(255,239) can correct up to 8 symbol errors in a single codeword. + +#### I.2.2.2 CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) code + +CSOCs are defined by their generator polynomials. The super-FEC code applies following generator polynomials. + +$$\begin{aligned} G^{(5)}(D) &= 1 + D^{35} + D^{80} + D^{119} + D^{161} + D^{193} + D^{209} + D^{269} \\ G^{(4)}(D) &= 1 + D^{87} + D^{173} + D^{192} + D^{197} + D^{217} + D^{251} + D^{258} \\ G^{(3)}(D) &= 1 + D^{31} + D^{82} + D^{93} + D^{94} + D^{96} + D^{200} + D^{218} \\ G^{(2)}(D) &= 1 + D^{91} + D^{99} + D^{114} + D^{120} + D^{166} + D^{170} + D^{297} \\ G^{(1)}(D) &= 1 + D^{13} + D^{22} + D^{49} + D^{77} + D^{348} + D^{385} + D^{418} \\ G^{(0)}(D) &= 1 + D^{69} + D^{95} + D^{112} + D^{142} + D^{152} + D^{210} + D^{263} \end{aligned} \quad (I-2)$$ + +Figure I.2 shows CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) encoding and decoding scheme. The CSOC encoder appends a parity bit to each group of six information bits, and transmits seven coded bits in sequence. The parity sequence $P(D)$ is expressed as: + +$$P(D) = \sum_{i=0}^5 M^{(i)}(D) G^{(i)}(D) \quad (I-3)$$ + +where $M^{(i)}(D)$ is the information sequence. + +The CSOC decoder generates parity checksum sequence $S(D)$ using an encoder replica. Parity checksum sequence $S(D)$ is calculated as: + +$$\begin{aligned} S(D) &= [P(D) + F(D)] + \sum_{i=0}^5 [M^{(i)}(D) + E^{(i)}(D)] G^{(i)}(D) \\ &= \left[ \sum_{i=0}^5 M^{(i)}(D) G^{(i)}(D) + F(D) \right] + \sum_{i=0}^5 [M^{(i)}(D) + E^{(i)}(D)] G^{(i)}(D) \\ &= \sum_{i=0}^5 E^{(i)}(D) G^{(i)}(D) + F(D) \end{aligned} \quad (I-4)$$ + +where $E^{(i)}(D)$ is the error sequence on the information sequence $M^{(i)}(D)$ . $F(D)$ is the error sequence on the parity sequence. + +CSOC ( $n_0/k_0 = 7/6$ , $J = 8$ ) supplies six sets of eight orthogonal parity checksums. A set is used to check one information bit. The information bit is estimated to be error by threshold decoder if the number of parity checksum equal to one in the set is threshold value (Th) and over. Threshold value + +should be more than $J/2$ . CSOCs can apply iterative decoding. Threshold value of each iteration can be determined independently. + +![Block diagram of CSOC encoder and decoder. The CSOC encoder takes Information M(D) (k0 bits) and generates Parity P(D) (1 Bit) using a Convolutional encoder G(D). The encoder output is transmitted through a channel where it is corrupted by F(D) and E(D). The CSOC decoder receives the corrupted signal and uses an Encoder replica to generate a parity checksum register. The decoder also uses a Parity register and a Threshold decoder to correct the information. The final output is Corrected information. The diagram is labeled G.975.1_F1.2.](5cab96b2d23174c25919840ecd50aa48_img.jpg) + +The diagram illustrates the CSOC encoder and decoder architecture. On the left, the CSOC encoder takes an information sequence $M(D)$ of $k_0$ bits as input. This is processed by a Convolutional encoder $G(D)$ to produce a parity bit $P(D)$ . The encoder's output, consisting of the information $M(D)$ and the parity $P(D)$ , is transmitted through a channel. In the channel, the signal is corrupted by $F(D)$ and $E(D)$ . The received signal is then processed by the CSOC decoder. The decoder contains an Encoder replica that takes the received information $M(D)+E(D)$ and generates a parity checksum register. The decoder also includes a Parity register and a Threshold decoder. The Threshold decoder outputs a corrected information sequence of $k_0$ bits. The diagram is labeled G.975.1\_F1.2. + +Block diagram of CSOC encoder and decoder. The CSOC encoder takes Information M(D) (k0 bits) and generates Parity P(D) (1 Bit) using a Convolutional encoder G(D). The encoder output is transmitted through a channel where it is corrupted by F(D) and E(D). The CSOC decoder receives the corrupted signal and uses an Encoder replica to generate a parity checksum register. The decoder also uses a Parity register and a Threshold decoder to correct the information. The final output is Corrected information. The diagram is labeled G.975.1\_F1.2. + +Figure I.2/G.975.1 – CSOCs encoder and decoder + +#### I.2.2.3 Frame structure + +Figure I.3 shows frame format fed from RS encoder to interleaver. This frame format is named "RS frame format" for convenience sake. RS frame format consists of 16 RS(255,239) codewords. + +Figure I.4 shows frame format fed from interleaver to CSOC encoder. This frame format is named "interleaved RS frame format". + +Figure I.5 shows frame format fed from CSOC encoder to transmission line. This frame format is named "CSOC frame format". $m_j^{(i)}$ means $j$ degree coefficient of information sequence polynomial $M^{(i)}(D)$ . $p_j$ means $j$ degree coefficient of parity sequence polynomial $P(D)$ . Note that CSOC encoders do not process termination at frame boundary. + +![Diagram of RS frame format showing a grid of 255 columns and 128 rows. The grid is divided into information data (239 bits) and parity data (16 bits). Rows are labeled row 1 to row 128. Columns are labeled Column 1, Column 2, Column 240, and Column 255. The RS frame format is shown below the grid, with columns 1 to 255 mapped to a frame length of 32640 bits. The mapping is: column 1 to 8*16, column 2 to 8*16 + 1, columns 3 to 239 to 16*16, columns 240 to 255 to 1912*16, and the final part to 1920*16 and 2040*16. The diagram also shows the input order and the RS(255,239) codeword structure.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +Input order + +Row length = 255 bits + +Information data 239 bits + +Parity data 16 bits + +# codeword number + +MSB + +RS(255,239) codeword #1 + +LSB + +MSB + +RS(255,239) codeword #16 + +LSB + +row 1 +row 2 +row 3 +row 4 +row 5 +row 6 +row 7 +row 8 +row 9 +row 10 + +Column 1 +Column 2 +Column 240 +Column 255 + +row 121 +row 122 +row 123 +row 124 +row 125 +row 126 +row 127 +row 128 + +RS frame format + +1 + +$8*16$ + +$8*16 + 1$ + +$16*16$ + +$1912*16$ + +$1920*16$ + +$2040*16$ + +column 1 + +column 2 + +Information data + +column 239 + +column 240 + +Parity data + +column 255 + +Frame length = 32640 bits + +G.975.1\_Fl.3 + +Diagram of RS frame format showing a grid of 255 columns and 128 rows. The grid is divided into information data (239 bits) and parity data (16 bits). Rows are labeled row 1 to row 128. Columns are labeled Column 1, Column 2, Column 240, and Column 255. The RS frame format is shown below the grid, with columns 1 to 255 mapped to a frame length of 32640 bits. The mapping is: column 1 to 8\*16, column 2 to 8\*16 + 1, columns 3 to 239 to 16\*16, columns 240 to 255 to 1912\*16, and the final part to 1920\*16 and 2040\*16. The diagram also shows the input order and the RS(255,239) codeword structure. + +**Figure I.3/G.975.1 – RS frame format** + +![Diagram of interleaved RS frame format showing a grid of 255 symbols per frame. The grid is divided into RS frames and interleaved RS frames. The diagram shows the mapping of symbols from RS frames to interleaved RS frames. The mapping is: RS frame #n-7 to interleaved RS frame #n, RS frame #n-6 to interleaved RS frame #n+1, RS frame #n-5 to interleaved RS frame #n, RS frame #n-4 to interleaved RS frame #n+1, RS frame #n-3 to interleaved RS frame #n, RS frame #n-2 to interleaved RS frame #n+1, RS frame #n-1 to interleaved RS frame #n, RS frame #n to interleaved RS frame #n+1, RS frame #n+1 to interleaved RS frame #n. The diagram also shows the input order and the output order.](2cde062fd82833415971a8bd1a2cafab_img.jpg) + +Frame length = 32640 bits = 255 symbols + +1 symbol = 128 bits + +# frame number + +#n-7 +#n-6 +#n-5 +#n-4 +#n-3 +#n-2 +#n-1 +#n +#n+1 + +RS frame + +Interleaver input order + +Interleaved RS frame + +#n +#n+1 + +Interleaver output order + +G.975.1\_Fl.4 + +Diagram of interleaved RS frame format showing a grid of 255 symbols per frame. The grid is divided into RS frames and interleaved RS frames. The diagram shows the mapping of symbols from RS frames to interleaved RS frames. The mapping is: RS frame #n-7 to interleaved RS frame #n, RS frame #n-6 to interleaved RS frame #n+1, RS frame #n-5 to interleaved RS frame #n, RS frame #n-4 to interleaved RS frame #n+1, RS frame #n-3 to interleaved RS frame #n, RS frame #n-2 to interleaved RS frame #n+1, RS frame #n-1 to interleaved RS frame #n, RS frame #n to interleaved RS frame #n+1, RS frame #n+1 to interleaved RS frame #n. The diagram also shows the input order and the output order. + +**Figure I.4/G.975.1 – Interleaved RS frame format** + +![Figure I.5/G.975.1 – CSOC frame format. This diagram illustrates the mapping of interleaved RS frames to CSOC frames. At the top, three interleaved RS frames are shown: #n-1, #n, and #n+1. Each RS frame has a length of 32640 bits, which is equivalent to 5440 * 6 bits. Each RS frame is divided into 6-bit segments. Below this, the corresponding CSOC frames are shown: #n-1, #n, and #n+1. Each CSOC frame has a length of 38080 bits, which is equivalent to 5440 * 7 bits. Each CSOC frame is divided into 7-bit segments. The mapping shows that each 6-bit segment from an RS frame is mapped to a 7-bit segment in a CSOC frame. The data within each frame is represented as a sequence of symbols: m_j^{(0)}, m_j^{(1)}, m_j^{(2)}, m_j^{(3)}, m_j^{(4)}, m_j^{(5)}, and P_j. The index j for the symbols in CSOC frame #n ranges from 0 to 5440*(n-1). The diagram is labeled with 'G.975.1_FI.5' and '# Frame number'.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Figure I.5/G.975.1 – CSOC frame format. This diagram illustrates the mapping of interleaved RS frames to CSOC frames. At the top, three interleaved RS frames are shown: #n-1, #n, and #n+1. Each RS frame has a length of 32640 bits, which is equivalent to 5440 \* 6 bits. Each RS frame is divided into 6-bit segments. Below this, the corresponding CSOC frames are shown: #n-1, #n, and #n+1. Each CSOC frame has a length of 38080 bits, which is equivalent to 5440 \* 7 bits. Each CSOC frame is divided into 7-bit segments. The mapping shows that each 6-bit segment from an RS frame is mapped to a 7-bit segment in a CSOC frame. The data within each frame is represented as a sequence of symbols: m\_j^{(0)}, m\_j^{(1)}, m\_j^{(2)}, m\_j^{(3)}, m\_j^{(4)}, m\_j^{(5)}, and P\_j. The index j for the symbols in CSOC frame #n ranges from 0 to 5440\*(n-1). The diagram is labeled with 'G.975.1\_FI.5' and '# Frame number'. + +Figure I.5/G.975.1 – CSOC frame format + +### I.2.3 Error correction ability + +Error correction ability of the super-FEC code depends on the number of iteration times and threshold values of CSOC decoder. Figure I.6 shows an example of the super-FEC decoder. This decoder iterates CSOC decoding three times. The threshold value of the first, second and third CSOC decoder is seven, six and five respectively. Table I.2 and Figure I.7 show summary of error correction ability. Figure I.7 shows a comparison of error correction ability between RS(255,239) and super-FEC decoder. + +![Figure I.6/G.975.1 – An example of the super-FEC decoder. This block diagram shows the decoding process. On the right, 'Received data' enters an 'Iterative CSOC decoder' block. This block contains three stages: '1st CSOC decoder (r=6/7, J=8, Th=7)', '2nd CSOC decoder (r=6/7, J=8, Th=6)', and '3rd CSOC decoder (r=6/7, J=8, Th=5)'. The output of the 3rd CSOC decoder goes to a 'De-interleaver' block. The output of the De-interleaver then goes to an 'RS(255,239) decoder' block, which finally outputs 'Corrected data'. The diagram is labeled with 'G.975.1_FI.6'.](9b9d2abd741ed4bafe7f78f89961c663_img.jpg) + +Figure I.6/G.975.1 – An example of the super-FEC decoder. This block diagram shows the decoding process. On the right, 'Received data' enters an 'Iterative CSOC decoder' block. This block contains three stages: '1st CSOC decoder (r=6/7, J=8, Th=7)', '2nd CSOC decoder (r=6/7, J=8, Th=6)', and '3rd CSOC decoder (r=6/7, J=8, Th=5)'. The output of the 3rd CSOC decoder goes to a 'De-interleaver' block. The output of the De-interleaver then goes to an 'RS(255,239) decoder' block, which finally outputs 'Corrected data'. The diagram is labeled with 'G.975.1\_FI.6'. + +Figure I.6/G.975.1 – An example of the super-FEC decoder + +**Table I.2/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|-----------|------------|----------------------|------------------|--------------| +| 6.50E-03 | 1.00E-09 | 6.70 | 7.66 | 7.9022 | +| 6.30E-03 | 1.00E-10 | 7.19 | 8.13 | 7.9410 | +| 6.05E-03 | 1.00E-11 | 7.59 | 8.54 | 7.9908 | +| 5.80E-03 | 1.00E-12 | 7.95 | 8.90 | 8.0421 | +| 5.60E-03 | 1.00E-13 | 8.29 | 9.24 | 8.0843 | +| 5.40E-03 | 1.00E-14 | 8.60 | 9.55 | 8.1278 | +| 5.20E-03 | 1.00E-15 | 8.88 | 9.83 | 8.1724 | +| 5.00E-03 | 1.00E-16 | 9.12 | 10.07 | 8.2183 | + +![Figure I.7/G.975.1 – BER characteristics of the super-FEC decoder. This is a log-log plot showing Output BER versus Input BER. The x-axis (Input BER) ranges from 10^-5 to 10^-2. The y-axis (Output BER) ranges from 10^-16 to 10^0. Three curves are shown: 'Uncoded' (dashed line), 'RS(255,239)' (dashed line), and 'Super FEC' (solid line with open circles for measured data). The 'Uncoded' curve shows a linear relationship on the log-log scale. The 'RS(255,239)' curve shows a sharp drop in Output BER around an Input BER of 10^-4. The 'Super FEC' curve shows a sharp drop in Output BER around an Input BER of 10^-3, indicating a lower error floor and better performance than RS(255,239).](7bed2d7c96d86bf922295a1252da52a5_img.jpg) + +Figure I.7/G.975.1 – BER characteristics of the super-FEC decoder. This is a log-log plot showing Output BER versus Input BER. The x-axis (Input BER) ranges from 10^-5 to 10^-2. The y-axis (Output BER) ranges from 10^-16 to 10^0. Three curves are shown: 'Uncoded' (dashed line), 'RS(255,239)' (dashed line), and 'Super FEC' (solid line with open circles for measured data). The 'Uncoded' curve shows a linear relationship on the log-log scale. The 'RS(255,239)' curve shows a sharp drop in Output BER around an Input BER of 10^-4. The 'Super FEC' curve shows a sharp drop in Output BER around an Input BER of 10^-3, indicating a lower error floor and better performance than RS(255,239). + +**Figure I.7/G.975.1 – BER characteristics of the super-FEC decoder** + +### I.2.4 Redundancy ratio + +The redundancy ratio of the super-FEC code is 24.48%. + +### I.2.5 Latency + +The super-FEC code has an around 25 $\mu\text{s}$ delay for 10 Gbit/s payload throughput, typically. + +### I.2.6 Property + +The super-FEC code has an advantage of low complexity. It is well known that CSOC has an advantage of simple implementation. + +## I.3 Concatenated BCH super FEC codes + +### I.3.1 Overview + +This clause describes a super-FEC scheme, which provides higher error correction capability than RS(255,239) code. Figure I.8 shows the super-FEC scheme. The super-FEC scheme uses + +concatenated BCH codes. BCH(3860,3824) is used as the outer code. BCH(2040,1930) is used as the inner code. The interleaver and de-interleaver are used between the inner and outer code. + +Concatenated codes can apply iterative decoding. This technique can improve the error correction capability without increasing the coding rate. The number of iteration is vendor specific. + +The super-FEC scheme provides 7.98 dB net coding gain at 1E-12 corrected BER with 6.69% redundancy, by using three times iterative decoding. + +![Figure I.8/G.975.1 – Super-FEC scheme. The diagram shows the encoding and decoding process. On the top (encoding) path, 'Payload data' enters a 'BCH(3860,3824) encoder', followed by an 'Interleaver', then a 'BCH(2040,1930) Encoder', which outputs to a 'Transmission line'. On the bottom (decoding) path, the signal from the transmission line enters a 'BCH(2040,1930) decoder', followed by a 'De-interleaver', then a 'BCH(3860,3824) decoder', which outputs 'Corrected payload data'. An 'Iteration path' is shown at the bottom, consisting of an 'Interleaver' block that receives input from the 'Corrected payload data' output and feeds back into the 'BCH(2040,1930) decoder' via a switch mechanism. The label 'G.975.1_FI.8' is in the bottom right corner.](81a4cbf0b3c4cbc065efdf8f800dadde_img.jpg) + +Figure I.8/G.975.1 – Super-FEC scheme. The diagram shows the encoding and decoding process. On the top (encoding) path, 'Payload data' enters a 'BCH(3860,3824) encoder', followed by an 'Interleaver', then a 'BCH(2040,1930) Encoder', which outputs to a 'Transmission line'. On the bottom (decoding) path, the signal from the transmission line enters a 'BCH(2040,1930) decoder', followed by a 'De-interleaver', then a 'BCH(3860,3824) decoder', which outputs 'Corrected payload data'. An 'Iteration path' is shown at the bottom, consisting of an 'Interleaver' block that receives input from the 'Corrected payload data' output and feeds back into the 'BCH(2040,1930) decoder' via a switch mechanism. The label 'G.975.1\_FI.8' is in the bottom right corner. + +**Figure I.8/G.975.1 – Super-FEC scheme** + +### I.3.2 FEC algorithm + +The super-FEC scheme uses concatenated BCH(3860,3824) and BCH(2040,1930). The detailed specification of BCH(3860,3824), BCH(2040,1930) and frame structure are described in I.3.2.3. + +#### I.3.2.1 BCH(3860,3824) code + +The BCH(3860,3824) code is a binary code. The generator polynomial of the code is given by: + +$$G(x) = M_1(x)M_3(x)M_5(x)$$ + +$$M_i(x) = \prod_{j=1}^{12} (x - \alpha^{i^*j})$$ + +where $M_i(x)$ are minimal polynomials and $\alpha$ is a root of the binary primitive polynomial $x^{12} + x^{11} + x^8 + x^6 + 1$ . The BCH(3860,3824) codeword consists of 3824 information bits and 36 parity bits. The BCH(3860,3824) can correct up to 3 bit errors in a single codeword. + +#### I.3.2.2 BCH(2040,1930) code + +The BCH(2040,1930) code is a binary code. The generator polynomial of the code is given by: + +$$G(x) = M_1(x)M_3(x)M_5(x)M_7(x)M_9(x)M_{11}(x)M_{13}(x)M_{15}(x)M_{17}(x)M_{19}(x)$$ + +$$M_i(x) = \prod_{j=1}^{11} (x - \alpha^{i^*j})$$ + +where $M_i(x)$ are minimal polynomials and $\alpha$ is a root of the binary primitive polynomial $x^{11} + x^2 + 1$ . The BCH(2040,1930) codeword consists of 1930 information bits and 110 parity bits. The BCH(2040,1930) can correct up to 10 bit errors in a single codeword. + +#### I.3.2.3 Frame structure + +Figure I.9 shows frame format fed from BCH(3860,3824) encoder to interleaver. This frame format is named "BCH(3860,3824) frame format" for convenience sake. BCH(3860,3824) frame format + +consists of eight BCH(3860,3824) codewords. One BCH(3860,3824) codeword consists of 3824 information bits and 36 parity bits. + +Figure I.10 shows frame format fed from interleaver to BCH(2040,1930) encoder. This frame format is named "interleaved BCH(3860,3824) frame format". + +Figure I.11 shows frame format fed from BCH(2040,1930) encoder to transmission line. BCH(2040,1930) encoder replaces dummy data of BCH(3860,3824) frame to parity check data. BCH(2040,1930) frame format consists of 16 BCH(2040,1930) codewords. One BCH(2040,1930) codeword consists of 1930 information bits and 110 parity bits. The information bits consist of 1912 payload bits and 18 parity bits of BCH(3860,3824). + +![Diagram of BCH(3860,3824) frame format showing input order, row/column structure, and output order mapping.](79e1709a7317ead45379cbb8ff3ba802_img.jpg) + +The diagram illustrates the mapping of bits from an input order to an output order for the BCH(3860,3824) frame format. At the top, an 'Input order' arrow points to a grid representing a codeword structure with 'Row length = 3860 bits'. This grid is divided into 'Information data = payload data (3824 bits)' and 'Parity data (36 bits)'. Rows are labeled 'row 1' through 'row 8', and columns include 'column 1', 'column 2', 'column 3825', 'column 3856', 'column 3857', 'column 3858', 'column 3859', and 'column 3860'. Below this, the 'BCH(3860,3824) frame format' is shown as a sequence of columns: 'column 1', 'column 2', 'column 3824' (labeled '3824\*8'), 'column 3825' (labeled '3825\*8'), 'column 3856' (labeled '3856\*8'), 'Parity data 32 bits + dummy data 92 bits', and 'Dummy data 1668 bits'. These are further grouped into 'Payload data 30592 bits', 'parity data 256 bits', and 'Frame length = 32640 bits'. The bottom section shows the 'output order' mapping, which interleaves bits from different rows and columns into a sequence of '2 bits' and '6 dummy bits' blocks, corresponding to 'row 1 column 3857-58', 'row 1 column 3859-60', 'row 2 column 3857-58', and 'row 2 column 3859-60'. + +Diagram of BCH(3860,3824) frame format showing input order, row/column structure, and output order mapping. + +Figure I.9/G.975.1 – BCH(3860,3824) frame format + +![Diagram of Interleaved BCH(3860,3824) frame format showing frame numbers, symbol mapping, and interleaver input/output orders.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +The diagram illustrates the interleaved BCH(3860,3824) frame format. At the top, it states "Frame length = 32640 bits = 255 symbols" and "1 symbol = 128 bits". + +The vertical axis on the left lists frame numbers: "# frame number", "#n-7", "#n-6", "#n-5", "#n-4", "#n-3", "#n-2", "#n-1", "#n", "#n+1", ":", "Interleaved BCH(3860,3824) frame", "#n", "#n+1", ":". The label "BCH(3860,3824) frame" is placed between #n-3 and #n-2. + +The horizontal axis represents 255 symbols. A grid shows the mapping of symbols from input frames to the interleaved output frame. Shaded blocks indicate the placement of symbols from frame #n-7 through #n+1 into the interleaved frame. Vertical arrows point from each of the 255 columns down to the interleaved frame row. + +On the right, "Interleaver input order" is shown with arrows pointing to the input frames in a zigzag pattern: #n-7, #n-6, #n-5, #n-4, #n-3, #n-2, #n-1, #n, #n+1, then repeating #n-7, #n-6, #n-5, #n-4, #n-3, #n-2, #n-1, #n, #n+1. Below this, "Interleaver output order" is shown with arrows pointing to the 255 symbols of the interleaved frame in sequential order from left to right. + +The diagram is labeled "G.975.1\_FI.10" in the bottom right corner. + +Diagram of Interleaved BCH(3860,3824) frame format showing frame numbers, symbol mapping, and interleaver input/output orders. + +**Figure I.10/G.975.1 – Interleaved BCH(3860,3824) frame format** + +![Diagram of BCH(2040,1930) frame format showing the mapping of codewords to a frame structure. The diagram includes a grid of rows (1-128) and columns (1-255). Rows are grouped into codewords #1, #2, and #16, with MSB and LSB markers. Columns are grouped into segments: column 1 (1 bit), column 2 (8*16+1 bits), columns 240-242 (1920*16, 1928*16, 1936*16 bits), and column 255 (2040*16 bits). The first two columns contain payload data, while the remaining columns contain parity data for BCH(3860,3824) and BCH(2040,1930). Arrows show the input and output order of bits. A legend at the bottom identifies the parity data patterns.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +Input and output order + +Row length = 255 bits + +Information data of BCH(2040,1930) + +Payload data + +Parity data of BCH(3860,3824) + +Parity data of BCH(2040,1930) + +# codeword number + +MSB + +BCH(2040,1930) codeword #1 + +LSB + +MSB + +BCH(2040,1930) codeword #2 + +LSB + +MSB + +BCH(2040,1930) codeword #16 + +LSB + +row 1 + +row 2 + +row 3 + +row 4 + +row 5 + +row 6 + +row 7 + +row 8 + +row 9 + +row 10 + +row 11 + +row 12 + +row 13 + +row 14 + +row 15 + +row 16 + +Column 1 + +Column 2 + +Column 240 + +Column 241 + +Column 242 + +Column 255 + +row 121 + +row 122 + +row 123 + +row 124 + +row 125 + +row 126 + +row 127 + +row 128 + +BCH(2040,1930) frame format + +1 + +8\*16 + +8\*16+1 + +16\*16 + +1920\*16 + +1928\*16 + +1936\*16 + +2040\*16 + +column 1 + +column 2 + +column 240 + +column 241 + +column 242 + +column 255 + +Frame length = 32640 bits + +G.975.1\_FI.11 + +Parity data of BCH(3860,3824) + +Parity data of BCH(2040,1930) + +Diagram of BCH(2040,1930) frame format showing the mapping of codewords to a frame structure. The diagram includes a grid of rows (1-128) and columns (1-255). Rows are grouped into codewords #1, #2, and #16, with MSB and LSB markers. Columns are grouped into segments: column 1 (1 bit), column 2 (8\*16+1 bits), columns 240-242 (1920\*16, 1928\*16, 1936\*16 bits), and column 255 (2040\*16 bits). The first two columns contain payload data, while the remaining columns contain parity data for BCH(3860,3824) and BCH(2040,1930). Arrows show the input and output order of bits. A legend at the bottom identifies the parity data patterns. + +Figure I.11/G.975.1 – BCH(2040,1930) frame format + +### I.3.3 Error correction ability + +Error correction ability of the super-FEC code depends on the number of iteration times. Table I.3 and Figure I.12 show error correction ability when using three times iterative decoding. + +**Table I.3/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|-----------|------------|----------------------|------------------|--------------| +| 3.50E-03 | 1.00E-09 | 6.66 | 6.94 | 8.6171 | +| 3.44E-03 | 1.00E-10 | 7.15 | 7.44 | 8.6356 | +| 3.37E-03 | 1.00E-11 | 7.59 | 7.87 | 8.6575 | +| 3.30E-03 | 1.00E-12 | 7.98 | 8.26 | 8.6798 | +| 3.25E-03 | 1.00E-13 | 8.35 | 8.63 | 8.6959 | +| 3.20E-03 | 1.00E-14 | 8.68 | 8.96 | 8.7123 | +| 3.15E-03 | 1.00E-15 | 8.99 | 9.27 | 8.7288 | +| 3.10E-03 | 1.00E-16 | 9.26 | 9.54 | 8.7455 | + +![Figure I.12/G.975.1 – BER characteristics of the super-FEC decoder. This is a log-log plot showing Output BER versus Input BER. The x-axis (Input BER) ranges from 10^-5 to 10^-2. The y-axis (Output BER) ranges from 10^-16 to 10^0. Three curves are shown: 'Uncoded' (a dashed line with a slope of 1), 'RS(255,239)' (a dashed line that is flat at 10^-10 for input BERs between 10^-5 and 10^-4), and 'Super FEC' (a solid line with open circles representing measured data). The Super FEC curve shows a sharp drop in output BER starting around an input BER of 10^-3, reaching a floor of approximately 10^-14. A legend box for 'Super FEC' indicates that the solid line is 'Simulation' and the open circles are 'Measured'. The label 'G.975.1_FI.12' is in the bottom right corner.](485c57a6add7e0bd7898009db1179ee6_img.jpg) + +Figure I.12/G.975.1 – BER characteristics of the super-FEC decoder. This is a log-log plot showing Output BER versus Input BER. The x-axis (Input BER) ranges from 10^-5 to 10^-2. The y-axis (Output BER) ranges from 10^-16 to 10^0. Three curves are shown: 'Uncoded' (a dashed line with a slope of 1), 'RS(255,239)' (a dashed line that is flat at 10^-10 for input BERs between 10^-5 and 10^-4), and 'Super FEC' (a solid line with open circles representing measured data). The Super FEC curve shows a sharp drop in output BER starting around an input BER of 10^-3, reaching a floor of approximately 10^-14. A legend box for 'Super FEC' indicates that the solid line is 'Simulation' and the open circles are 'Measured'. The label 'G.975.1\_FI.12' is in the bottom right corner. + +**Figure I.12/G.975.1 – BER characteristics of the super-FEC decoder** + +### I.3.4 Redundancy ratio + +The redundancy ratio of the super-FEC code is 6.69%. + +### I.3.5 Latency + +The super-FEC code has an around 100 µs delay for 10 Gbit/s payload throughput, typically. + +### I.3.6 Property + +The super-FEC scheme is rate adapted to G.709/Y.1331 and G.975 frame. There is no additional overhead compared to G.709/Y.1331 and G.975 frame with RS(255,239) encoding. + +## I.4 RS(1023,1007)/BCH(2047,1952) super FEC code + +### I.4.1 Overview + +This Super FEC consists of two interleaved codes: + +RS(1023,1007) parent outer code, $m = 10$ , $T = 8$ . + +BCH(2047,1952) parent inner code, $m = 11$ , $T = 8$ . + +These two interleaved codes are targeted at providing additional coding gain on the standard G.709/Y.1331 ODU payload while maintaining the exact data rates at the G.709/Y.1331 OTU, i.e., 7% overhead. + +### I.4.2 Super FEC algorithm + +#### I.4.2.1 Code interleaving + +The ODU payload consists of $16 \times 239 \times 4 \times 8$ bits = 122368 bits in total. These 122368 bits are divided into 16 groups and are then encoded with 15 RS(781,765) and one RS(778,762) code, both of which are shortened codes of the parent code listed above. Note that the parent code above operates on an $m = 10$ Galois Field, so data are grouped into dectets and are operated on accordingly. If we number the ODU payload bits as odu[0], odu[1] up to odu[122367], then the interleaving can be clearly explained. Keep in mind that odu[0] is the first transmitted bit, followed by odu[1] and so on up to odu[122367], i.e., in G.709/Y.1331 terms, {odu[0], odu[1], odu[2], odu[3], odu[4], odu[5], odu[6], odu[7]} = 0xf6, the first OA1 byte in the G.709/Y.1331 frame. + +Using this convention, we will now pack the odu bits into the payload portion of the RS codes. This first RS code RS[0] is an RS(781,765) over $m = 10$ . Thus we need to pack $765 \times 10$ bits into the first 765 dectets of this code. Thus bits odu[0]...odu[9] form the first dectet of the first RS code. Bits odu[10]...odu[19] form the second dectet of RS[0]. The bits are repeatedly packed into 765 dectets of RS[0] for a total of 7650 bits, i.e., odu[0]...odu[7649]. At this point, the data is then RS encoded over $m = 10$ and $T = 8$ , and 2T parity symbols are added to the code. Thus, the next $16 \times 10$ bits consist of RS parity. + +We will now consider the OTU output data. This consists of $16 \times 255 \times 4 \times 8$ bits or 130560 bits. We will number these bits otu[0]...otu[130559]. The first RS code is now mapped to the output otu, i.e., odu[0]...odu[7649] $\rightarrow$ otu[0]...otu[7649]. The next 160 bits of RS parity are now mapped to the otu, i.e., rsparity[0]...rsparity[159] $\rightarrow$ otu[7650]...otu[7809]. + +Having completed the first RS code, the next 7650 bits of odu are mapped to the otu, i.e., odu[7650]...odu[15299] $\rightarrow$ otu[7810]...otu[15459]. These 765 dectets are RS encoded, and the 160 bits of RS parity are inserted into the outgoing otu, i.e., rsparity[0]...rsparity[159] $\rightarrow$ otu[15460]...otu[15619]. + +This process is repeated for all 15 RS codes in the same manner. For the 16th and final code, there are $122368 - 15 \times 765 \times 10 = 7618$ bits of remaining odu. These bits are packed into 762 dectets. The final 2 bits, which are missing are 0 filled and packed into the last dectet. These 762 dectets are RS encoded with an RS(778,762) code. Again 160 bits of parity are added to the outgoing otu. Thus odu[114749]...odu[122367] $\rightarrow$ otu[117149]...otu[124767]. Note that the last 2 bits are 0 filled for the purpose of RS encoding; however, they are not actually transmitted into the outgoing otu. The 160 parity bits are added as follows: rsparity[0]...rsparity[159] $\rightarrow$ otu[124768]...otu[124927]. + +Having completed the RS outer code, the BCH inner code is now added to the otu. The 124928 otu bits are then mapped into 64 identical BCH codes of BCH(2047,1952) with $m = 11$ and $T = 8$ , the parent code is shown above. This requires the 124928 bits to be grouped into 64 partitions of 1952 bits. The BCH mapping is as follows: otu[0] is used as the first bit for BCH[0]. otu[1] is used as the first bit for BCH[1] repeatedly until otu[63] is used as the first bit for BCH[63]. Then otu[64] + +is used as the second bit for BCH[0]. otu[65] is used as the second bit for BCH[1]. This process is repeated until all 124928 otu bits are consumed by the 64 BCH codes. + +For each of the 64 BCH codes, the 1952 payload bits are encoded and 88 parity bits are added to the output. The 88 bits result from the product of $T = 8$ and $m = 11$ for the BCH codes. The BCH parity is added to the output otu as follows: + +BCH[0] bchparity[0] → otu[124928], BCH[1] bchparity[0] → otu[124929] repeatedly until BCH[63] bchparity[0] → otu[124992]. Then the next bit of each BCH code is added to the output otu, i.e., BCH[0] bchparity[1] → otu[124993]. This is repeated until all 64 BCH codes have exhausted their 88 parity bits. i.e., BCH[63] bchparity[87] → otu[130559] the last bit of the output otu frame. + +#### I.4.2.2 Reed-Solomon encoder + +The Primitive Binary Polynomial is as follows: + +$$p(x) = x^{10} + x^3 + 1$$ + +#### I.4.2.3 BCH encoder + +The Primitive Binary Polynomial is as follows: + +$$p(x) = x^{11} + x^2 + 1$$ + +### I.4.3 Error correction ability + +Error correction ability of this super FEC is shown in Table I.4 and in Figures I.13 and I.14. + +![Figure I.13/G.975.1 – Results: A log-log plot showing Decoded BER (Y-axis, 10^-15 to 10^-1) versus Channel BER (X-axis, 10^-1 to 10^-4). The plot compares EFEC simulation (blue triangles), EFEC measured (blue circles), G.709/Y.1331 FEC measured (red diamonds), and GFEC analysis data (solid blue line) and measured data (yellow diamonds). The EFEC curve shows a sharp drop in BER around Channel BER 10^-2.5, while the G.709/Y.1331 FEC curve shows a more gradual drop starting around Channel BER 10^-2.5.](982cedb5d39e222cf34bf53c92a7ee4d_img.jpg) + +The figure is a log-log plot of Decoded BER versus Channel BER. The Y-axis (Decoded BER) ranges from $10^{-15}$ to $10^{-1}$ . The X-axis (Channel BER) ranges from $10^{-1}$ to $10^{-4}$ . The legend indicates: + + +- EFEC simulation (blue triangle) +- EFEC measured (blue circle) +- G.709/Y.1331 FEC measured (red diamond) + + Two yellow callout boxes provide additional details: + + +- EFEC curve: Simulation data (triangle), Measured data (circle) +- GFEC curve: Analysis data (solid line), Measured data (diamond) + + The EFEC curve shows a sharp drop in BER around Channel BER $10^{-2.5}$ , reaching a floor around $10^{-13}$ . The G.709/Y.1331 FEC curve shows a more gradual drop starting around Channel BER $10^{-2.5}$ , reaching a floor around $10^{-15}$ at Channel BER $10^{-4}$ . + +Figure I.13/G.975.1 – Results: A log-log plot showing Decoded BER (Y-axis, 10^-15 to 10^-1) versus Channel BER (X-axis, 10^-1 to 10^-4). The plot compares EFEC simulation (blue triangles), EFEC measured (blue circles), G.709/Y.1331 FEC measured (red diamonds), and GFEC analysis data (solid blue line) and measured data (yellow diamonds). The EFEC curve shows a sharp drop in BER around Channel BER 10^-2.5, while the G.709/Y.1331 FEC curve shows a more gradual drop starting around Channel BER 10^-2.5. + +Figure I.13/G.975.1 – Results + +![Figure I.14/G.975.1 – Net coding gain. A log-linear plot showing Bit Error Rate (BER) on the y-axis (logarithmic scale from 1.00E-15 to 1.00E-02) versus Normalized OSNR (dB) on the x-axis (linear scale from 0 to 12). Two curves are shown: a blue curve labeled 'EFEC correction enabled' and a purple curve labeled 'FEC correction disabled'. The blue curve drops sharply to a BER of 1.00E-13 at approximately 1.5 dB OSNR. The purple curve drops more gradually, reaching a BER of 1.00E-13 at approximately 9.5 dB OSNR. A horizontal green double-headed arrow between these two points is labeled '8.5 dB', indicating the net coding gain.](bfb6d182d624680db577069bbc0b2a93_img.jpg) + +Figure I.14/G.975.1 – Net coding gain. A log-linear plot showing Bit Error Rate (BER) on the y-axis (logarithmic scale from 1.00E-15 to 1.00E-02) versus Normalized OSNR (dB) on the x-axis (linear scale from 0 to 12). Two curves are shown: a blue curve labeled 'EFEC correction enabled' and a purple curve labeled 'FEC correction disabled'. The blue curve drops sharply to a BER of 1.00E-13 at approximately 1.5 dB OSNR. The purple curve drops more gradually, reaching a BER of 1.00E-13 at approximately 9.5 dB OSNR. A horizontal green double-headed arrow between these two points is labeled '8.5 dB', indicating the net coding gain. + +Figure I.14/G.975.1 – Net coding gain + +Table I.4/G.975.1 – Summary for correction ability + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|-----------------------|------------|----------------------|------------------|--------------| +| $2.41 \times 10^{-3}$ | $10^{-9}$ | 6.31 | 6.59 | 9.0013 | +| $2.35 \times 10^{-3}$ | $10^{-10}$ | 6.83 | 7.11 | 9.0262 | +| $2.30 \times 10^{-3}$ | $10^{-11}$ | 7.30 | 7.58 | 9.0473 | +| $2.26 \times 10^{-3}$ | $10^{-12}$ | 7.63 | 7.91 | 9.0645 | +| $2.23 \times 10^{-3}$ | $10^{-13}$ | 8.03 | 8.31 | 9.0775 | +| $2.20 \times 10^{-3}$ | $10^{-14}$ | 8.34 | 8.62 | 9.0906 | +| $2.17 \times 10^{-3}$ | $10^{-15}$ | 8.67 | 8.95 | 9.1034 | + +### I.4.4 Redundancy ratio + +The redundancy ratio of the Interleaved RS(1023,1007)/BCH(2047,1952) Code is 7%, the same as the legacy RS FEC as defined in ITU-T Rec. G.975. + +### I.4.5 Latency + +The latency is implementation dependent. Current implementations have been proven to have low latency. + +### I.4.6 Property + +The code described provides excellent error correction capability over a broad range of operating conditions and channel error rates. The choice of the particular inner and outer codes results in good performance being achieved in a small number of iterations (one or two), and results in a shorter + +latency as compared to many similarly performing codes which require a higher number of iterations. The choice of code also ensures that no flaring in the performance curves will occur in the operating range of interest (i.e., for BERs less than $10^{-20}$ ). + +## I.5 Concatenated RS and product code super-FEC scheme + +### I.5.1 Overview + +This appendix describes a FEC code, which provides higher error correction capability than an RS(255,239) code, for exactly the same amount of overhead and which lends itself to soft decision decoding. Figure I.15 shows an overview of this Super-FEC scheme. This Super-FEC scheme uses a concatenated code consisting of a Reed-Solomon RS(1901,1855) outer code and an Extended Hamming (512,502) $\times$ (510,500) Product inner code. + +![Figure I.15/G.975.1 – Advanced-FEC scheme diagram. The diagram shows the flow of data through an RS encoder, a product encoder, a transmission line, a product decoder, and an RS decoder. Input: 244736 data bits (= 2 ODUk frames) + 124 bits padding. RS encoder: RS(1901,1855) x 12 interleaves. Output: 250932 data bits (= 12 x RS(1901,1855)) + 68 bits padding. Product encoder: (512,502) x (510,500) Extended hamming code. Output: 261120 data bits (= 2 OTUk frames). Transmission line. Product decoder: (512,502) x (510,500) Extended hamming code. RS decoder: RS(1901,1855) x 12 interleaves. n iterations.](eb5677b570ab2a3e9d8f5d35ca5b8a4d_img.jpg) + +The diagram illustrates the Advanced-FEC scheme. On the left, input data (244736 data bits, equivalent to 2 ODUk frames) and 124 bits of padding are fed into an RS encoder. The RS encoder consists of 12 interleaves of RS(1901,1855) codes. The output of the RS encoder is 250932 data bits (which is 12 times the output of a single RS(1901,1855) code) plus 68 bits of padding. This output is then fed into a Product encoder, which consists of 12 interleaves of (512,502) x (510,500) Extended Hamming codes. The output of the Product encoder is 261120 data bits (equivalent to 2 OTUk frames). This data is transmitted over a transmission line. On the receiver side, the data is first processed by a Product decoder, which consists of 12 interleaves of (512,502) x (510,500) Extended Hamming codes. The output of the Product decoder is then fed into an RS decoder, which consists of 12 interleaves of RS(1901,1855) codes. The RS decoder output is the final data. The diagram also indicates 'n iterations' for the Product decoder. + +Figure I.15/G.975.1 – Advanced-FEC scheme diagram. The diagram shows the flow of data through an RS encoder, a product encoder, a transmission line, a product decoder, and an RS decoder. Input: 244736 data bits (= 2 ODUk frames) + 124 bits padding. RS encoder: RS(1901,1855) x 12 interleaves. Output: 250932 data bits (= 12 x RS(1901,1855)) + 68 bits padding. Product encoder: (512,502) x (510,500) Extended hamming code. Output: 261120 data bits (= 2 OTUk frames). Transmission line. Product decoder: (512,502) x (510,500) Extended hamming code. RS decoder: RS(1901,1855) x 12 interleaves. n iterations. + +Figure I.15/G.975.1 – Advanced-FEC scheme + +### I.5.2 Super-FEC algorithm + +#### I.5.2.1 RS encoding + +The outer RS code used is RS(1901,1855), with the generator polynomial given by: + +$$G(z) = \prod_{i=0}^{45} (z - \alpha^{i+1001})$$ + +where $\alpha$ is a root of the binary primitive polynomial $x^{11} + x^2 + 1$ . + +Elements of $GF(2^{11})$ are represented over the polynomial basis. The transmission order of the bits in a symbol is most significant bit first. The transmission order of symbols in a codeword is most significant symbol first, with the first 1855 symbols containing data and the remaining 46 symbols parity. + +Twelve RS(1901,1855) codewords are interleaved, with the input payload data being distributed over these interleaves on a round-robin symbol-by-symbol basis. + +124 bits are zero padded, as follows: + +- 1) The least significant 3 bits of the last data symbol of the first interleave are zero padded. +- 2) The last data symbols of the remaining 11 interleaves are zero padded. + +The total number of input data bits, for the 12 RS codes, is 244736 ( $= 11 \times 12 \times 1855 - 124$ ). This is exactly the same as that for two ODU frames. + +#### I.5.2.2 Product code encoding + +![Figure I.16/G.975.1 – Product code matrix. The diagram shows a grid of bits with columns numbered 511 down to 0 at the top. Rows are numbered 509 down to 0 on the right. The bottom rows are labeled hhc9, hhc3, hhc2, hhc1, hhc0, and hp. The rightmost columns are labeled vhc9, vhc3, vhc2, vhc1, vhc0, and vp. The grid is filled with horizontal and vertical hatching for check and parity bits, and white space for data. Arrows on the right indicate row-by-row transmission. A legend at the bottom defines the hatching patterns: horizontal hatching for 'Horizontal hamming check & parity', vertical hatching for 'Vertical hamming check & parity', and white for 'Data'. The label 'G.975.1_FI.16' is in the bottom right.](2bacc162a73d75c43a7f90715832bd13_img.jpg) + +Figure I.16/G.975.1 – Product code matrix. The diagram shows a grid of bits with columns numbered 511 down to 0 at the top. Rows are numbered 509 down to 0 on the right. The bottom rows are labeled hhc9, hhc3, hhc2, hhc1, hhc0, and hp. The rightmost columns are labeled vhc9, vhc3, vhc2, vhc1, vhc0, and vp. The grid is filled with horizontal and vertical hatching for check and parity bits, and white space for data. Arrows on the right indicate row-by-row transmission. A legend at the bottom defines the hatching patterns: horizontal hatching for 'Horizontal hamming check & parity', vertical hatching for 'Vertical hamming check & parity', and white for 'Data'. The label 'G.975.1\_FI.16' is in the bottom right. + +**Figure I.16/G.975.1 – Product code matrix** + +In encoding a Product Code row, the Hamming Check bits are arranged as follows: for the purpose of explanation, we order the bits in each row from 511 down to 0, to designate the "position number" of each bit. Positions with power of 2 position number are occupied by Hamming check bits. Position 0 is occupied by the parity bit. The remaining 502 row positions are used for data. + +The Hamming check bits are calculated by bit wise modulo-2 addition of the position numbers of all data bits with value "1". Hamming check bit 0 is located in position 1, Hamming check bit 1 in position 2, Hamming check bit 2 in position 4, etc. with the remaining Hamming check bits in positions 8, 16, 32, 64, 128 and 256. + +Finally to form the parity bit, calculate the modulo-2 sum of all 511 Hamming codeword bits and assign the result to position 0. + +The same principle applies to the coding of columns, but the code is shortened by removal of the bits with position numbers 511 and 510. + +The resulting Product Code is therefore of length $512 \times 510 = 261120$ encoded bits, which is exactly the same as two OTU frames. + +After encoding the data as described, the Product Code matrix is transmitted on a row-by-row basis. The first bit to be transmitted is the bit from row 509 and column 511. + +### I.5.3 Error correction ability + +The error correction ability of this Super-FEC code will depend upon the method of inner Product Code decoding (for example, upon the number of bits of quantization used by a soft decision decoder). Table I.5 shows the error correction ability of a decoder using two bit (four levels) receiver quantization and performing 8 SISO iterations1. Table I.6 shows the error correction ability of the same decoder when used with a single bit (two levels) quantizer1. + +1 The coding gain values given are obtained by simulation and analysis. + +**Table I.5/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|------------------|-------------------|-----------------------------|-------------------------|---------------------| +| 4.7E-03 | 1.00E-09 | 7.0 | 7.3 | 8.3 | +| 4.7E-03 | 1.00E-10 | 7.5 | 7.8 | 8.3 | +| 4.7E-03 | 1.00E-11 | 7.9 | 8.2 | 8.3 | +| 4.6E-03 | 1.00E-12 | 8.4 | 8.6 | 8.3 | +| 4.6E-03 | 1.00E-13 | 8.7 | 9.0 | 8.3 | +| 4.6E-03 | 1.00E-14 | 9.1 | 9.3 | 8.3 | +| 4.5E-03 | 1.00E-15 | 9.4 | 9.7 | 8.3 | + +**Table I.6/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|------------------|-------------------|-----------------------------|-------------------------|---------------------| +| 2.0E-03 | 1.00E-09 | 6.1 | 6.4 | 9.2 | +| 2.0E-03 | 1.00E-10 | 6.6 | 6.9 | 9.2 | +| 2.0E-03 | 1.00E-11 | 7.0 | 7.3 | 9.2 | +| 1.9E-03 | 1.00E-12 | 7.5 | 7.7 | 9.2 | +| 1.9E-03 | 1.00E-13 | 7.8 | 8.1 | 9.2 | +| 1.9E-03 | 1.00E-14 | 8.2 | 8.4 | 9.2 | +| 1.9E-03 | 1.00E-15 | 8.5 | 8.8 | 9.2 | + +The burst error correction capability of this Super-FEC code will be dependent upon the method of inner Product Code decoding, but will be at least 1024 bits. + +### **I.5.4 Redundancy ratio** + +The redundancy ratio of this Super-FEC code is 6.69%, and is exactly the same as that of RS(255,239) code. + +### **I.5.5 Latency** + +The latency associated with the encoding and decoding of this Super-FEC code is implementation dependent. + +### **I.5.6 Properties** + +Iterative decoding can be applied to product codes. The Extended Hamming code is also amenable to soft decision decoding for enhanced coding gain. The proposed product code is thus suitable for soft-in-soft-out (SISO) iterative decoding. Further, the Extended Hamming code lends itself to soft decision decoding with modest decoding complexity (i.e., modest power dissipation). Soft decision receivers use 2 or more bit quantization, the number of bits used being vendor specific. + +## **I.6 LDPC super FEC code** + +### **I.6.1 Overview** + +The code described here after is a systematic binary low-density parity-check (LDPC) code of length 32640, with 30592 information-carrying bits, identical to the length and dimension of the standard interleaved RS(255,239) code. This LDPC code is suitable for implementation in current chip technologies for 10G and 40G optical systems and has been shown to provide a significantly higher coding gain than the standardized RS code. The extra gain can for instance be used to + +improve the line parameters, the maximum span length, relax the optical component and line fibre specifications, or improve the overall quality of communication against degraded operation conditions. + +### I.6.2 Super FEC algorithm + +The described FEC code is a systematic binary low-density parity-check (LDPC) code of length 32640, which is specified by a binary two-dimensional matrix $M$ with 112 rows and 293 columns, the elements of which are indexed by the coordinates $(a,b)$ , where $0 \leq a \leq 111$ and $0 \leq b \leq 292$ as illustrated in Figure I.17. This matrix, which contains a total of 32816 bits, is filled with 30592 information-carrying bits corresponding to a standard $239 \times 16 \times 8$ FEC frame payload as follows. The $j$ th information bit, where $1 \leq j \leq 30592$ , is located at coordinate $(r, 293 r + 292 - q)$ in $M$ , where $q = j + 172$ and $r = \lfloor q/293 \rfloor$ . The 173 entries $(0, 292 - d)$ , where $0 \leq d \leq 172$ are set to 'zero' and are not transmitted. It follows that the 30592 information-carrying bits are located in the first 105 rows, row 0 up to row 104 ( $105 \times 293 - 173 = 30592$ bits). A total of 2051 parity-check equations determine the values of the last seven rows of $M$ ( $7 \times 293 = 2051$ bits) in the following manner. Consider the coordinates of the matrix $M$ to form a grid of $112 \times 293$ points. A non-horizontal line through coordinate $(0,c)$ with slope $s_i$ , where $0 \leq c \leq 292$ and $0 \leq s_i \leq 292$ , is defined as the set of coordinates $\{(a,b) \mid 0 \leq a \leq 111, b = (as_i + c) \bmod 293\}$ , i.e., every non-horizontal line consists of exactly 112 points, seven of which are parity check positions. The code is now defined by selecting seven different slopes $s_1, \dots, s_7$ , which, in turn, specify seven sets of 293 parallel lines through each point $(0,c)$ , where $0 \leq c \leq 292$ . This implies that every coordinate $(a,b)$ of $M$ , where $0 \leq a \leq 111$ and $0 \leq b \leq 292$ is an element of seven lines of 112 elements each that intersect at coordinate $(a,b)$ . All codewords of the LDPC code satisfy the condition that the parity check sum of the 112 bits specified by each of the $(7 \times 293) = 2051$ lines is equal to 'zero' (using binary addition modulo 2). This completely defines the check bit values that are located in the last seven rows of $M$ . The system of 2051 parity-check equations can be solved with $2051 - 6 = 2045$ parity-check bits and therefore there are 6 redundant check bits, which are chosen to be at positions $(v, 292)$ , where $105 \leq v \leq 110$ , as illustrated in Figure I.17. These 6 positions are fixed to 'zero' and are not transmitted, i.e., only 2045 bits out of the 2048 available check bits per frame are used and transmitted. The mapping structure of the proposed systematic LDPC code of length 32640 with 30592 information-carrying bits and 2048 check bits is also illustrated in Figure I.17. The LDPC codewords have a format that is identical to the interleaved standard RS codes. The payload occupies the first $239 \times 16 \times 8$ bits, followed by three 'zeros' and the 2045 check bits. The check bit sequence corresponds to the sequence of elements $(105,291), \dots, (105,0), (106,291), \dots, (106,0), (107,291), \dots, (107,0), (108,291), \dots, (108,0), (109,291), \dots, (109,0), (110,291), \dots, (110,0), (111,292), \dots, (111,0)$ , i.e., a concatenation of the $(6 \times 292)$ -bit rows 105 up to 110, followed by the 293 check bits of row 111. As previously indicated, the left-most elements $(v, 292)$ , where $105 \leq v \leq 110$ , corresponding to the redundant check bits that have been fixed to 'zero', are not transmitted and will be regenerated automatically in the decoder. + +![Mapping structure for the LDPC code diagram showing frame structure and internal bit numbering.](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +The diagram illustrates the mapping structure for the LDPC code. At the top, a horizontal bar represents the 'Frame structure' from 'Byte #1' to 'Byte #4080'. Below this, a detailed view of the bit mapping is shown. The vertical axis represents 'Internal row number' from 0 to 292. The horizontal axis represents 'Internal bit numbering' from 0 to 292. The mapping is organized into several sections: + + +- Top section (Rows 111 to 292):** Contains 'Check bits' (hatched pattern). Bit #3840 is at row 111, and bit #3824 is at row 104. An arrow points to a small section at the top left labeled '3 unused bits (set to "0")'. +- Middle section (Rows 1 to 104):** Contains 'Payload' (white). Bit #16 is at row 1, and bit #12 is at row 1. An arrow points to a section labeled '6 redundant code bits (not transmitted)'. +- Bottom section (Rows 0 to 1):** Contains 'Zeros (not transmitted)' (dotted pattern). An arrow points to this section labeled '173 bits are set to "0"'. Bit #1 is at row 0. +- Transmission order:** Indicated by arrows showing the sequence of bits from left to right, then jumping to the next row. +- Legend:** + - Zeros (not transmitted): Dotted pattern + - Check bits: Hatched pattern + - OH bytes: Diagonal line pattern + - Payload: White + - Unused/not transmitted: Solid black + +Mapping structure for the LDPC code diagram showing frame structure and internal bit numbering. + +**Figure I.17/G.975.1 – Mapping structure for the LDPC code** + +The proposed code can be implemented efficiently with low power dissipation, which is of particular importance for 40G applications. Furthermore, there are powerful algorithms known for this code to exploit soft information, should this become available. + +### I.6.3 Error correction ability + +The performance of the LDPC code is shown in Figures I.18 and I.19. The graphs have been obtained using a series of combined simulation and analysis techniques to accurately estimate the error performance for high and low input bit error rates. The actual measurements of an LDPC code implementation are in agreement with the simulations and confirm the accuracy of the estimation methods. + +![Figure I.18/G.975.1: Output BER as a function of the input BER for the LDPC code and for comparison with the G.975 standard RS FEC code. The graph shows three curves: G.975 standard FEC (dashed line), LDPC simulation/analysis (solid line), and LDPC measured (crosses). The x-axis is Input BER from 0 to 4 x 10^-3, and the y-axis is Output BER from 10^-16 to 10^-2. The LDPC curves show a sharp drop in output BER starting around an input BER of 10^-3, while the G.975 standard FEC curve shows a more gradual decrease.](d68ecc44f3cfaed866a846f9fa4bdf38_img.jpg) + +Figure I.18/G.975.1: Output BER as a function of the input BER for the LDPC code and for comparison with the G.975 standard RS FEC code. The graph shows three curves: G.975 standard FEC (dashed line), LDPC simulation/analysis (solid line), and LDPC measured (crosses). The x-axis is Input BER from 0 to 4 x 10^-3, and the y-axis is Output BER from 10^-16 to 10^-2. The LDPC curves show a sharp drop in output BER starting around an input BER of 10^-3, while the G.975 standard FEC curve shows a more gradual decrease. + +Figure I.18/G.975.1 – Output BER as a function of the input BER for the LDPC code and for comparison with the G.975 standard RS FEC code + +![Figure I.19/G.975.1: Output BER as a function of the electrical SNR for the LDPC code and the existing standard RS FEC code. The graph shows four curves: FEC uncoded (dash-dot line), G.975 standard FEC (dashed line), LDPC simulation/analysis (solid line), and LDPC measured (crosses). The x-axis is Electrical SNR [dB] from 5 to 16, and the y-axis is Output BER from 10^-16 to 10^-2. The LDPC curves show a sharp drop in output BER starting around an electrical SNR of 6 dB, while the G.975 standard FEC curve shows a more gradual decrease. Annotations indicate that at an output BER of 10^-16, the LDPC code requires an electrical SNR of 2.0 dB, while the G.975 standard FEC code requires 6.3 dB.](a844248c1fa0a79f187fc9aa111182f7_img.jpg) + +Figure I.19/G.975.1: Output BER as a function of the electrical SNR for the LDPC code and the existing standard RS FEC code. The graph shows four curves: FEC uncoded (dash-dot line), G.975 standard FEC (dashed line), LDPC simulation/analysis (solid line), and LDPC measured (crosses). The x-axis is Electrical SNR [dB] from 5 to 16, and the y-axis is Output BER from 10^-16 to 10^-2. The LDPC curves show a sharp drop in output BER starting around an electrical SNR of 6 dB, while the G.975 standard FEC curve shows a more gradual decrease. Annotations indicate that at an output BER of 10^-16, the LDPC code requires an electrical SNR of 2.0 dB, while the G.975 standard FEC code requires 6.3 dB. + +Figure I.19/G.975.1 – Output BER as a function of the electrical SNR for the LDPC code and the existing standard RS FEC code + +**Table I.7/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|-----------------------|------------|----------------------|------------------|--------------| +| $1.61 \times 10^{-3}$ | $10^{-9}$ | 5.90 | 6.18 | 9.38 | +| $1.51 \times 10^{-3}$ | $10^{-10}$ | 6.35 | 6.63 | 9.44 | +| $1.42 \times 10^{-3}$ | $10^{-11}$ | 6.75 | 7.03 | 9.50 | +| $1.33 \times 10^{-3}$ | $10^{-12}$ | 7.10 | 7.39 | 9.56 | +| $1.25 \times 10^{-3}$ | $10^{-13}$ | 7.43 | 7.72 | 9.61 | +| $1.18 \times 10^{-3}$ | $10^{-14}$ | 7.73 | 8.02 | 9.66 | +| $1.12 \times 10^{-3}$ | $10^{-15}$ | 8.02 | 8.30 | 9.70 | + +### I.6.4 Redundancy ratio + +The redundancy ratio of the LDPC strong FEC is with 7% the same as the legacy RS FEC as defined in ITU-T Rec. G.975 and given by the relation of 32640 total transmitted bits, with 30592 information bits. + +### I.6.5 Latency + +The decoding latency of the described LDPC code can be implemented with low latency, as shown in Table I.8 similar to the standard RS code. + +**Table I.8/G.975.1 – Decoding latency of the LDPC code** + +| Gbit/s | Latency [ $\mu\text{s}$ ] | +|--------|---------------------------| +| 42.7 | $< 3$ | +| 10.7 | $\sim 3$ | +| 2.7 | $\sim 12$ | + +### I.6.6 Property + +The described code is a systematic binary low-density parity-check (LDPC) code of length 32640, with 30592 information-carrying bits, identical to the length and dimension of the standard RS(255,239) code, as specified in ITU-T Recs G.709/Y.1331 and G.975. This LDPC code is suitable for implementation in current chip technologies for 10G and 40G optical systems offering low latency and feasibility of low power consumption in case of 40G implementation showing a significantly higher coding gain than the standardized RS code. + +## I.7 Two orthogonally concatenated BCH super FEC code + +### I.7.1 Overview + +This FEC scheme described hereafter will contain three parameterizations of the same scheme of two orthogonally interleaved block codes (BCH). The constructed code should be decoded iteratively, to achieve the expected performance. For practical reasons, hard decision error correcting algorithms have to be implemented. The first option will apply for the special case of G.709/Y.1331 compliant framing (7% overhead), while the two others will deliver a high performance option with 11% and 25% FEC overhead. + +The performance of low overhead FEC algorithms, especially at low output error rates, heavily depends on the codeword length. Though in general, ITU-T Rec. G.975 allows any interleave and thus any frame size, especially in the case of frames compliant to ITU-T Rec. G.709/Y.1331 the frame length (130560 bits) imposes a major problem, if the codeword length of the used FEC algorithm and the frame size are identical. + +Thus, in opposite to other concepts, this scheme decouples the transmission framing from the structure used for FEC coding. Both are converted into each other using dedicated remapping schemes (see Figure I.20). This scheme expects at the encoder incoming data to be formatted according to ITU-T Rec. G.975 (incl. scrambling) leaving the FEC overhead area void. This also allows using the same basic code system to be used for 25%, 11% and 7% overhead with remarkable performance in all cases. + +![Diagram illustrating the basic remapping scheme for FEC. It shows the conversion between a G.975 compliant frame format and an Intermediate FEC format. The G.975 format has a void area for FEC overhead. The Intermediate FEC format includes FEC redundancy. Mapping and Inv. Mapping blocks facilitate the conversion between the two formats.](85e2327652d513a7fee8fdbf97ad06f1_img.jpg) + +The diagram illustrates the basic remapping scheme. At the top, two boxes represent the 'G.975 compliant frame format'. Each box contains a sequence of data blocks with two shaded areas representing the FEC overhead. Below the left box is a 'Mapping' block, and below the right box is an 'Inv. Mapping' block. Both blocks point to a central box labeled 'Intermediate FEC format'. This box contains a sequence of data blocks with shaded areas representing 'FEC redundancy'. A legend on the right shows a shaded rectangle labeled 'FEC redundancy'. The diagram is labeled 'G.975.1\_FI.20' in the bottom right corner. + +Diagram illustrating the basic remapping scheme for FEC. It shows the conversion between a G.975 compliant frame format and an Intermediate FEC format. The G.975 format has a void area for FEC overhead. The Intermediate FEC format includes FEC redundancy. Mapping and Inv. Mapping blocks facilitate the conversion between the two formats. + +**Figure I.20/G.975.1 – Basic remapping scheme** + +In the following subclauses, the underlying code system, the intermediate FEC format and the mapping into G.975 compliant frames are described. + +### I.7.2 Super FEC algorithm + +This clause describes first the construction of the underlying code system of two orthogonally interleaved BCH codes. This is followed by the definition of the mapping procedure used to apply this coding scheme to the transmission stream. + +#### I.7.2.1 Basic code system + +The underlying code system consists of two orthogonally concatenated BCH code classes called "row encoding" and "column encoding". The corresponding code parameters are shown in Table I.9. + +**Table I.9/G.975.1 – Basic code construction** + +| Row encoding | | +|--------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Generator polynomials for $t_r$ error correction code: | $G(x) = \prod_{i=1}^{2t_r-1} G_{2i-1}(x)$ $G_1(x) = x^{10} + x^3 + 1$ $G_3(x) = x^{10} + x^3 + x^2 + x + 1$ $G_5(x) = x^{10} + x^8 + x^3 + x^2 + 1$ $G_7(x) = x^{10} + x^9 + x^8 + x^7 + x^6 + x^5 + x^4 + x^3 + 1$ $G_9(x) = x^{10} + x^7 + x^5 + x^3 + x^2 + x + 1$ $G_{11}(x) = x^{10} + x^5 + x^4 + x^2 + 1$ $G_{13}(x) = x^{10} + x^6 + x^5 + x^3 + x^2 + x + 1$ $G_{15}(x) = x^{10} + x^8 + x^7 + x^5 + x^3 + x + 1$ $G_{17}(x) = x^{10} + x^9 + x^8 + x^6 + x^3 + x^2 + 1$ $G_{19}(x) = x^{10} + x^8 + x^7 + x^6 + x^5 + x^4 + x^3 + x + 1$ $G_{21}(x) = x^{10} + x^9 + x^8 + x^7 + x^6 + x^5 + x^3 + x + 1$ | +| Column encoding | | +| Generator polynomials for $t_c$ error correction code: | $G(x) = \prod_{i=1}^{2t_c-1} G_{2i-1}(x)$ $G_1(x) = x^9 + x^4 + 1$ $G_3(x) = x^9 + x^6 + x^4 + x^3 + 1$ $G_5(x) = x^9 + x^8 + x^5 + x^4 + 1$ $G_7(x) = x^9 + x^7 + x^4 + x^3 + 1$ | + +Codewords are processed in their natural order starting with the highest exponent, when considered as polynomials. When shortening the codeword length, the codeword is padded with zeros starting at the highest exponent. + +#### **I.7.2.2 Intermediate FEC format** + +Conception wise, the basic BCH codewords are used to construct a matrix of $x \times y$ bits (see left hand Figure I.21). Each row consists of a single row codeword of $x$ bits. Each column represents a column codeword of $y$ bits. Two arbitrary row and column codewords intersect in at most one bit. + +![Figure I.21/G.975.1 – Concept of orthogonally interleaved codewords as matrix or streaming structure. The left diagram shows a matrix of width x and height y. The main area is 'Payload' with dimensions (x - 10*t_r) by (y - 9*t_c). To the right is 'Row parity' and below is 'Column parity'. A small square at the bottom right of the payload is labeled 'One bit' and 'Shared by a row and column codeword parity'. The right diagram shows a streaming structure where column codewords (C_1,n, C_2,n, etc.) are diagonally interleaved across row codewords (R_1,n, R_2,n, etc.). The structure repeats for index n+1. Label: G.975.1_FI.21.](f57c7b37d7a05a99618104f390089f03_img.jpg) + +Figure I.21/G.975.1 – Concept of orthogonally interleaved codewords as matrix or streaming structure. The left diagram shows a matrix of width x and height y. The main area is 'Payload' with dimensions (x - 10\*t\_r) by (y - 9\*t\_c). To the right is 'Row parity' and below is 'Column parity'. A small square at the bottom right of the payload is labeled 'One bit' and 'Shared by a row and column codeword parity'. The right diagram shows a streaming structure where column codewords (C\_1,n, C\_2,n, etc.) are diagonally interleaved across row codewords (R\_1,n, R\_2,n, etc.). The structure repeats for index n+1. Label: G.975.1\_FI.21. + +**Figure I.21/G.975.1 – Concept of orthogonally interleaved codewords as matrix or streaming structure** + +The lower right hand quadrant (R/C) is shared between the two code classes. It is filled with parity of column codewords computed over the row parity. Being linear algebraic codes, this is identical to the parity of row codewords computed over the column codeword parity. Thus, in this matrix representation, it would only be needed to be computed and transmitted once. The size of this matrix depends on the precise code parameters. In the described configurations, it is in the range of ~500 kbit/s. + +To ease implementation, this matrix structure is reformatted into a streaming structure, which is shown in the right hand part of Figure I.21. It shows that the column words are now no longer aligned against the matrix boundaries, but are shifted across more than two matrices in case $y' < y$ . Here the modified matrix has a fixed logical width of 32 bits ( $y' = 32$ ). + +In Figure I.22, the allocation of the row codewords ( $R_{i,m}$ ) into the stream of modified matrices is shown. Thirty-two independent codewords of length X are mapped to a set of 32 adjacent bits, so they are bit wise interleaved. They form a codeword group $R_m$ with all 32 codewords aligned to the same set of 32 adjacent bits. + +![Figure I.22/G.975.1 – Row code allocation. The diagram shows a horizontal stream of data. A section labeled R_m has a width of 'x bit', further divided into 'x - 10*t_r bit' and 'Row parity'. The height is '32 bits'. It shows rows labeled r_{1,m}, r_{2,m}, up to r_{32,m}. To the right, the next section R_{m+1} begins with r_{1,m-1}, r_{2,m-2}, up to r_{32,m+1}. A vertical shaded bar marks a boundary. On the left, two downward arrows indicate 'Processing order'. Label: G.975.1_FI.22.](b2f5606b9c7184c1c6070a290080a3e3_img.jpg) + +Figure I.22/G.975.1 – Row code allocation. The diagram shows a horizontal stream of data. A section labeled R\_m has a width of 'x bit', further divided into 'x - 10\*t\_r bit' and 'Row parity'. The height is '32 bits'. It shows rows labeled r\_{1,m}, r\_{2,m}, up to r\_{32,m}. To the right, the next section R\_{m+1} begins with r\_{1,m-1}, r\_{2,m-2}, up to r\_{32,m+1}. A vertical shaded bar marks a boundary. On the left, two downward arrows indicate 'Processing order'. Label: G.975.1\_FI.22. + +**Figure I.22/G.975.1 – Row code allocation** + +The column codewords are mapped vertically over this structure as shown in Figure I.23. + +![Figure I.23/G.975.1 – General mapping of column codewords over the data stream. The diagram shows a data stream structure with row codeword groups R_m and R_{m+1}. Column codeword groups C_{j,n} and C_{j-1,n} are mapped vertically. A 32-bit column height is indicated. The shift between groups is labeled ΔPHI. A legend indicates 'Column parity' with a gray box. The diagram is labeled G.975.1_FI.23.](7f5df81190b8dc50dad2604562ae0715_img.jpg) + +The diagram illustrates the mapping of column codewords over a data stream. It shows two row codeword groups, $R_m$ and $R_{m+1}$ , separated by a dashed line. Within $R_m$ , there are column codeword groups $C_{j,n}$ and $C_{j-1,n}$ . Each column codeword group consists of four adjacent columns, labeled $C_{1,j,n}$ , $C_{2,j,n}$ , $C_{3,j,n}$ , and $C_{4,j,n}$ . A 32-bit column height is indicated by a vertical double-headed arrow. The shift between the start of $C_{j,n}$ and $C_{j-1,n}$ is labeled $\Delta PHI$ . Below $R_m$ , the start of $R_{m+1}$ is shown, with column codeword groups $C_{1,j,n+1}$ , $C_{2,j,n+1}$ , $C_{3,j,n+1}$ , and $C_{4,j,n+1}$ . A legend indicates 'Column parity' with a gray box. The diagram is labeled G.975.1\_FI.23. + +Figure I.23/G.975.1 – General mapping of column codewords over the data stream. The diagram shows a data stream structure with row codeword groups R\_m and R\_{m+1}. Column codeword groups C\_{j,n} and C\_{j-1,n} are mapped vertically. A 32-bit column height is indicated. The shift between groups is labeled ΔPHI. A legend indicates 'Column parity' with a gray box. The diagram is labeled G.975.1\_FI.23. + +**Figure I.23/G.975.1 – General mapping of column codewords over the data stream** + +Each 32-bit column is either member of a single column codeword $c_{a,b,d}$ ( $a$ : index within a column group, $b$ : column group index, $d$ : time sequential index) or, in case of a codeword boundary within a 32-bit column, of the two column codewords $c_{a,b,d}$ and $c_{a,b,d+1}$ . Four adjacent columns form a column group ( $C_{b,d}$ ). Each codeword of this group starts with the same codeword bit index $PHI_{b,d}$ in row one. Thus the codeword boundaries of all column codewords of a group are aligned to the same row index. The following codeword group (either $C_{b+1,d}$ or $C_{1,d+1}$ ) has an allocation shifted by $\Delta PHI$ bits ( $PHI_{1,d+1}$ , $PHI_{b+1,d} = (PHI_{b,d} + \Delta PHI) \bmod y$ ). A group is never spread over two row codeword groups ( $R_{i,m}$ , $R_{i,m+1}$ ). Thus, the row codeword length must be a multiple of 4. The column code bit index is incremented by $d$ for each consecutive group. A total of $l$ of such column groups exist ( $0 < b \leq l$ ; $4 \times l \geq x$ ). + +The resulting column codeword mapping is unrelated to the row codeword allocation except that a column codeword group never spans over two adjacent row codeword groups ( $R_{i,m}$ , $R_{i,m+1}$ ). Thus, it may happen that certain column codeword groups want to place their redundancy in the area of row code redundancy of row codeword group $R_m$ . This corresponds to the collision situation in the quadrant R/C of the matrix representation shown in Figure I.21. As the mapping is no longer algebraic, this has to be resolved by separate transmission of the column code parity. To reach this, the set of $n$ column codeword groups $C_{j(i),d}$ ( $j(i) < j(i + 1)$ , $0 < j(i) \leq l$ , $0 < i \leq n$ ), which would produce this collision, are removed from the sequence of column codeword groups generated by shifting the column codeword boundaries by $\Delta PHI$ . The removed column codeword groups are reinserted at the beginning of the next row codeword group $R_{m+1}$ in the order they were removed. In Figure I.24, the example of four column codeword groups swapped is shown. + +![Diagram illustrating the shifting of four column codeword groups. It shows a horizontal sequence of codewords with labels R_m and R_{m+1} at the top. A 'Row redundancy' section is highlighted. Below the main sequence, four column codeword groups are shown with labels C_{j(1),d}, C_{j(2),d}, C_{j(3),d}, C_{j(4),d} and C_{j(1),d+1}, C_{j(2),d+1}, C_{j(3),d+1}, C_{j(4),d+1}. Dashed arrows indicate the shifting of these groups. A legend at the bottom left shows a hatched box labeled 'Colliding row/Column parity'. The diagram is labeled G.975.1_FI.24.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +Diagram illustrating the shifting of four column codeword groups. It shows a horizontal sequence of codewords with labels R\_m and R\_{m+1} at the top. A 'Row redundancy' section is highlighted. Below the main sequence, four column codeword groups are shown with labels C\_{j(1),d}, C\_{j(2),d}, C\_{j(3),d}, C\_{j(4),d} and C\_{j(1),d+1}, C\_{j(2),d+1}, C\_{j(3),d+1}, C\_{j(4),d+1}. Dashed arrows indicate the shifting of these groups. A legend at the bottom left shows a hatched box labeled 'Colliding row/Column parity'. The diagram is labeled G.975.1\_FI.24. + +**Figure I.24/G.975.1 – Example of shifting four column codeword groups** + +After reinsertion of the removed column codeword groups, the codeword alignment is continued in accordance with the unmodified original sequence. + +Being a non-algebraic structure, it is further required to define the correct order of encoding. Here, first the column codeword coding is applied to the data stream, which is then followed by the row encoding. + +#### I.7.2.3 Mapping from G.975 compliant framing into internal representation + +For all overhead rates, the same basic G.975 compliant framing structure is used as shown in Figure I.25. + +![Diagram of the OTU2(V) frame structure. It shows four rows (Row 1, Row 2, Row 3, Row 4) concatenated to form the frame. Each row has a length of 'a' bits, with 'b' bits used for payload and management overhead, and the remaining (a-b) bits for FEC redundancy. The overhead section includes FAS, Mgmt. OH, and Mgmt. OH. The FEC redundancy section is labeled 'FEC redundancy'. The diagram is labeled G.975.1_FI.25.](b6ad8b32179842fca5ad086cf22b03eb_img.jpg) + +Diagram of the OTU2(V) frame structure. It shows four rows (Row 1, Row 2, Row 3, Row 4) concatenated to form the frame. Each row has a length of 'a' bits, with 'b' bits used for payload and management overhead, and the remaining (a-b) bits for FEC redundancy. The overhead section includes FAS, Mgmt. OH, and Mgmt. OH. The FEC redundancy section is labeled 'FEC redundancy'. The diagram is labeled G.975.1\_FI.25. + +**Figure I.25/G.975.1 – Used ITU-T Rec. G.975 compliant framing** + +It consists of 128 1-bit wide rows. Each row has a length of $a$ bits, of which $b$ bits are used as payload and management overhead and $(a-b)$ bits as FEC redundancy space. An OTU2(V) frame is built by concatenating four of the described frames. Each frame represents a single row of the OTU2(V) framing. The exact parameterization is shown in Table I.10. + +**Table I.10/G.975.1 – Parameterization of the transmitted framing** + +| | a | b | Code rate $D_f$ | +|---------------------------------------------------------------|------------|------------|-----------------| +| ITU-T G.709/Y.1331 compliant OTU k framing | 32640 bits | 30592 bits | 239/255 | +| ITU-T G.709/Y.1331 compliant OTU kV framing (11% mode) | 33536 bits | 30592 bits | 239/262 | +| ITU-T G.709/Y.1331 compliant OTU kV framing (25% mode) | 38016 bits | 30592 bits | 239/297 | + +The frame representing the fourth OTU2(v) row also contains a 32-bit wide field at the beginning of the FEC redundancy portion used to synchronize the following mapping procedure. + +##### **I.7.2.3.1 Mapping procedure** + +The mapping process consists of two functions. First the G.975 compliant frame is disassembling into the payload information (incl. OTU*k*(V) management overhead) and FEC redundancy bits. Both are written into two separate FIFO stores in the order received (see Figure I.26) except for the MSync pattern, which is discarded from the data stream. + +![Figure I.26/G.975.1 – Basic reformatting flow. A block diagram showing the flow from G.975 framing to Disassembly, then to two parallel FIFOs (Payload FIFO and Redundancy FIFO), then to Assembly, then to Internal framing, and finally to FEC processing. A '0' is shown entering the Assembly block from the Payload FIFO. The output of the Assembly block is labeled '1'.](0b3d9fe35da3ee0c88f1420bb9ed7a03_img.jpg) + +Figure I.26/G.975.1 – Basic reformatting flow. A block diagram showing the flow from G.975 framing to Disassembly, then to two parallel FIFOs (Payload FIFO and Redundancy FIFO), then to Assembly, then to Internal framing, and finally to FEC processing. A '0' is shown entering the Assembly block from the Payload FIFO. The output of the Assembly block is labeled '1'. + +G.975.1\_FI.26 + +**Figure I.26/G.975.1 – Basic reformatting flow** + +In a second step, data is read out of the FIFO stores to form the internal framing. Of each column codeword group, the first row bits of each codeword are filled in the sequential order. Then the next row is filled. After completion of a column codeword group, the next group is assembled. This process is shown in Figure I.27. The numbers at the single bit locations represent the time order in which they are assembled. + +![Figure I.27/G.975.1 – Basic mapping to internal framing. A diagram showing a grid of bits. The vertical axis is labeled 'Processing order' and '32 bits'. The horizontal axis is labeled 'Single bit' and 'Cj,n' and 'Cj+1,n'. The grid shows rows 1, 2, 31, and 32. The first four columns are labeled c1,j,n, c2,j,n, c3,j,n, c4,j,n. The bits are numbered 1 through 132. The first row contains bits 1, 2, 3, 4, 129, 130, 131, 132. The second row contains bits 5, 6, 7, 8. The 31st row contains bits 121, 122, 123, 124. The 32nd row contains bits 125, 126, 127, 128. Arrows indicate the processing order from top-left to bottom-right, then jumping to the next column group.](ccfd5ed8d9795009e923e2a0cacbcd6e_img.jpg) + +Figure I.27/G.975.1 – Basic mapping to internal framing. A diagram showing a grid of bits. The vertical axis is labeled 'Processing order' and '32 bits'. The horizontal axis is labeled 'Single bit' and 'Cj,n' and 'Cj+1,n'. The grid shows rows 1, 2, 31, and 32. The first four columns are labeled c1,j,n, c2,j,n, c3,j,n, c4,j,n. The bits are numbered 1 through 132. The first row contains bits 1, 2, 3, 4, 129, 130, 131, 132. The second row contains bits 5, 6, 7, 8. The 31st row contains bits 121, 122, 123, 124. The 32nd row contains bits 125, 126, 127, 128. Arrows indicate the processing order from top-left to bottom-right, then jumping to the next column group. + +G.975.1\_FI.27 + +**Figure I.27/G.975.1 – Basic mapping to internal framing** + +For the 25% OH mode, one column codeword group ( $C_{k,n}$ ) is filled with row parity by half (see Figure I.28). For this group, the assembly order is modified that each column codeword is filled completely before the next is assembled. + +![Figure I.28/G.975.1 – Mapping for the 25% mode. The diagram shows a horizontal bit stream with a 'Processing order' indicated by a downward arrow on the left. A 32-bit wide section is highlighted, containing four columns of bits labeled c1,j,n, c2,j,n, c3,j,n, and c4,j,n. A dashed line indicates a gap in the stream. To the right, another section shows four columns of bits labeled c1,k,n, c2,k,n, c3,k,n, and c4,k,n. A horizontal double-headed arrow labeled 'Row parity' spans across the top of the stream. A note below the stream points to the second section of bits, stating 'Assembly only modified for this codeword group'. The diagram is labeled G.975.1_FI.28.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +Figure I.28/G.975.1 – Mapping for the 25% mode. The diagram shows a horizontal bit stream with a 'Processing order' indicated by a downward arrow on the left. A 32-bit wide section is highlighted, containing four columns of bits labeled c1,j,n, c2,j,n, c3,j,n, and c4,j,n. A dashed line indicates a gap in the stream. To the right, another section shows four columns of bits labeled c1,k,n, c2,k,n, c3,k,n, and c4,k,n. A horizontal double-headed arrow labeled 'Row parity' spans across the top of the stream. A note below the stream points to the second section of bits, stating 'Assembly only modified for this codeword group'. The diagram is labeled G.975.1\_FI.28. + +**Figure I.28/G.975.1 – Mapping for the 25% mode** + +Depending on the type of information required, either the payload data FIFO or the redundancy FIFO is read out to fill the bit positions. Additionally, the 32-bit wide mapping synchronization pattern (MSync) is replaced by a string of zeros. + +##### I.7.2.3.2 Rate adaptation + +To compute the internal FEC rate $D_f$ , it is assumed that the interleaving between row and column codewords is altered in a way that both codewords fully overlap. This also requires the column codeword to be scaled by $x/y$ as seen in Figure I.29. + +![Figure I.29/G.975.1 – Simplification of interleave to support rate computation. The diagram shows two states of a codeword structure. The left state shows a rectangle of width x and height y. The top edge is labeled x, and the left edge is labeled y. Inside, there's a 'Payload' area, a 'Column parity' area at the bottom, and a 'Row parity' area on the right. A dashed line indicates a 'One bit' position. A horizontal dimension line shows a distance of x - 10*t_r. A vertical dimension line shows a distance of y - 9*t_c. A legend indicates that hatched areas represent 'FEC Parity'. An arrow points to the right state. The right state shows a similar rectangle with width x and height y. It is divided into three horizontal sections: 'Column code scaled by (x/y):' at the top, 'Row code:' in the middle, and 'Both codes "Interleaved":' at the bottom. The 'Row code:' section contains a 'Payload' area and a 'FEC Parity' area. The 'Both codes "Interleaved":' section also contains a 'Payload' area and 'FEC Parity' areas. Horizontal dimension lines show distances of 9*t_c*(x/y), 10*t_r, and x - 10*t_r - 9*t_c*(x/y). The diagram is labeled G.975.1_FI.29.](34b047489058d6400b412cd0ae2334ba_img.jpg) + +Figure I.29/G.975.1 – Simplification of interleave to support rate computation. The diagram shows two states of a codeword structure. The left state shows a rectangle of width x and height y. The top edge is labeled x, and the left edge is labeled y. Inside, there's a 'Payload' area, a 'Column parity' area at the bottom, and a 'Row parity' area on the right. A dashed line indicates a 'One bit' position. A horizontal dimension line shows a distance of x - 10\*t\_r. A vertical dimension line shows a distance of y - 9\*t\_c. A legend indicates that hatched areas represent 'FEC Parity'. An arrow points to the right state. The right state shows a similar rectangle with width x and height y. It is divided into three horizontal sections: 'Column code scaled by (x/y):' at the top, 'Row code:' in the middle, and 'Both codes "Interleaved":' at the bottom. The 'Row code:' section contains a 'Payload' area and a 'FEC Parity' area. The 'Both codes "Interleaved":' section also contains a 'Payload' area and 'FEC Parity' areas. Horizontal dimension lines show distances of 9\*t\_c\*(x/y), 10\*t\_r, and x - 10\*t\_r - 9\*t\_c\*(x/y). The diagram is labeled G.975.1\_FI.29. + +**Figure I.29/G.975.1 – Simplification of interleave to support rate computation** + +The resulting internal FEC overhead rate $D_f$ is then given by: + +$$D_f = \frac{x - 10t_r - 9\frac{x}{y}t_c}{x} = 1 - 10\frac{t_r}{x} - 9\frac{t_c}{y}$$ + +For feasible mappings, $D_f$ must be greater than the code rate $D_c$ determined by the OTUk(V) mapping as seen in Table I.11. + +**Table I.11/G.975.1 – Raw FEC rate vs OTU(V) rate** + +| | $D_f$ | $D_c$ | $D_c'$ | +|---------------------------------------------------------------|-----------------------------|---------------------------|-------------------| +| ITU-T Rec. G.709/Y.1331 compliant
OTUk framing | $4219/4500 \approx 0.9375$ | $239/255 \approx 0.9372$ | $\approx 0.9381$ | +| ITU-T Rec. G.709/Y.1331 compliant
OTUkV framing (11% mode) | $7447/8160 \approx 0.91262$ | $239/262 \approx 0.91221$ | $\approx 0.91308$ | +| ITU-T Rec. G.709/Y.1331 compliant
OTUkV framing (25% mode) | $3588/4420 \approx 0.8049$ | $239/297 \approx 0.8047$ | $\approx 0.8053$ | + +The adaptation is performed by first increasing $D_c$ to $D_c'$ by removing the 32 bits of MSync pattern when writing OTUkV data into the mapping FIFOs. + +In a second step, for each internal row codeword group $R_m$ , a dedicated column codeword group $C_a$ is selected to implement the rate adaptation. By default, this is the 10th column codeword group after start of $R_m$ . In cases where this column codeword group contains column parity, the 9th group is selected instead. + +At the beginning of the third column codeword group before $C_a$ (7th or 6th column codeword group of $R_m$ ), the fillings of the data FIFO (DFILL) and the Parity FIFO (PFILL) are checked against fixed limits (see Tables I.12 through I.14). Depending on the result of this comparison, $C_a$ is assembled from variable portions of bits from the data FIFO and the parity FIFO. Unused space is filled with zeros. Note that, yet data is pulled from the parity FIFO, it is always considered as data by the subsequent FEC decoder. + +Using the bit numbering within the column codeword group as defined in Figure I.27, $C_a$ is assembled as shown in Figure I.30. + +![Diagram of data allocation within column codeword group Ca. It shows a horizontal bar divided into three sections: Data (bits 1 to nd-1), Parity (bits nd to 128-nz), and '0' (bits 129-nz to 128). Bit positions 1, nd-1, nd, 128-nz, 129-nz, and 128 are marked along the bottom axis. The label G.975.1_FI.30 is at the bottom right.](82fbb97c1145cac89ac72dd080fad17a_img.jpg) + +Diagram of data allocation within column codeword group Ca. It shows a horizontal bar divided into three sections: Data (bits 1 to nd-1), Parity (bits nd to 128-nz), and '0' (bits 129-nz to 128). Bit positions 1, nd-1, nd, 128-nz, 129-nz, and 128 are marked along the bottom axis. The label G.975.1\_FI.30 is at the bottom right. + +**Figure I.30/G.975.1 – Data allocation within $C_a$** + +**Table I.12/G.975.1 – Rate adjustment rules for 7% OH setting (OTUk framing)** + +| Condition | | $n_d$ | $n_z$ | +|--------------|-------------|-------|-------| +| DFILL > 7168 | PFILL ≤ 896 | 104 | 24 | +| DFILL > 7168 | PFILL > 896 | 96 | 24 | +| DFILL ≤ 7168 | PFILL ≤ 896 | 88 | 40 | +| DFILL ≤ 7168 | PFILL > 896 | 80 | 40 | + +**Table I.13/G.975.1 – Rate adjustment rules for 11% OH setting (OTUkV framing)** + +| Condition | | $n_d$ | $n_z$ | +|--------------|--------------|-------|-------| +| DFILL > 6272 | PFILL ≤ 2048 | 88 | 24 | +| DFILL > 6272 | PFILL > 2048 | 80 | 24 | +| DFILL ≤ 6272 | PFILL ≤ 2048 | 72 | 40 | +| DFILL ≤ 6272 | PFILL > 2048 | 64 | 40 | + +**Table I.14/G.975.1 – Rate adjustment rules for 25% OH setting (OTUkV framing)** + +| Condition | | $n_d$ | $n_z$ | +|---------------|--------------|-------|-------| +| DFILL > 11136 | PFILL ≤ 4736 | 112 | 16 | +| DFILL > 11136 | PFILL > 4736 | 104 | 16 | +| DFILL ≤ 11136 | PFILL ≤ 4736 | 96 | 32 | +| DFILL ≤ 11136 | PFILL > 4736 | 88 | 32 | + +##### I.7.2.3.3 Mapping synchronization + +To synchronize the internal format between the sending encoder and the receiving decoder, a 32-bit wide pattern (MSync, see Figure I.25) is used. This pattern is replaced by a zero string before mapping. It conveys the following information in two alternatively inserted MSync patterns (see Figure I.31): + +**Table I.15/G.975.1 – Transmitted synchronization information** + +| Name | Size | Initialization latency $u$
in bit (see Figure I.32) | | | Function | +|-------|---------|--------------------------------------------------------|--------|--------|----------------------------------------------------------------------------------------------------------------------| +| | | 7% OH | 25% OH | 11% OH | | +| IX | 9 bits | 2400 | 7776 | 3040 | Sets the row code to process the IXth bit of codeword (initializes the row codeword allocation shown in Figure I.22) | +| PHI | 9 bits | 2400 | 7776 | 3040 | Sets the column codeword bit to PHI (initializes the column codeword allocation shown in Figure I.23) | +| PHIS | 3 bits | 2400 | 7776 | 3040 | The number of currently removed column codewords before the column codeword being initialized by PHI | +| DFILL | 14 bits | 2656 | 8032 | 3296 | Sets the filling of the data FIFO to DFILL | +| PFILL | 14 bits | 2656 | 8032 | 3296 | Sets the filling of the parity FIFO to PFILL | + +The five quantities are split over two MSync patterns transmitted alternatively in two consecutive OTU*k*(V) frames. The allocations are shown in Figure I.31. + +Transmission order → + +| | | | | | | | | | | | | +|-------------------|-----|-------------------|-------------------|-------------------|-------------------|-------------------|------------------|------------------|------------------|------------------|------------------| +| 1 | RES | IX[9:0] | PHIS[2:0] | PHI[8:0] | 1 | 0 | CRC | | | | | +| 31 | | 29 | 20 | 19 | 17 | 16 | 8 | 7 | 6 | 5 | 0 | + + + +| | | | | | | | | | | +|-------------------|-----|-------------------|-------------------|-------------------|------------------|------------------|------------------|------------------|------------------| +| 0 | RES | DFILL[12:2] | PFILL[12:2] | DFILL[13] | PFILL[13] | CRC | | | | +| 31 | | 29 | 19 | 18 | 8 | 7 | 6 | 5 | 0 | + +G.975.1\_FI.31 + +**Figure I.31/G.975.1 – Structure of the mapping synchronization pattern** + +Both patterns are protected using a 6-bit CRC added to the 24 information bits MSync[29:6]. The check matrix is given by: + +$$\text{CRC}[5:0] = \begin{bmatrix} + 1 & 1 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\ + 0 & 1 & 1 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 0 & 0 \\ + 0 & 1 & 1 & 1 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 0 & 1 & 1 & 0 & 0 \\ + 1 & 0 & 1 & 1 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 1 & 0 & 0 & 1 & 1 & 0 \\ + 0 & 0 & 0 & 1 & 1 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 1 & 1 \\ + 1 & 0 & 0 & 0 & 1 & 1 & 0 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 1 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 1 + \end{bmatrix} \text{MSync}[29:6]$$ + +The extracted information is executed *u* bits after reception of the last bit of the sync pattern containing the FIFO fill settings (PFILL, DFILL). + +Transmission order → + +MSync + +*u* bit + → + +Initialization +execution + +G.975.1\_FI.32 + +**Figure I.32/G.975.1 – Latency of initialization** + +**I.7.2.3.4 Mode configurations** + +A summary of the parameterization of the two defined modes is shown in Table I.16. + +**Table I.16/G.975.1 – Configuration summary** + +| Description | Symbol | 7% mode | 11% mode | 25% mode | +|------------------------------|----------|---------------------|---------------------|---------------------| +| Transport framing row length | a | 32640 bits | 33536 bits | 38016 bits | +| Payload length | b | 30592 bits | 30592 bits | 30592 bits | +| Code rate | – | 239/255 | 239/262 | 239/297 | +| OTU1(V)/STM-16 | – | 255/238
≈ 1.0714 | 262/238
≈ 1.1001 | 297/238
≈ 1.2479 | +| OTU2(V)/STM-64 | – | 255/237
≈ 1.0759 | 262/237
≈ 1.1054 | 297/237
≈ 1.2531 | +| OTU3(V)/STM-256 | – | 255/236
≈ 1.0805 | 262/236
≈ 1.1101 | 297/236
≈ 1.2584 | + +38 ITU-T Rec. G.975.1 (02/2004) + +**Table I.16/G.975.1 – Configuration summary** + +| Description | | Symbol | 7% mode | 11% mode | 25% mode | +|----------------------------------|-------------------------------|--------------|---------|----------|----------| +| Row code: | Codeword length | $x$ | 900 | 960 | 884 | +| | Correctable bits per codeword | $t_r$ | 4 | 5 | 11 | +| Col. code: | Codeword length | $y$ | 500 | 510 | 510 | +| | Correctable bits per codeword | $t_c$ | 1 | 2 | 4 | +| Number of column codeword groups | | $l$ | 286 | 262 | 262 | +| Column codeword shift | | $\Delta PHI$ | 286 | 296 | 296 | + +**I.7.3 Error correction capability** + +Based on the terms and definitions given in clause 7, Tables I.17 to I.19 show the results for the three different configurations. Non-shaded rows contain measured data, while shaded rows contain extrapolated data based on simulations. It is assumed the stream is decoded iteratively using the five steps, each implementing a hard decision BCH decoder as shown in Figure I.33. Different decoding strategies will deliver different performance. + +![Figure I.33/G.975.1 – Five-step iterative decoding block diagram](16fd114ddfd8734c28391a95768604ab_img.jpg) + +``` + + graph LR + A[Uncorrected input] --> B[Row decoder] + B --> C[Column decoder] + C --> D[Row decoder] + D --> E[Column decoder] + E --> F[Row decoder] + F --> G[Corrected output] + +``` + +Figure I.33/G.975.1 – Five-step iterative decoding block diagram + +**Figure I.33/G.975.1 – Five-step iterative decoding** +**Table I.17/G.975.1 – Error correcting capability of the 7% OH setting** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|------------------------|------------|----------------------|------------------|--------------| +| $2.700 \times 10^{-3}$ | $10^{-9}$ | 6.35 | 6.67 | 8.89 | +| $2.550 \times 10^{-3}$ | $10^{-10}$ | 6.80 | 7.12 | 8.95 | +| $2.400 \times 10^{-3}$ | $10^{-11}$ | 7.20 | 7.52 | 9.01 | +| $2.200 \times 10^{-3}$ | $10^{-12}$ | 7.53 | 7.85 | 9.09 | +| $2.000 \times 10^{-3}$ | $10^{-13}$ | 7.82 | 8.14 | 9.18 | +| $1.62 \times 10^{-3}$ | $10^{-14}$ | 7.98 | 8.29 | 9.38 | +| $1.30 \times 10^{-3}$ | $10^{-15}$ | 8.09 | 8.41 | 9.58 | + +**Table I.18/G.975.1 – Error correcting capability of the 11% OH setting** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|------------------------|------------|----------------------|------------------|--------------| +| $4.920 \times 10^{-3}$ | $10^{-9}$ | 6.89 | 7.32 | 8.24 | +| $4.850 \times 10^{-3}$ | $10^{-10}$ | 7.38 | 7.81 | 8.26 | +| $4.740 \times 10^{-3}$ | $10^{-11}$ | 7.81 | 8.25 | 8.28 | +| $4.630 \times 10^{-3}$ | $10^{-12}$ | 8.20 | 8.64 | 8.31 | +| $4.580 \times 10^{-3}$ | $10^{-13}$ | 8.57 | 9.01 | 8.32 | +| $4.50 \times 10^{-3}$ | $10^{-14}$ | 8.90 | 9.33 | 8.34 | +| $4.44 \times 10^{-3}$ | $10^{-15}$ | 9.19 | 9.63 | 8.36 | + + ITU-T Rec. G.975.1 (02/2004) 39 + +**Table I.19/G.975.1 – Error correcting capability of the 25% OH setting** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|------------------------|------------|----------------------|------------------|--------------| +| $1.340 \times 10^{-2}$ | $10^{-9}$ | 7.68 | 8.66 | 6.90 | +| $1.330 \times 10^{-2}$ | $10^{-10}$ | 8.17 | 9.15 | 6.91 | +| $1.323 \times 10^{-2}$ | $10^{-11}$ | 8.63 | 9.61 | 6.92 | +| $1.320 \times 10^{-2}$ | $10^{-12}$ | 9.04 | 10.02 | 6.93 | +| $1.312 \times 10^{-2}$ | $10^{-13}$ | 9.41 | 10.39 | 6.93 | +| $1.307 \times 10^{-2}$ | $10^{-14}$ | 9.75 | 10.73 | 6.94 | +| $1.302 \times 10^{-2}$ | $10^{-15}$ | 10.06 | 11.04 | 6.95 | + +![Figure I.34/G.975.1 – FEC performance input BER vs output BER. The graph shows three curves for 25%, 11%, and 7% overhead modes. The y-axis is Output BER (log scale, 1.000E-15 to 1.000E-01) and the x-axis is Input BER (log scale, 1.000E-03 to 1.000E-01). The 25% mode curve is the leftmost, followed by 11% mode, and then 7% mode. All curves show a sharp drop in Output BER as Input BER decreases.](7fef73f27d4372a53355cc9bf8ac2703_img.jpg) + +The figure is a log-log plot showing the relationship between Input BER (x-axis) and Output BER (y-axis) for three different FEC overhead modes: 25%, 11%, and 7%. The x-axis ranges from $1.000E-03$ to $1.000E-01$ , and the y-axis ranges from $1.000E-15$ to $1.000E-01$ . The 25% mode curve (triangles) shows the best performance, reaching an output BER of $10^{-15}$ at an input BER of approximately $1.3 \times 10^{-2}$ . The 11% mode curve (squares) and 7% mode curve (diamonds) show progressively worse performance, requiring higher input BERs to achieve the same output BER. + +Figure I.34/G.975.1 – FEC performance input BER vs output BER. The graph shows three curves for 25%, 11%, and 7% overhead modes. The y-axis is Output BER (log scale, 1.000E-15 to 1.000E-01) and the x-axis is Input BER (log scale, 1.000E-03 to 1.000E-01). The 25% mode curve is the leftmost, followed by 11% mode, and then 7% mode. All curves show a sharp drop in Output BER as Input BER decreases. + +**Figure I.34/G.975.1 – FEC performance input BER vs output BER** + +### I.7.4 Redundancy ratio + +In Table I.20, the FEC redundancy ratios and the net rate ratios resulting from different mapping according to ITU-T Rec. G.709/Y.1331 are shown. Note that mapping STM-64 into OTU2(V) and STM-256 into OTU3(V) imply introduction of unused fixed stuff columns, further increasing the overall rate. + +**Table I.20/G.975.1 – Redundancy ratios for different mapping** + +| | 7% OH mode | 11% OH mode | 25% OH mode | +|------------------|-----------------------------|-----------------------------|-----------------------------| +| Redundancy ratio | 255/239
$\approx 1.066$ | 262/239
$\approx 1.096$ | 297/239
$\approx 1.2426$ | +| OTU $k$ (V)/CBR | 255/238
$\approx 1.0714$ | 262/238
$\approx 1.1001$ | 297/238
$\approx 1.2479$ | +| OTU1(V)/STM-16 | 255/238
$\approx 1.0714$ | 262/238
$\approx 1.1001$ | 297/238
$\approx 1.2479$ | +| OTU2(V)/STM-64 | 255/237
$\approx 1.0759$ | 262/237
$\approx 1.1054$ | 297/237
$\approx 1.2531$ | +| OTU3(V)/STM-256 | 255/236
$\approx 1.0805$ | 262/236
$\approx 1.1101$ | 297/236
$\approx 1.2584$ | + +### I.7.5 Latency + +The latency depends on the selected implementation as well as on the number of iterations performed while decoding. However, there is a lower bound of $\sim 500$ kbit/s per column codeword processing stage. Thus the decoding strategy described in I.7.3 will lead to a latency of $\sim 1$ Mbit. In case of 10 Gbit/s payloads (STM-64, ODU2), this will result in $100 \mu\text{s}$ delay. + +### I.7.6 Properties + +The described scheme provides strong error correction capabilities over a wide range of code rates, while showing no or only very limited flaring. It does not rely on soft decision algorithms for decoding. The overall introduced latency is moderate. + +## I.8 Reed-Solomon (2720,2550) super FEC code + +### I.8.1 Overview + +Modern high-speed optical transmission systems rely heavily on forward error correction (FEC) to provide quasi error-free transmission over optical channels. ITU-T Rec. G.975 specifies the standard RS(255,239) codes with 8-bit symbols, interleaved with depth 16, as the default FEC code for optical transmission systems. This interleaved FEC code is a systematic block code of length 32640 with 30592 information-carrying bits. It can correct up to eight symbol errors in each of the 16 interleaved streams of 2040 bits. + +### I.8.2 Super FEC algorithm + +A Reed-Solomon code of length $N$ over Galois Field $\text{GF}(q)$ is a cyclic code with generator polynomial: + +$$g(x) = (x - \alpha^b)(x - \alpha^{b+1}) \cdots (x - \alpha^{b+D-2})$$ + +where $\alpha$ is a primitive element of $\text{GF}(q)$ , $D$ is the minimum distance, $k = N - D + 1$ is the dimension and $b$ is an arbitrary offset. This code, referred to as an RS( $N, K$ ) code, can correct up to $t = \lfloor (D-1)/2 \rfloor = \lfloor (N-k)/2 \rfloor$ symbol errors, where $\lfloor a \rfloor$ denotes the largest integer smaller than or equal to $a$ . For practical purposes, we consider the class of RS codes over $\text{GF}(2^m)$ , the elements of which can be represented by binary $m$ -tuples, to form an RS ( $n = mN, k = mK$ ) code over $\text{GF}(2)$ . + +Let $n_b$ denote the total block length of the frame. For $n_b > mN$ , it is common to interleave the symbols of the RS( $N, K$ ) codes to provide a high burst error correction capability, or, preferably to increase the error correction parameter $t$ and maintain the same overhead by increasing the block length $n$ , where $n \leq m(2^m - 1)$ and therefore increasing $m$ . The interleaving depth is consequently + +reduced to $u \leq \lceil n_b / m(2^m - 1) \rceil$ and $N = \lceil n_b / mu \rceil$ , where $\lceil a \rceil$ denotes the smallest integer larger than or equal to $a$ . + +Let $B_{\max}$ denote the maximum burst error length that can always be corrected. It is easy to verify that the burst error capability of an RS( $N, K$ ) code over $GF(2^m)$ with interleaving depth $u$ is given by $B_{\max} = u \cdot t$ . However, a more relevant parameter is the guaranteed burst error capability in the presence of random errors. The maximum burst error length $B_{\max}^{(v)}$ in the presence of $v$ random errors can be expressed by: + +$$B_{\max}^{(v)} = \max(0, t - v) \cdot u \text{ [m-bit symbols]}$$ + +The burst error length in bits, $b_{\max}^{(v)}$ , is consequently given by: + +$$b_{\max}^{(v)} = \max(0, mB_{\max}^{(v)} - (m - 1)) \text{ [bits]}$$ + +where the non-alignment of the beginning and end of the burst error and the $m$ -bit symbols has been taken into account. + +The error correcting capability of a bounded distance decoder is exceeded if $e > t$ symbol errors occur. The word error probability $P_w^{(n)}$ at the output of a bounded distance RS ( $n = mN, k = mk$ ) decoder after transmission over a binary symmetric channel with a bit error probability $P_b$ is therefore given by: + +$$P_w^{(n)} = \sum_{e=t+1}^N \binom{N}{e} p_s^e (1 - p_s)^{N-e}$$ + +where $p_s = 1 - (1 - p_b)^m$ is the symbol error probability. For an interleaved RS( $N, K$ ) code, the expression for the word error probability becomes: + +$$P_w^{(u \cdot n)} = 1 - (1 - P_w^{(n)})^u$$ + +If the transmitted codeword has $e > t$ symbol errors, the decoder will either fail to find a codeword (decoder failure), or it will find a codeword other than the transmitted codeword (decoder error). It has been shown in the literature that the decoder error probability is less than $1/(t!)$ . In the case of a decoder failure, the decoder will leave the received word unchanged, which effectively means that the number of symbol errors equals $e$ and the average number of bit errors equals $e \cdot mp_b / p_s$ . In the case of a decoder error up to $t$ extra random errors will be added, in which case the average number of bit errors equals $e \cdot mp_b / p_s + t \cdot m / 2$ . It follows that the bit error probability $p_b$ can now be accurately approximated by: + +$$P_b \cong \frac{1}{N} \sum_{e=t+1}^N \left( \frac{p_b}{p_s} \cdot e + \frac{1}{2(t-1)!} \right) \binom{N}{e} p_s^e (1 - p_s)^{N-e}$$ + +The following paragraph uses the derived expressions implicitly to obtain the parameters of the RS code and to determine its performance. + +The proposed FEC code is an RS(2720, 2550) code with 12-bit symbols and a total length of 32640 bits. The polynomial that generates the elements over Galois Field $GF(2^{12})$ is given by: + +$$p(x) = x^{12} + x^9 + x^8 + x^6 + x^3 + x^2 + 1$$ + +This code supports up to 30600 information-carrying bits. The first 30588 bits of the standard $239 \times 16 \times 8$ FEC frame payload will be mapped onto the first 2549 symbols. The last four bits of the payload will form the four most significant bits of the 2550th symbol and the remaining 8 bits of this symbol are unused. They can either be specified or set to zero. + +### I.8.3 Error correction ability + +The RS(2720,2550) code can correct up to 85 symbol errors, and the bit error rate at the decoder output can therefore be easily determined. The results are shown in Figures I.35 and I.36 and in Table I.21. It is clear that the low minimum distance of the RS(255,239) code, that is only able to correct up to 8 symbols in one of the interleaved 2040 bits blocks, has a severe impact on the error correction performance of the standard FEC code. The maximum burst error correction capability $b_{\max}^{(v)}$ of the RS(2720,2550) code is given by $\max(0, 12 \cdot (85 - v) - 11)$ in the presence of $v$ additional random errors. As a comparison, the interleaved RS(255,239) code is capable of correcting $\max(0, 128 \cdot (8 - v) - 7)$ . This illustrates that the burst error correction capability of the latter is much more susceptible to random errors. + +![Figure I.35/G.975.1: Output BER as a function of the input BER for the RS(2720,2550) code and the standard FEC code. The graph is a log-log plot with Input BER on the x-axis (10^-4 to 10^-2) and Output BER on the y-axis (10^-16 to 10^0). Two curves are shown: a dashed line for RS(255,239) and a solid line for RS(2720,2550). The RS(255,239) curve starts at an output BER of 10^-16 at an input BER of approximately 10^-4.5 and rises to an output BER of 10^-2 at an input BER of 10^-2. The RS(2720,2550) curve starts at an output BER of 10^-16 at an input BER of approximately 10^-3.2 and rises to an output BER of 10^-2 at an input BER of 10^-2. The RS(2720,2550) curve shows a steeper initial rise but is eventually overtaken by the RS(255,239) curve at higher input BER values.](9f92854fe6ecaf47760515c891a4fccc_img.jpg) + +Figure I.35/G.975.1: Output BER as a function of the input BER for the RS(2720,2550) code and the standard FEC code. The graph is a log-log plot with Input BER on the x-axis (10^-4 to 10^-2) and Output BER on the y-axis (10^-16 to 10^0). Two curves are shown: a dashed line for RS(255,239) and a solid line for RS(2720,2550). The RS(255,239) curve starts at an output BER of 10^-16 at an input BER of approximately 10^-4.5 and rises to an output BER of 10^-2 at an input BER of 10^-2. The RS(2720,2550) curve starts at an output BER of 10^-16 at an input BER of approximately 10^-3.2 and rises to an output BER of 10^-2 at an input BER of 10^-2. The RS(2720,2550) curve shows a steeper initial rise but is eventually overtaken by the RS(255,239) curve at higher input BER values. + +Figure I.35/G.975.1 – Output BER as a function of the input BER for the RS(2720,2550) code and the standard FEC code + +![Figure I.36/G.975.1: Output BER as a function of the input Eb/N0 for the RS(2720,2550) code and the standard FEC code. The graph shows three curves: 'uncoded' (dash-dot line), 'RS(255,239)' (dashed line), and 'RS(2720,2550)' (solid line). The x-axis is 'Electrical SNR [dB]' from 5 to 16. The y-axis is 'Output BER' on a logarithmic scale from 10^0 to 10^-16. The RS(2720,2550) curve shows a sharp drop in BER around 7 dB SNR, reaching 10^-16 by 8 dB. The RS(255,239) curve drops around 8 dB SNR, reaching 10^-16 by 9 dB. The uncoded curve drops more gradually, reaching 10^-16 by 15 dB.](6ef03c6e28f2f1fd4f98529146ffeccc_img.jpg) + +Figure I.36/G.975.1: Output BER as a function of the input Eb/N0 for the RS(2720,2550) code and the standard FEC code. The graph shows three curves: 'uncoded' (dash-dot line), 'RS(255,239)' (dashed line), and 'RS(2720,2550)' (solid line). The x-axis is 'Electrical SNR [dB]' from 5 to 16. The y-axis is 'Output BER' on a logarithmic scale from 10^0 to 10^-16. The RS(2720,2550) curve shows a sharp drop in BER around 7 dB SNR, reaching 10^-16 by 8 dB. The RS(255,239) curve drops around 8 dB SNR, reaching 10^-16 by 9 dB. The uncoded curve drops more gradually, reaching 10^-16 by 15 dB. + +**Figure I.36/G.975.1 – Output BER as a function of the input $E_b/N_0$ for the RS(2720,2550) code and the standard FEC code** + +**Table I.21/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q-limit (dB) | +|-----------------------|------------|----------------------|------------------|--------------| +| $1.48 \times 10^{-3}$ | $10^{-9}$ | 5.82 | 6.10 | 9.46 | +| $1.40 \times 10^{-3}$ | $10^{-10}$ | 6.28 | 6.56 | 9.51 | +| $1.33 \times 10^{-3}$ | $10^{-11}$ | 6.70 | 6.98 | 9.56 | +| $1.26 \times 10^{-3}$ | $10^{-12}$ | 7.06 | 7.35 | 9.60 | +| $1.20 \times 10^{-3}$ | $10^{-13}$ | 7.40 | 7.69 | 9.65 | +| $1.15 \times 10^{-3}$ | $10^{-14}$ | 7.71 | 8.00 | 9.68 | +| $1.10 \times 10^{-3}$ | $10^{-15}$ | 8.00 | 8.28 | 9.72 | + +### I.8.4 Redundancy ratio + +The redundancy ratio of the Interleaved Reed-Solomon (2720,2550) Code is with 7% the same as the legacy RS FEC as defined in ITU-T Rec. G.975. + +### I.8.5 Latency + +This RS(2720,2550) code with 12-bit symbols and a block length of 32640 bits and a 30592 bits is shown to have a low latency that is of the same order as for the interleaved RS(255,239) code. + +### I.8.6 Property + +This 85-error correcting RS(2720,2550) code with 12-bit symbols has a block length of 32640 bits and a 30592 bits payload, identical to the standard RS(255,239) code. It has been shown to achieve a significant coding gain and to have superior burst correction capabilities. The encoder and decoder can be implemented efficiently in the current chip technologies for 2.5G, 10G and + +40G applications, and is shown to have a low latency that is of the same order as for the interleaved RS(255,239) code. + +## I.9 Two interleaved extended BCH(1020,988) super FEC code + +### I.9.1 Overview + +The proposed FEC consists of two interleaved extended BCH(1020,988) codes with the same block-length. The Overall FEC block-length and payload length is (522240,489472) that is in line with overhead ratio defined in ITU-T Recs G.975 or G.709/Y.1331. The net coding gain of this code is better than 8.5 dB at BER $10^{-13}$ , with a 10 times iterative decoding. + +### I.9.2 Super FEC algorithm + +The enhanced FEC scheme uses two interleaved extended BCH(1020,988) codes with the same block-length, as described below. + +#### I.9.2.1 BCH(1020,988) + +The field polynomial is: + +$$p(x) = x^{10} + x^3 + 1$$ + +The code generator polynomials for the horizontal and the sloping codes are: + +$$g_H(x) = m_1(x) m_3(x) m_5(x) (x^2 + 1)$$ + +$$g_s(x) = x^{30} m_1(x^{-1}) m_3(x^{-1}) m_5(x^{-1}) (x^2 + x + 1)$$ + +being: + +$$m_1(x) = x^{10} + x^3 + 1$$ + +$$m_3(x) = x^{10} + x^3 + x^2 + x + 1$$ + +$$m_5(x) = x^{10} + x^8 + x^3 + x^2 + 1$$ + +#### I.9.2.2 Frame structure + +The payload of 16 G.709/Y.1331 ODUs is collected in order to build a BCH super frame. So there are 3824 bit vectors containing 128 bits each, indexed according to the order of transmission, forming the following $512 \times 956$ bit-matrix. + +| | | | | | | | | | | | | | | +|---|---|----|--|--|--|----|--|------|--|--|--|------|------| +| 0 | 4 | 8 | | | | 24 | | 3800 | | | | 3816 | 3820 | +| 1 | 5 | 9 | | | | 25 | | 3801 | | | | 3817 | 3821 | +| 2 | 6 | 10 | | | | 26 | | 3802 | | | | 3818 | 3822 | +| 3 | 7 | 11 | | | | 27 | | 3803 | | | | 3819 | 3823 | + +The overall frame ( $512 \times 1020$ matrix) is obtained by appending $512 \times 64$ parity bits, i.e., by adding 64 columns at the right side. + +The order of transmission of the data bits is preserved. + +#### I.9.2.3 Interleaving function + +The overall frame, composed of $512 \times 1020$ bits, is divided into $16 \times 32$ sub-blocks. The rows are padded with four bits set to zero, adding four columns at the left side of the structure; obviously, those bits are not transmitted. + +Each sub-block is a square containing $32 \times 32$ bits. + +The blocks on the columns 2,3 ... 31 contain the payload bits, while the blocks on the columns 0-1 contain the parity bits. + +| | | | | | +|-------|-------|-------|-------|-------| +| 0,31 | 0,30 | 0,29 | 0,28 | 0,27 | +| 1,31 | 1,30 | 1,29 | 1,28 | 1,27 | +| 2,31 | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| 14,31 | 14,30 | 14,29 | 14,28 | 14,27 | +| 15,31 | 15,30 | 15,29 | 15,28 | 15,27 | + +| | | | | | +|------|------|------|------|------| +| 0,4 | 0,3 | 0,2 | 0,1 | 0,0 | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | | +| | | | | 14,0 | +| 15,4 | 15,3 | 15,2 | 15,1 | 15,0 | + +The interleaving function shifts the blocks inside each column, giving the following matrix: + +| | | | | | +|-------|-------|-------|-------|-------| +| 15,31 | 15,30 | 14,29 | 14,28 | 13,27 | +| 0,31 | 0,30 | 15,29 | 15,28 | 14,27 | +| 1,31 | 1,30 | 0,29 | 0,28 | 15,27 | +| 2,31 | 2,30 | 1,29 | 1,28 | 0,27 | +| | | | | 1,27 | +| | | | | 2,27 | +| | | | | 3,27 | +| | | | | 4,27 | +| | | | | 5,27 | +| 8,31 | 8,30 | 7,29 | 7,28 | 6,27 | +| | | | | 7,27 | +| | | | | 8,27 | +| | | | | 9,27 | +| | | | | 10,27 | +| 13,31 | 13,30 | 12,29 | 12,28 | 11,27 | +| 14,31 | 14,30 | 13,29 | 13,28 | 12,27 | + +| | | | | | +|------|------|------|------|------| +| 2,4 | 1,3 | 1,2 | 0,1 | 0,0 | +| 3,4 | 2,3 | 2,2 | 1,1 | 1,0 | +| 4,4 | 3,3 | 3,2 | 2,1 | 2,0 | +| 5,4 | | | | | +| 6,4 | | | | | +| 7,4 | | | | | +| 8,4 | | | | | +| 9,4 | | | | | +| 10,4 | | | | | +| 11,4 | 10,3 | 10,2 | 9,1 | 9,0 | +| 12,4 | | | | | +| 13,4 | | | | | +| 14,4 | 13,3 | 13,2 | 12,1 | 12,0 | +| 15,4 | 14,3 | 14,2 | 13,1 | 13,0 | +| 0,4 | 15,3 | 15,2 | 14,1 | 14,0 | +| 1,4 | 0,3 | 0,2 | 15,1 | 15,0 | + +Also, the interleaving function shifts the bits inside the columns of each block. So the following block: + +| | | | | | | | +|-------|-------|-------|--|------|------|------| +| 0,31 | 0,30 | 0,29 | | 0,2 | 0,1 | 0,0 | +| 1,31 | 1,30 | 1,29 | | | | 1,0 | +| 2,31 | 2,30 | 2,29 | | | | 2,0 | +| | | | | | | | +| | | | | | | 29,0 | +| | | | | | | 30,0 | +| 31,31 | 31,30 | 31,29 | | 31,2 | 31,1 | 31,0 | + +Becomes: + +| | | | | | | | +|-------|-------|-------|--|-----|------|------| +| 0,31 | 31,30 | 30,29 | | 3,2 | 2,1 | 1,0 | +| 1,31 | 0,30 | 31,29 | | 4,2 | 3,1 | 2,0 | +| 2,31 | 1,30 | 0,29 | | 5,2 | 4,1 | 3,0 | +| | | | | | | | +| 29,31 | 28,30 | 27,29 | | 0,2 | 31,1 | 30,0 | +| 30,31 | 29,30 | 28,29 | | 1,2 | 0,1 | 31,0 | +| 31,31 | 30,30 | 29,29 | | 2,2 | 1,1 | 0,0 | + +The interleaving function can also be expressed with a simple formula; the bit lying in the position [I,J], (with $0 \leq I \leq 511$ , $0 \leq J \leq 1023$ ) goes in the position: + +$[((I-J-1 \text{ MOD } 32) + 32 (I/32 - J/64) \text{ MOD } 512), J]$ , with "/" representing integer division. + +The parity bits are computed with the constraint that, every row (there are 512 rows) of the overall frame is a BCH(1020,988) codeword and, every row (there are 512 rows) of the interleaved overall frame is a BCH(1020,988) codeword. It follows that every transmitted bit is protected by two BCH codes. + +A key property of this interleaving function is that the column index remains unchanged. This allows the horizontal and sloping BCH encoders to process in parallel the same incoming data bits, without intermediate storage. + +Columns from 0 to 63 contain the parity bits, and are transmitted interleaved with data in order to preserve the standard data structure, that is each ODU is followed by 2048 bits belonging to the same overall frame. + +The order of transmission of the parity bits is as follows: + +For T = 0 to 32767 +Row = T MOD 64 + 64 (T/4096) +Column = 63 – (T MOD 4096)/64 +Send\_bit(Row, Column) +End + +#### 1.9.2.4 Encoder + +The final result of this process is to obtain that each row is a BCH codeword both before and after the interleaving function. We obtain that using superposition of effects. + +Consider the parity blocks (0,1) and (0,0), the same process is repeated on the remaining 15 block rows. + +First consider the horizontal code; block (0,1) is set to zero (1024 zeros) and for each of the 32 rows the remainders by $g_H(x)$ are carried out. This 1024 bits result is collected in the vector $p_H$ . + +The sloping code works on the rows of the interleaved frame; note that the parity blocks have the same position. Block (0,1) is set to zero, and for each of the 32 rows the remainders by $g_S(x)$ are carried out. This 1024 bits result is collected in the vector $p_S$ . + +Now, the bits inside the block (0,1), denoted as vector $q$ , are constrained to give the same total parity for both codes. + +Named $M_H$ and $M_T$ as the linear operators representing the remainder operation from block (0,1) to block (0,0), and $T$ as the interleaving matrix, we have: + +$$T(M_H q + p_H) = M_S T q + p_S \Rightarrow q = (T M_H - M_S T)^{-1} (p_S - T p_H)$$ + +Finally, the content of the blocks (0,1) and (0,0) are set to be, respectively, $q$ and $M_H q + p_H$ . + +#### 1.9.2.5 Iterative decoding + +Clearly, error correction capability increases with the number of iterations. This number can be vendor specific. However, due to the simplicity of the interleaving function and the low degree of the BCH polynomials, a number of 12 to 20 iterations can be easily reached. + +Decoding by erasure filling is also possible and suggested. For example, the most probable error pattern that is not correctable by the BCH decoders is composed by 8-bit error belonging to a couple of horizontal codewords and a couple of sloping codewords; this pattern is easily recognized and corrected. Similar and minor order error patterns can be filled with a low complexity erasure algorithm. + +### 1.9.3 Error correction ability + +Error correction capabilities of this enhanced FEC scheme depend on the number of iteration used in the decoding process. When a 10 times iterative decoding process is implemented, the performances of the code are listed in Table I.22 (results are derived from simulations). + +**Table I.22/G.975.1 – Summary for correction ability** + +| Input BER | Output BER | Net coding gain (dB) | Coding gain (dB) | Q factor (dB) | +|-----------|------------|----------------------|------------------|---------------| +| 5.00E-03 | 3.07E-03 | 0.25 | 0.54 | 8.22 | +| 4.70E-03 | 8.87E-04 | 1.33 | 1.61 | 8.29 | +| 4.50E-03 | 4.42E-05 | 3.25 | 3.53 | 8.34 | +| 4.30E-03 | 9.30E-08 | 5.67 | 5.95 | 8.39 | +| 4.00E-03 | 7.00E-14 | 8.63 | 8.91 | 8.47 | +| 3.50E-03 | 2.10E-14 | 8.67 | 8.95 | 8.62 | + +In case an erasure algorithm is used, as previously suggested, performance can be improved, obtaining, e.g., an output BER less than 10E-16 for an input BER equal to 4.00E-03. + +Figures I.37 and I.38 represent the performances of the described enhanced FEC, in terms of BER versus Q factor and in terms of Output BER versus Input BER. + +![Figure I.37/G.975.1 – Coding gain. A log-linear plot showing Bit error rate (BER) on the y-axis (10^0 to 10^-16) versus Q factor per information bit [dB] on the x-axis (7 to 18). Four curves are shown: Uncoded (green dash-dot), RS(255,239) (ITU-T) (red dashed), Super FEC without erasures (black solid with circles), and Super FEC with erasures (blue dashed). The Super FEC without erasures curve drops sharply at approximately 8.57 dB, while the RS(255,239) curve drops at approximately 17 dB. The Super FEC with erasures curve drops at approximately 8.57 dB. The label G.975.1_FI.37 is in the bottom right corner.](64aba6d3bacc69b7b90f08e02f2d5efe_img.jpg) + +Figure I.37/G.975.1 – Coding gain. A log-linear plot showing Bit error rate (BER) on the y-axis (10^0 to 10^-16) versus Q factor per information bit [dB] on the x-axis (7 to 18). Four curves are shown: Uncoded (green dash-dot), RS(255,239) (ITU-T) (red dashed), Super FEC without erasures (black solid with circles), and Super FEC with erasures (blue dashed). The Super FEC without erasures curve drops sharply at approximately 8.57 dB, while the RS(255,239) curve drops at approximately 17 dB. The Super FEC with erasures curve drops at approximately 8.57 dB. The label G.975.1\_FI.37 is in the bottom right corner. + +Figure I.37/G.975.1 – Coding gain + +![Figure I.38/G.975.1 – FEC performance. A log-log plot showing Output bit error rate on the y-axis (10^-2 to 10^-16) versus Input bit error rate on the x-axis (10^-4 to 10^-2). Three curves are shown: RS(255,239) (ITU-T) (red solid), Super FEC without erasures (black solid with circles), and Super FEC with erasures (blue dashed). The RS(255,239) curve is a straight line with a positive slope. The Super FEC without erasures curve shows a sharp drop in output BER at an input BER of approximately 10^-3. The Super FEC with erasures curve shows a sharp drop in output BER at an input BER of approximately 10^-3. The label G.975.1_FI.38 is in the bottom right corner.](3c47f29e8e1963959009844c7f3ee025_img.jpg) + +Figure I.38/G.975.1 – FEC performance. A log-log plot showing Output bit error rate on the y-axis (10^-2 to 10^-16) versus Input bit error rate on the x-axis (10^-4 to 10^-2). Three curves are shown: RS(255,239) (ITU-T) (red solid), Super FEC without erasures (black solid with circles), and Super FEC with erasures (blue dashed). The RS(255,239) curve is a straight line with a positive slope. The Super FEC without erasures curve shows a sharp drop in output BER at an input BER of approximately 10^-3. The Super FEC with erasures curve shows a sharp drop in output BER at an input BER of approximately 10^-3. The label G.975.1\_FI.38 is in the bottom right corner. + +Figure I.38/G.975.1 – FEC performance + +### I.9.4 Redundancy ratio + +The redundancy ratio of the described coding scheme is equal to 6.69%, equal to the standard RS(255,239) described in ITU-T Rec. G.709/Y.1331. + +### **I.9.5 Latency** + +The latency for a 10 Gbit/s payload is around 50 $\mu\text{s}$ for the encoder, while for the decoder it is around 100 $\mu\text{s}$ . + +### **I.9.6 Property** + +The enhanced FEC scheme generates a coded signal bit rate which is exactly the bit rate defined by ITU-T Rec. G.709/Y.1331. Moreover, despite the great block-length, the decoding machine can be implemented with a very low number of circuit elements. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure, Internet protocol aspects and Next Generation Networks | +| Series Z | Languages 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b/marked/G/T-REC-G.9802.1-202108-I_PDF-E/raw.md @@ -0,0 +1,666 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9802.1** + +(08/2021) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – Optical line systems for local and +access networks + +--- + +**Wavelength division multiplexed passive optical +networks (WDM PON): General requirements** + +Recommendation ITU-T G.9802.1 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9802.1 + +## Wavelength division multiplexed passive optical networks (WDM PON): General requirements + +## Summary + +Recommendation ITU-T G.9802.1 describes the general requirements for wavelength routed ODN based WDM PON. The general architecture and system level requirements, such as line rates, capacity in terms of channel count, optical line terminal (OLT) and optical network unit (ONU) modularity, and security are given. The symmetric nominal line rate combinations of 25 Gbit/s and 10 Gbit/s per wavelength channel are supported. The requirements for a range of relevant applications are described in terms of the needed interfaces, physical layer, operation, synchronization, resilience and protection options. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.9802.1 | 2021-08-06 | 15 | 11.1002/1000/14633 | + +## Keywords + +BiDi, single fibre transmission, WDM access, WDM PON. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2021 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|----------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 3 | +| 4 Abbreviations and acronyms ..... | 3 | +| 5 Conventions ..... | 4 | +| 6 Architecture of the WR-ODN based WDM PON ..... | 4 | +| 6.1 System architecture overview..... | 4 | +| 6.2 Common requirements ..... | 4 | +| 6.3 WR-ODN system reference layering..... | 5 | +| 6.4 Compatibility and migration scheme..... | 5 | +| 7 Service requirements ..... | 6 | +| 7.1 Service specific requirements..... | 6 | +| 7.2 User network interfaces (UNI) ..... | 6 | +| 7.3 Service node interfaces (SNI)..... | 7 | +| 7.4 Access node interfaces (ANI)..... | 8 | +| 7.5 Synchronization and clock transfer ..... | 8 | +| 8 Physical layer requirements ..... | 8 | +| 8.1 Capacity ..... | 8 | +| 8.2 Support for multiple channel pairs ..... | 9 | +| 8.3 Wavelength router capability ..... | 9 | +| 8.4 Fibre type and fibre reach..... | 9 | +| 9 System level requirements ..... | 9 | +| 9.1 Pay as you grow expectations..... | 9 | +| 9.2 OLT side modularity ..... | 10 | +| 9.3 ONU side modularity ..... | 10 | +| 9.4 Interoperability ..... | 10 | +| 9.5 Security ..... | 10 | +| 10 Operational requirements..... | 10 | +| 10.1 Provisioning method..... | 10 | +| 10.2 Test and diagnostics function ..... | 11 | +| 10.3 System management and monitoring ..... | 11 | +| 10.4 System troubleshooting ..... | 12 | +| 10.5 Environmental and physical requirements ..... | 12 | +| 10.6 Energy saving objectives ..... | 12 | +| 10.7 Eye safety ..... | 12 | + +| | Page | +|----------------------------------------------------------------|-------------| +| 11 Resilience and protection on ODN ..... | 13 | +| 11.1 Rogue behaviour prevention, detection and mitigation..... | 13 | +| 11.2 CT failure protection ..... | 13 | +| 11.3 ODN failure protection..... | 14 | +| Bibliography..... | 16 | + +## Recommendation ITU-T G.9802.1 + +## Wavelength division multiplexed passive optical networks (WDM PON): General requirements + +# 1 Scope + +This Recommendation, as part of the multi-wavelength passive optical network (MW-PON) [ITU-T G.9802] series Recommendation, describes the general requirements of wavelength division multiplexing (WDM) PON using wavelength routed optical distribution network (WR-ODN), i.e., based on a wavelength multiplexer in the optical distribution network (ODN). + +It describes requirements of WR-ODN based WDM PON, including general system architecture, service requirements, physical layer requirements (e.g., reach, channel count options), system level requirements (e.g., line rates, coexistence), and operational requirements (e.g., guidelines for provisioning, monitoring, energy efficiency). + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*. +- [ITU-T G.657] Recommendation ITU-T G.657 (2016), *Characteristics of a bending-loss insensitive single-mode optical fibre and cable*. +- [ITU-T G.986] Recommendation ITU-T G.986 (2010), *1 Gbit/s point-to-point Ethernet-based optical access system*. +- [ITU-T G.987] Recommendation ITU-T G.987 (2012), *10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations and acronyms*. +- [ITU-T G.988] Recommendation ITU-T G.988 (2017), *ONU management and control interface (OMCI) specification*. +- [ITU-T G.989] Recommendation ITU-T G.989 (2015), *40-Gigabit-capable passive optical networks (NG-PON2): Definitions, abbreviations and acronyms*. +- [ITU-T G.989.1] Recommendation ITU-T G.989.1 (2013), *40-Gigabit-capable passive optical networks (NG-PON2): General requirements*. +- [ITU-T G.989.2] Recommendation ITU-T G.989.2 (2019), *40-Gigabit-capable passive optical networks 2 (NG PON2): Physical media dependent (PMD) layer specification*. +- [ITU-T G.989.3] Recommendation ITU-T G.989.3 (2021), *40-Gigabit-capable passive optical networks (NG-PON2): Transmission convergence layer specification*. + +- [ITU-T G.8261] Recommendation ITU-T G.8261 (2019), *Timing and synchronization aspects in packet networks*. +- [ITU-T G.8262] Recommendation ITU-T G.8262 (2018), *Timing characteristics of a synchronous equipment slave clock*. +- [ITU-T G.9802] Recommendation ITU-T G.9802 (2015), *Multiple-wavelength passive optical networks (MW-PONs)*. +- [ITU-T G.9806] Recommendation ITU-T G.9806 (2020), *Higher speed bidirectional, single fibre, point-to-point optical access system (HS-PtP)*. +- [ITU-T G.9807.1 Amd. 1] Recommendation ITU-T G.9807.1 Amd. 1 (2017), *10-Gigabit-capable symmetric passive optical network (XGS-PON)*. +- [BBF TR-156] Broadband Forum Technical Report BBF TR-156 (2017), *Using GPON Access in the context of TR-101*. +- [IEC 60825-2] International Standard IEC 60825-2 (2004), *Safety of laser products – Part 2: Safety of optical fibre communication systems (OFCS)*. +- [IEEE 802.3] IEEE Standards Association IEEE 802.3 (2008), *IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications*. +- [IEEE 1588] IEEE Standards Association IEEE 1588 (2019), *IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems*. +- [IEEE 1588v2] IEEE Standards Association IEEE 1588v2 (2021), *Precision Timing Protocol (PTP)*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined in [ITU-T G.987]: + +**3.1.1 optical distribution network (ODN):** A point-to-multipoint optical fibre infrastructure. A *simple* ODN is entirely passive and is represented by a single-rooted point-to-multipoint tree of optical fibres with splitters, combiners, filters, and possibly other passive optical components. A *composite* ODN consists of two or more passive *segments* interconnected by active devices, each of the segments being either an optical trunk line segment or an optical distribution segment. A passive optical distribution segment is a simple ODN itself. Two ODNs with distinct roots can share a common subtree. + +**3.1.2 optical line termination (OLT):** A network element in an ODN-based optical access network that terminates the root of at least one ODN and provides an optical access network (OAN) service node interface (SNI). + +**3.1.3 optical network unit (ONU):** A network element in an ODN-based optical access network that terminates a leaf of the ODN and provides an OAN user network interface (UNI). + +**3.1.4 passive optical network (PON) system:** A combination of network elements in an ODN-based optical access network that includes an OLT and multiple ONUs and implements a particular coordinated suite of physical medium dependent layer, transmission convergence layer, and management protocols. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following term: + +**3.2.1 OLT CT:** Each of the physical ports in the optical line terminal (OLT) that connects to/from a fibre of the optical distribution network (ODN) is named as channel termination (CT). In the context of wavelength router-based transmission it is interpreted as terminating a channel pair (CP). + +**3.2.2 channel pair:** A set of one downstream wavelength channel and one upstream wavelength channel that provides connectivity between an OLT and one ONU. + +**3.2.3 channel group:** A set of channel pairs (CPs) carried over a common fibre. + +**3.2.4 inter channel termination protocol (ICTP):** A protocol that is executed between the OLT CTs to enable functions such as protection management. + +**3.2.5 multiple channel termination module (MCT):** A specific implementation at the OLT network element that terminates multiple WR-ODN based WDM PON system (WRP) channels within a single physical module in a WRP system. + +**3.2.6 wavelength routed ODN:** An optical distribution network where the branching node (splitter) is wavelength selective and the port to which an ONU is connected determines the channel pair (CP) to be used for communications. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|-----------------------------------------------------------| +| AN | Access Node | +| CBU | Cellular Backhaul Unit type ONU | +| CG | Channel Group | +| CP | Channel Pair | +| CPRI | Common Public Radio Interface | +| CT | Channel Termination | +| ICTP | Inter Channel Termination Protocol | +| MCT | Multi Channel Termination Module | +| OAM | Operations, Administration and Maintenance | +| OAN | Optical Access Network | +| OBSAI | Open Base Station Standard Initiative | +| OC | Operation Control | +| ODN | Optical Distribution Network | +| OLT | Optical Line Terminal | +| ONU | Optical Network Unit | +| OPS | Optical (achromatic) Power Splitter | +| PAYG | Pay As You Grow | +| PLOAM | Physical Layer Operations, Administration and Maintenance | +| PON | Passive Optical Network | +| R/S | Receive/Send Reference point at ONU side | + +| | | +|--------|------------------------------------------| +| SNI | Service Node Interface | +| S/R | Send/Receive Reference point at OLT side | +| UNI | User Network Interface | +| WDM | Wavelength Division Multiplexing | +| WR | Wavelength Router | +| WRP | WR-ODN based WDM PON system | +| WR-ODN | Wavelength Routed ODN | + +# 5 Conventions + +This Recommendation uses conventions defined in [ITU-T G.9802]. + +# 6 Architecture of the WR-ODN based WDM PON + +## 6.1 System architecture overview + +A WR-ODN based WDM PON system (WRP) consists of the wavelength multiplexing of several channel terminations (CTs), each providing bi-directional connectivity through a pair of wavelengths constituting a channel pair (CP). The system architecture described in this Recommendation is adapted from Figures 6-1 and 6-11 in [ITU-T G.9802]. + +The passive wavelength router (WR) sits in the ODN routes in each of the CP constitutive of the channel group (CG), towards a different physical drop port. In Figure 6-1, the ODN wavelength routing function is located in a single device, multiple stage structures are also possible but out of the scope of this Recommendation. + +In Figure 6-1, all CTs are located in the same OLT chassis, and each ONU is associated with a single CP, where the access node (AN) side WR may reside in the OLT chassis. Options in which CPs are originated from different OLT chassis and ONU retrieving several CPs are also possible. Both these options are out of scope of this Recommendation. + +NOTE – Since no backward compatibility with legacy ONUs is considered, the term ONU is equivalent to WRP ONU in the present Recommendation. + +![Figure 6-1: Functional architecture and reference points for WRP. The diagram shows an OLT chassis on the left connected to an SNI. Inside the OLT chassis are multiple OLT CTs (CT-1, CT-2, CT-3, ..., CT-n), each connected to a Wavelength router (AN). The Wavelength router (AN) is connected to an ODN (Optical Distribution Network) via an S/R-CG reference point. The ODN is connected to another Wavelength router (ODN) via an R/S reference point. This second Wavelength router (ODN) is connected to multiple ONUs (ONU-1, ONU-2, ..., ONU-n), each connected to a UNI reference point.](1eadbbe42cfcac5c0023577110aec5e3_img.jpg) + +The diagram illustrates the functional architecture of a Wavelength Routed Optical Distribution Network (WR-ODN) based Wavelength Division Multiplexing Passive Optical Network (WDM PON) system. On the left, an OLT chassis is connected to a Service Node Interface (SNI). Inside the OLT chassis, there are multiple Optical Line Terminal Channel Terminations (OLT CTs), labeled OLT CT-1, OLT CT-2, OLT CT-3, and OLT CT-n. Each OLT CT is connected to a Wavelength router (AN) via a channel pair (CP) labeled S/R-CP1, S/R-CP2, S/R-CP3, and S/R-CPn. The Wavelength router (AN) is connected to an Optical Distribution Network (ODN) via an S/R-CG reference point. The ODN is connected to another Wavelength router (ODN) via an R/S reference point. This second Wavelength router (ODN) is connected to multiple Optical Network Units (ONUs), labeled ONU-1, ONU-2, and ONU-n. Each ONU is connected to a User Network Interface (UNI). The diagram is labeled G.9802.1(21) in the bottom right corner. + +Figure 6-1: Functional architecture and reference points for WRP. The diagram shows an OLT chassis on the left connected to an SNI. Inside the OLT chassis are multiple OLT CTs (CT-1, CT-2, CT-3, ..., CT-n), each connected to a Wavelength router (AN). The Wavelength router (AN) is connected to an ODN (Optical Distribution Network) via an S/R-CG reference point. The ODN is connected to another Wavelength router (ODN) via an R/S reference point. This second Wavelength router (ODN) is connected to multiple ONUs (ONU-1, ONU-2, ..., ONU-n), each connected to a UNI reference point. + +**Figure 6-1 – Functional architecture and reference points for WRP** + +## 6.2 Common requirements + +The WRP systems should support: + +- The symmetric nominal line rate combination options per CP: + - 25 Gbit/s + - 10 Gbit/s + - other nominal line rates are FFS +- Simultaneous support of 25 Gbit/s CT and 10 Gbit/s CT on different CPs are required. The nominal line rate per CP can be changed by replacing the CT. +- 12/20/40 wavelength CPs for WR-ODN. +- A WRP ONU shall be wavelength agnostic and usable on any of the ONU side ports of the WR in the ODN. + +## 6.3 WR-ODN system reference layering + +The layered structure of a WRP is shown in Table 6-1. The protocol reference model is divided into the transmission convergence (TC) and physical medium dependent (PMD) layers, which are the two layers considered in this Recommendation. + +The WRP TC layer is divided into PON transmission and adaptation sublayers, which correspond to the transmission convergence sublayer of the tributary units conveying various data types. The PON transmission sublayer terminates the required transmission function on the ODN. The PON-specific functions are terminated by the PON transmission sublayer, and it is not seen from the adaptation sublayer. + +**Table 6-1 – Layered structure of WRP** + +| Path layer | | | | +|---------------------------------|---------------------------------------|--------------|---------------------------------------------------------------------------------------------| +| Transmission media layer – Note | Transmission convergence (TC) layer | Adaptation | Encapsulation | +| | | Transmission | Service transporting
Privacy and security
Synchronization
Management capabilities | +| | Physical medium dependent (PMD) layer | | Electrical/optical adaptation
Wavelength division multiplexing (WDM)
Fibre connection | + +NOTE – The transmission medium layer must provide the related operations, administration and maintenance (OAM) functions. + +## 6.4 Compatibility and migration scheme + +Two main scenarios for WRP have been identified: + +- Greenfield in which the ODN will be newly built; +- Brownfield in which WRP will be used to upgrade an existing single fibre link, as shown in Figure 6-2. + +While in the greenfield scenario, the optical budget is not constrained, convergence with existing well established budget classes is preferable to maximize the benefit from existing modules and avoid an optoelectronic modules market split. + +Thus, the optical budget classes of [ITU-T G.989] and [ITU-T G.9806] will be considered for re-use. + +When WRP systems are intended for brownfield deployment, the ability to cover the legacy optical budget classes of point-to-point ODNs defined in [ITU-T G.986] and [ITU-T G.9806] is required. + +Thus, solutions for legacy optical budget classes with the addition of the WR device's insertion loss are necessary, as represented in Figure 6-2. Class « x » is to be understood as any of the relevant legacy optical budget classes with also due consideration of the legacy link length. + +![Figure 6-2: Upgrade example of a legacy link (at the top) to a multi-channel one (bottom).](042733dc5e8e7f5f30b60adba3266cde_img.jpg) + +The diagram illustrates two optical network configurations. The top configuration shows a legacy point-to-point link: an OLT chassis with a BiDi CT is connected via an S/R interface to an ONU via an R/S interface. The optical path is labeled 'ODN class <>'. The bottom configuration shows a multi-channel upgrade: an OLT chassis contains multiple OLT CTs (CT-1, CT-2, CT-3, ..., CT-n) connected to a Wavelength router (AN) via S/R-CP interfaces (CP1, CP2, CP3, ..., CPn). The Wavelength router (AN) is connected to a Wavelength router (ODN) via an S/R-CG interface. The Wavelength router (ODN) is connected to multiple ONUs (ONU-1, ONU-2, ..., ONU-n) via R/S interfaces. The optical path from the Wavelength router (AN) to the Wavelength router (ODN) is labeled 'ODN class <> + WR insertion loss'. A separate path from the Wavelength router (AN) to the Wavelength router (ODN) is labeled 'Legacy ODN path loss and distance'. The interfaces are labeled SNI, S/R, R/S, and UNI. + +Figure 6-2: Upgrade example of a legacy link (at the top) to a multi-channel one (bottom). + +**Figure 6-2 – Upgrade example of a legacy link (at the top) to a multi-channel one (bottom)** + +In addition to line rate and distance options, full simultaneous mixing of CT/CPs with different optical budget classes is required. + +Pay as you grow (PAYG) provisioning of optical modules is required to allow control of both installation costs and power savings. + +Replacement of transceivers on a per CP basis should be made possible to enable future technology migrations, either to higher line rates or towards less power-hungry solutions. + +Co-existence with legacy PON is for further study. + +# 7 Service requirements + +WRP should support mobile fronthaul, midhaul and backhaul services as the first step. Support of high-end residential or business services is not precluded. + +Mix-generation antenna sites should be supported. In this context, synchronization enablers including synchronization interfaces are of utmost importance. + +## 7.1 Service specific requirements + +In order to provide the necessary capacity to convey the targeted wireless flow in its entirety, it requires the offering of transparent forwarding with minimal delay and jitter. + +## 7.2 User network interfaces (UNI) + +UNI is defined as the interface that includes the following conditions: + +- Interconnection between the access network and the customer; + +- Described by a well-known standard; +- Includes a physical layer aspect. + +Examples of UNIs, physical interfaces, and the services that they provide are shown in Table 7-1. + +**Table 7-1 – Examples of UNI and services** + +| UNI (Note 1) | Physical interface (Note 2) | Service (Note 3) | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------|------------------------------------------------------| +| 1 Gbit/s /10 Gbit/s /25 Gbit/s
Ethernet
[IEEE 802.3] Copper based UNI | 1000/10G/25G BASE | Ethernet, or Ethernet based
eCPRI (see [b-eCPRI]) | +| 1 Gbit/s/10 Gbit/s/25 Gbit/s
[IEEE 802.3] Fibre based UNI | 1000/10G/25G BASE | Ethernet, or Ethernet based
eCPRI (see [b-eCPRI]) | +| Common public radio interface
(CPRI) / Open base station standard
initiative (OBSAI) | Option2, Option3 Option7,
Option8, Option10 | Wireless fronthaul | +| 1 PPS | 1PPS | Synchronizing interface | +| NOTE 1 – There are many other services accommodated in WDM PON, but those services do not have specified UNIs.
NOTE 2 – Each item in the "Physical interface" column is illustrated by the corresponding entry in the "UNI" column.
NOTE 3 – The column labelled "Service" shows which services can be supported by the physical interface. | | | + +## 7.3 Service node interfaces (SNI) + +SNI is defined as the interface that includes the following conditions: + +- Interconnection between the access network and the service node; +- Described by a well-known standard; +- Includes a physical layer aspect. + +Examples of SNIs, physical interfaces and services that they provide are shown in Table 7-2. + +**Table 7-2 – Examples of SNI and services** + +| SNI
(Note 1) | Physical interface
(Note 2) | Service
(Note 3) | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------|------------------------------------------------------| +| 1 Gbit/s / 10 Gbit/s / 25 Gbit/s
40 Gbit/s / 50 Gbit/s
100 Gbit/s / 200 Gbit/s /
400 Gbit/s – [IEEE 802.3] | 1G/10G/25G/40G/50G/100G/
200G/400G BASE | Ethernet, or Ethernet-based eCPRI
(see [b-eCPRI]) | +| CPRI/OBSAI | Option2, Option3, Option7,
Option8 | | +| NOTE 1 – There are many other services accommodated in WDM PON systems, but those services do not have specified SNIs.
NOTE 2 – Each item in the "Physical interface" column is illustrated by the corresponding entry in the "SNI" column.
NOTE 3 – The column labelled "Service" shows which services can be supported by the physical interface. | | | + +## 7.4 Access node interfaces (ANI) + +Flexible system configurations are required to improve equipment utilisation, reduce power consumption, lower capital expenditure and inventory costs. + +To this end, WRP must support flexible and agnostic interfaces to the optical access network (OAN) to enable the OLT network element to accommodate multiple line rate combinations, and modulation formats by the CT replacement. This objective can be achieved by using pluggable access node interfaces. + +## 7.5 Synchronization and clock transfer + +WRP OLTs for this application must be able to receive a high-quality timing clock as well as to serve as a master timing source for the ONUs. The ONUs must be able to distribute accurate timing/synchronization to cell sites to meet their frequency/phase/time synchronization requirements. + +For this purpose, WRP shall provide a function to transfer the accurate phase/time information between OLT and ONUs while considering the propagation delay and the processing delay between them. Additional inaccuracy incurred in the PON section shall be much less than the reference accuracy to leave margin for other network sections. A summary of the synchronization requirements for different wireless technologies was provided in Table A.II.1 of [ITU-T G.9807.1 Amd. 1]. + +The mechanisms, for instance, as specified in [ITU-T G.8261] and [ITU-T G.8262], for distributing accurate timing to the 3G/4G/5G cell sites are for further study depending on the performance and economics. Given the extra complexity in delivering timing to applications such as mobile backhaul, the additional functionality might be limited to specific "cellular backhaul unit type (CBU)" ONUs. + +Aspects of clock propagation, frequency and time of day synchronization scenarios, and Ethernet synchronization messaging channel (ESMC) messages transport over PON with precision timing protocol [IEEE 1588v2], can be respectively referred to in Appendices A.IV, A.V and A.VI of [ITU-T G.9807.1 Amd. 1]. + +Descriptive information for synchronizing requirements of 5G transport services can be found in [b-ITU-T G.Sup66]. + +# 8 Physical layer requirements + +## 8.1 Capacity + +Generally, WRP should be capable of offering sufficient capacity to enable various services required in clause 7. Besides, the WRP should offer an upgrade to greater line rates without foreseeable technology roadblocks or bottlenecks. + +### 8.1.1 Aggregate capacity at OLT S/R-CG + +A WRP, which operates over multiple wavelength channels, shall be able to support a nominal line rate per wavelength channel of approximately symmetrical 10 Gbit/s or 25 Gbit/s. Within each wavelength channel, the WRP shall support the same requirements with respect to service rate diversity, a full 10 GigE interface, and a full 25 GigE interface. + +### 8.1.2 Capacity at ONU + +A WRP ONU shall be able to support the maximum service rate of approximately 10 Gbit/s or 25 Gbit/s. Note that depending on the target application (e.g., mobile backhaul, mobile fronthaul, etc.) and specific deployment requirements, an ONU may support a lower service rate such as 1 Gbit/s Ethernet, common public radio interface (CPRI) option 3, etc. A WRP ONU is required to offer a 10 Gbit/s or 25 Gbit/s physical interface to the customer. An advanced WRP ONU supporting multiple CPs shall be able to support service rates above/over the maximum service rate for a single channel. + +## 8.2 Support for multiple channel pairs + +Given the various deployment scenarios, a WRP OLT shall be able to support multiple CPs, as shown in Figure 8-1. + +- All integrated, which means all CPs are supported by a complete and integrated array of CTs within an MCT module; +- Grouped, which means CPs are distributed in several MCT modules, and each MCT module comprises of several CTs; +- Individual CT, which means each CP is supported by an independent CT. + +![Figure 8-1: CP integration options. The diagram shows three OLT configurations: a) All integrated, where all OLT CTs (1 to n) are within a single MCT module; b) Grouped, where OLT CTs are distributed across multiple MCT modules (1 to x); c) Individual CT, where each OLT CT (1 to n) is in its own MCT module. All configurations connect to a Wavelength router (AN) via S/R-CP ports, which then connect to an S/R-CG.](7efae06af3af43ffe5d4b956a679cf54_img.jpg) + +a) All integrated + +b) Grouped + +c) Individual CT + +MCT: Multi channel termination module + +G.9802.1(21) + +Figure 8-1: CP integration options. The diagram shows three OLT configurations: a) All integrated, where all OLT CTs (1 to n) are within a single MCT module; b) Grouped, where OLT CTs are distributed across multiple MCT modules (1 to x); c) Individual CT, where each OLT CT (1 to n) is in its own MCT module. All configurations connect to a Wavelength router (AN) via S/R-CP ports, which then connect to an S/R-CG. + +Figure 8-1 – CP integration options + +## 8.3 Wavelength router capability + +The WR in the ODN includes wavelength filters (e.g., arrayed waveguide gratings (AWGs)). At the WR, the ODN branches out to drop fibres, one or several for each ONU. Thus, the ONU's wavelength will be determined by its physical connectivity to the WR in the ODN, e.g., by one port or multi-port on a WR. + +## 8.4 Fibre type and fibre reach + +The system must support using fibre types described in [ITU-T G.652] and [ITU-T G.657]. + +The system must support the maximum fibre distance classes of: + +- 0 to 10 km for wireless applications that are latency sensitive; +- 0 to 20 km for a more general purpose and to match the legacy PON ODN minimal reach. + +# 9 System level requirements + +## 9.1 Pay as you grow expectations + +The WRP enables the addition of ONUs and OLT CT that are not service affecting to traffic flows that are already up and running. + +The replacement of one CT by another combination on the given point-to-point wavelength channel must be individual by conception. + +## 9.2 OLT side modularity + +OLT CTs, unless intended for protection, should be independent from one another, in line rates and modulation format. On a given CP the replacement of one CT by another combination (e.g., line rate) on the CP must be possible individually. + +Given the focus on mobile fronthaul, the OLT design should facilitate multiplexing connectivity (i.e., sum of SNI capacity = sum of ANI capacity). + +Ideally the OLT will be able to individually populate the WRP with OLT CT up to its maximal channel capacity. Hot plug-and-play behaviour is expected. + +However, since implementations of MCT OLT CT can prove more efficient, a granularity of four and upper is envisioned. + +Still in case of such MCT modules, ability to activate them individually and proportionality of power consumption to activated CPs is requested. + +## 9.3 ONU side modularity + +Given the focus on mobile fronthaul, generally there are two ONU design options according to ONU form factor and RU connection mode that needs to be addressed: + +- 1) **Module option:** The ONU is implemented as a pluggable stick supporting only one CP, which is convenient for deployment by plugging it into RU, saving space and minimizing the power supply requirement. In this option, optical penalty and limitation on management channel should be considered. Hot plug-and-play behaviour and dying gasp feature is expected. +- 2) **Device option:** The ONU is a standalone device with one or more CPs, which can serve single or multiple RUs in a site. In case of serving multiple RUs, ability to activate each CP individually is requested. + +## 9.4 Interoperability + +The optical access equipment implemented under the WRP suite of ITU-T Recommendations is expected to be fully interoperable as far as OLT and ONU are concerned, and support open, standards-based interfaces for any external functions. + +## 9.5 Security + +High levels of security are required from WRP especially as they are meant to provide high end users and high-end application traffic. Despite the inherent isolation provided by the WR, physical layer security, secure authentication and an optional encryption method should also be provided. + +# 10 Operational requirements + +## 10.1 Provisioning method + +The provisioning methods for WRP systems will reflect the versatility required by the variety of services to be conveyed. This will specifically have to address the diverse requirements of synchronizing schemes and the necessity to estimate the transmission delay between OLT CT and ONU for any CP. + +Individual provisioning of OLT CT is required to provide a full PAYG capability even in case of OLT CTs implemented in modules containing multiple CTs (aka MCT). + +In order to enable a sanity check of the OLT CT together with the ODN prior to ONU connection, the means to check adequate transmit power and establish an optical path loss measurement must be + +provided. An operation control (OC) message derived from the one described in clause 8.3 of [ITU-T G.9806] is required. + +Since only colourless ONUs will be used over a WR-ODN, automated discovery by both ends under OLT CT initializing is required. + +Authentication methods will be replicated from [BBF TR-156]. + +Management of CGs ending at a same remote site will be provided enabling correlated monitoring and troubleshooting experience. + +## **10.2 Test and diagnostics function** + +The goal of WDM PON supervision is to reduce the operational expenditure of the PON systems, without significantly increasing the capital expenditure by including all necessary test and diagnostic capability in full compatibility with the required bandwidth and time transfer performances required by the targeted services. + +A test and diagnostics function are mandatory to support, and it shall be non-service affecting. Current ITU-T legacy PON's capabilities of basic testing and diagnostics, which operates at the PON and data layers, with reporting back of alarms and events, shall be taken as a basis for WRP. + +## **10.3 System management and monitoring** + +Network operation simplification requires managing the WRP system (i.e., the sum of all CTs together with their respective ONUs), as a single entity, with ONUs being managed via OLTs, wherever possible. Therefore, WRP shall support full PON real-time management through ONU management and control functions. Concepts and approaches implemented for legacy PON (e.g., OMCI) should be reused as much as possible. + +Given the significant effort already expended in defining a converged management framework across optical access systems, ONU management in WRP systems must be based on OMCI ([ITU-T G.988]) suitably augmented with WRP specific MEs. + +The method of conveying physical layer operations, administration and maintenance (PLOAM) and OMCI messaging described in [ITU-T G.9806] will be re-used for Ethernet based transmission. + +For some applications like mobile fronthaul, operations, administration and maintenance (OAM) requirements may focus on optical layer control and supervision, with the dying gasp function for the possible outage event in the emergency case. + +End-to-end performance monitoring enables operators to diagnose and register where customer traffic may have been dropped or throttled. Higher layer tools, such as Ethernet performance monitoring, need to support the capability of monitoring and the verification of ingress and egress traffic flows in PON network elements. + +For services requiring transparent transmission, keeping bitstream integrity, a method to add necessary management information transparently within the tolerance of the service to be conveyed must be supported. + +For the above requirements, a minimum number of OAM signal transmission methods should be defined to avoid the market split. For example, methods to carry the OAM signals can be similar to (1) Transparent AMCC specified in [ITU-T G.989.2], (2) Transcoding AMCC specified in [ITU-T G.989.3], (3) Overcoding AMCC which is to externally apply one of the xByB coding defined in Transcoding AMCC to the binary client signal, and (4) OAM Ethernet frames specified in [ITU-T G.986] and [ITU-T G.9806]. + +Note that the management channel capacity should enable software download without service interruption. + +For dual managed ONUs, the WRP system shall optionally support collaborative ONU management partition between WRP OMCI and remote configuration mechanisms for all types of ONU accommodated. + +## 10.4 System troubleshooting + +The notion of common management of events across CP gathered in logical groups is expected to help per remote site troubleshooting. + +PON systems with their monitoring and control systems will allow operators to decide on the utilization of proactive or reactive fault repairs in most fault cases. It is of course up to the operators to decide how to use PON status reports. + +## 10.5 Environmental and physical requirements + +Outdoor operation may be needed in many of the envisaged applications for WRP systems; thus, ONUs shall operate over outdoor temperature ranges. The following are informative examples of environmental requirements: + +- ATIS-0600010.01.2008: (Class 4 unprotected environment) +*–40°C to either +46°C ambient plus solar loading, or +70°C ambient* +- Telcordia GR-487 +*–40°C to either +46°C ambient plus solar loading, or +70°C ambient* +- ETSI ETS 300 019-1-4: (Class 4.1E: Non-weather protected locations – extended) +*–45°C to +45°C ambient plus solar loading* + +Optionally, the OLT should also be able to operate over the extended outside temperature range. + +## 10.6 Energy saving objectives + +The ultimate target of energy efficiency should be that zero payload is to be conveyed equals zero power consumed and that power consumption per channel is proportional to the payload to be conveyed. + +Following the PAYG principle, an OLT CT that hasn't been logically provisioned should induce no power consumption. As long as no ONU is responding on the CT's CP, the power consumption of the OLT CT should remain negligible. + +Even in the case of OLT CTMCT, the individual power up/down function of the OLT CT is required. + +WRP systems will provide the best user and network energy efficiency experience combining sleep periods behaviours when the link is idle. + +Power saving mechanisms are required and mechanisms including ITU-T PON sleep modes and line rate switching during low duty periods will be considered. Necessary adjustments can be tailored to the actual payload to be conveyed. + +## 10.7 Eye safety + +All necessary mechanisms must be provided to ensure that no eye damage can be caused to field operations in case of crews unaware of the risks associated with access to fibre, including labelling and safety locking mechanisms if necessary. The system must meet all applicable requirements for the classification, service group designation, and accessibility to ensure the safe operation and servicing of the optical fibre communication system at each node. Since the WRP features a multiplicity of CPs in the feeder section, the total optical power resulting from one CT at send/receive reference point at OLT side (S/R)-CP and the sum of all the wavelengths at S/R-CG on the fibre must be within the safe operation range. + +The WRP network elements need to conform to the following specific classes defined in [IEC 60825-2], respectively: + +- Class 1M for OLT, +- Class 1 for ONU, +- Class 1M for RE. + +# 11 Resilience and protection on ODN + +Mechanisms required for operation over a WR-ODN should be made compatible as much as possible with operation over optical (achromatic) power splitter (OPS) (e.g., as per ITU-T G.989.1 principles). This will enable network elements to be made compatible at logical level for chipsets. + +## 11.1 Rogue behaviour prevention, detection and mitigation + +Given the optical access legacy of ONUs designed for PON or point to point BiDi transmission implementing silent start behaviour, reciprocal non harming behaviour is required: + +- ONU transmission can only start after recognition of an explicit request to transmit received from an OLT CT; +- As WDM PON local framing is optional and no bandwidth map is provided, ONU identification is still useful for management, indicating that the channel is idle and must be secured: + - On the ONU side, recognition of an explicit message indicates that the associated upstream wavelength associated to the downstream wavelength to constitute a CP must be provided by the OLT; + - From the upstream direction signal, the OLT CT must secure that if transmitting, it does not collide with an already transmitting parallel OLT CT operating on the same wavelength. Such situations that could occur in certain protection schemes have to be prevented. +- Means to prevent misinterpretation between sleeping periods and idle status must be provided. So silent start timers must exceed the maximal sleep period to cover at least one wake-up sequence. + +## 11.2 CT failure protection + +Given the nature of the WR-ODN WDM PON architecture, since using the same CP, CT protection is equivalent to the corresponding ONU protection as shown in Figure 11-1 with a specific WR structure in which an OPS function is embedded. + +Design options of the WR boxes in the following figures are for further study. + +Similarly, usage of a tunable single protection CT will require an introduction of an OPS in Figure 11-2. + +![Figure 11-1: Example of full CT protection. This diagram shows a 'Central office' containing two groups of OLT CTs: 'Main OLT CTs' (OLT CT-1 to OLT CT-n) and 'Protection OLT CTs' (OLT CT-1 to OLT CT-n). Each CT is connected to a 'Wavelength router (AN)' via a specific S/R-CP (e.g., S/R-CP1 to S/R-CPn). The Wavelength router (AN) is connected via an optical fiber (indicated by two circles) to another 'Wavelength router (ODN)'. The Wavelength router (ODN) is connected to multiple ONUs (ONU-1, ONU-2, ONU-x) at their UNIs. The ODN has an R/S interface on the left and a UNI interface on the right. A reference label 'G.9802.1(21)' is in the bottom right.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +Figure 11-1: Example of full CT protection. This diagram shows a 'Central office' containing two groups of OLT CTs: 'Main OLT CTs' (OLT CT-1 to OLT CT-n) and 'Protection OLT CTs' (OLT CT-1 to OLT CT-n). Each CT is connected to a 'Wavelength router (AN)' via a specific S/R-CP (e.g., S/R-CP1 to S/R-CPn). The Wavelength router (AN) is connected via an optical fiber (indicated by two circles) to another 'Wavelength router (ODN)'. The Wavelength router (ODN) is connected to multiple ONUs (ONU-1, ONU-2, ONU-x) at their UNIs. The ODN has an R/S interface on the left and a UNI interface on the right. A reference label 'G.9802.1(21)' is in the bottom right. + +**Figure 11-1 – Example of full CT protection** + +![Figure 11-2: Example of individual CT protection through an OPS and a tunable CT. This diagram shows a 'Central office' with 'Main OLT CTs' (OLT CT-1 to OLT CT-n) connected to a 'Wavelength router (AN)'. A 'Protection via a tunable CT' (OLT CT-x) is also connected to the Wavelength router (AN). The Wavelength router (AN) is connected to an 'OPS' (Optical Protection Switch), which is then connected via an optical fiber to a 'Wavelength router (ODN)'. The Wavelength router (ODN) connects to ONUs (ONU-1, ONU-2, ONU-x) at their UNIs. An 'ICTP interface' is shown on the left side of the Main OLT CTs. Reference labels 'G.9802.1(21)' are in the bottom right.](5445597cceefaca1ac89e710fe339325_img.jpg) + +Figure 11-2: Example of individual CT protection through an OPS and a tunable CT. This diagram shows a 'Central office' with 'Main OLT CTs' (OLT CT-1 to OLT CT-n) connected to a 'Wavelength router (AN)'. A 'Protection via a tunable CT' (OLT CT-x) is also connected to the Wavelength router (AN). The Wavelength router (AN) is connected to an 'OPS' (Optical Protection Switch), which is then connected via an optical fiber to a 'Wavelength router (ODN)'. The Wavelength router (ODN) connects to ONUs (ONU-1, ONU-2, ONU-x) at their UNIs. An 'ICTP interface' is shown on the left side of the Main OLT CTs. Reference labels 'G.9802.1(21)' are in the bottom right. + +**Figure 11-2 – Example of individual CT protection through an OPS and a tunable CT** + +In case of concurrent OLT CT operation on a given CP, special care must be taken to coordinate the OLT CTs. + +Even if inter channel termination protocol (ICTP) (See [b-BBF TR-352]) is used, each OLT CT must implement a silent start behaviour to prevent any collision. + +## 11.3 ODN failure protection + +Protection of the feeder section with single attachment in Figure 11-3 or through a redundant OLT located in the same CO or through dual attachment in Figure 11-4. + +Details of the necessary structure of local and remote feeder protection enabling WRs or additional devices are for further study and impact on an optical budget should be kept minimal. + +![Figure 11-3: Example of feeder protection through single OLT through an external optical switch. The diagram shows a Central office containing OLT CTs (OLT CT-1 to OLT CT-n) connected to S/R-CP1 to S/R-CPn, which are then connected to a Wavelength router (AN). A Control IF is also present. The Wavelength router (AN) is connected to an external optical switch (K). The optical switch is connected to a Wavelength router (ODN), which is connected to UNIs (ONU-1, ONU-2, ONU-x) via R/S interfaces. The SNI interface is also shown.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +The diagram illustrates a single OLT configuration for feeder protection. Inside a 'Central office', multiple 'OLT CTs' (OLT CT-1, OLT CT-2, OLT CT-3, OLT CT-n) are connected to corresponding 'S/R-CP' units (S/R-CP1, S/R-CP2, S/R-CP3, S/R-CPn). These units are connected to a 'Wavelength router (AN)'. A 'Control IF' is also connected to this router. The 'Wavelength router (AN)' is connected to an external optical switch labeled 'K'. The optical switch is connected to a 'Wavelength router (ODN)'. The 'Wavelength router (ODN)' is connected to three 'ONU' units (ONU-1, ONU-2, ONU-x) at their 'UNI' interfaces. The 'R/S' (Restoration Switch) interface is shown between the 'Wavelength router (ODN)' and the 'UNIs'. The 'SNI' (Service Network Interface) is shown on the left side of the 'Central office'. + +Figure 11-3: Example of feeder protection through single OLT through an external optical switch. The diagram shows a Central office containing OLT CTs (OLT CT-1 to OLT CT-n) connected to S/R-CP1 to S/R-CPn, which are then connected to a Wavelength router (AN). A Control IF is also present. The Wavelength router (AN) is connected to an external optical switch (K). The optical switch is connected to a Wavelength router (ODN), which is connected to UNIs (ONU-1, ONU-2, ONU-x) via R/S interfaces. The SNI interface is also shown. + +**Figure 11-3 – Example of feeder protection through single OLT through an external optical switch** + +![Figure 11-4: Example of feeder protection through dual OLT. The diagram shows two sets of OLT CTs: 'Main OLT CTs' and 'Protection OLT CTs'. Each set contains OLT CT-1 to OLT CT-n connected to S/R-CP1 to S/R-CPn, which are then connected to a Wavelength router (AN). Both Wavelength routers (AN) are connected to a common Wavelength router (ODN), which is connected to UNIs (ONU-1, ONU-2, ONU-x) via R/S interfaces. The SNI interface is also shown.](c5655e700cc3e9aac7e9f4f07f30264d_img.jpg) + +The diagram illustrates a dual OLT configuration for feeder protection. It features two sets of 'OLT CTs': 'Main OLT CTs' and 'Protection OLT CTs'. Each set contains 'OLT CT-1', 'OLT CT-2', 'OLT CT-3', and 'OLT CT-n' connected to 'S/R-CP1', 'S/R-CP2', 'S/R-CP3', and 'S/R-CPn' respectively. These are connected to individual 'Wavelength router (AN)' units. Both 'Wavelength router (AN)' units are connected to a common 'Wavelength router (ODN)'. The 'Wavelength router (ODN)' is connected to three 'ONU' units (ONU-1, ONU-2, ONU-x) at their 'UNI' interfaces. The 'R/S' (Restoration Switch) interface is shown between the 'Wavelength router (ODN)' and the 'UNIs'. The 'SNI' (Service Network Interface) is shown on the left side of the 'Main OLT CTs' and 'Protection OLT CTs' blocks. + +Figure 11-4: Example of feeder protection through dual OLT. The diagram shows two sets of OLT CTs: 'Main OLT CTs' and 'Protection OLT CTs'. Each set contains OLT CT-1 to OLT CT-n connected to S/R-CP1 to S/R-CPn, which are then connected to a Wavelength router (AN). Both Wavelength routers (AN) are connected to a common Wavelength router (ODN), which is connected to UNIs (ONU-1, ONU-2, ONU-x) via R/S interfaces. The SNI interface is also shown. + +**Figure 11-4 – Example of feeder protection through dual OLT** + +## Bibliography + +- [b-ITU-T G.Sup66] ITU-T G Sup. 66 (2020), *5G wireless fronthaul requirements in a passive optical network context.* +- [b-BBF TR-352] Broadband Forum Technical Report BBF TR-352, Issue 2 (2020), *Multi-wavelength PON Inter-Channel-Termination Protocol (ICTP) Specification.* +- [b-eCPRI] eCPRI Specification V2.0 (2019), *Common Public Radio Interface: eCPRI Interface Specification.* +- [b-OBSAI] OBSAI Open Base Station Architecture Initiative (2006), *BTS system reference document V2.0.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9807.2-201708-I_PDF-E/raw.md b/marked/G/T-REC-G.9807.2-201708-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..0d85adfd182d1403a153d5da1774815ffd468c87 --- /dev/null +++ b/marked/G/T-REC-G.9807.2-201708-I_PDF-E/raw.md @@ -0,0 +1,1193 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9807.2** + +(08/2017) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – Optical line systems for local and +access networks + +--- + +**10 Gigabit-capable passive optical networks +(XG(S)-PON): Reach extension** + +Recommendation ITU-T G.9807.2 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9807.2 + +# 10 Gigabit-capable passive optical networks (XG(S)-PON): Reach extension + +## Summary + +Recommendation ITU-T G.9807.2 outlines the architecture and interface parameters for 10 gigabit-capable symmetric passive optical network (XG(S)-PON) systems with extended reach using a physical layer reach extension device, such as a regenerator or optical amplifier in the fibre link between the optical line termination (OLT) and optical network unit (ONU). Wavelength converting, continuous mode, 1:N and combination type reach extenders (REs) are also described. The maximum reach is up to 60 km with loss budgets in excess of 28.5 dB being achievable in both spans. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.9807.2 | 2017-08-13 | 15 | 11.1002/1000/13294 | + +## Keywords + +Reach extender; XG(S)-PON. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2017 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | | Page | +|--------------|---------------------------------------------------------------------------------------------|------| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Conventions ..... | 3 | +| 6 | Optical extension schemes and architectures ..... | 3 | +| 6.1 | OA-based reach extenders ..... | 7 | +| 6.2 | OEO-based reach extenders ..... | 8 | +| 6.3 | Hybrid architectures ..... | 10 | +| 6.4 | Wavelength conversion reach extenders ..... | 12 | +| 6.5 | Wavelength re-conversion at OLT ..... | 13 | +| 6.6 | Combination G-PON and XG(S)-PON reach extenders ..... | 14 | +| 6.7 | Increased fanout reach extenders..... | 16 | +| 7 | General requirements for XG(S)-PON reach extenders ..... | 17 | +| 7.1 | Compatibility..... | 17 | +| 7.2 | Management ..... | 18 | +| 7.3 | Power ..... | 20 | +| 7.4 | Optional enhancements ..... | 20 | +| 8 | Specifications for mid-span extenders ..... | 20 | +| 8.1 | Optical trunk line ..... | 20 | +| 8.2 | Optical trunk line interface (R'/S') and OLT interface (S/R)..... | 21 | +| 8.3 | Optical distribution network..... | 24 | +| 8.4 | Extender interface to optical distribution network (S'/R') and ONU
interface (R/S) ..... | 24 | +| 8.5 | TC layer impacts..... | 26 | +| 8.6 | WDM wavelength allocation plan for OTL ..... | 27 | +| Appendix I | – Implications on OLT receivers due to insertion of OA type extenders ..... | 29 | +| Appendix II | – Protection..... | 31 | +| II.1 | Introduction ..... | 31 | +| II.2 | RE-independent type B protection ..... | 31 | +| II.3 | OEO extender-based type B protection..... | 31 | +| II.4 | OA-extender-based type B protection architecture ..... | 32 | +| Appendix III | – Optical time domain reflectometer..... | 33 | +| III.1 | Introduction ..... | 33 | +| III.2 | Solution..... | 33 | +| Appendix IV | – Transport of BM-to-CM converted signals over OTN ..... | 34 | +| Appendix V | – Possible realization of OA and OEO-based extenders using wavelength
conversion..... | 35 | + +| | Page | +|--------------------------------------------------------------|-------------| +| V.1 A transparent wavelength plan extender realization..... | 35 | +| V.2 A conventional wavelength plan extender realization..... | 36 | +| V.3 An OWC based extender realization ..... | 38 | +| Bibliography..... | 40 | + +# 10 Gigabit-capable passive optical networks (XG(S)-PON): Reach extension + +# 1 Scope + +This Recommendation concerns 10 gigabit-capable symmetric passive optical network (XG(S)-PON) systems with optical link budgets up to the logical limits of the transmission convergence (TC) layer. It extends the capabilities of [b-ITU-T G.987.4], limited to asymmetric XG-PON, to XG(S)-PON, including its dual rate working capacity. The increased optical capability, which includes both increased overall fibre length and increased overall splitting ratio, is referred to in this Recommendation as "reach extension". The primary concerns addressed are the increase of the loss budget and the management of optical impairments. + +This Recommendation considers mid-span extension, which uses an active extension node placed in the middle of the optical network. The recommended parameters for the optical distribution network(s) [ODN(s)] involved in this scheme are specified. Single-sided extension is considered as an improvement to the optical line terminal (OLT) interface. + +The systems considered here must remain compatible with existing optical network units (ONUs). Furthermore, the approaches should maintain compatibility with existing OLTs to the maximum extent possible. It is recognized that some modification of the OLT equipment may be necessary, but this should be minimized. + +Two system architectures are considered: optical amplification and opto-electronic regeneration. These can be viewed as providing reach extension at the physical layer. The key interfaces and functional blocks in each of these architectures are identified and specified. + +Optionally, optical-electronic-optical (OEO) type reach extender (RE) units may support a burst mode (BM) to continuous mode (CM) conversion function, as specified in clause 6.2. In this case, it is also necessary to introduce a CM to BM conversion function before the S/R interface at the OLT. + +Optionally, both optical amplifier (OA) and OEO type RE units may support the wavelength conversion (WC) function, as specified in clause 6.4. In case of WC-enabled RE units, it is also necessary to introduce a WC-function block before the S/R interface. + +Optionally, combination RE units may support all the functions described in this Recommendation, and the G-PON RE functions described in [ITU-T G.984.6]. + +The optional support of a type B protection in RE units is described. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +[ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*. + +[ITU-T G.984.5] Recommendation ITU-T G.984.5 (2014), *Gigabit-capable passive optical networks (G-PON): Enhancement band*. + +- [ITU-T G.984.6] Recommendation ITU-T G.984.6 (2008), *Gigabit-capable passive optical networks (GPON): Reach extension.* +- [ITU-T G.987.2] Recommendation ITU-T G.987.2 (2016), *10 Gigabit-capable passive optical networks (XG-PON): Physical media dependent (PMD) layer specification.* +- [ITU-T G.987.3] Recommendation ITU-T G.987.3 (2014), *10 Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification.* +- [ITU-T G.988] Recommendation ITU-T G.988 (2012), *ONU management and control interface (OMCI) specification.* +- [ITU-T G.694.1] Recommendation ITU-T G.694.1 (2012), *Spectral grids for WDM applications: DWDM frequency grid.* +- [ITU-T G.694.2] Recommendation ITU-T G.694.2 (2003), *Spectral grids for WDM applications: CWDM wavelength grid.* +- [ITU-T G.9807.1] Recommendation ITU-T G.9807.1 (2016), *10-Gigabit-capable symmetric passive optical network (XGS-PON).* +- [ITU-T L.313] Recommendation ITU-T L.313/L.66 (2007), *Optical fibre cable maintenance criteria for in-service fibre testing in access networks.* + +# 3 Definitions + +See clause 3 of [ITU-T G.9807.1]. + +## 4 Abbreviations and acronyms + +See clause 4 of [ITU-T G.9807.1] in addition to the following. + +| | | +|-----------|--------------------------------------------------------| +| 2R | Re-amplification, Reshaping | +| AOWC | All-Optical Wavelength Converter | +| ASE | Amplified Spontaneous Emission | +| BM | Burst Mode | +| CM | Continuous Mode | +| EONU | Embedded Optical Network Unit | +| LC | Local Controller | +| MCR | Mode-Coupling Receiver | +| OA | Optical Amplifier | +| OBF | Optical Bandpass Filter | +| OEO | Optical-Electronic-Optical | +| SOA | Semiconductor Optical Amplifier | +| WC | Wavelength Conversion | +| WLCH | Wavelength Channel | +| XGM | cross-Gain Modulation | +| XGS-PON | 10-Gigabit-capable Symmetric Passive Optical Network | +| XG(S)-PON | 10 Gigabit-capable (Symmetric) Passive Optical Network | + +# 5 Conventions + +See clause 5 of [ITU-T G.9807.1]. + +# 6 Optical extension schemes and architectures + +The basic PON architecture is shown in Figure 1. The OLT interfaces with multiple ONUs via the ODN. The OLT also provides interfaces to one or more service node interfaces (SNIs), as well as the management system. The ONU interfaces with various UNIs. The only interfaces of interest to this Recommendation are those that face the ODN. The XGS-PON physical medium dependent (PMD) specification (see Annex B of [ITU-T G.9807.1]) specifies the loss profile for the ODN to be 14~9 dB, 16~31 dB, 18~33 dB or 20~35 dB. The OLT-ODN and ONU-ODN interfaces for XGS-PON are specified in Annex B of [ITU-T G.9807.1]. Indeed, most ITU-compliant PONs deployed today adhere to these Recommendations. + +![Figure 1 – Basic PON architecture diagram](7a0db9703b68b3d06cdaeefc084c0006_img.jpg) + +The diagram illustrates the basic PON architecture. On the left, two ONUs are shown, each connected to a UNI. Each ONU is connected to an ODN via an R/S interface. The ODN is connected to an OTL via an S/R interface. The OTL is connected to an SNI. The diagram is labeled G.9807.2(17)\_F01. + +Figure 1 – Basic PON architecture diagram + +**Figure 1 – Basic PON architecture** + +The architecture considered in this Recommendation is illustrated in Figure 2. A mid-span extender device is inserted between the ODN (compliant with existing PON Recommendations) and an optical trunk line (OTL), which is connected to the OLT. This architecture extends the reach of the PON by the length of the OTL, and may also increase the split ratio of the PON. However, it does require electrical power for the mid-span extender. + +Since XG(S)-PON from the start enables the co-working of XG-PON and XGS-PON ONUs, dual rate operation for the upstream is mandatory. + +![Figure 2 – Mid-span reach extension diagram](a234352dfaccdc24745c88eef7724cc6_img.jpg) + +The diagram illustrates the mid-span reach extension architecture. On the left, two ONUs are shown, each connected to a UNI. Each ONU is connected to an ODN via an R/S interface. The ODN is connected to a Mid-span extender via an S'/R' interface. The Mid-span extender is connected to an OTL via an R'/S' interface. The OTL is connected to another OTL via an S/R interface. The second OTL is connected to an SNI. The diagram is labeled G.9807.2(17)\_F02. + +Figure 2 – Mid-span reach extension diagram + +**Figure 2 – Mid-span reach extension** + +An extended architecture considered in this Recommendation is presented in Figure 3. A WC-enabled RE-unit is inserted between the ODN (compliant with existing PON recommendations) and an optical trunk line (OTL), which is connected to the OLT. This architecture extends the reach of the PON by the length of the OTL, and may also increase the split ratio of the PON. Additionally, the WC-RE unit may aggregate several XGS-PON-class ODNs, enabled by the WDM over OTL to achieve more cost-efficient use of existing fibre infrastructure. The WC function block inserted before the S/R interface at the OLT performs adaptation between the WDM optical signals transmitted over the OTL and the OLT interfaces that are compliant with ITU-T G.9807-series Recommendations. + +![Figure 3: Wavelength conversion reach extender architecture. The diagram shows four ONUs connected to two ODNs. Each ODN is connected to a 'WC + RE' block via S'/R' interfaces. The 'WC + RE' block is connected to an 'OTL' via R''/S'' and S''/R'' interfaces. This 'OTL' is connected to a 'WC' block. The 'WC' block is connected to two 'OTL' blocks via S/R interfaces. Each 'OTL' block is connected to an SNI. The diagram is labeled G.9807.2(17)_F03.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Figure 3: Wavelength conversion reach extender architecture. The diagram shows four ONUs connected to two ODNs. Each ODN is connected to a 'WC + RE' block via S'/R' interfaces. The 'WC + RE' block is connected to an 'OTL' via R''/S'' and S''/R'' interfaces. This 'OTL' is connected to a 'WC' block. The 'WC' block is connected to two 'OTL' blocks via S/R interfaces. Each 'OTL' block is connected to an SNI. The diagram is labeled G.9807.2(17)\_F03. + +**Figure 3 – Wavelength conversion reach extender architecture** + +An additional extended architecture considered in this architecture is shown in Figure 4. "BM-to-CM" means burst mode to continuous mode converter, and *vice versa*. A BM-to-CM converter is used at the remote PON RE to convert the bursty upstream signal into a conventional continuous mode signal. A CM-to-BM converter is theoretically present at the OLT location, although it will most likely be integrated into the OLT itself. + +![Figure 4: BM-to-CM conversion reach extender architecture. The diagram shows two ONUs connected to an ODN. The ODN is connected to a 'BM to CM RE' block via S'/R' interfaces. The 'BM to CM RE' block is connected to an 'OTL' via R''/S'' and S''/R'' interfaces. This 'OTL' is connected to a 'CM to BM' block. The 'CM to BM' block is connected to an 'OTL' via S/R interfaces. This 'OTL' is connected to an SNI. The diagram is labeled G.9807.2(17)_F04.](e6df2733626a85205c1db682e6259c46_img.jpg) + +Figure 4: BM-to-CM conversion reach extender architecture. The diagram shows two ONUs connected to an ODN. The ODN is connected to a 'BM to CM RE' block via S'/R' interfaces. The 'BM to CM RE' block is connected to an 'OTL' via R''/S'' and S''/R'' interfaces. This 'OTL' is connected to a 'CM to BM' block. The 'CM to BM' block is connected to an 'OTL' via S/R interfaces. This 'OTL' is connected to an SNI. The diagram is labeled G.9807.2(17)\_F04. + +**Figure 4 – BM-to-CM conversion reach extender architecture** + +An additional aspect of XG(S)-PON systems is their coexistence with the ITU-T G.984-series G-PON systems. The RE function can be combined to support both systems simultaneously, as shown in Figure 5. The "combo" RE fulfils the roles of both an ITU-T G.984.6 RE and an RE compliant with this Recommendation. + +Furthermore, since XG(S)-PON systems can optionally also operate at the wavelength of G-PON that is defined under the name of "optional wavelength set", the combo REs would see 10 Gbit/s working on both wavelength pairs. + +![Figure 5(a): Combination G-PON/XG(S)-PON reach extender. The diagram shows three ONUs (G-PON ONU, XG-PON ONU, and XGS-PON ONU) connected to an ODN. The ODN is connected to a 'Combo RE' block via S'/R' interfaces. The 'Combo RE' block is connected to an 'OTL' via R'/S' interfaces. This 'OTL' is connected to a 'WDM1r' block. The 'WDM1r' block is connected to two 'OTL' blocks via S/R interfaces. The top 'OTL' block is connected to a G-PON OTL, which is connected to an SNI. The bottom 'OTL' block is connected to an XG(S)-PON OTL, which is connected to an SNI. The diagram is labeled G.9807.2(17)_F05a.](c2fc2621e8206d24427b56bcb2398fc0_img.jpg) + +Figure 5(a): Combination G-PON/XG(S)-PON reach extender. The diagram shows three ONUs (G-PON ONU, XG-PON ONU, and XGS-PON ONU) connected to an ODN. The ODN is connected to a 'Combo RE' block via S'/R' interfaces. The 'Combo RE' block is connected to an 'OTL' via R'/S' interfaces. This 'OTL' is connected to a 'WDM1r' block. The 'WDM1r' block is connected to two 'OTL' blocks via S/R interfaces. The top 'OTL' block is connected to a G-PON OTL, which is connected to an SNI. The bottom 'OTL' block is connected to an XG(S)-PON OTL, which is connected to an SNI. The diagram is labeled G.9807.2(17)\_F05a. + +**Figure 5(a) – Combination G-PON/XG(S)-PON reach extender** + +![Figure 5(b) – Combination XG(S)-PON/XGS-PON reach extender diagram. On the left, two ONUs (XG(S)-PON ONU and XGS-PON ONU) are connected to a central ODN. The ODN has R/S interfaces for the ONUs and an S'/R' interface connected to a 'Combo RE'. The 'Combo RE' has an R'/S' interface connected to an 'OTL', which in turn connects to a 'WDM1r'. The 'WDM1r' has two S/R interfaces connected to two ONTs (XG(S)-PON OTL and XGS-PON OTL), which are then connected to SNIs. The diagram is labeled G.9807.2(17)_F05b.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Figure 5(b) – Combination XG(S)-PON/XGS-PON reach extender diagram. On the left, two ONUs (XG(S)-PON ONU and XGS-PON ONU) are connected to a central ODN. The ODN has R/S interfaces for the ONUs and an S'/R' interface connected to a 'Combo RE'. The 'Combo RE' has an R'/S' interface connected to an 'OTL', which in turn connects to a 'WDM1r'. The 'WDM1r' has two S/R interfaces connected to two ONTs (XG(S)-PON OTL and XGS-PON OTL), which are then connected to SNIs. The diagram is labeled G.9807.2(17)\_F05b. + +**Figure 5(b) – Combination XG(S)-PON/XGS-PON reach extender** + +NOTE – In Figure 5(b), the combination of the XG(S)-PON and XGS-PON devices is enabled by the use of XGS-PON devices at the optional wavelength set in addition to XG(S)-PON devices operating at the basic wavelength set. + +REs can also incorporate additional fanout within the RE, as shown in Figure 6. In this case, the RE has multiple S'/R' interfaces that are combined with the usual PON logical connectivity (downstream broadcast, upstream combining) to a single R'/S' interface. However, it is not the same as placing a splitter next to the RE, as the loss budget constraints would prevent this. A couple of physical methods to achieve this are described in clause 6.7. The motivation for such a scheme is to increase the sharing of the OLT port, OTL fibre and RE R'/S' interface over more ODNs. This can be particularly useful in the XG(S)-PON overlay application. + +![Figure 6 – Reach extender with additional fanout in the RE diagram. Four ONUs are connected to two separate ODNs. Each ODN has an S'/R' interface connected to a large 'RE + split' block. The 'RE + split' block has a single R'/S' interface connected to an 'OTL', which connects to another 'OTL' block, which then connects to an SNI. The diagram is labeled G.9807.2(17)_F06.](d26959f4514c26ca19c3d6f00da85956_img.jpg) + +Figure 6 – Reach extender with additional fanout in the RE diagram. Four ONUs are connected to two separate ODNs. Each ODN has an S'/R' interface connected to a large 'RE + split' block. The 'RE + split' block has a single R'/S' interface connected to an 'OTL', which connects to another 'OTL' block, which then connects to an SNI. The diagram is labeled G.9807.2(17)\_F06. + +**Figure 6 – Reach extender with additional fanout in the RE** + +The topology of REs is to allow point-to-multipoint connectivity between the RE and the OLT, as shown in Figure 7. In this case, the split optical trunk line (S-OTL) contains some passive that combines the output of several R'/S' interfaces into a single S/R interface to the OLT. The motivation here is similar to the previous case: to increase the sharing of the OLT interface. This method also allows for physically diverse placement of the subtending RE units. However, it does not increase the sharing of the RE R'/S' interfaces, and it then requires that the R'/S' interfaces must be able to operate in burst mode. + +![Figure 7: Reach extender with a split optical trunk line. The diagram shows four ONUs connected to two ODNs. Each ODN is connected to an RE. Both REs are connected to a central S-OTL, which is further connected to an OTL and an SNI. Interfaces are labeled UNI, R/S, S'/R', R'/S', and S/R.](d4af765160d04ecef538e5066006dc77_img.jpg) + +G.9807.2(17)\_F07 + +Figure 7: Reach extender with a split optical trunk line. The diagram shows four ONUs connected to two ODNs. Each ODN is connected to an RE. Both REs are connected to a central S-OTL, which is further connected to an OTL and an SNI. Interfaces are labeled UNI, R/S, S'/R', R'/S', and S/R. + +**Figure 7 – Reach extender with a split optical trunk line** + +There are several ways to implement an optical RE. There are two general classes of extenders. The first is an optical amplifier (OA), shown in Figure 8a), which provides gain in optical power. The second is an OEO regenerator [Figure 8b)], which receives an optical signal, reshapes and retimes it in the electrical domain, and retransmits in the optical domain. Further hybrid schemes are possible, for example, to use optical amplification in the downstream and regeneration in the upstream, as shown in Figure 9a) or the reverse as shown in Figure 9b). + +![Figure 8: The two basic extender architectures. (a) Optical amplifier architecture showing two Diplexers connected by two parallel paths, each containing an OA and an optional OBF. (b) Repeater architecture showing two Diplexers connected to a central unit with Rx, Tx, and Clock components. Interfaces are labeled S'/R' and R'/S'.](27b06ec9f42b5d727a2630f61a5f1861_img.jpg) + +G.9807.2(17)\_F08 + +Figure 8: The two basic extender architectures. (a) Optical amplifier architecture showing two Diplexers connected by two parallel paths, each containing an OA and an optional OBF. (b) Repeater architecture showing two Diplexers connected to a central unit with Rx, Tx, and Clock components. Interfaces are labeled S'/R' and R'/S'. + +**Figure 8 – The two basic extender architectures: Optical amplifier, repeater** + +![Figure 9: Examples for hybrid extender architectures. Diagram (a) shows a bidirectional path. The top path goes from a Diplexer through an Rx to a Tx and then to another Diplexer. The bottom path goes from the first Diplexer through an optional OBF and an OA to the second Diplexer. Diagram (b) shows a similar setup but with the OA and optional OBF on the top path, and a Tx, Rx, and Clock on the bottom path. Interfaces are labeled S'/R' and R'/S'.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +a) + +b) + +OA Optical amplifier +OBF Optical bandpass filter + +G.9807.2(17)\_F09 + +Figure 9: Examples for hybrid extender architectures. Diagram (a) shows a bidirectional path. The top path goes from a Diplexer through an Rx to a Tx and then to another Diplexer. The bottom path goes from the first Diplexer through an optional OBF and an OA to the second Diplexer. Diagram (b) shows a similar setup but with the OA and optional OBF on the top path, and a Tx, Rx, and Clock on the bottom path. Interfaces are labeled S'/R' and R'/S'. + +**Figure 9 – Examples for hybrid extender architectures** + +## 6.1 OA-based reach extenders + +REs based on optical amplifiers optionally may include optical bandpass filters (OBFs) in order to restrict the bandwidth of amplified spontaneous emission (ASE) generated by the optical amplifier, and thus reduce ASE-ASE beat noise and ASE-based power-offset (see Appendix I) in the optical receiver and achieve higher performance. + +Due to the nature of OA-based REs, the application range (useable trunk and ODN loss range) varies according to the parameters of the optical amplifiers used. The vendor has to provide sufficient data showing the key parameters (e.g., maximum gain, minimum gain, and saturated output power), the application range and applicable penalties due to ASE. + +As there is no signal regeneration provided by OA-based REs, ONU and OLT transmitters must provide a dispersion reach of up to 60 km. + +An optical amplifier-based extender should include a complete embedded ONU (EONU) for management purposes, as shown in Figure 10. The EONU is connected internally by means of an optical tap coupler at the interface facing the OTL in order to keep the RE accessible, even if an optical amplifier fails. + +![Figure 10: OA-type reach extender with embedded ONU for management purposes. A dashed box contains an Upstream amplifier and a Downstream amplifier connected between two Diplexers. A tap coupler on the right side (R'/S' interface) connects to the EONU, which is linked to a Local controller. The Local controller has control lines to both amplifiers. Interfaces are labeled S'/R' and R'/S'.](3ad00ce93ad9dea9ee0f47535e5355e6_img.jpg) + +G.9807.2(17)\_F10 + +Figure 10: OA-type reach extender with embedded ONU for management purposes. A dashed box contains an Upstream amplifier and a Downstream amplifier connected between two Diplexers. A tap coupler on the right side (R'/S' interface) connects to the EONU, which is linked to a Local controller. The Local controller has control lines to both amplifiers. Interfaces are labeled S'/R' and R'/S'. + +**Figure 10 – OA-type reach extender with embedded ONU +for management purposes** + +## 6.2 OEO-based reach extenders + +The signals passing through the OEO extender are re-timed (2R regenerators are not specified by this Recommendation). The timing reference for this function is the downstream receiver of the extender (see Figure 11). This timing is used to drive both transmitters and as a reference for the other receiver. This arrangement is identical to that used in SDH regenerator devices. + +The presence of an OEO-based extender may require extension of burst overhead, which is automatically handled by the OLT via physical layer operations, administration and maintenance (PLOAM) messages (refer to clause 8.5). As the increase of burst overhead is bandwidth relevant, upstream burst detection is supported by the aid of an EONU (see Figure 11) which is used for management (see clause 7.2). In addition to the managing functions, the EONU may analyse the downstream signal and read the BW map in order to calculate burst-timing. In this way, a reset signal to the upstream burst-mode receiver can be provided and the required burst overhead extension is kept to a minimum. + +![Figure 11: OEO-type reach extender with EONU for management purposes. The diagram shows a dashed box containing a Diplexer, RX, TX, EONU, and a Local controller. The left side has an S'/R' interface connected to a Diplexer. The Diplexer is connected to an RX and a TX. The RX is connected to the EONU and a clock (clk). The TX is connected to the EONU and a clock (clk). The EONU is connected to the Local controller. The right side has a Diplexer connected to an RX and a TX. The RX is connected to the EONU and a clock (clk). The TX is connected to the EONU and a clock (clk). The output is labeled R'/S'.](a33da0f14e456f92539ce3e9b7d81f9a_img.jpg) + +The diagram illustrates the internal architecture of an OEO-type reach extender. On the left, an external interface labeled S'/R' connects to a Diplexer. The Diplexer's output branches into two paths: one to an RX block and another to a TX block. Both the RX and TX blocks are connected to a central EONU block. The RX block also receives a clock signal (clk) from the EONU. The TX block sends a clock signal (clk) to the EONU. The EONU is also connected to a Local controller block. On the right side of the extender, another Diplexer is connected to the EONU. This Diplexer's output branches into two paths: one to an RX block and another to a TX block. Both the RX and TX blocks are connected to the EONU. The RX block receives a clock signal (clk) from the EONU. The TX block sends a clock signal (clk) to the EONU. The final output on the right is labeled R'/S'. The entire assembly is enclosed in a dashed box, and a small label 'G.9807.2(17)\_F11' is present at the bottom right. + +Figure 11: OEO-type reach extender with EONU for management purposes. The diagram shows a dashed box containing a Diplexer, RX, TX, EONU, and a Local controller. The left side has an S'/R' interface connected to a Diplexer. The Diplexer is connected to an RX and a TX. The RX is connected to the EONU and a clock (clk). The TX is connected to the EONU and a clock (clk). The EONU is connected to the Local controller. The right side has a Diplexer connected to an RX and a TX. The RX is connected to the EONU and a clock (clk). The TX is connected to the EONU and a clock (clk). The output is labeled R'/S'. + +Figure 11 – OEO-type reach extender with EONU for management purposes + +OEO-based REs should be enhanced to support dual rate operation. In the upstream, the RX near the S'/R' reference point should be capable of receiving both 2.5G and 10G burst signals. The TX near the R'/S' reference point should be capable of transmitting both 2.5G and 10G signals. When the recoding scheme of Appendix IV is employed in the RE, the TX near the R'/S' reference point should conduct such signal recoding and transmit 10G signals in continuous mode to the OLT. + +The continuous mode OEO RE is a subtype of OEO RE. The S'/R' interface of CM OEO RE is the same as that of the OEO RE. In the CM RE, a BM-to-CM converter is used to convert the burst signal to a continuous signal. The downstream signal (denoted CMXGSPON\_D) has a bit rate of 9.953 28 Gbit/s, and a frequency accuracy of 32 ppm in the worst case (where the OLT is in free running mode). The upstream signal (denoted CMXGSPON\_U) has a bit rate of 9.953 28 Gbit/s or 2.488 32 Gbit/s (for XGS-PON and XG-PON, respectively), and a frequency accuracy of 32 ppm in the worst case (where the OLT is in free running mode). It must be noted, however, that the upstream signal is always synchronous with the downstream signal. + +The CMXGSPON\_U signal is composed of the regenerated upstream bursts and some stuffing signal inserted between the bursts. The stuffing signal is a bit pattern that is well balanced in order to avoid long CID. This continuous signal is transmitted by the R"/S" interface. The stuffing bit pattern is configured at both the transmitter and receiver. The means that such a configuration is for further study. The pattern is somewhat arbitrary; however, it does need to satisfy a few basic requirements to avoid impacting the physical layer: it should have approximately a 1:1 mark to space ratio, and it should have approximately a 50% transition density. The OEO RE regenerates the received data from ONUs, and therefore does not unscramble the data from the ONUs. + +The upstream frame is depicted in Figure 12. It is important to note that the incoming upstream bursts each have a unique and independent bit clock phase. At its output, the BM-to-CM converter produces + +a signal that has a single continuous bit clock phase. Therefore, the BM-to-CM converter must buffer each incoming burst of data and re-time it with its output clock. + +![Diagram of the frame structure for the upstream CMXGSPON_U signal. It shows two input bursts, ONT A and ONT B, being multiplexed into a single continuous stream. ONT A's data is followed by a stuffing pattern, and then ONT B's data (preamble and data) is added. A buffering delay is indicated for ONT A. Red text annotations explain that there may be 0 to 7 zeros between the end of ONT A data and the start of the stuffing pattern, and that 0 to 7 bits of the preamble from ONT B may be overwritten by the stuffing pattern. The diagram is labeled G.9807.2(17)_F12.](bd0b93e7a46ede276d0a3b79ac487bd9_img.jpg) + +There may be between 0 and 7 zeros between the end of data from ONU A and the start of the stuffing pattern + +Between 0 and 7 bits of the preamble from ONU B may be overwritten by the stuffing pattern + +G.9807.2(17)\_F12 + +Diagram of the frame structure for the upstream CMXGSPON\_U signal. It shows two input bursts, ONT A and ONT B, being multiplexed into a single continuous stream. ONT A's data is followed by a stuffing pattern, and then ONT B's data (preamble and data) is added. A buffering delay is indicated for ONT A. Red text annotations explain that there may be 0 to 7 zeros between the end of ONT A data and the start of the stuffing pattern, and that 0 to 7 bits of the preamble from ONT B may be overwritten by the stuffing pattern. The diagram is labeled G.9807.2(17)\_F12. + +**Figure 12 – Frame of the upstream CMXGSPON\_U signal** + +Specific techniques for implementing BM-to-CM are beyond the scope of this Recommendation; however, there are a couple of basic methods for detecting the gaps between bursts. The following paragraphs provide some informative discussion of these methods. + +Detecting the gap at the optical layer (fibre to PHY interface). On the OEO RE, the optical power is detected, and a control signal that can be used to control the insertion is generated accordingly. + +Detecting the gap at the logical layer (PHY to TC interface). There are some regular patterns (typically the all zeroes pattern) in the burst gaps that can be detected and used to generate the control signal. Upon the completion of data synchronization, the receiver accepts the burst data while at the same time it is searching for the end of the burst. When it detects the burst termination by finding the expected pattern, it can reset the burst receiver. Detecting the beginning of bursts requires 32 bit pattern @2.48832 Gbit/s matching, except for cases where the receiver produces random data between bursts, in which case 96 bit patterns are required for a reliable result. Also, 96 bit pattern @2.48832 Gbit/s matching is required to detect the end of bursts for a reliable result (as the user's payload data is substantially random). These numbers of digits required are based on statistical calculations of the probability of missing a burst event or creating a false burst event. Shorter or longer pattern matching is possible, with the concomitant change in error probability. + +The gap detector will require a logical buffer to store the upstream data to compensate for the nonzero response time of the gap detector, so as to avoid long gaps of all-zero data. However, the stuffing pattern is typically byte oriented, while the aligned bursts can be at any arbitrary bit timing. Therefore, in this case an integral number of 0 to 7 bits of zeroes should be expected at the end of each burst, and the last byte of the stuffing pattern will overwrite an integral number of 0 to 7 bits of the following burst's preamble. + +The CM-to-BM converter can find the boundaries of the bursts using the logical layer detection method. Importantly, the pattern between the bursts is known to be filled with the stuffing pattern, and so the detection algorithm can be quite simple and should require only 32 bits of pattern matching to detect the start of burst, and 96 bits to detect the end of burst. The comment previously made on lengths of bit pattern matching applies here as well. + +As with the ordinary OEO RE, the RE system clock is driven by the downstream signal, and the upstream signal from the ONUs is locked synchronously to the downstream signal that the RE sends to them. The frequency, jitter, and jitter tolerances of the OLT and ONU equipment are given in Annex B of [ITU-T G.9807.1]. + +The converted CM signal can optionally be transported over an OTN path. See Appendix IV for more information. + +## **6.3 Hybrid architectures** + +A hybrid architecture using an optical amplifier for the downstream requires a clock reference for the upstream burst-mode receiver and transmitter. This has to be provided by an EONU used for management (refer to clause 7.2). Possible hybrid extender architectures are shown in Figure 13. + +![Block diagram of a hybrid reach extender architecture (a).](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +a) + +This diagram shows a hybrid reach extender architecture. On the left, an external port labeled S'/R' connects to a Diplexer. The Diplexer's output is connected to a Downstream amplifier and an RX block. The RX block receives 'Burst control' and 'Clock' signals and sends data to a TX block. The TX block's output is connected to another Diplexer on the right. This second Diplexer's output is connected to a Tap and an EONU block. The Tap outputs the signal R'/S'. The EONU block receives 'Burst' and 'Clock control' signals from a Local controller and is connected to the Downstream amplifier. The Local controller is also connected to the Downstream amplifier. + +Block diagram of a hybrid reach extender architecture (a). + +The RE upstream RX and TX should be enhanced as the same way in Clause 6.2 (OEO-based RE) to support upstream dual rate in XG(S)-PON. + +![Block diagram of a hybrid reach extender architecture (b).](2cde062fd82833415971a8bd1a2cafab_img.jpg) + +b) + +This diagram shows another hybrid reach extender architecture. An external port labeled S'/R' connects to a Diplexer. The Diplexer's output is connected to a TX block (receiving 'clk') and an Upstream amplifier. The Upstream amplifier's output is connected to a Tap, which outputs the signal R'/S'. The Tap is also connected to a TX block and a Diplexer. The TX block sends data to an EONU block, which is controlled by a Local controller. The EONU block is also connected to an RX block (receiving 'clk'). The RX block's output is connected to the second Diplexer, which also receives signals from the Tap. The Local controller is connected to the RX block and the EONU block. + +Block diagram of a hybrid reach extender architecture (b). + +![Block diagram of a hybrid reach extender architecture (c).](8307f6b04df072c9332f9987e034272c_img.jpg) + +c) + +This diagram shows a third hybrid reach extender architecture. An external port labeled S'/R' connects to a Diplexer. The Diplexer's output is connected to two cascaded amplifiers (triangles). The output of the second amplifier is connected to a RX block (receiving 'Burst' and 'Clock control') and a TX block (receiving 'Clock'). The RX block sends data to the TX block. The TX block's output is connected to a Diplexer on the right. This Diplexer's output is connected to a Tap, which outputs the signal R'/S'. The Tap is also connected to an EONU block, which is controlled by a Local controller. The EONU block is also connected to the cascaded amplifiers. The Local controller is also connected to the cascaded amplifiers. + +Block diagram of a hybrid reach extender architecture (c). + +The RE upstream RX and TX should be enhanced as the same way in Clause 6.2 (OEO-based RE) to support upstream dual rate in XG(S)-PON. + +![Block diagram of a hybrid reach extender architecture (d).](33a8f3f01dfa8bce75d23017855a13c5_img.jpg) + +d) + +This diagram shows a fourth hybrid reach extender architecture. An external port labeled S'/R' connects to a Diplexer. The Diplexer's output is connected to a TX block (receiving 'clk') and two cascaded amplifiers (triangles). The output of the second amplifier is connected to a Tap, which outputs the signal R'/S'. The Tap is also connected to a TX block and a Diplexer. The TX block sends data to an EONU block, which is controlled by a Local controller. The EONU block is also connected to an RX block (receiving 'clk'). The RX block's output is connected to the second Diplexer, which also receives signals from the Tap. The Local controller is connected to the RX block and the EONU block. + +Block diagram of a hybrid reach extender architecture (d). + +G.9807.2(17)\_F13 + +**Figure 13 – Possible architectures for hybrid reach extenders** + +## 6.4 Wavelength conversion reach extenders + +A WC-RE unit has the capability of performing the WC function in the upstream and downstream channel. The functional architecture of a WC-RE unit is presented in Figure 14. The WC function in the upstream channel converts $\lambda_U$ to $\lambda_{U\_OTL}$ and the WC function in the downstream channel, converts $\lambda_{D\_OTL}$ to $\lambda_D$ . The RE function could either be the OA or OEO type reach extension function as described in clauses 6.1 to 6.3. + +The functional blocks in Figure 14 only represent logical functions, rather than a specific physical implementation. The functional blocks in Figure 14 can be implemented in a variety of ways; as a separate physical element, component, or subassembly performing the desired functions, including implementations whereby WC function may be implemented as an integral part of the existing elements of the RE unit, as discussed in Appendix V. + +There are several optional elements in this architecture. + +- In some implementations, the local controller (LC), used optionally in remotely managed RE units, may additionally need to control the WC function implementation, selecting the target transmission wavelength (in the case of WC-enabled OEO-type REs) or controlling the operating point for all optical wavelength converters (in the case of both OA-type and OEO-type REs equipped with WC function). The LC is served by an E-ONU, which in Figure 14 is connected to one of the outputs of the WC-RE. Other methods of connecting the E-ONU to the PON signal paths are possible, as well as providing protection for the management channel. +- One or two fibres can be employed for the OTL. +- In certain implementations of the RE unit, it may be also necessary to guarantee that the clock signal is exchanged between the upstream and downstream channels for proper bit alignment and phase detection. + +![Figure 14: Internal structure of a WC-RE unit with optional WC function shown for both upstream and downstream channels.](9cd90f495b95ad2116ff780248c26d95_img.jpg) + +The diagram illustrates the internal architecture of a Wavelength Conversion Reach Extender (WC-RE) unit. On the left, multiple WC-RE units are shown, labeled WC-RE1 and WC-REn. Each unit contains a Diplexer, an REupstream block, a WC (Wavelength Converter) block, and an REdownstream block. In the first unit (WC-RE1), the Diplexer splits the incoming signal into the REupstream block, which converts $\lambda_U$ to $\lambda_{U\_OTL}$ , and the REdownstream block, which converts $\lambda_{D\_OTL}$ to $\lambda_D$ . The second unit (WC-REn) includes a Tap and an E-ONU connected to a Local controller. The WDM multiplexer/demultiplexer combines the signals from all units and outputs them as $\lambda_{D\_OTL}$ and $\lambda_{U\_OTL}$ . The diagram is labeled with S'/R' on the left and R''/S'' on the right. A reference code G.9807.2(17)\_F14 is in the bottom right corner. + +Figure 14: Internal structure of a WC-RE unit with optional WC function shown for both upstream and downstream channels. + +**Figure 14 – Internal structure of a WC-RE unit with optional WC function shown for both upstream and downstream channels** + +## 6.5 Wavelength re-conversion at OLT + +The OLT WC function block is required to ensure that the existing optical interfaces, which are compatible with Annex B of [ITU-T G.9807.1], at the OLT do not need to be redefined. + +Figure 15 presents the functional architecture of the WC-OLT unit, with optional WC function implementation for both downstream and upstream channels. An optional management function based on an E-ONU function is also presented; however, since this equipment is likely to be located in the central office other management mechanisms may be used. + +One or two fibres can be employed for the OTL. + +![Figure 15: Internal structure of a WC-OLT unit with optional WC functions shown for both upstream and downstream channels. The diagram illustrates the signal flow between S''/R'' and S/R interfaces through a WC-OLT unit. On the left, the S''/R'' interface handles wavelengths lambda_D_OTL and lambda_U_OTL. These connect to a WDM multiplexer/demultiplexer. To the right of the WDM are multiple WC-RE units (WC-RE1 to WC-REn). Each WC-RE unit contains two Diplexers and two Wavelength Conversion (WC) blocks. Downstream signals (lambda_D_OTL) pass through a Diplexer, a WC block (converting to lambda_D), and another Diplexer to reach the S/R interface. Upstream signals (lambda_U) follow a reverse path through Diplexers and a WC block (converting to lambda_U_OTL). A Local controller and an EONU (connected via a Tap to the S/R side) provide management and control functions. The diagram is labeled G.9807.2(17)_F15.](10781f43062bf3e9601a1e086710556c_img.jpg) + +Figure 15: Internal structure of a WC-OLT unit with optional WC functions shown for both upstream and downstream channels. The diagram illustrates the signal flow between S''/R'' and S/R interfaces through a WC-OLT unit. On the left, the S''/R'' interface handles wavelengths lambda\_D\_OTL and lambda\_U\_OTL. These connect to a WDM multiplexer/demultiplexer. To the right of the WDM are multiple WC-RE units (WC-RE1 to WC-REn). Each WC-RE unit contains two Diplexers and two Wavelength Conversion (WC) blocks. Downstream signals (lambda\_D\_OTL) pass through a Diplexer, a WC block (converting to lambda\_D), and another Diplexer to reach the S/R interface. Upstream signals (lambda\_U) follow a reverse path through Diplexers and a WC block (converting to lambda\_U\_OTL). A Local controller and an EONU (connected via a Tap to the S/R side) provide management and control functions. The diagram is labeled G.9807.2(17)\_F15. + +**Figure 15 – Internal structure of a WC-OLT unit with optional WC functions shown for both upstream and downstream channels** + +The functional blocks in Figure 15 only represent logical functions, rather than a specific physical implementation. The functional blocks in Figure 15 can be implemented in a variety of ways as a separate physical element, component or subassembly performing the desired functions, including implementations, whereby WC function may be implemented as an integral part of the existing elements of an OLT unit, as discussed in Appendix V. + +The WC function performs conversion of the frequency of the optical signal carried over OTL in downstream and upstream directions, adjusting it to the conditions required at the S/R and S''/R'' interfaces. The WC function in an RE unit may also be implemented in a wavelength transparent way in downstream or upstream directions, depending on user requirements. + +### 6.5.1 Operation of the WC function in the downstream channel + +Implementation of the WC-OLT function in the downstream channel is optional and depends on the implementation of the WC function in the RE unit. + +If the WC-OLT function is implemented, the optical signal received from the OLT at $\lambda_D$ is converted into $\lambda_{D\_OTL}$ , which is then transmitted towards the WC-enabled RE over the OTL. In practice, that means that the optical signal received at $\lambda_D$ , compliant with ITU-T G.9807-series Recommendations, can be converted into any wavelength $\lambda_{D\_OTL}$ . + +Detailed information about the wavelength transparent WC function is provided in clause 8.6. + +$\lambda_{D\_OTL}$ is defined in clause 8.6. + +### 6.5.2 Operation of the WC function in the upstream channel + +Implementation of the WC-OLT function in the upstream channel is optional and depends on the implementation of the WC function in the RE unit. + +The optical signal received from the OTL at $\lambda_{U\_OTL}$ is converted into $\lambda_U$ compliant with ITU-T G.9807-series Recommendations and then delivered to the OLT connected to the S/R interface of the WC function. This way, the WC function adapts the optical signal received from the ONU over the OTL into the existing OLT receiver that is compliant with Annex B of [ITU-T G.9807.1]. + +Detailed information about the wavelength transparent WC function is provided in clause 8.6. + +$\lambda_{U\_OTL}$ is defined in clause 8.6. + +## 6.6 Combination G-PON and XG(S)-PON reach extenders + +The essential arrangement of a combo RE (plus the optional video overlay extender) is shown in Figure 16. This shows that all the externally observable characteristics of the G-PON extender and XG(S)-PON extender are supported, and are *functionally* separate. The simplest way to arrive at such a function is to implement the two REs separately, and to multiplex them using passive WDM filters specified in [ITU-T G.984.5]. Furthermore, this split enables either G-PON (ITU-T G.984 series) systems or XG(S)-PON systems [ITU-T G.9807.1] to be extended. However, as mentioned later, there are several levels of integration that can have benefits in higher optical performance or lower parts count and cost. + +![Figure 16: Functional schematic of a combo reach extender. The diagram shows two identical functional blocks for G-PON and XG(S)-PON reach extenders. Each block consists of a WDM1r filter connected to an S/R' interface on the left and an R'/S' interface on the right. The WDM1r filter is connected to three parallel paths: 1) G-PON RE (1490 nm / 1310 nm), 2) XG(S)-PON RE (1577 nm / 1270 nm), and 3) Video amplifier (1555 nm). The G-PON RE and XG(S)-PON RE are connected to the WDM1r filter on the right side. The Video amplifier is connected to the WDM1r filter on the right side via a dashed line. The diagram is labeled G.9807.2(17)_F16.](a51105b2031bad93b818b82f071c6add_img.jpg) + +The diagram illustrates the functional schematic of a combo reach extender. It features two main WDM1r filter blocks. The left WDM1r filter is connected to an S/R' interface and has three output paths: 1490 nm / 1310 nm to a G-PON RE, 1577 nm / 1270 nm to an XG(S)-PON RE, and 1555 nm to a Video amplifier (indicated by a dashed line). The right WDM1r filter is connected to an R'/S' interface and receives three input paths: 1490 nm / 1310 nm from the G-PON RE, 1577 nm / 1270 nm from the XG(S)-PON RE, and 1555 nm from the Video amplifier. The G-PON RE and XG(S)-PON RE are represented by solid boxes, while the Video amplifier is represented by a dashed box. The diagram is labeled G.9807.2(17)\_F16. + +Figure 16: Functional schematic of a combo reach extender. The diagram shows two identical functional blocks for G-PON and XG(S)-PON reach extenders. Each block consists of a WDM1r filter connected to an S/R' interface on the left and an R'/S' interface on the right. The WDM1r filter is connected to three parallel paths: 1) G-PON RE (1490 nm / 1310 nm), 2) XG(S)-PON RE (1577 nm / 1270 nm), and 3) Video amplifier (1555 nm). The G-PON RE and XG(S)-PON RE are connected to the WDM1r filter on the right side. The Video amplifier is connected to the WDM1r filter on the right side via a dashed line. The diagram is labeled G.9807.2(17)\_F16. + +Figure 16 – Functional schematic of a combo reach extender + +Figures 17 to 19 illustrate some possible implementations of combo REs that achieve some level of integration between the two RE functions. The first is that the WDM1 filters can be merged with the diplexing filters in the RE units themselves, as shown in Figure 17. This essentially utilizes not only the dual-fibre interface of the WDM1 as described in [ITU-T G.984.5], but also a dual-fibre interface for the G-PON as well. + +![Figure 17: Merging of the diplexer and WDM1 filter functions. The diagram shows two identical configurations. The top configuration uses separate WDM1r filters for each RE type: G-PON downstream RE (1490 nm), G-PON upstream RE (1310 nm), XG-PON downstream RE (1577 nm), and XG-PON upstream RE (1270 nm). The bottom configuration merges these into a single WDM1r filter for G-PON and another for XG(S)-PON. Both configurations show S'/R' and R'/S' interfaces on the left and right sides. The label G.9807.2(17)_F17 is at the bottom right.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +Figure 17: Merging of the diplexer and WDM1 filter functions. The diagram shows two identical configurations. The top configuration uses separate WDM1r filters for each RE type: G-PON downstream RE (1490 nm), G-PON upstream RE (1310 nm), XG-PON downstream RE (1577 nm), and XG-PON upstream RE (1270 nm). The bottom configuration merges these into a single WDM1r filter for G-PON and another for XG(S)-PON. Both configurations show S'/R' and R'/S' interfaces on the left and right sides. The label G.9807.2(17)\_F17 is at the bottom right. + +**Figure 17 – Merging of the diplexer and WDM1 filter functions** + +The second is the merging of the downstream or upstream amplifier functions for both G-PON and XG(S)-PON, as shown in Figure 18. This is most possible with the upstream amplifiers, as the wavebands for the two systems are reasonably close together, and semiconductor optical amplifier (SOA) devices can be made with sufficient bandwidth. However, it is theoretically possible to do this with the downstream only, or with both directions (as shown). Note that in this case, the WDM filters and diplexers would likely be replaced or augmented with optical circulator devices. + +![Figure 18: Merging of the downstream and upstream amplifiers functions in a combo reach extender. The diagram shows a loop with two optical circulators on the left and right. The top path contains an Upstream OA RE handling 1270 nm and 1310 nm wavelengths. The bottom path contains a Downstream OA RE handling 1577 nm and 1490 nm wavelengths. S'/R' and R'/S' interfaces are shown on the left and right. The label G.9807.2(17)_F18 is at the bottom right.](79e1709a7317ead45379cbb8ff3ba802_img.jpg) + +Figure 18: Merging of the downstream and upstream amplifiers functions in a combo reach extender. The diagram shows a loop with two optical circulators on the left and right. The top path contains an Upstream OA RE handling 1270 nm and 1310 nm wavelengths. The bottom path contains a Downstream OA RE handling 1577 nm and 1490 nm wavelengths. S'/R' and R'/S' interfaces are shown on the left and right. The label G.9807.2(17)\_F18 is at the bottom right. + +**Figure 18 – Merging of the downstream and upstream amplifiers functions in a combo reach extender** + +The third aspect that can be merged is the common equipment functions of the RE equipment, including the controllers and power conversion or distribution functions. This is most likely in implementations that support multiple RE interfaces in a single unit, as shown in Figure 19. In this case, there is the possibility that the G-PON system and the XGS-PON system could be interconnected so that each could act as a back-up interface for the other. Alternatively, if the two systems are to be segregated, this can also be done, at the cost of additional protection interfaces for either system. + +![Figure 19: Merging of the common equipment functions in a combo reach extender. The diagram shows two configurations. The top configuration uses separate G-PON and XG-PON REs, while the bottom configuration uses combined G-PON and XG(S)-PON REs. Both configurations include WDM1r units, an Equipment controller, and an Equipment power source. Wavelengths 1490 nm, 1310 nm, 1577 nm, and 1270 nm are indicated for the various components.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +The diagram illustrates two configurations for merging common equipment functions in a combo reach extender. Both configurations consist of three parallel branches, each containing a WDM1r unit, a Remote Equipment (RE) unit, and another WDM1r unit. The left WDM1r units have S/R' interfaces, and the right WDM1r units have R'/S' interfaces. The RE units are connected to an Equipment controller and an Equipment power source. + +**Top Configuration:** This configuration uses separate G-PON and XG-PON REs. Each branch contains a G-PON RE and an XG-PON RE. The WDM1r units are connected to these REs at wavelengths 1490 nm, 1310 nm, 1577 nm, and 1270 nm. The Equipment controller and Equipment power source are connected to the XG-PON E-ONU and XG-PON RE units. + +**Bottom Configuration:** This configuration uses combined G-PON and XG(S)-PON REs. Each branch contains a G-PON RE and an XG(S)-PON RE. The WDM1r units are connected to these REs at wavelengths 1490 nm, 1310 nm, 1577 nm, and 1270 nm. The Equipment controller and Equipment power source are connected to the XG(S)-PON E-ONU and XG(S)-PON RE units. + +Wavelengths indicated: 1490 nm, 1310 nm, 1577 nm, 1270 nm. + +G.9807.2(17)\_F19 + +Figure 19: Merging of the common equipment functions in a combo reach extender. The diagram shows two configurations. The top configuration uses separate G-PON and XG-PON REs, while the bottom configuration uses combined G-PON and XG(S)-PON REs. Both configurations include WDM1r units, an Equipment controller, and an Equipment power source. Wavelengths 1490 nm, 1310 nm, 1577 nm, and 1270 nm are indicated for the various components. + +**Figure 19 – Merging of the common equipment functions in a combo reach extender** + +## 6.7 Increased fanout reach extenders + +As explained previously, it is in some ways desirable to increase the fanout of the RE function to improve sharing of the upstream devices. This section outlines two possible methods for achieving this. The first possibility is to employ an optical method, as shown in Figure 20. In the downstream direction, the RE function is implemented with a more powerful transmitter, and this would drive an optical splitter that feeds multiple S'/R' interfaces. In the example shown, this is an OEO-type, but an OA-type RE function is also possible. In the upstream direction, the multiple S'/R' ports are connected to a mode-coupling receiver (MCR) [b-Cheng]. The MCR allows the combination of the multiple single-mode inputs on to a single multimode receiver without intrinsic optical loss. In this way, the sensitivity of the RE S'/R' interface can be maintained. + +The second possibility is to employ electrical splitting, as shown in Figure 21. In this case, several S'/R' interfaces are terminated using OLT-like transceivers, and the resulting electrical interfaces are connected to a single ONU-like transceiver. In the downstream, the signal is broadcast, and in the upstream, the signals are electrically combined (added). The downstream-derived clock is also distributed to all the functional blocks. Because the additional splitting and combining occur in the electrical domain after amplification has already taken place, the sensitivity of the S'/R' interfaces can be maintained. + +![Figure 20: RE fanout increased using mode-coupling receiver technology. The diagram shows two S'/R' interfaces connected to Diplexers. The top Diplexer's output is connected to a Mode coupling Rx block. The bottom Diplexer's output is connected to an amplifier, which then connects to a Tx block. Both the Mode coupling Rx and the Tx block are connected to a central Tx block. The central Tx block is connected to a Diplexer, which outputs to an R'/S' interface. A Clock signal is also shown connected to the central Tx block. The diagram is labeled G.9807.2(17)_F20.](365b54f616aff249b4e6c0edafdcb9b3_img.jpg) + +Figure 20: RE fanout increased using mode-coupling receiver technology. The diagram shows two S'/R' interfaces connected to Diplexers. The top Diplexer's output is connected to a Mode coupling Rx block. The bottom Diplexer's output is connected to an amplifier, which then connects to a Tx block. Both the Mode coupling Rx and the Tx block are connected to a central Tx block. The central Tx block is connected to a Diplexer, which outputs to an R'/S' interface. A Clock signal is also shown connected to the central Tx block. The diagram is labeled G.9807.2(17)\_F20. + +**Figure 20 – RE fanout increased using mode-coupling receiver technology** + +![Figure 21: RE fanout increased using electrical splitting technology. The diagram shows two S'/R' interfaces connected to Diplexers. Each Diplexer is connected to an Rx block and a Tx block. The Rx blocks are connected to a central summation node (indicated by a circle with a plus sign). The Tx blocks are also connected to this central summation node. The output of the summation node is connected to a Tx block, which is then connected to a Diplexer, which outputs to an R'/S' interface. A Clock signal is also shown connected to the Tx block. The diagram is labeled G.9807.2(17)_F21.](eb03559a4d92ea9ebd63ea9be663c50a_img.jpg) + +Figure 21: RE fanout increased using electrical splitting technology. The diagram shows two S'/R' interfaces connected to Diplexers. Each Diplexer is connected to an Rx block and a Tx block. The Rx blocks are connected to a central summation node (indicated by a circle with a plus sign). The Tx blocks are also connected to this central summation node. The output of the summation node is connected to a Tx block, which is then connected to a Diplexer, which outputs to an R'/S' interface. A Clock signal is also shown connected to the Tx block. The diagram is labeled G.9807.2(17)\_F21. + +**Figure 21 – RE fanout increased using electrical splitting technology** + +# 7 General requirements for XG(S)-PON reach extenders + +## 7.1 Compatibility + +The RE must be compatible with existing XGS-PON 9.953 28/9.953 28 Gbit/s ONU or XG-PON 9.953 28/2.388 32 Gbit/s ONU equipment and class N1 or N2 ODN. It is possible for the extender to support a more capable ODN, such as the class E1 or E2 defined in [ITU-T G.987.2]. + +The RE (and, if applicable, its associated wavelength converter or CM-to-BM converter located at the OLT) should be compatible with the existing OLT equipment to the maximum extent possible. There are physical factors that might make it difficult to support complete backward compatibility with the OLT, so some modification of the OLT may be necessary. However, it is envisaged that these modifications will be limited to parameter adjustments of the PMD and TC layers, and will not require wholesale hardware replacements. + +## 7.2 Management + +The RE must support full management of its configuration, performance monitoring and fault reporting. The scope of parameters under management depends on the extender type, and it may be that some of the OLT interface management features may not be supported in the extender. + +The management of the extender should be provided using the OLT as a proxy. That is, the extender is considered to be an extension of the OLT network element, and no additional interface to the operator's management network will be provided. + +For the mid-span extender, the simplest way to accommodate these requirements is to furnish the extender equipment with the functions of an EONU to the extent that a PLOAM and an ONU management and control interface (OMCI) channel can be established between the extender and the OLT. The attributes that are specific to extenders are described in [ITU-T G.988]. + +### 7.2.1 Provisioning and operation of reach extenders managed through EONU + +The OLT CT will automatically discover the presence of EONU managed RE and take all necessary measures depending on the device performance, to enable a simple and hitless operation experience. + +In the serial number field, the four most significant bits (MSBs) are the American Standard Code for Information Interchange- (ASCII-) coded alphanumeric label of the vendor, which only uses code points from 65 to 90, both in [ITU-T G.987.3] and [ITU-T G.9807.1]. This means that the leading bit of each byte is left unused so far. + +Therefore in order to enable unambiguous identification of an EONU, the vendor identifier (ID) of the EONU should be the ordinary vendor ID plus 0x80 00 00 00. + +### 7.2.2 Means to discover the ONU to RE-CT mapping + +Several solutions to discover the ONU to RE-CT mapping have been identified. In order to cause no breach to interoperability, only one will be retained. + +To cause as little disruption as possible, solutions rely on the basic principle of the OLT issuing a simultaneous specific bandwidth map to the ONU in parallel with a command for the RE to monitor what is going on, on its RE-CT detecting an upstream signal or a specific power level to be retrieved through OMCI messaging. + +The details are for further study. + +### 7.2.3 Reach extender-specific PLOAM messages + +In the presence of REs, for field operations, in addition to the OC structure containing information valid on the OTL section of the PON, updates are needed to be able to retrieve accurate transmit optical level (TOL) information, corresponding to each ODN on each RE port. + +Once this ONU mapping has been found according to the method defined in clause 7.2.2, since REs do not have the ability to change the frame-contained information, it must be periodically sent by the OLT through a clear broadcast PLOAM message for easy retrieval by an analyser used by field engineers, in order to pick up the TOL value corresponding to the actual path under test among those of the full list of RE-CTs. + +Therefore the following PLOAM messages have been defined: + +PLOAM message corresponding to message type ID 0xF0 in Table C.11.2 of [ITU-T G.9807.1]: + +| Octet | Content | Description | +|-------|-----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | 0x03FF, Exclusively Broadcast. | +| 3 | Message type ID | 0xF0, "ONU to RE Mapping". | +| 4 | SeqNo | Broadcast PLOAM sequence number | +| 5 | RE/ RE CT-Id | 0xXYZTn where:
Since only four ONUs can be mapped per message, XYZ indicate the rank of the message in the announcement needed for RE-Id n depending on the number of ONUs attached to the RE.
T set to "1" indicates the last message for RE Id number n
"n" is a 4 bit RE-Id as given in the wavelength channel (WLCH) of the OC structure. | +| 6 | Number of ONU for RE-Id "n" | 0 – 254 Number of ONUs attached to the given CT
255 – reserved for the case of all ONU attached to a single RE | +| 7-10 | First ONU Vendor_ID | See clause C.11.2.6.1 of [ITU-T G.9807.1] | +| 11-14 | First ONU VSSN | See clause C.11.2.6.2 of [ITU-T G.9807.1] | +| 15-18 | Second ONU Vendor_ID | See clause C.11.2.6.1 of [ITU-T G.9807.1] | +| 19-22 | Second ONU VSSN | See clause C.11.2.6.2 of [ITU-T G.9807.1] | +| ... | | | +| 31-34 | Fifth ONU Vendor_ID | See clause C.11.2.6.1 of [ITU-T G.9807.1] | +| 35-38 | Fifth ONU VSSN | See clause C.11.2.6.2 of [ITU-T G.9807.1] | +| 39-40 | Padding | | +| 41-48 | MIC | Message integrity check, computed using the default PLOAM integrity key. | + +A cyclic broadcast PLOAM message sent in clear transmits the full set of TOL values on the PON for activated RE-CTs. + +Combined with RE-CTs – ONU identity mapping, field engineers can retrieve the information applicable to the ODN segment they are operating on. + +Note that detection of the RE bit set in the downstream frame OC structure will tell field engineers that the frame header TOL value cannot be used when working on an ODN section. + +PLOAM message corresponding to message type ID 0xF1 of Table C.11.2 of [ITU-T G.9807.1]: + +| Octet | Content | Description | +|-------|-----------------|----------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | 0x03FF, exclusively Broadcast. | +| 3 | Message type ID | 0xF1, "TOL & RE CT-Id mapping". | +| 4 | SeqNo | Broadcast PLOAM sequence number | +| 5 | RE/ RE CT-Id | 0xN1 | +| 6-7 | TOL – RE CT1 | 0x0000 Value of TOL field for RE/ RE CT Id 1
See TOL in clause C.10.1.1.1.3 of [ITU-T G.9807.1] | + +| Octet | Content | Description | +|-------|-----------------|----------------------------------------------------------------------------------------------------| +| 8 | RE/ RE CT-Id 2 | 0xN2 | +| 9-10 | TOL – RE CT2 | 0x0000 Value of TOL field for RE/ RE CT Id 2
See TOL in clause C.10.1.1.1.3 of [ITU-T G.9807.1] | +| ... | | | +| 38 | RE/ RE CT-Id 12 | 0xN12 | +| 39-40 | | 0x0000 Value of TOL field for RE/ RE CT Id 2
See TOL in clause C.10.1.1.1.3 of [ITU-T G.9807.1] | +| 41-48 | MIC | Message integrity check, computed using the default PLOAM integrity key. | + +There can be one EONU per RE or alternatively one shared EONU can provide a management interface to multiple REs in a shelf (extender chassis). + +The EONU should provide a dying gasp function. + +## 7.3 Power + +The exact requirements of RE powering lie outside the scope of this Recommendation. However, some generic comments on this issue are given here. The mid-span extender requires electrical power. This may be a practical difficulty when the extender is located in the field. Also, the power supply is usually designed to be resilient against transient failures of the primary power source. To reduce the size of the power backup equipment, the power consumption should be reduced as much as possible. + +## 7.4 Optional enhancements + +The following issues are of interest for RE technology, but are considered to lie outside the scope of this Recommendation. + +Resilience in the presence of a RE may be required due to the extended reach. There are several functions that could be protected (e.g., OTL, RE optics, OLT optics). The type B protection scheme is considered in Appendix II. + +# 8 Specifications for mid-span extenders + +## 8.1 Optical trunk line + +The optical parameters of the optical trunk line are given in Table 1. + +**Table 1 – Physical medium dependant layer parameters of OTL** + +| Items | Unit | Specification | | | | +|----------------------------------------------------------------------------------------------------------|------|---------------|----------|-----------|----------| +| Fibre type | – | [ITU-T G.652] | | | | +| ODN class | | N1 | N2 | E1 | E2 | +| Attenuation range for the 1 260 nm to 1 280 nm range applicable for OEO type of extenders (Note 1) | dB | 14-28.5 | 16-30.5 | 18-32.5 | 20-34.5 | +| Maximum attenuation for the 1 260 nm to 1 280 nm range applicable for OA type of extenders (Note 2) | dB | 29 | 31 | 33 | 35 | +| Minimum attenuation for the 1 260 nm to 1 280 nm range applicable for OA type of extenders | dB | (Note 3) | (Note 3) | (Note 3) | (Note 3) | +| Attenuation range for the 1 575 nm to 1 581 nm range applicable for OEO type of reach extenders (Note 1) | dB | 11-23 | 13-25 | 14.5-26.5 | 16-28 | + +**Table 1 – Physical medium dependant layer parameters of OTL** + +| Items | Unit | Specification | | | | +|-----------------------------------------------------------------------------------------------------------|------|---------------------------------------|----------|----------|----------| +| Maximum attenuation for the 1 575 nm to 1 581 nm range applicable for OA type of reach extenders (Note 2) | dB | 23 | 25 | 26.5 | 28 | +| Minimum attenuation for the 1 575 nm to 1 581 nm range applicable for OA type of reach extenders | dB | (Note 3) | (Note 3) | (Note 3) | (Note 3) | +| Attenuation range for C-band applicable for WC type of extenders (Note 1) | dB | 14-28.5 | 16-30.5 | 18-32.5 | 20-34.5 | +| Maximum attenuation for L-band applicable for WC type of extenders (Note 1) | dB | 14-28.5 | 16-30.5 | 18-32.5 | 20-34.5 | +| Maximum optical path penalty | dB | 1 | | | | +| Maximum fibre distance between S/R and R'/S' points | km | 60 minus the distance used in the ODN | | | | +| Bidirectional transmission | – | 1-fibre WDM | | | | +| Maintenance wavelength | nm | See [ITU-T L.313] | | | | + +NOTE 1 – For lower attenuation values, external optical attenuators can be used. +NOTE 2 – May be varied depending on implementation. +NOTE 3 – OA implementation-dependent; for low attenuation values, an appropriately designed OA type extender or external optical attenuators can be used. + +## 8.2 Optical trunk line interface (R'/S') and OLT interface (S/R) + +The optical parameters of the R'/S' and S/R interfaces are given in Tables 2 and 3. The specifications for the OLT S/R interface are based upon the specifications of the S/R interface in Tables B.9-3 and B.9-4 of [ITU-T G.9807.1], with the noted exceptions. The specifications for the RE R'/S' interface are based upon the specifications of the R/S interface in Tables B.9-3 and B.9-4 of [ITU-T G.9807.1], with the noted exceptions. + +**Table 2 – Optical interface parameters of 9 953 Mbit/s downstream direction (OLT>Ext)** + +| Items | Unit | OEO type | OA type | +|-----------------------------------------------------------------------------------------|------|-------------------------------------|-------------------------------------| +| OLT transmitter | | | | +| All transmitter specifications in Table B.9-3 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | Same as Annex B of [ITU-T G.9807.1] | +| Extender receiver | | | | +| All receiver specifications in Table B.9-3 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | Same as Annex B of [ITU-T G.9807.1] | +| Maximum reflectance of equipment, measured at receiver wavelength | dB | Same as Annex B of [ITU-T G.9807.1] | NA | +| Bit error ratio | – | Less than $10^{-5}$ | NA | + +**Table 2 – Optical interface parameters of 9 953 Mbit/s +downstream direction (OLT>Ext)** + +| Items | Unit | OEO type | OA type | +|------------------------------------|------|-------------------------------------------------------------------------|-------------------------------------------------------------------------------------| +| Minimum sensitivity (back-to-back) | dBm | N1: -22
N2a: -22
N2b -15.5
E1: -21.5
E2a: -21
E2b: -14.5 | N1: -22
N2a: -22
N2b -15.5
E1: -21.5
E2a: -21
E2b: -14.5
(Note 1) | +| Minimum overload | dBm | N1: -5
N2a: -5
N2b -0.5
E1: -4.5
E2a: -4
E2b: +0.5 | N1: -5
N2a: -5
N2b -0.5
E1: -4.5
E2a: -4
E2b: +0.5
(Note 1) | + +NOTE 1 – The input power specifications into the OA-type extender at R'/S' interface is given in order to achieve a bit error ratio of $10^{-3}$ at the ONU. +NOTE 2 – For WC-type reach extenders, the operating wavelength may be changed; see clause 8.6. +NOTE 3 – For some optical wavelength converters, the non-return to zero (NRZ) data is inverted in the OTL section between the WC-RE and the WC-OLT. The configuration of data pattern inversion is for further study. +NOTE 4 – Typical seed light sources have a spectral power density of 6 dBm/nm. + +**Table 3a – Optical interface parameters of 9 953 Mbit/s +upstream direction (Ext>OLT)** + +| Items | Unit | OEO type | OA type | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------------------------|----------| +| Extender transmitter | | | | +| All transmitter specifications in Table B.9-4 of [ITU-T G.9807.1] unless specified here | Mbit/s | Same as Annex B of [ITU-T G.9807.1] | NA | +| Mean launched signal power minimum | dBm | +4 | (Note 1) | +| Mean launched signal power maximum | dBm | +9 | (Note 1) | +| Maximum ASE output power in the 1 255 nm to 1285 nm band launched toward OLT relative to signal output power. Condition: -28 dBm signal input power at S'/R'. | dB | NA | 7 | +| Maximum ASE output power in the 1 200 nm to 1255 nm and the 1 285 nm to 1 400 nm band launched toward OLT relative to signal output power. Condition: -28 dBm signal input power at S'/R'. | dB | NA | -4 | + +**Table 3a – Optical interface parameters of 9 953 Mbit/s +upstream direction (Ext>OLT)** + +| Items | Unit | OEO type | OA type | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|-------------------------------------|-------------------------------------| +| Maximum ASE output power in the 1 400 nm to 1 600 nm band launched toward OLT. Condition: –23 dBm signal input power at 1490 nm at R'/S'. | dBm | NA | 2 | +| OLT receiver | | | | +| All receiver specifications in Table B.9-4 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | Same as Annex B of [ITU-T G.9807.1] | +| Bit error ratio | – | Less than $10^{-6}$ | NA | +| Maximum penalty due to ASE-related power bias at OLT receiver | dB | NA | 0.5 | +| Immunity against incident ASE power (optical power bias tolerance) in the 1 285 nm to 1 335 nm band at 0.5 dB additional penalty: ASE power relative to modulated signal power. | dB | NA | 7
(Note 2) | +| NOTE 1 – Implementation-dependent. Values can be derived from the OA-type reach extender's gain specification and its allowed ODN attenuation range. Maximum and minimum signal output power may be determined from the following formulae:
$P_{\text{out(max)}} = +7 - \text{min ODN attenuation} + \text{maximum gain}$
$P_{\text{out(min)}} = +2 - \text{max ODN attenuation} + \text{minimum gain}$
NOTE 2 – ASE noise generated by the OA-type reach extender appears to the receiver as optical power bias (see Appendix I).
NOTE 3 – For WC-type reach extenders, the operating wavelength may be changed; see clause 8.6.
NOTE 4 – For some optical wavelength converters, the NRZ data is inverted in the OTL section between the WC-RE and the WC-OLT. The configuration of data pattern inversion is for further study. | | | | + +**Table 3b – Optical interface parameters of 2 488 Mbit/s +upstream direction (Ext>OLT)** + +| Items | Unit | OEO type | OA type | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------------|----------| +| Extender transmitter | | | | +| All transmitter specifications in Table 9-4 of [ITU-T G.987.2] unless specified here | Mbit/s | Same as [ITU-T G.987.2] | NA | +| Mean launched signal power minimum | dBm | +2 | (Note 1) | +| Mean launched signal power maximum | dBm | +7 | (Note 1) | +| Maximum ASE output power in the 1 255 nm to 1 285 nm band launched toward OLT relative to signal output power. Condition: –28 dBm signal input power at S'/R'. | dB | NA | 7 | +| Maximum ASE output power in the 1 200 nm to 1 255 nm and the 1 285 nm to 1 400 nm band launched toward OLT relative to signal output power. Condition: –28 dBm signal input power at S'/R'. | dB | NA | –4 | + +**Table 3b – Optical interface parameters of 2 488 Mbit/s +upstream direction (Ext>OLT)** + +| Items | Unit | OEO type | OA type | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|----------------------------|----------------------------| +| Maximum ASE output power in the 1 400 nm to 1 600 nm band launched toward OLT. Condition: –23 dBm signal input power at 1 490 nm at R'/S'. | dBm | NA | 2 | +| OLT receiver | | | | +| All receiver specifications in Table 9-4 of [ITU-T G.987.2] unless specified here | | Same as
[ITU-T G.987.2] | Same as
[ITU-T G.987.2] | +| Bit error ratio | – | Less than 10 –6 | NA | +| Maximum penalty due to ASE-related power bias at OLT receiver | dB | NA | 0.5 | +| Immunity against incident ASE power (optical power bias tolerance) in the 1 285 nm to 1 335 nm band at 0.5 dB additional penalty: ASE power relative to modulated signal power. | dB | NA | 7
(Note 2) | +| NOTE 1 – Implementation-dependent. Values can be derived from the OA-type reach extender's gain specification and its allowed ODN attenuation range. Maximum and minimum signal output power may be determined from the following formulae:
$P_{\text{out(max)}} = +7 - \text{min ODN attenuation} + \text{maximum gain}$ $P_{\text{out(min)}} = +2 - \text{max ODN attenuation} + \text{minimum gain}$ NOTE 2 – ASE noise generated by the OA-type reach extender appears to the receiver as optical power bias (see Appendix I).
NOTE 3 – For WC-type reach extenders, the operating wavelength may be changed; see clause 8.6.
NOTE 4 – For some optical wavelength converters, the NRZ data is inverted in the OTL section between the WC-RE and the WC-OLT. The configuration of data pattern inversion is for further study. | | | | + +## 8.3 Optical distribution network + +The optical parameters of the optical distribution network are given in Table B.9-2 of [ITU-T G.9807.1]. + +## 8.4 Extender interface to optical distribution network (S'/R') and ONU interface (R/S) + +The optical parameters of the S'/R' and R/S interfaces are given in Tables 4, 5a and 5b. The specifications for the RE S'/R' interface are based upon those of the S/R interface in Tables B.9-3 and B.9-4 of [ITU-T G.9807.1], with the noted exceptions. The specifications for the ONU R/S interface are based upon the specifications of the R/S interface in Tables B.9-3 and B.9-4 of [ITU-T G.9807.1], with the noted exceptions. + +**Table 4 – Optical interface parameters of 9 953 Mbit/s +downstream direction (Ext>ONU)** + +| Items | Unit | OEO type | OA type | +|-----------------------------------------------------------------------------------------|------|-------------------------------------|----------| +| Extender transmitter | | | | +| All transmitter specifications in Table B.9-3 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | NA | +| Mean launched power minimum | dBm | Same as Annex B of [ITU-T G.9807.1] | (Note 1) | + +**Table 4 – Optical interface parameters of 9 953 Mbit/s +downstream direction (Ext>ONU)** + +| Items | Unit | OEO type | OA type | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|-------------------------------------|-------------------------------------| +| Mean launched power maximum | dBm | Same as Annex B of [ITU-T G.9807.1] | (Note 1) | +| Maximum ASE power in the 1 400 nm to 1 600 nm band launched toward ONUs relative to the launched output signal power. Condition: –23 dBm signal input power at R'/S'. | dB | NA | 5 | +| Maximum ASE output power in the 1 200 nm to 1 400 nm band launched toward ONUs. Condition: –28 dBm 1270 nm signal input power at S'/R' | dBm | NA | 9 | +| ONU receiver | | | | +| All receiver specifications in Table 9-3 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | Same as Annex B of [ITU-T G.9807.1] | +| Additional penalty due ASE-related power bias at ONU receiver | dB | NA | 0.5 dB | +| Immunity against incident ASE power (optical power bias tolerance) in the 1 400 nm to 1 600 nm band at 0.5 dB additional penalty: ASE power relative to signal power. | dB | NA | 5 (Note 2) | +| NOTE 1 – Implementation-dependent. Values can be derived from the OA-type reach extender's gain and the OTL loss. Maximum and minimum signal output power may be determined by:
$P_{\text{out(min)}} = \text{OLT\_Pout\_min} + \text{minimum gain} - \text{OTL loss}$
$P_{\text{out(max)}} = \text{OLT\_Pout\_max} + \text{maximum gain} - \text{OTL loss}$
As an option, the gain can be adjusted to optimize performance (ODN attenuation range).
NOTE 2 – ASE generated by the OA extender appears to the receiver as optical power bias.
See Appendix I. | | | | + +**Table 5a – Optical interface parameters of 9 953 Mbit/s +upstream direction (ONU>Ext)** + +| Items | Unit | OEO Type | OA type | +|-----------------------------------------------------------------------------------------|-------|-------------------------------------|-------------------------------------| +| ONU transmitter | | | | +| All transmitter specifications in Table B.9-4 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | Same as Annex B of [ITU-T G.9807.1] | +| Dispersion range | ps/nm | Same as Annex B of [ITU-T G.9807.1] | 0 to –420 | +| Extender receiver | | | | +| All receiver specifications in Table B.9-4 of [ITU-T G.9807.1] unless specified here | | Same as Annex B of [ITU-T G.9807.1] | Same as Annex B of [ITU-T G.9807.1] | + +**Table 5a – Optical interface parameters of 9 953 Mbit/s upstream direction (ONU>Ext)** + +| Items | Unit | OEO Type | OA type | +|-------------------------------------------------------------------|------|-------------------------------------|---------------| +| Maximum reflectance of equipment, measured at receiver wavelength | dB | Less than –20 | Less than –20 | +| Bit error ratio | – | Less than $10^{-4}$ | NA | +| Consecutive identical digit immunity | Bit | Same as Annex B of [ITU-T G.9807.1] | NA | +| Jitter tolerance | – | NA | NA | + +**Table 5b – Optical interface parameters of 2 488 Mbit/s upstream direction (ONU>Ext)** + +| Items | Unit | OEO Type | OA type | +|--------------------------------------------------------------------------------------|-------|-------------------------|-------------------------| +| ONU transmitter | | | | +| All transmitter specifications in Table 9-4 of [ITU-T G.987.2] unless specified here | | Same as [ITU-T G.987.2] | Same as [ITU-T G.987.2] | +| Dispersion range | ps/nm | Same as [ITU-T G.987.2] | 0 to –420 | +| Extender receiver | | | | +| All receiver specifications in Table 9-4 of [ITU-T G.987.2] unless specified here | | Same as [ITU-T G.987.2] | Same as [ITU-T G.987.2] | +| Maximum reflectance of equipment, measured at receiver wavelength | dB | Less than –20 | Less than –20 | +| Bit error ratio | – | Less than $10^{-4}$ | NA | +| Consecutive identical digit immunity | Bit | Same as [ITU-T G.987.2] | NA | +| Jitter tolerance | – | NA | NA | + +## 8.5 TC layer impacts + +The introduction of an OEO RE into the PON signal path will cause some degradation of the total burst mode overhead. For most OEO type systems, the extender's own burst mode receiver must accomplish level or clock recovery. For some OA type systems, there may be a short time interval from when the burst first arrives at the OA to when the gain control mechanisms have stabilized. The extender essentially "consumes" an interval of the preamble pattern for its own adjustment before it can begin to transmit high-quality preamble upstream toward the OLT. + +The OLT and ONU must compensate for this by allowing extra preamble pattern to be transmitted before each burst. The exact amount of extra preamble depends on the design of the extender, and is best determined during operation via the extender management channel. It is expected that REs would require no more preamble than an OLT receiver, and potentially less. + +The basic procedure for network commissioning is as follows: + +Step 1: The OLT broadcasts a Profile message (profile X) on the PON. + +Step 2: The OLT activates the RE (i.e., ranges and establishes the OMCI channel). + +Step 3: The OLT obtains via the OMCI the RE's preamble requirement. + +Step 4: The OLT broadcasts a different profile message (profile Y) that includes the RE's extra preamble requirement. Note that the OLT will not command the RE to use the profile Y. Consequently, the RE will use profile X (with a normal preamble) and the ONUs will use profile Y (with the extended preamble). + +Step 5: The OLT activates all the ONUs downstream of the extender now that the upstream channel has been properly aligned. + +## 8.6 WDM wavelength allocation plan for OTL + +The wavelength allocation plans for the OTL between the S"/R" and R"/S" interfaces are defined in this section. Since the various technical options have different requirements on the wavelength allocation, we arrive at several channel plans. Examples of the application of these plans are shown in Appendix V. + +### 8.6.1 Transparent OTL wavelength allocation plan + +The transparent OTL wavelength allocation plan is presented in Table 6. The basic design principle here is to use the usual 100 GHz or 50 GHz channel grid. This arrangement should facilitate forward compatibility with the maximal set of XG(S)-PON equipment. + +**Table 6 – Transparent OTL wavelength allocation plan for upstream and downstream channels** + +| | Upstream | | Downstream | | +|------------------------------------|--------------------------|---------------------------|--------------------------|---------------------------| +| | 100 GHz | 50 GHz | 100 GHz | 50 GHz | +| Minimum channel spacing | 100 GHz | 50 GHz | 100 GHz | 50 GHz | +| Minimum central frequency | 234.3 THz
1 279.52 nm | 234.3 THz
1 279.52 nm | 189.7 THz
1 580.35 nm | 189.65 THz
1 580.77 nm | +| Maximum central frequency | 237.8 THz
1 260.69 nm | 237.85 THz
1 260.43 nm | 190.3 THz
1 575.37 nm | 190.3 THz
1 575.37 nm | +| Spectral excursion | ±20 GHz | ±10 GHz | ±20 GHz | ±10 GHz | +| Total number of supported channels | 36 | 72 | 7 | 14 | + +### 8.6.2 Conventional OTL wavelength allocation plan + +The conventional OTL wavelength plan is presented in Table 7. The basic design concept here is to use conventional wavelength assignments from [ITU-T G.694.1] or [ITU-T G.694.2]. In DWDM applications using two fibres, the C-band allocations are used for both transmission directions. In DWDM applications using a single fibre, the C-band is used for the upstream, and the L-band is used for the downstream. + +**Table 7 – The conventional OTL wavelength allocation plan** + +| | CWDM option | DWDM options for upstream and two fibres downstream | | DWDM options for single fibre downstream | | +|------------------------------------|-------------|-----------------------------------------------------|---------------------------|------------------------------------------|---------------------------| +| | | 100 GHz | 50 GHz | 100 GHz | 50 GHz | +| Minimum channel spacing | 20 nm | 100 GHz | 50 GHz | 100 GHz | 50 GHz | +| Maximum central frequency | 1471 nm | 196.0 THz
1 529.55 nm | 196.05 THz
1 529.16 nm | 190.3 THz
1 575.37 nm | 190.35 THz
1 574.95 nm | +| Minimum central frequency | 1 611 nm | 192.1 THz
1 560.61 nm | 192.1 THz
1 560.61 nm | 186.4 THz
1 608.33 nm | 186.4 THz
1 608.33 nm | +| Spectral excursion | ±6.5 nm | ±20 GHz | ±10 GHz | ±20 GHz | ±10 GHz | +| Total number of supported channels | 18 | 40 | 80 | 40 | 80 | + +### 8.6.3 Optically converted OTL wavelength allocation plan + +The optically converted wavelength allocation plan is presented in Table 8. This wavelength plan is suitable for certain WC technologies that have a limitation in the change of wavelength. For this reason, the wavelength bands are placed close to (but not overlapping) the wavelength bands of XG(S)-PON. + +**Table 8 – The optically converted OLT wavelength plan** + +| | Upstream | | Downstream | | +|------------------------------------|---------------------------|---------------------------|--------------------------|---------------------------| +| | 100 GHz | 50 GHz | 100 GHz | 50 GHz | +| Minimum channel spacing | 100 GHz | 50 GHz | 100 GHz | 50 GHz | +| Minimum central frequency | 231.30 THz
1 296.12 nm | 231.25 THz
1 296.40 nm | 190.7 THz
1 572.06 nm | 190.65 THz
1 572.48 nm | +| Maximum central frequency | 233.60 THz
1 283.36 nm | 233.60 THz
1 283.36 nm | 191.3 THz
1 567.13 nm | 191.3 THz
1 567.13 nm | +| Spectral excursion | ±20 GHz | ±10 GHz | ±20 GHz | ±10 GHz | +| Total number of supported channels | 24 | 48 | 7 | 14 | + +# Appendix I + +## Implications on OLT receivers due to insertion of OA type extenders + +(This appendix does not form an integral part of this Recommendation.) + +SOAs are presently the most practical gain element for implementing OA-type of extenders. The ASE generated by the SOA appears at the R/S interface as a broadband light source, which is converted by the photodetector section of the receiver to a DC bias current and a noise term in the electrical domain. This appendix describes the implications of this optical power bias for the receiver. + +Figure I.1 illustrates the effect of the ASE-based DC bias current on the decision threshold at the upstream receiver's sensitivity limit and overload limit, respectively. A receiver will function correctly only if it can tolerate this DC bias current with a maximum 0.5 dB power penalty over its entire input range. + +![Graph (a) showing optical power at receiver vs time. The y-axis is 'Optical power at receiver' and the x-axis is 'Time'. A solid line represents the signal power, which starts at a high level and drops to a lower level. A dashed line represents the ASE power level, which is constant. The vertical distance between the signal power and the ASE power is labeled P_ASE = -22 dBm. The vertical distance between the two signal power levels is labeled (P1-P0)/2 = -28 dBm.](a8f5e96261c2ea20a0f83f121d8fcbcb_img.jpg) + +Optical power at receiver + +$P_{ASE} = -22 \text{ dBm}$ + +$(P1-P0)/2 = -28 \text{ dBm}$ + +Time + +(a) Optical power bias tolerance at the limit of OLT sensitivity (see Table 3) + +Graph (a) showing optical power at receiver vs time. The y-axis is 'Optical power at receiver' and the x-axis is 'Time'. A solid line represents the signal power, which starts at a high level and drops to a lower level. A dashed line represents the ASE power level, which is constant. The vertical distance between the signal power and the ASE power is labeled P\_ASE = -22 dBm. The vertical distance between the two signal power levels is labeled (P1-P0)/2 = -28 dBm. + +![Graph (b) showing optical power at receiver vs time. The y-axis is 'Optical power at receiver' and the x-axis is 'Time'. A solid line represents the signal power, which starts at a high level and drops to a lower level. A dashed line represents the ASE power level, which is constant. The vertical distance between the signal power and the ASE power is labeled P_ASE = -2 dBm. The vertical distance between the two signal power levels is labeled (P1-P0)/2 = -8 dBm.](ed4ead5d57191d85eee9880ec32c4628_img.jpg) + +Optical power at receiver + +$P_{ASE} = -2 \text{ dBm}$ + +$(P1-P0)/2 = -8 \text{ dBm}$ + +Time + +(b) Optical power bias tolerance at maximum OLT receive power (see Table 3) + +G.9807.2(17)\_FI.1 + +Graph (b) showing optical power at receiver vs time. The y-axis is 'Optical power at receiver' and the x-axis is 'Time'. A solid line represents the signal power, which starts at a high level and drops to a lower level. A dashed line represents the ASE power level, which is constant. The vertical distance between the signal power and the ASE power is labeled P\_ASE = -2 dBm. The vertical distance between the two signal power levels is labeled (P1-P0)/2 = -8 dBm. + +**Figure I.1 – Optical power bias tolerance at the OLT upstream receiver** + +Generally, OLT receivers that are AC coupled and those that are DC coupled but readjust their decision thresholds at the beginning of each received burst will be tolerant of DC bias. XG(S)-PON OLT receiver implementations typically fall into one of these categories. + +In both the upstream and downstream directions, a significant portion of the ASE power spectrum falls outside the nominal operating wavelength band of the OLT or ONU transmitter. The specifications given in Table 3 assume usage of an OBF to block upstream ASE directed to the OLT + +outside the operating band of the ONU transmitter. As an option, an OBF may also be used to block ASE directed towards ONU outside the operating band of the OLT transmitter. + +OBFs improve performance by reducing ASE-ASE beat noise at the receiver and by relaxing the optical power bias tolerance requirements at the receivers. + +Note that the excess backward ASE in upstream direction produced by the downstream OA need not be filtered out. The OBF should not interfere with video wavelengths, NGA wavelengths or supervisory wavelengths, since both OEO and OA extenders would likely use WDM technology to accommodate other wavelengths. In the following example, a video overlay signal at 1 550 nm operates in a region where an OA extender may produce a significant amount of ASE. As shown in Figure I.2, WDM1 would block 1 550 nm backward ASE from reaching the video OLT, and WDM2 would keep forward ASE at 1 550 nm away from the video receiver. + +![Diagram of forward and backward ASE filtering due to WDM overlay.](2837ffdadcdb1e5bababa56b564e56ed_img.jpg) + +The diagram illustrates an optical network configuration. On the left, an oval labeled 'ODN' is connected to a rectangular block labeled 'WDM2'. To the right of 'WDM2' is a vertical line representing a bidirectional interface, with 'S/R'' on the left and 'R/S'' on the right. This interface connects to a central rectangular block labeled 'OEO/OA'. To the right of 'OEO/OA' is another vertical line representing a bidirectional interface, with 'R/S'' on the left and 'S/R'' on the right. This interface connects to a rectangular block labeled 'WDM1'. To the right of 'WDM1' is an oval labeled 'OLT'. Above the 'OEO/OA' block is a triangle representing a '1550 nm optical amplifier', which is connected to the optical paths between 'WDM2' and 'WDM1'. A small label 'G.9807.2(17)\_FI.2' is located at the bottom right of the diagram. + +Diagram of forward and backward ASE filtering due to WDM overlay. + +**Figure I.2 – Forward and backward ASE filtering due to WDM overlay** + +# Appendix II + +## Protection + +(This appendix does not form an integral part of this Recommendation.) + +### II.1 Introduction + +Protection architectures and solutions with XG(S)-PON REs are possible. However, XG(S)-PON reach extension can have an impact on reliability. Due to long link length, the risk of fibre damage is higher, and so in many cases the OTL might have to be protected. + +On the other hand, XG(S)-PON reach extension enables OLT-geo-redundancy, which is not yet fully standardized. This geographic redundancy is also termed "dual homing". The control and signalling of the dual-homing schemes are for future study. + +## II.2 RE-independent type B protection + +Figure II.1 gives an example of a protected reach extended XG(S)-PON. In this case, the OTL and mid-span REs are duplicated (protected), and the ODN implements the classical type-B 2:N splitting connection. In this scenario, the REs require a control input such that only the working RE transmits in the downstream, and the protecting RE suppresses its transmission. This can be accomplished most easily by constructing the RE such that if the signal from the OLT is suppressed, then the RE downstream output will also be suppressed. + +![Diagram of a reach extended XG(S)-PON with geo-redundant OLT and trunk line protection. The diagram shows two parallel paths. Each path consists of an ONU connected to a Splitter 2:N via its R/S interface. The Splitter 2:N is connected to a Mid-span extender via its S'/R' interface. The Mid-span extender is connected to an OLT via its R'/S' interface. The OLT is connected to another OLT via its S/R interface. The second OLT is connected to an SNI via its SNI interface. The first OLT is also connected to the UNI interface of the ONU. The second OLT is also connected to the UNI interface of the ONU. The diagram is labeled G.9807.2(17)_FII.1.](1ad662a678c4f002de911d403f00de8e_img.jpg) + +The diagram illustrates a reach extended XG(S)-PON architecture with geo-redundant OLT and trunk line protection. It features two parallel optical paths. Each path starts with an ONU connected to a Splitter 2:N via its R/S interface. The Splitter 2:N is connected to a Mid-span extender via its S'/R' interface. The Mid-span extender is connected to an OLT via its R'/S' interface. The OLT is connected to another OLT via its S/R interface. The second OLT is connected to an SNI via its SNI interface. The first OLT is also connected to the UNI interface of the ONU. The second OLT is also connected to the UNI interface of the ONU. The diagram is labeled G.9807.2(17)\_FII.1. + +Diagram of a reach extended XG(S)-PON with geo-redundant OLT and trunk line protection. The diagram shows two parallel paths. Each path consists of an ONU connected to a Splitter 2:N via its R/S interface. The Splitter 2:N is connected to a Mid-span extender via its S'/R' interface. The Mid-span extender is connected to an OLT via its R'/S' interface. The OLT is connected to another OLT via its S/R interface. The second OLT is connected to an SNI via its SNI interface. The first OLT is also connected to the UNI interface of the ONU. The second OLT is also connected to the UNI interface of the ONU. The diagram is labeled G.9807.2(17)\_FII.1. + +**Figure II.1 – Reach extended XG(S)-PON, with geo-redundant OLT and trunk line protection** + +## II.3 OEO extender-based type B protection + +Figure II.2 shows the architecture of an OEO-based reach extended PON with a type B protection function. In this case, the type B 2:N junction point is inside the RE. The protection switch function is done by an integrated MUX module within the E-ONU MAC. Once the E-ONU is powered up, the inner MUX module, controlled by the E-ONU MAC, chooses to pass the signal from the Tx/Rx set at the R'/S' side connecting with the working OLT. Then the E-ONU registers to this OLT as well as all of the other downstream ONUs. Then the system enters the normal working state as usual. + +![Figure II.2: OEO-based LR PON with type B protection: integrated MUX module. The diagram shows a central E-ONU MAC connected to two optical paths. Each path consists of a transmitter (Tx), a diplexer, and a receiver (Rx). The Tx and Rx are connected to the E-ONU MAC via summing nodes (circles with a plus sign). The diplexers are connected to the summing nodes and to the R'/S' ports. The diagram is labeled G.9807.2(17)_FII.2.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +Figure II.2: OEO-based LR PON with type B protection: integrated MUX module. The diagram shows a central E-ONU MAC connected to two optical paths. Each path consists of a transmitter (Tx), a diplexer, and a receiver (Rx). The Tx and Rx are connected to the E-ONU MAC via summing nodes (circles with a plus sign). The diplexers are connected to the summing nodes and to the R'/S' ports. The diagram is labeled G.9807.2(17)\_FII.2. + +**Figure II.2 – OEO-based LR PON with type B protection: integrated MUX module** + +## II.4 OA-extender-based type B protection architecture + +Figure II.3 shows the architecture of an OA-based LR PON with a type B protection function. In this case, the 2:N function is done by an external MUX module at the R'/S' side. Though the RE feature is implemented through an optical amplifier, it works in a similar way to the architecture shown in Figure II.2. + +![Figure II.3: OA-based LR PON with type B protection: external MUX module. The diagram shows a central E-ONU MAC connected to a local controller and a diplexer. The diplexer is connected to a 2:2 splitter. The 2:2 splitter is connected to two R'/S' ports. The E-ONU MAC is also connected to a transmitter (Tx) and a receiver (Rx). The Tx and Rx are connected to the diplexer. The diplexer is also connected to a U/S amplifier and a D/S amplifier. The U/S amplifier is connected to a diplexer, which is connected to the S'/R' port. The D/S amplifier is connected to the diplexer. The diagram is labeled G.9807.2(17)_FII.3.](04cfca33e3fc26513abe649d7474f733_img.jpg) + +Figure II.3: OA-based LR PON with type B protection: external MUX module. The diagram shows a central E-ONU MAC connected to a local controller and a diplexer. The diplexer is connected to a 2:2 splitter. The 2:2 splitter is connected to two R'/S' ports. The E-ONU MAC is also connected to a transmitter (Tx) and a receiver (Rx). The Tx and Rx are connected to the diplexer. The diplexer is also connected to a U/S amplifier and a D/S amplifier. The U/S amplifier is connected to a diplexer, which is connected to the S'/R' port. The D/S amplifier is connected to the diplexer. The diagram is labeled G.9807.2(17)\_FII.3. + +**Figure II.3 – OA-based LR PON with type B protection: external MUX module** + +# Appendix III + +## Optical time domain reflectometer + +(This appendix does not form an integral part of this Recommendation.) + +## III.1 Introduction + +Optical time domain reflectometer (OTDR) monitoring pulses may disturb the operation of the RE and, on the other hand, the presence of an RE blocks the propagation of the OTDR signals. + +### III.2 Solution + +Figure III.1 gives one example of an extended XG(S)-PON equipped with OTDR blocking filters or bypass filters. In both cases, insertion loss of the blocking or bypass filters has to be accounted into the OTL or the ODN loss. In case of bypass, the reach limit of the OTDR in use requires consideration. + +![Figure III.1 shows two diagrams of a reach extender configuration. The top diagram shows an ODN connected to an OTDR BF, which is connected to a Mid-span extender, which is connected to an OTL via another OTDR BF. The bottom diagram shows an ODN connected to an OTDR BYP, which is connected to a Mid-span extender, which is connected to an OTL via another OTDR BYP. Both diagrams include labels S'/R' and R'/S' at the interfaces.](9f862801bce82634d3b5a1e0a195a799_img.jpg) + +The diagram illustrates two configurations for a reach extender in an optical network. Both configurations consist of an Optical Distribution Network (ODN) on the left and an Optical Transport Line (OTL) on the right, connected by a central 'Mid-span extender' block. In the top configuration, the ODN is connected to an 'OTDR BF' (blocking filter), which is then connected to the Mid-span extender via an interface labeled 'S'/R''. The Mid-span extender is connected to another 'OTDR BF', which is then connected to the OTL via an interface labeled 'R'/S''. In the bottom configuration, the ODN is connected to an 'OTDR BYP' (bypass filter), which is connected to the Mid-span extender via an interface labeled 'S'/R''. The Mid-span extender is connected to another 'OTDR BYP', which is then connected to the OTL via an interface labeled 'R'/S''. The label 'G.9807.2(17)\_FIII.1' is present at the bottom right of the diagram. + +Figure III.1 shows two diagrams of a reach extender configuration. The top diagram shows an ODN connected to an OTDR BF, which is connected to a Mid-span extender, which is connected to an OTL via another OTDR BF. The bottom diagram shows an ODN connected to an OTDR BYP, which is connected to a Mid-span extender, which is connected to an OTL via another OTDR BYP. Both diagrams include labels S'/R' and R'/S' at the interfaces. + +**Figure III.1 – Reach extender with OTDR blocking filters (BF) and OTDR bypass (BYP) filters** + +# Appendix IV + +## Transport of BM-to-CM converted signals over OTN + +(This appendix does not form an integral part of this Recommendation.) + +The use of BM-to-CM enabled RE functions opens a new possibility: transporting the resulting continuous mode signals over the optical transport network (OTN). The basic system arrangement is shown in Figure IV.1. + +![Figure IV.1: The transport of BM-to-CM signals over OTN. The diagram shows a signal flow from left to right. On the far left, an optical interface labeled S'/R' connects to a 'BM to CM RE' unit. This unit outputs an R''/S'' signal. This signal is then processed through two parallel paths: one through an 'Encode' block (with a mapping 0→1000, 1→1110) followed by an 'ITU-T G.709 Map' block, and another through an 'ITU-T G.709 Demap' block. Both paths converge into a central 'OTN' block, which is flanked by 'ODU2' labels. From the OTN block, the signal passes through another 'ITU-T G.709 Map' block and an 'ITU-T G.709 Demap' block. These lead to a 'Decode' block (with a mapping 1000→0, 1110→1), which then connects to a 'CM to BM' unit. The final output on the far right is an S''/R'' signal. A central box labeled 'CBR signal 9.95328 ± 32 ppm' has arrows pointing to the 'Encode' and 'Decode' blocks, indicating the constant bit rate signal being transported.](f5deee2f3301ee351c4008283ffafbb3_img.jpg) + +The diagram illustrates the transport of BM-to-CM signals over OTN. On the left, an optical interface (S'/R') connects to a BM to CM RE unit. The RE unit outputs an R''/S'' signal. This signal is then processed through two parallel paths: one through an 'Encode' block (with a mapping 0→1000, 1→1110) followed by an 'ITU-T G.709 Map' block, and another through an 'ITU-T G.709 Demap' block. Both paths converge into a central 'OTN' block, which is flanked by 'ODU2' labels. From the OTN block, the signal passes through another 'ITU-T G.709 Map' block and an 'ITU-T G.709 Demap' block. These lead to a 'Decode' block (with a mapping 1000→0, 1110→1), which then connects to a 'CM to BM' unit. The final output on the right is an S''/R'' signal. A central box labeled 'CBR signal 9.95328 ± 32 ppm' has arrows pointing to the 'Encode' and 'Decode' blocks, indicating the constant bit rate signal being transported. + +Figure IV.1: The transport of BM-to-CM signals over OTN. The diagram shows a signal flow from left to right. On the far left, an optical interface labeled S'/R' connects to a 'BM to CM RE' unit. This unit outputs an R''/S'' signal. This signal is then processed through two parallel paths: one through an 'Encode' block (with a mapping 0→1000, 1→1110) followed by an 'ITU-T G.709 Map' block, and another through an 'ITU-T G.709 Demap' block. Both paths converge into a central 'OTN' block, which is flanked by 'ODU2' labels. From the OTN block, the signal passes through another 'ITU-T G.709 Map' block and an 'ITU-T G.709 Demap' block. These lead to a 'Decode' block (with a mapping 1000→0, 1110→1), which then connects to a 'CM to BM' unit. The final output on the far right is an S''/R'' signal. A central box labeled 'CBR signal 9.95328 ± 32 ppm' has arrows pointing to the 'Encode' and 'Decode' blocks, indicating the constant bit rate signal being transported. + +Figure IV.1 – The transport of BM-to-CM signals over OTN + +In the downstream direction, the CM-to-BM unit performs a null function (i.e., the output of the OLT is already a continuous mode signal). The CMXGSPON\_D signal is a 9.953 28 Gbit/s constant bit rate signal, and it has a frequency accuracy no worse than 32 ppm (corresponding to an OLT that is operating in free running mode, per Annex B of [ITU-T G.9807.1]). In fact, in normal operation, the frequency accuracy should be 4.6 ppm or better. [b-ITU-T G.709] describes how to map the CMXGSPON\_D signal into an ODU2, and how to de-map (recover) the signal on the other side. The BM-to-CM unit performs a null function again, and merely passes the continuous mode signal on to the optical interface. + +In the upstream, the BM-to-CM unit converts the upstream bursts into a continuous mode signal (CMXGSPON\_U), as described in clause 6.2. The CMXGSPON\_U signal is a 9.953 28 Gbit/s or 2.488 32 Gbit/s bit rate signal that is synchronous with the downstream signal and it has a frequency accuracy no worse than the downstream signal (per Annex B of [ITU-T G.9807.1]). A trivial encoding is used to convert this into a 9.953 28 Gbit/s signal (denoted CMXGSPON\_U2). This encoding converts an input 0 into 1000, and an input 1 into 1110. The decoder performs the reverse conversion. [b-ITU-T G.709] describes how to map the CMXGSPON\_U2 signal into an ODU2, and how to recover it on the other side. The CM-to-BM unit converts the upstream continuous mode signal back into a burst-like signal, and passes this to the OLT. + +# Appendix V + +## Possible realization of OA and OEO-based extenders using wavelength conversion + +(This appendix does not form an integral part of this Recommendation.) + +This appendix illustrates examples of several implementations of WC extenders. + +## V.1 A transparent wavelength plan extender realization + +Figures V.1 and V.2 are schematic diagrams for examples of the optical WC RE and WC OLT, respectively, for a transparent WC design. + +![Schematic diagram of a transparent wavelength conversion reach extender (Figure V.1). The diagram shows the signal flow between S'/R' and R''/S'' interfaces. It includes diplexers, Rx_up and Tx_up blocks for wavelength conversion, WDM multiplexer and demultiplexer, an optical amplifier for downstream, a tap, an EONU, and a local controller. Upstream signals λ_U are converted to λ_U_OTL, and downstream signals λ_D_OTL are processed through an optical amplifier.](8c880d6b715587bd710a9ba8414469b1_img.jpg) + +``` + +graph LR + subgraph "S'/R' Interface" + SD[λ_D] --> Dip1[Diplexer] + Dip1 --> SU[λ_U] + SD2[λ_D] --> Tap[Tap] + Tap --> Dip2[Diplexer] + Dip2 --> SU2[λ_U] + end + + Tap --> EONU[EONU] + EONU <--> LC[Local controller] + LC --> Rx1[Rx_up] + LC --> Tx1[Tx_up] + LC --> Rx2[Rx_up] + LC --> Tx2[Tx_up] + + Dip1 --> Rx1 + Rx1 -- clk --> Tx1 + Tx1 -- λ_U_OTL --> WDM_M[WDM multiplexer] + + Dip2 --> Rx2 + Rx2 -- clk --> Tx2 + Tx2 -- λ_U_OTL --> WDM_M + + WDM_M --> Dip3[Diplexer] + Dip3 --> RS_Out[λ_U_OTL] + RS_In[λ_D_OTL] --> Dip3 + Dip3 --> OA[Optical Amp. RE_downstream] + OA --> WDM_D[WDM demultiplexer] + WDM_D -- λ_D_OTL --> Dip1 + WDM_D -- λ_D_OTL --> Dip2 + + subgraph "R''/S'' Interface" + RS_Out + RS_In + end + +``` + +G.9807.2(17)\_FV.1 + +Schematic diagram of a transparent wavelength conversion reach extender (Figure V.1). The diagram shows the signal flow between S'/R' and R''/S'' interfaces. It includes diplexers, Rx\_up and Tx\_up blocks for wavelength conversion, WDM multiplexer and demultiplexer, an optical amplifier for downstream, a tap, an EONU, and a local controller. Upstream signals λ\_U are converted to λ\_U\_OTL, and downstream signals λ\_D\_OTL are processed through an optical amplifier. + +**Figure V.1 – Example of a transparent wavelength conversion reach extender** + +The RE upstream Rx and Tx should be enhanced in the same way as in clause 6.2 (OEO-based RE) to support dual rate operation in the XG(S)-PON. In addition, the RE upstream Tx should also be able to convert the received upstream wavelength into a different one, to support wavelength multiplexing at the upstream WDM. Either coloured or tunable Tx technology can fulfil this function. + +![Figure V.2: Example of a transparent wavelength conversion OLT. The diagram shows an optical network architecture with two main paths. The top path consists of a WDM multiplexer connected to a series of optical transceivers (Tx_down, Rx_down) which are controlled by a clock (clk). These transceivers are connected to a Diplexer, which is then connected to a Tap. The bottom path consists of a WDM demultiplexer connected to a series of optical transceivers (Tx_down, Rx_down) controlled by a clock (clk). These transceivers are connected to a Diplexer, which is then connected to an EONU, which is in turn connected to a Local controller. The diagram also shows various wavelength labels: λ_D_OTL, λ_U_OTL, λ_D, λ_U, and S](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +Figure V.2: Example of a transparent wavelength conversion OLT. The diagram shows an optical network architecture with two main paths. The top path consists of a WDM multiplexer connected to a series of optical transceivers (Tx\_down, Rx\_down) which are controlled by a clock (clk). These transceivers are connected to a Diplexer, which is then connected to a Tap. The bottom path consists of a WDM demultiplexer connected to a series of optical transceivers (Tx\_down, Rx\_down) controlled by a clock (clk). These transceivers are connected to a Diplexer, which is then connected to an EONU, which is in turn connected to a Local controller. The diagram also shows various wavelength labels: λ\_D\_OTL, λ\_U\_OTL, λ\_D, λ\_U, and S + +**Figure V.2 – Example of a transparent wavelength conversion OLT** + +The chief advantage of the transparent WC system is that the wavelength re-conversion at the receiving end of the OTL is avoided. In the downstream, all that is needed at the RE is an optical amplifier. This is particularly advantageous in cases where this amplifier can handle all of the wavelength channels at once. In the upstream at the WC-OLT, just a passive WDM is used to direct the channels to the appropriate OLT port. On the transmitting end of the OTL, any means of WC is possible; in the example here, OEO conversion is used. + +## V.2 A conventional wavelength plan extender realization + +Figures V.3 and V.4 are schematic diagrams for examples of the optical WC RE and WC OLT, respectively, for a conventional WC design. This is perhaps the most straightforward type of WC, where both directions of the PON signals are converted to the conventional ITU-T G.694-series wavelength options, and back again. This example shows OEO WC technology, but other types of conversion are possible. This example also shows the use of BM-to-CM conversion and re-conversion. This allows for the use of more common CM optics, but this is not essential. + +![Figure V.3: Example of a conventional wavelength conversion reach extender. The diagram shows a network architecture with multiple user-side interfaces (S'/R') on the left and a central core interface (R''/S'') on the right. Each user interface connects to a Diplexer. One path from the Diplexer goes through a receiver (Rx_up), a BM-to-CM converter, and a transmitter (Tx_up) to produce an upstream wavelength (lambda_U_1, lambda_U_N). Another path goes through a transmitter (Tx_down), a receiver (Rx_down), and a clock (clk) to produce a downstream wavelength (lambda_D_1, lambda_D_N). These signals are then multiplexed by a WDM multiplexer and demultiplexer. An EONU and a Local controller are connected to the system. The central interface on the right shows OTL wavelengths (lambda_D_OTL, lambda_U_OTL) being processed by another Diplexer. The diagram is labeled G.9807.2(17)_FV.3.](798679874d1c29f8343506a156c79d7e_img.jpg) + +Figure V.3: Example of a conventional wavelength conversion reach extender. The diagram shows a network architecture with multiple user-side interfaces (S'/R') on the left and a central core interface (R''/S'') on the right. Each user interface connects to a Diplexer. One path from the Diplexer goes through a receiver (Rx\_up), a BM-to-CM converter, and a transmitter (Tx\_up) to produce an upstream wavelength (lambda\_U\_1, lambda\_U\_N). Another path goes through a transmitter (Tx\_down), a receiver (Rx\_down), and a clock (clk) to produce a downstream wavelength (lambda\_D\_1, lambda\_D\_N). These signals are then multiplexed by a WDM multiplexer and demultiplexer. An EONU and a Local controller are connected to the system. The central interface on the right shows OTL wavelengths (lambda\_D\_OTL, lambda\_U\_OTL) being processed by another Diplexer. The diagram is labeled G.9807.2(17)\_FV.3. + +**Figure V.3 – Example of a conventional wavelength conversion reach extender** + +The RE upstream RX and TX should be enhanced in a similar way to that in clause 6.2 (OEO-based RE) to support dual rate operation in the XG(S)-PON. In addition, the RE upstream TX should also be able to convert the received upstream wavelength into a different one, to support wavelength multiplexing at the upstream WDM. Either coloured or tunable TX technology can fulfil this function. + +![Figure V.4: Example of a conventional wavelength conversion OLT. This diagram shows the OLT side of the network. On the right, user-side interfaces (S/R) connect to a Tap, which then connects to a Diplexer. This Diplexer feeds into a WDM demultiplexer. The WDM demultiplexer outputs are connected to transceivers: Rx_up, BM-to-CM, Tx_up for upstream signals (lambda_U_1, lambda_U_N) and Tx_down, Rx_down, clk for downstream signals (lambda_D_1, lambda_D_N). These signals are then multiplexed by a WDM multiplexer. The WDM multiplexer connects to another Diplexer, which outputs the OTL wavelengths (lambda_D_OTL, lambda_U_OTL) on the left (S''/R''). An EONU and a Local controller are also connected to the system. The diagram is labeled G.9807.2(17)_FV.4.](8269648391c59363ea61243864a2adf7_img.jpg) + +Figure V.4: Example of a conventional wavelength conversion OLT. This diagram shows the OLT side of the network. On the right, user-side interfaces (S/R) connect to a Tap, which then connects to a Diplexer. This Diplexer feeds into a WDM demultiplexer. The WDM demultiplexer outputs are connected to transceivers: Rx\_up, BM-to-CM, Tx\_up for upstream signals (lambda\_U\_1, lambda\_U\_N) and Tx\_down, Rx\_down, clk for downstream signals (lambda\_D\_1, lambda\_D\_N). These signals are then multiplexed by a WDM multiplexer. The WDM multiplexer connects to another Diplexer, which outputs the OTL wavelengths (lambda\_D\_OTL, lambda\_U\_OTL) on the left (S''/R''). An EONU and a Local controller are also connected to the system. The diagram is labeled G.9807.2(17)\_FV.4. + +**Figure V.4 – Example of a conventional wavelength conversion OLT** + +## V.3 An OWC based extender realization + +Figures V.5 and V.6 are schematic diagrams for examples of the optical WC RE and WC OLT, respectively, for an optical WC design. The main advantage of optical WC is that it can be independent of PON signal data rate and protocol format. From a certain point of view, this is more "passive" than other types of WC. + +![Figure V.5: Example of an optical wavelength conversion reach extender. The diagram shows a network architecture where signals from an S/R' interface are split by a Tap. One path goes through a Diplexer to an OWC_up unit (converting λ_U to λ_U_1) and an OWC_down unit (converting λ_D to λ_D_1). These signals are then multiplexed by a WDM multiplexer. The second path from the Tap goes through another Diplexer to an OWC_up unit (converting λ_U to λ_U_N) and an OWC_down unit (converting λ_D to λ_D_N), which are multiplexed by a WDM demultiplexer. Both WDM units are connected to a central Diplexer, which outputs to an R''/S'' interface with wavelengths λ_D_OTL and λ_U_OTL. An EONU and a Local controller are connected to the bottom Diplexer.](f5a5f52bc25d95a7f616290c99e88ae6_img.jpg) + +G.9807.2(17)\_FV.5 + +Figure V.5: Example of an optical wavelength conversion reach extender. The diagram shows a network architecture where signals from an S/R' interface are split by a Tap. One path goes through a Diplexer to an OWC\_up unit (converting λ\_U to λ\_U\_1) and an OWC\_down unit (converting λ\_D to λ\_D\_1). These signals are then multiplexed by a WDM multiplexer. The second path from the Tap goes through another Diplexer to an OWC\_up unit (converting λ\_U to λ\_U\_N) and an OWC\_down unit (converting λ\_D to λ\_D\_N), which are multiplexed by a WDM demultiplexer. Both WDM units are connected to a central Diplexer, which outputs to an R''/S'' interface with wavelengths λ\_D\_OTL and λ\_U\_OTL. An EONU and a Local controller are connected to the bottom Diplexer. + +Figure V.5 – Example of an optical wavelength conversion reach extender + +![Figure V.6: Example of an optical wavelength conversion OLT. This diagram shows the reverse architecture of Figure V.5. Signals from an S''/R'' interface pass through a Diplexer and are split by a WDM multiplexer and a WDM demultiplexer. The WDM multiplexer feeds into an OWC_down unit (converting λ_D_1 to λ_D) and an OWC_up unit (converting λ_U_1 to λ_U), which are then combined by a Diplexer. The WDM demultiplexer feeds into an OWC_down unit (converting λ_D_N to λ_D) and an OWC_up unit (converting λ_U_N to λ_U), which are combined by another Diplexer. These two paths are then split by a Tap, with one output going to an S/R interface and the other to an EONU connected to a Local controller. The top Diplexer outputs to an interface with wavelengths λ_D_OTL and λ_U_OTL.](cf8bd014a50b7c69435e804f67f9617f_img.jpg) + +G.9807.2(17)\_FV.6 + +Figure V.6: Example of an optical wavelength conversion OLT. This diagram shows the reverse architecture of Figure V.5. Signals from an S''/R'' interface pass through a Diplexer and are split by a WDM multiplexer and a WDM demultiplexer. The WDM multiplexer feeds into an OWC\_down unit (converting λ\_D\_1 to λ\_D) and an OWC\_up unit (converting λ\_U\_1 to λ\_U), which are then combined by a Diplexer. The WDM demultiplexer feeds into an OWC\_down unit (converting λ\_D\_N to λ\_D) and an OWC\_up unit (converting λ\_U\_N to λ\_U), which are combined by another Diplexer. These two paths are then split by a Tap, with one output going to an S/R interface and the other to an EONU connected to a Local controller. The top Diplexer outputs to an interface with wavelengths λ\_D\_OTL and λ\_U\_OTL. + +Figure V.6 – Example of an optical wavelength conversion OLT + +One possible implementation of an optical wavelength converter is the so-called all-optical wavelength converter (AOWC) device. The AOWC device can be constructed from the following components: + +- Input fibre, which guides input signal into AOWC; + +- SOA based fibre-grating external-cavity laser, operating at wavelength $\lambda_2$ , responsible for the WC function; +- Output fibre, which guides the wavelength-converted signal out of the AOWC unit. + +The operating principle can be described as follows. + +The input optical fibre guides the non-return to zero (NRZ) input signal at wavelength $\lambda_1$ into the SOA unit. The amplitude-modulated NRZ input signal at wavelength $\lambda_1$ is amplified and the output optical power at wavelength $\lambda_2$ is suppressed simultaneously by cross-gain modulation (XGM) effect. The output optical power at wavelength $\lambda_2$ is modulated by the input signal power and the input NRZ signal is wavelength converted from wavelength $\lambda_1$ to wavelength $\lambda_2$ with reversed digital levels (logical "1" is equivalent to low light level). The output fibre guides the wavelength-converted signal at wavelength $\lambda_2$ out of the AOWC. A WDM multiplexer/demultiplexer or arrayed waveguide grating (AWG) located outside the AOWC, acting as a wavelength selective filter, blocks the input signal at wavelength $\lambda_1$ and only allow the wavelength-converted signal at wavelength $\lambda_2$ to pass through. + +## Bibliography + +- [b-ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016), *Interfaces for the optical transport network*. +- [b-ITU-T G.987.4] Recommendation ITU-T G.987.4 (2012), *10-Gigabit-capable passive optical networks (XG-PON): Reach extension*. +- [b-Cheng] Cheng N., Liao, Z., Effenberger, F.J. (2010). Large splitting and long reach passive optical networks with mode coupling receivers (Tu 5B3), *ECOC*. New York, NY:IEEE. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for 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survivability** + +ITU-T Recommendation G.983.5 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# **ITU-T Recommendation G.983.5** + +# **A broadband optical access system with enhanced survivability** + +# **Summary** + +This Recommendation describes flexible access networks using optical fibre technology based on ITU-T Rec. G.983.1. Specifically, it describes the functions that extend ITU-T Rec. G.983.1 to enable survivability-protection enhancements for the delivery of highly reliable services. It describes B-PON survivability architectures, protection performance criteria, and protection-switching criteria and protocols. + +###### **Source** + +ITU-T Recommendation G.983.5 was prepared by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 6 January 2002. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2002 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +###### Page + +| | | | +|-------|----------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Abbreviations..... | 2 | +| 4 | Definitions ..... | 4 | +| 5 | Architecture and requirements for a protected optical access network ..... | 5 | +| 5.1 | Architecture and requirements ..... | 5 | +| 5.1.1 | Service categories..... | 5 | +| 5.1.2 | Background and requirements ..... | 5 | +| 5.2 | Reference configuration ..... | 8 | +| 5.3 | Functional blocks..... | 8 | +| 5.4 | ONU functional block ..... | 8 | +| 5.4.1 | Optical Distribution Network (ODN) interface..... | 8 | +| 5.4.2 | Multiplexing ..... | 9 | +| 5.4.3 | User Port..... | 9 | +| 5.4.4 | ONU Powering ..... | 9 | +| 5.4.5 | ODN interface switch ..... | 9 | +| 5.5 | OLT functional block ..... | 9 | +| 5.6 | Optical Distribution Network (ODN) functional block..... | 11 | +| 5.6.1 | Passive optical elements ..... | 11 | +| 5.6.2 | Optical interfaces..... | 11 | +| 6 | Services..... | 13 | +| 7 | User Network Interface and Service Node Interface..... | 13 | +| 8 | Optical network survivability requirements ..... | 13 | +| 8.1 | Layer structure of the B-PON survivability optical network ..... | 13 | +| 8.2 | Physical medium dependent layer requirements for B-PON ..... | 15 | +| 8.3 | Additional TC-layer requirements for B-PON survivability..... | 15 | +| 8.3.1 | Duplex PON link identification..... | 15 | +| 8.3.2 | Additional messages in the PLOAM channel for survivability..... | 16 | +| 8.3.3 | Message formats..... | 16 | +| 8.4 | Ranging Method ..... | 17 | +| 8.5 | Protection switching ..... | 17 | +| 8.5.1 | PON Protection function ..... | 17 | +| 8.5.2 | Protocols ..... | 19 | +| 8.5.3 | Switching criteria..... | 19 | +| 8.5.4 | Performance..... | 20 | + +| | | | +|---------|-----------------------------------------------------------------------------------------|----| +| 9 | Operations Administration and Maintenance (OAM) functionality..... | 22 | +| 10 | Performance..... | 22 | +| 11 | Environmental condition ..... | 22 | +| 12 | Safety ..... | 22 | +| Annex A | – Fast switching protocol for the B-PON access network ..... | 22 | +| A.1 | Survivability Architecture ..... | 22 | +| A.1.1 | 1:1 architecture (required) ..... | 22 | +| A.1.2 | 1+1 Architecture (optional) ..... | 23 | +| A.2 | MSP bytes..... | 24 | +| A.2.1 | K1 byte ..... | 24 | +| A.2.2 | K1 byte generation rules..... | 24 | +| A.2.3 | Revertive/non-revertive modes ..... | 24 | +| A.2.4 | K2 byte ..... | 25 | +| A.2.5 | Control of the upstream switch in the ONU and the downstream switch in
the OLT ..... | 25 | +| A.2.6 | Transmission and acceptance of MSP Bytes..... | 25 | +| A.3 | MSP commands..... | 25 | +| A.4 | Switching Sequence..... | 25 | +| A.4.1 | 1:1 bidirectional operation with non-revertive mode ..... | 25 | +| A.4.2 | 1:1 bidirectional operation with revertive mode ..... | 43 | +| A.4.3 | 1+1 bidirectional operation with non-revertive mode ..... | 46 | +| A.4.4 | 1+1 bidirectional operation with revertive mode ..... | 49 | + +# A broadband optical access system with enhanced survivability + +# 1 Scope + +This Recommendation describes the extended functions for B-PON systems defined in ITU-T Rec. G.983.1 to enable protection functions. It is based on Appendix IV/G.983.1. In particular, it focuses on the protection-configuration types B and C described in that appendix. + +This Recommendation discusses a number of protection feature and function choices and provides the necessary specifications in the PON layer to implement these choices. These include guidelines on performance objectives (for example, switching and detection time), application functionality (for example, revertive mode, non-revertive mode, extra traffic support, automatic switching, and forced switching), switching criteria and switching protocols (1+1, 1:1, 1:N, bidirectional and unidirectional mechanisms). + +This Recommendation considers protection enhancements for the delivery of highly reliable services for a variety of B-PON network scenarios, including Fibre to the Cabinet (FTTCab) and Fibre to the Office (FTTO). + +# 2 References + +The following ITU-T Recommendations and other references contain provisions, which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.652 (2000), *Characteristics of a single-mode optical fibre cable*. +- [2] ITU-T Recommendation G.671 (2001), *Transmission characteristics of optical components and subsystems*. +- [3] ITU-T Recommendation G.783 (2000), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks*. +- [4] ITU-T Recommendation G.841 (1998), *Types and characteristics of SDH network protection architectures*. +- [5] ITU-T Recommendation G.902 (1995), *Framework recommendation on functional access networks (AN) – Architecture and functions, access types, management and service node aspects*. +- [6] ITU-T Recommendation G.957 (1999), *Optical interfaces for equipment and systems relating to the synchronous digital hierarchy*. +- [7] ITU-T Recommendation G.958 (1994), *Digital line systems based on the synchronous digital hierarchy for use on optical fibre cables*. +- [8] ITU-T Recommendation G.982 (1996), *Optical access networks to support services up to the ISDN primary rates or equivalent bit rates*. +- [9] ITU-T G.983.1 (1998), *Broadband optical access systems based on Passive Optical Networks (PON)*. + +- [10] ITU-T G.983.2 (2000), *The ONT management and control interface specification for ATM PON.* +- [11] ITU-T I.321 (1991), *B-ISDN protocol reference model and its application.* +- [12] ITU-T I.326 (1995), *Functional architecture of transport networks based on ATM.* +- [13] ITU-T I.356 (2000), *B-ISDN ATM layer cell transfer performance.* +- [14] ITU-T I.361 (1999), *B-ISDN ATM layer specification.* +- [15] ITU-T I.432.1 (1999), *B-ISDN user-network interface – Physical layer specification: General characteristics.* +- [16] ITU-T I.610 (1999), *B-ISDN operation and maintenance principles and functions.* +- [17] ITU-T I.732 (2000), *Functional characteristics of ATM equipment.* + +# 3 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|--------|-----------------------------------------------| +| AF | Adaptation Function | +| APS | Automatic Protection Switching | +| ATM | Asynchronous Transfer Mode | +| BER | Bit Error Ratio | +| BIP | Bit Interleaved Parity | +| B-ISDN | Broadband Integrated Services Digital Network | +| B-PON | Broadband Passive Optical Network | +| CID | Consecutive Identical Digit | +| CPE | Cell Phase Error | +| CRC | Cyclic Redundancy Check | +| DSL | Digital Subscriber Line | +| E/O | Electrical/Optical | +| FTTB/C | Fibre to the Building/Curb | +| FTTCab | Fibre to the Cabinet | +| FTTH | Fibre to the Home | +| FTTO | Fibre to the Office | +| HEC | Header Error Control | +| IEC | International Electrotechnical Commission | +| ISDN | Integrated Services Digital Network | +| LAN | Local Area Network | +| LCD | Loss of Cell Delineation | +| LCF | Laser Control Field | +| LSB | Least Significant Bit | +| LT | Line Terminal | +| MAC | Media Access Control | + +| | | +|-------|-------------------------------------------| +| MSB | Most Significant Bit | +| MSP | Multiplex Section Protection | +| NT | Network Termination | +| OAM | Operation, Administration and Maintenance | +| OAN | Optical Access Network | +| ODF | Optical Distribution Frame | +| ODN | Optical Distribution Network | +| OLT | Optical Line Termination | +| ONT | Optical Network Termination | +| ONU | Optical Network Unit | +| OpS | Operations System | +| PLOAM | Physical Layer OAM | +| PON | Passive Optical Network | +| PRBS | Pseudo-Random Bit Sequence | +| PST | PON Section Trace | +| PSTN | Public Switched Telephone Network | +| QoS | Quality of Service | +| RAU | Request Access Unit | +| RMS | Root Mean Square | +| SD | Signal Degrade | +| SDH | Synchronous Digital Hierarchy | +| SF | Signal Fail | +| SN | Serial Number | +| SNI | Service Node Interface | +| SPC | Service Port Function | +| TC | Transmission Convergence | +| TDMA | Time Division Multiple Access | +| UI | Unit Interval | +| UNI | User Network Interface | +| UPC | Usage Parameter Control | +| UPF | User Port Function | +| VC | Virtual Channel | +| VoD | Video on Demand | +| VP | Virtual Path | +| VPI | Virtual Path Identifier | +| WDM | Wavelength Division Multiplexing | + +# 4 Definitions + +This Recommendation defines the following terms: + +**4.1 1:1 protection:** A system of 1:1 protection configuration carries traffic in the working equipment while the protection equipment stands by without serving any traffic. The 1:1 protection configuration is a special case of the more general 1:N protection where the protection equipment is shared among N sets of working equipment. + +**4.2 1+1 protection:** A system of 1+1 protection configuration carries identical traffic in both working and protection equipment. + +**4.3 X:N protection architecture:** A system of X:N protection architecture offers X protection PONs for N working PONs, where some or all of the protected ONUs on the working PONs can be connected to any of the X protection PONs. + +**4.4 bidirectional protection:** Upon detecting a failure of its working equipment, a system of bidirectional protection configuration requires acknowledgement from the far-end protection equipment before switching to the protection equipment. + +**4.5 unidirectional protection:** A system of unidirectional protection configuration can switch to protection equipment once it detects failure in its working equipment. + +**4.6 churning:** Churning is a function that can be applied to the downstream user data from an OLT to its ONUs. Churning provides the necessary function of data scrambling and offers a low level of protection for data confidentiality. It is installed at the TC layer of the B-PON system and can be activated for point-to-point downstream connections. + +**4.7 duplex working:** Bidirectional communication using a different wavelength for each direction of transmission over a single fibre. + +**4.8 extra traffic:** Lower priority traffic with respect to that being carried by the working entity. It is carried over the protection entity while the working entity is active. The extra traffic is not protected, i.e. when the protection entity is required to protect the traffic that is being carried over the working entity (due to a failure or forced/manual switch operation), the extra traffic is pre-empted. + +**4.9 grant:** A grant is a short downstream message giving permission to a specific ONU to transmit an upstream cell. The OLT controls the distribution of grants to the ONUs and ensures good use of the upstream channel without data collisions. + +**4.10 mean signal transfer delay:** The average upstream and downstream values between reference points "V" and "T", a given value is determined by measuring round-trip delay, then dividing by 2. + +**4.11 non-revertive:** A protection configuration is non-revertive if the system does not switch back. + +**4.12 Optical Access Network (OAN):** The set of access links sharing the same network-side interfaces and supported by optical access transmission systems. The OAN may include a number of ODNs connected to the same OLT. + +**4.13 Optical Distribution Network (ODN):** An ODN provides the optical transmission means from the OLT towards the users, and vice versa. It utilises passive optical components. + +**4.14 Optical Line Termination (OLT):** An OLT provides the network-side interface of the OAN, and is connected to one or more ODNs. + +**4.15 Optical Network Termination (ONT):** An ONU used for FTTH and includes the User Port function. + +**4.16 Optical Network Unit (ONU):** An ONU provides (directly or remotely) the user-side interface of the OAN, and is connected to the ODN. As far as the protection functions are concerned, ONU and ONT share the same functionality. Thus, only ONU is referenced in this Recommendation for the sake of clarity. + +**4.17 ranging:** It is necessary to transmit an upstream cell without cell collision in this system. Ranging is a function to measure the logical distance between each ONU and OLT and decide the transmission timing when each ONU receives a grant. + +**4.18 revertive:** A protection configuration is revertive if the system automatically switches back to the working equipment after it is repaired or recovered from a failure condition. Therefore, in a revertive protection configuration, the system has fixed working equipment. The protection equipment is used only when the working equipment is out of service. + +**4.19 service port function:** The Service Port Function (SPF) adapts the requirements defined for a specific SNI to the common bearers handling and selects the relevant information for treatment in the AN system management function. + +**4.20 Time Division Multiple Access (TDMA):** Transmission technique involving the multiplexing of many time slots onto the same time payload. + +**4.21 user port function:** The User Port Function (UPF) adapts the specific UNI requirements to the core and management functions. The AN may support a number of different access and user network interfaces which require specific functions according to the relevant interface specification and the access bearer capability requirements, i.e. bearers for information transfer and protocols. + +**4.22 verification:** It is possible for a malicious user to masquerade as another ONU and use the network if the user knows that the ONU is powered-off. Verification is a function to check whether the connected ONU is masqueraded by a malicious user. + +**4.23 Wavelength Division Multiplexing (WDM):** Bidirectional multiplexing using different optical wavelength for up and downstream signals. + +# **5 Architecture and requirements for a protected optical access network** + +## **5.1 Architecture and requirements** + +### **5.1.1 Service categories** + +The following service categories have been considered: + +- Asymmetric broadband services (e.g. digital broadcast services, VoD, Internet, distance learning, telemedicine, etc.). +- Symmetric broadband services (e.g. telecommunication services for small business customers, teleconsulting, etc.). +- PSTN and ISDN. The access network must be able to provide in a flexible way narrow-band telephone services. +- Reliable services. The access network must be able to provide protection for user traffic that demands high levels of reliability against equipment or facility failures in the network. + +### **5.1.2 Background and requirements** + +Network configuration is basically satisfied with the type B and type C configurations described in ITU-T Rec. G.983.1. The following items are required for the B-PON survivability architecture: + +- Type B protection configuration. In this configuration type (shown in Figure 1), no equipment redundancy is provided in the ONUs. The protection-capable OLT performs switching if its working PON interface fails or its directly connected fibre breaks. G.983.1 compliant ONUs satisfy type B protection configuration without modification. + +- Type C protection configuration. In this configuration type (shown in Figures 2 and 3), equipment redundancy is provided in both the OLT and ONUs. The protection-capable OLT performs switching if any PON interface in the OLT or ONUs fails or if any fibre in the ODN breaks. This Recommendation addresses the modifications to ITU-T Rec. G.983.1 necessary to support the type C protection configuration. +- Mixture of protected and unprotected ONUs in type C configuration. The protection functions shall allow a mixture of protected and unprotected ONUs. In certain fault scenarios, the unprotected ONUs may suffer service disruption while the protected ONUs are recovered. +- X:N variant of type C protection configuration. In this variant of configuration type C (shown in Figure 3), equipment redundancy is provided in the OLT (some or all of the Line Terminals (LTs)) and some or all ONUs. This variant allows protected ONUs to be connected to any of the protection LTs, independent of which working LT they belong to. This variant is optional. +- Extra traffic for type C configuration. Extra traffic should be able to be carried over the protection entities while the working entity is active. The extra traffic will not be protected. This option provides effective usage of bandwidth in the protection entities. It must be possible for an operator not to activate this extra traffic option. + +![Figure 1/G.983.5 – Type B: OLT-only protected system. The diagram shows two ONUs on the left, each containing a PON LT. These ONUs are connected to a central N:2 splitter. The output of the splitter is connected to an OLT on the right. The OLT contains two PON LTs, labeled PON LT(1) and PON LT(0). The diagram is labeled T1550640-02.](007b053fe94a8348f75128a584503fd0_img.jpg) + +Figure 1/G.983.5 – Type B: OLT-only protected system. The diagram shows two ONUs on the left, each containing a PON LT. These ONUs are connected to a central N:2 splitter. The output of the splitter is connected to an OLT on the right. The OLT contains two PON LTs, labeled PON LT(1) and PON LT(0). The diagram is labeled T1550640-02. + +**Figure 1/G.983.5 – Type B: OLT-only protected system** + +![Figure 2/G.983.5 – Type C: Fully protected system, 1:1 and 1+1. The diagram shows two ONUs, ONU #1 and ONU #N, on the left. Each ONU contains two PON LTs, labeled PON LT(1) and PON LT(0). These ONUs are connected to a central 'Double N:1 optical splitter'. The output of the splitter is connected to an OLT on the right. The OLT contains two PON LTs, labeled PON LT(1) and PON LT(0). The diagram is labeled T1550650-02.](27b06ec9f42b5d727a2630f61a5f1861_img.jpg) + +Figure 2/G.983.5 – Type C: Fully protected system, 1:1 and 1+1. The diagram shows two ONUs, ONU #1 and ONU #N, on the left. Each ONU contains two PON LTs, labeled PON LT(1) and PON LT(0). These ONUs are connected to a central 'Double N:1 optical splitter'. The output of the splitter is connected to an OLT on the right. The OLT contains two PON LTs, labeled PON LT(1) and PON LT(0). The diagram is labeled T1550650-02. + +**Figure 2/G.983.5 – Type C: Fully protected system, 1:1 and 1+1** + +![Diagram of Figure 3/G.983.5 – Type C: X:N protection system. The diagram shows an OLT on the right with multiple PON LT interfaces. On the left, there are several ONUs (ONU-1,1, ONU-1,2, ONU-1,3, ONU-1,M_W1, ONU-N,1, ONU-N,2, ONU-N,M_WN). These ONUs are connected to three splitters: M_P1 (1 splitter), M_PX (1 splitter), and M_WN (1 splitter). The splitters are then connected to the OLT. The ONUs are of two types: some have two PON LT interfaces (PON LT (1) and PON LT (0)), while others have one (PON LT). The connections are as follows: ONU-1,1 (PON LT (1)) connects to M_P1; ONU-1,2 (PON LT) connects to M_PX; ONU-1,3 (PON LT (1) and PON LT (0)) connects to M_PX; ONU-1,M_W1 (PON LT (1) and PON LT (0)) connects to M_WN; ONU-N,1 (PON LT (1) and PON LT (0)) connects to M_WN; ONU-N,2 (PON LT) connects to M_WN; ONU-N,M_WN (PON LT (1) and PON LT (0)) connects to M_WN. The OLT has interfaces labeled PON LT(1)-1, PON LT(1)-2, PON LT(1)-X, PON LT(0)-1, PON LT(0)-2, PON LT(0)-3, and PON LT(0)-N. A label T1550660-02 is present at the bottom right of the diagram.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Diagram of Figure 3/G.983.5 – Type C: X:N protection system. The diagram shows an OLT on the right with multiple PON LT interfaces. On the left, there are several ONUs (ONU-1,1, ONU-1,2, ONU-1,3, ONU-1,M\_W1, ONU-N,1, ONU-N,2, ONU-N,M\_WN). These ONUs are connected to three splitters: M\_P1 (1 splitter), M\_PX (1 splitter), and M\_WN (1 splitter). The splitters are then connected to the OLT. The ONUs are of two types: some have two PON LT interfaces (PON LT (1) and PON LT (0)), while others have one (PON LT). The connections are as follows: ONU-1,1 (PON LT (1)) connects to M\_P1; ONU-1,2 (PON LT) connects to M\_PX; ONU-1,3 (PON LT (1) and PON LT (0)) connects to M\_PX; ONU-1,M\_W1 (PON LT (1) and PON LT (0)) connects to M\_WN; ONU-N,1 (PON LT (1) and PON LT (0)) connects to M\_WN; ONU-N,2 (PON LT) connects to M\_WN; ONU-N,M\_WN (PON LT (1) and PON LT (0)) connects to M\_WN. The OLT has interfaces labeled PON LT(1)-1, PON LT(1)-2, PON LT(1)-X, PON LT(0)-1, PON LT(0)-2, PON LT(0)-3, and PON LT(0)-N. A label T1550660-02 is present at the bottom right of the diagram. + +**Figure 3/G.983.5 – Type C: X:N protection system** + +A redundant B-PON system shall satisfy the following requirements: + +- It should be possible to have both the type B and type C protection configurations on the same OLT: + - It should be possible to duplicate the OLT-PON-Interface and the fibres between the OLT and splitter and to duplicate the entire fibre path between the OLT and ONU for a set of ONUs. + - The two configurations should be available on the same OLT, but not on the same ODN interface. +- It should be possible to have multi-vendor interoperability between OLT and ONU. +- In the type C configuration, it should be possible to have a mixture of protected and unprotected ONUs on one B-PON interface. +- The addition or removal of a protected ONU on a PON should not affect other ONUs on the same PON. +- It should be possible to have automatic switching, which would be triggered by a fault detection such as loss of signal, loss of cell delineation, signal degrade (e.g. BER becomes worse than the pre-determined threshold), etc. +- It should be possible to have forced switching, which would be activated by administrative events such as fiber rerouting, fiber replacement, etc. +- It is necessary to avoid unnecessary switching. Because unstable switching affects service quality, unnecessary protection switching and unnecessary revertive protection switching should not occur. +- It should be possible to realise switching without connection loss of the ATM connections. + +- It should be possible for the operator to choose between a revertive and a non-revertive switching mode. +- The service halt time should be less than 50 ms if the extra traffic option is not used. +- The events or conditions that trigger automatic switching should be chosen among the G.983.1 OAM parameters. +- The chosen protocols and mechanisms must apply to the B-PON section layer. +- The type C configuration should be able to support extra traffic: + - Extra traffic should be carried over the protection entities while the working entity is active and would not be protected. This capability will provide effective usage of bandwidth on the protection entities. + - This requirement is applicable only for the type C configuration. + - It must be possible for an operator not to activate the extra traffic option (e.g. to achieve a lower service interruption time). + +## 5.2 Reference configuration + +The reference configuration is the same as shown in Figure 2/G.983.1. + +## 5.3 Functional blocks + +Functional blocks are the same as described in 5.3/G.983.1. + +## 5.4 ONU functional block + +An example of a protected ONT (ONU with User Port Function) is shown in Figure 4. The ONT is active and decouples the access network delivery mechanism from the in-house distribution. The ONT core consists of redundant ODN interfaces, ODN interface switch, User Port, Transmission, Services and Customers Multiplexing (MUX)/demultiplexing functions and powering. + +![Figure 4/G.983.5 – ONU Functional Blocks diagram. The diagram shows the internal architecture of an ONU, divided into three main shells: Service shell, Core shell, and Common shell. The Service shell contains two 'User port Function' blocks, one at the top and one at the bottom, with three asterisks between them. The Core shell contains a 'Customer and services multiplex/demultiplex function' block, a 'Transmission multiplex/demult. function' block, an 'ODN interface switch' block, and two 'ODN interface function' blocks labeled (0) and (1). The Common shell contains 'Power' and 'OAM' blocks. The entire structure is connected to 'Customer' on the left and 'ODN' on the right, with four asterisks between the ODN interface functions and the ODN label. A small code 'T1550670-02' is visible at the bottom right of the diagram.](16c1175b5f05a4b55e6d396fc51b15b3_img.jpg) + +Figure 4/G.983.5 – ONU Functional Blocks diagram. The diagram shows the internal architecture of an ONU, divided into three main shells: Service shell, Core shell, and Common shell. The Service shell contains two 'User port Function' blocks, one at the top and one at the bottom, with three asterisks between them. The Core shell contains a 'Customer and services multiplex/demultiplex function' block, a 'Transmission multiplex/demult. function' block, an 'ODN interface switch' block, and two 'ODN interface function' blocks labeled (0) and (1). The Common shell contains 'Power' and 'OAM' blocks. The entire structure is connected to 'Customer' on the left and 'ODN' on the right, with four asterisks between the ODN interface functions and the ODN label. A small code 'T1550670-02' is visible at the bottom right of the diagram. + +Figure 4/G.983.5 – ONU Functional Blocks + +### 5.4.1 Optical Distribution Network (ODN) interface + +The ODN interface handles the opto-electronic conversion process. The ODN interface extracts ATM cells from the downstream PON payload and inserts ATM cells into the upstream PON payload based on synchronisation acquired from the downstream frame timing. There are two ODN interfaces in a protected ONT/ONU. + +### **5.4.2 Multiplexing** + +The Multiplexer (MUX) multiplexes service interfaces to the ODN interface. Only valid ATM cells can be passed through the MUX, so many VPs can share the assigned upstream bandwidth effectively. + +### **5.4.3 User Port** + +The User Port interfaces over the UNI to a user terminal. The User Port handles functions such as inserting ATM cells into the upstream payload and extracting ATM cells from the downstream payload. + +### **5.4.4 ONU Powering** + +ONU powering may be implementation dependent. + +### **5.4.5 ODN interface switch** + +The ODN interface switch selects the 'in-service' ODN interface. + +## **5.5 OLT functional block** + +The OLT is connected to the switched networks via standardized interfaces (VB5.x, V5.x, NNIs). At the distribution side, it presents optical access according to agreed requirements, in terms of bit rate, power budget, etc. + +![Two functional block diagrams for OLT. The top diagram is labeled 'Core shell' and 'Service shell', showing internal functions like ODN Interface, Transmission MUX/DEMUX, ATM Cross connect, Power, and OAM, with external connections to Core Network and Local exchange. The bottom diagram is labeled 'Core' and 'Service', showing similar internal functions but with a 'Local' connection instead of 'Local exchange'. Both diagrams include a list of external connections: *, * Core Network, *, V5.x/VB Interface, and Local exchange/Local.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +The diagram illustrates the functional blocks of an OLT, divided into two versions: one with 'shells' and one without. + +**Top Diagram: Core shell / Service shell** + +- Core shell:** + - ODN Interface Function(0) + - ODN Interface Function(1) + - Three asterisks (\*) + - ODN Interface Function(0) + - ODN Interface Function(1) + - Transmission MUX/DEMUX B-PON section switch + - ATM Cross connect Function + - Power + - OAM +- Service shell:** + - Service Port Function + - Three asterisks (\*) + - Service Port Function +- External Connections (Right Side):** + - \* + - \* Core Network + - \* + - V5.x/VB Interface + - Local exchange + +**Bottom Diagram: Core / Service** + +- Core:** + - ODN Interface Function(0) + - ODN Interface Function(1) + - Three asterisks (\*) + - ODN Interface Function(0) + - ODN Interface Function(1) + - Transmission MUX/DEMUX B-PON section switch + - ATM Cross connect Function + - Power + - OAM +- Service:** + - Service Port Function + - Three asterisks (\*) + - Service Port Function +- External Connections (Right Side):** + - \* + - \* Core Network + - \* + - V5.x/VB Interface + - Local + +T1550680-02 + +Two functional block diagrams for OLT. The top diagram is labeled 'Core shell' and 'Service shell', showing internal functions like ODN Interface, Transmission MUX/DEMUX, ATM Cross connect, Power, and OAM, with external connections to Core Network and Local exchange. The bottom diagram is labeled 'Core' and 'Service', showing similar internal functions but with a 'Local' connection instead of 'Local exchange'. Both diagrams include a list of external connections: \*, \* Core Network, \*, V5.x/VB Interface, and Local exchange/Local. + +Figure 5/G.983.5 – OLT Functional Blocks + +The OLT consists of three parts: the Service Port function, ODN interface and Transmission MUX/DEMUX/B-PON section switch for VP grooming (see Figure 5). (This combination is not intended to preclude the Virtual Channel (VC) layer function in the OLT. As discussed in ITU-T Rec. G.983.1, this function is for further study.) + +### 1) *Service Port function* + +Same as in item 1) of 5.5/G.983.1. + +### 2) *The Transmission MUX/DEMUX/B-PON section switch* + +This provides VP connections between the Service Port function and the ODN interface and different VPs are assigned to different services at the IFPON. Various information flows such as the main data content, signalling, and OAM cells are exchanged by using VCs of the VP. The transmission MUX/DEMUX/B-PON section switch selects each B-PON section from the redundant ODN interfaces. + +### 3) *ODN interface* + +The PON Line Terminal (LT) handles the opto-electronic conversion process. The ODN interface handles such functions as inserting ATM cells into the downstream PON payload and extracting ATM cells from the upstream PON payload. The ODN interface is redundant. + +## 5.6 Optical Distribution Network (ODN) functional block + +The ODN functional block is the same as in 5.6/G.983.1. + +### 5.6.1 Passive optical elements + +Passive optical elements are the same as in 5.6.1/G.983.1. + +### 5.6.2 Optical interfaces + +In the context of the reference configuration, Figure 6 shows the generic physical configuration of an ODN. + +The two directions for optical transmission in the ODN are identified as follows: + +- downstream direction for signals travelling from the OLT to the ONU(s); +- upstream direction for signals travelling from the ONU(s) to the OLT. + +Transmission in downstream and upstream directions can take place on the same fibre and components (duplex/diplex working) or on separate fibres and components (simplex working). + +If additional connectors or other passive devices are needed for ODN rearrangement, they shall be located between S and R and their losses shall be taken into account in any optical loss calculation. + +The ODN offers one or more optical path between one OLT and one or more ONUs. Each optical path is defined between reference points in a specific wavelength window. + +The following optical interfaces are defined in Figure 6: + +Oru, Ord: optical interface at the reference point R/S between the ONU and the ODN for the upstream and downstream directions, respectively. + +Olu, Old: optical interfaces at the reference point S/R between the OLT and the ODN for the upstream and downstream directions, respectively. + +At the physical layer, the interfaces will require at least two fibres for protected ONUs and OLTs, and may require more than two fibres, e.g. for separation of transmission directions or different types of signals/services. + +Specification of the optical interfaces (Oru, Ord, Olu, Old) are defined in clause 8. + +![Figure 6/G.983.5 – Generic physical configuration of the Optical Distribution Network. The diagram shows an Optical Distribution Network (ODN) block connected to an Optical Line Terminal (OLT) on the right and multiple Optical Network Units (ONUs) on the left. The ONUs are labeled ONU1(0), ONU1(1), and ONU_n. Reference points R/S are indicated at the top of the ONU and OLT connections. Optical interfaces are labeled Ord, Oru at the ONUs and Old, Olu at the OLT. The OLT has a label T1550690-02. A legend below the diagram defines the symbols: R and S are reference points; Ord, Oru, Old, Olu are optical interfaces; bold solid lines represent one or more fibres; dashed lines represent optional protection fibres.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +R and S: Reference points + Ord, Oru, Old, Olu : Optical interfaces + Bold solid lines represent one or more fibres + Dashed lines represent optional protection fibres + +Figure 6/G.983.5 – Generic physical configuration of the Optical Distribution Network. The diagram shows an Optical Distribution Network (ODN) block connected to an Optical Line Terminal (OLT) on the right and multiple Optical Network Units (ONUs) on the left. The ONUs are labeled ONU1(0), ONU1(1), and ONU\_n. Reference points R/S are indicated at the top of the ONU and OLT connections. Optical interfaces are labeled Ord, Oru at the ONUs and Old, Olu at the OLT. The OLT has a label T1550690-02. A legend below the diagram defines the symbols: R and S are reference points; Ord, Oru, Old, Olu are optical interfaces; bold solid lines represent one or more fibres; dashed lines represent optional protection fibres. + +**Figure 6/G.983.5 – Generic physical configuration of the Optical Distribution Network** + +The optical properties of the ODN shall enable the provision of any presently foreseeable service, without the need of extensive modifications to the ODN itself. This requirement has an impact on the properties of the passive optical components which constitute the ODN. A set of essential requirements, which have a direct influence on the optical properties of the ODN, are identified as follows: + +- optical wavelength transparency: devices, such as optical branching devices, which are not intended to perform any wavelength-selective function, shall be able to support transmission of signals at any wavelength in the 1310 nm and 1550 nm regions; +- reciprocity: reversal of input and output ports shall not cause significant changes of the optical loss through the devices; +- fibre compatibility: all optical components shall be compatible with single-mode fibre as specified in ITU-T Rec. G.652. + +For the type B ODN configuration, the optical interface for the active/working OLT interface ( $O_{ld}$ ) is the same as specified in ITU-T Rec. G.983.1. The $O_{ld}$ interface for the inactive/stand-by OLT LT should not be "alight" (i.e. the laser diode should not be active) in order to prevent downstream interference. + +For the type C ODN configuration, the optical interfaces at the OLT and ONU are the same as specified in ITU-T Rec. G.983.1. + +#### 5.6.2.1 Optical Distribution Network model loss calculations + +This is described in ITU-T Rec. G.982. + +#### 5.6.2.2 Optical Distribution Network model loss calculation technique + +This is described in ITU-T Rec. G.982. + +# **6 Services** + +Broadband access networks with protection functions can convey highly reliable services such as leased line or highly reliable VPN. These networks can also transmit the broadband services defined as G.983.1 and/or a mix of protected and unprotected services. In addition, these networks can transmit economical and lower reliability services as so called "extra traffic", which is pre-empted by highly reliable service when some failure occurs. + +# **7 User Network Interface and Service Node Interface** + +The UNI and SNI are the same as in clause 7/G.983.1. + +# **8 Optical network survivability requirements** + +## **8.1 Layer structure of the B-PON survivability optical network** + +The layer structure of the optical network and the physical medium dependent layer requirements are the same as in 8.1 and 8.2/G.983.1. + +### **Layer architecture of type C switching** + +In this clause, the layer architecture of B-PON protection is described. In order to protect each branch line and accommodate mixed protected and unprotected ONUs, survivability for the B-PON system is executed by switching each ONU's traffic. Figure 7 shows the layer architecture of B-PON protection, which is based on the ITU-T Rec. G.805 description. Figure 8 shows the multiplexing structure of the section/path layers between the OLT and ONU with the protection function. + +A B-PON section is defined as the VP group between the OLT and an ONU. If "n" ONUs are connected to an OLT, then there are "n" B-PON sections. These sections are supervised using PLOAM cells as the TC layer function. + +The B-PON section layer protection function is not on the ATM layer, but it is established in the TC layer between one ONU and OLT section including all VPI paths in the ONU, and is executed independently for each branch line failure. To do this, the B-PON section can be checked using the TC layer OAM function. This B-PON section-layer protection leads to higher reliability and flexibility in the ODN protection switching network. + +![Diagram of the layer architecture example in B-PON showing ONTs, ODN, and OLT components and their interactions.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +The diagram illustrates the layer architecture for B-PON, showing the flow of traffic from multiple ONTs through an ODN to an OLT. The components are organized into three main sections: ONTs (ONT#1, ONT#2, ..., ONT#n), ODN (Optical Distribution Network), and OLT (Optical Line Terminal). + +- ONT#1 and ONT#2:** Each ONT has two input traffic types: "Normal traffic" and "Extra traffic". Each traffic type passes through a "VP" (Virtual Path) block, then a "PONP/VP" block, then a "PONP" block. These are followed by a "PONP/PONS" block, a "PONS" block, a "PONS/PON-PHY" block, and finally a "PON-PHY" block. The outputs of these blocks from both traffic types are combined and sent into the ODN. +- ONT#n:** This ONT has only "Normal traffic" which passes through a "VP" block, then a "PONP/VP" block, and finally a "PONS/PON-PHY" block followed by a "PON-PHY" block before entering the ODN. +- ODN:** The Optical Distribution Network is represented by a central vertical line connecting all ONTs to the OLT. +- OLT:** The OLT contains multiple sections labeled #1, #2, through #n. Each section is connected to the ODN via a "PON-PHY/PONS" block and has two output traffic types: "Normal traffic" and "Extra traffic". Each output traffic type passes through a "PONP" block, then a "PONP/VP" block, and finally a "VP" block. + +T1550700-02 + +Diagram of the layer architecture example in B-PON showing ONTs, ODN, and OLT components and their interactions. + +PONS   Passive Optical Network Section + PONP   Passive Optical Network Protection + PON-PHY   Passive Optical Network Physical + VP   Virtual Path + +**Figure 7/G.983.5 – The layer architecture example in B-PON** + +![Diagram illustrating the layer image in B-PON, showing the hierarchy of layers between ONT, ODN, and OLT components.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +The diagram illustrates the layer architecture for B-PON across three main components: ONT (Optical Network Terminal), ODN (Optical Distribution Network), and OLT (Optical Line Terminal). The layers are stacked vertically and horizontally to show their relationships. + +- ONT (Optical Network Terminal):** Contains the following layers from left to right: + - PON Protection Sub-layer + - Bridge/Selector + - PON physical layer +- ODN (Optical Distribution Network):** Represented by a central green vertical block, containing: + - PON section + - VP (Virtual Path) + - VC (Virtual Circuit) +- OLT (Optical Line Terminal):** Contains the following layers from left to right: + - PON physical layer + - PON section + - VP + - VC + - Bridge/Selector + +Below the main diagram, four horizontal double-headed arrows indicate the scope of different layers: + +- PON physical layer:** Spans only the ONT and ODN. +- PON section layer:** Spans only the ODN. +- PON Protection section layer:** Spans the ONT, ODN, and OLT. +- Virtual path layer:** Spans the entire system from ONT to OLT. + +The diagram is labeled with 'T1550710-02' in the bottom right corner. + +Diagram illustrating the layer image in B-PON, showing the hierarchy of layers between ONT, ODN, and OLT components. + +Figure 8/G.983.5 – The layer image in B-PON + +## 8.2 Physical medium dependent layer requirements for B-PON + +Same as ITU-T Rec. G.983.1. + +## 8.3 Additional TC-layer requirements for B-PON survivability + +For physical medium dependent layer requirements, reference is made to ITU-T Recs. G.983.1 and G.983.3. In addition to the TC layer functions already specified in ITU-T Rec. G.983.1, the following TC layer functions are added for the survivability application. + +### 8.3.1 Duplex PON link identification + +In the case of a protected system where a redundant PON protects the active PON, protection switching will be activated using specified messages in PLOAM cells or specific PON protocols. This sequence requires that the line numbers of the OLT must exactly match those of the ONU. The line identifier is assigned to a transmitter based on the interconnection scheme between the OLTs and ONUs. The line identifier is periodically sent to both the OLT and ONU to check whether the received line identifier is the same as the equipment's own identifier. This is defined in the PON Section Trace (PST) message. Each piece of equipment can then verify its continued connection to the intended transmitter. If the received line number differs from the equipment's line number, the equipment generates an alarm, MIS (Link Mismatching). In case of an unprotected system, link mismatching is optional. + +### 8.3.2 Additional messages in the PLOAM channel for survivability + +PLOAM messages are described in 8.3.8.1/G.983.1. For B-PON survivability, the PST message is redefined to include an additional PLOAM message for survivability. This PST message is shown in Table 1. + +**Table 1/G.983.5 – PST Message definition** + +| | Message Name | Function | Direction | Trigger | Number of times sent | Effect of receipt | +|----|--------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------|-----------|--------------------------------------------------------------------------------------|---------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------| +| 15 | PST message
(Broadcast Message)

(If OLT needs to send the same message to all ONUs, it can send this message.) | To check the OLT-ONU connectivity in a redundant configuration and to perform APS. Priority level is 1. | OLT → ONU | Send it when common message for all ONUs should be sent simultaneously. | Same as the individual trigger condition. | Same as the individual message.
(See Note) | +| | PST message
(Individual Message) | To perform APS. Priority level is 1. | | Send it at a certain rate or when OLT detects the APS trigger to change K1/K2 bytes. | 1 time/sec or when K1/K2 bytes should be changed. | ONU checks K1/K2 bytes and performs APS.
(See Note) | +| 28 | PST message | To check the OLT-ONU connectivity in a redundant configuration and to perform APS. Priority level is 1. | OLT ← ONU | Send it a certain rate or when ONU detects the APS trigger to change K1/K2 bytes. | 1 time/sec or when K1/K2 bytes should be changed. | OLT checks link number with own link number and generates a Link Mismatch (MIS) if different

or

OLT checks K1/K2 bytes and performs APS. | + +NOTE – ONU checks link number with own link number and generates a Link Mismatch (MIS) if different. This is checked by sending either individual or broadcast messages. + +### 8.3.3 Message formats + +This clause defines the contents of the messages described in the previous section. + +#### 8.3.3.1 Downstream message formats + +Downstream message formats shall be referenced to ITU-T Rec. G.983.1. The PST message shown in Table 2 is added for the survivability application. + +**Table 2/G.983.5 – Downstream message formats** + +| PST message | | | +|-------------|--------------------|----------------------------------------------------------------| +| Octet | Content | Description | +| 35 | 01000000 or PON_ID | Broadcast message to all ONUs or individual message to one ONU | +| 36 | 10000000 | Message identification "PST" | +| 37 | Linenumber | Can be 0 or line identifier | +| 38 | Control | This is the K1 byte as specified in ITU-T Rec. G.783 | +| 39 | Control | This is the K2 byte as specified in ITU-T Rec. G.783 | +| 40..46 | Unspecified | | + +#### 8.3.3.2 Upstream message formats + +Upstream message formats shall be referenced to ITU-T Rec. G.983.1. The PST message shown in Table 3 is added for the survivability application. + +**Table 3/G.983.5 – Upstream message formats** + +| PST message | | | +|-------------|-------------|------------------------------------------------------| +| Octet | Content | Description | +| 2 | PON_ID | Indicates the ONU sourcing this message | +| 3 | 10000010 | Message identification "PST" | +| 4 | Linenumber | Can be 0 or line identifier | +| 5 | Control | This is the K1 byte as specified in ITU-T Rec. G.783 | +| 6 | Control | This is the K2 byte as specified in ITU-T Rec. G.783 | +| 7..13 | Unspecified | | + +## 8.4 Ranging Method + +Same as ITU-T Rec. G.983.1. + +## 8.5 Protection switching + +### 8.5.1 PON Protection function + +#### Type B switching architecture + +No specific requirements for type B configuration ONUs are foreseen. + +For the OLT, two new functions are required: a select function to choose the PON-IF and a shut-down function for the stand-by PON-IF. + +#### Type C switching architecture + +For type C configuration, the B-PON section protection is required. One B-PON section corresponds to one connection between an OLT and an ONU, and may contain several TCONTs and VPI paths. B-PON section protection is executed independently by each branch line failure. This permits mixed connection of protected and unprotected ONUs and leads to higher reliability and flexibility in the ODN switching network. + +##### 1:1 and 1+1 architecture + +There are two types of protection architecture: + +##### i) *1:1 architecture* + +In the source direction, the working entity conveys the traffic in the normal case. If the working entity fails or a forced/manual switch is executed, the protection entity conveys the traffic. + +##### ii) *1+1 architecture* + +In the source direction, the signal is bridged to both the working and protection entities. In the sink direction, one source signal (which must have good transmission quality) is selected. + +NOTE – Only the 1:1 architecture can support extra traffic. + +Figures 9 and 10 show the 1:1 and 1+1 switching architecture, respectively. + +##### X:N architecture + +In this scheme, X protection PONs are provided for N working PONs (with X between 1 and N). The N working PONs can have a mixture of protected and unprotected ONUs. The protected ONUs can be connected to any of the X protection PONs, so that protected ONUs belonging to the same working PON can be connected to different protection PONs and protected ONUs belonging to different working PONs can be connected to the same protection PON. + +This scheme is compatible with both the 1:1 and 1+1 switching implementations and is independent of protocol. It provides protection against multiple failures in different working PONs with less than N protection PONs. + +![Diagram of 1:1 switching architecture showing Downstream and Upstream traffic paths between an ONT and an OLT.](a3953dce8dbd7ef15d61a314dbef2cf9_img.jpg) + +The diagram illustrates the 1:1 switching architecture between an Optical Network Terminal (ONT) and an Optical Line Terminal (OLT). It is divided into two main sections: Downstream (top) and Upstream (bottom). + +**Downstream:** Shows traffic flow from the OLT to the ONT. The OLT has two output paths: a solid line labeled 'working' and a dashed line labeled 'protection'. Both paths connect to a switching mechanism inside the ONT. The ONT has two output ports: 'Normal' and 'Extra'. The 'Normal' port is connected to the working path, and the 'Extra' port is connected to the protection path. A 'copy' label is present in the ONT's switching area. The OLT also has a 'copy' label in its switching area. + +**Upstream:** Shows traffic flow from the ONT to the OLT. The ONT has two input paths: a solid line labeled 'working' and a dashed line labeled 'protection'. Both paths connect to a switching mechanism inside the OLT. The OLT has two output ports: 'Normal' and 'Extra'. The 'Normal' port is connected to the working path, and the 'Extra' port is connected to the protection path. A 'copy' label is present in the OLT's switching area. The ONT also has a 'copy' label in its switching area. + +A 'PST message (K1K2)' is shown as a control signal between the ONT and the OLT. + +The diagram is labeled 'Figure 9/G.983.5 – 1:1 switching architecture' and includes the code 'T1550720-02'. + +Diagram of 1:1 switching architecture showing Downstream and Upstream traffic paths between an ONT and an OLT. + +Figure 9/G.983.5 – 1:1 switching architecture + +![Figure 10/G.983.5 – 1+1 switching architecture diagram showing Downstream and Upstream paths between an ONT and an OLT with working and protection channels.](7133ccf78043568ca62ecbcd43628a4a_img.jpg) + +The diagram illustrates the 1+1 switching architecture for Downstream and Upstream traffic between an Optical Network Terminal (ONT) and an Optical Line Terminal (OLT). + +- Downstream Path:** On the left, an ONT box contains a switch mechanism. Two arrows point from the ONT towards the right, labeled "working" and "protection". These arrows enter a central box representing the network. On the right, an OLT box contains a "copy" block that receives both working and protection signals. An arrow points out from the OLT to the right. +- Upstream Path:** On the left, an ONT box contains a "copy" block that receives signals from the left. Two arrows point from this copy block towards the right, labeled "working" and "protection". These arrows enter the central network box. On the right, an OLT box contains a switch mechanism that selects between the working and protection signals. An arrow points out from the OLT to the right. +- Control Signal:** A line labeled "SF/SD + PST message (K1K2)" connects the OLT back to the ONT in the upstream path. +- Labels:** The diagram is labeled "Downstream" at the top left and "Upstream" at the bottom left. The components are labeled "ONT", "OLT", "working", "protection", and "copy". A small code "T1550730-02" is at the bottom right. + +Figure 10/G.983.5 – 1+1 switching architecture diagram showing Downstream and Upstream paths between an ONT and an OLT with working and protection channels. + +**Figure 10/G.983.5 – 1+1 switching architecture** + +### 8.5.2 Protocols + +To satisfy the requirements described in 5.1.2, the fast switching protocol described in Annex A is recommended. + +### 8.5.3 Switching criteria + +Basically, type B switching does not require any communication between the OLT and ONUs, and forced and automatic switching are executed only at the OLT side. The trigger for automatic switching should be the same as for type C. + +Type C switching commands are described as follows. + +#### 1) *Externally initiated commands* + +Externally initiated commands (e.g. forced switch/manual switch operation) are always issued by the OLT side. + +#### 2) *Automatically initiated commands* + +Automatic protection switching is based on the failure conditions of the working and protection B-PON sections. Signal Fail (SF) and Signal Degrade (SD) commands are provided by the OLT and ONU. + +The expected switching triggers (Signal Failure or Signal Degrade) are listed below. + +##### a) *Trigger of SF on the OLT* + +The OLT recognizes an SF condition when it detects the following alarms: + +- LOSi, LCDi, CPEi, OAMLi, SUFi, LOAi, PEEi, DFi, TF, and +- equipment failure or removal of PON LT (0/1). + +##### b) *Trigger of SD on the OLT* + +The OLT recognizes an SD condition when it detects the following alarm: + +- SD. + +##### c) *Trigger of SF on the ONU* + +The ONU recognizes an SF condition when it detects the following alarms: + +- OAML, FRML, LCD, LOS, PEE, DIS, TF, and +- equipment failure or removal of PON LT (0/1). + +##### d) *Trigger of SD on the ONU* + +The ONU recognizes an SD condition when it detects the following alarm: + +- SD. + +Switching triggers detected by the ONU are transferred by the K1 byte in the PST message to the OLT. + +The TC layer alarms are detected on both the working and protection sides. + +### 8.5.4 Performance + +Detection time depends on the frequency at which data/PLOAM cells are transmitted. In particular, SD detection time may be long in lower-speed services. SF detection time should be under 10 ms for data transmission rates greater than 1.5 Mbit/s. + +The definitions of detection time, switching guard time and switching time are shown in Figures 11 and 12. Figure 11 illustrates the relation between switching time and detection time when the optional POPUP procedure is used. (The POPUP procedure is the ranging protocol used when the ONT is in the POPUP state (O10) defined in ITU-T Rec. G.983.1.) These figures indicate that switching may be executed after the POPUP procedure fails to give the system a chance to recover working traffic via the POPUP procedure and, hence, to avoid unnecessary switching. When a system does not use the POPUP procedure, switching guard time may be very short. Figure 12 explains the relation between switching time and detection time when the POPUP procedure is not used. + +When a PON is not carrying extra traffic, the *service\_halt\_time* should be under 50 ms for 32 ONUs, where the *service\_halt\_time* is defined as: + +$$\text{service\_halt\_time} = \text{detection\_time} + \text{switching\_guard\_time} + \text{switching\_time}$$ + +Switching guard time and POPUP guard time are set in practical systems. The priority for reranging and switching is set according to these guard times. + +i) Example of POPUP ranging failure (switching executes) + +![Timing diagram for POPUP ranging failure. It shows two horizontal timelines: LOSi (ON/OFF) and Service (ON/OFF). The LOSi timeline starts with an 'invalid' state, then transitions to OFF at 'detection time'. A 'POPUP guard time' interval is marked. A 'POPUP procedur' box is shown above the timeline, with a 'Ranging failure' label. A 'Switching guard time' interval is marked, leading to a 'Switching' box and 'Switching time'. The Service timeline remains ON throughout.](043e64d41a3368d138ace3816fd26469_img.jpg) + +The diagram illustrates the timing for a POPUP ranging failure. The LOSi signal starts in an 'invalid' state, then transitions to OFF at the 'detection time'. A 'POPUP guard time' interval is indicated. A 'POPUP procedur' box is shown above the timeline, with a 'Ranging failure' label. A 'Switching guard time' interval is marked, leading to a 'Switching' box and 'Switching time'. The Service signal remains ON throughout the process. + +Timing diagram for POPUP ranging failure. It shows two horizontal timelines: LOSi (ON/OFF) and Service (ON/OFF). The LOSi timeline starts with an 'invalid' state, then transitions to OFF at 'detection time'. A 'POPUP guard time' interval is marked. A 'POPUP procedur' box is shown above the timeline, with a 'Ranging failure' label. A 'Switching guard time' interval is marked, leading to a 'Switching' box and 'Switching time'. The Service timeline remains ON throughout. + +ii) Example of POPUP ranging success (switching does not execute) + +![Timing diagram for POPUP ranging success. It shows two horizontal timelines: LOSi (ON/OFF) and Service (ON/OFF). The LOSi timeline starts with an 'invalid' state, then transitions to OFF at 'detection time'. A 'POPUP guard time' interval is marked. A 'POPUP procedur' box is shown above the timeline, with a 'Ranging success' label. The Service timeline remains ON throughout. A reference code T1550740-02 is present.](2ae3eae1bd80a90f192f568ae246a9a6_img.jpg) + +The diagram illustrates the timing for a POPUP ranging success. The LOSi signal starts in an 'invalid' state, then transitions to OFF at the 'detection time'. A 'POPUP guard time' interval is indicated. A 'POPUP procedur' box is shown above the timeline, with a 'Ranging success' label. The Service signal remains ON throughout the process. A reference code T1550740-02 is present. + +Timing diagram for POPUP ranging success. It shows two horizontal timelines: LOSi (ON/OFF) and Service (ON/OFF). The LOSi timeline starts with an 'invalid' state, then transitions to OFF at 'detection time'. A 'POPUP guard time' interval is marked. A 'POPUP procedur' box is shown above the timeline, with a 'Ranging success' label. The Service timeline remains ON throughout. A reference code T1550740-02 is present. + +Figure 11/G.983.5 – Protection switching typical model (With POPUP procedure) + +![Timing diagram for protection switching without POPUP procedure. It shows two horizontal timelines: LOSi (ON/OFF) and Service (ON/OFF). The LOSi timeline starts with an 'invalid' state, then transitions to OFF at 'detection time'. A 'Switching guard time' interval is marked, leading to a 'Switching' box and 'Switching time'. The Service timeline remains ON throughout. A reference code T1550750-02 is present.](4cde160bcc69b7b6c81b648dd0e4252e_img.jpg) + +The diagram illustrates the timing for protection switching without the POPUP procedure. The LOSi signal starts in an 'invalid' state, then transitions to OFF at the 'detection time'. A 'Switching guard time' interval is marked, leading to a 'Switching' box and 'Switching time'. The Service signal remains ON throughout the process. A reference code T1550750-02 is present. + +Timing diagram for protection switching without POPUP procedure. It shows two horizontal timelines: LOSi (ON/OFF) and Service (ON/OFF). The LOSi timeline starts with an 'invalid' state, then transitions to OFF at 'detection time'. A 'Switching guard time' interval is marked, leading to a 'Switching' box and 'Switching time'. The Service timeline remains ON throughout. A reference code T1550750-02 is present. + +Figure 12/G.983.5 – Protection switching typical model (Without POPUP procedure) + +# **9 Operations Administration and Maintenance (OAM) functionality** + +Same as ITU-T Rec. G.983.1. + +# **10 Performance** + +Same as ITU-T Rec. G.983.1. + +# **11 Environmental condition** + +Same as ITU-T Rec. G.983.1. + +# **12 Safety** + +Same as ITU-T Rec. G.983.1. + +# **Annex A** + +## **Fast switching protocol for the B-PON access network** + +This annex describes the survivability architecture for B-PON and the method of using MSP bytes and MSP commands. + +## **A.1 Survivability Architecture** + +### **A.1.1 1:1 architecture (required)** + +The 1:1 architecture is shown in Figure A.1 and this architecture is required. + +In the downstream direction, both normal and extra traffic are broadcast to selectors that choose the type of traffic (normal or extra) that is to be transmitted onto the ODN. In the ONU, there is a simple function that selects the correct traffic flow from the OLT. + +In the upstream direction, the survivability mechanism is essentially the same (as the downstream). Both normal and extra traffic are sent to selectors in the ONU, which routes the appropriate traffic stream to the OLT. In the OLT, a simple selection function chooses the traffic stream. + +For both upstream and downstream, if extra traffic is not supported, the selector at the receiver side may be replaced by a simple merger. + +Each of the selectors must select the opposite signal to the one chosen by the other selector, e.g. if one selector in the OLT selects normal traffic, the other selector must select extra traffic. In the ONU, the same selector choices are required. + +Switching is accomplished in the transmitting end via the selectors, which are set based on PST messages from the OLT. In the event of a failure that affects only downstream traffic, the ONU must notify the OLT of the failure in order to initiate switching. In this case, the ONU will cease to send any cells in response to grants on the working PON. This will cause a LOSi in the OLT and the switching will be initiated. + +Switching between working and protection PONs is only possible if the standby TC layer alarms are not active and the PST message transmission is valid. + +The VPI/VCI values of normal traffic and extra traffic shall be different to perform fast switching. + +![Diagram of 1:1 Architecture showing Downstream and Upstream traffic paths between ONT and OLT. The diagram is split into two horizontal sections: 'Downstream' (top) and 'Upstream' (bottom). In the Downstream section, traffic from the OLT (Normal and Extra) is copied and sent to both the 'working' and 'protection' PONs. The ONT receives both and selects based on signal quality. In the Upstream section, traffic from the ONT (Normal and Extra) is copied and sent to both the 'working' and 'protection' PONs. The OLT receives both and selects based on signal quality. A 'PST message (K1K2)' is shown being sent from the ONT to the OLT. The diagram includes labels for 'Normal', 'Extra', 'copy', 'working', 'protection', 'ONT', and 'OLT'. A small code 'T1550760-02' is in the bottom right.](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg) + +Diagram of 1:1 Architecture showing Downstream and Upstream traffic paths between ONT and OLT. The diagram is split into two horizontal sections: 'Downstream' (top) and 'Upstream' (bottom). In the Downstream section, traffic from the OLT (Normal and Extra) is copied and sent to both the 'working' and 'protection' PONs. The ONT receives both and selects based on signal quality. In the Upstream section, traffic from the ONT (Normal and Extra) is copied and sent to both the 'working' and 'protection' PONs. The OLT receives both and selects based on signal quality. A 'PST message (K1K2)' is shown being sent from the ONT to the OLT. The diagram includes labels for 'Normal', 'Extra', 'copy', 'working', 'protection', 'ONT', and 'OLT'. A small code 'T1550760-02' is in the bottom right. + +**Figure A.1/G.983.5 – 1:1 Architecture** + +### A.1.2 1+1 Architecture (optional) + +The 1+1 Architecture is shown in Figure A.2. This architecture is optional. + +In the downstream direction, the traffic is bridged to both the working and the protection PONs. In the ONU, the traffic is selected based on signal quality and/or PST messaging. + +In the upstream direction the same functionality exists. Traffic is bridged to both working and protection PONs and on the receive side a selection mechanism selects traffic based on signal quality and provisioning. + +Switching is initiated at the receiver that first detects a fault. In the event of a failure that effects only downstream traffic, the ONU must notify the OLT of the failure in order to complete the switching event. In this case, the ONU will cease to send any cells in response to grants on the working PON. This will cause a LOSi in the OLT and the switching action will be completed. + +Extra traffic is not supported in this architecture. + +Switching between working and protection PONs can be executed only if the destination traffic is valid. + +![Diagram of 1+1 Architecture showing Downstream and Upstream paths between ONT and OLT. The Downstream path shows a switch at the ONT selecting between 'working' and 'protection' paths from the OLT, with a 'copy' function at the OLT. The Upstream path shows a 'copy' function at the ONT sending data to both 'working' and 'protection' paths to the OLT, which then switches to the output. A message line labeled 'SF/SD + PST message (K1K2)' connects the ONT and OLT.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg) + +The diagram illustrates the 1+1 architecture for optical transport. It is divided into two horizontal sections: 'Downstream' (top) and 'Upstream' (bottom). + In the 'Downstream' section, an 'ONT' (Optical Network Terminal) on the left has a switch that can select between two input paths from an 'OLT' (Optical Line Terminal) on the right. These paths are labeled 'working' and 'protection'. The OLT has a 'copy' function that duplicates the incoming signal onto both paths. A line labeled 'SF/SD + PST message (K1K2)' connects the ONT and OLT. + In the 'Upstream' section, the ONT on the left has a 'copy' function that duplicates the outgoing signal onto both the 'working' and 'protection' paths to the OLT on the right. The OLT then has a switch that selects one of these two paths for output. + +Diagram of 1+1 Architecture showing Downstream and Upstream paths between ONT and OLT. The Downstream path shows a switch at the ONT selecting between 'working' and 'protection' paths from the OLT, with a 'copy' function at the OLT. The Upstream path shows a 'copy' function at the ONT sending data to both 'working' and 'protection' paths to the OLT, which then switches to the output. A message line labeled 'SF/SD + PST message (K1K2)' connects the ONT and OLT. + +**Figure A.2/G.983.5 – 1+1 Architecture** + +## A.2 MSP bytes + +This switching protocol uses a part of K1/K2 bytes defined in Annex A/G.783 to control the selector and bridge in the ONU. The bit assignments for these bytes and the bit-oriented protocol are defined in the following. + +### A.2.1 K1 byte + +As the OLT is the master of the switching, the OLT uses the following requests in the sent K1: + +Lockout of protection, Forced switching, Signal fail low priority, Signal degrade low priority, Manual switching, Wait to Restore, Do Not revert and No Request. + +In response to requests from the OLT, the ONU uses following requests in the sent K1: + +Reverse request and No request. + +### A.2.2 K1 byte generation rules + +Refer to A.1.2/G.783. + +#### A.2.2.1 In bidirectional operation + +The B-PON system only supports bidirectional operation. + +In the OLT, the local request is sent in the K1 byte. + +In the ONU, two responses shall be sent in response to the OLT request. + +The reverse request shall be sent when the ONU can perform the upstream switch. + +The no request shall be sent when the ONU releases or does not perform the upstream switch. + +### A.2.3 Revertive/non-revertive modes + +Refer to A.1.3/G.783. + +Non-revertive operation is also applicable to the 1:1 architecture. + +### **A.2.4 K2 byte** + +Refer to A.1.4/G.783. + +As the ATM-PON system does not indicate MS-AIS and MS-RDI in bits 6 to 8, these bits can indicate the switching mode (i.e. bidirectional, using code 101). + +### **A.2.5 Control of the upstream switch in the ONU and the downstream switch in the OLT** + +In the OLT, the local request is the switching trigger of the downstream switch. + +In the ONU, the local request or the remote request is the switching trigger of the upstream switch. + +If the protection section is in a SF condition, the switches in the OLT and ONU are released. + +### **A.2.6 Transmission and acceptance of MSP Bytes** + +Refer to A.1.8/G.783. + +As the MSP message is in the PLOAM cell, it is protected by the CRC-8 and hence can be accepted as valid when the CRC-8 detects no error. + +## **A.3 MSP commands** + +There are five switching commands and two control commands in A.2/G.783. + +As the lockout of working channel command cannot be transmitted to the ONU by the MSP bytes, the ONU does not stop switching the upstream switch if the downstream SF or SD is detected even if the lockout of working channel would like to be performed. Therefore the lockout of protection command can be used on behalf of the lockout of working channel command. + +The exercise command is not allowed in order to avoid unnecessary switching. + +As a result, the following commands are specified for B-PON survivability. + +- Clear; +- Lockout of protection; +- Forced switch; +- Manual switch. + +## **A.4 Switching Sequence** + +For PST message transmission, only the PST message from the protection side is used. If the PST message is received with an invalid CRC or both line failure, the OLT and ONU should select the working side. + +### **A.4.1 1:1 bidirectional operation with non-revertive mode** + +When the protection section is not in use, null channel is indicated on both sent K1 and K2 bytes. The working channel should be bridged and switched to the working section at the head section. The null channel is bridged and switched to the protection section at the head end. + +When a failure condition is detected at the ONU, the K1 byte in the protection section informs the OLT of the priority. The bridge and switch action is also performed at the ONU. The K2 byte shows the new bridge status. + +The received K1 byte is compared with the local request at the OLT. The higher priority is chosen as the K1 byte order with the channel number. The bridge and switch action is also performed at the OLT. The K2 byte shows the new bridge status. + +If single failure occurs in the ONU, the switching operation is completed. + +When a failure condition is detected at the OLT, the K1 byte in protection section informs the ONU of the priority. The bridge and switch action is also performed at the OLT. The K2 byte shows the new switching status. + +The received K1 byte is compared with the local request at the ONU. The switching order is performed as the result of the highest priority. The K1 byte from the ONU informs the OLT of the highest priority at the ONU. The K2 byte also shows the switching status at the ONU. + +The OLT confirm the switching status in the ONU with the received K2 byte. If single failure occurs in the OLT, the switching operation is completed. + +If the ONU detects the signal failure, it stops the upstream signal. This is a part of ranging state diagram. This also helps the fast failure notification to the OLT. When the failure is recovered, the OLT and ONU inform the opposite side of the Wait To Restore notification in the K1 byte. After WTR time is expired, the OLT sends the Do not Revert or No Request and the ONU sends Reverse Request or No request depending on the bridge status. If it is the case of non-revertive mode, WTR timer may not be used. In such case, DNR sends after the failure is recovered. + +An example is given in Table A.1. + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|------------------------------------------------------------------|-----------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------------|------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 1
Upstream
SF and
recovery on
working
section | No failure
traffic is on the working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the
working section at OLT. | | 11000001/00011101 | | Bridge and switch the
working channel to the
protection section. | +| | | 00100001/00011101 | | Bridge and switch the
working channel to the
protection section. | | +| | SF is cleared at OLT .
Non revertive mode | | 01100001/00011101 | | | +| | | | 00010001/00011101 | | Wait to restore is expired. | +| | | 00100001/00011101 | | Wait to restore is expired. | | +| No. 2
Upstream
SD and
recovery on
working
section | No failure
traffic is on working
section | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on working
section at OLT | | 10100001/00011101 | | Bridge and switch the
working channel to the
protection section. | +| | | 00100001/00011101 | | Bridge and switch the
working channel to the
protection section. | | +| | SD is cleared.
Non revertive mode | | 01100001/00011101 | | | +| | | | 00010001/00011101 | | Wait to restore is expired. | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------------|----------------------------------------------------|-------------------|-------------------|---------------------------------------------------------------------|---------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 3
Upstream SF
and recovery
on
protection
section | No failure
traffic is on protection
section. | 00100001/00011101 | 00010001/00011101 | | | +| | SF is detected on
protection section at OLT | | 11000000/00001101 | | Bridge and switch the
working channel to the
working section. | +| | | 00100001/00001101 | | Bridge and switch the
working channel to the
working section. | | +| | SF is cleared.
Non revertive mode | | 01100000/00001101 | | | +| | | | 00000000/00001101 | | Wait to restore is expired. | +| | | 00000000/00001101 | | Wait to restore is expired. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------------|----------------------------------------------------|-------------------|-------------------|---------------------------------------------------------------------|---------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 4
Upstream
SD and
recovery on
protection
section | No failure
traffic is on protection
section. | 00100001/00011101 | 00010001/00011101 | | | +| | SD is detected on
protection section at OLT. | | 10100000/00001101 | | Bridge and switch the
working channel to the
working section. | +| | | 00100000/00001101 | | Bridge and switch the
working channel to the
working section. | | +| | SD is cleared. Non
revertive mode | | 01100000/00001101 | | | +| | | | 00000000 00001101 | | Wait to restore is expired. | +| | | 00000000/00001101 | | | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------|--------------------------------------------------|-------------------|-------------------|----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 5
Downstream
SF and
recovery on
working
section | No failure
traffic is on working
section. | 00000000 00001101 | 00000000/00001101 | | | +| | SF is detected on the
working section at ONU. | 11000001/00011101 | | Stop the upstream signal on
working section at ONU.
Bridge and switch the
working channel to the
protection section. | | +| | SF is detected on the
working section at OLT. | | 11000001/00011101 | | Detect LOSi .
Bridge and switch the
working channel to the
protection section. | +| | SF is cleared at OLT and
ONU. | 01100001/00011101 | 01100001/00011101 | Recover the upstream
signal after ranging. | | +| | | | 00010001/00011101 | | Wait to restore is expired. | +| | | 00100001/00011101 | | Wait to restore is expired. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------|--------------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------------|------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 6
Downstream
SD and
recovery on
working
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on the
working section at an
ONU. | 10100001/00011101 | | Bridge and switch the
working channel to the
protection section. | | +| | | | 00100001/00011101 | | Bridge and switch the
working channel to the
protection section. | +| | SD is cleared at ONU. | 01100001/00011101 | | | | +| | | | 00010001/00011101 | | | +| | | 00100001/00011101 | | Wait to restore is expired. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|-----------------------------------------------------------------------|-----------------------------------------------------------|-------------------|-------------------|-------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 7
Downstream
SF and
recovery on
protection
section | No failure
traffic is on protection
section. | 00100001 00011101 | 00010001/00011101 | | | +| | SF is detected on the
protection section at an
ONU. | 11000000/00001101 | | Stop the upstream signal on
the protection section.
Bridge and switch the
working channel to the
working section. | | +| | | | 11000000/00001101 | | Detect LOSi.
Bridge and switch the
working channel to the
working section. | +| | SF is cleared. | 01100000/00001101 | 01100000/00001101 | | | +| | | | 00000000/00001101 | | Wait to restore is expired. | +| | | 00000000/00001101 | | Wait to restore is expired. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|-------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|-------------------|-------------------|---------------------------------------------------------------|---------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 8
Downstream SD and recovery on protection section | No failure traffic is on protection section. | 00100001/00011101 | 00010001/00011101 | | | +| | SD is detected on the protection section at an ONU. | 10100000/00001101 | | Bridge and switch the working channel to the working section. | | +| | | | 00100000/00001101 | | Bridge and switch the working channel to the working section. | +| | SD is cleared at ONU. | 01100000/00001101 | | | | +| | | 00000000/00001101 | | Wait to restore is expired. | | +| | | | 00000000/00001101 | | | +| No. 9
Upstream SF on both working and protection section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the protection section at the OLT.
SF is detected on the working section at the OLT. | | 11000000/00001101 | | Bridge and switch the working channel to the working section. | +| | | 00100000/00001101 | | Bridge and switch the working channel to the working section. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------|------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 10
Upstream SD on both working and protection section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SDs are detected on both working and protection sections at OLT. | | 10100000/00001101 | | Bridge and switch the working channel to the working section. | +| | | 00100000/00001101 | | Bridge and switch the working channel to the working section. | | +| No. 11
Upstream SF on the working section and SD on protection section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the working channel at the OLT. SD is also detected on the protection channel at the OLT. | | 11000001/00011101 | | Bridge and switch the working channel to the protection section. | +| | | 00100001/00011101 | | Bridge and switch the working channel to the protection section. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------|-------------------|-------------------|---------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 12
Downstream
SF on both
working
section and
protection
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the
protection section at the
ONU.
SF is also detected on the
working section at the
ONU. | 11000000/00001101 | | Stop the upstream signal on
both the working and
protection section.
Bridge and switch the
working channel to the
working section. | | +| | | | 11000000/00001101 | | Detect LOSi on both the
working and protection
sections.
Bridge and switch the
working channel to the
working section. | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|-----------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------|-------------------|-------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 13
Downstream
SF on the
working
section and
SD on
protection
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the
working section at the
ONU.
SD is also detected on the
protection section at the
ONU. | 11000001/00011101 | | Stop the upstream signal on
the working section.
Bridge and switch the
working channel to the
protection section. | | +| | | | 11000001/00011101 | | Detect LOSi .
Bridge and switch the
working channel to the
protection section. | +| No. 14
Downstream
SD on both
working and
protection
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SDs are detected on both
working and protection
sections. | 10100000/00001101 | | Bridge and switch the
working channel to the
working section. | | +| | | | 00100000/00001101 | | Bridge and switch the
working channel to the
working section. | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|----------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|-------------------|-------------------|----------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 15
Upstream SF on protection section and Downstream SF on working section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the working section at the ONU.
SF is detected on the protection section at the OLT. | 11000001/00011101 | 11000000/00001101 | Stop the upstream signal on the working section.
Bridge and switch the working channel to the protection section. | Bridge and switch the working channel to the working section. | +| | | 11000001/00001101 | | Bridge and switch the working channel to the working section. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|-----------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------|-------------------|-------------------|-----------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 16
Upstream
SF on
protection
section and
Downstream
SD on
working
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the
protection section at the
OLT.

SD is detected on the
working section at the
ONU. | 10100001/00011101 | 11000000/00001101 | Bridge and switch the
working channel to the
protection section. | Bridge and switch the
working channel to the
working section. | +| | | 11010001/00001101 | | Bridge and switch the
working channel to the
working section. | | +| No. 17
Upstream
SD on
protection
section and
Downstream
SF on the
working
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on the
protection section at the
OLT.

SF is detected on the
working section at the
ONU. | 11000001/00011101 | 10100000/00001101 | Stop the upstream signal on
the working section.

Bridge and switch the
working channel to the
protection section. | Bridge and switch the
working channel to the
working section. | +| | | | 11000001/00011101 | | Detect LOSi on the working
section.

Bridge and switch the
working channel to the
protection section. | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|-------------------|-------------------|----------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 18
Upstream SD on protection section and Downstream SD on the working section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on the protection section at the OLT. SD is detected on the working section at the ONU. | 10100001/00011101 | 10100000/00001101 | Bridge and switch the working channel to the protection section. | Bridge and switch the working channel to the protection section. | +| | | 10100001/00001101 | | Bridge and switch the working channel to the working section. | | +| No. 19
Upstream SF on working section and Downstream SF on protection section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the working section at the OLT.
SF is detected on the protection section at the ONU. | 11000000/00001101 | 11000001/00011101 | Stop the upstream signal on the protection section.
Bridge and switch the working channel to the working section. | Bridge and switch the working channel to the protection section. | +| | SF is detected on the working section at the ONU. | | 11000000/00001101 | | LOSi is detected on the protection section.
Bridge and switch the working channel to the working section. | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------|-------------------|-------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 20
Upstream SD
on working
section and
Downstream
SF on the
protection
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on the
working section at the
OLT.
SF is detected on the
protection section at the
ONU. | 11000000/00001101 | 10100001/00011101 | Stop the upstream signal on
the protection section.
Bridge and switch the
working channel to the
working section. | Bridge and switch the
working channel to the
protection section. | +| | SF is also detected on the
protection section at the
OLT. | | 11000000/00001101 | | Detect LOSi on the
protection section.
Bridge and switch the
working channel to the
working section | +| No. 21
Upstream SF
on working
section and
Downstream
SD on
protection
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the
working section at the
OLT.
SD is detected on the
protection section at the
ONU. | 10100000/00001101 | 11000001/00011101 | Bridge and switch the
working channel to the
working section. | Bridge and switch the
working channel to the
protection section. | +| | | 10100000/00011101 | | Bridge and switch the
working channel to the
protection section. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------|------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 22
Upstream SD
on working section and
Downstream SD on the protection section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on the working section at the OLT.
SD is detected on the protection section at the ONU. | 10100000/00001101 | 10100001/00011101 | Bridge and switch the working channel to the working section. | Bridge and switch the working channel to the protection section. | +| | | | 10100001/00001101 | | Bridge and switch the working channel to the working section. | +| No. 23
Forced switch to protection section | No failure traffic is on working section. | 00000000/00001101 | 00000000/00001101 | | | +| | Forced switch order | | 11100001/00011101 | | Bridge and switch the working channel to the protection section. | +| | | 00100001/00011101 | | Bridge and switch the working channel to the protection section. | | + +**Table A.1/G.983.5 – 1:1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------|--------------------------------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 24
Forced switch to working section | No failure traffic is on protection section. | 00100001/00011101 | 00010001/00011101 | | | +| | Forced switch order | | 11100000/00001101 | | Bridge and switch the working channel to the working section. | +| | | 00100000/00001101 | | Bridge and switch the working channel to the working section. | | +| | | | 00000000/00001101 | | | +| | | 00000000/00001101 | | | | +| No. 25
Manual switch and Downstream SD on working section | No failure traffic is on protection section. | 00100001/00011101 | 00010001/00011101 | | | +| | SD is detected on the working section at the ONU.
Manual Switch order | 10100001/00011101 | 10000000/00001101 | Bridge and switch the working channel to the protection section. | | +| | SD is higher priority than the manual switch. | 10100001/00011101 | 10000000/00001101 | | Bridge and switch the working channel to the protection section after receiving the response from ONU. | +| | The manual switch results in failure. | 10100001/00011101 | 00010001/00011101 | | | + +### **A.4.2 1:1 bidirectional operation with revertive mode** + +The difference between revertive mode and non-revertive mode is the behavior when the SF or SD condition in the working section is recovered. + +An example is given in Table A.2. + +**Table A.2/G.983.5 – 1:1 bidirectional operation with revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------------|-----------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 1
recovery of
the upstream
SF on
working
section | No failure
traffic is on the working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SF is detected on the
working section at OLT. | | 11000001/00011101 | | Bridge and switch the
working channel to the
protection section. | +| | | 00100001/00011101 | | Bridge and switch the
working channel to the
protection section. | | +| | SF is cleared at OLT.
Revertive mode. | | 01100001/00011101 | | | +| | | | 00000000/00001101 | | Wait to restore is expired.
Bridge and switch the
working channel to the
working section. | +| | | 00000000/00001101 | | Bridge and switch the
working channel to the
working. | | + +**Table A.2/G.983.5 – 1:1 bidirectional operation with revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------|--------------------------------------------------------|-------------------|-------------------|----------------------------------------------------------------------------------------------------|------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 2
Downstream
SD and
recovery on
working
section | No failure
traffic is on working
section. | 00000000/00001101 | 00000000/00001101 | | | +| | SD is detected on the
working section at an
ONU. | 10100001/00011101 | | Bridge and switch the
working channel to the
protection section. | | +| | | | 00100001/00011101 | | Bridge and switch the
working channel to the
protection section. | +| | SD is cleared at ONU. | 01100001/00011101 | | | | +| | | 00000000/00001101 | | Wait to restore is expired.
Bridge and switch the
working channel to the
working section. | | +| | | | 00000000/00001101 | | Bridge and switch the
working channel to the
working section. | + +### **A.4.3 1+1 bidirectional operation with non-revertive mode** + +The difference between 1+1 bidirectional operation with non-revertive mode and 1:1 bidirectional operation with non-revertive mode is the code of K2 byte. The behavior of 1+1 bidirectional operation with non-revertive mode is the same as that of 1:1 bidirectional operation with non-revertive mode. + +An example is given in Table A.3. + +**Table A.3/G.983.5 – 1+1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------|-----------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------------|------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 1
Upstream SF
and recovery
on working
section | No failure
traffic is on the working
section. | 00000000/00000101 | 00000000/00000101 | | | +| | SF is detected on the
working section at OLT. | | 11000001/00010101 | | Bridge and switch the
working channel to the
protection section. | +| | | 00100001/00010101 | | Bridge and switch the
working channel to the
protection section. | | +| | SF is cleared at OLT. Non
revertive mode | | 01100001/00010101 | | | +| | | | 00010001/00010101 | | Wait to restore is expired. | +| | | 00100001/00010101 | | Wait to restore is expired. | | + +**Table A.3/G.983.5 – 1+1 bidirectional operation with non-revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------------------|--------------------------------------------------|-------------------|-------------------|----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 2
Downstream
SF and
recovery on
working
section | No failure
traffic is on working
section. | 00000000/00000101 | 00000000/00000101 | | | +| | SF is detected on the
working section at ONU. | 11000001/00010101 | | Stop the upstream signal on
working section at ONU.
Bridge and switch the
working channel to the
protection section. | | +| | SF is detected on the
working section at OLT. | | 11000001/00010101 | | Detect LOSi .
Bridge and switch the
working channel to the
protection section. | +| | | | 01100001/00010101 | | | +| | SF is cleared at OLT and
ONU. | 01100001/00010101 | 01100001/00010101 | Recover the upstream
signal after ranging. | | + +### **A.4.4 1+1 bidirectional operation with revertive mode** + +The difference between 1+1 bidirectional operation with revertive and 1:1 bidirectional operation with revertive is the code of K2 byte. The behavior of 1+1 bidirectional operation with revertive mode is the same as that of 1:1 bidirectional operation with revertive mode. + +An example is given in Table A.4. + +**Table A.4/G.983.5 – 1+1 bidirectional operation with revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|---------------------------------------------------------------------|-----------------------------------------------------|-------------------|-------------------|------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 1
recovery of
the upstream
SF on
working
section | No failure
traffic is on the working
section. | 00000000/00000101 | 00000000/00000101 | | | +| | SF is detected on the
working section at OLT. | | 11000001/00010101 | | Bridge and switch the
working channel to the
protection section. | +| | | 00100001/00010101 | | Bridge and switch the
working channel to the
protection section. | | +| | SF is cleared at OLT.
Revertive mode. | | 01100001/00010101 | | | +| | | | 00000000/00000101 | | Wait to restore is expired.
Bridge and switch the
working channel to the
working section. | +| | | 00000000/00000101 | | Bridge and switch the
working channel to the
working. | | + +**Table A.4/G.983.5 – 1+1 bidirectional operation with revertive mode example** + +| Scenario | Failure Condition or state | K1/K2 Bytes | | Action | | +|--------------------------------------------------------|--------------------------------------------------|-------------------|-------------------|----------------------------------------------------------------------------------------------|------------------------------------------------------------------| +| | | ONU→OLT | OLT→ONU | ONU | OLT | +| No. 2
Downstream SD and recovery on working section | No failure traffic is on working section. | 00000000/00000101 | 00000000/00000101 | | | +| | SD is detected on the working section at an ONU. | 10100001/00010101 | | Bridge and switch the working channel to the protection section. | | +| | | | 00100001/00010101 | | Bridge and switch the working channel to the protection section. | +| | SD is cleared at ONU. | 01100001/00010101 | | | | +| | | 00000000/00000101 | | Wait to restore is expired.
Bridge and switch the working channel to the working section. | | +| | | | 00000000/00000101 | | Bridge and switch the working channel to the working section. | + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | 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+Digital sections and digital line system – Optical line +systems for local and access networks + +# --- **Gigabit-capable Passive Optical Networks (G-PON): ONT management and control interface specification** + +Recommendation ITU-T G.984.4 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **Recommendation ITU-T G.984.4** + +# **Gigabit-capable Passive Optical Networks (G-PON): ONT management and control interface specification** + +## **Summary** + +Recommendation ITU-T G.984.4 provides the optical network termination (ONT) management and control interface (OMCI) specification for gigabit-capable passive optical network (G-PON) systems as defined in Recommendations ITU-T G.984.2 and G.984.3. + +Firstly, it specifies the managed entities of a protocol-independent management information base (MIB) that models the exchange of information between the optical line termination (OLT) and the optical network termination (ONT). In addition, it covers the ONT management and control channel, protocol and detailed messages. This revised version incorporates the material from Amendment 1 (2005), Amendment 2 (2006), and Amendment 3 (2006). + +In addition to the purely editorial correction work, this revision endeavours to remove all references to the optional ATM transport capabilities of G-PON, since all modern systems do not support it. + +## **Source** + +Recommendation ITU-T G.984.4 was approved on 22 February 2008 by ITU-T Study Group 15 (2005-2008) under Recommendation ITU-T A.8 procedure. + +This edition includes additions and corrections approved on 29 March 2008 by ITU-T Study Group 15 (2005-2008) under the Recommendation ITU-T A.8 procedure. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2009 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +| | | Page | +|------|--------------------------------------------------------------|------| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 4 | +| 4 | Abbreviations and acronyms ..... | 4 | +| 5 | Conventions ..... | 9 | +| 6 | Reference model and terms ..... | 10 | +| 6.1 | OMCI in Recommendation ITU-T G.984.1 ..... | 10 | +| 6.2 | ONT functions ..... | 10 | +| 6.3 | Encapsulation in GEM frame ..... | 11 | +| 6.4 | Support of multicast connection..... | 11 | +| 6.5 | Voice over IP management ..... | 11 | +| 7 | Requirements of the management interface specification ..... | 12 | +| 7.1 | Configuration management ..... | 12 | +| 7.2 | Fault management ..... | 13 | +| 7.3 | Performance management ..... | 13 | +| 7.4 | Security management ..... | 13 | +| 8 | Protocol-independent MIB for the OMCI ..... | 13 | +| 8.1 | Managed entities..... | 14 | +| 8.2 | Managed entity relation diagrams ..... | 21 | +| 9 | MIB description ..... | 46 | +| 9.1 | Equipment management ..... | 49 | +| 9.2 | ANI management..... | 75 | +| 9.3 | Layer 2 data services ..... | 91 | +| 9.4 | Layer 3 data services ..... | 146 | +| 9.5 | Ethernet services..... | 163 | +| 9.6 | 802.11 services ..... | 171 | +| 9.7 | xDSL services..... | 185 | +| 9.8 | TDM services ..... | 243 | +| 9.9 | Voice services..... | 264 | +| 9.10 | MoCA..... | 294 | +| 9.11 | Traffic management..... | 300 | +| 9.12 | General purpose MEs ..... | 303 | +| 9.13 | Miscellaneous services ..... | 314 | +| 10 | ONT management and control channel (OMCC)..... | 329 | +| 11 | ONT management and control protocol ..... | 330 | +| 11.1 | ONT management and control protocol packet format..... | 330 | +| 11.2 | Message flow control and error recovery ..... | 340 | + +| | Page | +|-------------------------------------------------------|-------------| +| 11.3 OMCI handling within the ONT ..... | 342 | +| Appendix I – OMCI common mechanisms and services..... | 344 | +| I.1 Common mechanisms ..... | 344 | +| I.2 Common services ..... | 355 | +| Appendix II – OMCI message set..... | 371 | +| II.1 General remarks..... | 371 | +| II.2 Message layout ..... | 373 | +| Appendix III – Traffic management options..... | 408 | +| III.1 Priority queue configuration..... | 408 | +| III.2 Explicit traffic scheduler configuration..... | 408 | +| III.3 Traffic descriptor configuration ..... | 409 | +| Appendix IV – Video return path ..... | 410 | +| IV.1 Network overview ..... | 410 | +| IV.2 Mode 1 STB-ONT interface..... | 411 | +| IV.3 Mode 1 ONT-network interface ..... | 412 | +| IV.4 Mode 2 STB-ONT interface..... | 413 | +| IV.5 Mode 2 ONT-network interface ..... | 413 | +| Bibliography..... | 420 | + +###### Recommendation ITU-T G.984.4 + +# Gigabit-capable Passive Optical Networks (G-PON): ONT management and control interface specification + +# 1 Scope + +This Recommendation specifies the optical network termination management and control interface (OMCI) for the G-PON system defined in [ITU-T G.984.2] and [ITU-T G.984.3] to enable multi-vendor interoperability between the optical line termination (OLT) and the ONT. + +The OMCI specification addresses the ONT configuration management, fault management and performance management for G-PON system operation and for several services, including: + +- asynchronous transfer mode (ATM) adaptation layer 5; +- G-PON encapsulation method (GEM) adaptation layers; +- circuit emulation service; +- Ethernet services, including MAC bridged LAN; +- voice services; +- wavelength division multiplexing. + +The focus of this OMCI specification is on Fibre to the home (FTTH) and Fibre to the business (FTTBusiness) ONTs; however, support for optical network units (ONUs) is addressed as well. This Recommendation defines a protocol necessary to support the capabilities identified for these ONTs. It also allows optional components and future extensions. + +# 2 References1 + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.707] Recommendation ITU-T G.707/Y.1322 (2007), *Network node interface for the synchronous digital hierarchy (SDH)*. +- [ITU-T G.711] Recommendation ITU-T G.711 (1988), *Pulse code modulation (PCM) of voice frequencies*. +- [ITU-T G.722.1] Recommendation ITU-T G.722.1 (1999), *Coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss*. +- [ITU-T G.722.2] Recommendation ITU-T G.722.2 (2003), *Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB)*. +- [ITU-T G.723.1] Recommendation ITU-T G.723.1 (2006), *Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s*. + +--- + +1 References to implementers' guides in the text of this Recommendation do not give them the status of Recommendations. + +- [ITU-T G.726] Recommendation ITU-T G.726 (1990), *40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM)*. +- [ITU-T G.728] Recommendation ITU-T G.728 (1992), *Coding of speech at 16 kbit/s using low-delay code excited linear prediction*. +- [ITU-T G.729] Recommendation ITU-T G.729 (2007), *Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP)*. +- [ITU-T G.784] Recommendation ITU-T G.784 (1999), *Synchronous digital hierarchy (SDH) management*. +- [ITU-T G.983.2] Recommendation ITU-T G.983.2 (2005), *ONT management and control interface specification for B-PON*. +- [ITU-T G.984.2] Recommendation ITU-T G.984.2 (2003), *Gigabit-capable Passive Optical Networks (G-PON): Physical Media dependent (PMD) layer specification*. +- [ITU-T G.984.3] Recommendation ITU-T G.984.3 (2008), *Gigabit-capable Passive Optical Networks (G-PON): Transmission convergence layer specification*. +- [ITU-T G.992.1] Recommendation ITU-T G.992.1 (1999), *Asymmetric digital subscriber line (ADSL) transceivers*. +- [ITU-T G.992.3] Recommendation ITU-T G.992.3 (2005), *Asymmetric digital subscriber line transceivers 2 (ADSL2)*. +- [ITU-T G.992.4] Recommendation ITU-T G.992.4 (2002), *Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2)*. +- [ITU-T G.992.5] Recommendation ITU-T G.992.5 (2005), *Asymmetric digital subscriber line (ADSL) transceivers – Extended bandwidth ADSL2 (ADSL2plus)*. +- [ITU-T G.993.1] Recommendation ITU-T G.993.1 (2004), *Very high speed digital subscriber line transceivers (VDSL)*. +- [ITU-T G.993.2] Recommendation ITU-T G.993.2 (2006), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [ITU-T G.994.1] Recommendation ITU-T G.994.1 (2003), *Handshake procedures for digital subscriber line (DSL) transceivers*. +- [ITU-T G.997.1] Recommendation ITU-T G.997.1 (2006), *Physical layer management for digital subscriber line (DSL) transceivers*. +- [ITU-T H.248.x] Recommendation ITU-T H.248.x-series (in force), *Gateway control protocol*. +- [ITU-T H.341] Recommendation ITU-T H.341 (1999), *Multimedia management information base*. +- [ITU-T I.363.5] Recommendation ITU-T I.363.5 (1996), *B-ISDN ATM adaptation layer specification: Type 5 AAL*. +- [ITU-T M.3100] Recommendation ITU-T M.3100 (2005), *Generic network information model*. +- [ITU-T T.35] Recommendation ITU-T T.35 (2000), *Procedure for the allocation of ITU-T defined codes for non-standard facilities*. +- [ITU-T T.38] Recommendation ITU-T T.38 (2005), *Procedures for real-time Group 3 facsimile communication over IP networks*. + +- [ATIS-0322000] ATIS-0322000 (2005), *Representation of the Communications Industry Manufacturers, Suppliers, and Related Service Companies for Information Exchange.* +[](http://webstore.ansi.org/RecordDetail.aspx?sku=ATIS-0322000_2005) +- [ANSI T1.PP.413] ANSI T1.PP.413\* (2004), *Network to Customer Installation Interfaces - Asymmetric Digital Subscriber Line (ADSL) Metallic Interface.* +[](http://webstore.ansi.org/RecordDetail.aspx?sku=T1.PP.413-2004) +- [ETSI 101 270-1] ETSI TS 101 270-1 V1.4.1 (2005), *Transmission and Multiplexing (TM); Access transmission systems on metallic access cables; Very high speed Digital Subscriber Line (VDSL); Part 1: Functional requirements.* +[](http://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=19789) +- [ETSI 101 388] ETSI TS 101 388 V1.4.1 (2007), *Access Terminals Transmission and Multiplexing (ATTM); Access transmission systems on metallic access cables; Asymmetric Digital Subscriber Line (ADSL) – European specific requirements.* +[](http://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=27082) +- [IEEE 802] IEEE 802-2001, *IEEE Standard for local and metropolitan area networks – Overview and Architecture.* +[](http://standards.ieee.org/getieee802/download/802-2001.pdf) +- [IEEE 802.1D] IEEE 802.1D-2004, *IEEE Standard for local and metropolitan area networks – Media access control (MAC) Bridges.* +[](http://standards.ieee.org/getieee802/download/802.1D-2004.pdf) +- [IEEE 802.1Q] IEEE 802.1Q-2005, *IEEE Standard for local and metropolitan area networks – Virtual Bridged Local Area Networks.* +[](http://standards.ieee.org/getieee802/download/802.1Q-2005.pdf) +- [IEEE 802.11] IEEE 802.11-2007, *IEEE Standard for local and metropolitan area networks – Specific requirements – Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.* +[](http://standards.ieee.org/getieee802/802.11.html) +- [IETF RFC 815] IETF RFC 815 (1982), *IP Datagram Reassembly Algorithms.* +[](http://www.ietf.org/rfc/rfc0815.txt) +- [IETF RFC 1349] IETF RFC 1349 (1992), *Type of service in the Internet Protocol Suite.* +[](http://www.ietf.org/rfc/rfc1349.txt) +- [IETF RFC 1483] IETF RFC 1483 (1993), *Multiprotocol Encapsulation over ATM Adaptation Layer 5.* +[](http://www.ietf.org/rfc/rfc1483.txt) +- [IETF RFC 2069] IETF RFC 2069 (1997), *An Extension to HTTP: Digest Access Authentication.* +[](http://www.ietf.org/rfc/rfc2069.txt) +- [IETF RFC 2096] IETF RFC 2096 (1997), *IP Forwarding Table MIB.* +[](http://www.ietf.org/rfc/rfc2096.txt?number=2096) +- [IETF RFC 2617] IETF RFC 2617 (1999), *HTTP Authentication: Basic and Digest Access Authentication.* +[](http://www.ietf.org/rfc/rfc2617.txt) + +--- + +\* T1 standards are maintained since November 2003 by ATIS. + +- [IETF RFC 2833] IETF RFC 2833 (2000), *RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals*. + <> +- [IETF RFC 3551] IETF RFC 3551 (2003), *RTP Profile for Audio and Video Conferences with Minimal Control*. + <> +- [IETF RFC 4733] IETF RFC 4733 (2006), *RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals*. + <> +- [IETF RFC 4734] IETF RFC 4734 (2006), *Definition of Events for Modem, Fax, and Text Telephony Signals*. + <> +- [DSLF TR-69] DSLF TR-69 (2007), *CPE WAN Management Protocol*. + <> +- [MEF8] Metro Ethernet Forum MEF8 (2004), *Implementation Agreement for the Emulation of PDH Circuits over Metro Ethernet Networks*. + <> +- [SCTE 55-1] ANSI/SCTE 55-1 (2002), *Digital Broadband Delivery System: Out Of Band Transport Part 1: Mode A*. + <> +- [SCTE 55-2] ANSI/SCTE 55-2 (2002), *Digital Broadband Delivery System: Out Of Band Transport Part 2: Mode B*. + <> + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 downstream:** Downstream is a traffic flow from OLT to ONT. + +**3.2 optical network termination (ONT):** A single subscriber device that terminates any one of the distributed (leaf) endpoints of an ODN, implements a PON protocol, and adapts PON PDUs to subscriber service interfaces. An ONT is a special case of an ONU. + +**3.3 optical network unit (ONU):** A generic term denoting a device that terminates any one of the distributed (leaf) endpoints of an ODN, implements a PON protocol, and adapts PON PDUs to subscriber service interfaces. In some contexts, an ONU implies a multiple subscriber device. + +NOTE – This Recommendation uses the term *ONT* to refer to either configuration unless a distinction is necessary. + +**3.4 upstream:** The upstream is a traffic flow from ONT to OLT. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|-------------------------------------------------------------------------------------------------------------------------------------| +| AAL | Asynchronous transfer mode Adaptation Layer | +| ADSL | Asymmetric Digital Subscriber Line (note that the xDSL MEs include the G.992 family as well as G.993.2 VDSL2, but not G.993.1 VDSL) | +| AES | Advanced Encryption Standard | +| AIS | Alarm Indication Signal | + +| | | +|----------|--------------------------------------------------------------------------| +| AK | Acknowledgement | +| AN | Access Node | +| ANI | Access Node Interface | +| AP | Access Point | +| AR | Acknowledge Request | +| ARC | Alarm Reporting Control | +| ARP | Address Resolution Protocol | +| ASCII | American Standard Code for Information Interchange | +| ATM | Asynchronous Transfer Mode | +| ATU-C | Asymmetric digital subscriber line Transceiver Unit, Central office end | +| ATU-R | Asymmetric digital subscriber line Transceiver Unit, Remote terminal end | +| AVC | Attribute Value Change | +| BER | Bit Error Rate | +| BES | Block Errored Second | +| B-PON | Broadband Passive Optical Network | +| BSS | Basic Service Set | +| CAS | Channel Associated Signalling | +| CCA | Clear Channel Assessment | +| CES | Circuit Emulation Service | +| CFI | Canonical Format Indicator | +| CFP | Contention Free Period | +| CID | Customer/Caller Identification | +| CIR | Committed Information Rate | +| CLEI | Common Language Equipment Identification | +| CLP | Cell Loss Priority | +| CNR | Carrier-to-Noise Ratio | +| CPCS-SDU | Common Part Convergence Sublayer Service Data Unit | +| CPCS-UU | Common Part Convergence Sublayer User-to-User Indication | +| CPI | Common Part Indicator | +| CPS | Common Part Sublayer | +| CRC | Cyclic Redundancy Check | +| CSS | Controlled Slip Second | +| CTB | Composite Triple Beat | +| CTP | Connection Termination Point | +| CTS | Clear To Send | +| DB | Destination Bit | +| DBA | Dynamic Bandwidth Assignment | + +| | | +|-------------|------------------------------------------------------------------| +| DCF | Distributed Coordination Function | +| DEMUX | De-multiplexing | +| DHCP | Dynamic Host Configuration Protocol | +| DSL | Digital Subscriber Line | +| DSSS | Direct-Sequence Spread Spectrum | +| DTIM | Delivery Traffic Indication Message | +| EMF | ElectroMagnetic Field | +| ES | Errored Second | +| ESS | Extended Service Set | +| FEC | Forward Error Correction | +| FHSS | Frequency-Hopping Spread Spectrum | +| FTTB | Fibre to the Building | +| FTTBusiness | Fibre to the Business | +| FTTC | Fibre to the Curb | +| FTTCab | Fibre to the Cabinet | +| FTTH | Fibre to the Home | +| GAL | Gigabit-capable encapsulation method Adaptation Layer | +| GEM | Gigabit-capable Passive Optical Network Encapsulation Method | +| G-PON | Gigabit-capable Passive Optical Network | +| GTC | Gigabit-capable Passive Optical Network Transmission Convergence | +| HEC | Header Error Correction | +| HN | Home Network | +| HOL | Head of the Line | +| IBSS | Independent Basic Service Set | +| ICMP | Internet Control Message Protocol | +| ICV | Integrity Check Value | +| ID | Identifier | +| IF | Interface | +| IGMP | Internet Group Management Protocol | +| IP | Internet Protocol | +| IR | InfraRed | +| ISDN | Integrated Services Digital Network | +| IW | Interworking | +| LAN | Local Area Network | +| LCT | Local Craft Terminal | +| LIM | Line Interface Module | +| LME | Sublayer Management Entity | + +| | | +|-------|--------------------------------------------------------------| +| LMI | Layer Management Indication | +| LMIG | Layer Management Indication Generation | +| LMIR | Layer Management Indication Receiving | +| LOS | Loss of Signal | +| LSB | Least Significant Bit | +| LT | Line Terminal | +| MAC | Media Access Control | +| MCM | Multiple Carrier Modulation | +| ME | Managed Entity | +| MIB | Management Information Base | +| MLT | Mechanized Loop Testing | +| MMPDU | Media access control Management Protocol Data Unit | +| MoCA | Multimedia over Coax Alliance | +| MPDU | Media access control Protocol Data Unit | +| MSB | Most Significant Bit | +| MSDU | Media access control Service Data Unit | +| MT | Message Type | +| MTU | Maximum Transmission Unit | +| MUX | Multiplexing | +| NMS | Network Management System | +| NSCds | Number of SubCarriers – downstream | +| NSCus | Number of SubCarriers – upstream | +| NT | Network Terminal | +| OAN | Optical Access Network | +| ODN | Optical Distribution Network | +| OLT | Optical Line Terminal | +| OMCC | Optical network termination Management and Control Channel | +| OMCI | Optical network termination Management and Control Interface | +| ONT | Optical Network Termination | +| ONU | Optical Network Unit | +| OpS | Operations System | +| PCF | Point Coordination Function | +| PHY | Physical interface | +| PIR | Peak Information Rate | +| PLCP | Physical Layer Convergence Protocol | +| PLOAM | Physical Layer Operations, Administration and Maintenance | +| PM | Performance Monitoring | + +| | | +|--------|----------------------------------------------------| +| PMD | Physical Medium Dependent | +| PMS-TC | Physical Media Specific – Transmission Convergence | +| PON | Passive Optical Network | +| POTS | Plain Old Telephone Service | +| PPTP | Physical Path Termination Point | +| PSD | Power Spectral Density | +| PSN | Packet Switched Network | +| PVC | Permanent Virtual Circuit | +| QoS | Quality of Service | +| RDI | Remote Defect Indication | +| RF | Radio Frequency | +| RFI | Radio Frequency Interference | +| RM | Resource Management | +| RTCP | Real-time Transport Control Protocol | +| RTP | Real Time Protocol | +| RTS | Request To Send | +| SAR | Segmentation And Reassembly | +| SCM | Single Carrier Modulation | +| SES | Severely Errored Second | +| SIFS | Short Interframe Space | +| SIP | Session Initiation Protocol | +| SME | Station Management Entity | +| SN | Service Node | +| SNI | Service Node Interface | +| SNR | Signal-to-Noise Ratio | +| SSCS | Service Specific Convergence Sublayer | +| STA | Station | +| TC | Transmission Convergence | +| TCA | Threshold Crossing Alert | +| TCI | Tag Control Information | +| T-CONT | Transmission Container | +| TCP | Transmission Control Protocol | +| TDM | Time Division Multiplex | +| TE | Terminal Equipment | +| TOS | Type of Service | +| TP | Termination Point | +| TU | Time Unit | + +| | | +|-------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TU | Tributary Unit | +| UAS | UnAvailable Second | +| UDP | User Datagram Protocol | +| UNI | User Network Interface | +| UPC | Usage Parameter Control | +| VBR | Variable Bit Rate | +| VC | Virtual Circuit | +| VC | Virtual Container (synchronous digital hierarchy) | +| VCC | Virtual Circuit Connection | +| VCI | Virtual Circuit Identifier | +| VDSL | Very high speed Digital Subscriber Line (note that G.993.2 VDSL2 is managed under the xDSL family of MEs) | +| VID | Virtual Local Area Network Identifier | +| VLAN | Virtual Local Area Network | +| VoIP | Voice over Internet Protocol | +| VP | Virtual Path | +| VPC | Virtual Path Connection | +| VPI | Virtual Path Identifier | +| VRP | Video Return Path | +| VTU-O | Very high speed Digital Subscriber Line Transceiver Unit, Optical network termination end | +| VTU-R | Very high speed Digital Subscriber Line Transceiver Unit, Remote terminal end | +| WEP | Wired Equivalent Privacy | +| WRR | Weighted Round Robin | +| xDSL | x Digital Subscriber Line | +| xTU-C | x digital subscriber line Transceiver Unit at the Central office end (in the case of PON, the ONT), used as a generic term referring to both the ATU-C of Recommendations ITU-T G.992.x-series and the VTU-O of Recommendation ITU-T G.993.2. | +| xTU-R | x digital subscriber line Transceiver Unit at the Remote end (subscriber premises), used as a generic term referring to both the ATU-R of Recommendations ITU-T G.992.x-series and the VTU-R of Recommendation ITU-T G.993.2. | + +# 5 Conventions + +In all bit vectors indicated in this Recommendation, the rightmost bit is bit 1. This represents the least significant bit, while bit 8 represents the most significant bit within a byte. If the bit vector is made up of more than one byte, then the numbering starts from the least significant byte onwards. + +In all attribute descriptions that refer to the Boolean values "true" and "false," true is coded as 0x01 in hexadecimal and false is coded as 0. + +In all attribute descriptions that refer to spaces, the value 0x20 must be used for the entire size of the attribute. + +"ASCII string" is a sequence of ASCII encoded characters, terminated by the NULL character (0x00). If a string occupies the entire allocated size of an attribute, the terminating null is not required. + +# 6 Reference model and terms + +## 6.1 OMCI in Recommendation ITU-T G.984.1 + +The network architecture reference model for G-PON is described in [b-ITU-T G.984.1] and shown in Figure 6.1-1. The G-PON fits various access network architectures, e.g., FTTH, FTTB/C and FTTCab. + +The OMCI specification fits into the overall [b-ITU-T G.984.1] model for an access network system as illustrated in Figure 6.1-1. The dotted line shows a path for OMCI signals between an OLT and ONT. + +![Figure 6.1-1 – Reference model diagram showing the network architecture for G-PON. It includes components like TE, HN, ONT, NT, ONU, ODN, OLT, and AN management system, with interfaces labeled UNI, xDSL, and PON. A legend at the bottom left defines the line types: solid for physical links and dashed for ONT management and control interfaces.](41a438d7e4adc17c3a4005e7c9500091_img.jpg) + +The diagram illustrates the reference model for G-PON. On the left, there are two sets of user equipment. The top set consists of three TE (Terminal Equipment) blocks connected to a single HN (Home Network) circle, which is in turn connected to an ONT (Optical Network Terminal). The bottom set consists of two TE blocks connected to an HN circle, which connects to an NT (Network Terminal). This NT connects to an ONU (Optical Network Unit), which also connects to another NT, which in turn connects to two more TE blocks. The ONT and the ONU are connected to a central ODN (Optical Distribution Network) block. The ODN is connected to an OLT (Optical Line Terminal). Above the OLT is an AN management system, connected via a Q3 interface. Dashed lines represent the ONT management and control interface (OMCI) path, originating from the AN management system, passing through the OLT, and branching out to both the ONT and the ONU. Solid lines represent physical links between the various components. Vertical dashed lines divide the diagram into sections labeled UNI, xDSL interface, PON interface, and PON interface. The label G.984.4(08)\_F6.1-1 is in the bottom right corner. A legend at the bottom left shows a solid line for 'Physical link' and a dashed line for 'ONT management and control interface'. + +Figure 6.1-1 – Reference model diagram showing the network architecture for G-PON. It includes components like TE, HN, ONT, NT, ONU, ODN, OLT, and AN management system, with interfaces labeled UNI, xDSL, and PON. A legend at the bottom left defines the line types: solid for physical links and dashed for ONT management and control interfaces. + +Figure 6.1-1 – Reference model + +## 6.2 ONT functions + +As shown in Figure 6.2-1, the functions of the ONT are: + +- access network line termination function (AN-LT); +- user network interface line termination function (UNI-LT), noting that in the fibre to the business case the UNIs from one ONT may belong to different users; +- service multiplexing and de-multiplexing function (service MUX and DEMUX). + +![Figure 6.2-1 – ONT functional block diagram. The diagram shows an ONT (Optical Network Terminal) block. On the left, an 'ANI' (Optional ANI can be supported for survivability function) is connected to an 'AN-LT' (Access Network Link Terminal). The 'AN-LT' is connected to a 'Service MUX and DEMUX'. The 'Service MUX and DEMUX' is connected to multiple 'UNI LT' (User Network Interface Link Terminal) blocks, each of which is connected to a 'UNI' (User Network Interface). The diagram is labeled 'G.984.4(08)_F6.2-1'.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +Figure 6.2-1 – ONT functional block diagram. The diagram shows an ONT (Optical Network Terminal) block. On the left, an 'ANI' (Optional ANI can be supported for survivability function) is connected to an 'AN-LT' (Access Network Link Terminal). The 'AN-LT' is connected to a 'Service MUX and DEMUX'. The 'Service MUX and DEMUX' is connected to multiple 'UNI LT' (User Network Interface Link Terminal) blocks, each of which is connected to a 'UNI' (User Network Interface). The diagram is labeled 'G.984.4(08)\_F6.2-1'. + +**Figure 6.2-1 – ONT functional block diagram** + +## 6.3 Encapsulation in GEM frame + +As the GEM is embedded in the PON section, it is independent of the types of UNIs. The UNI traffic is always encapsulated in GEM frames so that a cross-connect function is not needed in GEM service. + +## 6.4 Support of multicast connection + +Multicast traffic can be supported in a G-PON network. While a port-ID is assigned to a single UNI in a unicast connection, a port-ID is shared by multiple UNIs in multiple ONTs in a multicast connection. The multicast connection set-up process is the same as the unicast connection set-up process. It is the responsibility of the OLT to manage the members of a multicast group and control the multicast connection in ONTs. + +In the downstream direction, a multicast connection is useful for bandwidth savings. On the other hand, in the upstream direction, it is impossible to support the multicast connection with a shared port-ID because the OLT cannot reassemble segmented GEM packets correctly when it receives several GEM packets with same port-ID from different ONTs. Therefore, upstream traffic associated with a multicast service must be sent to the OLT over a separate unicast connection. + +## 6.5 Voice over IP management + +While OMCI is always used to manage PON services and ONT equipment, VoIP services may optionally be managed by means external to OMCI. This allows operators more flexibility in choosing how to manage their overall VoIP service regardless of the access technology involved. VoIP service on an ONT may be managed via one of two paths: + +- 1) OMCI path – OMCI has full view and control of all VoIP service attributes. +- 2) IP path – OMCI is only used to configure attributes that allow non-OMCI based control of VoIP service attributes. + +Specifically, if the OMCI path is used to manage a VoIP service, all of the managed entities defined here may be read and/or written. + +If the IP path is used to manage a SIP VoIP service, only the following MEs may be read and/or written with respect to the VoIP service (all other MEs are unaffected, of course): + +- IP host config data; +- IP host PM history data; +- VoIP config data; +- PPTP POTS UNI; +- Call control PM history data; + +- RTP PM history data; +- SIP call initiation PM history data; +- SIP agent PM history data; +- SIP config portal; +- VoIP line status. + +If the IP path is used to manage a H.248 VoIP service, only the following MEs may be read and/or written with respect to the VoIP service (all other MEs are unaffected, of course): + +- IP host config data; +- IP host PM history data; +- VoIP config data; +- PPTP POTS UNI; +- Call control PM history data; +- RTP PM history data; +- MGC PM history data; +- H.248 config portal; +- VoIP line status. + +# 7 Requirements of the management interface specification + +The OMCI is used by the OLT to control an ONT. This protocol allows the OLT to: + +- a) establish and release connections across the ONT; +- b) manage the UNIs at the ONT; +- c) request configuration information and performance statistics; +- d) autonomously inform the system operator of events such as link failures. + +The OMCI protocol runs across a GEM connection between the OLT controller and the ONT controller that is established at ONT initialization (note that the option of using an ATM connection for OMCI is deprecated). The OMCI protocol is asymmetric: the controller in the OLT is the master and the one in the ONT is the slave. A single OLT controller using multiple instances of the protocol over separate control channels may control multiple ONTs. + +The ONT management and control interface requirements given in this Recommendation are needed to manage the ONT in the following areas: + +- a) configuration management; +- b) fault management; +- c) performance management; +- d) security management. + +## 7.1 Configuration management + +Configuration management provides functions to exercise control over, identify, collect data from and provide data to the ONT. This involves the following: + +- a) configuration of equipment; +- b) configuration of the UNIs; +- c) configuration of the GEM port network CTPs; +- d) configuration of interworking termination points; + +- e) configuration of the OAM flows; +- f) configuration of the physical ports; +- g) configuration of GAL profiles; +- h) configuration of service profiles; +- i) configuration of traffic descriptors; +- j) configuration of AAL profile, in a limited sense. + +All ONTs should support GEM transport of user traffic, and the ATM transport mode is deprecated. There is only one connection model for GEM transport, which is the simple point-to-point transfer of user data via a GEM connection across the PON. GEM interworking always occurs in the OLT and the ONT, and GEM never extends beyond the PON link. + +In the special case where the ONT supports an ATM UNI (ADSL is the notable example), the ATM connection from the customer must be terminated by the ONT. In this case, the OMCI also supports the required configuration methods to manage this function. + +## 7.2 Fault management + +The ONT supports *limited* fault management only. Most of the operations are limited to failure indication. The OMCI supports failure reporting on many managed entities that are described throughout clause 9. An alarm table is defined for each of these entities. + +To avoid erratic floods of alarm messages, it is common to filter, or soak, defects such as facility impairments before declaring them as alarms, and to soak defect clearing before retiring the alarm. The declaration soak time is typically $2.5 \pm 0.5$ seconds, while the retirement soak time is typically $10.5 \pm 0.5$ seconds. Which alarms are to be soaked, and what the soak intervals should be, are regarded as vendor-specific choices. Interoperability considerations, however, require that alarms be soaked at exactly one of the OLT or ONT, and this Recommendation specifies that they be soaked at the ONT. + +## 7.3 Performance management + +The ONT has only *limited* performance monitoring. The OMCI supports performance monitoring using a subset of managed entities that are described throughout clause 9. These managed entities can be identified by the words "performance monitoring history data" in their names. + +Note that all performance monitoring related managed entities are created at the request of the OLT. + +All history data shall be maintained in the OLT. + +## 7.4 Security management + +[ITU-T G.984.3] specifies some mechanisms from the viewpoint of security. That includes the downstream data encryption of the ONT. The ONT2-G managed entity can enable/disable the downstream encryption function. + +This Recommendation supports the protection function. The type C protection configuration that is defined in [b-ITU-T G.984.1] is considered in this Recommendation. As the switching behaviour for PON protection will be done in the TC layer, this Recommendation defines a managed entity to specify the protection capability. + +# 8 Protocol-independent MIB for the OMCI + +The OMCI should be defined to allow vendors to offer modular, incremental capabilities to meet different levels of customer needs. This Recommendation defines a protocol necessary to support capabilities identified by [ITU-T G.984.2] and [ITU-T G.984.3]. It is important for interoperability, yet it allows for optional components and future extensions. + +A protocol-independent MIB is used to describe the exchange of information across the OMCI. It forms the basis from which protocol-specific models are defined. This MIB has as much commonality as possible with the related generic MIB as defined in other ITU-T Recommendations. It is intended to make the OMCI relatively simple while maintaining consistency with the MIB used by the interface between the network-element manager and the OLT. + +## 8.1 Managed entities + +The protocol-independent MIB presented in this Recommendation is defined in terms of *managed entities*. The managed entities are abstract representations of resources and services in an ONT. + +This Recommendation uses three levels for indicating the degree of compliance necessary for specific functions and managed entities associated with the OMCI specification: + +- **Requirement (R):** Entities necessary for operational compatibility. +- **Conditional requirements (CR):** Entities necessary when the specified optional function is implemented. +- **Option (O):** Entities that may be useful and required by an operator but that are not necessary for operational compatibility. + +The possible managed entities are listed in Table 8-1. This table also shows the clause within this Recommendation that defines each ME. + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/optional | Description | Clause | +|--------------------------------------------------|-------------------|------------------------------------------------------------------------------------------------------------------|---------| +| 802.11 general purpose object | CR | Used for 802.11 interface supported by the ONT | 9.6.4 | +| 802.11 MAC and PHY operation and antenna data | CR | Used for 802.11 interface supported by the ONT | 9.6.5 | +| 802.11 performance monitoring history data | O | Used for 802.11 interface supported by the ONT | 9.6.7 | +| 802.11 PHY FHSS DSSS IR tables | CR | Used for 802.11 interface supported by the ONT | 9.6.6 | +| 802.11 station management data 1 | CR | Used for 802.11 interface supported by the ONT | 9.6.2 | +| 802.11 station management data 2 | CR | Used for 802.11 interface supported by the ONT | 9.6.3 | +| 802.1p mapper service profile | CR | Used for 802.1p priority Ethernet UNI | 9.3.10 | +| AAL 5 performance monitoring history data | CR | Used for DSL ATM mode interworking | 9.13.6 | +| AAL 5 profile | CR | Used for DSL ATM mode interworking | 9.13.5 | +| ANI-G | R | Used for ANI management | 9.2.1 | +| ARP configuration data | CR | Used for IP port supported by the ONT | 9.4.11 | +| ARP service profile | CR | Used for IP port supported by the ONT | 9.4.10 | +| Attribute | CR | Used when OMCI self-description is supported | 9.12.10 | +| Authentication security method | O | Used for the user id/password configuration to associate an IP session between the client and destination server | 9.12.4 | +| Call control performance monitoring history data | O | Used for call control performance monitoring history. Member of VoIPData group | 9.9.12 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|------------------------------------------------------------|-------------------------------|--------------------------------------------------------------------------------------------------------------------------------------|---------------| +| Cardholder | CR | Used for a circuit pack plug-in slot. Can also represent a virtual cardholder to distinguish types of ports in an integrated ONT | 9.1.5 | +| CES physical interface performance monitoring history data | O | Used for CES interface performance monitoring | 9.8.4 | +| CES service profile-G | CR | Used for CES services supported by the ONT | 9.8.3 | +| Circuit pack | CR | Used for a plug-in circuit pack module. Can also represent a virtual circuit pack to distinguish types of ports in an integrated ONT | 9.1.6 | +| Dot1 rate limiter | CR | Provides for limiting and policing upstream traffic | 9.3.18 | +| Dot1ag CFM stack | O | Supports 802.1ag configuration fault management | 9.3.25 | +| Dot1ag chassis-management info | O | Supports 802.1ag configuration fault management | 9.3.26 | +| Dot1ag default MD level | O | Supports 802.1ag configuration fault management | 9.3.21 | +| Dot1ag maintenance association | O | Supports 802.1ag configuration fault management | 9.3.20 | +| Dot1ag maintenance domain | O | Supports 802.1ag configuration fault management | 9.3.19 | +| Dot1ag MEP | O | Supports 802.1ag configuration fault management | 9.3.22 | +| Dot1ag MEP CCM database | O | Supports 802.1ag configuration fault management | 9.3.24 | +| Dot1ag MEP status | O | Supports 802.1ag configuration fault management | 9.3.23 | +| Dot1X configuration profile | CR | Used for 802.1X control | 9.3.15 | +| Dot1X performance monitoring history data | CR | Used for 802.1X control | 9.3.16 | +| Dot1X port extension package | CR | Used for 802.1X control | 9.3.14 | +| Equipment extension package | O | Used for additional attributes that may be associated with an ONT or cardholder | 9.1.9 | +| Equipment protection profile | CR | Defines equipment protection groups | 9.1.11 | +| Ethernet flow termination point | CR | Used when the ONT supports the pseudowire function over layer 2 | 9.8.9 | +| Ethernet performance monitoring history data | O | Used for Ethernet interface performance monitoring | 9.5.2 | +| Ethernet performance monitoring history data 2 | O | Used for Ethernet performance monitoring | 9.5.3 | +| Ethernet performance monitoring history data 3 | O | Used for Ethernet performance monitoring (RMON) | 9.5.4 | +| Extended VLAN tagging operation configuration data | CR | Contains configuration parameters for enhanced VLAN operations, including adding, removing and changing multiple tags | 9.3.13 | +| FEC performance monitoring history data | O | Performance monitoring data for FEC on an ANI-G | 9.2.11 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|-------------------------------------------------------------|-------------------------------|------------------------------------------------------------------------------------------------------------------|---------------| +| GAL Ethernet performance monitoring history data | O | Used when GAL Ethernet layer performance monitoring is supported | 9.2.8 | +| GAL Ethernet profile | O | Used when the ONT supports GAL Ethernet | 9.2.7 | +| GAL TDM performance monitoring history data | O | Used when GAL TDM layer performance monitoring is supported | 9.2.10 | +| GAL TDM profile | O | Used when the ONT supports GAL TDM | 9.2.9 | +| GEM interworking termination point | CR | Used for non-ATM UNIs and GEM-based connections | 9.2.4 | +| GEM port network CTP | CR | Used for GEM port termination | 9.2.3 | +| GEM port performance monitoring history data | O | Used for GEM port performance monitoring | 9.2.6 | +| GEM traffic descriptor | CR | Used for GEM-based connections | 9.11.3 | +| General purpose buffer | O | Used to return large blocks of data; structure defined with each specific application | 9.12.12 | +| ICMP performance monitoring history data 1 | O | Used for ICMP performance monitoring | 9.4.8 | +| ICMP performance monitoring history data 2 | O | Used for ICMP performance monitoring | 9.4.9 | +| Interworking VCC termination point | CR | Used for DSL ATM mode interworking | 9.13.4 | +| IP host config data | CR | Used to define the Internet protocol service that may be used with a MAC bridge port. Member of IPHostData group | 9.4.12 | +| IP host performance monitoring history data | O | Used to hold PM counters and alarms for the IP host. Member of IPHostData group | 9.4.13 | +| IP port configuration data | CR | Used for IP port supported by the ONT | 9.4.3 | +| IP route table | CR | Used for IP router supported by the ONT | 9.4.4 | +| IP router configuration data | CR | Used for IP router supported by the ONT | 9.4.2 | +| IP router performance monitoring history data 1 | O | Used for IP router performance monitoring | 9.4.6 | +| IP router performance monitoring history data 2 | O | Used for IP router performance monitoring | 9.4.7 | +| IP router service profile | CR | Used for IP router supported by the ONT | 9.4.1 | +| IP static routes | CR | Used for IP router supported by the ONT | 9.4.5 | +| Large string | CR | Used to hold a character string larger than 25 bytes and up to 375 bytes | 9.12.5 | +| Logical N x 64 kbit/s sub-port connection termination point | CR | Used as logical interface for structured CES | 9.8.2 | +| MAC bridge configuration data | CR | Used for MAC bridge supported by the ONT | 9.3.2 | +| MAC bridge performance monitoring history data | O | Used for MAC bridge performance monitoring | 9.3.3 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|-----------------------------------------------------|-------------------------------|-------------------------------------------------------------------------------------------------------------------|---------------| +| MAC bridge port bridge table data | CR | Used for MAC bridge supported by the ONT | 9.3.8 | +| MAC bridge port configuration data | CR | Used to organize and record data associated with a bridge port | 9.3.4 | +| MAC bridge port designation data | CR | Used for MAC bridge supported by the ONT | 9.3.5 | +| MAC bridge port filter preassign table | O | Used for Ethernet type filtering | 9.3.7 | +| MAC bridge port filter table data | CR | Used for MAC bridge supported by the ONT | 9.3.6 | +| MAC bridge port performance monitoring history data | O | Used for MAC bridge port performance monitoring | 9.3.9 | +| MAC bridge service profile | CR | Used for MAC bridge supported by the ONT | 9.3.1 | +| Managed entity | CR | Used when OMCI self-description is supported | 9.12.9 | +| MGC config data | CR | Used for configuration data associated with an MGC client. Member of H248relatedData group | 9.9.16 | +| MGC config portal | CR | Used to view H.248 configuration when the IP path is being used to manage H.248. Member of H248relatedData group | 9.9.20 | +| MGC performance monitoring history data | O | Used for run-time attributes and statistics associated with an active MGC client. Member of H248relatedData group | 9.9.17 | +| MoCA Ethernet performance monitoring history data | O | Performance monitoring data for the Ethernet layer on the MoCA interface | 9.10.2 | +| MoCA interface performance monitoring history data | O | Performance monitoring data for the physical layer on the MoCA interface | 9.10.3 | +| Multicast GEM interworking termination point | CR | Used to manage multicasting support for GEM connection | 9.2.5 | +| Multicast operations profile | CR | Used to manage multicast at the ONT | 9.3.27 | +| Multicast subscriber config info | CR | Used to manage multicast at the ONT | 9.3.28 | +| Multicast subscriber monitor | O | Used to manage multicast at the ONT | 9.3.29 | +| Network address | CR | Used to bind a network address (URI, IP address) to its associated security method. Member of IPHostData group | 9.12.3 | +| Network dial plan table | O | Used to support network-defined dial plans. Member of VoIPData group | 9.9.10 | +| Octet string | O | Allows for strings of up to 375 arbitrary octet values | 9.12.11 | +| OLT-G | O | Used for OLT identification for interoperability facilitation | 9.12.2 | +| OMCI | CR | Used when OMCI self-description is supported | 9.12.8 | +| ONT data | R | Used for OMCI MIB management | 9.1.3 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|-------------------------------------------------|-------------------------------|-----------------------------------------------------------------------------------------------|---------------| +| ONT power shedding | CR | Used to control the power shedding service | 9.1.7 | +| ONT remote debug | CR | Used to allow remote debugging of an ONT | 9.1.12 | +| ONT2-G | R | Used for ONT equipment management | 9.1.2 | +| ONT-G | R | Used for ONT equipment management | 9.1.1 | +| Physical path termination point 802.11 UNI | CR | Used for 802.11 interface supported by the ONT | 9.6.1 | +| Physical path termination point CES UNI | CR | Used for physical path termination point at the CES UNI | 9.8.1 | +| Physical path termination point Ethernet UNI | CR | Used for physical path termination point at the Ethernet UNI | 9.5.1 | +| Physical path termination point ISDN UNI | O | Used for ISDN port supported by the ONT | 9.9.21 | +| Physical path termination point LCT UNI | O | Used for local craft terminal port | 9.13.3 | +| Physical path termination point MoCA UNI | CR | Used for the physical path termination point for MoCA interfaces | 9.10.1 | +| Physical path termination point POTS UNI | CR | Used for physical path trail termination point at the POTS UNI | 9.9.1 | +| Physical path termination point video ANI | O | Used for optical RF video input port | 9.13.2 | +| Physical path termination point video UNI | O | Used for electrical video output port | 9.13.1 | +| Physical path termination point xDSL UNI part 1 | CR | Used for the physical path termination point at an xDSL CO modem | 9.7.1 | +| Physical path termination point xDSL UNI part 2 | CR | Used for the physical path termination point at an xDSL CO modem | 9.7.2 | +| Port mapping package-G | O | Used to map heterogeneous ports to an equipment entity | 9.1.8 | +| Priority queue-G | CR | Used for ONTs that support priority queues to multiplex ATM or GEM traffic flows | 9.11.1 | +| Protection data | CR | Used for PON protection | 9.1.10 | +| Pseudowire maintenance profile | CR | Used when the ONT supports the pseudowire function | 9.8.7 | +| Pseudowire performance monitoring history data | CR | Used when the ONT supports the pseudowire function | 9.8.8 | +| Pseudowire termination point | CR | Used when the ONT supports the pseudowire function | 9.8.5 | +| Radius performance monitoring history data | CR | Used for 802.1X radius client PM | 9.3.17 | +| RTP performance monitoring history data | O | Used to hold the last completed 15 minutes interval PM data for RTP. Member of VoIPData group | 9.9.13 | +| RTP profile data | CR | Used for RTP configuration for VoIP service | 9.9.7 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|---------------------------------------------------------|-------------------------------|-------------------------------------------------------------------------------------------------------------|---------------| +| RTP pseudowire parameters | CR | Used when the ONT supports the pseudowire function | 9.8.6 | +| SIP agent config data | CR | Used to define a VoIP SIP agent configuration. Member of SIPrelatedData group | 9.9.3 | +| SIP agent performance monitoring history data | O | Used for statistics for the VoIP SIP agent. Member of SIPrelatedData group | 9.9.14 | +| SIP call initiation performance monitoring history data | O | Used for statistics for the VoIP SIP agent. Member of SIPrelatedData group | 9.9.15 | +| SIP config portal | CR | Used to view SIP configuration when the IP path is being used to manage SIP. Member of SIPrelatedData group | 9.9.19 | +| SIP user data | CR | Used for user (subscriber) specific SIP data. Member of SIPrelatedData group | 9.9.2 | +| Software image | R | Used for the software image of the ONT or its components that contain independently manageable software | 9.1.4 | +| TC adaptor performance monitoring history data xDSL | O | Performance monitoring data for the xDSL ATM data path | 9.7.25 | +| T-CONT | R | Used for DBA | 9.2.2 | +| TCP/UDP config data | CR | Used for the TCP or UDP configuration for a TCP/UDP service. Member of IPHostData group | 9.4.14 | +| Threshold data 1 | CR | Used for PM threshold values | 9.12.6 | +| Threshold data 2 | CR | Used for PM threshold values | 9.12.7 | +| Traffic scheduler-G | CR | Used for DBA | 9.11.2 | +| TU CTP | CR | Organizes data that describes the VC path adaptation processing functions of the ONT for SDH services | 9.8.10 | +| TU performance monitoring history data | O | Performance monitoring data collected as a result of TU connection monitoring | 9.8.11 | +| UNI-G | CR | Used for user network interface for GEM service | 9.12.1 | +| VDSL2 line configuration extensions | CR | Contains xDSL attributes unique to VDSL2 (G.993.2) | 9.7.6 | +| VDSL2 line inventory and status data part 1 | CR | Contains additional test and status attributes for xDSL lines, specifically, extensions for VDSL2 | 9.7.16 | +| VDSL2 line inventory and status data part 2 | CR | Contains additional test and status attributes for xDSL lines, specifically, extensions for VDSL2 | 9.7.17 | +| VDSL2 line inventory and status data part 3 | CR | Contains additional test and status attributes for xDSL lines, specifically, extensions for VDSL2 | 9.7.18 | +| Video return path performance monitoring history data | CR | Used for video return path management | 9.13.8 | +| Video return path service profile | CR | Used for video return path management | 9.13.7 | +| VLAN tagging filter data | O | Used for VLAN tagging | 9.3.11 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|--------------------------------------------|-------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------| +| VLAN tagging operation configuration data | O | Used for VLAN tagging | 9.3.12 | +| Voice service profile | CR | Used for voice | 9.9.6 | +| VoIP application service profile | O | Used for VoIP calling feature services. Member of VoIPData group | 9.9.8 | +| VoIP config data | CR | Used to discover VoIP signalling protocols supported and select a VoIP signalling to use. Also used to select a VoIP configuration method. Member of VoIPData group | 9.9.18 | +| VoIP feature access codes | O | Used to define feature access codes for a POTS port. Member of VoIPData group | 9.9.9 | +| VoIP line status | O | Used for VoIP line status that relates to a POTS port. Member of VoIPData group | 9.9.11 | +| VoIP media profile | CR | Used to define codec and other media selection criteria. Member of VoIPData group | 9.9.5 | +| VoIP voice CTP | CR | Used for VoIP voice channel termination point. Member of VoIPData group | 9.9.4 | +| VP network CTP-G | CR | Used for DSL ATM mode interworking | 9.13.9 | +| VP performance monitoring history data | CR | Used for DSL ATM mode interworking | 9.13.10 | +| xDSL channel configuration profile | CR | Contains configuration for an xDSL channel | 9.7.7 | +| xDSL channel downstream status data | CR | Contains status on a downstream xDSL channel | 9.7.19 | +| xDSL channel upstream status data | CR | Contains status on an upstream xDSL channel | 9.7.20 | +| xDSL downstream RFI bands profile | CR | Contains information on the downstream RFI bands | 9.7.11 | +| xDSL line configuration profile part 1 | CR | Contains line parameters for an xDSL line | 9.7.3 | +| xDSL line configuration profile part 2 | CR | Contains line parameters for an xDSL line | 9.7.4 | +| xDSL line configuration profile part 3 | CR | Contains line parameters for an xDSL line | 9.7.5 | +| xDSL line inventory and status data part 1 | CR | Contains inventory and status information on an xDSL line | 9.7.12 | +| xDSL line inventory and status data part 2 | CR | Contains inventory and status information on an xDSL line | 9.7.13 | +| xDSL line inventory and status data part 3 | CR | Contains additional test and status attributes for xDSL lines | 9.7.14 | +| xDSL line inventory and status data part 4 | CR | Contains additional test and status attributes for xDSL lines | 9.7.15 | +| xDSL PSD mask profile | CR | Contains PSD masking information | 9.7.10 | + +**Table 8-1 – Managed entities of the OMCI** + +| Managed entity | Required/
optional | Description | Clause | +|--------------------------------------------------------|-------------------------------|-------------------------------------------------------------|---------------| +| xDSL subcarrier masking downstream profile | CR | Contains masking information for the downstream subcarriers | 9.7.8 | +| xDSL subcarrier masking upstream profile | CR | Contains masking information for the upstream subcarriers | 9.7.9 | +| xDSL xTU-C channel performance monitoring history data | O | Performance monitoring data for an xDSL xTU-C channel | 9.7.23 | +| xDSL xTU-C performance monitoring history data | O | Performance monitoring data for an xDSL xTU-C modem path | 9.7.21 | +| xDSL xTU-R channel performance monitoring history data | O | Performance monitoring data for an xDSL xTU-R channel | 9.7.24 | +| xDSL xTU-R performance monitoring history data | O | Performance monitoring data for an xDSL xTU-R modem path | 9.7.22 | + +## 8.2 Managed entity relation diagrams + +The relationships between the required managed entities are given in the following figures. Figure 8.2-1 gives the legend of symbols used in these diagrams. Note that the threshold data 1/2 managed entity may be associated with any managed entity that has thresholded counters (the PM history data MEs). This is indicated by a special symbol to reduce congestion on the figures. Also note that several managed entities in the figures are optional or conditionally required; hence, they may not be used in some implementations. + +![Legend for managed entity relation diagrams showing various entity types and relationship types between Managed entity A and Managed entity B.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg) + +The diagram illustrates various managed entity types and relationship types: + +- Managed entity A** (rectangular box): Entity created by the ONT +- Managed entity B** (rounded rectangle): Entity created by the OLT +- Managed entity C** (rounded rectangle with double-line sides): Entity created by the ONT or the OLT +- Managed entity D** (scalloped-edge rectangle): A performance monitoring (PM) entity, always created by the OLT, and associated with an instance of threshold data B-PON +- Managed entity A → Managed entity B** (solid arrow): Entity A has explicit pointer to entity B +- Managed entity A --- Managed entity B** (dashed line): Entity A has implicit ID relationship to entity B (ME IDs are equal, or use structured numbering) +- Managed entity A (1) → (0..X) Managed entity B** (solid arrow with cardinality): There can be 0..X instances of A related to B +- Managed entity A (1) --- (1) Managed entity B** (dashed line with cardinality): There is a 1 to 1 relationship of A to B +- OR** (circle on connection lines): Only one of the connections shown is active for any one instance + +G.984.4(08)\_F8.2-1 + +Legend for managed entity relation diagrams showing various entity types and relationship types between Managed entity A and Managed entity B. + +**Figure 8.2-1 – Legend for managed entity relation diagrams** + +### 8.2.1 ONT common functions + +![A complex block diagram of the ONT core showing various functional blocks and their interconnections with multiplicities.](2bacc162a73d75c43a7f90715832bd13_img.jpg) + +The diagram illustrates the ONT core architecture, centered around the **GEM Port Network CTP**. The components and their relationships are as follows: + +- Software Image**: Connected to **ONT Data** (1:1), **ONT-G** (1:1), and **ONT2-G** (1:2). +- ONT Data**: Connected to **ONT-G** (1:1). +- ONT-G**: The central gateway component, connected to **Cardholder** (1:1.127), **ONT2-G** (1:1), **Port Mapping Package** (1:1), and **Equipment Extension Package** (1:0..n). +- ONT2-G**: Connected to **ONT-G** (1:1) and **Circuit Pack** (1:0.1). +- Cardholder**: Connected to **ONT-G** (1:1.127) and **Circuit Pack** (0.1:1). +- Port Mapping Package**: Connected to **ONT-G** (1:1) and **Circuit Pack** (0.1:1). +- Equipment Extension Package**: Connected to **ONT-G** (1:0..n) and **Circuit Pack** (0.1:1). +- Circuit Pack**: Shown in two locations. The left one connects to **ONT2-G** (1:0.1), **Cardholder** (0.1:1), **Port Mapping Package** (0.1:1), **Equipment Extension Package** (0.1:1), and **PPTP UNI** (1:1.255). The right one connects to **Cardholder** (1:0.1), **Port Mapping Package** (1:0.2), **Equipment Extension Package** (1:0.2), **Traffic Scheduler-G** (1:0.256), and **PON PTP** (1:1.255). +- PPTP UNI**: Connected to **Circuit Pack** (1:1.255) and **UNI-G** (1:1). +- UNI-G**: Connected to **PPTP UNI** (1:1). +- PON PTP**: Connected to **Circuit Pack** (1:1.255) and **ANI-G** (1:1). +- ANI-G**: Connected to **PON PTP** (1:1). +- GEM Port Network CTP**: The central processing unit, connected to **Priority Queue (upstream)** (0..n:1), **OR** (1:0..n), **GEM Traffic Descriptor** (0..n:1), **GEM Port PM History Data** (0.1:1), and receiving input from the **User Data ME complex**. +- Priority Queue (upstream)**: Connected to **GEM Port Network CTP** (0..n:1) and **OR** (1:0..n). +- OR** (top): An OR gate component receiving inputs from **Priority Queue (upstream)** (1:0..n) and **Priority Queue (Downstream)** (1:0..n), with outputs to **Traffic Scheduler-G** (0.256:0..n) and **T-CONT** (0.256:0..n). +- Priority Queue (Downstream)**: Connected to **GEM Port Network CTP** (0..n:1) and **OR** (1:0..n). +- Traffic Scheduler-G**: Connected to **OR** (0.256:0..n) and **Circuit Pack** (1:0.256). +- T-CONT**: Connected to **OR** (0.256:0..n) and **Circuit Pack** (1:0.256). +- GEM Traffic Descriptor**: Connected to **GEM Port Network CTP** (0..n:1). +- GEM Port PM History Data**: Connected to **GEM Port Network CTP** (0.1:1). +- User Data ME complex**: An external input to the **GEM Port Network CTP**. + +A complex block diagram of the ONT core showing various functional blocks and their interconnections with multiplicities. + +Figure 8.2.1-1 – ONT core + +![Diagram of 1+1 PON protection architecture showing Working Side and Protecting Side components and their interconnections.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg) + +The diagram illustrates the 1+1 PON protection architecture, divided into a **Working Side** and a **Protecting Side**. + +**Working Side Components and Connections:** + +- Traffic Scheduler-G**: Receives traffic from an **OR** node (1 input, 0..n outputs). It has 0..n outputs to a **Priority Queue (upstream)** and 0..1 outputs to a **T-CONT**. +- OR** node: Combines traffic from **Traffic Scheduler-G** (0..n outputs) and **T-CONT** (1 output). +- T-CONT**: Receives traffic from **Traffic Scheduler-G** (0..1 outputs) and sends traffic to the **OR** node (1 output). +- OR** node: Combines traffic from the first **OR** node (0..n outputs) and **GEM Port Network CTP** (1 output). +- GEM Port Network CTP**: Receives **Protected Traffic** and sends traffic to the second **OR** node (1 output). +- Circuit Pack**: Receives traffic from the second **OR** node (0..256 outputs) and sends traffic to **PON PTP** (1..255 outputs). +- PON PTP**: Receives traffic from **Circuit Pack** (1 output) and sends traffic to **ANI-G** (1 output). +- ANI-G**: Receives traffic from **PON PTP** (1 output) and is connected to **Protection Data**. + +**Protecting Side Components and Connections:** + +- Traffic Scheduler-G**: Receives traffic from a central box (When protection is activated...) and sends traffic to an **OR** node (1 output). +- OR** node: Combines traffic from **Traffic Scheduler-G** (1 output) and **T-CONT** (0..256 outputs). +- T-CONT**: Receives traffic from the central box and sends traffic to the **OR** node (1 output). +- Circuit Pack**: Receives traffic from the **OR** node (0..256 outputs) and sends traffic to **PON PTP** (1..255 outputs). +- PON PTP**: Receives traffic from **Circuit Pack** (1 output) and sends traffic to **ANI-G** (1 output). +- ANI-G**: Receives traffic from **PON PTP** (1 output) and is connected to **Protection Data**. + +**Central Control and Data Flow:** + +- A central box labeled **When protection is activated, pointers to T-CONTs and Schedulers are mapped from working side to protecting side** receives inputs from **Traffic Scheduler-G** (0..n) and **T-CONT** (0..n) on the working side and sends outputs to the corresponding components on the protecting side. +- Protection Data** is exchanged between the **ANI-G** units on both sides. + +Diagram of 1+1 PON protection architecture showing Working Side and Protecting Side components and their interconnections. + +Figure 8.2.1-2 – 1+1 PON protection + +![Diagram of 1:1 PON protection architecture showing Working Side and Protecting Side components and their interconnections.](c494cd874a082a97b50b3c4d3938f467_img.jpg) + +The diagram illustrates the 1:1 PON protection architecture, divided into a **Working Side** and a **Protecting Side**. + +**Working Side Components and Connections:** + +- Traffic Scheduler-G:** Receives traffic from an **OR** node (1 input, 0..n outputs). It has 0..n outputs to a **Priority Queue (upstream)** and 0..1 outputs to a **T-CONT**. +- OR Node:** Receives 0..n inputs from a **T-CONT** and 0..256 inputs from a **Circuit Pack**. It has 1 output to the **Traffic Scheduler-G** and 0..256 outputs to the **T-CONT**. +- T-CONT:** Receives 0..n inputs from the **Traffic Scheduler-G** and 0..n inputs from the **OR** node. It has 1 output to a **Circuit Pack**. +- Circuit Pack:** Receives 0..256 inputs from the **T-CONT** and 1..255 inputs from a **PON PTP**. It has 1 output to the **PON PTP**. +- PON PTP:** Receives 1..255 inputs from the **Circuit Pack** and 1 input from an **ANI-G**. It has 1 output to the **ANI-G**. +- ANI-G:** Receives 1 input from the **PON PTP** and is connected to **Protection Data**. +- GEM Port Network CTP:** Receives 1 input from the **OR** node and is labeled as receiving **Protected Traffic**. It has 1 output to the **Protection Data**. + +**Protecting Side Components and Connections:** + +- Traffic Scheduler-G:** Receives traffic from the **Protection Data** (0..n outputs) and an **OR** node (1 input, 0..n outputs). It has 0..1 outputs to a **Priority Queue (upstream)** and 0..n outputs to a **T-CONT**. +- OR Node:** Receives 0..n inputs from a **T-CONT** and 0..256 inputs from a **Circuit Pack**. It has 1 output to the **Traffic Scheduler-G** and 0..256 outputs to the **T-CONT**. +- T-CONT:** Receives 0..n inputs from the **Traffic Scheduler-G** and 0..n inputs from the **OR** node. It has 1 output to a **Circuit Pack**. +- Circuit Pack:** Receives 0..256 inputs from the **T-CONT** and 1..255 inputs from a **PON PTP**. It has 1 output to the **PON PTP**. +- PON PTP:** Receives 1..255 inputs from the **Circuit Pack** and 1 input from an **ANI-G**. It has 1 output to the **ANI-G**. +- ANI-G:** Receives 1 input from the **PON PTP** and is connected to **Protection Data**. +- GEM Port Network CTP:** Receives 1 input from the **OR** node and is labeled as receiving **Extra Traffic**. It has 1 output to the **Protection Data**. + +**Central Protection Logic:** + +- A central box contains the text: "When protection is activated, pointers to T-CONTs and Schedulers are mapped from working side to protecting side". +- This box receives inputs from the **Protection Data** (0..n) and the **OR** node on the Working Side (0..1). +- It sends outputs to the **Traffic Scheduler-G** on the Protecting Side (0..n) and the **OR** node on the Protecting Side (0..1). + +Diagram of 1:1 PON protection architecture showing Working Side and Protecting Side components and their interconnections. + +**Figure 8.2.1-3 – 1:1 PON protection** + +### 8.2.2 Layer 2 functions + +There are two major layer 2 functions available: MAC bridging and "802.1p mapping". MAC bridging is described in [IEEE 802.1D]. The bridge described by Figure 8.2.2-1 below has many features, and can be used to direct traffic based on MAC address (that is, true bridging) or on VLAN characteristics (using the VLAN filter feature). The mapping function describes the steering of traffic from one UNI-side entity to 1-8 ANI-side port-IDs, as shown in Figure 8.2.2-2 below. The mapper is equivalent to a MAC bridge with VLAN filters that only operate on the priority bits of the VLAN tags. + +![UML Class Diagram for MAC bridged LAN (Figure 8.2.2-1).](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +This UML class diagram illustrates the architecture of a MAC bridged LAN. The diagram shows various components and their relationships: + +- Ext. VLAN tag oper. config. data** and **VLAN tag oper. config. data** are associated with the text "Any ME to which VLAN tagging can be assigned". +- GEM Interworking TP** is a central component with multiple associations: + - Association with **MAC Bridge Port Config Data** (multiplicity 1 to 0..1). + - Association with **GEM port network CTP** (multiplicity 1 to 1). + - Association with **GAL Ethernet PM History Data** (multiplicity 0..1 to 1). + - Association with **GAL Ethernet Profile** (multiplicity 1 to 0..n). +- MAC Bridge Port Config Data** (top) is associated with: + - MAC Bridge Service Profile** (multiplicity 0..m to 0..1). + - Bridge PM History Data** (multiplicity 0..1 to 1). + - MAC Bridge Port Config Data** (bottom) (multiplicity 1 to 0..1). +- MAC Bridge Service Profile** is associated with: + - MAC Bridge Config Data** (multiplicity 1 to 0..p). + - MAC Bridge Port Config Data** (bottom) (multiplicity 1 to 0..1). +- MAC Bridge Port Config Data** (bottom) is associated with: + - PPTP Ethernet UNI** (multiplicity 1 to 0..1). + - Ethernet PM History Data 3** (multiplicity 0..1 to 1). + - Bridge Port Filter Preassign** (multiplicity 0..1 to 1). +- PPTP Ethernet UNI** is associated with: + - UNI** (multiplicity 1 to 1). + - Ethernet PM History Data 2** (multiplicity 0..1 to 1). + - Ethernet PM History Data** (multiplicity 0..1 to 1). + - Bridge Port Bridge Table** (multiplicity 1 to 0..1). +- Bridge Port Filter Preassign** is associated with: + - VLAN Tagging Filter** (multiplicity 1 to 1). + - Bridge Port Filter Table** (multiplicity 1 to 1). + - Bridge Port Bridge Table** (multiplicity 1 to 1). + - Bridge Port Designation** (multiplicity 1 to 1). +- Bridge Port Bridge Table** is associated with: + - Bridge Port Designation** (multiplicity 1 to 1). + - Bridge Port PM History Data** (multiplicity 1 to 1). + +UML Class Diagram for MAC bridged LAN (Figure 8.2.2-1). + +Figure 8.2.2-1 – MAC bridged LAN + +![Diagram of 802.1p mapper architecture showing components and their relationships.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +The diagram illustrates the architecture of an 802.1p mapper. At the top, two boxes labeled 'Ext. VLAN tag oper. config. data' and 'VLAN tag oper. config. data' point to a text label 'Any ME to which VLAN tagging can be assigned'. Below this, a box labeled 'GEM Interworking TP' is connected to a 'GEM port network CTP' (multiplicity 1) and has a dashed connection to 'GAL Ethernet PM History Data' (multiplicity 0..1 to 1). To its right is 'GAL Ethernet Profile' (multiplicity 0..n). Below 'GEM Interworking TP' is '802.1p Mapper Service Profile' (multiplicity 0..8), which has a dashed connection to 'Ethernet PM History Data 3' (multiplicity 0..1 to 1). Below that is 'PPTP Ethernet UNI' (multiplicity 0..1), which has dashed connections to 'UNI' (multiplicity 1), 'Ethernet PM History Data 2' (multiplicity 0..1 to 1), and 'Ethernet PM History Data' (multiplicity 0..1 to 1). + +Diagram of 802.1p mapper architecture showing components and their relationships. + +**Figure 8.2.2-2 – 802.1p mapper** + +These two basic layer 2 services can be used in various combinations to achieve different overall connectivities. There are three major functional styles of layer 2 connectivity, illustrated in Figures 8.2.2-3 to 8.2.2-5: + +- N:1 bridging, where a bridge is used to serve multiple UNI ports from a single ANI service. +- 1:M mapping, where a mapper is used to serve a single UNI with multiple ANI connections, based on 802.1p priorities. +- 1:P filtering, where a bridge with filters is used to serve a single UNI with multiple ANI connections, based on some VLAN information other than 802.1p priorities. + +Given these three basic possibilities, there are also four more complex combinations as well, illustrated in Figures 8.2.2-6 to 8.2.2-9. It is strongly encouraged that these applications be utilized before other, more exotic styles of usage. + +![UML class diagram illustrating N:1 bridging architecture. At the top is GEM Interworking TP. Below it is MAC Bridge Port Config Data (1 to 1 with GEM). Below that is MAC Bridge Service Profile (1 to 1 with Port Config Data, 1 to N with Port Config Data). Below the Service Profile are two MAC Bridge Port Config Data blocks (1 to N with Service Profile). Each Port Config Data block is associated with a VLAN tag oper. config. data (1 to 1), a PPTP Ethernet UNI (1 to 1), and a UNI (1 to 1 via dashed line).](7ae836e598020d937ed1478c2ef13025_img.jpg) + +``` + +classDiagram + GEM_Interworking_TP : "1" -- "1" MAC_Bridge_Port_Config_Data_1 : MAC Bridge Port Config Data + MAC_Bridge_Port_Config_Data_1 : "1" -- "1" MAC_Bridge_Service_Profile : MAC Bridge Service Profile + MAC_Bridge_Service_Profile : "1" -- "N" MAC_Bridge_Port_Config_Data_2 : MAC Bridge Port Config Data + MAC_Bridge_Port_Config_Data_2 : "1" -- "1" VLAN_tag_oper_config_data_1 : VLAN tag oper. config. data + MAC_Bridge_Port_Config_Data_2 : "1" -- "1" PPTP_Ethernet_UNI_1 : PPTP Ethernet UNI + MAC_Bridge_Port_Config_Data_2 : "1" -- "1" UNI_1 : UNI + MAC_Bridge_Port_Config_Data_3 : "1" -- "1" VLAN_tag_oper_config_data_2 : VLAN tag oper. config. data + MAC_Bridge_Port_Config_Data_3 : "1" -- "1" PPTP_Ethernet_UNI_2 : PPTP Ethernet UNI + MAC_Bridge_Port_Config_Data_3 : "1" -- "1" UNI_2 : UNI + +``` + +UML class diagram illustrating N:1 bridging architecture. At the top is GEM Interworking TP. Below it is MAC Bridge Port Config Data (1 to 1 with GEM). Below that is MAC Bridge Service Profile (1 to 1 with Port Config Data, 1 to N with Port Config Data). Below the Service Profile are two MAC Bridge Port Config Data blocks (1 to N with Service Profile). Each Port Config Data block is associated with a VLAN tag oper. config. data (1 to 1), a PPTP Ethernet UNI (1 to 1), and a UNI (1 to 1 via dashed line). + +Figure 8.2.2-3 – Illustration of N:1 bridging + +![Diagram illustrating 1:M mapping in a network architecture. It shows the flow of data from a UNI through a PPTP Ethernet UNI, an 802.1p Mapper Service Profile, and multiple GEM Interworking TP units to various GEM port network CTPs. The diagram includes cardinality labels like 1, M, and 1:M on the connections.](f9c64800d9bace9b4315646d1057be3c_img.jpg) + +``` + +graph TD + UNI[UNI] -.-> PPTP[PPTP Ethernet UNI] + PPTP -- 1 --> Mapper[802.1p Mapper Service Profile] + Config[VLAN tag oper. config. data] -- 1 --> Mapper + Mapper -- 1 --> GEM1[GEM Interworking TP] + Mapper -- M --> GEM2[GEM Interworking TP] + GEM1 -- 1 --> CTP1[GEM port network CTP] + GEM2 -- 1 --> CTP2[GEM port network CTP] + +``` + +The diagram illustrates a network architecture for 1:M mapping. At the bottom, a **UNI** (User Network Interface) is connected via a dashed line to a **PPTP Ethernet UNI**. This UNI is connected to an **802.1p Mapper Service Profile** with a cardinality of 1. The mapper also receives input from **VLAN tag oper. config. data** with a cardinality of 1. From the mapper, two arrows point to **GEM Interworking TP** units: one with a cardinality of 1 and another with a cardinality of M. Each GEM Interworking TP unit is then connected to a **GEM port network CTP** (Core Termination Point) with a cardinality of 1. + +Diagram illustrating 1:M mapping in a network architecture. It shows the flow of data from a UNI through a PPTP Ethernet UNI, an 802.1p Mapper Service Profile, and multiple GEM Interworking TP units to various GEM port network CTPs. The diagram includes cardinality labels like 1, M, and 1:M on the connections. + +Figure 8.2.2-4 – Illustration of 1:M mapping + +![A block diagram illustrating 1:P filtering. It shows the relationships between various network entities: VLAN Tagging Filter, GEM Interworking TP, MAC Bridge Port Config Data, MAC Bridge Service Profile, VLAN tag oper. config. data, PPTP Ethernet UNI, and UNI. Multiplicities like '1' and 'P' are indicated on the connecting lines.](e451401f8fa77b466f401d5fce15b26c_img.jpg) + +``` + +graph TD + VTF1[VLAN Tagging Filter] -. 1 .- MPD1[MAC Bridge Port Config Data] + VTF2[VLAN Tagging Filter] -. 1 .- MPD2[MAC Bridge Port Config Data] + GITP1[GEM Interworking TP] -- 1 -- MPD1 + GITP2[GEM Interworking TP] -- 1 -- MPD2 + MPD1 -- 1 -- MBSP[MAC Bridge Service Profile] + MPD2 -- 1 -- MBSP + GITP1 -- 1 -- MBSP + GITP2 -- 1 -- MBSP + MBSP -- 1 -- MPD3[MAC Bridge Port Config Data] + MPD3 -. 1 .- VTF3[VLAN Tagging Filter] + VTOCD[VLAN tag oper. config. data] -- 1 -- MPD3 + VTOCD -- 1 -- PPTP[PPTP Ethernet UNI] + MPD3 -- 1 -- PPTP + PPTP -. 1 .- UNI[UNI] + + %% Multiplicity P arrow + MPD1 -- P --> MBSP + MPD2 -- P --> MBSP + +``` + +A block diagram illustrating 1:P filtering. It shows the relationships between various network entities: VLAN Tagging Filter, GEM Interworking TP, MAC Bridge Port Config Data, MAC Bridge Service Profile, VLAN tag oper. config. data, PPTP Ethernet UNI, and UNI. Multiplicities like '1' and 'P' are indicated on the connecting lines. + +Figure 8.2.2-5 – Illustration of 1:P filtering + +![A block diagram illustrating N:M bridge-mapping. At the top, two 'GEM port network CTP' labels point to two 'GEM Interworking TP' blocks. The left 'GEM Interworking TP' has a '1' relationship with the top CTP, a '1' relationship with an '802.1p Mapper Service Profile' block, and an 'M' relationship with a 'MAC Bridge Service Profile' block. The right 'GEM Interworking TP' has a '1' relationship with its top CTP, a '1' relationship with the '802.1p Mapper Service Profile' block, and a '1' relationship with a 'MAC Bridge Port Config Data' block. The '802.1p Mapper Service Profile' block has a '1' relationship with the 'MAC Bridge Service Profile' block. The 'MAC Bridge Service Profile' block has an 'N' relationship with a 'MAC Bridge Port Config Data' block. There are two 'MAC Bridge Port Config Data' blocks. The left one has a '1' relationship with a 'VLAN tag oper. config. data' block, a '1' relationship with the 'MAC Bridge Service Profile' block, and a '1' relationship with a 'PPTP Ethernet UNI' block. The right one has a '1' relationship with another 'VLAN tag oper. config. data' block, a '1' relationship with the 'MAC Bridge Service Profile' block, and a '1' relationship with another 'PPTP Ethernet UNI' block. Each 'PPTP Ethernet UNI' block has a '1' relationship with a 'UNI' block at the bottom. Dashed lines connect each 'UNI' block to its corresponding 'PPTP Ethernet UNI' block.](f57c7b37d7a05a99618104f390089f03_img.jpg) + +``` + +graph TD + subgraph TopLeft [ ] + direction TB + CTP1[GEM port network CTP] -- 1 --> GI1[GEM Interworking TP] + end + subgraph TopRight [ ] + direction TB + CTP2[GEM port network CTP] -- 1 --> GI2[GEM Interworking TP] + end + GI1 -- 1 --> M8021p[802.1p Mapper Service Profile] + GI1 -- M --> MBSP[MAC Bridge Service Profile] + GI2 -- 1 --> M8021p + GI2 -- 1 --> MPD1[MAC Bridge Port Config Data] + M8021p -- 1 --> MBSP + MBSP -- N --> MPD2[MAC Bridge Port Config Data] + MPD1 -- 1 --> VTC1[VLAN tag oper. config. data] + MPD1 -- 1 --> MBSP + MPD1 -- 1 --> PE1[PPTP Ethernet UNI] + MPD2 -- 1 --> VTC2[VLAN tag oper. config. data] + MPD2 -- 1 --> MBSP + MPD2 -- 1 --> PE2[PPTP Ethernet UNI] + PE1 -- 1 --> UNI1[UNI] + PE2 -- 1 --> UNI2[UNI] + UNI1 -.-> PE1 + UNI2 -.-> PE2 + style TopLeft fill:none,stroke:none + style TopRight fill:none,stroke:none + +``` + +A block diagram illustrating N:M bridge-mapping. At the top, two 'GEM port network CTP' labels point to two 'GEM Interworking TP' blocks. The left 'GEM Interworking TP' has a '1' relationship with the top CTP, a '1' relationship with an '802.1p Mapper Service Profile' block, and an 'M' relationship with a 'MAC Bridge Service Profile' block. The right 'GEM Interworking TP' has a '1' relationship with its top CTP, a '1' relationship with the '802.1p Mapper Service Profile' block, and a '1' relationship with a 'MAC Bridge Port Config Data' block. The '802.1p Mapper Service Profile' block has a '1' relationship with the 'MAC Bridge Service Profile' block. The 'MAC Bridge Service Profile' block has an 'N' relationship with a 'MAC Bridge Port Config Data' block. There are two 'MAC Bridge Port Config Data' blocks. The left one has a '1' relationship with a 'VLAN tag oper. config. data' block, a '1' relationship with the 'MAC Bridge Service Profile' block, and a '1' relationship with a 'PPTP Ethernet UNI' block. The right one has a '1' relationship with another 'VLAN tag oper. config. data' block, a '1' relationship with the 'MAC Bridge Service Profile' block, and a '1' relationship with another 'PPTP Ethernet UNI' block. Each 'PPTP Ethernet UNI' block has a '1' relationship with a 'UNI' block at the bottom. Dashed lines connect each 'UNI' block to its corresponding 'PPTP Ethernet UNI' block. + +Figure 8.2.2-6 – Illustration of N:M bridge-mapping + +![A complex block diagram illustrating 1:MP map-filtering. It shows two parallel processing paths for GEM ports. Each path consists of a GEM port network CTP, a GEM Interworking TP, an 802.1p Mapper Service Profile, a MAC Bridge Port Config Data block, and a VLAN Tagging Filter. These components are interconnected with arrows indicating data flow and associations, with multiplicity labels like '1', 'M', and 'P'. The two paths converge at a central MAC Bridge Service Profile block, which is further connected to a MAC Bridge Port Config Data block, a VLAN tag oper. config. data block, a PPTP Ethernet UNI, and finally a UNI block at the bottom.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +The diagram illustrates the architecture for 1:MP map-filtering. At the top, four GEM port network CTPs are shown. Each is connected to a GEM Interworking TP (1:1 relationship). Each GEM Interworking TP is connected to an 802.1p Mapper Service Profile (1:M relationship) and a MAC Bridge Port Config Data block (1:1 relationship). Each 802.1p Mapper Service Profile is connected to a MAC Bridge Port Config Data block (1:1 relationship) and a VLAN Tagging Filter (1:1 relationship). The four MAC Bridge Port Config Data blocks are connected to a central MAC Bridge Service Profile block (1:P relationship). The central MAC Bridge Service Profile block is connected to a MAC Bridge Port Config Data block (1:1 relationship). This MAC Bridge Port Config Data block is connected to a VLAN tag oper. config. data block (1:1 relationship), a VLAN Tagging Filter (1:1 relationship), and a PPTP Ethernet UNI (1:1 relationship). The PPTP Ethernet UNI is connected to a UNI block (1:1 relationship). + +A complex block diagram illustrating 1:MP map-filtering. It shows two parallel processing paths for GEM ports. Each path consists of a GEM port network CTP, a GEM Interworking TP, an 802.1p Mapper Service Profile, a MAC Bridge Port Config Data block, and a VLAN Tagging Filter. These components are interconnected with arrows indicating data flow and associations, with multiplicity labels like '1', 'M', and 'P'. The two paths converge at a central MAC Bridge Service Profile block, which is further connected to a MAC Bridge Port Config Data block, a VLAN tag oper. config. data block, a PPTP Ethernet UNI, and finally a UNI block at the bottom. + +Figure 8.2.2-7 – Illustration of 1:MP map-filtering + +![UML Class Diagram illustrating N:P bridge-filtering architecture. The diagram shows a central MAC Bridge Service Profile connected to various components including GEM Interworking TP, MAC Bridge Port Config Data, VLAN Tagging Filter, VLAN tag oper. config. data, PPTP Ethernet UNI, and UNI. Multiplicity indicators like 1, P, N, and dashed lines are used to show relationships between these elements.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +``` + +classDiagram + class GEM_Interworking_TP [GEM Interworking TP] + class VLAN_Tagging_Filter_1 [VLAN Tagging Filter] + class MAC_Bridge_Port_Config_Data_1 [MAC Bridge Port Config Data] + class MAC_Bridge_Service_Profile [MAC Bridge Service Profile] + class MAC_Bridge_Port_Config_Data_2 [MAC Bridge Port Config Data] + class VLAN_tag_oper_config_data_1 [VLAN tag oper. config. data] + class VLAN_tag_oper_config_data_2 [VLAN tag oper. config. data] + class MAC_Bridge_Port_Config_Data_3 [MAC Bridge Port Config Data] + class VLAN_Tagging_Filter_2 [VLAN Tagging Filter] + class PPTP_Ethernet_UNI_1 [PPTP Ethernet UNI] + class PPTP_Ethernet_UNI_2 [PPTP Ethernet UNI] + class UNI_1 [UNI] + class UNI_2 [UNI] + + GEM_Interworking_TP "1" -- "1" MAC_Bridge_Service_Profile + GEM_Interworking_TP "1" -- "1" MAC_Bridge_Port_Config_Data_1 + GEM_Interworking_TP "1" -- "1" VLAN_Tagging_Filter_1 + MAC_Bridge_Service_Profile "1" -- "P" MAC_Bridge_Port_Config_Data_1 + MAC_Bridge_Service_Profile "1" -- "N" MAC_Bridge_Port_Config_Data_2 + MAC_Bridge_Service_Profile "1" -- "1" MAC_Bridge_Port_Config_Data_3 + MAC_Bridge_Port_Config_Data_1 "1" -- "1" VLAN_tag_oper_config_data_1 + MAC_Bridge_Port_Config_Data_1 "1" -- "1" PPTP_Ethernet_UNI_1 + MAC_Bridge_Port_Config_Data_2 "1" -- "1" VLAN_tag_oper_config_data_2 + MAC_Bridge_Port_Config_Data_2 "1" -- "1" PPTP_Ethernet_UNI_2 + MAC_Bridge_Port_Config_Data_3 "1" -- "1" VLAN_tag_oper_config_data_2 + MAC_Bridge_Port_Config_Data_3 "1" -- "1" VLAN_Tagging_Filter_2 + PPTP_Ethernet_UNI_1 "1" -- "1" UNI_1 + PPTP_Ethernet_UNI_2 "1" -- "1" UNI_2 + +``` + +UML Class Diagram illustrating N:P bridge-filtering architecture. The diagram shows a central MAC Bridge Service Profile connected to various components including GEM Interworking TP, MAC Bridge Port Config Data, VLAN Tagging Filter, VLAN tag oper. config. data, PPTP Ethernet UNI, and UNI. Multiplicity indicators like 1, P, N, and dashed lines are used to show relationships between these elements. + +Figure 8.2.2-8 – Illustration of N:P bridge-filtering + +![Figure 8.2.2-9 – Illustration of N:MP bridge-map-filtering. This is a complex block diagram showing the internal architecture of a bridge. At the top, four 'GEM port network CTP' labels point to four 'GEM Interworking TP' blocks. Each 'GEM Interworking TP' is connected to an '802.1p Mapper Service Profile' block. These mapper blocks are then connected to 'MAC Bridge Port Config Data' blocks. A central 'MAC Bridge Service Profile' block is connected to all four 'MAC Bridge Port Config Data' blocks. Below each 'MAC Bridge Port Config Data' block is a 'VLAN tag oper. config. data' block, which in turn connects to a 'PPTP Ethernet UNI' block. Each 'PPTP Ethernet UNI' block connects to a 'UNI' block at the bottom. There are also 'VLAN Tagging Filter' blocks connected to the 'MAC Bridge Port Config Data' blocks via dashed lines. Multiplicity indicators like '1', 'M', 'P', and 'N' are shown on the connection lines between various components.](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg) + +Figure 8.2.2-9 – Illustration of N:MP bridge-map-filtering. This is a complex block diagram showing the internal architecture of a bridge. At the top, four 'GEM port network CTP' labels point to four 'GEM Interworking TP' blocks. Each 'GEM Interworking TP' is connected to an '802.1p Mapper Service Profile' block. These mapper blocks are then connected to 'MAC Bridge Port Config Data' blocks. A central 'MAC Bridge Service Profile' block is connected to all four 'MAC Bridge Port Config Data' blocks. Below each 'MAC Bridge Port Config Data' block is a 'VLAN tag oper. config. data' block, which in turn connects to a 'PPTP Ethernet UNI' block. Each 'PPTP Ethernet UNI' block connects to a 'UNI' block at the bottom. There are also 'VLAN Tagging Filter' blocks connected to the 'MAC Bridge Port Config Data' blocks via dashed lines. Multiplicity indicators like '1', 'M', 'P', and 'N' are shown on the connection lines between various components. + +**Figure 8.2.2-9 – Illustration of N:MP bridge-map-filtering** + +Finally, Figure 8.2.2-10 illustrates the usage of the multicast interworking termination point. A bridge is used to multiplex the multiple ANI-side ports into the single (in this case) UNI-side port. It is essential to have a unicast path in parallel to the multicast path, because the unicast path carries the upstream signalling that is required for control of the multicast transmissions. In most scenarios, a unicast path already exists for other user communications. + +![UML Class Diagram illustrating multicast service components and their relationships.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +``` + +classDiagram + class GEM_Multicast_Interworking_TP + class MAC_Bridge_Port_Config_Data_1 [MAC Bridge Port Config Data] + class MAC_Bridge_Service_Profile + class MAC_Bridge_Port_Config_Data_2 [MAC Bridge Port Config Data] + class GEM_Interworking_TP + class VLAN_tag_oper_config_data [VLAN tag oper. config. data] + class MAC_Bridge_Port_Config_Data_3 [MAC Bridge Port Config Data] + class PPTP_Ethernet_UNI + class UNI + + GEM_Multicast_Interworking_TP "1" --> "1" MAC_Bridge_Port_Config_Data_1 + GEM_Multicast_Interworking_TP "1" --> "1" MAC_Bridge_Service_Profile + MAC_Bridge_Port_Config_Data_1 "1" --> "P" MAC_Bridge_Service_Profile + MAC_Bridge_Service_Profile "1" --> "1" MAC_Bridge_Port_Config_Data_2 + MAC_Bridge_Service_Profile "1" --> "1" MAC_Bridge_Port_Config_Data_3 + MAC_Bridge_Port_Config_Data_2 "1" --> "1" GEM_Interworking_TP + MAC_Bridge_Port_Config_Data_2 "1" --> "1" MAC_Bridge_Service_Profile + VLAN_tag_oper_config_data "1" --> "1" MAC_Bridge_Port_Config_Data_3 + MAC_Bridge_Port_Config_Data_3 "1" --> "1" PPTP_Ethernet_UNI + UNI "1" ..> "1" PPTP_Ethernet_UNI + +``` + +The diagram illustrates the relationships between various network components for multicast service. At the top, two boxes labeled 'GEM Multicast Interworking TP' and 'GEM Interworking TP' are shown. The 'GEM Multicast Interworking TP' box has a directed association (arrow) to a 'MAC Bridge Port Config Data' box (multiplicity 1) and another directed association to a 'MAC Bridge Service Profile' box (multiplicity 1). The 'MAC Bridge Port Config Data' box has a directed association to the 'MAC Bridge Service Profile' box (multiplicity P). The 'MAC Bridge Service Profile' box has directed associations to two 'MAC Bridge Port Config Data' boxes (multiplicity 1 each). The top 'MAC Bridge Port Config Data' box has a directed association to the 'GEM Interworking TP' box (multiplicity 1) and another directed association back to the 'MAC Bridge Service Profile' box (multiplicity 1). Below the bottom 'MAC Bridge Port Config Data' box is a 'VLAN tag oper. config. data' box with a directed association to it (multiplicity 1). Below the 'VLAN tag oper. config. data' box is a 'PPTP Ethernet UNI' box with a directed association to it (multiplicity 1). At the bottom is a 'UNI' box with a dashed directed association to the 'PPTP Ethernet UNI' box (multiplicity 1). + +UML Class Diagram illustrating multicast service components and their relationships. + +**Figure 8.2.2-10 – Illustration of multicast service** + +### 8.2.3 Routing + +![UML Class Diagram for IP routing](4ae4505e885586e481a3ad3bff5198b7_img.jpg) + +This UML class diagram illustrates the IP routing architecture. The central component is the **GEM Interworking TP** (Traffic Path), which is associated with **Ext. VLAN tag oper. config. data** and **VLAN tag oper. config. data**. A note indicates that "Any ME to which VLAN tagging can be assigned" is linked to these VLAN configuration classes. The **GEM Interworking TP** is also connected to **GEM port network CTP**, **GAL Ethernet PM History Data**, **GAL Ethernet Profile**, **IP Port Config Data**, and **IP Router Service Profile**. The **IP Router Service Profile** is linked to **IP Router PM History Data 1**, **IP Router PM History Data 2**, **ICMP PM History Data 1**, **ICMP PM History Data 2**, **IP Router Config Data**, **IP Route Table**, **IP Static Routes**, and **IP Port Config Data**. The **IP Port Config Data** is connected to **ARP Service Profile**, **ARP Config Data**, and **PPTP Ethernet UNI**. The **PPTP Ethernet UNI** is linked to **UNI**, **Ethernet PM History Data 2**, **Ethernet PM History Data 3**, and **Ethernet PM History Data**. + +``` + +classDiagram + class Ext_VLAN_tag_oper_config_data["Ext. VLAN tag oper. config. data"] + class VLAN_tag_oper_config_data["VLAN tag oper. config. data"] + class GEM_Interworking_TP["GEM Interworking TP"] + class GEM_port_network_CTP["GEM port network CTP"] + class GAL_Ethernet_PM_History_Data["GAL Ethernet PM History Data"] + class GAL_Ethernet_Profile["GAL Ethernet Profile"] + class IP_Router_PM_History_Data_1["IP Router PM History Data 1"] + class IP_Router_PM_History_Data_2["IP Router PM History Data 2"] + class ICMP_PM_History_Data_1["ICMP PM History Data 1"] + class ICMP_PM_History_Data_2["ICMP PM History Data 2"] + class IP_Router_Service_Profile["IP Router Service Profile"] + class IP_Router_Config_Data["IP Router Config Data"] + class IP_Route_Table["IP Route Table"] + class IP_Static_Routes["IP Static Routes"] + class IP_Port_Config_Data_1["IP Port Config Data"] + class ARP_Service_Profile["ARP Service Profile"] + class ARP_Config_Data["ARP Config Data"] + class PPTP_Ethernet_UNI["PPTP Ethernet UNI"] + class UNI["UNI"] + class Ethernet_PM_History_Data_2["Ethernet PM History Data 2"] + class Ethernet_PM_History_Data_3["Ethernet PM History Data 3"] + class Ethernet_PM_History_Data["Ethernet PM History Data"] + + Ext_VLAN_tag_oper_config_data --> GEM_Interworking_TP + VLAN_tag_oper_config_data --> GEM_Interworking_TP + GEM_Interworking_TP --> GEM_port_network_CTP + GEM_Interworking_TP --> GAL_Ethernet_PM_History_Data + GEM_Interworking_TP --> GAL_Ethernet_Profile + GEM_Interworking_TP --> IP_Router_Service_Profile + GEM_Interworking_TP --> IP_Port_Config_Data_1 + IP_Router_Service_Profile --> IP_Router_PM_History_Data_1 + IP_Router_Service_Profile --> IP_Router_PM_History_Data_2 + IP_Router_Service_Profile --> ICMP_PM_History_Data_1 + IP_Router_Service_Profile --> ICMP_PM_History_Data_2 + IP_Router_Service_Profile --> IP_Router_Config_Data + IP_Router_Service_Profile --> IP_Route_Table + IP_Router_Service_Profile --> IP_Static_Routes + IP_Router_Service_Profile --> IP_Port_Config_Data_1 + IP_Port_Config_Data_1 --> ARP_Service_Profile + IP_Port_Config_Data_1 --> ARP_Config_Data + IP_Port_Config_Data_1 --> PPTP_Ethernet_UNI + PPTP_Ethernet_UNI --> UNI + PPTP_Ethernet_UNI --> Ethernet_PM_History_Data_2 + PPTP_Ethernet_UNI --> Ethernet_PM_History_Data_3 + PPTP_Ethernet_UNI --> Ethernet_PM_History_Data + +``` + +UML Class Diagram for IP routing + +Figure 8.2.3-1 – IP routing + +#### 8.2.4 xDSL service + +![](bb4d2112ed07e2031c92fbff3494af9f_img.jpg) + +``` + + graph TD + L2ME[from layer 2 ME +802.1p mapper or +MAC bridge port +configuration data +or VP Network +CTP-G] -- 1 --- PPTP1[PPTP xDSL +UNI Part 1] + PPTP1 -- 0..256 --- PPTP1 + PPTP1 -- 0..q --- SubMaskDown[xDSL +Subcarrier +Mask Down] + PPTP1 -- 1 --- SubMaskDown + PPTP1 -- 0..s --- PSDMask[xDSL +Downstream +PSD mask] + PPTP1 -- 0..r --- RFIBands[xDSL +Downstream +RFI Bands] + PPTP1 -- 1 --- RFIBands + PPTP1 -- 1 --- UNI[UNI] + PPTP1 -- 1 --- SubMaskUp[xDSL +Subcarrier +Mask Up] + PPTP1 -- 0..p --- SubMaskUp + + UNI -- 0..1 --- TCAdaptor((TC Adaptor +PM History +Data xDSL)) + UNI -- 1 --- PPTP2[PPTP xDSL +UNI Part 2] + + PPTP2 -- 1..4 --- ChanDownStatus[xDSL chan. +downstream +Status] + ChanDownStatus -- 0..1 --- ChanPMHistoryR((xDSL xTU-R +Channel PM +History Data)) + + PPTP2 -- 8 --- ChanConfigProfile[xDSL Chan. +Config +Profile] + ChanConfigProfile -- 0..n --- ChanConfigProfile + + PPTP2 -- 1..4 --- ChanUpStatus[xDSL Chan. +upstream +Status] + ChanUpStatus -- 0..1 --- ChanPMHistoryC((xDSL xTU-C +Channel PM +History Data)) + + PPTP2 -- 1 --- LineConfig1[xDSL Line +Config Part +1] + + LineConfig1 -- 1 --- VDSL2Inv1[VDSL2 Line +Inventory and +Status Part 1] + LineConfig1 -- 1 --- VDSL2Ext[VDSL2 line +configuration +extensions] + LineConfig1 -- 1 --- LineConfig2[xDSL Line +Config Part +2] + + VDSL2Inv1 -- 1 --- VDSL2Inv2[VDSL2 Line +Inventory and +Status Part 2] + + VDSL2Ext -- 1 --- LineInv1[xDSL Line +Inventory and +Status Part 1] + LineInv1 -- 0..1 --- LinePMHistoryR((xDSL xTU-R +PM History +Data)) + + LineConfig2 -- 1 --- LineConfig3[xDSL Line +Config Part +3] + LineConfig2 -- 1 --- LineInv2[xDSL Line +Inventory and +Status Part 2] + + VDSL2Inv2 -- 1 --- VDSL2Inv3[VDSL2 Line +Inventory and +Status Part 3] + + LineConfig3 -- 1 --- LineInv3[xDSL Line +Inventory and +Status Part 3] + LineInv3 -- 0..1 --- LinePMHistoryC((xDSL xTU-C +PM History +Data)) + + LineInv2 -- 1 --- LineInv4[xDSL Line +Inventory and +Status Part 4] + +``` + +**Figure 8.2.4-1 – xDSL** + +Rec. ITU-T G.984.4 (02/2008)     37 + +![Diagram of ATM interworking for xDSL showing connections between layer 2 ME, VP Network CTP-G, Interworking VCC TP, AAL5 Profile, and AAL5 PM History Data.](cbb2d311b20781a595488445ded48d0a_img.jpg) + +Diagram illustrating ATM interworking for xDSL. The central component is the **VP Network CTP-G**, which is connected to **Interworking VCC TP** (multiplicity 0..n to 1). The **Interworking VCC TP** is connected to **AAL5 Profile** (multiplicity 0..n to 1) and **AAL5 PM History Data** (multiplicity 0..1 to 1). The **VP Network CTP-G** is also connected to **VP PM History Data** (multiplicity 1 to 0..1) and has an output labeled **0..256**. Above the **VP Network CTP-G**, there is a connection from **layer 2 ME (802.1p mapper or MAC bridge port configuration data)** (multiplicity 1 to 0..1). A note below the diagram states: **PPTP xDSL UNI Part 1 Note: individual bearer channels accessible via 2 MSBs of PPTP ME id**. + +Diagram of ATM interworking for xDSL showing connections between layer 2 ME, VP Network CTP-G, Interworking VCC TP, AAL5 Profile, and AAL5 PM History Data. + +Figure 8.2.4-2 – ATM interworking for xDSL + +### 8.2.5 802.11 service + +![Diagram of 802.11 wireless LAN showing connections between UNI, PPTP 802.11 UNI, 802.11 Sta Management Data 1, 802.11 Sta Management Data 2, 802.11 PHY FHSS DSSS IR Tables, 802.11 PM History Data, 802.11 General Purpose, and 802.11 MAC&PHY Antenna Data.](32ff77da4286b58c4778033acaa10836_img.jpg) + +Diagram illustrating 802.11 wireless LAN. The central component is the **PPTP 802.11 UNI**, which is connected to **UNI** (multiplicity 1 to 1) and **802.11 PM History Data** (multiplicity 1 to 0..1). The **PPTP 802.11 UNI** is also connected to **802.11 Sta Management Data 1** (multiplicity 1 to 1) and **802.11 General Purpose** (multiplicity 2..n to 1). The **802.11 Sta Management Data 1** is connected to **802.11 Sta Management Data 2** (multiplicity 1 to 1). The **802.11 Sta Management Data 2** is connected to **802.11 PHY FHSS DSSS IR Tables** (multiplicity 1 to 1) and **802.11 MAC&PHY Antenna Data** (multiplicity 1 to 1). The **802.11 PHY FHSS DSSS IR Tables** is connected to **802.11 MAC&PHY Antenna Data** (multiplicity 1 to 1). Above the **PPTP 802.11 UNI**, there is a connection from **layer 2 ME (802.1p mapper or MAC bridge port configuration data)** (multiplicity 1 to 0..1). + +Diagram of 802.11 wireless LAN showing connections between UNI, PPTP 802.11 UNI, 802.11 Sta Management Data 1, 802.11 Sta Management Data 2, 802.11 PHY FHSS DSSS IR Tables, 802.11 PM History Data, 802.11 General Purpose, and 802.11 MAC&PHY Antenna Data. + +Figure 8.2.5-1 – 802.11 wireless LAN + +### 8.2.6 MoCA service + +![Diagram of MoCA service architecture showing connections between MoCA Interface PM History Data, MoCA Ethernet PM History Data, PPTP MoCA UNI, and UNI.](878d9539700bd792e7d12ad6f1203c5d_img.jpg) + +This diagram illustrates the MoCA service architecture. At the top, an external source labeled "from layer 2 ME (802.1p mapper or MAC bridge port configuration data)" provides configuration data to a central block labeled "PPTP MoCA UNI". This connection is marked with a "1" at the source and "0..1" at the UNI. To the left of the PPTP MoCA UNI are two data blocks: "MoCA Interface PM History Data" and "MoCA Ethernet PM History Data". Both are connected to the PPTP MoCA UNI via dashed lines, with a "1" at each data block and a "1" at the UNI side. To the right of the PPTP MoCA UNI is a block labeled "UNI", which is also connected via a dashed line with a "1" at the UNI side and a "0..1" at the PPTP MoCA UNI side. + +Diagram of MoCA service architecture showing connections between MoCA Interface PM History Data, MoCA Ethernet PM History Data, PPTP MoCA UNI, and UNI. + +Figure 8.2.6-1 – Multimedia over Coax Alliance (MoCA) + +### 8.2.7 Video return path + +![Diagram of Video return path architecture showing connections between GEM port network CTP, GEM Interworking TP, GAL Ethernet PM History Data, GAL Ethernet Profile, VRP Service Profile, PPTP Video ANI, PPTP Video UNI, and VRP PM History Data.](f142b022cfc716cd967297f027efe647_img.jpg) + +This diagram illustrates the Video return path architecture. At the top, a "GEM port network CTP" is connected to a "GEM Interworking TP" block via a solid line with a "1" at the CTP and a "1" at the TP. The GEM Interworking TP is connected to three other components: "GAL Ethernet PM History Data" (dashed line, "0..1" at TP, "1" at GAL), "GAL Ethernet Profile" (solid line, "1" at TP, "0..n" at GAL), and "VRP Service Profile" (solid line, "1" at TP, "0..1" at VRP). The VRP Service Profile is connected to "PPTP Video ANI" (dashed line, "1..n" at VRP, "1..n" at ANI) and "PPTP Video UNI" (dashed line, "1" at VRP, "1" at UNI). The PPTP Video ANI is also connected to the PPTP Video UNI (dashed line, "1" at ANI, "1" at UNI). Finally, the PPTP Video UNI is connected to "VRP PM History Data" (dashed line, "0..1" at UNI, "1" at VRP). + +Diagram of Video return path architecture showing connections between GEM port network CTP, GEM Interworking TP, GAL Ethernet PM History Data, GAL Ethernet Profile, VRP Service Profile, PPTP Video ANI, PPTP Video UNI, and VRP PM History Data. + +Figure 8.2.7-1 – Video return path + +### 8.2.8 VoIP service + +![UML Class Diagram for SIP VoIP service](6cc85a2b62fd8a2a3faab29730f20e81_img.jpg) + +``` + +classDiagram + class VoIPConfigData + class SIPAgentPMHistoryData + class SIPCallInitiationPMHistoryData + class SIPConfigPortal + + VoIPConfigData "1" -- "1" SIPConfigPortal + SIPAgentPMHistoryData "1" -- "0..1" SIPConfigPortal + SIPCallInitiationPMHistoryData "1" -- "0..1" SIPConfigPortal + +``` + +The diagram shows a central class 'SIP Config Portal' connected to three other classes. 'VoIP Config Data' is connected to 'SIP Config Portal' with a multiplicity of 1 at both ends. 'SIP Agent PM History Data' is connected to 'SIP Config Portal' with a multiplicity of 1 at the 'SIP Agent PM History Data' end and 0..1 at the 'SIP Config Portal' end. 'SIP Call Initiation PM History Data' is connected to 'SIP Config Portal' with a multiplicity of 1 at the 'SIP Call Initiation PM History Data' end and 0..1 at the 'SIP Config Portal' end. + +UML Class Diagram for SIP VoIP service + +\* Note: Any ME that require a large character string can reference a large string ME.. + +Note: Any ME that require a Network address can reference a Network Address ME. + +![UML Class Diagram for PPTP POTS UNI service](a161a2bbb4d830e847ccb4f44b7e41a9_img.jpg) + +``` + +classDiagram + class CallControlPMHistoryData + class RTPPMHistoryData + class PPTPPOTSUNI + class VoIPLineStatus + class UNI + + CallControlPMHistoryData "1" -- "0..1" PPTPPOTSUNI + RTPPMHistoryData "1" -- "0..1" PPTPPOTSUNI + PPTPPOTSUNI "1" -- "0..1" VoIPLineStatus + PPTPPOTSUNI "1" -- "1" UNI + +``` + +The diagram shows a central class 'PPTP POTS UNI' connected to four other classes. 'Call Control PM History Data' is connected to 'PPTP POTS UNI' with a multiplicity of 1 at the 'Call Control PM History Data' end and 0..1 at the 'PPTP POTS UNI' end. 'RTP PM History Data' is connected to 'PPTP POTS UNI' with a multiplicity of 1 at the 'RTP PM History Data' end and 0..1 at the 'PPTP POTS UNI' end. 'VoIP Line Status' is connected to 'PPTP POTS UNI' with a multiplicity of 1 at the 'VoIP Line Status' end and 0..1 at the 'PPTP POTS UNI' end. 'UNI' is connected to 'PPTP POTS UNI' with a multiplicity of 1 at both ends. + +UML Class Diagram for PPTP POTS UNI service + +Figure 8.2.8-1 – IP-path managed SIP VoIP + +![UML Class Diagram showing relationships between VoIP Config Data, MGC PM History Data, and MGC Config Portal.](c1df61cc3717e878a48e530218403403_img.jpg) + +``` + +classDiagram + class VoIPConfigData["VoIP Config Data"] + class MGCPMHistoryData["MGC PM History Data"] + class MGCConfigPortal["MGC Config Portal"] + + VoIPConfigData "1" -- "1" MGCConfigPortal + MGCPMHistoryData "1" -- "0..1" MGCConfigPortal + +``` + +UML Class Diagram showing relationships between VoIP Config Data, MGC PM History Data, and MGC Config Portal. + +\* Note: Any ME that requires a large character string can reference a large string ME.. + +Note: Any ME that requires a network address can reference a Network Address ME. + +![UML Class Diagram showing relationships between Call Control PM History Data, RTP PM History Data, PPTP POTS UNI, VoIP Line Status, and UNI.](be3e5fe8be7cc5a74f67a4b8ac93193d_img.jpg) + +``` + +class CallControlPMHistoryData["Call Control PM History Data"] +class RTPPMHistoryData["RTP PM History Data"] +class PPTPPOTSUNI["PPTP POTS UNI"] +class VoIPLineStatus["VoIP Line Status"] +class UNI + + CallControlPMHistoryData "1" -- "0..1" PPTPPOTSUNI + RTPPMHistoryData "1" -- "0..1" PPTPPOTSUNI + PPTPPOTSUNI "0..1" -- "1" VoIPLineStatus + PPTPPOTSUNI "0..1" -- "1" UNI + +``` + +UML Class Diagram showing relationships between Call Control PM History Data, RTP PM History Data, PPTP POTS UNI, VoIP Line Status, and UNI. + +**Figure 8.2.8-2 – IP path managed H.248 VoIP** + +![UML Class Diagram for OMCI managed SIP VoIP. The diagram shows various Management Entities (MEs) and their relationships. Central to the diagram is 'SIP User Data', which is associated with 'VoIP Voice CTP', 'SIP Agent Data', 'VoIP App Service Profile', 'Authentication Security Method', 'VoIP Feature Acc Codes', and 'Network Dial Plan Table'. 'VoIP Voice CTP' is linked to 'VoIP Media Profile', 'PPTP POTS UNI', and 'VoIP Line Status'. 'SIP Agent Data' is linked to 'SIP Agent PM History Data', 'TCP/UDP Config Data', and 'SIP Call Initiation PM History Data'. Other entities include 'RTP Profile', 'Voice Service Profile AAL', 'VoIP Config Data', 'RTP PM History Data', 'Call Control PM History Data', and 'UNI'. Multiplicity indicators like 0..m, 1, 0..1, and 1 are shown on the association lines.](38cbce07f83fba6d5a7c46605bd5743f_img.jpg) + +UML Class Diagram for OMCI managed SIP VoIP. The diagram shows various Management Entities (MEs) and their relationships. Central to the diagram is 'SIP User Data', which is associated with 'VoIP Voice CTP', 'SIP Agent Data', 'VoIP App Service Profile', 'Authentication Security Method', 'VoIP Feature Acc Codes', and 'Network Dial Plan Table'. 'VoIP Voice CTP' is linked to 'VoIP Media Profile', 'PPTP POTS UNI', and 'VoIP Line Status'. 'SIP Agent Data' is linked to 'SIP Agent PM History Data', 'TCP/UDP Config Data', and 'SIP Call Initiation PM History Data'. Other entities include 'RTP Profile', 'Voice Service Profile AAL', 'VoIP Config Data', 'RTP PM History Data', 'Call Control PM History Data', and 'UNI'. Multiplicity indicators like 0..m, 1, 0..1, and 1 are shown on the association lines. + +\* Note: Any ME that require a large character string can reference a large string ME.. + +Note: Any ME that require a Network address can reference a Network Address ME. + +**Figure 8.2.8-3 – OMCI managed SIP VoIP** + +![UML Class Diagram for OMCI managed H.248 VoIP. The diagram shows the following classes and their relationships: RTP Profile (0..m to 1 on VoIP Media Profile); Voice Service Profile AAL (1 to 1 on VoIP Media Profile); VoIP Media Profile (0..m to 1 on VoIP Voice CTP); VoIP Config Data; VoIP Line Status (1 to 0..1 on VoIP Voice CTP); RTP Monitoring Data (1 to 0..1 on PTP POTS UNI); Call Control PM History Data (1 to 0..1 on PTP POTS UNI); PTP POTS UNI (1 to 1 on UNI); UNI; MGC Config Data (0..1 to 1 on VoIP Voice CTP, 1 to 0..1 on TCP/UDP Config Data, 1 to 0..1 on MGC Monitoring Data); TCP/UDP Config Data; MGC Monitoring Data.](12c19090355e19922e23044633b9d1ea_img.jpg) + +``` + +classDiagram + class RTP_Profile [RTP Profile] + class Voice_Service_Profile_AAL [Voice Service Profile AAL] + class VoIP_Media_Profile [VoIP Media Profile] + class VoIP_Voice_CTP [VoIP Voice CTP] + class VoIP_Config_Data [VoIP Config Data] + class VoIP_Line_Status [VoIP Line Status] + class RTP_Monitoring_Data {RTP Monitoring Data} + class Call_Control_PM_History_Data {Call Control PM History Data} + class PTP_POTS_UNI [PTP POTS UNI] + class UNI + class MGC_Config_Data [MGC Config Data] + class TCP_UDP_Config_Data [TCP/UDP Config Data] + class MGC_Monitoring_Data {MGC Monitoring Data} + + RTP_Profile "0..m" -- "1" VoIP_Media_Profile + Voice_Service_Profile_AAL "1" -- "1" VoIP_Media_Profile + VoIP_Media_Profile "0..m" -- "1" VoIP_Voice_CTP + VoIP_Voice_CTP "1" -- "0..1" VoIP_Line_Status + VoIP_Voice_CTP "1" -- "0..m" MGC_Config_Data + VoIP_Voice_CTP "1" -- "1" PTP_POTS_UNI + PTP_POTS_UNI "1" -- "0..1" RTP_Monitoring_Data + PTP_POTS_UNI "1" -- "0..1" Call_Control_PM_History_Data + PTP_POTS_UNI "1" -- "1" UNI + MGC_Config_Data "0..1" -- "1" TCP_UDP_Config_Data + MGC_Config_Data "0..1" -- "1" MGC_Monitoring_Data + +``` + +UML Class Diagram for OMCI managed H.248 VoIP. The diagram shows the following classes and their relationships: RTP Profile (0..m to 1 on VoIP Media Profile); Voice Service Profile AAL (1 to 1 on VoIP Media Profile); VoIP Media Profile (0..m to 1 on VoIP Voice CTP); VoIP Config Data; VoIP Line Status (1 to 0..1 on VoIP Voice CTP); RTP Monitoring Data (1 to 0..1 on PTP POTS UNI); Call Control PM History Data (1 to 0..1 on PTP POTS UNI); PTP POTS UNI (1 to 1 on UNI); UNI; MGC Config Data (0..1 to 1 on VoIP Voice CTP, 1 to 0..1 on TCP/UDP Config Data, 1 to 0..1 on MGC Monitoring Data); TCP/UDP Config Data; MGC Monitoring Data. + +Note: Any ME that requires a large character string can reference a large string ME.. + +Note: Any ME that requires a network address can reference a Network Address ME. + +**Figure 8.2.8-4 – OMCI managed H.248 VoIP** + +![UML Class Diagram showing Common IP services. The diagram includes classes for Network Address, Authentication Security Method, Large string, IP host config data, TCP/UDP Config data, and IP host monitoring data. Associations show relationships between these classes with multiplicities.](5ee1bbbf85b473f78af9ec8368a4159a_img.jpg) + +``` + +classDiagram + direction TB + class NetworkAddress["Network Address"] + class AuthenticationSecurityMethod["Authentication Security Method"] + class LargeString["Large string"] + class IPHostConfigData["IP host config data"] + class TCPUDPConfigData["TCP/UDP Config data"] + class IPHostMonitoringData["IP host monitoring data"] + + AnyME["Any ME that requires +a network address"] --|> NetworkAddress + Layer2ME["from layer 2 ME +(802.1p mapper or +MAC bridge port +configuration data)"] --|> IPHostConfigData : 0..1 + + NetworkAddress "1" -- "1" AuthenticationSecurityMethod + NetworkAddress "1" -- "1" LargeString + IPHostConfigData "0..1" .. "1" IPHostMonitoringData + TCPUDPConfigData "1" -- "0..m" IPHostConfigData + +``` + +Any ME that requires +a network address + +from layer 2 ME +(802.1p mapper or +MAC bridge port +configuration data) + +UML Class Diagram showing Common IP services. The diagram includes classes for Network Address, Authentication Security Method, Large string, IP host config data, TCP/UDP Config data, and IP host monitoring data. Associations show relationships between these classes with multiplicities. + +**Figure 8.2.8-5 – Common IP services** + +### 8.2.9 Circuit emulation service + +![Diagram of Pseudowire TDM architecture showing various components and their relationships.](3d6f5edac3d5e7113d960c2202f1b0fa_img.jpg) + +The diagram illustrates the Pseudowire TDM architecture. At the top, an 'OR' node represents two transport options: 'Over IP' and 'Over Ethernet'. The 'Over IP' path connects to a 'TCP/UDP config data' block (multiplicity 1). The 'Over Ethernet' path connects to an 'Ethernet flow term. point' block (multiplicity 1), which in turn connects to an external source labeled 'from layer 2 ME (802.1p mapper or MAC bridge port configuration data)' (multiplicity 0..1). Both transport paths converge at a 'Pseudowire termination point' block (multiplicity 1). This central block is connected to several other components: a 'Pseudowire maintenance profile' block (multiplicity 1..n), an 'RTP pseudowire parameters' block (multiplicity 1), and a 'Pseudowire PM history data' block (multiplicity 0..1). Below the 'Pseudowire termination point', another 'OR' node represents 'Structured' and 'Unstructured' transport modes. The 'Structured' mode connects to a 'Logical Nx64 Sub-port CTP' block (multiplicity 1), which then connects to a 'PPTP CES UNI' block (multiplicity 1..n). The 'Unstructured' mode connects directly to the 'PPTP CES UNI' block (multiplicity 1). The 'PPTP CES UNI' block is also connected to a 'CES PHY PM History Data' block (multiplicity 1) and a 'UNI' block (multiplicity 1). Solid lines represent mandatory connections, while dashed lines represent optional connections. + +Diagram of Pseudowire TDM architecture showing various components and their relationships. + +Figure 8.2.9-1 – Pseudowire TDM + +![Diagram of SDH over GEM architecture showing relationships between GEM Interworking TP, TU termination point, Logical Nx64 Sub-port CTP, and PTP CES UNI.](2580688a4de0a29692805cc6ba4822d7_img.jpg) + +``` + +graph TD + GEM[\"GEM Interworking TP\"] -- \"1\" --> GEM_CTP[\"GEM port network CTP\"] + GEM -- \"0..1\" -.-> CES_GAL[\"CES GAL PM History Data\"] + GEM -- \"1\" --> TU[\"TU termination point\"] + GEM -- \"0..n\" --> CES_Profile[\"CES Profile\"] + TU -- \"1\" --> PTP_CES[\"PPTP CES UNI\"] + TU -- \"0..1\" -.-> TU_PM[\"TU PM history data\"] + TU -- \"1\" --> OR((OR)) + OR -- \"Structured\" --> Logical[\"Logical Nx64 Sub-port CTP\"] + OR -- \"Unstructured\" --> PTP_CES + Logical -- \"1\" --> PTP_CES + PTP_CES -- \"1\" -.-> CES_PHY[\"CES PHY PM History Data\"] + PTP_CES -- \"1\" --> UNI[\"UNI\"] + PW[\"Pseudowire maintenance profile\"] -- \"1..n\" --> TU + +``` + +The diagram illustrates the SDH over GEM architecture. At the top, the GEM Interworking TP is connected to a GEM port network CTP (1:1 relationship). It also has a dashed relationship with CES GAL PM History Data (0..1 to 1). Below the GEM Interworking TP is the TU termination point, connected via a 1:1 relationship. The TU termination point is associated with Pseudowire maintenance profile (1..n to 1), CES Profile (0..n to 1), and TU PM history data (0..1 to 1). Below the TU termination point is an OR node. The OR node has two paths: 'Structured' leading to Logical Nx64 Sub-port CTP and 'Unstructured' leading to PTP CES UNI. The Logical Nx64 Sub-port CTP is connected to the PTP CES UNI (1:1 relationship). The PTP CES UNI is connected to UNI (1:1 relationship) and has a dashed relationship with CES PHY PM History Data (1 to 1). + +Diagram of SDH over GEM architecture showing relationships between GEM Interworking TP, TU termination point, Logical Nx64 Sub-port CTP, and PTP CES UNI. + +Figure 8.2.9-2 – SDH over GEM + +# 9 MIB description + +This clause defines all ONT managed entities (MEs) of interest to G-PON. Code points for a number of managed entities are permanently reserved for B-PON legacy implementations; these managed entities remain available for use in G-PON if needed, but their definitions appear only in [ITU-T G.983.2], rather than below. In a few cases, managed entities that were specifically defined for G-PON have proven to be of little interest. As with B-PON MEs, their code points are permanently reserved for backward compatibility, but in the interest of brevity, their definitions have been omitted from this revision of this Recommendation. + +Managed entity (ME) descriptions include: + +- The purpose of the entity. +- The relationships that the entity supports with other managed entities. +- The attributes of the entity. +- The management operations (actions) that may be performed on the entity. Actions such as create, delete, get, get next, set and get current data are generic and are merely listed in the description of a given ME. Other actions are described in more detail. + +- e) The notifications generated by the managed entity. These may be attribute value changes (AVCs), alarms or performance monitoring threshold crossing alerts. Tables define each of these three classes as needed for each ME type. + +These clauses are organized as follows: + +- 9.1 Equipment management +- 9.2 ANI management +- 9.3 Layer 2 data services +- 9.4 Layer 3 data services +- 9.5 Ethernet services +- 9.6 802.11 services +- 9.7 xDSL services +- 9.8 TDM services +- 9.9 Voice services +- 9.10 MoCA +- 9.11 Traffic management +- 9.12 General purpose MEs +- 9.13 Miscellaneous services + +A managed entity can be instantiated by the ONT autonomously or on explicit request of the OLT via a create command. Attributes of a managed entity for which no create action exists (i.e., a managed entity that is auto-instantiated by the ONT) can be (R), (W) or (R, W). + +On the other hand, attributes of a managed entity for which a create action exists (i.e., a managed entity that is instantiated on explicit request by the OLT) can be either (R), (W), (R, W), (R, Set-by-create), (W, Set-by-create) or (R, W, Set-by-create). Where appropriate, this Recommendation specifies a default value, to be assigned to the attribute on instantiation of the managed entity. + +The following explains each case in more detail: + +- (R): On instantiation of the managed entity, either autonomously or on request of the OLT via a create action, the ONT sets the attribute to a default value or to a value that reflects a current state or measurement. The OLT can only read the value of the attribute. In case of an autonomous attribute value change, the ONT may send an attribute value change notification (AVC) to the OLT. +- (W): On instantiation of the managed entity, either autonomously or on request of the OLT via a create action, an initial value may or may not be specified. The OLT can only write the value of the attribute. Such an attribute never triggers an AVC notification to the OLT. +- (R, W): On instantiation of the managed entity, either autonomously or on request of the OLT via a create action, the ONT sets the attribute to a default value. The OLT can both read and write the value of the attribute. In case of an autonomous attribute value change, the ONT may send an AVC notification to the OLT. + +- (R, Set-by-create): On instantiation of the managed entity, by necessity on request of the OLT via a create action, the ONT sets the attribute to the value specified in the create command. Subsequently, the OLT cannot change the value of the attribute. This combination is used mostly for managed entity IDs, but occasionally for attributes that cannot meaningfully change after ME creation. +- (W, Set-by-create): On instantiation of the managed entity, by necessity on request of the OLT via a create action, the ONT sets the attribute to the value specified in the create command. Subsequently, the OLT can only write the value of the attribute. Such an attribute never triggers an AVC notification to the OLT. +- (R, W, Set-by-create): On instantiation of the managed entity, by necessity on request of the OLT via a create action, the ONT sets the attribute to the value specified in the create command. Subsequently, the OLT can both read and write the value of the attribute. In case of an autonomous attribute value change, the ONT may send an AVC notification to the OLT. In a number of cases, it is logically impossible to change (write) the value of an attribute after the ME is created. However, chicken and egg issues can arise when several such MEs point to each other. Allowing such attributes to be set after creation is intended to avoid these issues. + +The notifications generated by a managed entity stem from the following events: alarms, attribute value changes (AVCs), threshold crossing alerts (TCAs) and test results. + +Alarms, TCAs and failures of autonomous self tests are all reported via alarm messages. The alarm reporting message contains a field of 224 bits, which is mapped to as many as 208 specific alarms by the definition of each managed entity. The last 16 bits are reserved for vendor-specific alarms and are not to be standardized. Alarm bits are numbered from 0 upward. The general schema is illustrated in the following table, where each managed entity definition may specify some of the 208 reserved points for its own alarms. Different ME types can re-use the same codepoints because the alarm report message includes the ME type (and instance). + +**Generic alarm bit assignment** + +| Number | Alarm | Description | +|----------|------------------------|------------------------| +| 0..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +AVCs are reported via attribute value change messages. A managed entity can encompass not more than 16 attributes, exclusive of the ME ID, and the attribute change message contains a bit map of 16 bits that match attributes in order, starting with 1. If a managed entity can generate AVCs, its definition includes an AVC table that matches attributes with their corresponding bit numbers for easy reference. Attributes that do not trigger AVC notifications are shown as N/A, while bit positions for non-existent attributes are shown as reserved. + +Test results are reported: + +- via a test result message if the test is invoked by a test command from the OLT; or +- via an alarm message in the case of failure of an autonomous self test in the start-up phase; or +- via an autonomous test result message if a test failure is detected autonomously by the ONT. + +Details about these messages and their coding appear in Appendix II. + +## 9.1 Equipment management + +An ONT may be physically implemented as a single module (integrated ONT) or as a shelf containing plug-in field-replaceable units. The latter construction is technically called an ONU, but this Recommendation often uses the terms interchangeably to refer to either. Except for equipment-specific features, the same criteria pertain to both versions. + +An ONU with physical slots automatically instantiates cardholder MEs for each of its slots. A slot can then be populated with a circuit pack. Physical slots are recommended to number from left to right, then from bottom to top. + +An integrated ONT may or may not model itself with virtual cardholders and circuit packs. If not, the ONT itself is understood to exist in virtual slot 0, since a number of MEs use the slot id as part of their identifiers. + +When subscriber and PON-side physical ports are grouped into real or virtual circuit packs, each of which supports only a single type of interface, the port numbering algorithm is clear. An integrated ONT may choose not to model itself with virtual cardholders, and a complex circuit pack may have ports of several types, for example a PON ANI, a video UNI and a craft port. The port mapping package provides a flexible way to associate port numbers with a heterogeneous assortment of ports. + +### 9.1.1 ONT-G + +This managed entity represents the ONT as equipment. The ONT automatically creates an instance of this managed entity. It assigns values to read-only attributes according to data within the ONT itself. + +#### *Relationships* + +All other managed entities in this Recommendation are related directly or indirectly to the ONT-G entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Vendor id:** This attribute identifies the vendor of the ONT. It is the same as the four most significant bytes of the ONT serial number as specified in [ITU-T G.984.3]. (R) (mandatory) (4 bytes) + +**Version:** This attribute identifies the version of the ONT as defined by the vendor. The character value "0" indicates that version information is not available or applicable. (R) (mandatory) (14 bytes) + +**Serial number:** The serial number is unique for each ONT. It is defined in [ITU-T G.984.3] and contains the vendor ID and version number. The first four bytes are an ASCII-encoded vendor ID four letter mnemonic. The second four bytes are a binary encoded serial number, under the control of the ONT vendor. (R) (mandatory) (8 bytes) + +| | | +|------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Traffic management option: |

This attribute identifies the upstream traffic management function implemented in the ONT. There are two options:

0 Priority controlled and flexibly scheduled upstream traffic. The traffic scheduler and priority queue mechanism are used for upstream traffic.

1 Rate controlled upstream traffic. The maximum upstream traffic of each individual connection is guaranteed.

For clarification, see Appendix III.

Downstream priority queues are managed via the GEM port network CTP ME.

Upon ME instantiation, the ONT sets this attribute to the value that describes its implementation. The OLT must adapt its model to conform to the ONT's selection. (R) (mandatory) (1 byte)

| +| VP/VC cross-connection function option: | This attribute is not used. If it is present, it should be set to 0. (R) (optional) (1 byte) | +| Battery backup: | This Boolean attribute specifies whether the ONT/NT supports backup battery monitoring. False disables battery alarm monitoring; true enables battery alarm monitoring. (R, W) (mandatory) (1 byte) | +| Administrative state: | This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) | +| Operational state: | This attribute reports whether the managed entity is currently capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) | +| Actions | | +| Get, set | | +| Reboot: | Reboot the ONT. | +| Test: | Test the ONT. The test action can be used either to perform equipment diagnostics or to measure parameters such as received optical power, video output level, battery voltage, etc. Extensions to the test and test response messages are defined for these purposes; refer to Appendix II. | +| Synchronize time: | This action synchronizes the start time of all performance monitoring managed entities of the ONT with the reference time of the OLT. All counters of all monitoring managed entities are cleared to 0 and restarted. Also, the value of the interval end time attribute of the monitoring managed entities is set to 0 and restarted. See clause I.1.9 for further discussion of PM. | +| Notifications | | +| Test result: | Test results are reported via a test result message if the test is invoked by a test command from the OLT. | + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------------------------| +| 1 | Vendor id | Vendor identification | +| 2 | Version | Version of ONT as defined by vendor | +| 3 | Serial number | Serial number of ONT | +| 4..7 | N/A | | +| 8 | Op state | Operational state change | +| 9..16 | Reserved | | + +#### Alarm + +| Number | Alarm | Description | +|----------|------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Equipment alarm | Functional failure on an internal interface | +| 1 | Powering alarm | Loss of external power | +| 2 | Battery missing | Battery is provisioned but missing | +| 3 | Battery failure | Battery is provisioned and present but cannot recharge | +| 4 | Battery low | Battery is provisioned and present but its voltage is too low | +| 5 | Physical intrusion | Applies if the ONT supports detection such as door or box open | +| 6 | ONT self test failure | ONT has failed autonomous self test | +| 7 | Dying gasp | ONT is powering off imminently | +| 8 | Temperature yellow | No service shutdown at present, but the circuit pack is operating beyond its recommended range | +| 9 | Temperature red | Some services have been shut down to avoid equipment damage. The operational state of the affected PPTPs indicates the affected services | +| 10 | Voltage yellow | No service shutdown at present, but the line power voltage is below its recommended minimum. Service restrictions may be in effect, such as permitting no more than N lines off-hook or ringing at one time | +| 11 | Voltage red | Some services have been shut down to avoid power collapse. The operational state of the affected PPTPs indicates the affected services | +| 12..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.1.2 ONT2-G + +This managed entity contains additional attributes associated with the G-PON ONT. The ONT automatically creates an instance of this managed entity. Its attributes are populated according to the data within the ONT itself. + +#### Relationships + +This managed entity is paired with the ONT-G entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Equipment id:** This attribute may be used to identify the specific type of ONT. In North America, this may be the equipment CLEI code. (R) (optional) (20 bytes) + +**OMCC version:** This attribute identifies the version of the OMCC protocol being used by the ONT. This allows the OLT to manage a network with ONTs that support different OMCC versions. Release levels of this Recommendation may be supported with the following code points: + +0x80 G.984.4 06/04. + +NOTE – For historic reasons, this codepoint may also appear in ONTs that support later versions. + +0x81 G.984.4 Amd.1 (06/05). + +0x82 G.984.4 Amd.2 (03/06). + +0x83 G.984.4 Amd.3 (12/06). + +0x84 G.984.4 (02/08). + +(R) (mandatory) (1 byte) + +**Vendor product code:** This attribute provides a vendor-specific product code for the ONT. (R) (optional) (2 bytes) + +**Security capability:** This attribute advertises the security capabilities of the ONT. The following codepoints are defined: + +0 Reserved. + +1 AES encryption of the downstream payload supported. + +2..255 Reserved. + +(R) (mandatory) (1 byte) + +**Security mode:** This attribute specifies the current security mode of the ONT. All secure GEM ports in an ONT must use the same security mode at any given time. The following codepoints are defined: + +0 Reserved. + +1 AES algorithm used for unicast traffic. + +2..255 Reserved. + +Upon ME instantiation, the ONT sets this attribute to 1, AES. If new encryption modes are standardized, then AES will be the default, and the new modes will be settable via writing to this attribute. This does not mean that any channels are encrypted; that process is negotiated at the PLOAM layer. It only signifies that AES is the security mode to be used on any channels that the OLT may choose to encrypt. (R, W) (mandatory) (1 byte) + +- Total priority queue number:** This attribute reports the total number of priority queues that are not associated with a circuit pack, but with the ONT in its entirety. The maximum value is 0x0FFF. Upon ME instantiation, the ONT sets this attribute to the value that represents its capabilities. (R) (mandatory) (2 bytes) +- Total traffic scheduler number:** This attribute reports the total number of traffic schedulers that are not associated with a circuit pack, but with the ONT in its entirety. The ONT supports null function, HOL scheduling and WRR from the priority control and guarantee of minimum rate control points of view, respectively. If the ONT has no traffic schedulers, this attribute is 0. (R) (mandatory) (1 byte) +- Mode:** This attribute identifies whether the ONT can operate in ATM-only mode (0), GEM-only mode (1), or both ATM and GEM mode (2). ATM mode is deprecated; this attribute should always be set to 1. (R) (mandatory) (1 byte) +- Total GEM port-ID number:** This attribute reports the total number of GEM port-IDs supported by the ONT. The maximum value is 0x0FFF. Upon ME instantiation, the ONT sets this attribute to the value that represents its capabilities. (R) (optional) (2 bytes) +- SysUpTime:** This attribute counts the 10 ms intervals since the ONT was last initialized. It rolls over to 0 when full (See [b-IETF RFC 1213]). (R) (optional) (4 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-----------------------------------| +| 1 | N/A | | +| 2 | OMCC version | OMCC version supported in the ONT | +| 3..9 | N/A | | +| 10..16 | Reserved | | + +### **9.1.3 ONT data** + +This managed entity models the MIB itself. Clause I.1.2 explains the use of this managed entity with respect to MIB synchronization. Clause I.1.4 explains the alarm synchronization process, in which the get alarm messages are directed to the ONT data managed entity. + +The ONT automatically creates an instance of this managed entity, and updates the associated attributes according to data within the ONT itself. + +#### *Relationships* + +One instance of this managed entity is contained in an ONT. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) +- MIB data sync:** This attribute is used to check the alignment of the MIB of the ONT with the corresponding MIB in the OLT. MIB data sync relies on this attribute, which is a sequence number that can be checked by the OLT to see if the MIB snapshots for the OLT and ONT match. Refer to clause I.1.1 for a detailed description of this attribute. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +- Get all alarms:** Latch a snapshot (i.e., copy) of the current alarm statuses of all managed entities and reset the alarm message counter. +- Get all alarms next:** Get the latched alarm status of the next managed entity within the current snapshot. +- MIB reset:** Reset the MIB data sync attribute to 0 and reset the MIB of the ONT to its default state. This default MIB consists of one instance of the ONT-G managed entity, one instance of the ONT data managed entity, two instances of the software image managed entity, zero or more instances of the cardholder managed entity, and zero or more instances of the priority queue-G managed entity (for the priority queues that reside in the ONT). +- MIB upload:** Latch a snapshot (i.e., copy) of the current MIB. Not every managed entity or every attribute is included in a MIB upload. Performance monitoring history data MEs are excluded; table attributes are excluded. Other MEs and attributes, such as the PPTP for the local craft terminal, are excluded as documented in their specific definitions. +- MIB upload next:** Get the latched attribute values of the managed entity within the current snapshot. + +#### *Notifications* + +None. + +### **9.1.4 Software image** + +This managed entity models an executable software image stored in the ONT. + +The ONT automatically creates two instances of this managed entity upon the creation of each managed entity that contains independently-manageable software, either the ONT itself or an individual circuit pack. The ME attributes are populated according to data within the ONT or the circuit pack. + +Some pluggable equipments may contain no software. Others may contain software that is intrinsically bound to the ONT's own software image. No software image ME need exist for such equipments, though it may be convenient for the ONT to create them to support software version audit from the OLT. In this case, the dependent MEs would support only the get action. + +A slot may contain various equipments over its lifetime, and if software image MEs exist, the ONT must automatically create and delete them as the equipage changes. + +When controller packs are duplicated, each can be expected to contain two software image MEs, managed through reference to the individual controller packs themselves. When this occurs, the + +ONT should not have a global pair of software images MEs (instance 0), since an action (download, activate, commit) directed to instance 0 would be ambiguous. + +#### *Relationships* + +Two instances of the software image managed entity are associated with each instance of the ONT or circuit pack whose software is independently managed. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The two-byte value indicates the physical location of the software image. The first byte identifies the ME instance (ONT (0) or slot (1..254)) containing the associated software image ME. The second byte distinguishes between the two software image ME instances (0..1). (R) (mandatory) (2 bytes) + +**Version:** This attribute identifies the version of the software. (R) (mandatory) (14 bytes) + +**Is committed:** This attribute indicates whether the associated software image is committed (1) or uncommitted (0). By definition, the committed software image is loaded and executed upon reboot of the ONT and/or circuit pack. During normal operation, one software image is always committed, while the other is uncommitted. Under no circumstances are both software images allowed to be committed at the same time. On the other hand, both software images could be uncommitted at the same time if both were invalid. Upon ME instantiation, instance 0 is initialized to committed, while instance 1 is initialized to uncommitted (that is, the ONT ships from the factory with image 0 committed). (R) (mandatory) (1 byte) + +**Is active:** This attribute indicates whether the associated software image is active (1) or inactive (0). By definition, the active software image is one that is currently loaded and executing in the ONT or circuit pack. Under normal operation, one software image is always active while the other is inactive. Under no circumstances are both software images allowed to be active at the same time. On the other hand, both software images could be inactive at the same time if both were invalid. (R) (mandatory) (1 byte) + +**Is valid:** This attribute indicates whether the associated software image is valid (1) or invalid (0). By definition, a software image is valid if it has been verified to be an executable code image. The verification mechanism is not subject to standardization; however, at a minimum it must include a data integrity (CRC) check of the entire code image. Upon ME instantiation, the ONT validates the associated code image and sets this attribute according to the result. (R) (mandatory) (1 byte) + +#### *Actions* + +#### **Get** + +NOTE – Figure 9.1.4-1 illustrates the life cycle of software images under the following actions. State S0 is a conceptual initialization state when neither of the software images is valid (i.e., executable). During S0, the OMCC is not functional. + +All of the following actions are mandatory for ONTs with remotely manageable software. + +- Start download:** Initiate a software download sequence. This action is valid only for a software image that is currently inactive and uncommitted (i.e., not selected as the boot image). +- Download section:** Download a section of a software image. This action is valid only for a software image that is currently being downloaded (image 1 in state S2, image 0 in state S2'). +- End download:** Signal the completion of a download sequence, providing both CRC and version information for final verification of a downloaded software image. This action is valid only for a software image that is currently being downloaded (image 1 in state S2, image 0 in state S2'). +- Activate image:** Load/execute a valid software image. When this action is applied to a software image that is currently inactive, execution of the current code image is suspended, the associated software image is loaded from non-volatile memory, and execution of this new code image is initiated (that is, the associated entity re-boots on the previously inactive image). When this action is applied to a software image that is already active, a soft restart is performed. The software image is not reloaded from non-volatile memory; the current volatile code image is simply restarted. This action is only valid for a valid software image. +- Commit image:** Select a valid software image to be the default image to be loaded and executed by the boot code upon start-up (i.e., set the is committed attribute value to 1 for the associated software image ME and set the is committed attribute value to 0 for the other software image). This action is only valid for a valid software image. + +#### *Notifications* + +None. + +![Software image state diagram showing states S0 through S4 and S0' through S4' with transitions for reboot, activate, commit, start download, and end download.](5a9cdc1fed33ae8fb871a8cd4d591729_img.jpg) + +The diagram illustrates the state transitions for software images 0 and 1. Each state is represented by a rounded rectangle containing two columns: **SW image 0** and **SW image 1**. Each column lists the status of *is active*, *is committed*, *is valid*, and *version*. + +- State S0 (OMCC not operational)**: Both images are inactive, uncommitted, invalid, and have null versions. +- State S1**: SW image 0 is active, committed, valid, version xxxx. SW image 1 is inactive, uncommitted, invalid, version null. +- State S1'**: SW image 0 is inactive, uncommitted, invalid, version null. SW image 1 is active, committed, valid, version yyyy. +- State S2**: SW image 0 is active, committed, valid, version xxxx. SW image 1 is inactive, uncommitted, invalid, version null. +- State S2'**: SW image 0 is inactive, uncommitted, invalid, version null. SW image 1 is active, committed, valid, version yyyy. +- State S3**: SW image 0 is active, committed, valid, version xxxx. SW image 1 is inactive, uncommitted, valid, version yyyy. +- State S3'**: SW image 0 is inactive, uncommitted, valid, version xxxx. SW image 1 is active, committed, valid, version yyyy. +- State S4**: SW image 0 is inactive, committed, valid, version xxxx. SW image 1 is active, committed, valid, version yyyy. +- State S4'**: SW image 0 is active, committed, valid, version xxxx. SW image 1 is inactive, committed, valid, version yyyy. + +Transitions between states are triggered by events such as *reboot*, *activate (0/1)*, *commit (0/1)*, *start download (0/1)*, *end download (0/1)*, and *successful completion of initial (proprietary) bootstrap of SW image 0/1*. Some transitions include error conditions like *incorrect CRC*. + +Software image state diagram showing states S0 through S4 and S0' through S4' with transitions for reboot, activate, commit, start download, and end download. + +G.984.4(08)\_F9.1.4-1 + +Figure 9.1.4-1 – Software image state diagram + +### 9.1.5 Cardholder + +The cardholder represents the fixed equipment slot configuration of the ONT. One or more of these entities is contained in the ONT. Each cardholder can contain 0 or 1 circuit packs; the circuit pack models equipment information that can change over the lifetime of the ONT, e.g., through replacement. + +An instance of this managed entity exists for each physical slot in an ONT that has pluggable circuit packs. One or more instances of this managed entity may also exist in an integrated ONT, to represent virtual slots. Instances of this managed entity are created automatically by the ONT, and the status attributes are populated according to data within the ONT itself. + +There is potential for conflict in the semantics of the expected plug-in unit type, the expected port count and the expected equipment id, both when the slot is not populated and when a new circuit pack is inserted. The expected plug-in unit type and the plug-in type mismatch alarm are mandatory, although *plug-and-play/unknown* (circuit pack type 255) may be used as a way to minimize their significance. It is recommended that an ONT deny the provisioning of inconsistent combinations of expected equipment attributes. + +When a circuit pack is plugged into a cardholder, or when a cardholder is preprovisioned to expect a circuit pack of a given type, it may trigger the ONT to instantiate a number of managed entities and update the values of others, depending on the circuit pack type. The ONT may also delete a variety of other managed entities when a circuit pack is reprovisioned to expect no circuit pack or a circuit pack of a different type. These actions are described in the definitions of the various managed entities. + +Expected equipment id and expected port count are alternate ways to trigger the same preprovisioning effects. These tools may be useful if an ONT is prepared to accept more than one circuit pack of a given type but with different port counts, or if a circuit pack is a hybrid that matches none of the types in Table 9.1.5-1, but whose identification (e.g., part number) is known. + +#### *Relationships* + +An ONT may contain one or more instances of the cardholder, each of which may contain an instance of the circuit pack managed entity. The slot id, real or virtual, is a fundamental identification mechanism for managed entities with some relationship to physical location. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The ONT sets the first byte of this two-byte identifier to: + +- | | | +|---|--------------------------------------------------| +| 0 | if the ONT contains pluggable equipment modules; | +| 1 | if the ONT is a single integrated equipment. | + +The second byte of this identifier is the slot number. In integrated ONTs, this byte may be used as a virtual slot or set to 0 to indicate a universal pseudo-slot. + +Slot numbering schemes differ among vendors. It is only required that slot numbers be unique across the ONT. Up to 254 equipment slots are supported in the range 1..254 (Note 1). The value 0 is reserved to indicate a universal pseudo-slot. The value 255 is also reserved. (R) (mandatory) (2 bytes) + +NOTE 1 – Some xDSL managed entities use the two most significant bits of the slot number for other purposes. An ONT that supports these services may have slot limitations or restrictions. + +**Actual plug-in unit type:** This attribute is equal to the type of the circuit pack in the cardholder or 0 if the cardholder is empty. This attribute is then redundant with the type attribute of the circuit pack managed entity. Circuit pack types are defined in Table 9.1.5-1. (R) (mandatory) (1 byte) + +The three following attributes permit the OLT to specify its intentions for future equipage of a slot. Once some or all of these are set, the ONT can proceed to instantiate circuit pack and PPTP MEs, along with other predeterminable MEs, and allow the OLT to create related discretionary MEs, thereby supporting service preprovisioning. + +**Expected plug-in unit type:** This attribute provisions the type of circuit pack for the slot. For type coding, see Table 9.1.5-1. The value 0 means that the cardholder is not provisioned to contain a circuit pack. The value 255 means that the cardholder is configured for plug-and-play. Upon ME instantiation, the ONT sets this attribute to 0. For integrated interfaces, this attribute may be used to represent the type of interface. (R, W) (mandatory) (1 byte) + +**Expected port count:** This attribute permits the OLT to specify the number of ports it expects in a circuit pack. Prior to provisioning by the OLT, the ONT initializes this attribute to 0. (R, W) (optional) (1 byte) + +**Expected equipment id:** This attribute provisions the specific type of expected circuit pack. This attribute applies only to ONTs that do not have integrated interfaces. In North America, this may be the expected equipment CLEI code. Upon ME instantiation, the ONT sets this attribute to all spaces. (R, W) (optional) (20 bytes) + +**Actual equipment id:** This attribute identifies the specific type of circuit pack, once it is installed. This attribute applies only to ONTs that do not have integrated interfaces. In North America, this may be the equipment CLEI code. When the slot is empty or the equipment ID is not known, this attribute should be set to all spaces. (R) (optional) (20 bytes) + +**Protection profile pointer:** This attribute indicates an equipment protection profile that may be associated with the cardholder. Its value is the least significant byte of the managed entity ID of the equipment protection profile with which it is associated, or 0 if equipment protection is not used. (R) (optional) (1 byte) + +**Invoke protection switch:** The OLT may use this attribute to control equipment protection switching. Code points have the following meaning when set by the OLT: + +- 0 Release protection switch. +- 1 Operate protection switch, protect cardholder unspecified. +- 2 Operate protection switch, use first protect cardholder. +- 3 Operate protection switch, use second protect cardholder. + +The ONT should deny attempts to switch to an unequipped, defective or already active protection cardholder. + +Upon the get action from the OLT, this attribute should return the current value of the actual protection configuration. Code points are as defined above, except that the value 1 is never returned. + +When circuit packs that support a PON IF function are switched, the response should be returned on the same PON that received the command. However, the OLT should also be prepared to accept a response on the redundant PON. (R, W) (optional) (1 byte) + +#### Actions + +#### Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------| +| 1 | Actual type | Actual type of circuit pack in cardholder | +| 2..4 | N/A | | +| 5 | Actual equipment id | Actual equipment ID of circuit pack in cardholder | +| 6..7 | N/A | | +| 8..16 | Reserved | | + +**Alarm:** If no circuit pack is configured or if the cardholder is configured for plug-and-play with no expected equipment ID, no alarms are raised. No alarms are defined for ONTs with integrated interfaces. + +| Number | Alarm | Description | +|----------|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Plug-in LIM missing alarm | Configured circuit pack is not present. If the plug-in LIM missing alarm is active, none of the mismatch alarms are declared. | +| 1 | Plug-in type mismatch alarm | Inserted circuit pack is wrong type | +| 2 | Improper card removal | Circuit pack has been removed without being de-provisioned. This is a redundant alarm that helps the OLT distinguish between transitions from state S2 to state S1 (Figure 9.1.5-1) and transitions from state S4 to state S1. This alarm is sent only when a transition occurs from state S2 to state S1. | +| 3 | Plug in equipment id mismatch alarm | Inserted circuit pack has wrong equipment ID | +| 4 | Protection switch | An autonomous equipment protection switch has occurred. This notification is reported by the protected cardholder. | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific | Not to be standardized | + +Figure 9.1.5-1 is a state diagram that describes insertion and removal of a particular circuit pack into/from a cardholder that is provisioned to a specific type or to plug-and-play. + +NOTE 2 – The state diagram is not applicable for ONTs with integrated interfaces. + +![Cardholder state diagram showing states S0, S1, S2, S3, S3', S4, S5, S6, S7, S8, and S9 with transitions for circuit pack operations like insert, remove, set expected type, delete, and create.](1b23b78336d8bd286c653cbdb38428dd_img.jpg) + +The diagram illustrates the state transitions for a Cardholder. Each state box contains the Cardholder's actual type and expected type. + +- state S0**: actual type: no LIM, expected type: no LIM +- state S1**: actual type: no LIM, expected type: X +- state S2**: actual type: X, expected type: X +- state S3**: actual type: Y, expected type: no LIM +- state S3'**: actual type: X, expected type: no LIM +- state S4**: actual type: Y, expected type: X +- state S5**: actual type: no LIM, expected type: plug-and-play +- state S6**: actual type: no LIM, expected type: plug-and-play +- state S7**: actual type: X, expected type: plug-and-play +- state S8**: actual type: X, expected type: plug-and-play +- state S9**: actual type: Y, expected type: plug-and-play + +Transitions are triggered by specific actions and result in changes to the Cardholder's state, often accompanied by alarms or automatic creation/deletion of circuit packs. + +**Note:** the secondary MEs shown as auto-created or auto-deleted are appropriate for circuit packs that provide subscriber interface (UNI) functions. Other types of circuit packs have different secondary MEs, or no secondary MEs, according to the definition of the MEs and the function of the circuit pack. + +Cardholder state diagram showing states S0, S1, S2, S3, S3', S4, S5, S6, S7, S8, and S9 with transitions for circuit pack operations like insert, remove, set expected type, delete, and create. + +Figure 9.1.5-1 – Cardholder state diagram + +Some of the following circuit pack types are obsolete in G-PON applications. Their code points and definitions are reserved for backward compatibility but, in the interest of brevity, they are not listed. + +**Table 9.1.5-1 – Circuit pack types** + +| Coding | Content | Description | +|---------|--------------------------------------|----------------------------------------------------------------------------------------------------------------------| +| 0 | No LIM | Default value | +| 1..12 | See [ITU-T G.983.2] | Various ATM-based UNIs | +| 13 | C1.5 (DS1) | 1.544 Mbit/s local (T-interface) module | +| 14 | C2.0 (E1) | 2.048 Mbit/s local (T-interface) module | +| 15 | C6.3 (J2) | 6.312 Mbit/s local (T-interface) module | +| 16 | C-DS1/E1 | Configurable DS1/E1 module | +| 17 | C-DS1/E1/J1 | Configurable DS1/E1/J1 module | +| 18 | C6.3U (J2) | 6.312 Mbit/s remote (U-interface) module | +| 19 | C192k | 192 kbit/s local (T-interface) module | +| 20 | C44.7 (DS3) | 44.736 Mbit/s local (T-interface) module | +| 21 | C34.3 (E3) | 34.368 Mbit/s local (T-interface) module | +| 22 | 10BaseT | 10 BaseT Ethernet LAN IF | +| 23 | 100BaseT | 100 BaseT Ethernet LAN IF | +| 24 | 10/100BaseT | 10/100 BaseTx Ethernet LAN IF (Note) | +| 25..27 | See [ITU-T G.983.2] | Various non-Ethernet LAN technologies | +| 28 | C1.5 (J1) | 1.544 Mbit/s local (T-interface) module | +| 29 | A150SMF SONET | ATM OC-3 SMF UNI | +| 30 | A150MMF SONET | ATM OC-3 MMF UNI | +| 31 | A150UTP SONET | ATM OC-3 UTP UNI | +| 32 | POTS | Plain old telephony service | +| 33 | ISDN-BRI | ISDN basic rate interface | +| 34 | Gigabit optical Ethernet | Gigabit Ethernet optical IF (Note) | +| 35 | xDSL | xDSL IF | +| 36 | SHDSL | SHDSL IF | +| 37 | VDSL | VDSL IF ([ITU-T G.993.1]) | +| 38 | Video service | Video module | +| 39 | LCT | Local craft terminal interface | +| 40 | 802.11 | [IEEE 802.11] interface | +| 41 | xDSL/POTS | Combination xDSL and POTS interfaces | +| 42 | VDSL/POTS | Combination VDSL ([ITU-T G.993.1]) and POTS interfaces | +| 43 | Common equipment | Circuit packs such as removable power supply modules or ONU controllers | +| 44 | Combined video UNI and PON interface | Circuit pack that combines both functions | +| 45 | Mixed services equipment | Circuit pack with several types of ANI and/or UNI. Suggested for use with the port mapping package-G managed entity. | +| 46 | MoCA | MoCA | +| 47 | 10/100/1000BaseT | 10/100/1000 BaseTx Ethernet LAN IF (Note) | +| 48..191 | Reserved | | + +**Table 9.1.5-1 – Circuit pack types** + +| Coding | Content | Description | +|----------|----------------------------|----------------------------------------------------------------------------------------------------------------------------| +| 192..223 | Vendor-specific | Reserved for vendor use, not to be standardized | +| 224..242 | Reserved | | +| 243 | GPON1244155 | G-PON interface, 1244 Mbit/s downstream and 155 Mbit/s upstream | +| 244 | GPON1244622 | G-PON interface, 1244 Mbit/s downstream and 622 Mbit/s upstream | +| 245 | GPON12441244 | G-PON interface, 1244 Mbit/s downstream and 1244 Mbit/s upstream | +| 246 | GPON2488155 | G-PON interface, 2488 Mbit/s downstream and 155 Mbit/s upstream | +| 247 | GPON2488622 | G-PON interface, 2488 Mbit/s downstream and 622 Mbit/s upstream | +| 248 | GPON24881244 | G-PON interface, 2488 Mbit/s downstream and 1244 Mbit/s upstream | +| 249 | GPON24882488 | G-PON interface, 2488 Mbit/s downstream and 2488 Mbit/s upstream | +| 250..254 | See [ITU-T G.983.2] | G-PON and B-PON interfaces of diverse rates | +| 255 | Plug-and-play/unknown | Plug-and-play (for the cardholder managed entity only).
Unrecognized module (for the circuit pack managed entity only). | + +NOTE – Codepoints 24 and 34 were used by some implementations to represent the 10/100/1000BaseT interface because codepoint 47 was not defined at the time. While codepoint 47 should be adopted for this interface at the earliest opportunity, near-term interoperability may require the flexible recognition of these other codepoints. + +### 9.1.6 Circuit pack + +This managed entity models a circuit pack that is equipped in an ONT slot. For ONTs with integrated interfaces, this managed entity may be used to distinguish available types of interfaces (the port mapping package is another way). + +For ONTs with integrated interfaces, the ONT automatically creates an instance of this managed entity for each instance of the virtual cardholder managed entity. The ONT also creates an instance of this managed entity when the OLT provisions the cardholder to expect a circuit pack (i.e., when the OLT sets the expected plug-in unit type or equipment ID of the cardholder to a circuit pack type, as defined in clause 9.1.5). The ONT also creates an instance of this managed entity when a circuit pack is installed in a cardholder whose expected plug-in unit type is 255 = plug-and-play, and whose equipment ID is not provisioned. Finally, when the cardholder is provisioned for plug-and-play, an instance of this managed entity can be created at the request of the OLT. + +The ONT deletes an instance of this managed entity when the OLT de-provisions the circuit pack (i.e., when the OLT sets the expected plug-in unit type or equipment ID of the cardholder to 0 = no LIM). The ONT also deletes an instance of this managed entity on request of the OLT if the expected plug-in unit type attribute of the corresponding cardholder is equal to 255, plug-and-play, and the expected equipment ID is blank (a string of all spaces). ONTs with integrated interfaces do not delete circuit pack instances. + +NOTE – Creation and deletion by the OLT is retained for backward compatibility. + +#### *Relationships* + +An instance of this managed entity is contained by an instance of the cardholder managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Its value is the same as that of the cardholder managed entity containing this circuit pack instance. (R, Set-by-create (if applicable)) (mandatory) (22 bytes) +- Type:** This attribute identifies the circuit pack type. This attribute is a code as defined in Table 9.1.5-1. The value 255 means unknown or undefined, i.e., the inserted circuit pack is not recognized by the ONT or is not mapped to an entry in Table 9.1.5-1. In the latter case, the equipment ID attribute may contain inventory information. Upon autonomous ME instantiation, the ONT sets this attribute to 0 or to the type of the circuit pack that is physically present. (R, Set-by-create (if applicable)) (mandatory) (1 byte) +- Number of ports:** This attribute is the number of access ports on the circuit pack. If the port mapping package-G is supported for this circuit pack, this attribute should be set to the total number of ports of all types. (R) (optional) (1 byte) +- Serial number:** The serial number is unique for each circuit pack. Note that the serial number may contain the vendor ID and/or version number. For integrated ONTs, this value is identical to the value of the serial number attribute of the ONT-G managed entity. Upon creation in the absence of a physical circuit pack, this attribute comprises all spaces. (R) (mandatory) (8 bytes) +- Version:** This attribute is a string that identifies the version of the circuit pack as defined by the vendor. The value 0 indicates that version information is not available or applicable. For integrated ONTs, this value is identical to the value of the version attribute of the ONT-G managed entity. Upon creation in the absence of a physical circuit pack, this attribute comprises all spaces. (R) (mandatory) (14 bytes) +- Vendor id:** This attribute identifies the vendor of the circuit pack. For ONTs with integrated interfaces, this value is identical to the value of the vendor ID attribute of the ONT-G managed entity. Upon creation in the absence of a physical circuit pack, this attribute comprises all spaces. (R) (optional) (4 bytes) +- Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by the circuit pack. When the administrative state is set to lock, all user functions of this circuit pack are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W, Set-by-create (if applicable)) (mandatory) (1 byte) +- Operational state:** This attribute indicates whether or not the circuit pack is capable of performing its function. Valid values are enabled (0), disabled (1) and unknown (2). Pending completion of initialization and self test on an installed circuit pack, the ONT sets this attribute to 2. (R) (optional) (1 byte) + +**Bridged or IP ind:** This attribute specifies whether the Ethernet interface is bridged or derived from an IP router function. + +0 Bridged. +1 IP router. +2 Both bridged and IP router functions. + +(R, W) (optional, only applicable for circuit packs with Ethernet interfaces) (1 byte) + +**Equipment id:** This attribute may be used to identify the vendor's specific type of circuit pack. In North America, this may be the CLEI code. Upon ME instantiation, the ONT sets this attribute to all spaces or to the equipment ID of the circuit pack that is physically present. (R) (optional) (20 bytes) + +**Card configuration:** This attribute selects the appropriate configuration on configurable circuit packs (e.g., T1/E1). Table 9.1.5-1 specifies three configurable card types: A45/34 (code 9), C-DS1/E1 (code 16), and C-DS1/E1/J1 (code 17). Values are indicated below for the allowed card types and configurations. + +| Card type | Configuration | Value | +|------------------|----------------------|--------------| +| A45/34 | ATM 44.736 Mbit/s | 0 | +| | ATM 34.368 Mbit/s | 1 | +| C-DS1/E1 | DS1 | 0 | +| | E1 | 1 | +| C-DS1/E1/J1 | DS1 | 0 | +| | E1 | 1 | +| | J1 | 2 | + +Upon autonomous instantiation, this attribute is set to 0. (R, W, Set-by-create (if applicable)) (mandatory for configurable circuit packs) (1 byte) + +**Total T-CONT buffer number:** This attribute reports the total number of T-CONT buffers associated with the circuit pack. Upon ME instantiation, the ONT sets this attribute to 0 or to the value supported by the physical circuit pack. (R) (mandatory for circuit packs that provide a traffic scheduler function) (1 byte) + +**Total priority queue number:** This value reports the total number of priority queues associated with the circuit pack. Upon ME instantiation, the ONT sets the attribute to 0 or to the value supported by the physical circuit pack. (R) (mandatory for circuit packs that provide a traffic scheduler function) (1 byte) + +**Total traffic scheduler number:** This value reports the total number of traffic schedulers associated with the circuit pack. The ONT supports null function, HOL (head of line) scheduling and WRR (weighted round robin) from the priority control and guarantee of minimum rate control points of view, respectively. If the circuit pack has no traffic scheduler, this attribute should be 0. Upon ME instantiation, the ONT sets the attribute to 0 or to the value supported by the physical circuit pack. (R) (mandatory for circuit packs that provide a traffic scheduler function) (1 byte) + +**Power shed override:** This attribute allows ports to be excluded from the power shed control defined in clause 9.1.7. It is a bit mask that takes port 1 as the MSB; a bit value of 1 marks the corresponding port to override the power shed timer. For hardware that cannot shed power per port, this attribute is a slot override rather than a port override, with any non-zero port value causing the entire circuit pack to override power shedding. (R, W) (optional) (4 bytes) + +#### *Actions* + +#### **Get, set** + +**Create, delete:** Optional, only when plug-and-play is supported. + +**Reboot:** Reboot the circuit pack. + +**Test:** Test the circuit pack (optional). The test action may be used either to perform equipment diagnostics or to measure parameters such as received optical power, video output level, battery voltage, etc. Extensions to the test and test response messages are defined for these purposes; refer to Appendix II. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..6 | N/A | | +| 7 | Op state | Operational state change | +| 8..14 | N/A | | +| 15..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|----------|------------------------|-----------------------------------------------------------------------------------------------------------------------------------| +| 0 | Equipment alarm | A failure on an internal interface or failed self test | +| 1 | Powering alarm | Fuse failure or failure of DC/DC converter | +| 2 | Self test failure | Failure of circuit pack autonomous self test | +| 3 | Laser end of life | Failure of transmit laser imminent | +| 4 | Temperature yellow | No service shutdown at present, but the circuit pack is operating beyond its recommended range | +| 5 | Temperature red | Service has been shut down to avoid equipment damage. The operational state of the affected PPTPs indicates the affected services | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.1.7 ONT power shedding** + +This managed entity models the ONT's ability to shed services when the ONT goes into battery operation mode after AC power failure. Shedding classes are defined, which may span multiple circuit pack types. This feature works in conjunction with the power shed override attribute of the circuit pack managed entity, which can selectively prevent power shedding of priority ports. + +An ONT that supports power shedding automatically creates an instance of this managed entity. + +The following table defines the binding of shedding class and PPTP type. The coding is taken from Table 9.1.5-1. In the case of hybrid LIM types, multiple shedding classes may affect a circuit pack if the hardware is capable of partial power shedding. + +An ONT may choose to model its ports with the port mapping package-G of clause 9.1.8, rather than with real or virtual circuit packs. In this case, power shedding pertains to individual PPTPs, as listed in the second column of the table. + +| Shedding class | PPTP type | Coding | Content | +|----------------------------|---------------|--------|----------------------------------------------------| +| ATM | ATM PPTP | 1..12 | Various ATM UNIs | +| CES | CES PPTP | 13 | C1.5 (DS1) | +| | | 14 | C2.0 (E1) | +| | | 15 | C6.3 (J2) | +| | | 16 | C-DS1/E1 | +| | | 17 | C-DS1/E1/J1 | +| | | 18 | C6.3U (J2) | +| | | 19 | C192k | +| | | 20 | C44.7 (DS3) | +| | | 21 | C34.3 (E3) | +| Data | Ethernet PPTP | 22 | 10BaseT | +| | | 23 | 100BaseT | +| | | 24 | 10/100BaseT | +| Frame | Unspecified | 25..27 | Non-Ethernet LANs | +| CES | CES PPTP | 28 | C1.5 (J1) | +| SONET | SONET | 29 | A150SMF SONET | +| | | 30 | A150MMF SONET | +| | | 31 | A150UTP SONET | +| Voice | POTS PPTP | 32 | POTS | +| | ISDN PPTP | 33 | ISDN-BRI | +| Data | Ethernet PPTP | 34 | Gigabit optical Ethernet | +| DSL | xDSL PPTP | 35 | xDSL | +| | Unspecified | 36 | SHDSL | +| | VDSL PPTP | 37 | [ITU-T G.993.1] VDSL | +| N/A | Video UNI | 38 | Video service | +| N/A | LCT PPTP | 39 | LCT | +| Data | 802.11 PPTP | 40 | 802.11 | +| Voice (DSL may also apply) | xDSL + POTS | 41 | xDSL/POTS | +| | VDSL + POTS | 42 | [ITU-T G.993.1] VDSL/POTS | +| N/A | Unspecified | 43 | Common equipment | +| | Unspecified | 44 | Combined video, PON | +| | Unspecified | 45 | Mixed services (power shedding based on port type) | + +| Shedding class | PPTP type | Coding | Content | +|----------------|----------------|----------|----------------------| +| Data | MOCA PPTP | 46 | MoCA | +| Data | Ethernet PPTP | 47 | 10/100/1000BaseT | +| N/A | PON PPTP | 243..254 | G-PON and B-PON ANIs | +| Video overlay | Video ANI PPTP | | | +| Video return | Video RPD | | | + +#### Relationships + +One instance of this managed entity is associated with the ONT managed entity. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Restore power timer reset interval:** The time delay, in seconds, before resetting shedding timers after full power restoration. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (2 bytes) + +For each class of service, an interval attribute is defined below. The value 0 disables power shedding, while the value 1 enables immediate power shed, that is, as soon as AC power fails. Other values specify the time, in seconds, to keep the service active after AC failure before shutting them down and shedding power. Upon ME instantiation, the ONT sets each of the interval attributes to 0. + +**Data class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Voice class shedding interval:** Note that this attribute only pertains to voice services that terminate on the ONT, not to voice services that may reside in the customer premises served by a data type port. (R, W) (mandatory) (2 bytes) + +**Video overlay class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Video return class shedding interval:** (R, W) (mandatory) (2 bytes) + +**DSL class shedding interval:** (R, W) (mandatory) (2 bytes) + +**ATM class shedding interval:** (R, W) (mandatory) (2 bytes) + +**CES class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Frame class shedding interval:** (R, W) (mandatory) (2 bytes) + +**SONET class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Shedding status:** Boolean indication of power shedding status for each shedding class. If this two-byte field is depicted 0b ABCD EFGH IJKL MNOP, its bits are assigned: + +- A Data class +- B Voice class +- C Video overlay class +- D Video return class +- E DSL class +- F ATM class +- G CES class +- H Frame class +- I SONET class +- J..P Reserved and set to 0 + +The ONT sets each bit when power shedding is active, and clears it when the service is restored. (R) (optional) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------------------------| +| 1..10 | N/A | | +| 11 | Shedding status | State change of a shedding function | +| 12..16 | Reserved | | + +### **9.1.8 Port mapping package-G** + +This managed entity provides a way to map a heterogeneous set of physical path termination points (ports) to a parent equipment, which may be a cardholder or the ONT itself. It could be useful, for example, if a single plug-in circuit pack contained a PON ANI as port 1, a video UNI as port 2, and a craft UNI as port 3. It also provides an option for an integrated ONT to represent its ports without the use of virtual cardholders and virtual circuit packs. + +If the port mapping package-G is supported for the ONT as a whole, it is automatically created by the ONT. If the port mapping package-G is supported for plug-in circuit packs, it is created and destroyed by the ONT when the corresponding circuit pack is installed or preprovisioned in a cardholder. + +The port list attributes specify ports 1..64 sequentially. Each port list contains a sequence of ME types, as defined in Table 11-2. These ME type codes define what kind of PTP or ANI corresponds to the specific port number. For example, for a circuit pack with 4 POTS ports, 2 VDSL ports, and 1 video port, numbered sequentially in that order, the attributes would be coded: + +- Max ports: 7 +- Port list 1: 53, 53, 53, 53, 117, 117, 82, 0 +- Port list 2..8: All zero + +#### *Relationships* + +A port mapping package-G may be contained by an ONT-G or a cardholder. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the ONT-G or cardholder. (R) (mandatory) (2 bytes) + +**Max ports:** This attribute indicates the largest port number contained in the port list attributes. Ports are numbered from 1 to this maximum, possibly with embedded 0 entries, but no port may exist beyond the maximum. (R) (mandatory) (1 byte) + +Each of the following attributes is a list of 8 ports, in increasing port number sequence. Each list entry is a two-byte field containing the managed entity type of the UNI or ANI corresponding to the port number. Managed entity types are defined in Table 11-2. Placeholders for unused port numbers are indicated with the value 0. + +**Port list 1:** (R) (mandatory) (16 bytes) + +**Port list 2:** (R) (optional) (16 bytes) + +**Port list 3:** (R) (optional) (16 bytes) + +**Port list 4:** (R) (optional) (16 bytes) + +**Port list 5:** (R) (optional) (16 bytes) + +**Port list 6:** (R) (optional) (16 bytes) + +**Port list 7:** (R) (optional) (16 bytes) + +**Port list 8:** (R) (optional) (16 bytes) + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.1.9 Equipment extension package** + +This managed entity supports optional extensions to circuit pack managed entities. If the circuit pack supports these features, the ONT creates and deletes this managed entity along with its associated real or virtual circuit pack. + +#### *Relationships* + +An equipment extension package may be contained by an ONT-G or cardholder. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the ONT-G or cardholder. (R) (mandatory) (2 bytes) + +**Environmental sense:** This attribute provisions an ONT that supports external sense points, for example physical security detectors at an enclosure. Each pair of bits is defined as follows: + +- 00 Sense point disabled (default). +- 01 Report contact closure. +- 10 Report contact open. +- 11 Sense point disabled (same as 00). + +If the byte is represented in binary as 0B lhgg ffee ddcc bbaa, bits lh correspond to sense point 1, while bits aa correspond to sense point 8. (R, W) (optional) (2 bytes) + +NOTE – Some specific sense point applications are already defined on the ONT-G managed entity. It is the vendor's choice how to configure and report sense points that appear both generically and specifically. + +##### **Contact closure output:** + +This attribute provisions an ONT that supports external contact closure outputs, for example sump pump or air conditioner activation at an ONT enclosure. A contact point is said to be released when it is not energized. Whether this corresponds to an open or a closed electrical circuit depends on the ONT's wiring options. Upon ONT initialization, all contact points should go to the released state. + +If the byte is represented in binary as 0B lhgg ffee ddcc bbaa, bits lh correspond to contact output point 1, while bits aa correspond to contact output point 8. + +On write, the bits of this attribute have the following meaning: + +- 0x No change to contact output point state. +- 10 Release contact output point. +- 11 Operate contact output point. + +On read, the left bit in each pair should be set to 0 at the ONT and ignored at the OLT. The right bit indicates a released output point with 0 and an operated point with 1. (R, W) (optional) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +##### **Alarm** + +| Number | Alarm | Description | +|--------|---------------|------------------------------------| +| 0 | Reserved | | +| 1 | Sense point 1 | Environmental sense point 1 active | +| 2 | Sense point 2 | Environmental sense point 2 active | +| 3 | Sense point 3 | Environmental sense point 3 active | +| 4 | Sense point 4 | Environmental sense point 4 active | +| 5 | Sense point 5 | Environmental sense point 5 active | + +| Number | Alarm | Description | +|----------|------------------------|------------------------------------| +| 6 | Sense point 6 | Environmental sense point 6 active | +| 7 | Sense point 7 | Environmental sense point 7 active | +| 8 | Sense point 8 | Environmental sense point 8 active | +| 9..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.1.10 Protection data + +This managed entity models the capability and parameters of PON protection. An ONT that supports PON protection automatically creates an instance of this managed entity. + +NOTE – Equipment protection is modelled with the equipment protection profile and cardholder managed entities. + +#### *Relationships* + +One instance of this managed entity is associated with two instances of the ANI-G. One of the ANI-G managed entities represents the working side; the other represents the protection side. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This ME is numbered in ascending order from 0. (R) (mandatory) (2 bytes) + +**Working ANI-G pointer:** This attribute points to the ANI-G managed entity that represents the working side of PON protection. (R) (mandatory) (2 bytes) + +**Protection ANI-G pointer:** This attribute points to the ANI-G managed entity that represents the protection side of PON protection. (R) (mandatory) (2 bytes) + +**Protection type:** This attribute indicates the type of PON protection. Valid values are: + +- 0 1+1 protection. +- 1 1:1 protection without extra traffic. +- 2 1:1 protection with ability to support extra traffic. + +(R) (mandatory) (1 byte) + +**Revertive ind:** This attribute indicates whether protection is revertive (1) or non-revertive (0). (R) (mandatory) (1 byte) + +**Wait to restore time:** This attribute specifies the time, in seconds, to wait after a fault clear before switching back to the working side. Upon ME instantiation, the ONT sets this attribute to 3 seconds. (R, W) (mandatory) (2 bytes) + +**Switching guard time:** This attribute specifies the time, in milliseconds, to wait after the detection of a fault before performing a protection switch. Selection of a default value for this attribute is outside the scope of this Recommendation, as it is normally handled through supplier-operator negotiations. (R, W) (optional) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### 9.1.11 Equipment protection profile + +This managed entity supports equipment protection. There can be as many as two protection slots protecting as many as eight working slots. Each of the working and protect cardholder managed entities should refer to the equipment protection profile that defines its protection group. Instances of this managed entity are created and deleted by the OLT. + +An ONT should deny pre-provisioning that would create impossible protection groupings because of slot or equipment incompatibilities. In the same way, the ONT should deny creation or addition to protection groups that cannot be supported by the current equipage. Even so, an inconsistent card type alarm is defined, for example to cover the case of a plug-and-play circuit pack installed in a protection group cardholder that cannot support it. + +#### *Relationships* + +An instance of this object points to the working and protect cardholders, which in turn point back to this managed entity. + +#### *Attributes* + +| | | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. The first byte is 0. The second byte is assigned by the OLT, and must be unique and non-zero. (R, Set-by-create) (mandatory) (2 bytes) | +| Protect slot 1,
protect slot 2: | This pair of attributes describes the protecting cardholder entities in an equipment protection group. There can be one or two protecting entities.
0            Undefined entry (default), a place-holder if there are fewer than two protecting entities in the protection group.
1..254   Slot number of the protecting circuit pack.
(R, W, Set-by-create) (at least one entry mandatory) (1 byte * 2 attributes) | +| working slot 1,
working slot 2,
working slot 3,
working slot 4,
working slot 5,
working slot 6,
working slot 7,
working slot 8 | This group of attributes describes the working cardholder entities in an equipment protection group. There can be up to eight working entities.
0            Undefined entry (default), a place-holder if there are fewer than eight working entities in the protection group.
1..254   Slot number of the working circuit pack.
(R, W, Set-by-create) (at least one entry mandatory) (1 byte * 8 attributes) | +| Protect status 1,
protect status 2: | This pair of attributes indicates whether each protection cardholder is currently protecting some other cardholder and, if so, which one.
0            Not protecting any other cardholder.
1..254   Slot number of the working cardholder currently being protected by this ME.
(R) (mandatory) (1 byte * 2 attributes) | +| Revertive ind: | This attribute specifies whether equipment protection is revertive. The default value 0 indicates revertive switching; any other value indicates non-revertive switching. (R, W, Set-by-create) (optional) (1 byte) | + +**Wait to restore time:** This attribute specifies the time, in minutes, during which a working equipment must be free of error before a revertive switch occurs. It defaults to 0. (R, W, Set-by-create) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +##### **Alarm** + +| Number | Alarm | Description | +|----------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Inconsistent card type | The expected or actual circuit pack type in a slot is incapable of participating in the equipment protection group, either because it is not subject to equipment protection or because its type or equipment ID differs from that previously defined for the other cardholders of the group. When possible, the ONT should deny provisioning attempts that would create incompatibilities but, for example, in the case of plug-and-play, it may not be possible to forestall the inconsistency. | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.1.12 ONT remote debug** + +This managed entity is used to send vendor-specific debug commands to the ONT and receive vendor-specific replies back for processing on the OLT. This allows for the remote debugging of an ONT that may not be accessible by any other means. The command format may have two modes, one being text and the other free format. In text format, both the command and reply are ASCII strings. In free format, the content and format of command and reply are vendor-specific. + +An ONT that supports remote debugging automatically creates an instance of this managed entity. It is not reported during a MIB upload. + +#### *Relationships* + +One instance of this managed entity is associated with the ONT managed entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Command format:** This attribute defines the format of the command and reply attributes. Value 0 defines ASCII string format, while 1 specifies free format. (R) (mandatory) (1 byte) + +**Command:** This attribute is used to send a command to the ONT. The format of the command is defined by the command format. If the format is ASCII string, the command should be null terminated unless the string is 25 bytes long. The action of setting this attribute should trigger the ONT to discard any previous command reply information and execute the current debugging command. (W) (mandatory) (25 bytes) + +**Reply table:** This attribute is used to pass reply information back to the OLT. Its format is defined by the command format attribute. The get, get next action sequence must be used with this attribute, since its size is unspecified. On a get action, the ONT returns the size of the reply (per normal get next usage). If the size of the reply is unknown at the time of the get, the ONT returns the value 0xFFFF FFFF. The OLT then issues get next requests until the ONT is exhausted of data, whereupon the ONT returns a parameter error response. The OLT then terminates the get next process. (R) (mandatory) (N bytes) + +#### *Actions* + +#### **Get, get next, set** + +#### *Notifications* + +None. + +## **9.2 ANI management** + +Although the OLT maintains some of the PON-related managed entities and attributes via G.984.3 PLOAM messages, there is also information to be negotiated in OMCC. Therefore, the ONT autonomously creates at least one instance of each of the managed entities ANI-G and T-CONT. These ANI management MEs are included in a MIB upload. + +### **9.2.1 ANI-G** + +This managed entity organizes data associated with each access network interface supported by the ONT. The ONT automatically creates one instance of this managed entity for each PON physical port. + +#### *Relationships* + +An instance of this managed entity is associated with each instance of a physical PON interface. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Its value indicates the physical position of the PON IF. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID. (R) (mandatory) (2 bytes) + +**SR indication:** This Boolean attribute indicates the ONT's capability to report queue status for DBA. The value true means that status reporting is available for all T-CONTs that are associated with the ANI. (R) (mandatory) (1 byte) + +**Total T-CONT number:** This attribute indicates the total number of T-CONTs that can be supported on this ANI. (R) (mandatory) (2 bytes) + +**GEM block length:** This attribute specifies the reporting block size for GEM mode, in units of bytes. The value set by the OLT is used by all T-CONTs on this ANI. Upon ME instantiation, the ONT sets this attribute to 48. (R, W) (mandatory) (2 bytes) + +| | | | | | | | | | | | | +|---------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|--------------|---|----------------|---|----------------|---|-------------------|---|----------------------------------------| +| Piggyback DBA reporting: |

This attribute indicates the ONT's piggyback DBA reporting format capabilities. [ITU-T G.984.3] defines three possible piggyback reporting modes. For reporting mode 0, the single field is the entire report. For reporting mode 1, the DBA report is two fields long. For reporting mode 2, the DBA report is four fields long. Mode 0 is mandatory for ONTs that utilize the piggyback DBA reporting method; modes 1 and 2 are optional. The following coding indicates the ONT's piggyback DBA reporting mode capabilities:

0Mode 0 only.
1Modes 0 and 1.
2Modes 0 and 2.
3Modes 0, 1 and 2.
4Piggyback DBA reporting not supported.

(R) (mandatory) (1 byte)

| 0 | Mode 0 only. | 1 | Modes 0 and 1. | 2 | Modes 0 and 2. | 3 | Modes 0, 1 and 2. | 4 | Piggyback DBA reporting not supported. | +| 0 | Mode 0 only. | | | | | | | | | | | +| 1 | Modes 0 and 1. | | | | | | | | | | | +| 2 | Modes 0 and 2. | | | | | | | | | | | +| 3 | Modes 0, 1 and 2. | | | | | | | | | | | +| 4 | Piggyback DBA reporting not supported. | | | | | | | | | | | +| Whole ONT DBA reporting: |

This attribute indicates that the ONT supports whole ONT DBA reporting (1) as specified in [ITU-T G.984.3], or that it does not (0). (R) (mandatory) (1 byte)

| | | | | | | | | | | +| SF threshold: |

This attribute specifies the downstream BER threshold to detect the SFi/SF alarm. When this value is y, the BER threshold is 10^{-y}. Valid values are 3..8. Upon ME instantiation, the ONT sets this attribute to 5. (R, W) (mandatory) (1 byte)

| | | | | | | | | | | +| SD threshold: |

This attribute specifies the downstream BER threshold to detect the SDi/SD alarm. When this value is x, the BER threshold for SDi/SD is 10^{-x}. Valid values are 4..10. The SD threshold must be lower than the SF threshold; that is, x > y. Upon ME instantiation, the ONT sets this attribute to 9. (R, W) (mandatory) (1 byte)

| | | | | | | | | | | +| ARC: | See clause I.1.8. (R, W) (optional) (1 byte) | | | | | | | | | | | +| ARC interval: | See clause I.1.8. (R, W) (optional) (1 byte) | | | | | | | | | | | +| Optical signal level: |

This attribute reports the current measurement of total optical signal level at 1490 nm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (R) (optional) (2 bytes)

| | | | | | | | | | | +| Lower optical threshold: |

This attribute specifies the optical level the ONT uses to declare the 1490 nm low received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the ONT's internal policy. (R, W) (optional) (1 byte)

| | | | | | | | | | | +| Upper optical threshold: |

This attribute specifies the optical level the ONT uses to declare the 1490 nm high received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the ONT's internal policy. (R, W) (optional) (1 byte)

| | | | | | | | | | | + +**ONT response time:** This attribute indicates actual ONT response time recorded by ONT. The range of this attribute should be in the range described in [ITU-T G.984.3], which is 34..36 microseconds. The unit is nanoseconds; however, the accuracy is likely to be more coarse. Furthermore, the value may change from one ranging cycle to the next. Valid values are: + +0 null, function not supported. +34000 to 36000 response time in nanoseconds. + +All other values reserved. + +(R) (optional) (2 bytes) + +**Transmit optical level:** This attribute reports the current measurement of optical transmit power level. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (R) (optional) (2 bytes) + +**Lower transmit power threshold:** This attribute specifies the transmit power level the ONT uses to declare the low transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value -63.5 (0x81) selects the ONT's internal policy. (R, W) (optional) (1 byte) + +**Upper transmit power threshold:** This attribute specifies the transmit power level the ONT uses to declare the high transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value -63.5 (0x81) selects the ONT's internal policy. (R, W) (optional) (1 byte) + +#### Actions + +#### Get, set + +**Test:** Test the ANI-G. The test action can be used to perform optical line supervision tests; refer to Appendix II. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------------| +| 1..7 | N/A | | +| 8 | ARC | Alarm reporting control cancellation | +| 9..12 | N/A | | +| 13..16 | Reserved | | + +##### Alarm + +| Number | Alarm | Description | +|--------|-----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Low received optical power | Received 1490 nm optical power below threshold | +| 1 | High received optical power | Received 1490 nm optical power above threshold | +| 2 | SF | Bit error-based signal fail. Industry practice normally expects the BER to improve by at least an order of magnitude before clearing the alarm. | +| 3 | SD | Bit error-based signal degrade. Industry practice normally expects the BER to improve by at least an order of magnitude before clearing the alarm. | +| 4 | Low transmit optical power | Transmit optical power below lower threshold | + +##### Alarm + +| Number | Alarm | Description | +|----------|-----------------------------|------------------------------------------------------------------------------------| +| 5 | High transmit optical power | Transmit optical power above upper threshold | +| 6 | Laser bias current | Laser bias current above threshold determined by vendor; laser end of life pending | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +**Test result:** The ONT may report a test result autonomously if it performs self test functions autonomously. + +### 9.2.2 T-CONT + +An instance of the traffic container managed entity T-CONT represents a logical connection group associated with a PLOAM layer alloc-id. A T-CONT can accommodate GEM packets in priority queues or traffic schedulers that exist in the GEM layer. + +The ONT autonomously creates instances of this ME. The OLT can discover the number of T-CONT instances via the ANI-G ME. When the ONT's MIB is reset or created for the first time, all supported T-CONTs are created. The OLT provisions allocation-IDs to the ONT via the PLOAM channel. The OLT must then set the alloc-id attributes in the T-CONTs that it wants to activate for user traffic, to create the appropriate association between the allocation ID set in the PLOAM channel and the T-CONT in the OMCI. Once that association is created, the mode indicator attribute assumes the mode specified in the PLOAM channel. Note that there should be a one-to-one relationship between allocation IDs and T-CONT MEs, and the connection of multiple T-CONTs to a single allocation ID is undefined. + +Note that the first allocation ID that is granted via the PLOAM channel is defined to be the default alloc-id, and this alloc-id is the one that is used to carry the OMCC. The default alloc-id can also be used to carry user traffic, and hence can be set into one of the T-CONT MEs. However, this OMCI relationship only pertains to the user traffic, and the OMCC relationship is unaffected. It can also be true that the OMCC is not contained in any T-CONT ME construct; rather, that the OMCC remains outside of the OMCI, and the OMCI is not used to manage the OMCC in any way. The handling of the multiplexing of OMCC and user data is discussed in clause 11.3.3. + +#### *Relationships* + +One or more instances of this managed entity are associated with an instance of a circuit pack that supports a PON IF function, or the ONT-G itself. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical capability that realizes the T-CONT. It may be represented as 0xSSBB, where SS indicates the slot id that contains this T-CONT (0 for the ONT as a whole), and BB is the T-CONT id, numbered by the ONT itself. T-CONTs are numbered in ascending order, with range 0..255 in each slot. (R) (mandatory) (2 bytes) +- Alloc-id:** This attribute links the T-CONT with the alloc-id assigned by the OLT in the assign\_allocID PLOAM message. Legal values range from 0 to 0x0FFF, with some values having special meaning as defined in [ITU-T G.984.3]. Prior to setting of this attribute assignment by the OLT (via the OMCI channel), this attribute has default value 0x00FF. (R, W) (mandatory) (2 bytes) +- Mode indicator:** This attribute indicates whether the T-CONT operates in ATM mode (0) or GEM mode (1), as set via the PLOAM channel. ATM mode is deprecated; this attribute should always have the value 1. (R) (mandatory) (1 byte) +- Policy:** This attribute indicates the T-CONT's traffic scheduling policy. Valid values: +- | | | +|---|------------------------------| +| 0 | Null. | +| 1 | HOL – Head of line queueing. | +| 2 | WRR – Weighted round robin. | +- (R) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.2.3 GEM port network CTP** + +This managed entity represents the termination of a GEM port on an ONT. This managed entity aggregates connectivity functionality from the network view and alarms from the network element view as well as artefacts from trails. + +Instances of the GEM port network CTP managed entity are created and deleted by the OLT. An instance of GEM port network CTP can be deleted only when no GEM interworking termination point or GEM port PM history data is associated with it. It is the responsibility of the OLT to make sure that the GEM port network CTP meets this condition. + +When a GEM port network CTP is created, its encryption state is by default not encrypted. If the OLT wishes to configure the GEM port to use encryption, then the appropriate PLOAM message must be sent. This applies equally to new CTPs or to CTPs that are re-created after a MIB reset. + +#### *Relationships* + +An instance of the GEM port network CTP managed entity may be associated with an instance of the T-CONT and GEM interworking termination point managed entities. + +#### Attributes + +| | | +|-------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| Port id value: | This attribute is the port id of the GEM port associated with this CTP. (R, W, Set-by-create) (mandatory) (2 bytes) | +| T-CONT pointer: | This attribute points to a T-CONT instance. (R, W, Set-by-create) (mandatory) (2 bytes)
NOTE – In previous versions of this Recommendation, this attribute was described as pointing to a PON TC adaptor-G. However, the latter ME had no purpose, de facto , and has been omitted from this version. The instance identifier of the PON TC adaptor was always defined to be identical to that of its corresponding T-CONT, so this documentation change has no practical effect on pre-existing implementations. | +| Direction: | This attribute specifies whether the GEM port is used for UNI-to-ANI (1), ANI-to-UNI (2), or bidirectional (3) connection. (R, W, Set-by-create) (mandatory) (1 byte) | +| Traffic management pointer for upstream: | If the traffic management option attribute in the ONT-G ME is 0 (priority controlled), this pointer specifies the priority queue-G ME serving this GEM port network CTP. If the traffic management option attribute is 1 (rate controlled), this attribute redundantly points to the T-CONT serving this GEM port network CTP. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Traffic descriptor profile pointer: | This attribute points to the instance of the GEM traffic descriptor managed entity that contains the traffic parameters used for this GEM port network CTP ME. This attribute is used when the traffic management option attribute in the ONT-G ME is 1 (rate controlled). (R, W, Set-by-create) (optional) (2 bytes)
See also Appendix III. | +| UNI counter: | This attribute reports the number of instances of UNI-G managed entity associated with this GEM port network CTP. (R) (optional) (1 byte) | +| Priority queue pointer for downstream: | This attribute points to the instance of the priority queue-G used for this GEM port network CTP in the downstream direction. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Encryption state: | This attribute indicates the current state of the GEM port network CTP's encryption. Legal values are defined to be the same as those of the security mode attribute of the ONT2-G, with the exception that attribute value 0 indicates an unencrypted GEM port. (R) (optional) (1 byte) | + +#### Actions + +**Create, delete, get, set** + +#### Notifications + +##### Alarm + +| Number | Alarm | Description | +|----------|-------------------------------|---------------------------------------------------------------------------------------------------------------------------| +| 0..4 | Reserved | | +| 5 | End-to-end loss of continuity | Loss of continuity can be detected when the GEM port network CTP supports a GEM interworking termination point (optional) | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.2.4 GEM interworking termination point + +An instance of this managed entity represents a point in the ONT where the interworking of a service (e.g., CES, IP) or underlying physical infrastructure (e.g., n x DS0, DS1, DS3, E3, Ethernet) to GEM layer takes place. At this point, GEM packets are generated from a bit stream (e.g., Ethernet) or a bit stream is reconstructed from GEM packets. + +Instances of this managed entity are created and deleted by the OLT. + +#### Relationships + +One instance of this managed entity exists for each transformation of a data stream into GEM packets and vice versa. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. It must be unique over all interworking VCC termination point and GEM interworking termination point MEs. (R, Set-by-create) (mandatory) (2 bytes) + +**GEM port network CTP connectivity pointer:** This attribute points to an instance of the GEM port network CTP. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interworking option:** This attribute identifies the type of non-GEM function that is being interworked. The options are: + +- 0 Unstructured TDM. +- 1 MAC bridge LAN. +- 2 Reserved for future use. +- 3 IP data service. +- 4 Video return path. +- 5 802.1p mapper. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**Service profile pointer:** This attribute points to an instance of a service profile, such as: + +- CES service profile-G if interworking option = 0 +- MAC bridge service profile if interworking option = 1 +- IP router service profile if interworking option = 3 +- Video return path service profile if interworking option = 4 +- 802.1p mapper service profile if interworking option = 5 + +(R, W, Set-by-create) (mandatory) (2 bytes) + +##### **Interworking termination point pointer:** + +This attribute is used for circuit emulation service and 802.1p mapper service without a MAC bridge. Depending on the service provided, it points to the associated instance of the following managed entities: + +- Physical path termination point CES UNI. +- Logical N × 64 kbit/s sub-port connection termination point. +- Physical path termination point Ethernet UNI. +- TU CTP. + +In all other GEM services, the relationship between the related service termination point and this GEM interworking termination point is derived from other managed entity relations; this attribute is set to 0 and not used. (R, W, Set-by-create) (mandatory) (2 bytes) + +##### **PPTP counter:** + +This value reports the number of PPTP managed entity instances associated with this GEM interworking termination point. (R) (optional) (1 byte) + +##### **Operational state:** + +This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +##### **GAL profile pointer:** + +This attribute points to an instance of the GAL profile. The relationship between the interworking option and the related GAL profile is: + +| Interworking option | GAL profile type | +|---------------------|--------------------------------------------| +| 0 | GAL TDM profile | +| 1 | GAL Ethernet profile | +| 2 | Reserved for future use | +| 3 | GAL Ethernet profile for data service | +| 4 | GAL Ethernet profile for video return path | +| 5 | GAL Ethernet profile for 802.1p mapper | + +(R, W, Set-by-create) (mandatory) (2 bytes) + +##### **GAL loopback configuration:** + +This attribute sets the loopback configuration when using GEM mode: + +- 0 No loopback. +- 1 Loopback of downstream traffic after GAL. + +The default value of this attribute is 0. (R, W) (mandatory) (1 byte) + +#### *Actions* + +**Create, delete, get, set** + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..5 | N/A | | +| 6 | Op state | Operational state change | +| 7..8 | N/A | | +| 9..16 | Reserved | | + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|----------------------------| +| 0 | GFSA | GEM frame starvation alarm | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.2.5 Multicast GEM interworking termination point + +An instance of this managed entity represents a point in the ONT where a multicast service interworks with the GEM layer. At this point, a multicast bit stream is reconstructed from GEM packets. + +Instances of this managed entity are created and deleted by the OLT. + +#### Multicast interworking GEM modes of operation + +The default multicast operation of the PON is where all the multicast content streams are placed in one PON layer connection (GEM port). This connection is then specified in the first entry of the multicast address table. This single entry also specifies an all-inclusive IP multicast address range (e.g., 224.0.0.0 to 239.255.255.255). The ONT then filters the traffic based on either Ethernet MAC addresses or IP addresses. The GEM port network CTP ME contains the GEM port-ID that supports all multicast connections. + +An optional multicast operation is where groups of one or more multicast content streams are carried over individual PON layer connections, i.e., on separate GEM ports, but terminate on a single multicast GEM interworking termination point. In this case, the OLT sets as many table entries as desired for the multicast control system. The ONT can initially filter groups based on PON layer address (GEM port). In a subsequent step, the ONT can also filter based on higher-layer addresses. In this case, the OLT need create only one instance of the GEM port network CTP ME. Though this GEM port network CTP ME cites only one GEM port-ID, the ONT should regard this ME as the representative of all multicast GEM connections served by the multicast GEM interworking TP. The traffic descriptors, priority queues, and performance management features for all multicast connections are integrated into the single GEM port network CTP ME. + +Several multicast GEM interworking termination points can exist, each linked to separate bridge ports or mappers to serve different communities of interest in a complex ONU. + +#### Discovery of multicast support + +The OLT uses the multicast GEM IW TP entity as the means to discover the ONT's multicast capability. This entity is mandatory if multicasting is supported by the ONT. If the OLT attempts to create this entity on an ONT that does not support multicast, the create command fails; likewise with attempts to create a multicast address table with more than a single entry or to create multiple GEM interworking termination points. + +This managed entity is defined by similarity to the unicast GEM interworking termination point, and a number of its attributes are not meaningful in a multicast context. These attributes are set to 0 and not used, as indicated below. + +#### *Relationships* + +An instance of this managed entity exists for each occurrence of transformation of GEM packets into a multicast data stream. + +#### *Attributes* + +| | | +|---------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. The value 0xFFFF is reserved. (R, Set-by-create) (mandatory) (2 bytes) | +| GEM port network CTP connectivity pointer: | This attribute points to an instance of the GEM port network CTP that is associated with this multicast GEM interworking termination point. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Interworking option: | This attribute identifies the type of non-GEM function that is being interworked. The option can be:
0 This value is a "no-op" or "do not care". It should be used when the multicast GEM IW TP is associated with several functions of different types. It can optionally be used in all cases, since the necessary information is available elsewhere. The previous codepoints are retained for backward compatibility.
1 MAC bridge LAN.
3 IP router.
5 802.1p mapper.
(R, W, Set-by-create) (mandatory) (1 byte) | +| Service profile pointer: | This attribute is set to 0 and not used. For backward compatibility, it may also be set to point to a MAC bridge service profile, IP router service profile or 802.1P mapper service profile. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Interworking termination point pointer: | This attribute is set to 0 and not used. (R, W, Set-by-create) (mandatory) (2 bytes) | +| PPTP counter: | This attribute represents the number of instances of PPTP managed entities associated with this instance of the multicast GEM interworking termination point. This attribute conveys no information that is not available elsewhere; it may be set to 0xFF and not used. (R) (optional) (1 byte) | +| Operational state: | This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) | +| GAL profile pointer: | This attribute is set to 0 and not used. For backward compatibility, it may also be set to point to a GAL Ethernet profile. (R, W, Set-by-create) (mandatory) (2 bytes) | +| GAL loopback configuration: | This attribute is set to 0 and not used. (R, W, Set-by-create) (mandatory) (1 byte) | + +**Multicast address table:** This attribute maps IP multicast addresses to PON layer addresses. Each entry contains: + +- GEM port-ID 2 bytes +- Secondary index 2 bytes +- IP multicast address range start 4 bytes +- IP multicast address range stop 4 bytes + +The first four bytes of each entry are treated as the index of the list. The secondary index allows the table to contain more than a single range for a given GEM port. + +A set action to a particular value overwrites any existing entry with the same first four bytes. If the last eight bytes of a set command are all zero, that entry is deleted from the list, as the all-zero IP address is not valid. + +One OMCI set message can convey up to two table entries. However, OMCI does not provide robust exception handling when more than one entry is included in a set command, and multiple entries per set operation are not recommended. + +(R, W) (mandatory) (12N bytes, where N is the number of entries in the list) + +#### *Actions* + +**Create, delete, get, get next, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..5 | N/A | | +| 6 | Op state | Operational state change | +| 7..9 | N/A | | +| 10..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|----------|------------------------|----------------------------| +| 0 | GFSA | GEM frame starvation alarm | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.2.6 GEM port performance monitoring history data** + +This managed entity collects performance monitoring data associated with a GEM port network CTP. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the GEM port network CTP managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the GEM port network CTP. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Lost packets:** This attribute counts background GEM frame loss. It does not distinguish between packets lost because of header bit errors or buffer overflows; it records only loss of information. (R) (mandatory) (4 bytes) +- Misinserted packets:** This attribute counts GEM frames misrouted to this GEM port. (R) (mandatory) (4 bytes) +- Received packets:** This attribute counts GEM frames that were received correctly at the monitored GEM port. (R) (mandatory) (5 bytes) +- Received blocks:** This attribute counts GEM blocks that were received correctly at the monitored GEM port. (R) (mandatory) (5 bytes) +- Transmitted blocks:** This attribute counts GEM blocks originated by the transmitting end point (i.e., backward reporting is assumed). (R) (mandatory) (5 bytes) +- Impaired blocks:** This severely errored data block counter is incremented whenever one of the following events takes place: the number of misinserted packets reaches its threshold, the number of bipolar violations reaches its threshold, or the number of lost packets reaches its threshold. Threshold values are based on vendor-operator negotiation. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|---------------|---------------------------------|-------------------------------------------| +| 0 | Lost packets | 1 | +| 1 | Misinserted packets | 2 | +| 2 | Impaired blocks | 3 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.2.7 GAL Ethernet profile + +This managed entity organizes data that describes the GTC adaptation layer processing functions of the ONT for Ethernet services. It is used with the GEM interworking termination point managed entity. + +Instances of this managed entity are created and deleted on request of the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the GEM interworking termination point managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) +- Maximum GEM payload size:** This attribute defines the maximum payload size generated in the associated GEM interworking termination point managed entity. (R, W, Set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +#### **Create, delete, get, set** + +#### *Notifications* + +None. + +### 9.2.8 GAL Ethernet performance monitoring history data + +This managed entity collects performance monitoring data associated with a GEM interworking termination point when the GEM layer provides Ethernet service. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the GEM interworking termination point managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the GEM interworking TP. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Discarded frames:** This attribute counts the number of downstream GEM frames discarded for any reason (erroneous FCS, too long, buffer overflow, etc.). (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|---------------|---------------------------------|-------------------------------------------| +| 0 | Discarded frames | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.2.9 GAL TDM profile** + +This managed entity organizes data that describes the GTC adaptation layer processing functions of the ONT for TDM services. [ITU-T G.984.3] explains that the GEM adaptation layer generates a 125 µs GEM frame that accommodates TDM traffic. The length of the TDM partition in the GEM frame depends on the TDM UNI bit rate. The clock recovery function and structured data transfer function are not necessary because the GEM is terminated in the PON section. + +The receiver of the GEM adaptation layer should check for loss of GEM frame once every 125 µs. + +This managed entity is created and deleted on request of the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the GEM interworking termination point managed entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**GEM frame loss integration period:** This attribute is the GEM frame loss integration period in milliseconds. If GEM frame loss persists for this period, the GEM interworking termination point managed entity associated with this entity generates a GEM frame starvation alarm. (R, W, Set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None + +### **9.2.10 GAL TDM performance monitoring history data** + +This managed entity collects performance monitoring data from segmentation and reassembly (SAR) and convergence sublayer (CS) levels of a GEM interworking termination point that supports GAL TDM. + +Instances of this managed entity are created and deleted on request of the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +One instance of this managed entity may exist for each instance of the GEM interworking termination point managed entity that represents GAL TDM functions. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the GEM interworking termination point ME. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- GEM frame loss:** This attribute counts the number of lost GEM frames. It records the number of GEM frames detected as lost in the network prior to the destination interworking function GTC adaptation layer processing. (R) (mandatory) (4 bytes) +- Buffer underflows:** This attribute counts the number of times the reassembly buffer underflows. In the case of continuous underflow caused by a loss of GEM frame flow, a single buffer underflow should be counted. If the interworking function is implemented with multiple buffers, such as a cell level buffer and a bit level buffer, then either buffer underflow causes this count to be incremented. (R) (mandatory) (4 bytes) +- Buffer overflows:** This attribute counts the number of times the reassembly buffer overflows. If the interworking function is implemented with multiple buffers, such as a cell level buffer and a bit level buffer, then either buffer overflow causes this count to be incremented. (R) (mandatory) (4 bytes) + +#### Actions + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | GEM frame loss | 1 | +| 1 | Buffer underflows | 2 | +| 2 | Buffer overflows | 3 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.2.11 FEC performance monitoring history data + +This managed entity collects performance monitoring data associated with FEC counters. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the ANI-G managed entity. + +#### *Attributes* + +| | | +|----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the ANI-G. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Corrected bytes: | This attribute counts the number of bytes that were corrected by the FEC function. (R) (mandatory) (4 bytes) | +| Corrected code words: | This attribute counts the code words that were corrected by the FEC function. (R) (mandatory) (4 bytes) | +| Uncorrectable code words: | This attribute counts the code words that were not corrected by the FEC function. (R) (mandatory) (4 bytes) | +| Total code words: | This attribute counts the total received code words. (R) (mandatory) (4 bytes) | +| FEC seconds: | This attribute counts seconds during which there was a forward error correction anomaly. (R) (mandatory) (2 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Corrected bytes | 1 | +| 1 | Corrected code words | 2 | +| 2 | Uncorrectable code words | 3 | +| 3 | Reserved | | +| 4 | FEC seconds | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## 9.3 Layer 2 data services + +As outlined in Figure 9.3-1, this clause describes managed entities that support layer 2 services, independent of the exact nature of the interface (e.g., Ethernet, MoCA, xDSL). Possible interfaces are described in their own clauses. + +![Figure 9.3-1 – Managed entities that support layer 2. A complex block diagram showing relationships between various network management entities. Entities include MAC bridge service profile, MAC bridge configuration data, 802.1p mapper service profile, MAC bridge PM history data, MAC bridge port PM history data, MAC bridge port designation data, VLAN tagging operation config data, MAC bridge port filter table data, Extended VLAN tagging operation config data, MAC bridge port filter preassign table, Dot1x port extension package, MAC bridge port bridge table data, Dot1x PM history data, VLAN tagging filter data, Dot1x configuration profile, Radius PM history data, Multicast subscriber config info, Multicast operations profile, Multicast subscriber monitor, Dot1 rate limiter, Dotlag chassis-mgt info, Dotlag maintenance domain, Dotlag default MD level, Dotlag MEP CCM database, Dotlag maintenance association, Dotlag CFM stack, Dotlag MEP status, and Dotlag MEP. Relationships are shown via arrows with labels like 'Pointed to by:', 'Implicit links:', 'Points to:', and 'Linked to:', often accompanied by multiplicity indicators like 'N' or '1'.](d9ea7e6c55ac790700d27c96ba7f66a3_img.jpg) + +The diagram illustrates the managed entities for Layer 2 services and their interrelationships: + +- 9.3.1: MAC bridge service profile** is pointed to by GEM interworking TP and Multicast GEM interworking TP. It has an 'N' relationship with **9.3.2: MAC bridge configuration data** and **9.3.4: MAC bridge port config data**. +- 9.3.10: 802.1p mapper service profile** connects to Common TP and Interwork TP 0..7. +- 9.3.3: MAC bridge PM history data** and **9.3.9: MAC bridge port PM history data** point to **9.3.4: MAC bridge port config data**. +- 9.3.4: MAC bridge port config data** is pointed to by Extended VLAN tagging operation config data, IP port config data, and VLAN tagging operation config data. It has 'N' relationships with **9.3.5: MAC bridge port designation data**, **9.3.6: MAC bridge port filter table data**, **9.3.7: MAC bridge port filter preassign table**, **9.3.8: MAC bridge port bridge table data**, **9.3.11: VLAN tagging filter data**, **9.3.12: VLAN tagging operation config data**, **9.3.13: Extended VLAN tagging operation config data**, **9.3.14: Dot1x port extension package**, **9.3.15: Dot1x configuration profile**, **9.3.16: Dot1x PM history data**, **9.3.17: Radius PM history data**, and **9.3.28: Multicast subscriber config info**. +- 9.3.11: VLAN tagging filter data** points to TP, Outbound TD, and Inbound TD. +- 9.3.12: VLAN tagging operation config data** connects to UNI, IW TP or IP host. +- 9.3.13: Extended VLAN tagging operation config data** connects to UNI, IW TP or IP host. +- 9.3.14: Dot1x port extension package** connects to UNI. +- 9.3.16: Dot1x PM history data** connects to UNI. +- 9.3.28: Multicast subscriber config info** is pointed to by MAC bridge port config data and 802.1p mapper service profile. It has an 'N' relationship with **9.3.27: Multicast operations profile**. +- 9.3.29: Multicast subscriber monitor** points to MAC bridge port config data and 802.1p mapper service profile. +- 9.3.18: Dot1 rate limiter** points to MAC bridge config data or 802.1p mapper service profile. +- 9.3.26: Dotlag chassis-mgt info**, **9.3.19: Dotlag maintenance domain**, and **9.3.21: Dotlag default MD level** are linked to MAC bridge service profile or 802.1p mapper service profile. +- 9.3.24: Dotlag MEP CCM database** points to **9.3.20: Dotlag maintenance association**. +- 9.3.20: Dotlag maintenance association** has an 'N' relationship with **9.3.19: Dotlag maintenance domain** and a '1' relationship with **9.3.22: Dotlag MEP**. +- 9.3.25: Dotlag CFM stack** is linked to MAC bridge service profile or 802.1p mapper service profile. +- 9.3.23: Dotlag MEP status** points to **9.3.22: Dotlag MEP**. +- 9.3.22: Dotlag MEP** points to MAC bridge port config data or 802.1p mapper service profile. + +Figure 9.3-1 – Managed entities that support layer 2. A complex block diagram showing relationships between various network management entities. Entities include MAC bridge service profile, MAC bridge configuration data, 802.1p mapper service profile, MAC bridge PM history data, MAC bridge port PM history data, MAC bridge port designation data, VLAN tagging operation config data, MAC bridge port filter table data, Extended VLAN tagging operation config data, MAC bridge port filter preassign table, Dot1x port extension package, MAC bridge port bridge table data, Dot1x PM history data, VLAN tagging filter data, Dot1x configuration profile, Radius PM history data, Multicast subscriber config info, Multicast operations profile, Multicast subscriber monitor, Dot1 rate limiter, Dotlag chassis-mgt info, Dotlag maintenance domain, Dotlag default MD level, Dotlag MEP CCM database, Dotlag maintenance association, Dotlag CFM stack, Dotlag MEP status, and Dotlag MEP. Relationships are shown via arrows with labels like 'Pointed to by:', 'Implicit links:', 'Points to:', and 'Linked to:', often accompanied by multiplicity indicators like 'N' or '1'. + +G.984.4(08)\_F9.3-1 + +Figure 9.3-1 – Managed entities that support layer 2 + +### 9.3.1 MAC bridge service profile + +This managed entity models a MAC bridge in its entirety; any number of ports may then be associated with the bridge through pointers to the MAC bridge service profile managed entity. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +Bridge ports are modelled by MAC bridge port configuration data managed entities, any number of which can point to a MAC bridge service profile. The real-time status of the bridge is available from an implicitly linked MAC bridge configuration data ME. + +#### *Attributes* + +| | | +|-------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. The first byte is the slot id (defined in clause 9.1.5). If the UNI is integrated, this value is 0. The second byte is the bridge group id. (R, Set-by-create) (mandatory) (2 bytes) | +| Spanning tree ind: | The Boolean value true specifies that the spanning tree algorithm is enabled. The value false disables spanning tree. (R, W, Set-by-create) (mandatory) (1 byte) | +| Learning ind: | The Boolean value true specifies that bridge learning functions are enabled. The value false disables bridge learning. (R, W, Set-by-create) (mandatory) (1 byte) | +| Port bridging ind: | The Boolean value true specifies that bridging between UNI ports is enabled. The value false disables local bridging. (R, W, Set-by-create) (mandatory) (1 byte) | +| Priority: | This attribute specifies the bridge priority in the range 0..65535. The value of this attribute is copied to the bridge priority attribute of the associated MAC bridge configuration data managed entity. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Max age: | This attribute specifies the maximum age (in 256ths of a second) of received protocol information before its entry in the spanning tree listing is discarded. The range is 0x0600 to 0x2800 (6..40 seconds) in accordance with [IEEE 802.1D]. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Hello time: | This attribute specifies how often (in 256ths of a second) the bridge advertises its presence via hello packets while as a root or attempting to become a root. The range is 0x0100 to 0x0a00 (1..10 seconds) in accordance with [IEEE 802.1D]. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Forward delay: | This attribute specifies the forwarding delay (in 256ths of a second) when the bridge acts as the root. The range is 0x0400 to 0x1e00 (4..30 seconds) in accordance with [IEEE 802.1D]. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Unknown MAC address discard: | The Boolean value true specifies that MAC frames with unknown destination addresses be discarded. The value false specifies that such frames be forwarded to all allowed ports. (R, W, Set-by-create) (mandatory) (1 byte) | + +**MAC learning depth:** This attribute specifies the maximum number of UNI MAC addresses to be learned by the bridge. The default value 0 specifies that there is no administratively-imposed limit. (R, W, Set-by-create) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.2 MAC bridge configuration data** + +This managed entity organizes status data associated with a MAC bridge. The ONT automatically creates or deletes an instance of this managed entity upon the creation or deletion of a MAC bridge service profile. + +#### *Relationships* + +This managed entity is associated with one instance of a MAC bridge service profile. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge service profile. (R) (mandatory) (2 bytes) + +**Bridge MAC address:** This attribute indicates the MAC address used by the bridge. The ONT sets this attribute to the value programmed into the ONT. (R) (mandatory) (6 bytes) + +**Bridge priority:** This attribute reports the priority of the bridge. The ONT copies this attribute from the priority attribute of the associated MAC bridge service profile. The value of this attribute changes with updates to the MAC bridge service profile priority attribute. (R) (mandatory) (2 bytes) + +**Designated root:** This attribute identifies the bridge at the root of the spanning tree. It comprises bridge priority (2 bytes) and MAC address (6 bytes). (R) (mandatory) (8 bytes) + +**Root path cost:** This attribute reports the cost of the best path to the root as seen from the bridge. Upon ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (4 bytes) + +**Bridge port count:** This attribute records the number of ports linked to this bridge. (R) (mandatory) (1 byte) + +**Root port num:** This attribute contains the port number that has the lowest cost from the bridge to the root bridge. The value 0 means that this bridge is itself the root. Upon ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (2 bytes) + +**Hello time:** This attribute is the hello time received from the designated root, the interval (in 256ths of a second) between hello packets. Its range is 0x0100 to 0x0a00 (1..10 seconds) in accordance with [IEEE 802.1D]. (R) (optional) (2 bytes) + +**Forward delay:** This attribute is the forwarding delay time received from the designated root (in 256ths of a second). Its range is 0x0400 to 0x1e00 (4..30 seconds) in accordance with [IEEE 802.1D]. (R) (optional) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.3.3 MAC bridge performance monitoring history data** + +This managed entity collects performance monitoring data associated with a MAC bridge. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +This managed entity is associated with one instance of a MAC bridge service profile. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge service profile. (R, Set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Bridge learning entry discard count:** This attribute counts forwarding database entries that have been or would have been learned but were discarded or replaced due to lack of space in the database table. When used with the MAC learning depth attribute of the MAC bridge service profile, the bridge learning entry discard count may be particularly useful in detecting MAC spoofing attempts. (R) (mandatory) (4 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +##### **Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|----------------------------------------------------------------------------------------------------------------------------|-------------------------------|------------------------------------| +| 0 | Bridge learning entry discard | 1 | +| NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. | | | + +### 9.3.4 MAC bridge port configuration data + +This managed entity models a port on a MAC bridge. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity is linked to an instance of the MAC bridge service profile. Additional bridge port control capabilities are provided by implicitly linked instances of some or all of: + +- MAC bridge port filter table data. +- MAC bridge port filter preassign table. +- VLAN tagging filter data. +- Extended VLAN tagging operation config data. + +Real-time status of the bridge port is provided by implicitly linked instances of: + +- MAC bridge port designation data. +- MAC bridge port bridge table data. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Bridge id pointer:** This attribute points to an instance of the MAC bridge service profile. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Port num:** This attribute is the bridge port number. It must be unique among all ports associated with a particular MAC bridge service profile. (R, W, Set-by-create) (mandatory) (1 byte) + +**TP type:** This attribute identifies the type of termination point associated with this MAC bridge port. Valid values are: + +- 1 Physical path termination point Ethernet UNI. +- 2 Interworking VCC termination point. +- 3 802.1p mapper service profile. +- 4 IP host config data. +- 5 GEM interworking termination point. +- 6 Multicast GEM interworking termination point. +- 7 Physical path termination point xDSL UNI part 1. +- 8 Physical path termination point VDSL UNI. +- 9 Ethernet flow termination point. +- 10 Physical path termination point 802.11 UNI. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**TP pointer:** This attribute points to the termination point associated with this MAC bridge port. The TP type attribute indicates the type of the termination point; this attribute contains its instance identifier (ME ID). + +NOTE – When the TP type is VDSL or xDSL, the two most significant bits may be used to indicate a bearer channel. + +(R, W, Set-by-create) (mandatory) (2 bytes) + +| | | +|--------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Port priority: | This attribute denotes the priority of the port. The range is 0..255. (R, W, Set-by-create) (optional in GEM mode) (2 bytes) | +| Port path cost: | This attribute specifies the contribution of the port to the path cost toward the spanning tree root bridge. The range is 1..65535. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Port spanning tree ind: | The Boolean value true enables STP LAN topology change detection at this port. The value false disables topology change detection. (R, W, Set-by-create) (mandatory) (1 byte) | +| Encapsulation method: | This attribute is not used. If it is present, it should be set to 1. (R, W, Set-by-create) (optional) (1 byte) | +| LAN FCS ind: | This attribute indicates whether frame check sequence bytes are forwarded (0) or discarded (1). It is not expected to be needed in G-PON applications, but is retained for backward compatibility. The setting applies in both directions of transmission, and applies regardless of encapsulation method, but it is meaningful only for ports on the ANI side of the MAC bridge. The default value of this attribute is 0. (R, W, Set-by-create) (1 byte) (optional) | +| Port MAC address: | If the termination point associated with this port has a MAC address, this attribute specifies it. (R) (optional) (6 bytes) | +| Outbound TD pointer: | This attribute points to a GEM traffic descriptor that limits the traffic rate leaving the MAC bridge. (R, W) (optional) (2 bytes) | +| Inbound TD pointer: | This attribute points to a GEM traffic descriptor that limits the traffic rate entering the MAC bridge. (R, W) (optional) (2 bytes) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.5 MAC bridge port designation data** + +This managed entity records data associated with a bridge port. The ONT automatically creates or deletes an instance of this managed entity upon the creation or deletion of a MAC bridge port configuration data ME. + +#### *Relationships* + +An instance of this managed entity is associated with one MAC bridge port configuration data ME. + +#### *Attributes* + +| | | +|---------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data. (R) (mandatory) (2 bytes) | +|---------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| + +##### **Designated bridge root cost port:** + +This attribute contains the designated root, designated cost, designated bridge and designated port, which are some of the outputs of the *read port parameters* operation defined in clause 14.8.2.1 of [IEEE 802.1D]: + +- Identifier of the designated bridge for the port's segment (8 bytes). +- Bridge identifier of the root transmitted by the designated bridge for the segment (8 bytes). +- Port number of the designated port on the designated bridge considered to be part of this port's segment (4 bytes). +- Path cost contribution of the designated port to this port's segment (4 bytes). + +Upon ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (24 bytes) + +##### **Port state:** + +This attribute provides status information on the port. Valid values include: + +- 0 Disabled. +- 1 Listening. +- 2 Learning. +- 3 Forwarding. +- 4 Blocking. +- 5 Linkdown. +- 6 Stp\_off. + +in accordance with [IEEE 802.1D]. (R) (mandatory) (1 byte) + +NOTE – The value *linkdown* is introduced to denote the port status when the Ethernet link state is down. This value distinguishes the case where Ethernet is physically down from the case where Ethernet is administratively down, the latter being denoted by *disabled*. + +The value *stp\_off* is introduced to denote the port status where spanning tree protocol is disabled by setting the port spanning tree ind attribute of the MAC bridge port configuration data to false, and the Ethernet link state is up. This value distinguishes whether or not frame forwarding is under control of STP. + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.3.6 MAC bridge port filter table data** + +This managed entity organizes data associated with a bridge port. The ONT automatically creates or deletes an instance of this managed entity upon the creation or deletion of a MAC bridge port configuration data managed entity. + +NOTE – The OLT should disable learning mode in the MAC bridge service profile before writing to the MAC filter table. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a MAC bridge port configuration data managed entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +**MAC filter table:** This attribute lists MAC destination addresses associated with the bridge port, each with an allow/disallow forwarding indicator for traffic flowing out of the bridge port. In this way, the upstream traffic is filtered on the ANI-side bridge ports, and the downstream traffic is filtered on the UNI-side bridge ports. Each entry contains: + +- The entry number, an index into this attribute list (1 byte). +- Filter byte (1 byte). +- MAC address (6 bytes). + +The bits of the filter byte are assigned as follows: + +| Bit | Name | Setting | +|-------------------|--------------------|-----------------------------------------------------------| +| 1 (LSB) | Filter/forward | 0: forward
1: filter | +| 2..7 | Reserved | 0 | +| 8 | Add/remove | 0: remove this entry (set operation)
1: add this entry | + +Upon ME instantiation, the ONT sets this attribute to an empty table. + +One OMCI set message can convey a maximum of three table entries. However, OMCI does not provide robust exception handling when more than one entry is included in a set command, and multiple entries per set operation are not recommended. + +(R, W) (mandatory) (8N bytes, where N is the number of entries in the list) + +#### *Actions* + +#### **Get, get next, set** + +#### *Notifications* + +None. + +### **9.3.7 MAC bridge port filter preassign table** + +This managed entity provides an alternate approach to address filtering from that supported through MAC bridge port filter table data. This alternate approach is useful when all groups of addresses are stored beforehand in the ONT, and this managed entity designates which groups are valid or invalid for filtering. On a circuit pack in which all groups of addresses are preassigned and stored locally, the ONT creates or deletes an instance of this managed entity automatically upon creation or deletion of a MAC bridge port configuration data ME. + +#### Relationships + +An instance of this managed entity is associated with an instance of a MAC bridge port configuration data managed entity. + +##### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +The following ten attributes have similar definitions. Each permits the OLT to specify whether MAC addresses or Ethertypes of the named type are forwarded (0) or filtered (1). In each case, the initial value of the attribute is 0. + +| # | Protocol | MAC address | Ethertype | Standard | +|----|-------------------------------|----------------------------------------------------------------|-------------------|-------------------| +| 1 | IPv4 multicast | 01.00.5E.00.00.00 –
01.00.5E.7F.FF.FF | – | [b-IETF RFC 1700] | +| 2 | IPv6 multicast | 33.33.00.00.00.00 –
33.33.FF.FF.FF.FF | – | [b-IETF RFC 2464] | +| 3 | IPv4 broadcast | FF.FF.FF.FF.FF.FF | 0x0800 | [b-IETF RFC 1700] | +| 4 | RARP | FF.FF.FF.FF.FF.FF | 0x8035 | [b-IETF RFC 1700] | +| 5 | IPX | FF.FF.FF.FF.FF.FF | 0x8137 | [b-IETF RFC 1700] | +| | | 09.00.1B.FF.FF.FF,
09.00.4E.00.00.02 | – | | +| 6 | NetBEUI | 03.00.00.00.00.01 | – | | +| 7 | AppleTalk | FF.FF.FF.FF.FF.FF | 0x809B,
0x80F3 | [b-IETF RFC 1700] | +| | | 09.00.07.00.00.00 –
09.00.07.00.00.FC,
09.00.07.FF.FF.FF | – | | +| 8 | Bridge management information | 01.80.C2.00.00.00 –
01.80.C2.00.00.FF | – | [IEEE 802.1D] | +| 9 | ARP | FF.FF.FF.FF.FF.FF | 0x0806 | [b-IETF RFC 1700] | +| 10 | PPPoE broadcast | FF.FF.FF.FF.FF.FF | 0x8863 | [b-IETF RFC 2516] | + +**IPv4 multicast filtering:** (R, W) (mandatory) (1 byte) + +**IPv6 multicast filtering:** (R, W) (mandatory) (1 byte) + +**IPv4 broadcast filtering:** (R, W) (mandatory) (1 byte) + +**RARP filtering:** (R, W) (mandatory) (1 byte) + +**IPX filtering:** (R, W) (mandatory) (1 byte) + +**NetBEUI filtering:** (R, W) (mandatory) (1 byte) + +**AppleTalk filtering:** (R, W) (mandatory) (1 byte) + +**Bridge management information** (R, W) (mandatory) (1 byte) + +##### **filtering:** + +Note that some MAC addresses should not be handled, considering the following rules of [IEEE 802.1D]: + +- 1 Addresses from 01.80.C2.00.00.00 to 01.80.C2.00.00.0F are reserved. +- 2 Addresses from 01.80.C2.00.00.20 to 01.80.C2.00.02.0F are used for GARP application addresses. + +**ARP filtering:** (R, W) (mandatory) (1 byte) + +**PPPoE filtering:** (R, W) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### 9.3.8 MAC bridge port bridge table data + +This managed entity reports status data associated with a bridge port. The ONT automatically creates or deletes an instance of this managed entity upon the creation or deletion of a MAC bridge port configuration data. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a MAC bridge port configuration data managed entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +**Bridge table:** This attribute lists known MAC destination addresses, whether they are learned or statically assigned, whether packets having them as destination addresses are filtered or forwarded, and their ages. Each entry contains: + +- Information (2 bytes). +- MAC address (6 bytes). + +The information bits are assigned as described below. + +| Bit | Name | Setting | +|-------------------|--------------------|------------------------------------------------------------------------------| +| 1 (LSB) | Filter/forward | 0: forward
1: filter | +| 2 | Reserved | 0 | +| 3 | Dynamic/static | 0: this entry is statically assigned
1: this entry is dynamically learned | +| 4 | Reserved | 0 | +| 16..5 | Age | Age in seconds (1..4095) | + +Upon ME instantiation, this attribute is an empty list. (R) (mandatory) (8M bytes, where M is the number of entries in the list) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### **9.3.9 MAC bridge port performance monitoring history data** + +This managed entity collects performance monitoring data associated with a MAC bridge port. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a MAC bridge port configuration data managed entity. + +#### *Attributes* + +| | | +|----------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data ME. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Forwarded frame counter: | This attribute counts frames transmitted successfully on this port. (R) (mandatory) (4 bytes) | +| Delay exceeded discard counter: | This attribute counts frames discarded on this port because transmission was delayed. (R) (mandatory) (4 bytes) | +| MTU exceeded discard counter: | This attribute counts frames discarded on this port because the MTU was exceeded. (R) (mandatory) (4 bytes) | + +**Received frame counter:** This attribute counts frames received on this port. (R) (mandatory) (4 bytes) + +**Received and discarded counter:** This attribute counts frames received on this port that were discarded due to errors. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +**Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Reserved | | +| 1 | Delay exceeded discard | 1 | +| 2 | MTU exceeded discard | 2 | +| 3 | Reserved | | +| 4 | Received and discarded | 3 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.3.10 802.1p mapper service profile** + +This managed entity associates the priorities of 802.1P priority tagged frames with specific connections. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +At its root, an instance of this ME may be associated with zero or one instance of a PPTP UNI, MAC bridge port configuration data, or any type of interworking termination point ME that carries IEEE 802 traffic. Each of its eight branches is associated with zero or one GEM interworking termination point. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**TP pointer:** This attribute points to an instance of the associated termination point. The termination point type is determined by the TP type attribute: + +| TP type | TP pointer points to... | +|----------------|-------------------------------------------------------------------------------------------------| +| 0 | Bridging mapping. Pointer should be set to 0xFFFF by OLT and ignored by ONT. | +| 1 | PPTP Ethernet UNI. | +| 2 | IP host config data. | +| 3 | Ethernet flow TP. | +| 4 | PPTP xDSL UNI. | +| 5 | PPTP 802.11 UNI. | +| 6 | PPTP MoCA UNI. | +| Not supported | Bridging mapping if TP pointer value is 0xFFFF. TP pointer may also point to PPTP Ethernet UNI. | + +NOTE 1 – When the TP type is xDSL, the two most significant bits may be used to indicate a bearer channel. + +(R, W, Set-by-create) (mandatory) (2 bytes) + +Each of the following eight attributes points to the GEM interworking termination point associated with the stated P-bit value. The null pointer 0xFFFF specifies that frames with the associated priority are to be discarded. + +**Interwork TP pointer for P-bit priority 0:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 1:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 2:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 3:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 4:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 5:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 6:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 7:** (R, W, Set-by-create) (mandatory) (2 bytes) + +**Unmarked frame option:** This attribute specifies how the ONT should handle untagged Ethernet frames received across the associated interface. Valid values include: + +- 0 Convert from DSCP to 802.1p. +- 1 Tag frame to a certain value. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**DSCP to P-bit mapping:** This attribute is valid when the unmarked frame option attribute is set to 0. The DSCP to P-bit attribute can be considered a bit string sequence of 64 three-bit groupings. The 64 sequence entries represent the possible values of the six-bit DSCP field. Each three-bit grouping specifies the P-bit value to which the associated DSCP value should be mapped. Once marked, the P-bit marked frame is then directed to the GEM interworking termination point indicated by the interwork TP pointer mappings. (R, W) (mandatory) (24 bytes) + +NOTE 2 – If certain bits in the DSCP field are to be ignored in the mapping process, the attribute should be provisioned such that all possible values of those bits produce the same P-bit mapping. This can be applied to the case where the operator wishes to adopt the priority mechanism based on IP precedence instead of full DSCP, which needs only the three MSBs of the DSCP field. + +**Default P-bit marking:** This attribute is valid when the unmarked frame option attribute is set to 1. The default P-bit marking attribute contains the default P-bit priority setting to be applied. The P-bit marked frame is then directed to the GEM interworking termination point indicated by the interwork TP pointer mappings. (R, W, Set-by-create) (mandatory) (1 byte) + +**TP type:** This attribute identifies the type of termination point associated with the mapper. + +- 0 Mapper used for bridging-mapping. +- 1 Mapper directly associated with a PPTP Ethernet UNI. +- 2 Mapper directly associated with an IP host service. +- 3 Mapper directly associated with an Ethernet flow termination point. +- 4 Mapper directly associated with a PPTP xDSL UNI. +- 5 Mapper directly associated with a PPTP 802.11 UNI. +- 6 Mapper directly associated with a PPTP MoCA UNI. + +(R, W, Set-by-create) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.11 VLAN tagging filter data** + +This managed entity organizes data associated with VLAN tagging. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a MAC bridge port configuration data managed entity. By definition, tag filtering occurs closer to the MAC bridge than the tagging operation. Schematically, the ordering of the functions is: + +ANI – Tag\_operation – Tag\_filtering – Bridging – Tag\_filtering – Tag\_operation – UNI + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data ME. (R, Set-by-create) (mandatory) (2 bytes) + +**VLAN filter list:** This attribute lists provisioned TCI values for the bridge port. A TCI value (consisting of user priority, CFI and VID) is represented by 2 bytes. 12 VLAN entries are supported. The first N are valid, where N is given by the number of entries attribute. (R, W, Set-by-create) (mandatory) (24 bytes) + +**Forward operation:** When a frame is received, it is processed according to the operation specified by the forward operation table. (R, W, Set-by-create) (mandatory) (1 byte) + +| Forward operation | Type of received frame | | +|-------------------|------------------------------------------|------------| +| | Tagged | Untagged | +| 0x00 | Action (a) | Action (a) | +| 0x01 | Action (c) | Action (a) | +| 0x02 | Action (a) | Action (e) | +| 0x03 | Action (f) (VID investigation) | Action (a) | +| 0x04 | Action (f) (VID investigation) | Action (e) | +| 0x05 | Action (g) (VID investigation) | Action (a) | +| 0x06 | Action (g) (VID investigation) | Action (e) | +| 0x07 | Action (f) (user priority investigation) | Action (a) | +| 0x08 | Action (f) (user priority investigation) | Action (e) | +| 0x09 | Action (g) (user priority investigation) | Action (a) | +| 0x0A | Action (g) (user priority investigation) | Action (e) | +| 0x0B | Action (f) (TCI investigation) | Action (a) | +| 0x0C | Action (f) (TCI investigation) | Action (e) | +| 0x0D | Action (g) (TCI investigation) | Action (a) | +| 0x0E | Action (g) (TCI investigation) | Action (e) | +| 0x0F | Action (h) (VID investigation) | Action (a) | +| 0x10 | Action (h) (VID investigation) | Action (e) | +| 0x11 | Action (h) (user priority investigation) | Action (a) | +| 0x12 | Action (h) (user priority investigation) | Action (e) | +| 0x13 | Action (h) (TCI investigation) | Action (a) | +| 0x14 | Action (h) (TCI investigation) | Action (e) | +| 0x15 | Action (b) (Unconditional forwarding) | Action (e) | + +This table and the actions are discussed in detail below. + +**Number of entries:** This attribute specifies the number of valid entries in the VLAN filter list. (R, W, Set-by-create) (mandatory) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +#### **Supplementary explanation** + +This clause explains the actions specified in the forward operation attribute. + +The format of an Ethernet frame for VLAN services is described in [IEEE 802.1Q]: + +![Diagram showing the format of an Ethernet frame for VLAN services. The main frame structure consists of DA, SA, Length/type, and MAC SDU fields. A detailed view of the Length/type field shows it is replaced by TPID and TCI (Tag control information). The TCI field is further broken down into User priority (802.1P, 3 bits), CFI (1 bit), and VID (802.1Q) - VLAN ID (tag) (12 bits).](0f007a07756791edf7be50672cb010a4_img.jpg) + +| | | | | +|----|----|-----------------|---------| +| DA | SA | Length/
type | MAC SDU | +|----|----|-----------------|---------| + + + +| | | +|------|-------------------------------------| +| TPID | TCI
TCI: Tag control information | +|------|-------------------------------------| + + + +| | | | +|--------------------|----------------|-------------------------------------------| +| 802.1P
(3 bits) | CFI
(1 bit) | VID (802.1Q) - VLAN ID (tag)
(12 bits) | +|--------------------|----------------|-------------------------------------------| + +Diagram showing the format of an Ethernet frame for VLAN services. The main frame structure consists of DA, SA, Length/type, and MAC SDU fields. A detailed view of the Length/type field shows it is replaced by TPID and TCI (Tag control information). The TCI field is further broken down into User priority (802.1P, 3 bits), CFI (1 bit), and VID (802.1Q) - VLAN ID (tag) (12 bits). + +**Figure 9.3.11-1 – Format of an Ethernet frame for VLAN services** + +##### **a) Basic MAC bridge operation:** + +As shown in Figure 9.3.11-2, if the DA (destination MAC address) in the received frame is listed in the MAC bridge port bridge table data for one or more ports, this frame is forwarded on those ports. Otherwise, it is flooded to all ports except the receiving port. From the viewpoint of the transmitting port, a frame is forwarded either if its DA is in the port's MAC bridge port bridge table data or if its DA does not appear in the MAC bridge port bridge table data of any port on the bridge. This is the basic behaviour of a bridge that is not aware of VLANs. + +![Diagram illustrating basic MAC bridge operation. A MAC bridge port is shown with its bridge table data. Two received frames are shown: one with DA = a and another with DA = b. The frame with DA = a is forwarded to the port associated with 'a' in the bridge table. The frame with DA = b is flooded to all ports because there is no entry for 'b' in the bridge table. A note indicates that action (a) is cross-dependent on all ports.](142c0ec898fdb4803450dd39592136c5_img.jpg) + +Diagram illustrating basic MAC bridge operation. A MAC bridge port is shown with its bridge table data. Two received frames are shown: one with DA = a and another with DA = b. The frame with DA = a is forwarded to the port associated with 'a' in the bridge table. The frame with DA = b is flooded to all ports because there is no entry for 'b' in the bridge table. A note indicates that action (a) is cross-dependent on all ports. + +**Figure 9.3.11-2 – Basic MAC bridge operation** + +Other possible actions are as follows. + +- b) **Unconditional forwarding of tagged frame:** A tagged frame is forwarded without investigation of TCI. +- c) **Unconditional discarding of tagged frame:** A tagged frame is discarded without investigation of TCI. +- d) **Unconditional forwarding of untagged frame:** An untagged frame is forwarded without investigation of TCI. +- e) **Unconditional discarding of untagged frame:** An untagged frame is discarded without investigation of TCI. +- f) **Positive filtering by TCI:** If some or all (Note) of the fields in the TCI of the received frame are included in the VLAN filter list, it is forwarded according to action a) as shown in Figure 9.3.11-3. Otherwise, its TCI is ignored and it is controlled by action a). + +![Diagram illustrating positive filtering by TCI operation. A MAC bridge port uses bridge table data and VLAN tagging filter data to filter received tagged frames. The diagram shows three ports. The top port's filter data contains 'x', which matches the TCI of the first received frame (DA=a, TCI=x), allowing it to be forwarded. The middle port's filter data contains 'z', which does not match the TCI of the second received frame (DA=b, TCI=y), so it is not forwarded. The bottom port's filter data contains 'z', which matches the TCI of the third received frame (DA=b, TCI=z), allowing it to be forwarded. Arrows indicate the flow from received frames through the filter data to the bridge table data and then out of the ports. A label 'Operation based on action (a)' points to the bottom port's filter data entry.](d3162014eae89d17bf0117dabb0c8796_img.jpg) + +Diagram illustrating positive filtering by TCI operation. A MAC bridge port uses bridge table data and VLAN tagging filter data to filter received tagged frames. The diagram shows three ports. The top port's filter data contains 'x', which matches the TCI of the first received frame (DA=a, TCI=x), allowing it to be forwarded. The middle port's filter data contains 'z', which does not match the TCI of the second received frame (DA=b, TCI=y), so it is not forwarded. The bottom port's filter data contains 'z', which matches the TCI of the third received frame (DA=b, TCI=z), allowing it to be forwarded. Arrows indicate the flow from received frames through the filter data to the bridge table data and then out of the ports. A label 'Operation based on action (a)' points to the bottom port's filter data entry. + +**Figure 9.3.11-3 – Positive filtering by TCI operation** + +NOTE – The phrase *some or all* refers to the parts or the entirety of the TCI field called out by the specific value provisioned into the forward operation attribute. + +- g) **Negative filtering by TCI:** If some or all of the fields in the TCI of the received frame are included in the VLAN filter list, it is not forwarded by this port. Otherwise, it is forwarded according to action a) as shown in Figure 9.3.11-4. + +![Diagram of negative filtering by TCI operation. It shows a bridge with four ports. The top port is connected to a 'MAC bridge port bridge table data' block. The second port is connected to a 'VLAN tagging filter data' block containing 'x'. The third and fourth ports are connected to 'VLAN tagging filter data' blocks containing 'z'. On the right, three 'Received frames, tagged' are shown: 1) DA = a, TCI = x; 2) DA = b, TCI = y; 3) DA = b, TCI = z. Arrows indicate that the first frame (DA=a, TCI=x) is forwarded from the top port, the second frame (DA=b, TCI=y) is discarded, and the third frame (DA=b, TCI=z) is forwarded from the third port. A label 'Operation based on action (a)' points to the bridge.](f2a6c46fa05d5588ce4c6e1a3ee194c7_img.jpg) + +Diagram of negative filtering by TCI operation. It shows a bridge with four ports. The top port is connected to a 'MAC bridge port bridge table data' block. The second port is connected to a 'VLAN tagging filter data' block containing 'x'. The third and fourth ports are connected to 'VLAN tagging filter data' blocks containing 'z'. On the right, three 'Received frames, tagged' are shown: 1) DA = a, TCI = x; 2) DA = b, TCI = y; 3) DA = b, TCI = z. Arrows indicate that the first frame (DA=a, TCI=x) is forwarded from the top port, the second frame (DA=b, TCI=y) is discarded, and the third frame (DA=b, TCI=z) is forwarded from the third port. A label 'Operation based on action (a)' points to the bridge. + +**Figure 9.3.11-4 – Negative filtering by TCI operation** + +- h) **Positive filtering by TCI and dropping for no match:** If some or all of the fields in the TCI of the received frame are included in the VLAN filter list, it is forwarded according to action a) as shown in Figure 9.3.11-5. If its TCI is not accepted by any port on the bridge, the frame is discarded. + +![Diagram of positive filtering by TCI operation, dropping for no match. It shows a bridge with four ports. The top port is connected to a 'MAC bridge port bridge table data' block. The second port is connected to a 'VLAN tagging filter data' block containing 'b'. The third and fourth ports are connected to 'VLAN tagging filter data' blocks containing 'z'. On the right, three 'Received frames, tagged' are shown: 1) DA = a, TCI = x; 2) DA = b, TCI = y; 3) DA = b, TCI = z. Arrows indicate that the first frame (DA=a, TCI=x) is discarded because there is no TCI match, the second frame (DA=b, TCI=y) is forwarded from the second port, and the third frame (DA=b, TCI=z) is forwarded from the third port. A label 'Operation based on action (a)' points to the bridge.](6e9d059430baba0c363e33749f68b107_img.jpg) + +Diagram of positive filtering by TCI operation, dropping for no match. It shows a bridge with four ports. The top port is connected to a 'MAC bridge port bridge table data' block. The second port is connected to a 'VLAN tagging filter data' block containing 'b'. The third and fourth ports are connected to 'VLAN tagging filter data' blocks containing 'z'. On the right, three 'Received frames, tagged' are shown: 1) DA = a, TCI = x; 2) DA = b, TCI = y; 3) DA = b, TCI = z. Arrows indicate that the first frame (DA=a, TCI=x) is discarded because there is no TCI match, the second frame (DA=b, TCI=y) is forwarded from the second port, and the third frame (DA=b, TCI=z) is forwarded from the third port. A label 'Operation based on action (a)' points to the bridge. + +**Figure 9.3.11-5 – Positive filtering by TCI operation, dropping for no match** + +### 9.3.12 VLAN tagging operation configuration data + +This managed entity organizes data associated with VLAN tagging. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +Zero or one instance of this managed entity may exist for an instance of any managed entity that can terminate or modify an Ethernet stream. By definition, tagging operation occurs farther away from the MAC bridge than filtering. + +#### Attributes + +| | | +|------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. When the optional association type attribute is 0 or undefined, this attribute's value is the same as the id of the managed entity with which this VLAN tagging operation configuration data instance is associated, which may be either a PPTP Ethernet UNI or an IP host config data ME. Otherwise, the value of the ME ID is unconstrained except by the need to be unique. (R, Set-by-create) (mandatory) (2 bytes) | +| Upstream VLAN tagging operation mode: | This attribute controls upstream VLAN tagging. Valid values are:
0 Upstream frame is sent as is, regardless of tag.
1 The upstream frame is tagged, whether or not the received frame was tagged. The frame's TCI, consisting of VID, CFI and user priority, is attached or overwritten with the upstream VLAN tag TCI value.
2 The upstream frame is prepended with a tag, whether or not the received frame was tagged. If the received frame is tagged, a second tag (Q-in-Q) is added to the frame. If the received frame is not tagged, a tag is attached to the frame. The added tag is defined by the upstream VLAN tag TCI value attribute.
(R, W, Set-by-create) (mandatory) (1 byte) | +| Upstream VLAN tag TCI value: | This attribute specifies the TCI for upstream VLAN tagging. It is used when the upstream VLAN tagging operation mode is 1 or 2. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Downstream VLAN tagging operation mode: | This attribute controls downstream VLAN tagging. Valid values are:
0 Downstream frame is sent as is, regardless of tag.
1 If the received frame is tagged, the outer tag is stripped. An untagged frame is forwarded unchanged.
(R, W, Set-by-create) (mandatory) (1 byte) | +| Association type: | This attribute specifies the type of the ME that is associated with this VLAN tagging operation configuration data ME. Values are assigned in accordance with the following list:
0 (Default) Physical path termination point Ethernet UNI (for backward compatibility, may also be an IP host config data ME; they must not have the same ME ID). The associated ME instance is implicit; its identifier is the same as that of this VLAN tagging operation configuration data.
1 IP host config data.
2 802.1p mapper service profile.
3 MAC bridge port configuration data.
4 Physical path termination point xDSL UNI.
5 GEM interworking termination point.
6 Multicast GEM interworking termination point.
7 Physical path termination point MoCA UNI.
8 Physical path termination point 802.11 UNI.
9 Ethernet flow termination point.
10 Physical path termination point Ethernet UNI.
The associated ME instance is identified by the associated ME pointer. (R, W, Set-by-create) (optional) (1 byte) | + +**Associated ME pointer:** When the association type attribute is non-zero, this attribute points to the ME with which this VLAN tagging operation configuration data ME is associated. Otherwise, this attribute is undefined, and the association is implicit. + +NOTE – When the association type is xDSL, the two most significant bits may be used to indicate a bearer channel. + +(R, W, Set-by-create) (optional) (2 bytes) + +#### *Actions* + +#### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.13 Extended VLAN tagging operation configuration data** + +This managed entity organizes data associated with VLAN tagging. Regardless of its point of attachment, the specified tagging operations refer to the upstream direction. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +Zero or one instance(s) of this managed entity may exist for an instance of any managed entity that can terminate or modify an Ethernet stream. By definition, tagging operation occurs farther away from the MAC bridge than filtering. + +#### *Attributes* + +**Managed entity id:** This attribute provides a unique number for each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Association type:** This attribute identifies the type of the ME associated with this extended VLAN tagging ME. Values are assigned as follows: + +- 0 MAC bridge port configuration data. +- 1 802.1p mapper service profile. +- 2 Physical path termination point Ethernet UNI. +- 3 IP host config data. +- 4 Physical path termination point xDSL UNI. +- 5 GEM interworking termination point. +- 6 Multicast GEM interworking termination point. +- 7 Physical path termination point MoCA UNI. +- 8 Physical path termination point 802.11 UNI. +- 9 Ethernet flow termination point. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**Received frame VLAN tagging operation table max size:** This attribute indicates the maximum number of VLAN tagging operation entries that can be set in the received frame VLAN tagging operation table. (R) (mandatory) (2 bytes) + +**Input TPID:** This attribute gives the special TPID value for operations on the input (filtering) side of the table. Typical values include 0x88a8 and 0x9100. (R, W) (mandatory) (2 bytes) + +**Output TPID:** This attribute gives the special TPID value for operations on the output (tagging) side of the table. Typical values include 0x88a8 and 0x9100. (R, W) (mandatory) (2 bytes) + +**Downstream mode:** Regardless of its association, the extended VLAN tagging operation configuration data ME pertains to upstream traffic. This attribute specifies the mode for downstream mapping: + +- 0 The operation performed in the downstream direction is the inverse of that performed in the upstream direction. For one-to-one VLAN mappings, the inverse is trivially defined. Many-to-one mappings are possible, however, and these are treated as follows. If the many-to-one mapping results from multiple operation rules producing the same ANI-side tag configuration, then the first rule in the list defines the inverse operation. If the many-to-one mapping results from "do not care" fields in the filter being replaced with provisioned fields in the ANI-side tags, then the inverse is defined to set the corresponding fields on the ANI-side with their lowest value. +- 1 No operation is performed in the downstream direction. + +All other values are reserved. (R, W) (mandatory) (1 byte) + +**Received frame VLAN tagging operation table:** This attribute is a table that filters and tags upstream frames. Each entry represents a tagging rule, comprising a filtering part (the first 7 fields) and a treatment part (the last 7 fields). Each incoming upstream packet is matched against each rule in list order. The first rule that matches the packet is selected as the active rule, and the packet is then treated according to that rule. + +There are three categories of rules: zero-tag, single-tag, and double-tag rules. Logically, these categories are separate, and apply to their respective incoming frame types. In other words, a single-tag rule should not apply to a double-tagged frame, even though the single-tag rule might match the outer tag of the double-tagged frame. + +Single-tag rules have a filter outer priority field = 15 (indicating no external tag), zero-tag rules have both filter priority fields = 15 (indicating no tags), and double-tag rules have both filter priority fields set to a value that is different from 15 (indicating two tags). + +Each tagging rule is based on 'remove' and 'add' operation, where up to two tags can be removed or added. A modify operation is applied by the combination of 'remove' and 'add'. + +Note that when a single tag is added, the treatments use the 'inner tag' data-fields for definiteness – this is true even for treatments where a single tag is added to a frame that already has a tag, i.e., added as a second tag. The 'outer tag' data-fields are used only when two tags are added by the same rule. + +The terms 'inner' and 'outer' only have meaning with respect to the tags that are being filtered or added. + +One set operation can add, modify or delete one entry. The first 8 bytes of each entry are guaranteed to be unique, and are used to identify table entries (*list order*, above, refers to a sort on the first 8 bytes). The OLT deletes a table entry by setting its last eight bytes to all 0xFF. + +When the table is created, the ONT should predefine three entries that list the default treatment (of normal forwarding) for untagged, single-tagged, and double-tagged frames. As an exception to the rule on ordered processing, these default rules are always considered as a last resort for frames that do not match any other applicable rule. Best practice dictates that these entries not be deleted; however, they can be modified to produce the desired default behaviour. + +15, x, x, 15, x, x, x, (0, 15, x, x, 15, x, x) + +15, x, x, 14, x, x, x, (0, 15, x, x, 15, x, x) + +14, x, x, 14, x, x, x, (0, 15, x, x, 15, x, x) + +NOTE 1 – x is a "do not care" field and should be set to zero. + +(R, W) (mandatory) (16N bytes, where N is the number of VLAN tagging rules) + +![Received frame layout diagram showing four words (Word 1 to Word 4) with bit positions 32 to 1. Word 1 contains Filter outer priority, Filter outer VID, Filter outer TPID/DE, and Pad (reserved) 12 bits. Word 2 contains Filter inner priority, Filter inner VID, Filter inner TPID/DE, Pad (reserved) 8 bits, and Filter Ethertype. Word 3 contains Treatment, tags to remove, Pad (reserved) 10 bits, Treatment outer priority, Treatment outer VID, and Treatment outer TPID/DE. Word 4 contains Pad (reserved) 12 bits, Treatment inner priority, Treatment inner VID, and Treatment inner TPID/DE.](ff06304def736f4144f7bdd2957b9e22_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|--------|---------------------------|----|----|----|------------------------|----|----|----|------------------|----|----|----|--------------------------|----|----|----|----------------------|----|----|----|------------------------|----|----|---|-------------------------|---|---|---|------------------|---|---|---| +| | 32 | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| Word 1 | Filter outer priority | | | | | | | | Filter outer VID | | | | | | | | Filter outer TPID/DE | | | | Pad (reserved) 12 bits | | | | | | | | | | | | +| Word 2 | Filter inner priority | | | | | | | | Filter inner VID | | | | | | | | Filter inner TPID/DE | | | | Pad (reserved) 8 bits | | | | | | | | Filter Ethertype | | | | +| Word 3 | Treatment, tags to remove | | | | Pad (reserved) 10 bits | | | | | | | | Treatment outer priority | | | | Treatment outer VID | | | | | | | | Treatment outer TPID/DE | | | | | | | | +| Word 4 | Pad (reserved) 12 bits | | | | | | | | | | | | Treatment inner priority | | | | Treatment inner VID | | | | | | | | Treatment inner TPID/DE | | | | | | | | + +Received frame layout diagram showing four words (Word 1 to Word 4) with bit positions 32 to 1. Word 1 contains Filter outer priority, Filter outer VID, Filter outer TPID/DE, and Pad (reserved) 12 bits. Word 2 contains Filter inner priority, Filter inner VID, Filter inner TPID/DE, Pad (reserved) 8 bits, and Filter Ethertype. Word 3 contains Treatment, tags to remove, Pad (reserved) 10 bits, Treatment outer priority, Treatment outer VID, and Treatment outer TPID/DE. Word 4 contains Pad (reserved) 12 bits, Treatment inner priority, Treatment inner VID, and Treatment inner TPID/DE. + +Figure 9.3.13-1 – Received frame layout + +##### Received frame VLAN tagging operation table fields and operations + +**Filter outer priority:** (4 bits) + +- 0..7 Filter received frames on this outer priority (P-bit) value. + - 8 Do not filter on outer priority. + - 14 This is the default filter when no other two-tag rule applies. + - 15 This entry is not a double-tag rule; ignore all other outer tag filter fields. +- Other values: Reserved + +**Filter outer VID:** (13 bits) + +0..4094 Filter received frames on this outer VID value. + +4096 Do not filter on the outer VID. + +Other values: Reserved + +**Filter outer TPID/DE:** (3 bits) + +000 Do not filter on outer TPID field. + +100 Outer TPID = 8100. + +101 Outer TPID = input TPID attribute value, do not care about DE bit. + +110 Outer TPID = input TPID, DE=0. + +111 Outer TPID = input TPID, DE=1. + +Padding: 12 bits + +**Filter inner priority:** (4 bits) + +0..7 Filter received frames on this inner priority value. + +8 Do not filter on inner priority. + +14 This is the default filter when no other one-tag rule applies. + +15 This entry is a no-tag rule; ignore all other filter fields. + +Other values: Reserved + +**Filter inner VID:** (13 bits) + +0..4094 Filter received frames on this inner VID value. + +4096 Do not filter on the inner VID. + +Other values: Reserved + +**Filter inner TPID/DE:** (3 bits) + +000 Do not filter on inner TPID field. + +100 Inner TPID = 8100. + +101 Inner TPID = input TPID attribute value, don't care about DE bit. + +110 Inner TPID = input TPID, DE=0. + +111 Inner TPID = input TPID, DE=1. + +Padding: 8 bits + +**Filter Ethertype:** (4 bits) The Ethertype value on which to filter received frames, as listed below. + +NOTE 2 – This filter is recommended for use on untagged frames or frames with only priority. + +0 Do not filter on Ethertype. + +1 Ethertype = 0x0800 (filter IPoE frames). + +2 Ethertype = 0x8863 or 0x8864 (filter PPPoE frames). + +3 Ethertype = 0x0806 (filter ARP frames). + +Other values: Reserved + +**Treatment tags to remove:** (2 bits) + +0..2 Remove 0, 1 or 2 tags, respectively. If one tag is specified, then the outer tag is stripped from double-tagged frames. + +3 Reserved + +Padding: 10 bits + +##### **Treatment outer priority:** (4 bits) + +- 0..7 Add an outer tag, and insert this value as the priority in the outer VLAN tag. +- 8 Add an outer tag, and copy the outer priority from the inner priority of the received frame. +- 9 Add an outer tag, and copy the outer priority from the outer priority of the received frame. +- 15 Do not add an outer tag. + +Other values: Reserved + +##### **Treatment outer VID:** (13 bits) + +- 000..4094 Use this value as the VID in the outer VLAN tag. +- 4096 Copy the outer VID from the inner VID of the received frame. +- 4097 Copy the outer VID from the outer VID of the received frame. + +Other values: Reserved + +##### **Treatment outer TPID/DE:** (3 bits) + +- 000 Copy TPID (and DE, if present) from inner tag of received frame. +- 001 Copy TPID (and DE, if present) from outer tag of received frame. +- 010 Set TPID = output TPID attribute value, copy DE bit from inner tag of received frame. +- 011 Set TPID = output TPID, copy DE from outer tag of received frame. +- 100 Set TPID = 0x8100. +- 101 Reserved. +- 110 Set TPID = output TPID, DE=0. +- 111 Set TPID = output TPID, DE=1. + +Padding: 12 bits + +##### **Treatment inner priority:** (4 bits) + +- 0..7 Add an inner tag, and insert this value as the priority to insert in the inner VLAN tag. +- 8 Add an inner tag, and copy the inner priority from the inner priority of the received frame. +- 9 Add an inner tag, and copy the inner priority from the outer priority of the received frame. +- 15 Do not add an inner tag. + +Other values: Reserved + +**Treatment inner VID:** (13 bits) + +- 000..4094 Use this value as the VID in the inner VLAN tag. +- 4096 Copy the inner VID from the inner VID of the received frame. +- 4097 Copy the inner VID from the outer VID of the received frame. + +Other values: Reserved + +**Treatment inner TPID/DE:** (3 bits) + +- 000 Copy TPID (and DE, if present) from inner tag of received frame. +- 001 Copy TPID (and DE, if present) from outer tag of received frame. +- 010 Set TPID = output TPID attribute value, copy DE bit from inner tag of received frame. +- 011 Set TPID = output TPID, copy DE from outer tag of received frame. +- 100 Set TPID = 0x8100. +- 101 Reserved. +- 110 Set TPID = output TPID, DE=0. +- 111 Set TPID = output TPID, DE=1. + +**Associated ME pointer:** This attribute points to the ME with which this extended VLAN tagging operation configuration data ME is associated. + +NOTE 3 – When the association type is xDSL, the two most significant bits may be used to indicate a bearer channel. + +(R, W, Set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +**Create, delete, get, get next, set** + +#### *Notifications* + +None. + +| Action type | Filter | | | | | Treatment | | | | | +|---------------------------------------|----------|------|----------|------|-----------|----------------|----------|-----|----------|-----| +| | Outer | | Inner | | | Tags to Remove | Outer | | Inner | | +| | Priority | VID | Priority | VID | EtherType | | Priority | VID | Priority | VID | +| Untagged frames | | | | | | | | | | | +| Insert 1 full tag (X):
F → X-F | 15 | 4096 | 15 | 4096 | 0 | 0 | 15 | N/A | Px | X | +| Default case, do nothing | 15 | 4096 | 15 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | +| Insert 2 tags (X,Y):
F → Y-X-F | 15 | 4096 | 15 | 4096 | 0 | 0 | Py | Y | Px | X | +| Single tagged frames | | | | | | | | | | | +| Insert 1 full tag (X):
C-F → X-C-F | 15 | 4096 | 8 | C | 0 | 0 | 15 | N/A | Px | X | + +| Action type | Filter | | | | | Treatment | | | | | +|-----------------------------------------------------------------------------------|----------|------|----------|------|------------|----------------|----------|------|----------|------| +| | Outer | | Inner | | | Tags to Remove | Outer | | Inner | | +| | Priority | VID | Priority | VID | Ether-Type | | Priority | VID | Priority | VID | +| Insert 1 tag (X),
copy priority:
C-F → X-C-F | 15 | 4096 | 8 | C | 0 | 0 | 15 | N/A | 8 | X | +| Insert 2 tags (X,Y):
C-F → Y-X-C-F | 15 | 4096 | 8 | C | 0 | 0 | Py | Y | Px | X | +| Modify tag:
C-F → X-F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | Px | X | +| Modify tag,
keep original priority:
C-F → X-F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | 8 | X | +| Modify and insert tag:
C-F → Y-X-F | 15 | 4096 | 8 | C | 0 | 1 | Py | Y | Px | X | +| Remove tag:
C-F → F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | 15 | N/A | +| Default case, do nothing | 15 | 4096 | 14 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | +| Insert two tags:
C-F → Y-X-C-F | 15 | 4096 | 8 | C | 0 | 0 | Py | Y | Px | X | +| Double tagged frames | | | | | | | | | | | +| Insert 1 tag (X):
S-C-F → X-S-C-F | 8 | S | 8 | C | 0 | 0 | 15 | N/A | Px | X | +| Insert 1 tag (X),
copy external priority:
S-C-F → X-S-C-F | 8 | S | 8 | C | 0 | 0 | 15 | N/A | 9 | X | +| Insert 2 tags (X,Y):
S-C-F → Y-X-S-C-F | 8 | S | 8 | C | 0 | 0 | Py | Y | Px | X | +| Insert 2 tags (X,Y),
copy external and internal priority:
S-C-F → Y-X-S-C-F | 8 | S | 8 | C | 0 | 0 | 9 | Y | 8 | X | +| Modify external tag:
S-C-F → X-C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | Px | X | +| Modify external tag,
keep original priority:
S-C-F → X-C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | 9 | X | +| Modify both tags:
S-C-F → Y-X-F | 8 | S | 8 | C | 0 | 2 | Py | Y | Px | X | +| Modify both tags,
keep original priorities:
S-C-F → Y-X-F | 8 | S | 8 | C | 0 | 2 | 9 | Y | 8 | X | +| Swap both tags:
S-C-F → C-S-F | 8 | S | 8 | C | 0 | 2 | 8 | 4096 | 9 | 4097 | +| Remove outer tag:
S-C-F → C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | 15 | N/A | +| Remove both tags:
S-C-F → F | 8 | S | 8 | C | 0 | 2 | 15 | N/A | 15 | N/A | +| Default case, do nothing
S-C-F → S-C-F | 14 | 4096 | 14 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | + +### 9.3.14 Dot1X port extension package + +An instance of this managed entity represents a set of attributes that control a port's [b-IEEE 802.1X] operation. It is created and deleted autonomously by the ONT upon creation or deletion of a PPTP that supports 802.1X authentication. + +#### *Relationships* + +An instance of this managed entity is associated with a physical path termination point that performs IEEE 802 authentication (i.e., Ethernet or DSL). + +#### *Attributes* + +**Managed entity id:** This attribute provides a unique number for each instance of this managed entity. Its value is the same as that of its associated physical path termination point (i.e., slot and port number). + +NOTE – When the associated port is xDSL, the two most significant bits may be used to indicate a bearer channel. (R) (mandatory) (2 bytes) + +**Dot1x enable:** If set true, this Boolean attribute forces the associated port to authenticate via [b-IEEE 802.1X] as a precondition of normal service. The default value false does not impose 802.1X authentication on the associated port. (R, W) (mandatory) (1 byte) + +**Action register:** This attribute defines a set of actions that can be performed on the associated port. The act of writing to the register causes the specified action. + +- 1) Force reauthentication: This opcode initiates an 802.1X reauthentication conversation with the associated port. The port remains in its currently authorized state until the conversation concludes. + - 2) Force unauthenticated: This opcode initiates an 802.1X authentication conversation whose outcome is predestined to fail, thereby disabling normal Ethernet service on the port. The port's provisioning is not changed, such that upon reinitialization, a new 802.1X conversation may restore service without prejudice. + - 3) Force authenticated: This opcode initiates an 802.1X authentication conversation whose outcome is predestined to succeed, thereby unconditionally enabling normal Ethernet service on the port. The port's provisioning is not changed, such that upon reinitialization, a new 802.1X conversation is required. +- (W) (mandatory) (1 byte) + +**Authenticator PAE state:** This attribute returns the value of the port's PAE state. States are further described in [b-IEEE 802.1X]. Values are coded as shown below: + +- 0 Initialize. +- 1 Disconnected. +- 2 Connecting. +- 3 Authenticating. +- 4 Authenticated. +- 5 Aborting. +- 6 Held. +- 7 Force auth. +- 8 Force unauth. +- 9 Restart. + +(R) (optional) (1 byte) + +**Backend authentication state:** This attribute returns the value of the port's back-end authentication state. States are further described in [b-IEEE 802.1X]. Values are coded as shown below: + +- 0 Request. +- 1 Response. +- 2 Success. +- 3 Fail. +- 4 Timeout. +- 5 Idle. +- 6 Initialize. +- 7 Ignore. + +(R) (optional) (1 byte) + +**Admin controlled directions:** This attribute controls the directionality of the port's authentication requirement. The default value 0 indicates that control is imposed in both directions. The value 1 indicates that control is imposed only on traffic from the subscriber toward the network. (R, W) (optional) (1 byte) + +**Operational controlled directions:** This attribute indicates the actual directionality of the port's authentication. The value 0 indicates that control is imposed in both directions. The value 1 indicates that control is imposed only on traffic from the subscriber toward the network. (R) (optional) (1 byte) + +**Authenticator controlled port status:** This read-only attribute indicates whether the controlled port is currently authorized (1) or unauthorized (2). (R) (optional) (1 byte) + +**Quiet period:** This attribute specifies the interval between EAP request/identity invitations sent to the peer. Other events such as carrier present or EAPOL start frames from the peer may trigger an EAP request/identity frame from the ONT at any time; this attribute controls the ONT's periodic behaviour in the absence of these other inputs. It is expressed in seconds. (R, W) (optional) (2 bytes) + +- Server timeout period:** This attribute specifies the time the ONT will wait for a response from the radius server before timing out. Within this maximum interval, the ONT may initiate several retransmissions with exponentially increasing delay. Upon timeout, the ONT may try another radius server if there is one, or invoke the fallback policy, if no alternate radius servers are available. Server timeout is expressed in seconds, with a default value of 30 and a maximum value of 65535 seconds. (R, W) (optional) (2 bytes) +- Reauthentication period:** This attribute records the reauthentication interval specified by the radius authentication server. It is expressed in seconds. The attribute is only meaningful after a port has been authenticated. (R) (optional) (2 bytes) +- Reauthentication enabled:** This Boolean attribute records whether the radius authentication server has enabled reauthentication on this service (true) or not (false). The attribute is only meaningful after a port has been authenticated. (R) (optional) (1 byte) +- Key transmission enabled:** This Boolean attribute indicates whether key transmission is enabled (true) or not (false). This feature is not required; the parameter is listed here for completeness vis-à-vis [b-IEEE 802.1X]. (R, W) (optional) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +##### **Alarm** + +| Number | Alarm | Description | +|----------|--------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Dot1x local authentication – allowed | No radius authentication server was accessible. In accordance with local policy, the port was allowed access without authentication. | +| 1 | Dot1x local authentication – denied | No radius authentication server was accessible. In accordance with local policy, the port was denied access. | +| 2..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.3.15 Dot1X configuration profile** + +An instance of this managed entity represents a set of attributes that control an ONT's [b-IEEE 802.1X] operation with regard to IEEE 802 services. An instance of this managed entity is created by the ONT if it is capable of supporting [b-IEEE 802.1X]. + +#### *Relationships* + +One instance of this managed entity governs the ONT's 802.1X behaviour. + +#### *Attributes* + +| | | +|-----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute provides a unique number for each instance of this managed entity. There is at most one instance, number 0. (R) (mandatory) (2 bytes) | +| Circuit ID prefix: | This attribute is a pointer to a large string managed entity whose content appears as the prefix of the NAS port ID in radius access-request messages. The remainder of the NAS port ID field is local information (for example slot-port, appended by the ONT itself). The default value of this attribute is the null pointer 0. (R, W) (mandatory) (2 bytes) | +| Fallback policy: | When set to 1 (deny), this attribute causes 802.1X conversations to fail when no external authentication server is accessible, such that no Ethernet service is provided. The default value 0 causes 802.1X conversations to succeed when no external authentication server is accessible. (R, W) (mandatory) (1 byte) | +| Auth server 1: | This attribute is a pointer to a large string managed entity that contains the URI of the first choice radius authentication server. The value 0 indicates that no radius authentication server is specified. (R, W) (mandatory) (2 bytes) | +| Shared secret auth1: | This attribute is the shared secret for the first radius authentication server. It is a null-terminated character string. (R, W) (mandatory) (25 bytes) | +| | The following two pairs of attributes are defined in the same way: | +| Auth server 2: | (R, W) (optional) (2 bytes) | +| Shared secret auth2: | (R, W) (optional) (25 bytes) | +| Auth server 3: | (R, W) (optional) (2 bytes) | +| Shared secret auth3: | (R, W) (optional) (25 bytes) | +| OLT proxy address: | This attribute indicates the IP address of a possible proxy at the OLT for 802.1X radius messages. The default value 0.0.0.0 indicates that no proxy is required. (R, W) (optional) (4 bytes) | + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.3.16 Dot1X performance monitoring history data** + +This managed entity collects performance statistics on an ONT's IEEE 802.1X operation. Instances of this managed entity are created and deleted by the ONT on request of the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with each UNI that can perform IEEE 802 authentication. + +#### *Attributes* + +| | | +|---------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of a physical path termination point. (R, Set-by-create) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| EPOL frames received: | This attribute counts received valid EPOL frames of any type. (R) (mandatory) (4 bytes) | +| EPOL frames transmitted: | This attribute counts transmitted EPOL frames of any type. (R) (mandatory) (4 bytes) | +| EPOL start frames received: | This attribute counts received EPOL start frames. (R) (mandatory) (4 bytes) | +| EPOL logoff frames received: | This attribute counts received EPOL logoff frames. (R) (mandatory) (4 bytes) | +| Invalid EPOL frames received: | This attribute counts received EPOL frames in which the frame type was not recognized. (R) (mandatory) (4 bytes) | +| EAP resp/id frames received: | This attribute counts received EAP response frames containing an identifier type field. (R) (mandatory) (4 bytes) | +| EAP response frames received: | This attribute counts received EAP response frames, other than resp/id frames. (R) (mandatory) (4 bytes) | +| EAP initial request frames transmitted: | This attribute counts transmitted request frames containing an identifier type field. In [b-IEEE 802.1X], this is also called ReqId. (R) (mandatory) (4 bytes) | +| EAP request frames transmitted: | This attribute counts transmitted request frames, other than request/id frames. (R) (mandatory) (4 bytes) | +| EAP length error frames received: | This attribute counts received EPOL frames whose packet body length field was invalid. (R) (mandatory) (4 bytes) | +| EAP success frames generated autonomously: | This attribute counts EPOL success frames generated according to local fallback policy because no radius server was available. (R) (mandatory) (4 bytes) | +| EAP failure frames generated autonomously: | This attribute counts EPOL failure frames generated according to local fallback policy because no radius server was available. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|----------|----------------------------------|------------------------------------| +| 0..3 | Reserved | | +| 4 | Invalid EAPOL frames received | 5 | +| 5..8 | Reserved | | +| 9 | EAP length error frames received | 10 | +| 10..207 | Reserved | | +| 208..223 | Vendor-specific alarms | | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.3.17 Radius performance monitoring history data + +This managed entity collects performance statistics on an ONT's radius client, particularly as related to its 802.1X operation. + +Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity is associated with an ONT. + +#### Attributes + +| | | +|---------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID (namely 0), this managed entity is implicitly linked to an instance of a dot1X configuration profile. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Access-request packets transmitted: | This attribute counts transmitted radius access-request messages, including retransmissions. (R) (mandatory) (4 bytes) | +| Access-request retransmission count: | This attribute counts radius access-request retransmissions. (R) (mandatory) (4 bytes) | +| Access-challenge packets received: | This attribute counts received radius access-challenge messages. (R) (mandatory) (4 bytes) | +| Access-accept packets received: | This attribute counts received radius access-accept messages. (R) (mandatory) (4 bytes) | +| Access-reject packets received: | This attribute counts received radius access-reject messages. (R) (mandatory) (4 bytes) | +| Invalid radius packets received: | This attribute counts received invalid radius messages. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|---------------|---------------------------------|-------------------------------------------| +| 0 | Reserved | | +| 1 | Retransmission count | 2 | +| 2..4 | Reserved | | +| 5 | Invalid radius packets received | 6 | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.3.18 Dot1 rate limiter** + +This managed entity allows rate limits to be defined for various types of upstream traffic that are processed by 802.1 bridges or related structures. + +#### *Relationships* + +An instance of this managed entity may be linked to an instance of the MAC bridge service profile, an 802.1p mapper or other managed entities. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) +- Parent ME pointer:** This attribute points to an instance of a managed entity. The type of managed entity is determined by the TP type attribute. (R, W, Set-by-create) (mandatory) (2 bytes) +- TP type:** This attribute identifies the type of termination point associated with this dot1 rate limiter. Valid values are: +- 1 MAC bridge configuration data. + - 2 802.1p mapper service profile. +- (R, W, Set-by-create) (mandatory) (1 byte) +- Upstream unicast flood rate pointer:** This attribute points to an instance of the GEM traffic descriptor that specifies the maximum rate of upstream unicast packets whose destination address is unknown to the bridge. A null pointer specifies that no administrative limit is to be imposed. (R, W, Set-by-create) (optional) (2 bytes) +- Upstream broadcast rate pointer:** This attribute points to an instance of the GEM traffic descriptor that specifies the maximum rate of upstream broadcast packets. A null pointer specifies that no administrative limit is to be imposed. (R, W, Set-by-create) (optional) (2 bytes) + +**Upstream multicast payload rate pointer:** This attribute points to an instance of the GEM traffic descriptor that specifies the maximum rate of upstream multicast payload packets. A null pointer specifies that no administrative limit is to be imposed. (R, W, Set-by-create) (optional) (2 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.19 Dot1ag maintenance domain** + +A maintenance domain (MD) is a context within which CFM connectivity verification can occur. Individual services (maintenance associations: MAs) exist within an MD. A maintenance domain is created and deleted by the OLT. The MD managed entity is specified by [b-IEEE 802.1ag] in such a way that the same provisioning can be used for all associated systems in a network; the OMCI definition accordingly avoids ONT-specific information such as pointers. + +#### *Relationships* + +Several MDs may be associated with a given bridge, at various MD levels, and a given MD may be associated with any number of bridges. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies an instance of this managed entity. The values 0 and 0xFFFF are reserved. (R, Set-by-create) (mandatory) (2 bytes) + +**MD level:** This attribute ranges from 0..7 and specifies the maintenance level of this MD. Higher numbers have wider geographic scope. (R, W, Set-by-create) (mandatory) (1 byte) + +**MD name format:** This attribute specifies one of several possible formats for the MD name attribute. (R, W, Set-by-create) (mandatory) (1 byte) + +| Value | MD name format | MD name attribute | Defined in | +|--------|-------------------|------------------------------------------------------------------------------------------------|----------------------------| +| 1 | None | No MD name present | [b-IEEE 802.1ag] | +| 2 | DNS-like name | Globally unique text string derived from a DNS name | " | +| 3 | MAC addr and UINT | MAC address, followed by a two-octet unsigned integer, total length 8 bytes | " | +| 4 | Character string | String of printable characters. This is recommended to be the default value. | " | +| 32 | ICC-based | ITU carrier code followed by locally assigned UMC code, 13 bytes with trailing nulls as needed | [b-ITU-T Y.1731] (Annex A) | +| Others | Reserved | | | + +**MD name 1, MD name 2:** These two attributes may be regarded as a 50-byte octet string whose value is the left-justified maintenance domain name. The MD name may or may not be a printable character string, so an octet string is the appropriate representation. If the MD name format specifies a DNS-like name or a character string, the string is null-terminated; otherwise its length is determined by the MD name format. If the MD has no name (MD name format = 0), this attribute is undefined. Note that binary comparisons of the MD name are made in other CFM state machines, so blanks, alphabetic case, etc., are significant. Further note that the maintenance domain name and the maintenance association name must be packed (with additional bytes) into 48-byte CFM message headers. (R, W) (mandatory if MD name format is not 1) (25 bytes \* 2 attributes) + +**MHF creation:** This attribute determines whether an associated bridge creates an MHF for this MD or not, under circumstances defined in clause 22.2.3 of [b-IEEE 802.1ag]. This attribute is an enumeration with the following values: + +- 1 None, the default value. +- 2 Default. The bridge can create MHFs on an associated VID on any port through which the VID can pass, where: i) there are no lower active MD levels or ii) there is a MEP at the next lower active MD level on the port. +- 3 Explicit. The bridge can create MHFs on an associated VID on any port through which the VID can pass, but only if a MEP exists at some lower maintenance level. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**Sender ID permission:** This attribute determines the content of the sender ID TLV included in CFM messages transmitted by maintenance points controlled by this MD. Chassis ID and management address information is available from the dot1ag chassis-management info managed entity. The attribute is an enumeration with the following values: + +- 1 None: The sender ID TLV is not to be sent, default. +- 2 Chassis: The chassis ID length, chassis ID subtype, and chassis ID fields of the sender ID TLV are to be sent, but not the management address fields. +- 3 Manage: The management address fields of the sender ID TLV are to be sent, but the chassis ID length is to be transmitted with a 0 value, and the chassis ID subtype, and chassis ID fields are not to be sent. +- 4 ChassisManage: All chassis ID and management address fields are to be sent. + +(R, W, Set-by-create) (mandatory) (1 byte) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +### 9.3.20 Dot1ag maintenance association + +This managed entity models an IEEE 802.1 service defined on a bridge port. A maintenance association (MA) is a set of endpoints on opposite sides of a network, all existing at a defined maintenance level. One of the endpoints resides on the local ONT; the others are understood to be configured in a consistent way on external equipments. [b-ITU-T Y.1731] refers to the MA as a maintenance entity group (MEG). + +A maintenance association is created and deleted by the OLT. + +#### *Relationships* + +Any number of MAs may be associated with a given maintenance domain, or may stand on their own without an MD. One or more MAs may be associated with a MAC bridge or 802.1p mapper. An MA exists at one of eight possible maintenance levels. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies an instance of this managed entity. The values 0 and 0xffff are reserved. (R, Set-by-create) (mandatory) (2 bytes) + +**MD pointer:** This pointer specifies the dot1ag maintenance domain with which this MA is associated. The default null pointer specifies that the MA is not associated with an MD. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Short MA name format:** This attribute specifies one of several possible formats for the short MA name attribute. Value 1, the primary VLAN ID, is recommended to be the default. (R, W, Set-by-create) (mandatory) (1 byte) + +| Value | Short MA name format | Short MA name attribute | +|-------|----------------------|--------------------------------------------------| +| 1 | Primary VID | 2 octets, 12 LSBs specify primary VID, 0 if none | +| 2 | Character string | String of up to 45 printable characters | +| 3 | Two-byte integer | 2-octet unsigned integer | +| 4 | VPN ID | 7 octets, as defined in [b-IETF RFC 2685] | +| Other | Reserved | | + +**Short MA name 1, Short MA name 2:** These two attributes may be regarded as an octet string whose value is the left-justified maintenance association name. Because the MA name may or may not be a printable character string, an octet string is the appropriate representation. If the short MA name format specifies a character string, the string is null-terminated; otherwise its length is determined by the short MA name format. Note that binary comparisons of the short MA name are made in other CFM state machines, so blanks, alphabetic case, etc., are significant. Further note that the maintenance domain name and the maintenance association short name must be packed (with additional bytes) into 48-byte CFM message headers. (R, W) (mandatory) (25 bytes \* 2 attributes) + +**CCM interval:** If CCMs are enabled on a MEP, the CCM interval attribute specifies the rate at which they are generated. The MEP also expects to receive CCMs from each of the other MEPs in its CC database at this rate. + +- 0: CCM transmission disabled. +- 1: 3.33 ms. +- 2: 10 ms. +- 3: 100 ms. +- 4: 1 s. +- 5: 10 s. +- 6: 1 min. +- 7: 10 min. + +Short intervals should be used judiciously, as they can interfere with the network's ability to handle subscriber traffic. The recommended value is 1 second. (R, W, Set-by-create) (mandatory) (1 byte) + +**Associated VLANs:** This attribute is a list of up to 12 VLAN IDs with which this MA is associated. Once a set of VLANs is defined, the ONT should deny operations to other dot1ag maintenance associations or dot1ag default MD level entries that conflict with the set membership. The all-zeros value indicates that this MA is not associated with any VLANs. Assuming that the attribute is not 0, the first entry is understood to be the primary VLAN. Except forwarded LTMs, CFM messages emitted by maintenance points in this MA are tagged with the primary VLAN ID. (R, W) (mandatory) (2 bytes/entry \* 12 entries = 24 bytes) + +**MHF creation:** This attribute determines whether the bridge creates an MHF or not, under circumstances defined in clause 22.2.3 of [b-IEEE 802.1ag]. This attribute is an enumeration with the following values: + +- 1 None; no MHFs are created on this bridge for this MA. +- 2 Default. The bridge can create MHFs on this VID on any port through which the VID can pass. +- 3 Explicit. The bridge can create MHFs on this VID on any port through which the VID can pass, but only if a MEP exists at some lower maintenance level. +- 4 Defer. This value causes the ONT to use the setting of the parent MD. This is recommended to be the default value. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**Sender ID permission:** This attribute determines the content of the sender ID TLV included in CFM messages transmitted by maintenance points controlled by this MA. This attribute is the same as that defined in the description of the dot1ag maintenance domain managed entity, with the addition of code point 5. + +- 1 None: The sender ID TLV is not to be sent, default. +- 2 Chassis: The chassis ID length, chassis ID subtype, and chassis ID fields of the sender ID TLV are to be sent, but not the management address fields. + +- 3 Manage: The management address fields of the sender ID TLV are to be sent, but the chassis ID length is to be transmitted with a 0 value, and the chassis ID subtype, and chassis ID fields are not to be sent. +- 4 ChassisManage: All chassis ID and management address fields are to be sent. +- 5 Defer: The content of the sender ID TLV is determined by the corresponding maintenance domain attribute. This is recommended to be the default value. + +(R, W, Set-by-create) (mandatory) (1 byte) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.21 Dot1ag default MD level** + +An MHF is a collection of functionality that is not explicitly modelled as a managed entity by either [b-IEEE 802.1ag] or OMCI. The ONT automatically creates MHFs according to parameters specified in a dot1ag maintenance domain or a dot1ag maintenance association ME; the dot1ag default MD level ME catches the corner cases not covered by other MEs, specifically VLANs not included by any defined MA. + +The dot1ag default MD level comprises a configurable table, each entry of which specifies default MHF functionality for some set of VLANs. Once a set of VLANs is defined, operations to different table entries or to dot1ag maintenance associations that conflict with the set membership should be denied. In addition, catch-all attributes are defined to specify MHF functionality when there is no match to either a table entry or an MA. + +#### *Relationships* + +An ONT that supports [b-IEEE 802.1ag] automatically creates one instance of this ME for each MAC bridge or 802.1p mapper, depending on the ONT's provisioning model. It should not create an instance for an 802.1p mapper that is associated with a MAC bridge. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies an instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge service profile ME or an 802.1p mapper ME. It is expected that an ONT will implement CFM on bridges or on 802.1p mappers, but not both, depending on its provisioning model. For precision, the reference is disambiguated by the value of the layer 2 type pointer attribute. (R) (mandatory) (2 bytes) +- Layer 2 type:** This attribute specifies whether the dot1ag default MD level ME is associated with a MAC bridge service profile (value 0) or an 802.1p mapper (value 1). (R) (mandatory) (1 byte) +- Catchall level:** This attribute ranges from 0..7 and specifies the MD level of MHFs created when no more specific match is found. (R, W) (mandatory) (1 byte) + +| | | +|---------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Catchall MHF creation: | This attribute determines whether, when no more specific match is found, the bridge creates an MHF or not. This attribute is an enumeration with the following values:
1 None; the bridge creates no MHFs. This is the default value.
2 Default. The bridge can create MHFs on this VID on any port through which the VID can pass.
3 Explicit. The bridge can create MHFs on this VID on any port through which the VID can pass, but only if a MEP exists at some lower maintenance level.
(R, W) (mandatory) (1 byte) | +| Catchall sender ID permission: | This attribute determines the content of the sender ID TLV included in CFM messages transmitted by maintenance points when no more specific match is found. This attribute is identical to that defined in the description of the dot1ag maintenance domain managed entity (i.e., excluding codepoint 5, defer). (R, W) (mandatory) (1 byte) | +| Default MD level table: | Each entry is a vector of fields, indexed by primary VLAN ID. | +| Primary VLAN ID | (2 bytes) | +| Table control: | This field controls the meaning of a set operation. The one-byte size of this field is included in get/get-next operations, but its value is undefined under get-next. (1 byte)
1 Add record to table; overwrite existing record, if any.
2 Delete record from table.
3 Clear all entries from table. This action may affect service and should be used judiciously.
Other values reserved. | +| Status: | This Boolean field indicates whether this table entry is in effect (true) or whether (false) it has been overridden by the existence of an MA for the same VID and MD level as this table's entry, and on which an up MEP is defined. This attribute is read-only. Space should be allocated for it during set operations, but the value is not used. (1 byte) | +| Level: | This field ranges from 0..7 and specifies the MD level of MHFs under the control of this instance of the dot1ag default MD level. The additional value 0xFF instructs the bridge to use the value in the catchall level attribute. (1 byte) | +| MHF creation: | This attribute determines whether the bridge creates an MHF or not, under circumstances defined in clause 22.2.3 of [b-IEEE 802.1ag]. This attribute is an enumeration with the following values (1 byte):
1 None; no MHFs are created on this bridge for this MA.
2 Default. The bridge can create MHFs on this VID on any port through which the VID can pass.
3 Explicit. The bridge can create MHFs on this VID on any port through which the VID can pass, but only if a MEP exists at some lower maintenance level. | + +- 4 Defer. This value causes the ONT to use the setting of the catchall MHF creation attribute. This is recommended to be the default value. + +**Sender ID permission:** This attribute determines the content of the sender ID TLV included in CFM messages transmitted by maintenance points controlled by this MA. (1 byte) + +- 1 None: The sender ID TLV is not to be sent, default. +- 2 Chassis: The chassis ID length, chassis ID subtype, and chassis ID fields of the sender ID TLV are to be sent, but not the management address fields. +- 3 Manage: The management address fields of the sender ID TLV are to be sent, but the chassis ID length is to be transmitted with a 0 value, and the chassis ID subtype, and chassis ID fields are not to be sent. +- 4 ChassisManage: All chassis ID and management address fields are to be sent. +- 5 Defer: The content of the sender ID TLV is determined by the catchall sender ID permission attribute. + +**Associated VLANs list:** This field comprises a list of up to 11 additional VLAN IDs associated with the primary VLAN, 2 bytes each. Unused placeholders, possibly including the entire field, are set to 0. (22 bytes) + +(R, W) (mandatory) (29 bytes \* N entries) + +#### *Actions* + +#### **Get, get next, set** + +#### *Notifications* + +None. + +### **9.3.22 Dot1ag MEP** + +This managed entity models a maintenance association end point (MEP) as defined primarily in [b-IEEE 802.1ag] and secondarily in [b-ITU-T Y.1731]. It is created and deleted by the OLT. A MEP exists at one of eight possible maintenance levels, and resides at the boundary of a maintenance domain. It inherits a name, and optionally a set of associated VLANs, from its associated MA. + +#### *Relationships* + +One or more MEPs may be associated with a MAC bridge port or an 802.1p mapper in the absence of a MAC bridge. A MEP is also associated with zero or more VLANs and a maintenance association. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Layer 2 entity pointer:** Depending on the value of the layer 2 type attribute, this pointer specifies the MAC bridge port configuration data ME or the 802.1p mapper service profile ME with which this MEP is associated. (R, W, Set-by-create) (mandatory) (2 bytes) + +- Layer 2 type:** This attribute specifies whether the MA is associated with a MAC bridge port (value 0) or an 802.1p mapper (value 1). (R, W, Set-by-create) (mandatory) (1 byte) +- MA pointer:** This pointer specifies the maintenance association (MA) with which this MEP is associated. (R, W, Set-by-create) (mandatory) (2 bytes) +- MEP ID:** This attribute specifies the MEP's own identity in the MA. For a given MA, the MEP ID must be unique throughout the network defined by the MD. The MEP ID is defined in the range 1..8191. The default value 0 indicates that no MEP ID is (yet) configured. (R, W, Set-by-create) (mandatory) (2 bytes) +- MEP control:** This attribute specifies some of the overall behavioural aspects of the MEP. It is interpreted as follows. Ethernet AIS generation should not be enabled simultaneously with CCMs. + +| Bit | Interpretation when bit value = 1 | +|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Reserved | +| 2 | MEP generates continuity check messages, CCMs | +| 3 | Enable Y.1731 server MEP function | +| 4 | Enable generation of Ethernet AIS | +| 5 | This is an up MEP, facing toward the core of the bridge. If more than one MEP exists on a given maintenance association and on a given bridge, all such MEPs must face the same direction. | +| 6..8 | Reserved | + +(R, W, Set-by-create) (mandatory) (1 byte) + +- Primary VLAN:** This attribute is a 12-bit VLAN ID. The value 0 indicates that the MEP inherits its primary VLAN from its parent MA. CFM messages, except forwarded LTMs, are tagged with the primary VLAN ID. If explicitly specified, the value of this attribute must be one of the VLANs associated with the parent MA. (R, W, Set-by-create) (mandatory) (2 bytes) +- Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all functions are blocked, and alarms for this managed entity are no longer generated. Because spurious alarms may be generated during the process of configuring CFM across a network, the default value for this attribute is locked. (R, W, Set-by-create) (mandatory) (1 byte) +- CCM and LTM priority:** By default, CCM and LTM frames are transmitted with the highest Ethernet priority available. Ranging from 0..7, this attribute permits these frames to be explicitly prioritized, which may be needed if flows are separated, e.g., by 802.1p priority. The priority specified in this attribute is also used in LTR frames originated by this MEP. (R, W, Set-by-create) (mandatory) (1 byte) + +**Egress identifier:** This attribute comprises 8 bytes to be included in LTMs. They allow received LTRs to be directed to the correct originator. The attribute includes the originator MAC address and a locally-defined identifier. If this field is 0 (default), the ONT uses the MEP's MAC address, with 0 as the locally-defined identifier. (R, W, Set-by-create) (mandatory) (8 bytes) + +**Peer MEP IDs:** This attribute lists the expected peer MEPs for CCMs, 2 bytes per MEP ID. [b-IEEE 802.1ag] allows for multipoint networks, and therefore a list of peer MEPs. This attribute allows for up to 12 peers for a given MEP, though G-PON applications are expected to need only a single peer. Missing or unexpected messages trigger alarm declaration after a soak interval. Unused peer MEP slots should be set to 0. (R, W) (mandatory) (24 bytes) + +**ETH AIS control:** This attribute controls the generation of Ethernet AIS frames when they are enabled through the MEP control attribute. It is interpreted as follows: + +| Bit | Interpretation | +|---------|-----------------------------------------------------------------| +| 1 (LSB) | Transmission period
0: Once per second
1: Once per minute | +| 2..4 | P-bit priority of transmitted ETH AIS frames | +| 5..7 | The maintenance level at which the client MEP exists | +| 8 | Reserved | + +(R, W, Set-by-create) (mandatory if ETH AIS is enabled) (1 byte) + +**Fault alarm threshold:** This attribute specifies the lowest priority alarm that is allowed to generate a fault alarm. It is defined as follows: + +- 1 All defects generate alarms after suitable soaking, including AIS and RDICCM. +- 2 Alarm generated only by one of: MACstatus, RemoteCCM, ErrorCCM, XconCCM. This value is recommended as the default in [b-IEEE 802.1ag]. +- 3 Alarm generated only by one of: RemoteCCM, ErrorCCM, XconCCM. +- 4 Alarm generated only by one of: ErrorCCM, XconCCM. +- 5 Alarm generated only by: XconCCM. +- 6 No alarms are to be reported. This setting may be useful during configuration of services across the network when spurious alarms could otherwise be generated. + +(R, W, Set-by-create) (optional) (1 byte) + +**Alarm declaration soak time:** This attribute defines the defect soak time that must elapse before the MEP declares an alarm. It is expressed in ten-millisecond units with a range of 250 to 1000, i.e., 2.5 to 10 seconds. The default is recommended to be 2.5 seconds. (R, W) (mandatory) (2 bytes) + +**Alarm clear soak time:** This attribute defines the defect-free soak time that must elapse before the MEP clears an alarm. It is expressed in ten-millisecond units with a range of 250 to 1000, i.e., 2.5 to 10 seconds. The default is recommended to be 10 seconds. (R, W) (mandatory) (2 bytes) + +#### Actions + +##### Create, delete, get, set + +**Test:** The test operation causes the MEP to originate one or more loopback messages (LBMs) or a linktrace message (LTM) in accordance with the message format defined in clause II.2.27. + +The link trace test returns its results in a general purpose buffer ME, which must have been created in advance by the OLT. Upon completion of the linktrace operation, the general purpose buffer contains a sequence of LTR entries in the order they were received: + +| Length field, 2 bytes | Length bytes | +|-----------------------|-----------------------------------------------------------| +| Length of LTR1 | LTR: link trace reply 1 (clause 21.9 of [b-IEEE 802.1ag]) | +| Length of LTR2 | LTR: link trace reply 2 | +| Etc. | | + +[b-IEEE 802.1ag] defines the data structure for the linktrace database in detail, but the definition is essentially the same as the LTR PDU itself. OMCI simply records the messages for parsing and analysis at the OLT or the EMS. + +If the ONT cannot allocate enough memory for the entire list, it keeps the most recent responses and discards the older LTRs as necessary (LTR1, LTR2, ...). + +#### Notifications + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|-----------------------------------------------| +| 0 | RDI CCM | RDI received in CCM from peer MEP | +| 1 | MAC status | Port or interface status failure at peer MEP | +| 2 | Remote CCM | Loss of continuity with peer MEP | +| 3 | Error CCM | Invalid CCMs received | +| 4 | Xcon CCM | CCMs received from other MA or lower MD level | +| 5 | Unexpected period | Unexpected period | +| 6 | AIS | Ethernet AIS received | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.3.23 Dot1ag MEP status + +This managed entity is the read-only twin of the dot1ag MEP. Its purpose is to return information that may help in system- or network-level troubleshooting. It is automatically created and deleted by the ONT at the time its MEP is created or deleted. + +As the reporter of ephemeral information, the dot1ag MEP status ME is not persistent and is not included in MIB uploads. + +#### *Relationships* + +A dot1ag MEP status ME is associated with a dot1ag MEP ME. + +##### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the dot1ag MEP ME. (R) (mandatory) (2 bytes) + +**MEP MAC address:** This attribute records the MEP's MAC address. (R) (mandatory) (6 bytes) + +**Fault notification generator state:** This attribute records the current state of the MEP's fault notification generator state machine. States are defined in clause 20.35 of [b-IEEE 802.1ag]. + +- 1 Reset +- 2 Defect +- 3 Report defect +- 4 Defect reported +- 5 Defect clearing + +(R) (mandatory) (1 byte) + +**Highest priority defect observed:** This attribute records the highest priority defect observed since the fault notification state machine was last in reset state. In increasing priority order, possible values are: + +- 0 No defect observed. +- 1 Received a CCM from a remote MEP in which the RDI bit was set. +- 2 Received a CCM from a remote MEP in which the port status or interface status TLV reported an error. +- 3 No CCMs received for at least $3.5 \times \text{CCM interval}$ from at least one remote MEP in the MA. +- 4 Received invalid CCMs for at least $3.5 \times \text{CCM interval}$ . +- 5 Received CCMs for at least $3.5 \times \text{CCM interval}$ that could be from some other MA. + +(R) (mandatory) (1 byte) + +**Current defects:** This attribute is a bit field that signals several events of interest in real time. + +###### | Bit | Meaning when set | |---------|----------------------------------------------------------------------------------------------------------------------------------| | 1 (LSB) | Some other MEP in the same MA is currently transmitting RDI. | | 2 | A port status or interface status TLV received from some other MEP in the MA is currently indicating an error condition. | | 3 | CCMs have not been received for at least $3.5 \times \text{CCM interval}$ from at least one of the expected remote MEPs. | | 4 | Erroneous CCMs have been received for at least $3.5 \times \text{CCM interval}$ from at least one of the remote MEPs in this MA. | | 5 | CCMs have been received for at least $3.5 \times \text{CCM interval}$ from a MEP that is not configured into the current MA. | | 6..8 | Reserved | + +(R) (mandatory) (1 byte) + +**Last received errored CCM:** This attribute contains the most recently received CCM that contributed to a defErrorCCM fault. If no such CCM has been received, this attribute is null. The format of the CCM is defined in clause 21.6 of [b-IEEE 802.1ag]. (R) (mandatory) (N bytes, not to exceed 128) + +**Last received xcon CCM:** This attribute contains the most recently received CCM that contributed to a defXconCCM fault. If no such CCM has been received, this attribute is null. (R) (mandatory) (N bytes, not to exceed 128) + +**Out of sequence CCMs count:** This attribute records the number of out of sequence CCMs received. When the counter is full, it rolls over to 0. (R) (optional) (4 bytes) + +**CCMs transmitted count:** This attribute records the number of CCMs transmitted. It may be used as the sequence number of transmitted CCMs. When the counter is full, it rolls over to 0. (R) (mandatory) (4 bytes) + +**Unexpected LTRs count:** This attribute records the number of unexpected LTRs received. When the counter is full, it rolls over to 0. (R) (mandatory) (4 bytes) + +**LBRs transmitted count:** This attribute records the number of LBRs transmitted. When the counter is full, it rolls over to 0. (R) (mandatory) (4 bytes) + +**Next loopback transaction identifier:** This attribute is the value of the transaction number sent in the next LBM to be transmitted. It is not required to persist over ONT initialization, but it should be initialized to a random value. It increments with each LBM sent, and rolls over when full. (R) (mandatory) (4 bytes) + +**Next link trace transaction identifier:** This attribute is the value of the transaction number sent in the next LTM to be transmitted. It is not required to persist over ONT initialization. It increments with each LTM sent, and rolls over when full. (R) (mandatory) (4 bytes) + +#### Actions + +#### Get, get next + +#### Notifications + +None. This managed entity does not generate AVCs because its attributes change frequently in real time, but are generally only of interest after the corresponding MEP declares an alarm. + +### 9.3.24 Dot1ag MEP CCM database + +This managed entity records the recent history of remote MEPs, as deduced by the local parent MEP. Because records are of variable length, and are constantly updated, a separate attribute is defined for each remote MEP. The dot1ag MEP CCM database is automatically created or deleted by the ONT at the time a MEP is created or deleted. + +As the reporter of ephemeral information, the dot1ag MEP CCM database ME is not persistent and is not included in MIB uploads. + +#### *Relationships* + +A dot1ag MEP CCM database ME is associated with a dot1ag MEP ME. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the dot1ag MEP ME. (R) (mandatory) (2 bytes) + +Each of the following RMEP database table attributes records information for one of the possible remote MEPs. It is expected that there will be only one remote MEP per MA in G-PON applications, but the ME is defined in a way that permits several RMEPs. The optional attributes are instantiated by the ONT when additional remote MEPs are provisioned on the local MEP. Remote MEP records appear in no particular order, and the order is not guaranteed to persist across ONT initializations. + +**RMEP 1 database table:** (R) (mandatory) (N bytes) + +**RMEP 2 database table:** (R) (optional) (N bytes) + +**RMEP 3 database table:** (R) (optional) (N bytes) + +**RMEP 4 database table:** (R) (optional) (N bytes) + +**RMEP 5 database table:** (R) (optional) (N bytes) + +**RMEP 6 database table:** (R) (optional) (N bytes) + +**RMEP 7 database table:** (R) (optional) (N bytes) + +**RMEP 8 database table:** (R) (optional) (N bytes) + +**RMEP 9 database table:** (R) (optional) (N bytes) + +**RMEP 10 database table:** (R) (optional) (N bytes) + +**RMEP 11 database table:** (R) (optional) (N bytes) + +**RMEP 12 database table:** (R) (optional) (N bytes) + +Each attribute is a record that comprises the following fields: + +**RMep identifier.** The MEP ID of the remote MEP. (2 bytes) + +**RMeP state.** An enumeration with the following meaning (1 byte): + +- 1 Idle. Momentary state during reset. +- 2 Start. The timer has not expired since the state machine was reset, but no valid CCM has yet been received. +- 3 Failed. The timer has expired since the state machine was reset and since a valid CCM was received. +- 4 Ok. The timer has not expired since a valid CCM was received. + +**Failed-ok time.** A timestamp, the value of the local ONT's SysUpTime at which the remote MEP state last entered either the failed or ok state. SysUpTime is a count of 10-ms intervals since ONT initialization. The value 0 if it has not been in either of these states since ONT initialization. (4 bytes) + +**MAC address.** The MAC address of the remote RMEP. If no CCM has been received from the remote MEP, this field has the value 0. (6 bytes) + +**RDI.** Boolean indicating whether the RDI bit in the most recently received CCM was set. (1 byte) + +**Port status.** The port status from the most recently received CCM, as defined in clause 21.5.4 of [b-IEEE 802.1ag]. The absence of a received port status TLV is indicated by the value 0. (1 byte) + +**Interface status.** The interface status from the most recently received CCM, as defined in clause 21.5.5 of [b-IEEE 802.1ag]. The absence of a received interface status TLV is indicated by the value 0. (1 byte) + +**Sender ID TLV.** This is the actual sender ID TLV from the most recently received CCM, as defined in clause 21.5.3 of [b-IEEE 802.1ag]. The absence of a received sender ID TLV is indicated by a single byte of value 0. (M bytes) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. The MEP CCM database table attributes do not generate AVCs because they change constantly in real time, usually in ways that are of no immediate interest. + +### **9.3.25 Dot1ag CFM stack** + +This managed entity reports the maintenance status of a bridge's port at any given time. An ONT that supports [b-IEEE 802.1ag] functionality automatically creates an instance of the dot1ag CFM stack ME for each MAC bridge or 802.1p mapper, depending on its provisioning model. + +The dot1ag CFM stack also lists any VLANs and bridge ports against which configuration errors are currently identified. The ONT should reject operations that create configuration errors. However, these errors can arise because of operations on other MEs that are not necessarily possible to detect during CFM configuration. + +#### Relationships + +An ONT that supports [b-IEEE 802.1ag] creates one instance of this ME for each MAC bridge or 802.1p mapper, depending on its provisioning model. It should not create an instance for an 802.1p mapper that is associated with a MAC bridge. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies an instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge service profile ME or an 802.1p mapper ME. It is expected that an ONT will implement CFM on bridges or on 802.1p mappers, but not both. For precision, the reference is disambiguated by the value of the layer 2 type pointer attribute. (R) (mandatory) (2 bytes) + +**Layer 2 type:** This attribute specifies whether the dot1ag CFM stack is associated with a MAC bridge service profile (value 0) or an 802.1p mapper (value 1). (R) (mandatory) (1 byte) + +**MP status table:** This attribute is a list of entries, each entry reporting one aspect of the maintenance status of one port. If a port is associated with more than one CFM maintenance entity, each is represented as a separate item in this table attribute; a port that has no current maintenance functions is not represented in the table (so the table may be empty). Each entry is defined as follows: + +**Port id:** The ME ID of the bridge port config data whose information is reported in this entry. If the layer 2 parent is an 802.1p mapper, a null pointer. (2 bytes) + +**Level:** The level at which the reported maintenance function exists, 0..7. (1 byte) + +**Direction:** The value 1 (down) or 2 (up). (1 byte) + +**VLAN ID:** If this table entry reports a maintenance function associated with a VLAN, this field contains the value of the primary VLAN ID. If no VLAN is associated with this entry, this field contains the value 0. (2 bytes) + +**MD:** A pointer to the associated dot1ag maintenance domain ME. If no MD is associated with this entry, a null pointer. (2 bytes) + +**MA:** A pointer to the associated dot1ag maintenance association ME. If no MA is associated with this entry, a null pointer. (2 bytes) + +**MEP ID:** If this table entry reports a MEP, this field contains the value of its MEP ID (range 1..8191). If this table entry reports an MHF, this field contains the value 0. (2 bytes) + +**MAC address:** The MAC address of the maintenance point. (6 bytes) +(R) (mandatory) (18N bytes) + +**Configuration error list table:** This attribute is based on the [b-IEEE 802.1ag] configuration error list. It is a list of entries, each entry reporting a VLAN and a bridge port against which a configuration error has been detected. The table may be empty at any given time. Entries are defined as follows: + +**VLAN ID:** If this table entry reports a maintenance function associated with a VLAN, this field contains the value of the VLAN ID in error. If no VLAN is associated with this entry, this field contains the value 0. (2 bytes) + +**Port id:** A pointer to the bridge port config data whose information is reported in this entry. If the layer 2 parent is an 802.1p mapper, a null pointer. (2 bytes) + +**Detected configuration error:** A bit mask with the following meanings. A list entry exists if and only if at least one of these bits is set. Definitions appear in clause 22.2.4 of [b-IEEE 802.1ag] (1 byte): + +- 0x01 CFM leak. MA x is associated with a specific VID list, one or more of the VIDs in MA x can pass through the bridge port, no up MEP is configured for MA x on the bridge port, no down MEP is configured on any bridge port for MA x, and some other MA y, at a higher MD level than MA x, and associated with at least one of the VID(s) also in MA x, does have an MEP configured on the bridge port. +- 0x02 Conflicting VIDs. MA x is associated with a specific VID list, an up MEP is configured on MA x on the bridge port, and some other MA y, associated with at least one of the VID(s) also in MA x, and at the same MD level as MA x, also has an up MEP configured on some bridge port. +- 0x04 Excessive levels. The number of different MD levels at which MIPs are to be created on this port exceeds the bridge's capabilities. +- 0x08 Overlapped levels. An MEP is created for one VID at one MD level, but an MEP is also configured on another VID at that MD level or higher, exceeding the bridge's capabilities. + +(R) (mandatory) (5N bytes) + +#### Actions + +#### Get, get next + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|-------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1..2 | Reserved | | +| 3 | Config error list table | This AVC indicates that an entry in the configuration error list table has been added or removed. It may be advisable for the OLT to audit the configuration of related MEs. | +| 4..16 | Reserved | | + +### 9.3.26 Dot1ag chassis-management info + +This managed entity represents the system-level chassis ID and/or management address for [b-IEEE 802.1ag] CFM messages, and potentially for other 802-based functions. Although [b-IEEE 802.1AB] allows for several management addresses (synonyms in different formats, or with granularity to the component level), [b-IEEE 802.1ag] does not provide for more than one. Nor + +is it expected that an ONT would require more than one format. Accordingly, this managed entity provides for only one. + +According to sender ID permission attributes in several dot1ag managed entities, transmitted [b-IEEE 802.1ag] CFM messages may include either or both of the chassis ID or management address fields. [b-IEEE 802.1ag] requires that CCMs not exceed 128 bytes, of which 74 are separately allocated to other purposes; the sender ID TLV, if present, must accommodate this requirement. The chassis info and management info must fit, with a minimum of 4 additional overhead bytes, into the remaining 54 bytes. This limit is exploited in defining the maximum size of the managed entity's attributes. + +#### Relationships + +If an ONT supports [b-IEEE 802.1ag] functionality, it automatically creates an instance of this managed entity. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies this managed entity. There is at most one instance, whose value is 0. (R) (mandatory) (2 bytes) +- Chassis ID length:** The length of the chassis ID attribute (not including the chassis ID subtype attribute), default value 0. (R, W) (mandatory) (1 byte) +- Chassis ID subtype:** The format of the chassis ID attribute, default value 7, as defined in [b-IEEE 802.1AB]: + +| | | | +|---|-------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Chassis component | A particular instance of the entPhysicalAlias object (defined in [b-IETF RFC 2737]) for a chassis component. | +| 2 | Interface alias | A particular instance of the ifAlias object (defined in [b-IETF RFC 2863]) for an interface on the containing chassis. | +| 3 | Port component | A particular instance of the entPhysicalAlias object (defined in [b-IETF RFC 2737]) for a port or backplane component within the containing chassis. | +| 4 | MAC address | A particular unicast source address (encoded in network byte order and [b-IEEE 802.3] canonical bit order), of a port on the containing chassis as defined in [b-IEEE 802]. | +| 5 | Network address | A particular network address, encoded in network byte order, associated with one or more ports on the containing chassis. The first octet contains the IANA address family numbers enumeration value for the specific address type, and octets 2 through N contain the network address value in network byte order. | +| 6 | Interface name | A particular instance of the ifName object (defined in [b-IETF RFC 2863]) for an interface on the containing chassis. | +| 7 | Local | Locally assigned chassis ID. | + +(R, W) (mandatory) (1 byte) + +**Chassis ID part 1, Chassis ID part 2:** These two attributes may be regarded as an octet string of up to 50 bytes whose length is given by the chassis ID length attribute and whose value is the left-justified chassis ID. (R, W) (mandatory) (25 bytes \* 2 attributes) + +**Management address domain length:** The length of the management address domain attribute, default value 0. If this attribute has the value 0, all of the other management address attributes are undefined. (R, W) (mandatory) (1 byte) + +| | | +|------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Management address domain 1, Management address domain 2: | These two attributes may be regarded as an octet string of up to 50 bytes whose length is given by the management address domain length attribute and whose value is the left-justified management address domain. The attribute is coded as an object identifier (OID) per [b-ITU-T X.690], referring to a TDomain as defined in [b-IETF RFC 2579]. Typical values include snmpUDPDomain (from SNMPv2-TM, [b-IETF RFC 3417]) and snmpIeee802Domain (from SNMP-IEEE802-TM-MIB, [b-IETF RFC 4789]). (R, W) (mandatory) (25 bytes * 2 attributes) | +| Management address length: | The length of the management address attribute, default value 0. (R, W) (mandatory) (1 byte) | +| Management address 1, Management address 2: | These two attributes may be regarded as an octet string of up to 50 bytes whose length is given by the management address length attribute and whose value is the left-justified management address. (R, W) (mandatory) (25 bytes * 2 attributes) | + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.3.27 Multicast operations profile** + +This managed entity expresses multicast policy. A multi-dwelling unit ONU may have several such policies, which are linked to subscribers as required. Some of the attributes configure IGMP snooping and proxy parameters, in case the defaults do not suffice, as described in [b-IETF RFC 2236], [b-IETF RFC 3376], [b-IETF RFC 3810] and [b-IETF RFC 2933]. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the multicast subscriber config info ME. + +#### *Attributes* + +| | | +|---------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. The values 0 and 0xffff are reserved. (R, Set-by-create) (mandatory) (2 bytes) | +| IGMP version: | This attribute specifies the version of IGMP to be supported. Support of a given version implies compatible support of previous versions. If the ONT cannot support the version requested, it should deny an attempt to write or create the ME. The default value is 2. (R, W, Set-by-create) (mandatory) (1 byte)
1 IGMP version 1 (deprecated).
2 IGMP version 2.
3 IGMP version 3.
Other values reserved. | + +| | | +|-----------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| IGMP function: | This attribute enables an IGMP function. The default value 0 specifies transparent IGMP snooping only. The value 1 specifies snooping with proxy reporting (SPR); the value 2 specifies IGMP proxy. The function must be consistent with the capabilities specified by the other IGMP configuration attributes. (R, W, Set-by-create) (mandatory) (1 byte) | +| Immediate leave: | This Boolean attribute enables the immediate leave function. The default value false disables immediate leave; true enables immediate leave. (R, W, Set-by-create) (mandatory) (1 byte) | +| Upstream IGMP TCI: | Under control of the upstream IGMP tag control attribute, the upstream IGMP TCI attribute defines a VLAN ID and P-bits to add to upstream IGMP messages. (R, W, Set-by-create) (optional) (2 bytes) | +| Upstream IGMP tag control: | This attribute controls the upstream IGMP TCI attribute. (R, W, Set-by-create) (optional) (1 byte) | + +| Value | Meaning | +|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Pass upstream IGMP traffic transparently, neither adding, stripping nor modifying tags that may be present. | +| 1 | Add a VLAN tag (including P-bits) to upstream IGMP traffic. The VLAN is specified by the upstream IGMP TCI attribute. | +| 2 | Replace the entire TCI (VLAN ID plus P-bits) on upstream IGMP traffic. The new tag is specified by the upstream IGMP TCI attribute. | +| 3 | Replace only the VLAN ID on upstream IGMP traffic, retaining the original CFI and P-bits. The new VLAN ID is specified by the VLAN field of the upstream IGMP TCI attribute. | +| Others | Reserved. | + +**Upstream IGMP rate:** This attribute limits the maximum rate of upstream IGMP traffic. Traffic in excess of this limit is silently discarded. The attribute value is specified in messages/second. The default value 0 imposes no rate limit on this traffic. (R, W, Set-by-create) (optional) (4 bytes) + +**Dynamic access control list table:** This attribute is a list that specifies one or more multicast group address ranges. The ONT is expected to silently discard IGMP join requests for groups that are not listed in this table. + +Each list entry is a vector of eight components: + +- Table index (2 bytes) + +The first two bytes of each entry are treated as the index of the table. It is the responsibility of the OLT to assign and track table indices and content. The ONT should deny set operations that create range overlaps. + +The two MSBs of this field determine the meaning of a set operation. These bits are returned as 00 during get next operations. + +| Bits 16..15 | Meaning | +|-------------|------------------------------------------------------------------------------------------| +| 00 | Reserved. | +| 01 | Write this entry into the table. Overwrite any existing entry with the same table index. | +| 10 | Delete this entry from the table. The remaining fields are not meaningful. | +| 11 | Clear all entries from the table. The remaining fields are not meaningful. | + +- GEM port-ID (2 bytes) +- VLAN ID. This field specifies the VLAN carrying the multicast group downstream. The VLAN ID resides in the 12 least significant bits; the remaining bits are set to 0 and not used. The value 0x0000 designates an untagged downstream flow. (2 bytes) +- Source IP address. The value 0.0.0.0 specifies that source IP address is to be ignored. (4 bytes) +- Destination IP address of the start of the multicast range. (4 bytes) +- Destination IP address of the end of the multicast range. (4 bytes) +- Imputed group bandwidth. Expressed in bytes per second, the imputed group bandwidth is used to decide whether or not to honour a join request in the presence of a max multicast bandwidth limit. The default value 0 effectively allows this table entry to avoid max bandwidth limitations. (4 bytes) +- Reserved, set to 0. (2 bytes) + +A single multicast group may be specified by setting start and end destination IP addresses to the same value. + +(R, W) (mandatory) (24N bytes, where N is the number of entries in the table) + +**Discussion of table size:** While theoretically, this table could contain 16,384 entries, real-world applications are not expected to require large tables. It is instead anticipated that the table will list a moderate number of contiguous ranges, each of which shares a common GEM port, VLAN, IP source and imputed bandwidth. + +**Static access control list table:** This attribute is a list that specifies one or more multicast group address ranges. Groups defined in this list are multicast on the associated UNI(s) unconditionally, that is, without the need for an IGMP join. The bandwidth of static multicast groups is not included in the current multicast bandwidth measurement maintained by the multicast subscriber monitor managed entity. If a join message is always expected, this table may be empty. Table entries have the same format as those in the dynamic access control list table. (R, W) (mandatory) (24N bytes, where N is the number of entries in the table) + +- Lost groups list table:** This attribute is a list of groups from the dynamic access control list table for which there is an active join, but no downstream flow is present, possibly because of source failure, but also possibly because of misconfiguration somewhere upstream. After a join, the ONT should wait a reasonable time for upstream processing before declaring a group to be lost. Each entry is a vector of the following components: +- VLAN ID, 0 if not used. (2 bytes) + - Source IP address, 0.0.0.0 if not used. (4 bytes) + - Multicast destination IP address. (4 bytes) +- (R) (optional) (10N bytes) +- Robustness:** This attribute allows tuning for possible packet loss in the network. The default value 0 causes the ONT to follow the IETF recommendation to copy the robustness value from query messages originating further upstream. (R, W, Set-by-create) (optional) (1 byte) +- Querier IP address:** This attribute specifies the IP address to be used by a proxy querier. Although it is not a legitimate IP address, the default value 0.0.0.0 is legal in this case (see [b-IETF RFC 4541]). (R, W, Set-by-create) (optional) (4 bytes) +- Query interval:** This attribute specifies the interval between general queries in seconds. The default is 125 seconds. (R, W, Set-by-create) (optional) (4 bytes) +- Query max response time:** This attribute is the max response time added by the proxy into general query messages directed to UNIs. It is expressed in tenths of seconds, with a default of 100 (10 seconds). (R, W, Set-by-create) (optional) (4 bytes) +- Last member query interval:** This attribute specifies the max response time inserted into group-specific queries sent to UNIs in response to group leave messages. It is also the repetition rate of [robustness] transmissions of the query. It is specified in tenths of seconds, with a default of 10 (1 second). (R, W) (optional) (4 bytes) + +#### Actions + +**Create, delete, get, get next, set** + +#### Notifications + +| Alarm | | | +|----------|------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Number | Alarm | Description | +| 0 | Lost multicast group | Indicates that for one or more multicast groups, there is an active join, but no downstream flow is present. This alarm is equivalent to a non-zero number of entries in the lost groups list table attribute. When the alarm is active, the OLT may use the table to retrieve the details of the lost group(s). | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.3.28 Multicast subscriber config info + +This managed entity organizes data associated with multicast management at subscriber ports of 802.1 bridges, including 802.1p mappers when the provisioning model is mapper-based rather than + +bridge-based. Instances of this managed entity are created and deleted by the OLT. Because of backward compatibility considerations, a subscriber port without an associated multicast subscriber config info ME would be expected to support unrestricted multicast access; this ME may therefore be viewed as restrictive, rather than permissive. + +#### *Relationships* + +An instance of this managed entity is associated with one instance of the MAC bridge port configuration data or the 802.1p mapper service profile. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data or 802.1p mapper ME. (R, Set-by-create) (mandatory) (2 bytes) +- ME type:** This attribute indicates the type of the ME implicitly linked by the managed entity id attribute. +- 0 MAC bridge port config data. + - 1 802.1p mapper service profile. +- (R, W, Set-by-create) (mandatory) (1 byte) +- Multicast operations profile pointer:** This attribute points to an instance of the multicast operations profile. (R, W, Set-by-create) (mandatory) (2 bytes) +- Max simultaneous groups:** This attribute specifies the maximum number of dynamic multicast groups that may be replicated to the client port at any one time. The default value 0 specifies that no administrative limit is to be imposed. (R, W, Set-by-create) (optional) (2 bytes) +- Max multicast bandwidth:** This attribute specifies the maximum imputed dynamic bandwidth, in bytes per second, that may be delivered to the client port at any one time. The default value 0 specifies that no administrative limit is to be imposed. (R, W, Set-by-create) (optional) (4 bytes) +- Bandwidth enforcement:** The default value of this Boolean attribute is false, and specifies that attempts to exceed the max multicast bandwidth be counted but honoured. The value true specifies that such attempts be counted and denied. The imputed bandwidth value is taken from the dynamic access control list table, both for a new join request and for pre-existing groups. (R, W, Set-by-create) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.3.29 Multicast subscriber monitor** + +This managed entity provides the current status of each port with respect to its multicast subscriptions. It may be useful for status monitoring or debugging purposes. The status table includes all groups currently subscribed by the port, both dynamic and static. + +#### *Relationships* + +Instances of this managed entity are created and deleted at the request of the OLT. One instance may exist for each 802.1 UNI configured to support multicast subscription. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the MAC bridge port configuration data or 802.1p mapper ME. (R, Set-by-create) (mandatory) (2 bytes) + +**ME type:** This attribute indicates the type of the ME implicitly linked by the managed entity id attribute. + +- 0 MAC bridge port config data. +- 1 802.1p mapper service profile. + +(R, W, Set-by-create) (mandatory) (1 byte) + +**Current multicast bandwidth:** This attribute is the ONT's best effort estimate of the actual bandwidth currently being delivered over all dynamic multicast groups. (R) (optional) (4 bytes) + +**Join messages counter:** This attribute counts the number of times the corresponding subscriber sent a join message that was accepted. When full, the counter rolls over to 0. (R) (optional) (4 bytes) + +**Bandwidth exceeded counter:** This attribute counts the number of join messages that did, or would have, exceeded the max multicast bandwidth, whether accepted or denied. When full, the counter rolls over to 0. (R) (optional) (4 bytes) + +**Active group list table:** This attribute lists the groups from the dynamic access control list table that are currently being actively forwarded, along with the actual bandwidth of each. If a join has been recognized from more than one IP source address for a given group on this UNI, there will be one table entry for each. Each table entry has the form: + +- VLAN ID, 0 if not used. (2 bytes) +- Source IP address, 0.0.0.0 if not used. (4 bytes) +- Multicast destination IP address. (4 bytes) +- Best efforts actual bandwidth estimate, bytes per second. (4 bytes) +- Client (set-top box) IP address, that is, the IP address of the device currently joined. (4 bytes) +- Time since the most recent join of this client to the IP channel, in seconds. (4 bytes) +- Reserved. (2 bytes) + +(R) (mandatory) (24N bytes) + +#### *Actions* + +**Create, delete, get, get next, set** + +#### *Notifications* + +None. + +## **9.4 Layer 3 data services** + +This clause defines managed entities associated with layer 3 services, as shown in Figure 9.4-1. + +![Diagram of managed entities associated with layer 3 services. The central entity is 9.4.1: IP router service profile. It is pointed to by GEM interworking TP and Multicast GEM interworking TP. It has a one-to-many relationship (N) with 9.4.3: IP port config data. 9.4.3 points to GEM interworking TP, MAC bridge port, and Any other L2 termination point. 9.4.3 has a one-to-one relationship (1) with 9.4.10: ARP service profile. 9.4.10 is pointed to by MGC config data, Pseudowire TP, and SIP agent config data. 9.4.10 has a one-to-many relationship (N) with 9.4.14: TCP/UDP config data. 9.4.14 points to 9.4.12: IP host config data. 9.4.12 is pointed to by 9.4.13: IP host PM history data. 9.4.1: IP router service profile is also pointed to by 9.4.2: IP router config data, 9.4.4: IP route table, 9.4.5: IP static routes, 9.4.6: IP router PM history data 1, 9.4.7: PM 2, 9.4.8: ICMP PM history data 1, 9.4.9: PM 2, and 9.4.11: ARP config data. 9.4.5 points to GEM interworking TP.](f512ae9c630f2fb53197fa77a1bda0e8_img.jpg) + +``` + +graph TD + subgraph LeftColumn + L1[9.4.1: IP router service profile] + L2[9.4.3: IP port config data] + L3[9.4.10: ARP service profile] + L4[9.4.14: TCP/UDP config data] + end + subgraph RightColumn + R1[9.4.2: IP router config data] + R2[9.4.4: IP route table] + R3[9.4.5: IP static routes] + R4[9.4.6: IP router PM history data 1 +9.4.7: PM 2] + R5[9.4.8: ICMP PM history data 1 +9.4.9: PM 2] + R6[9.4.11: ARP config data] + R7[9.4.12: IP host config data] + R8[9.4.13: IP host PM history data] + end + L1 -- "Pointed to by: +GEM interworking TP +Multicast GEM interworking TP" --- L1 + L1 -- "N" --> L2 + L2 -- "Points to: +GEM interworking TP +MAC bridge port +Any other L2 termination point" --- L2 + L2 -- "1" --> L3 + L3 -- "Pointed to by: +MGC config data +Pseudowire TP +SIP agent config data" --- L3 + L3 -- "N" --> L4 + L4 --> R7 + R7 --- R8 + R1 -.-> L1 + R2 -.-> L1 + R3 -.-> L1 + R3 -- "Points to: +GEM interworking TP" --> R3_Target[GEM interworking TP] + R4 -.-> L1 + R5 -.-> L1 + R6 -.-> L1 + +``` + +Diagram of managed entities associated with layer 3 services. The central entity is 9.4.1: IP router service profile. It is pointed to by GEM interworking TP and Multicast GEM interworking TP. It has a one-to-many relationship (N) with 9.4.3: IP port config data. 9.4.3 points to GEM interworking TP, MAC bridge port, and Any other L2 termination point. 9.4.3 has a one-to-one relationship (1) with 9.4.10: ARP service profile. 9.4.10 is pointed to by MGC config data, Pseudowire TP, and SIP agent config data. 9.4.10 has a one-to-many relationship (N) with 9.4.14: TCP/UDP config data. 9.4.14 points to 9.4.12: IP host config data. 9.4.12 is pointed to by 9.4.13: IP host PM history data. 9.4.1: IP router service profile is also pointed to by 9.4.2: IP router config data, 9.4.4: IP route table, 9.4.5: IP static routes, 9.4.6: IP router PM history data 1, 9.4.7: PM 2, 9.4.8: ICMP PM history data 1, 9.4.9: PM 2, and 9.4.11: ARP config data. 9.4.5 points to GEM interworking TP. + +**Figure 9.4-1 – Managed entities associated with layer 3 services** + +### 9.4.1 IP router service profile + +This managed entity models an IP router as a whole. It organizes data that affects all ports on the router. An instance of this managed entity is created and deleted by the OLT. + +#### Relationships + +One or more instances of this managed entity may be associated with a real or virtual cardholder (slot) that supports the router function. Any number of router ports may be associated with the router through IP port config data MEs. + +The router itself is configured and monitored through implicitly linked instances of the IP router config data, IP route table, IP static routes and IP and ICMP PM history data MEs. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The first byte is the slot id (defined in clause 9.1.5). If the ONT is integrated, its value is 0. The second byte is the router group id. (R, Set-by-create) (mandatory) (2 bytes) +- Forwarding ind:** The Boolean value true globally enables forwarding of IP packets (packets may still be discarded because of other settings). The value false disables IP forwarding. (R, W, Set-by-create) (mandatory) (1 byte) +- Proxy ARP ind:** The Boolean value true enables proxy ARP. The value false disables proxy ARP. (R, W, Set-by-create) (mandatory) (1 byte) +- Directed broadcast ind:** The Boolean value true enables relaying of directed broadcast packets. (R, W, Set-by-create) (mandatory) (1 byte) + +| | | +|----------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------| +| Upstream multicast filtering: | This attribute specifies whether upstream IP multicast packets are forwarded (0) or filtered (1). (R, W, Set-by-create) (mandatory) (1 byte) | +| Downstream multicast filtering: | This attribute specifies whether downstream IP multicast packets are forwarded (0) or filtered (1). (R, W, Set-by-create) (mandatory) (1 byte) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.4.2 IP router configuration data** + +This managed entity records data associated with an IP router configuration. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of the associated IP router service profile. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the IP router service profile. + +#### *Attributes* + +| | | +|---------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R) (mandatory) (2 bytes) | +| Ip reasm timeout: | This attribute indicates the maximum number of seconds that received fragments are held while they are awaiting reassembly at this router. (R) (mandatory) (4 bytes) | + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.4.3 IP port configuration data** + +This managed entity organizes data associated with IP port provisioning. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +Any number of instances of this managed entity may be associated with an IP router service profile and an ARP service profile. Each IP port instance is associated with zero or one instance of a GEM interworking termination point or native LAN (e.g., Ethernet) PPTP. + +#### *Attributes* + +| | | +|---------------------------|-------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| Port num: | This attribute numbers the port. (R, W, Set-by-create) (mandatory) (1 byte) | + +| | | +|------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TP type: | This attribute specifies the type of termination point associated with this IP port.
1 PPTP Ethernet UNI.
2 GEM interworking TP.
3 MAC bridge port configuration data.
4 802.1p mapper service profile.
5 Physical path termination point xDSL UNI.
6 Multicast GEM interworking termination point.
7 Physical path termination point MoCA UNI.
8 Physical path termination point 802.11 UNI.
9 Ethernet flow termination point.
(R, W, Set-by-create) (mandatory) (1 byte) | +| TP pointer: | This attribute points to the instance of the TP associated with this port. The type of the associated TP is determined by the TP type attribute. The value 0xFFFF is a null pointer.
NOTE – When the TP type is xDSL, the two most significant bits may be used to indicate a bearer channel. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Port address: | This attribute specifies the provisioned IP address. The value 0 indicates that no IP address is assigned to the port. (R, W, Set-by-create) (mandatory) (4 bytes) | +| Port mask: | This attribute specifies the IP address mask associated with the port. The value 0 indicates that no address mask is assigned to this port. (R, W, Set-by-create) (mandatory) (4 bytes) | +| Unnumbered: | The Boolean value true specifies that this IP port is unnumbered. The value false specifies that the port has an IP address. (R, W, Set-by-create) (mandatory) (1 byte) | +| Administrative state: | This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this port are blocked, and alarms, TCAs and AVCs for this port and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W, Set-by-create) (mandatory) (1 byte) | +| Port state: | This attribute provides status information on the port. Valid values are up (0) and down (1). (R) (mandatory) (1 byte) | +| Allow remote access: | The Boolean value true specifies that remote access is enabled for this IP port. The value false disables remote access. (R, W, Set-by-create) (mandatory) (1 byte) | +| Router id pointer: | This attribute points to an instance of the IP router service profile. The value 0xFFFF indicates that this port is not associated with an IP router. (R, W, Set-by-create) (mandatory) (2 bytes) | +| ARP pointer: | This attribute points to the instance of ARP service profile associated with the port. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Encapsulation method: | This attribute is not used. If it is present, its value should be set to 1. (R, W) (optional) (1 byte) | + +*Actions* + +**Create, delete, get, set** + +*Notifications* + +None. + +### 9.4.4 IP route table + +This managed entity records data associated with IP routes. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of an IP router service profile. + +*Relationships* + +An instance of this managed entity is associated with an instance of the IP router service profile. + +*Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R) (mandatory) (2 bytes) +- Ip route number:** This attribute indicates the number of current routes in the route table. Its initial value is 0. (R) (mandatory) (2 bytes) +- Ip route table max size:** This attribute indicates the maximum number of routes that can be stored in the route table. Its value is determined by the ONT implementation. (R) (mandatory) (2 bytes) +- Ip route table:** This attribute lists current routes in the route table. An entry contains the following fields: +- | | | +|----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------| +| route id: | A unique identifier of a route within the route table. (2 bytes) | +| destination address: | The IP destination address of this route. (4 bytes) | +| destination address mask: | The address mask associated with the destination address. (4 bytes) | +| tos: | TOS value defined in [IETF RFC 2096] (ipCidrRouteTos) for use with policy routing; otherwise 0. (1 byte) | +| next hop: | The address of the next router on remote routes. (4 bytes) | +| output port: | The number of the IP port through which the next hop of this route should be reached. (1 byte) | +| route type: | The type of route as defined in [IETF RFC 2096] (ipCidrRouteType). (1 byte) | +| route protocol: | The routing mechanism via which this route was learned, as defined in [IETF RFC 2096] (ipCidrRouteProto). For example, static route is 3. (1 byte) | + +- route age:** The number of seconds since this route was last updated or otherwise determined to be correct. Static routes may return the value 0xFFFF FFFF. (4 bytes) +- metric:** The primary (first 4 bytes) and secondary (second 4 bytes) routing metrics for this route. The semantics of this metric are determined by the routing protocol specified in the route's route-protocol value. If part of this metric is not used, its value should be set to 0xFFFF FFFF. (2\* 4 bytes) +- (R) (mandatory) (30N bytes, where N is the number of routes) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### **9.4.5 IP static routes** + +This managed entity stores IP static routes. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of an instance of the IP router service profile. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the IP router service profile. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R) (mandatory) (2 bytes) +- Ip static route table max size:** This attribute indicates the maximum number of routes that can be stored in the static route table. Its value is determined by the ONT implementation. (R) (mandatory) (2 bytes) +- Ip static route table:** This attribute stores static routes. A route contains several fields, defined below. +- route id:** A unique identifier of a route within the static route table. (1 byte) + - action:** Remove (0) or add (1) this route, meaningful during the set action only. When a static route is being removed, the route is identified by the route id field. (1 byte) + - destination address:** The IP destination address of this route. This field may be set to the default route address 0.0.0.0. (4 bytes) + - destination address mask:** The address mask associated with the destination address. (4 bytes) + - next hop:** The address of the next router on remote routes. This field is not used when the next hop is reached through an unnumbered link. (4 bytes, 0xFFFF FFFF when not used) + +| | | +|---------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| output port: | The number of the IP port through which the next hop should be reached. This field is used when the next hop is reached through an unnumbered link and when a static route is set to support a fully meshed network. (1 byte, 0xFF when not used) | +| iw pointer: | Pointer to the instance of the GEM interworking termination point that identifies a link of a fully meshed network being set by this attribute. The value 0 is a null pointer. (2 bytes) | +| metric: | The routing metric for this route. (4 bytes)
(R, W) (mandatory) (21N bytes, where N is the number of routes) | + +#### *Actions* + +#### **Get, get next, set** + +#### *Notifications* + +None. + +### **9.4.6 IP router performance monitoring history data 1** + +This managed entity collects some of the IP-related performance monitoring data at an IP router. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the IP router service profile. + +#### *Attributes* + +| | | +|-----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Ip in receives counter: | This attribute counts packets received from interfaces, including those with errors. (R) (mandatory) (4 bytes) | +| Ip in hdr errors counter: | This attribute counts packets discarded due to errors in their IP headers, including bad checksums, version number mismatch, other format errors, time-to-live exceeded, errors discovered in processing IP options, etc. (R) (mandatory) (4 bytes) | +| Ip in addr errors counter: | This attribute counts packets discarded because their destination IP addresses were not valid for this router. This includes invalid addresses (e.g., 0.0.0.0) and addresses of unsupported classes (e.g., class E). (R) (mandatory) (4 bytes) | + +- Ip forw packets counter:** This attribute counts packets whose final IP destination was not this router, as a result of which an attempt was made to forward them. (R) (mandatory) (4 bytes) +- Ip in unknown protos counter:** This attribute counts packets that were locally destined and received successfully but discarded because of an unknown or unsupported protocol. (R) (mandatory) (4 bytes) +- Ip in discards counter:** This attribute counts input packets for which no problems were encountered to prevent their continued processing, but which were nevertheless discarded, e.g., for lack of buffer space. It does not include packets discarded while awaiting re-assembly. (R) (mandatory) (4 bytes) +- Ip in delivers counter:** This attribute counts input packets successfully delivered to local IP application protocols, including ICMP. (R) (mandatory) (4 bytes) +- Ip out requests counter:** This attribute counts packets originated by local IP application protocols, including ICMP. This does not include packets counted in ip forw packets counter. (R) (mandatory) (4 bytes) +- Ip out discards counter:** This attribute counts output packets for which no problem was encountered to prevent transmission to their destination, but which were nevertheless discarded, e.g., for lack of buffer space. It includes packets counted in ip forw packets counter if any such packets met this discard criterion. (R) (mandatory) (4 bytes) +- Ip out no routes counter:** This attribute counts packets discarded because no forwarding route was available. It includes any packets counted in ip forw packets counter that met this no-route criterion. It also includes packets that a host could not route because all of its default gateways were down. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +**Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Ip in receives | 1 | +| 1 | Ip in hdr | 2 | +| 2 | Ip in addr | 3 | +| 3 | Ip forw packets | 4 | +| 4 | Ip in unknown protos | 5 | +| 5 | Ip in discards | 6 | +| 6 | Ip in delivers | 7 | +| 7 | Ip out requests | 8 | +| 8 | Ip out discards | 9 | +| 9 | Ip out no routes | 10 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.4.7 IP router performance monitoring history data 2 + +This managed entity collects additional IP-related performance monitoring data at an IP router. An instance of this managed entity is created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the IP router service profile. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Ip reasm reqds counter:** This attribute counts received packets that needed to be reassembled. (R) (mandatory) (4 bytes) +- Ip reasm OKs counter:** This attribute counts packets successfully re-assembled. (R) (mandatory) (4 bytes) +- Ip reasm fails counter:** This attribute counts failures of the IP re-assembly algorithm for any reason: timed out, errors, etc. This is not necessarily a count of discarded IP fragments, since some algorithms (notably the algorithm in [IETF RFC 815]) can lose track of the number of fragments by combining them as they are received. (R) (mandatory) (4 bytes) +- Ip frag OKs counter:** This attribute counts packets that were successfully fragmented. (R) (mandatory) (4 bytes) +- Ip frag fails counter:** This attribute counts packets that were discarded because they needed to be fragmented but could not be, e.g., because the do not fragment flag was set. (R) (mandatory) (4 bytes) +- Ip frag creates counter:** This attribute counts IP fragments that were generated as a result of fragmentation. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Ip reasm reqds | 1 | +| 1 | Ip reasm OKs | 2 | +| 2 | Ip reasm fails | 3 | +| 3 | Ip frag OKs | 4 | +| 4 | Ip frag fails | 5 | +| 5 | Ip frag creates | 6 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.4.8 ICMP performance monitoring history data 1 + +This managed entity contains performance monitoring related to received ICMP messages at an IP router. An instance of this managed entity is created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity is associated with an instance of the IP router service profile. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) +- Icmp in msgs counter:** This attribute counts received ICMP messages. It includes those also counted by icmp in errors counter. (R) (mandatory) (4 bytes) +- Icmp in errors counter:** This attribute counts ICMP messages that were received but had ICMP-specific errors: bad ICMP checksums, bad length, etc. (R) (mandatory) (4 bytes) +- Icmp in dest unreachs counter:** This attribute counts received ICMP destination unreachable messages. (R) (mandatory) (4 bytes) +- Icmp in time excds counter:** This attribute counts received ICMP time exceeded messages. (R) (mandatory) (4 bytes) +- Icmp in parm probs counter:** This attribute counts received ICMP parameter problem messages. (R) (mandatory) (4 bytes) +- Icmp in src quenchs counter:** This attribute counts received ICMP source quench messages. (R) (mandatory) (4 bytes) +- Icmp in redirects counter:** This attribute counts received ICMP redirect messages. (R) (mandatory) (4 bytes) + +- Icmp in echos counter:** This attribute counts received ICMP echo (request) messages. (R) (mandatory) (4 bytes) +- Icmp in echo reps counter:** This attribute counts received ICMP echo reply messages. (R) (mandatory) (4 bytes) +- Icmp in timestamps counter:** This attribute counts received ICMP timestamp (request) messages. (R) (mandatory) (4 bytes) +- Icmp in timestamp reps counter:** This attribute counts received ICMP timestamp reply messages. (R) (mandatory) (4 bytes) +- Icmp in addr masks counter:** This attribute counts received ICMP address mask (request) messages. (R) (mandatory) (4 bytes) +- Icmp in addr mask reps counter:** This attribute counts received ICMP address mask reply messages. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Icmp in msgs | 1 | +| 1 | Icmp in errors | 2 | +| 2 | Icmp in dest unreachs | 3 | +| 3 | Icmp in time excds | 4 | +| 4 | Icmp in parm probs | 5 | +| 5 | Icmp in src quenchs | 6 | +| 6 | Icmp in redirects | 7 | +| 7 | Icmp in echos | 8 | +| 8 | Icmp in timestamps | 9 | +| 9 | Icmp in timestamp reps | 10 | +| 10 | Icmp in addr masks | 11 | +| 11 | Icmp in addr mask reps | 12 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### **9.4.9 ICMP performance monitoring history data 2** + +This managed entity contains performance monitoring related to transmitted ICMP messages at an IP router. An instance of this managed entity is created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the IP router service profile. + +#### *Attributes* + +| | | +|-----------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP router service profile. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Icmp out msgs counter: | This attribute counts ICMP messages that this router attempted to send. It includes those also counted by icmp out errors counter. (R) (mandatory) (4 bytes) | +| Icmp out errors counter: | This attribute counts ICMP messages that this router did not send due to problems within ICMP, such as a lack of buffers. This value should not include errors outside the ICMP layer such as the inability of IP to route the resultant packet. In some implementations, there may be no types of error that contribute to this counter. (R) (mandatory) (4 bytes) | +| Icmp out dest unreachs counter: | This attribute counts transmitted ICMP destination unreachable messages. (R) (mandatory) (4 bytes) | +| Icmp out time excds counter: | This attribute counts transmitted ICMP time exceeded messages. (R) (mandatory) (4 bytes) | +| Icmp out parm probs counter: | This attribute counts transmitted ICMP parameter problem messages. (R) (mandatory) (4 bytes) | +| Icmp out src quenchs counter: | This attribute counts transmitted ICMP source quench messages. (R) (mandatory) (4 bytes) | +| Icmp out redirects counter: | This attribute counts transmitted ICMP redirect messages. (R) (mandatory) (4 bytes) | +| Icmp out echos counter: | This attribute counts transmitted ICMP echo (request) messages. (R) (mandatory) (4 bytes) | +| Icmp out echo reps counter: | This attribute counts transmitted ICMP echo reply messages. (R) (mandatory) (4 bytes) | +| Icmp out timestamps counter: | This attribute counts transmitted ICMP timestamp (request) messages. (R) (mandatory) (4 bytes) | +| Icmp out timestamp reps counter: | This attribute counts transmitted ICMP timestamp reply messages. (R) (mandatory) (4 bytes) | +| Icmp out addr masks counter: | This attribute counts transmitted ICMP address mask (request) messages. (R) (mandatory) (4 bytes) | +| Icmp out addr mask reps counter: | This attribute counts transmitted ICMP address mask reply messages. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Icmp out msgs | 1 | +| 1 | Icmp out errors | 2 | +| 2 | Icmp out dest unreachs | 3 | +| 3 | Icmp out time excds | 4 | +| 4 | Icmp out parm probs | 5 | +| 5 | Icmp out src quenchs | 6 | +| 6 | Icmp out redirects | 7 | +| 7 | Icmp out echos | 8 | +| 8 | Icmp out timestamps | 9 | +| 9 | Icmp out timestamp reps | 10 | +| 10 | Icmp out addr masks | 11 | +| 11 | Icmp out addr mask reps | 12 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.4.10 ARP service profile + +This managed entity organizes data associated with the ARP function used by an IP router. The OLT creates or deletes an instance of this managed entity upon the creation or deletion of the corresponding instance of IP port configuration data of native LAN type. + +#### Relationships + +An instance of this managed entity is associated with one instance of IP port configuration data of native LAN type. The actual content of a port's ARP cache is visible through the implicitly linked ARP configuration data ME. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the slot id (defined in clause 9.1.5). It is 0 if the ONT is integrated. The second byte is assigned by the OLT in the range 1..255. (R, Set-by-create) (mandatory) (2 bytes) + +**ARP timer:** This attribute reports the maximum number of seconds that IP packets are held while they are awaiting address resolution by ARP at this port. (R) (mandatory) (4 bytes) + +**ARP cache clear:** The Boolean value true initializes the associated ARP cache. The value false has no significance. As the value of this attribute has no physical meaning, the get action always returns the value false. (R, W) (mandatory) (1 byte) + +#### Actions + +##### Create, delete, get, set + +#### Notifications + +None. + +### 9.4.11 ARP configuration data + +This managed entity organizes data associated with the ARP function related to an IP router. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of an associated ARP service profile. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the ARP service profile. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the ARP service profile. (R) (mandatory) (2 bytes) +- ARP table max size:** This attribute defines the maximum number of ARP entries that can be stored in the ARP table. Its value is determined by the ONT implementation. (R) (mandatory) (2 bytes) +- ARP table:** This attribute lists the current entries in the ARP cache. An ARP cache entry contains several fields: +- | | | +|---------------------|--------------------------------------------------------------------| +| port: | The port number of the IP port associated with the entry. (1 byte) | +| IP address: | An IP address. (4 bytes) | +| MAC address: | An equivalent MAC address resolved by the ARP procedure. (6 bytes) | +| type: | The entry type such as dynamic (3) or static (4). (1 byte) | +- (R) (mandatory) (12N bytes, where N is the number of entries) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### 9.4.12 IP host config data + +The IP host config data configures IP-based services offered on the ONT. The ONT automatically creates instances of this managed entity if IP host services are available. + +#### *Relationships* + +An instance of this managed entity is associated with the ONT managed entity. Any number of TCP/UDP MEs can point to the IP host config data, to model any number of ports and protocols. Performance may be monitored through an implicitly linked IP host PM history data ME. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The ONT creates as many instances as there are independent IP stacks on the ONT. (R) (mandatory) (2 bytes) + +| | | +|-------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| IP options: |

This attribute is a bit map that enables or disables IP-related options. The value 1 enables the option while 0 disables it.

0x1            Enable DHCP.
0x2            Respond to pings.
0x4            Respond to traceroute messages.
0x8..0x80   Reserved.

(R, W) (mandatory) (1 byte)

| +| MAC address: | This attribute indicates the MAC address used by the IP node. (R) (mandatory) (6 bytes) | +| Ont identifier: | A unique ONT identifier string. If set to a non-null value, this string is used instead of the MAC address in retrieving DHCP parameters. If the string is shorter than 25 characters, it must be null terminated. Its default value is 25 null bytes. (R, W) (mandatory) (25 bytes) | +| IP address: | The address used for IP host services, this attribute has default value 0 (not set). If this value is set, it overrides any values returned in DHCP. (R, W) (mandatory) (4 bytes) | +| Mask: | The subnet mask for IP host services, this attribute has default value 0 (not set). If this value is set, it overrides any values returned in DHCP. (R, W) (mandatory) (4 bytes) | +| Gateway: | The default gateway address used for IP host services, this attribute has default value 0 (not set). If this value is set, it overrides any values returned in DHCP. (R, W) (mandatory) (4 bytes) | +| Primary DNS: | The address of the primary DNS server, this attribute has default value 0 (not set). If this value is set, it overrides any values returned in DHCP. (R, W) (mandatory) (4 bytes) | +| Secondary DNS: | The address of the secondary DNS server, this attribute has default value 0 (not set). If this value is set, it overrides any values returned in DHCP. (R, W) (mandatory) (4 bytes) | +| Current address: | Current address of the IP host service. The ONT updates this attribute if DHCP assigns a new address. (R) (optional) (4 bytes) | +| Current mask: | Current subnet mask for the IP host service. The ONT updates this attribute if DHCP assigns a new mask. (R) (optional) (4 bytes) | +| Current gateway: | Current default gateway address for the IP host service. The ONT updates this attribute if DHCP assigns a new gateway. (R) (optional) (4 bytes) | +| Current primary DNS: | Current primary DNS server address. The ONT updates this attribute if DHCP assigns a new address. (R) (optional) (4 bytes) | +| Current secondary DNS: | Current secondary DNS server address. The ONT updates this attribute if DHCP assigns a new address. (R) (optional) (4 bytes) | +| Domain name: | If DHCP indicates a domain name, it is presented here. If no domain name is indicated, this attribute is set to a null string. If the string is shorter than 25 bytes, it must be null terminated. The default value is 25 null bytes. (R) (mandatory) (25 bytes) | + +**Host name:** If DHCP indicates a host name, it is presented here. If no host name is indicated, this attribute is set to a null string. If the string is shorter than 25 bytes, it must be null terminated. The default value is 25 null bytes. (R) (mandatory) (25 bytes) + +#### *Actions* + +#### **Get, set** + +**Test:** Invoke an ICMP message from this IP host. The test message can be configured to generate a ping or traceroute. Appendix II defines the test, test response and test result messages. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------| +| 1..8 | N/A | | +| 9 | Current address | The new value assigned via DHCP | +| 10 | Current mask | The new value assigned via DHCP | +| 11 | Current gateway | The new value assigned via DHCP | +| 12 | Current primary DNS | The new value assigned via DHCP | +| 13 | Current secondary DNS | The new value assigned via DHCP | +| 14 | Domain name | The new value assigned via DHCP | +| 15 | Host name | The new value assigned via DHCP | +| 16 | Reserved | | + +### **9.4.13 IP host performance monitoring history data** + +This managed entity collects performance monitoring data related to an IP host. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the IP host managed entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP host configuration data ME. (R, Set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) + +**ICMP errors:** This attribute counts ICMP errors received. (R) (mandatory) (4 bytes) + +**DNS errors:** This attribute counts DNS errors received. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|---------------|---------------------------------|-------------------------------------------| +| 0 | N/A | | +| 1 | IPNPM ICMP error | 1 | +| 2 | IPNPM DNS error | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.4.14 TCP/UDP config data** + +The TCP/UDP config data managed entity contains the configuration for TCP- and UDP-based services that are offered from an IP host. If a non-OMCI interface is used to manage an IP service, this ME is unnecessary. The non-OMCI interface supplies the necessary data. + +An instance of this managed entity is created and deleted on request of the OLT. + +#### *Relationships* + +One or more instances of this managed entity may be associated with an instance of an IP host config data managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. It is recommended that the managed entity id be the same as the port number. (R, Set-by-create) (mandatory) (2 bytes) +- Port id:** This attribute specifies the port number that offers the TCP/UDP service. (R, W, Set-by-create) (mandatory) (2 bytes) +- Protocol:** This attribute specifies the protocol type as defined by IANA. The default value is UDP (0x11) (R, W, Set-by-create) (mandatory) (1 byte) +- TOS/diffserv field:** This attribute specifies the value of the TOS/diffserv field of the IPv4 header. The contents of this attribute may contain the type of service per [IETF RFC 1349] or a differentiated services code point (DSCP). Valid values for DSCP are as defined by IANA. The default value is 0. (R, W, Set-by-create) (mandatory) (1 byte) +- IP host pointer:** This attribute points to the IP host config data ME associated with this TCP/UDP data. Any number of ports and protocols may be associated with an IP host. (R, W, Set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +## 9.5 Ethernet services + +This clause defines managed entities associated with physical Ethernet UNIs, as shown in Figure 9.5-1. + +![Diagram of managed entities associated with physical Ethernet UNIs](633486b12958f97e062b5cf9e0801e99_img.jpg) + +The diagram illustrates the central managed entity '9.5.1: PTPP Ethernet UNI'. To its left, 'Implicit links:' include 'Extended VLAN tagging operation config data'. Below it, 'Pointed to by:' lists '802.1p mapper service profile', 'IP port config data', 'MAC bridge port config data', and 'VLAN tagging operation config data'. To the right, three history data entities are shown: '9.5.2: Ethernet PM history data', '9.5.3: Ethernet PM history data 2', and '9.5.4: Ethernet PM history data 3', each with an arrow pointing towards the central UNI entity. + +Diagram of managed entities associated with physical Ethernet UNIs + +Figure 9.5-1 – Managed entities associated with physical Ethernet UNIs + +### 9.5.1 Physical path termination point Ethernet UNI + +This managed entity represents the point at an Ethernet UNI where the physical path terminates and Ethernet physical level functions are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has Ethernet ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of Ethernet type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of Ethernet type. Note that the installation of a plug-and-play card may indicate the presence of Ethernet ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies Ethernet ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect an Ethernet circuit pack, nor is it equipped with an Ethernet circuit pack. + +#### *Relationships* + +An instance of this managed entity is associated with each instance of a preprovisioned or real Ethernet port. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Expected type:** This attribute supports pre-provisioning. It is coded as follows: + +| | | +|----------|----------------------------------------------------------------------------------------| +| 0 | Autosense. | +| 1 to 254 | One of the values from Table 9.1.5-1 that is compatible with an Ethernet circuit pack. | + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +##### **Sensed type:** + +When a circuit pack is present, this attribute represents its type as one of the values from Table 9.1.5-1. If the value of expected type is not 0, then the value of sensed type should be the same as the value of expected type. Upon ME instantiation, the ONT sets this attribute to 0. See also the note in the notifications below. + +(R) (mandatory if the ONT supports circuit packs with configurable interface types, e.g., 10/100 BaseT card) (1 byte) + +##### **Auto detection configuration:** + +This attribute sets the Ethernet port configuration: + +| Codepoint | Rate | Duplex | +|-----------|-----------|------------------| +| 0x00 | Auto | Auto | +| 0x01 | 10 only | Full duplex only | +| 0x02 | 100 only | Full duplex only | +| 0x03 | 1000 only | Full duplex only | +| 0x04 | Auto | Full duplex only | +| 0x10 | 10 only | Auto | +| 0x11 | 10 only | Half duplex only | +| 0x12 | 100 only | Half duplex only | +| 0x13 | 1000 only | Half duplex only | +| 0x14 | Auto | Half duplex only | +| 0x20 | 1000 only | Auto | +| 0x30 | 100 only | Auto | + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory for interfaces with auto detection options) (1 byte) + +##### **Ethernet loopback configuration:** + +This attribute sets the Ethernet loopback configuration: + +0 No loopback. + +3 Loop 3, loopback of downstream traffic after PHY transceiver. Loop 3 is depicted in Figure 9.5.1-5. + +Note that normal bridge behaviour may defeat the loopback signal, unless broadcast MAC addresses are used. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +![Diagram of Ethernet loopback configuration. An ONT (Optical Network Terminal) box contains a 'PHY transceiver'. An 'Ethernet UNI' (User Network Interface) is connected to the left side of the PHY transceiver. A 'PON' (Passive Optical Network) interface is connected to the right side. A loopback arrow labeled 'Loopback 3' originates from the output of the PHY transceiver and loops back to its input, indicating that downstream traffic is looped back after the PHY transceiver.](17e0c0ae0c4cb562e192cbde7642a209_img.jpg) + +Diagram of Ethernet loopback configuration. An ONT (Optical Network Terminal) box contains a 'PHY transceiver'. An 'Ethernet UNI' (User Network Interface) is connected to the left side of the PHY transceiver. A 'PON' (Passive Optical Network) interface is connected to the right side. A loopback arrow labeled 'Loopback 3' originates from the output of the PHY transceiver and loops back to its input, indicating that downstream traffic is looped back after the PHY transceiver. + +**Figure 9.5.1-1 – Ethernet loopback configuration** + +| | | +|------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Administrative state: | This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) | +| Operational state: | This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) | +| Configuration ind: |

This attribute indicates the configuration status of the Ethernet UNI.

0x01 10BaseT full duplex.
0x02 100BaseT full duplex.
0x03 Gigabit Ethernet full duplex.
0x11 10BaseT half duplex.
0x12 100BaseT half duplex.
0x13 Gigabit Ethernet half duplex.

The value 0 indicates that the configuration status is unknown (e.g., Ethernet link is not established or the circuit pack is not yet installed). Upon ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (1 byte)

| +| Max frame size: | This attribute denotes the maximum frame size allowed across this interface. Upon ME instantiation, the ONT sets the attribute to 1518. (R, W) (mandatory) (2 bytes) | +| DTE or DCE ind: |

This attribute specifies the Ethernet interface wiring:

0 DCE (default).
1 DTE.

(R, W) (mandatory) (1 byte)

| +| Pause time: | This attribute allows the PPTP to ask the subscriber terminal to temporarily suspend sending data. Units are in pause quanta (1 pause quantum is 512 bit times of the particular implementation). Values: 0..0xFFFF. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (2 bytes) | +| Bridged or IP ind: |

This attribute specifies whether the Ethernet interface is bridged or derived from an IP router function

0 Bridged.
1 IP router.
2 Depends on the parent circuit pack. 2 means that the circuit pack's bridged or IP ind attribute is either 0 or 1.

Upon ME instantiation, the ONT sets this attribute to 2. (R, W) (optional) (1 byte)

| +| ARC: | See clause I.1.8. (R, W) (optional) (1 byte) | +| ARC interval: | See clause I.1.8. (R, W) (optional) (1 byte) | +| PPPoE filter: | This attribute controls filtering of PPPoE packets on this Ethernet port. The value 0 allows packets of all types. The value 1 discards everything but PPPoE packets. The default value is 0. (R, W) (optional) (1 byte) | + +**Power control:** This attribute controls whether power is provided to an external equipment over the Ethernet PPTP. The value 1 enables power over the Ethernet port. The default value 0 disables power feed. (R, W) (optional) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------------------------------------------------------------------------------------| +| 1 | N/A | | +| 2 | Sensed type | Sensed type of Ethernet interface. Valid values are 1 (10BaseT), 2 (100BaseT) and 3 (Gigabit Ethernet) (Note). | +| 3..5 | N/A | | +| 6 | Op state | Operational state | +| 7..11 | N/A | | +| 12 | ARC | ARC timer expiration | +| 13..15 | N/A | | +| 16 | Reserved | | + +NOTE – These values violate the rules of the AVC message, which require the changed value of the sensed type (in this case) attribute to be reported. Because of existing implementations, pre-existing documentation is retained; however, implementers should regard this attribute and its AVC with caution. + +##### **Alarm** + +| Number | Alarm | Description | +|----------|------------------------|--------------------------------| +| 0 | LAN-LOS | No carrier at the Ethernet UNI | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.5.2 Ethernet performance monitoring history data** + +This managed entity collects some of the performance monitoring data for an Ethernet interface. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the physical path termination point Ethernet UNI. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point Ethernet UNI. (R, Set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) + +| | | +|---------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| FCS errors: | This attribute counts frames received on a particular interface that were an integral number of octets in length but failed the frame check sequence (FCS) check. The count is incremented when the MAC service returns the frameCheckError status to the link layer control (LLC) or other MAC user. Received frames for which multiple error conditions are obtained are counted according to the error status presented to the LLC. (R) (mandatory) (4 bytes) | +| Excessive collision counter: | This attribute counts frames whose transmission failed due to excessive collisions. (R) (mandatory) (4 bytes) | +| Late collision counter: | This attribute counts the number of times that a collision was detected later than 512 bit times into the transmission of a packet. (R) (mandatory) (4 bytes) | +| Frames too long: | This attribute counts received frames that exceeded the maximum permitted frame size. The count is incremented when the MAC service returns the frameTooLong status to the LLC. (R) (mandatory) (4 bytes) | +| Buffer overflows on receive: | This attribute counts the number of times that the receive buffer overflowed. (R) (mandatory) (4 bytes) | +| Buffer overflows on transmit: | This attribute counts the number of times that the transmit buffer overflowed. (R) (mandatory) (4 bytes) | +| Single collision frame counter: | This attribute counts successfully transmitted frames whose transmission was delayed by exactly one collision. (R) (mandatory) (4 bytes) | +| Multiple collisions frame counter: | This attribute counts successfully transmitted frames whose transmission was delayed by more than one collision. (R) (mandatory) (4 bytes) | +| SQE counter: | This attribute counts the number of times that the SQE test error message was generated by the PLS sublayer. (R) (mandatory) (4 bytes) | +| Deferred transmission counter: | This attribute counts frames whose first transmission attempt was delayed because the medium was busy. The count does not include frames involved in collisions. (R) (mandatory) (4 bytes) | +| Internal MAC transmit error counter: | This attribute counts frames whose transmission failed due to an internal MAC sublayer transmit error. (R) (mandatory) (4 bytes) | +| Carrier sense error counter: | This attribute counts the number of times that carrier sense was lost or never asserted when attempting to transmit a frame. (R) (mandatory) (4 bytes) | +| Alignment error counter: | This attribute counts received frames that were not an integral number of octets in length and did not pass the FCS check. (R) (mandatory) (4 bytes) | +| Internal MAC receive error counter: | This attribute counts frames whose reception failed due to an internal MAC sublayer receive error. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|-------------------------------------|------------------------------------| +| 0 | FCS errors | 1 | +| 1 | Excessive collision counter | 2 | +| 2 | Late collision counter | 3 | +| 3 | Frames too long | 4 | +| 4 | Buffer overflows on receive | 5 | +| 5 | Buffer overflows on transmit | 6 | +| 6 | Single collision frame counter | 7 | +| 7 | Multiple collisions frame counter | 8 | +| 8 | SQE counter | 9 | +| 9 | Deferred transmission counter | 10 | +| 10 | Internal MAC transmit error counter | 11 | +| 11 | Carrier sense error counter | 12 | +| 12 | Alignment error counter | 13 | +| 13 | Internal MAC receive error counter | 14 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.5.3 Ethernet performance monitoring history data 2 + +This managed entity collects additional performance monitoring data for an Ethernet interface. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this Ethernet performance monitoring history data 2 managed entity is associated with an instance of the physical path termination point Ethernet UNI. + +#### Attributes + +| | | +|--------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point Ethernet UNI. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| PPPoE filtered frame counter: | This attribute counts the number of frames discarded due to PPPoE filtering. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|---------------|---------------------------------|-------------------------------------------| +| 0 | PPPoE filtered frame counter | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.5.4 Ethernet performance monitoring history data 3** + +This managed entity collects performance monitoring data associated with an Ethernet interface. It includes parameters defined in the Ethernet statistics group of [b-IETF RFC 2819] that are not already covered by previously defined Ethernet monitoring MEs. The received direction is from the CPE toward the network (upstream). + +Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the physical path termination point Ethernet UNI. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the PPTP Ethernet UNI. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Drop events:** The total number of events in which packets were dropped due to lack of resources. This is not necessarily the number of packets dropped; it is the number of times this event was detected. (R) (mandatory) (4 bytes) +- Octets:** The total number of octets received from the CPE, including those in bad packets, excluding framing bits, but including FCS. (R) (mandatory) (4 bytes) +- Packets:** The total number of packets received, including bad packets, broadcast packets and multicast packets. (R) (mandatory) (4 bytes) +- Broadcast packets:** The total number of received good packets directed to the broadcast address. This does not include multicast packets. (R) (mandatory) (4 bytes) + +| | | +|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Multicast packets: | The total number of received good packets directed to a multicast address. This does not include broadcast packets. (R) (mandatory) (4 bytes) | +| Undersize packets: | The total number of packets received that were less than 64 octets long but were otherwise well formed (excluding framing bits, but including FCS octets). (R) (mandatory) (4 bytes) | +| Fragments: | The total number of packets received that were less than 64 octets long, excluding framing bits but including FCS octets, and had either a bad frame check sequence (FCS) with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). It is entirely normal for this attribute to increment. This is because it counts both runs (which are normal occurrences due to collisions) and noise hits. (R) (mandatory) (4 bytes) | +| Jabbers: | The total number of packets received that were longer than 1518 octets, excluding framing bits but including FCS octets, and had either a bad frame check sequence (FCS) with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). The range to detect jabber is between 20 ms and 150 ms. (R) (mandatory) (4 bytes) | +| Packets 64 octets: | The total number of received packets (including bad packets) that were 64 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) | +| Packets 65 to 127 octets: | The total number of received packets (including bad packets) that were 65..127 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) | +| Packets 128 to 255 octets: | The total number of packets (including bad packets) received that were 128..255 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) | +| Packets 256 to 511 octets: | The total number of packets (including bad packets) received that were 256..511 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) | +| Packets 512 to 1023 octets: | The total number of packets (including bad packets) received that were 512..1023 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) | +| Packets 1024 to 1518 octets: | The total number of packets (including bad packets) received that were 1024..1518 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold data counter # (Note) | +|--------|--------------------------|---------------------------------| +| 0 | Drop events | 1 | +| 1 | Undersize packets | 2 | +| 2 | Fragments | 3 | +| 3 | Jabbers | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## 9.6 802.11 services + +This clause defines managed entities associated with physical [IEEE 802.11] UNIs, as shown in Figure 9.6-1. + +![Diagram showing managed entities associated with physical IEEE 802.11 UNI. The central entity is 9.6.1: PTP 802.11 UNI. It is linked to several other entities: 9.6.2: 802.11 station management data 1, 9.6.3: 802.11 station management data 2, 9.6.5: 802.11 MAC & PHY op and antenna data, 9.6.6: 802.11 PHY FHSS DSSS IR tables, 9.6.7: 802.11 PM history data, and 9.6.4: 802.11 general purpose object. The link to 9.6.4 is labeled 2..4. On the left, 'Implicit links' include Extended VLAN tagging operation config data. 'Pointed to by' include 802.1p mapper service profile, IP port config data, MAC bridge port config data, and VLAN tagging operation config data.](1d311a4e3c61cebfc0c034768e583899_img.jpg) + +``` + +graph TD + UNI[9.6.1: PTP 802.11 UNI] + UNI -- "Implicit links: +Extended VLAN tagging +operation config data" --> UNI + UNI -- "Pointed to by: +802.1p mapper service profile +IP port config data +MAC bridge port config data +VLAN tagging operation config data" --> UNI + UNI -- "2..4" --> GPO[9.6.4: 802.11 +general purpose +object] + UNI -.-> SM1[9.6.2: 802.11 station +management +data 1] + UNI -.-> SM2[9.6.3: 802.11 station +management +data 2] + UNI -.-> MAC[9.6.5: 802.11 MAC +& PHY op and +antenna data] + UNI -.-> PHY[9.6.6: 802.11 PHY +FHSS DSSS IR +tables] + UNI -.-> PM[9.6.7: 802.11 PM +history data] + +``` + +Diagram showing managed entities associated with physical IEEE 802.11 UNI. The central entity is 9.6.1: PTP 802.11 UNI. It is linked to several other entities: 9.6.2: 802.11 station management data 1, 9.6.3: 802.11 station management data 2, 9.6.5: 802.11 MAC & PHY op and antenna data, 9.6.6: 802.11 PHY FHSS DSSS IR tables, 9.6.7: 802.11 PM history data, and 9.6.4: 802.11 general purpose object. The link to 9.6.4 is labeled 2..4. On the left, 'Implicit links' include Extended VLAN tagging operation config data. 'Pointed to by' include 802.1p mapper service profile, IP port config data, MAC bridge port config data, and VLAN tagging operation config data. + +Figure 9.6-1 – Managed entities associated with physical IEEE 802.11 UNI + +All 802.11 UNIs supported by an ONT are implicitly grouped together into an implied diversity group. The model makes no provision to create more than one diversity group on a single ONT. + +### 9.6.1 Physical path termination point 802.11 UNI + +This managed entity models an 802.11 UNI, where physical paths terminate and physical path level functions are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has 802.11 ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of 802.11 type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of 802.11 type. Note that the installation of a plug-and-play card may indicate the presence of 802.11 ports via equipment ID as well as type, and indeed may cause the ONT to instantiate a port mapping package that specifies 802.11 ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect an 802.11 circuit pack, nor is it equipped with an 802.11 circuit pack. + +#### *Relationships* + +An instance of this managed entity is associated with each instance of an [IEEE 802.11] interface. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). If the UNI is integrated, this value is 0. The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**dot11 supported data rates tx:** This attribute specifies the set of data rates (maximum 8) at which the station is capable of transmitting data. Each octet contains a value representing a rate. Each rate lies within the range 2..127, corresponding to data rates in increments of 500 kbit/s from 1 Mbit/s to 63.5 Mbit/s. If fewer than 8 data rates are specified, each of the unused bytes is set to 0. (R) (mandatory) (8 bytes) + +**dot11 supported data rates rx:** This attribute specifies the set of data rates (maximum 8) at which the station is capable of receiving data. Each octet contains a value representing a rate. Each rate lies within the range 2..127, corresponding to data rates in increments of 500 kbit/s from 1 Mbit/s to 63.5 Mbit/s. If fewer than 8 data rates are specified, each of the unused bytes is set to 0. (R) (mandatory) (8 bytes) + +**dot11 Tx power levels:** This attribute specifies the set of transmit power levels (maximum 8) that the station is capable of using. Each 16-bit word contains a power setting, in units of mW. If fewer than 8 power levels are specified, each of the unused words is set to 0. (R) (mandatory) (16 bytes) + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state change | +| 3..5 | N/A | | +| 6 | ARC | ARC timer expiration | +| 7 | N/A | | +| 8..16 | Reserved | | + +### 9.6.2 802.11 station management data 1 + +This managed entity organizes some of the data associated with an 802.11 station. The ONT automatically creates or deletes an instance of this entity when it creates or deletes a PPTP 802.11 UNI instance. + +#### Relationships + +An instance of this managed entity is associated with one instance of an [IEEE 802.11] interface. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point 802.11 UNI. (R) (mandatory) (2 bytes) +- dot11 medium occupancy limit:** This attribute specifies the maximum amount of time, in TU, that a point coordinator may control the use of the wireless medium without relinquishing control for long enough to allow at least one instance of DCF access to the medium. The default value of this attribute is 100 TU; the maximum value is 1000. (R, W) (mandatory) (2 bytes) +- dot11 CF pollable:** The Boolean value true indicates that the STA is able to respond to a CF-poll with a data frame within one SIFS time. The attribute is false if the STA is not able to respond to a CF-Poll with a data frame within one SIFS time. (R) (mandatory) (1 byte) +- dot11 CFP period:** The attribute specifies the number of DTIM intervals between the start of CFPs. (R, W) (mandatory) (1 byte) +- dot11 CFP max duration:** The attribute specifies the maximum duration of the CFP in TU that may be generated by the PCF. (R, W) (mandatory) (2 bytes) +- dot11 authentication response timeout:** This attribute specifies the number of TU that a responding STA should wait for the next frame in the authentication sequence. (R, W) (mandatory) (4 bytes) +- dot11 privacy option implemented:** When true, this Boolean attribute indicates that the [IEEE 802.11] WEP option is implemented. The default value of this attribute is false. (R) (mandatory) (1 byte) +- dot11 power management mode:** This attribute specifies the power management mode of the STA. When active (0), the station is not in power save mode. Power save mode is specified by 1. (R, W) (mandatory) (1 byte) + +- dot11 desired SSID1:** This attribute contains the first half of the service set ID used in the desired SSID parameter of the most recent MLME\_Scan request. This value may be modified by an external management entity and used by the local SME to make decisions about the scanning process. (R, W) (mandatory) (16 bytes) +- dot11 desired SSID2:** This attribute contains the second half of the service set ID used in the desired SSID parameter of the most recent MLME\_Scan request. (R, W) (mandatory) (16 bytes) +- dot11 desired BSS type:** This attribute specifies the type of BSS the station accepts when scanning for a BSS with which to synchronize. The station filters probe response frames and beacons on the basis of this attribute. +- 0 Infrastructure: The station only synchronizes with a BSS whose capability information field has the ESS subfield set to 1. + - 1 Independent: The station only synchronizes with a BSS whose capability information field has the IBSS subfield set to 1. + - 2 Any: The station may synchronize to either type of BSS. +- (R, W) (mandatory) (1 byte) +- dot11 operational rate set:** This attribute specifies the set of data rates (maximum 8) at which the station may transmit data. Each octet contains a value representing a rate. Each rate lies within the range 2..127, corresponding to data rates in increments of 500 kbit/s from 1 Mbit/s to 63.5 Mbit/s. If fewer than 8 data rates are specified, each of the unused bytes is set to 0. This value is reported in transmitted beacon, probe request, probe response, association request, association response, reassociation request and reassociation response frames, and is used to determine whether a BSS with which the station desires to synchronize is suitable. (R, W) (mandatory) (8 bytes) +- dot11 beacon period:** This attribute specifies the number of TU that a station uses for scheduling beacon transmissions. This value is transmitted in beacon and probe response frames. (R, W) (mandatory) (2 bytes) +- dot11 DTIM period:** This attribute specifies the number of beacon intervals that elapse between transmission of beacon frames containing a TIM element whose DTIM count field is 0. This value is transmitted in the DTIM period field of beacon frames. (R, W) (mandatory) (1 byte) +- dot11 association response timeout:** This attribute specifies the number of TU that a requesting STA should wait for a response to a transmitted association-request MMPDU. (R, W) (mandatory) (4 bytes) +- dot11 authentication algorithm:** This attribute indicates all of the authentication algorithms supported by the STAs. The attribute is a bit map, formatted as follows: +- 0000 0000 0000 0000 0000 0000 0000 00yx, where: +- 0 Reserved + - x Open system + - 0 Not supported + - 1 Supported + - y Shared key + - 0 Not supported + - 1 Supported +- (R) (mandatory) (4 bytes) + +**dot11 authentication algorithms enable:** This attribute enables or disables the authentication algorithms supported by the STAs. The attribute is a bit map, formatted as follows: + +0000 0000 0000 0000 0000 0000 0000 00yx, where + +- 0 reserved +- x Open system + - 0 Not enabled + - 1 Enabled +- y Shared key + - 0 Not enabled + - 1 Enabled + +(R, W) (mandatory) (4 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.6.3 802.11 station management data 2** + +This managed entity organizes some of the data associated with an 802.11 station. The ONT automatically creates an instance of this entity whenever it creates a PPTP 802.11 UNI instance. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of an [IEEE 802.11] interface. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point 802.11 UNI. (R) (mandatory) (2 bytes) + +**dot11 disassociate reason:** This attribute records the reason code in the most recently transmitted disassociation frame. If no disassociation frame has been transmitted, the value of this attribute is 0. (R) (mandatory) (2 bytes) + +**dot11 disassociate station:** This attribute records the MAC address from the address 1 field of the most recently transmitted disassociation frame. If no disassociation frame has been transmitted, the value of this attribute is 0. (R) (mandatory) (6 bytes) + +**dot11 deauthenticate reason:** This attribute records the reason code in the most recently transmitted deauthentication frame. If no deauthentication frame has been transmitted, the value of this attribute is 0. (R) (mandatory) (2 bytes) + +**dot11 deauthenticate station:** This attribute records the MAC address from the address 1 field of the most recently transmitted deauthentication frame. If no deauthentication frame has been transmitted, the value of this attribute is 0. (R) (mandatory) (6 bytes) + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| dot11 authenticate fail status: | This attribute records the status code in the most recently transmitted failed authentication frame. If no failed authentication frame has been transmitted, the value of this attribute is 0. (R) (mandatory) (2 bytes) | +| dot11 authenticate fail station: | This attribute records the MAC address from the address 1 field of the most recently transmitted failed authentication frame. If no failed authentication frame has been transmitted, the value of this attribute is 0. (R) (mandatory) (6 bytes) | +| The four following attributes contain WEP default keys 1..4, respectively. For security, WEP default secret keys are write-only. The default value of each WEP default key is 0. | | +| dot11 WEP default key value1: | (W) (mandatory) (5 bytes) | +| dot11 WEP default key value2: | (W) (mandatory) (5 bytes) | +| dot11 WEP default key value3: | (W) (mandatory) (5 bytes) | +| dot11 WEP default key value4: | (W) (mandatory) (5 bytes) | +| dot11 privacy invoked and dot11 exclude unencrypted: | This attribute specifies two truth values. It is coded 0b0000 00yx, where x indicates the dot11 privacy invoked value, and y indicates the dot11 exclude unencrypted value.

When dot11 privacy invoked is true, [IEEE 802.11] WEP is used for transmitting data frames. The default value of this attribute is false.

When dot11 exclude unencrypted is true, the STA does not indicate received MSDUs whose WEP subfield of the frame control field is 0 at the MAC service interface. When this value is false, the STA may accept MSDUs whose WEP subfield of the frame control field is 0. The default value of this attribute is false.

(R, W) (mandatory) (1 byte) | +| dot11 WEP default key ID: | When set to values of 0..3, this attribute specifies use of WEP default key 1..4, respectively. The default value is 0. (R, W) (mandatory) (1 byte) | +| dot11 WEP key mapping length: | The maximum number of tuples that dot11 WEP key mappings can hold. Dot11 WEP key mappings are contained in the 802.11 general purpose object ME, object type 0. (R, W) (mandatory) (4 bytes) | +| dot11 WEP ICV error count: | This counter increments when a frame is received whose frame control field, WEP subfield, is 1, and whose received ICV does not match the ICV value calculated for the frame's contents. (R) (mandatory) (4 bytes) | +| dot11 WEP excluded count: | This counter increments when a frame is received whose WEP subfield of the frame control field is 0, and the value of dot11 exclude unencrypted causes that frame to be discarded. (R) (mandatory) (4 bytes) | + +#### Actions + +#### Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|---------------------------------|---------------------------------------------------------------------------------------------------| +| 1 | N/A | | +| 2 | dot11 disassociate station | MAC address from the address 1 field of the most recently transmitted disassociation frame | +| 3 | N/A | | +| 4 | dot11 deauthenticate station | MAC address from the address 1 field of the most recently transmitted deauthentication frame | +| 5 | N/A | | +| 6 | dot11 authenticate fail station | MAC address from the address 1 field of the most recently transmitted failed authentication frame | +| 7..12 | N/A | | +| 13..16 | Reserved | | + +### 9.6.4 802.11 general purpose object + +#### Relationships + +Up to four instances of this managed entity may exist for each instance of an [IEEE 802.11] interface, one of each type. An instance contains one of the following [IEEE 802.11] data types: WEP key mappings, group addresses, supported regulatory domains, and antennas list. Each use has its own attributes, and a type attribute indicates which subset is active for each instance. Regardless of which attributes are active, each attribute is numbered, in the OMCC attribute mask, according to the ordering of the full attribute set indicated below. + +For object types 0 and 1, the OLT may create and delete instances of this object. For object types 2 and 3, the ONT creates as many instances as required to model the UNI's capabilities. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. When created automatically by the ONT, the ME ID is known to the OLT through out of band means, for example documentation. (R, Set-by-create) (mandatory) (2 bytes) + +**Object type:** This attribute indicates how this entity is used: + +- 0 WEP key mapping. +- 1 Group addresses. +- 2 Reg domain supported. +- 3 Antennas list. + +For any given type, only the relevant attributes are valid. The other attributes are unspecified. (R, Set-by-create) (mandatory) (1 byte) + +**Physical path termination point 802.11 pointer:** This attribute points to the specific physical path termination point 802.11 UNI to which this instance corresponds. (R, Set-by create) (mandatory) (2 bytes) + +*Attributes valid only if object type = 0, WEP key mapping:* + +**dot11 WEP key mapping address:** The MAC address of the STA for which the values from this key mapping entry are to be used. (R, W, Set-by-create) (mandatory) (6 bytes) + +**dot11 WEP key mapping WEP on:** Boolean; true specifies that WEP is to be used when communicating with the dot11 WEP key mapping address STA. (R, W, Set-by-create) (mandatory) (1 byte) + +**dot11 WEP key mapping value:** A WEP secret key value. (W, Set-by-create) (mandatory) (5 bytes) + +*Attributes valid only if object type = 1, group addresses:* + +**dot11 address:** A multicast MAC address from which this STA receives frames. (R, W, Set-by-create) (mandatory) (6 bytes) + +*Attributes valid only if object type = 2, reg domain supported:* + +**dot11 reg domains support value:** Operational requirements differ, depending on the regulatory domain. This attribute list describes the regulatory domains that the PLCP and PMD support in this implementation. Currently defined values and their corresponding regulatory domains are: + +0x10 FCC (USA). +0x20 DOC (Canada). +0x30 ETSI (most of Europe). +0x31 Spain. +0x32 France. +0x40 MKK (Japan). +(R) (mandatory) (1 byte) + +*Attributes valid only if object type = 3, antennas list:* + +**dot11 supported tx antenna:** When true, this Boolean attribute indicates that the antenna represented by the associated PPTP can be used as a transmit antenna. (R) (mandatory) (1 byte) + +**dot11 supported rx antenna:** When true, this Boolean attribute indicates that the antenna represented by the associated PPTP can be used as a receive antenna. (R) (mandatory) (1 byte) + +**dot11 diversity selection rx:** When true, this Boolean attribute indicates that the antenna represented by the associated PPTP can be used for receive diversity. This attribute can only be true if the antenna can be used as a receive antenna, as indicated by dot11 supported rx antenna. (R, W) (mandatory) (1 byte) + +*Actions* + +**Create, delete, get, set** + +*Notifications* + +None. + +### 9.6.5 802.11 MAC and PHY operation and antenna data + +The ONT automatically creates an instance of this entity whenever it creates an instance of PPTP 802.11 UNI. + +*Relationships* + +An instance of this managed entity exists for each [IEEE 802.11] interface. + +#### *Attributes* + +| | | +|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point 802.11 UNI. (R) (mandatory) (2 bytes) | +| dot11 MAC address: | Unique MAC address assigned to the STA. (R) (mandatory) (6 bytes) | +| dot11 RTS threshold: | This attribute specifies the number of octets in an MPDU, at or below which no RTS/CTS handshake is performed. An RTS/CTS handshake is performed at the beginning of any frame exchange sequence where the PDU is of type data or management, the MPDU has an individual address in the address1 field, and the length of the MPDU is greater than this threshold. Setting this attribute to be larger than the maximum MSDU size has the effect of turning off the RTS/CTS handshake for all data and management frames transmitted by this STA. Setting this attribute to 0 has the effect of turning on the RTS/CTS handshake for all data and management frames transmitted by this STA. The default value of this attribute is 2347. (R, W) (mandatory) (2 bytes) | +| dot11 short retry limit: | This attribute specifies the maximum number of transmission attempts of a frame whose length is less than or equal to dot11 RTS threshold, before a failure condition is indicated. The default value of this attribute is 7. (R, W) (mandatory) (1 byte) | +| dot11 long retry limit: | This attribute specifies the maximum number of transmission attempts of a frame whose length is greater than dot11 RTS threshold, before a failure condition is indicated. The default value of this attribute is 4. (R, W) (mandatory) (1 byte) | +| dot11 fragmentation threshold: | This attribute specifies the maximum size, in octets, of the MPDU that may be delivered to the PHY. An MSDU is broken into fragments if its size exceeds the value of this attribute after adding MAC headers and trailers. An MSDU or MMPDU is fragmented when the resulting frame has an individual address in the address1 field, and the length of the frame is larger than this threshold. The default value for this attribute is the lesser of 2346 or the aMPDU max length of the attached PHY. The attribute value may never be set to exceed this limit, and may never be less than 256. (R, W) (mandatory) (2 bytes) | +| dot11 max transmit MSDU lifetime: | The max transmit MSDU lifetime is the elapsed time in TU, from the initial transmission of an MSDU until further attempts to transmit it are terminated. The default value of this attribute is 512. (R, W) (mandatory) (4 bytes) | +| dot11 max receive lifetime: | The max receive lifetime is the elapsed time in TU, from the initial reception of a fragmented MMPDU or MSDU until further attempts to reassemble the MMPDU or MSDU are terminated. The default value is 512. (R, W) (mandatory) (4 bytes) | + +| | | +|------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| dot11 PHY type: |

This attribute identifies the PHY type supported by the attached PLCP and PMD. Currently defined values and their corresponding PHY types are:

  1. 1 FHSS 2.4 GHz.
  2. 2 DSSS 2.4 GHz.
  3. 3 IR baseband.

(R) (mandatory) (1 byte)

| +| dot11 current reg domain: |

The current regulatory domain this instance of the PMD is supporting. This object corresponds to one of the reg domains listed in dot11 reg domains supported value attribute of the PPTP's 802.11 general purpose object of type 2. (R, W) (mandatory) (4 bytes)

| +| dot11 temp type: |

There are different operating temperature requirements according to anticipated environmental conditions. This attribute describes the current PHY's operating temperature range capability. Currently defined values and their corresponding temperature ranges are:

  1. 1 Type 1 – Commercial range, 0 to 40 degrees C.
  2. 2 Type 2 – Industrial range, –30 to 70 degrees C.

(R) (mandatory) (1 byte)

| +| dot11 current tx antenna pointer: |

This pointer attribute specifies the transmit antenna to be used. The attribute is only permitted to point to an 802.11 PPTP whose 802.11 general purpose object, object type 3, dot11 supported tx antenna attribute is true. The value 0 is a null pointer. (R, W) (mandatory) (2 bytes)

| +| dot11 diversity support: |

This attribute indicates the ONT's support for diversity, encoded as:

  1. 1 Diversity is available and is performed over the fixed list of antennas defined by the dot11 diversity selection rx attribute values of the set of general purpose object ME instances of object type = 3.
  2. 2 Diversity is not supported.
  3. 3 Diversity is supported and control of diversity is also available, in which case the corresponding 802.11 general purpose object, object type 3, dot11 diversity selection rx attribute can be dynamically modified by the LME.

(R) (mandatory) (1 byte)

| +| dot11 current rx antenna pointer: |

This pointer attribute specifies the receive antenna if the corresponding 802.11 general purpose object, object type 3, dot11 diversity support indicates that diversity is not supported. The attribute is only permitted to point to an 802.11 PPTP whose 802.11 general purpose object, object type 3, dot11 supported rx antenna attribute is true. The value 0 is a null pointer. (R, W) (mandatory) (2 bytes)

| + +**dot11 current tx power level:** The power level currently being used to transmit data. Some PHYs also use this value to determine the receiver sensitivity requirements for CCA. Valid values range from 0 to 7 and indicate which word in the dot11 tx power levels attribute of the physical path termination point 802.11 UNI object is the current power level (which PPTP 802.11 UNI is determined by the dot11 current tx antenna pointer attribute). (R, W) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.6.6 802.11 PHY FHSS DSSS IR tables** + +#### *Relationships* + +One instance of this managed entity may exist for each instance of an [IEEE 802.11] interface. The ONT automatically creates an instance of this entity whenever it creates an instance of the PPTP 802.11 UNI. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point 802.11 UNI. (R) (mandatory) (2 bytes) + +**dot11 hop time:** This attribute reports the time in microseconds for the PMD to change from channel 2 to channel 80. (R) (mandatory) (1 byte) + +**dot11 current channel number:** This attribute provisions the channel number of the RF synthesizer. (R, W) (mandatory) (1 byte) + +**dot11 max dwell time:** This attribute reports the maximum time in TU that the transmitter operates on a single channel. (R) (mandatory) (2 bytes) + +**dot11 current dwell time:** This attribute provisions the time in TU that the transmitter may operate on a single channel. The default is 19 TU. (R, W) (mandatory) (2 bytes) + +**dot11 current set:** This attribute provisions the set of patterns to be used by the PHY LME to determine the hop sequence. (R, W) (mandatory) (1 byte) + +**dot11 current pattern:** This attribute provisions the pattern to be used by the PHY LME to determine the hop sequence. (R, W) (mandatory) (1 byte) + +**dot11 current index:** This attribute provisions the index value to be used by the PHY LME to determine the current channel number. (R, W) (mandatory) (1 byte) + +**dot11 current channel:** This attribute provisions the operating frequency channel to be used by the DSSS PHY. Valid channel numbers are defined in clause 15.4.6.2 of [IEEE 802.11]. (R, W) (mandatory) (1 byte) + +**dot11 CCA mode supported:** A bit map representing the CCA modes supported by the PHY. Valid values are: + +0x01 Energy detect only (ED only). +0x02 Carrier sense only (CS only). +0x04 Carrier sense and energy detect (ED and CS). + +or the sum of any of these values. (R) (mandatory) (1 byte) + +**dot11 current CCA mode:** This attribute provisions the CCA method to be used by the PHY. Valid values are: + +0x01 Energy detect only (ED only). +0x02 Carrier sense only (CS only). +0x04 Carrier sense and energy detect (ED and CS). + +(R, W) (mandatory) (1 byte) + +**dot11 ED threshold:** This attribute provisions the energy detect threshold to be used by the DSSS PHY. (R, W) (mandatory) (4 bytes) + +Together, the following two attributes specify when energy detected in the channel can be ignored. Units are in time ticks. + +**dot11 CCA watchdog timer max:** (R, W) (mandatory) (4 bytes) + +**dot11 CCA watchdog count max:** (R, W) (mandatory) (4 bytes) + +**dot11 CCA watchdog timer min:** This attribute provisions the minimum value to which the dot11 CCA watchdog timer max can be set. Units are time ticks. (R, W) (mandatory) (4 bytes) + +**dot11 CCA watchdog count min:** This attribute provisions the minimum value to which the dot11 CCA watchdog count can be set. Units are time ticks. (R, W) (mandatory) (4 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.6.7 802.11 performance monitoring history data** + +This managed entity collects performance monitoring data for an instance of an 802.11 physical path termination point. Instances of this managed entity are created and deleted by the OLT. + +NOTE – This managed entity was formerly known by the name 802.11 counters. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of an [IEEE 802.11] interface. + +#### *Attributes* + +| | | +|-------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point 802.11 UNI. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| dot11 transmitted fragment count: | This attribute counts acknowledged MPDUs with an individual address in the address 1 field and MPDUs of type data or management with a multicast address in the address 1 field. (R) (mandatory) (4 bytes) | +| dot11 multicast transmitted frame count: | This attribute counts successfully transmitted MSDUs with the multicast bit set in the destination MAC address. When operating as a STA in an ESS, where these frames are directed to the AP, this implies having received an acknowledgment to all associated MPDUs. (R) (mandatory) (4 bytes) | +| dot11 failed count: | This attribute counts MSDUs that were not transmitted successfully because the number of transmit attempts exceeded either the dot11 short retry limit or dot11 long retry limit, as specified in the corresponding attributes of the associated 802.11 MAC and PHY operation and antenna data managed entity. (R) (mandatory) (4 bytes) | +| dot11 retry count: | This attribute counts MSDUs transmitted successfully after one or more retransmissions. (R) (mandatory) (4 bytes) | +| dot11 multiple retry count: | This attribute counts MSDUs transmitted successfully after more than one retransmission. (R) (mandatory) (4 bytes) | +| dot11 frame duplicate count: | This attribute counts duplicate received frames according to their sequence control fields. (R) (mandatory) (4 bytes) | +| dot11 RTS success count: | This attribute counts CTSs received in response to RTSs. (R) (mandatory) (4 bytes) | +| dot11 RTS failure count: | This attribute counts failures to receive CTS in response to an RTS. (R) (mandatory) (4 bytes) | +| dot11 ACK failure count: | This attribute counts failures to receive ACK when expected. (R) (mandatory) (4 bytes) | +| dot11 received fragment count: | This attribute counts successfully received MPDUs of type data or management. (R) (mandatory) (4 bytes) | +| dot11 multicast received frame count: | This attribute counts received MSDUs whose multicast bit is set in the destination MAC address. (R) (mandatory) (4 bytes) | +| dot11 FCS error count: | This attribute counts FCS errors detected in received MPDUs. (R) (mandatory) (4 bytes) | + +**dot11 transmitted frame count:** This attribute counts successfully transmitted MSDUs. (R) (mandatory) (4 bytes) + +**dot11 WEP undecryptable count:** This attribute counts frames received whose frame control field, WEP subfield, is 1, when the WEPOn value for the key mapped to the TA's MAC address indicates that the frame should not have been encrypted. It also counts frames discarded because the receiving STA did not implement the privacy option. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | dot11 failed | 1 | +| 1 | dot11 RTS failure | 2 | +| 2 | dot11 ACK failure | 3 | +| 3 | dot11 FCS error | 4 | +| 4 | dot11 WEP undecryptable | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## 9.7 xDSL services + +This clause defines managed entities associated with physical xDSL UNIs, as shown in Figure 9.7-1. + +![Figure 9.7-1: Managed entities associated with physical xDSL UNIs. This is a relationship diagram showing various managed entities and their associations with the central entity '9.7.1: PTP xDSL UNI part 1' and '9.7.2: Part 2'. Entities are represented in rectangular boxes, and associations are shown with arrows, some labeled 'N' for many-to-one relationships. On the left, entities include line config profiles (9.7.3-9.7.6), PSD mask profile (9.7.10), downstream RFI bands profile (9.7.11), and subcarrier masking downstream profile (9.7.8). These point to the central UNI entity. The central UNI entity points to line inventory and status data (9.7.12-9.7.18), channel config profile (9.7.7), and subcarrier masking upstream profile (9.7.9). On the right, status and history data entities (9.7.19-9.7.25) are associated with the UNI entity via 'd' (downstream) and 'u' (upstream) labels. A list of 'Implicit links' and 'Pointed to by' relationships is provided at the top left.](bae60391325927710f2cb0599f4ce1d5_img.jpg) + +**Implicit links:** +Extended VLAN tagging operation config data + +**Pointed to by:** +802.1p mapper service profile +VP network CTP-G +IP port config data +MAC bridge port config data +VLAN tagging operation config data + +**Managed Entities:** + +- 9.7.1: PTP xDSL UNI part 1 +9.7.2: Part 2 +- 9.7.3: xDSL line config profile 1 +9.7.4: Part 2 +9.7.5: Part 3 +9.7.6: VDSL2 line config extensions +- 9.7.10: xDSL PSD mask profile +- 9.7.11: xDSL downstream RFI bands profile +- 9.7.8: xDSL subcarrier masking downstream profile +- 9.7.12: xDSL line inventory and status data 1 +9.7.13: Part 2 +9.7.14: Part 3 +9.7.15: Part 4 +9.7.16: VDSL2 line inventory and status data 1 +9.7.17: Part 2 +9.7.18: Part 3 +- 9.7.7: xDSL channel config profile +- 9.7.9: xDSL subcarrier masking upstream profile +- 9.7.19: xDSL channel downstream status data +- 9.7.20: xDSL channel upstream status data +- 9.7.21: xDSL xTU-C PM history data +- 9.7.22: xDSL xTU-R PM history data +- 9.7.23: xDSL xTU-C channel PM history data +- 9.7.24: xDSL xTU-R channel PM history data +- 9.7.25: TC adaptor PM history data + +Figure 9.7-1: Managed entities associated with physical xDSL UNIs. This is a relationship diagram showing various managed entities and their associations with the central entity '9.7.1: PTP xDSL UNI part 1' and '9.7.2: Part 2'. Entities are represented in rectangular boxes, and associations are shown with arrows, some labeled 'N' for many-to-one relationships. On the left, entities include line config profiles (9.7.3-9.7.6), PSD mask profile (9.7.10), downstream RFI bands profile (9.7.11), and subcarrier masking downstream profile (9.7.8). These point to the central UNI entity. The central UNI entity points to line inventory and status data (9.7.12-9.7.18), channel config profile (9.7.7), and subcarrier masking upstream profile (9.7.9). On the right, status and history data entities (9.7.19-9.7.25) are associated with the UNI entity via 'd' (downstream) and 'u' (upstream) labels. A list of 'Implicit links' and 'Pointed to by' relationships is provided at the top left. + +Figure 9.7-1 – Managed entities associated with physical xDSL UNIs + +### 9.7.1 Physical path termination point xDSL UNI part 1 + +This managed entity represents the point where physical paths terminate on an xDSL CO modem (xTU-C). The xDSL managed entity family is used for ADSL and VDSL2 services (an existing legacy family of VDSL managed entities remains valid for [ITU-T G.993.1] VDSL. It is documented in [ITU-T G.983.2]). + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has xDSL ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of xDSL type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of xDSL type. Note that the installation of a plug-and-play card may indicate the presence of xDSL ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies xDSL ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect an xDSL circuit pack, nor is it equipped with an xDSL circuit pack. + +#### Relationships + +An instance of this managed entity is associated with each instance of a real or preprovisioned xDSL port. + +#### Attributes + +| | | +|----------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The six least significant bits of the first byte are the slot id, defined in clause 9.1.5. The two most significant bits indicate the channel number in some of the implicitly linked MEs, and must be 0 in the PPTP itself. This reduces the possible number of physical slots to 64. The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) | +| Loopback configuration: | This attribute represents the loopback configuration of this physical interface.
0 No loopback.
1 Loopback2 – A loopback at the ONT toward the OLT. The OLT can execute a physical level loopback test after loopback2 is set.
Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) | +| Administrative state: | This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) | +| Operational state: | This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) | +| xDSL line configuration profile: | This attribute points to an instance of the xDSL line configuration profiles (part 1, 2 and 3) managed entities, and if [ITU-T G.993.2] VDSL2 is supported, also to a VDSL2 line configuration extensions ME. Upon ME instantiation, the ONT sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) | +| xDSL subcarrier masking downstream profile: | This attribute points to an instance of the xDSL subcarrier masking downstream profile managed entity. Upon ME instantiation, the ONT sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) | +| xDSL subcarrier masking upstream profile: | This attribute points to an instance of the xDSL subcarrier masking upstream profile managed entity. Upon ME instantiation, the ONT sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) | +| xDSL downstream PSD mask profile: | This attribute points to an instance of the xDSL PSD mask profile managed entity that defines downstream parameters. Upon ME instantiation, the ONT sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) | +| xDSL downstream RFI bands profile: | This attribute points to an instance of the xDSL downstream RFI bands profile managed entity. Upon ME instantiation, the ONT sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) | + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +**Modem type:** This attribute specifies the modem type. If the hardware cannot support the requested modem type, the ONT should deny the provisioning command. For backward compatibility, the attribute is optional, with a default of ATM. + +0 Undefined. + 1 ATM (default). + 2 PTM (Ethernet). + +(R, W) (optional) (1 byte) + +**Upstream PSD mask profile:** This attribute points to an instance of the xDSL PSD mask profile that defines upstream parameters. Upon ME instantiation, the ONT sets this attribute to 0, a null pointer. (R, W) (optional) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------| +| 1..2 | N/A | | +| 3 | Op state | Operational state | +| 4..8 | N/A | | +| 9 | ARC | ARC timer expiration | +| 10..13 | N/A | | +| 14..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|--------|----------|---------------------------------------------| +| 0 | NE LOF | Near end loss of frame | +| 1 | NE LOS | Near end loss of signal | +| 2 | NE LOL | Near end loss of link | +| 3 | NE LPR | Near end loss of power | +| 4 | Card alm | Card in alarm | +| 5 | FE LOF | Far end loss of frame | +| 6 | FE LOS | Far end loss of signal | +| 7 | FE LOL | Far end loss of link | +| 8 | FE LPR | Far end loss of power | +| 9 | DRT up | Data rate threshold upshift (Note 1) | +| 10 | DRT down | Data rate threshold downshift (Note 1) | +| 11 | LINIT | Line initialization failure | +| 12 | LCD | Loss of cell delineation, near end (Note 2) | +| 13 | NCD | No cell delineation, near end (Note 2) | + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|--------------------------------------------| +| 14 | LCD-FE | Loss of cell delineation, far end (Note 2) | +| 15 | NCD-FE | No cell delineation, far end (Note 2) | +| 16..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +NOTE 1 – The data rate upshift and downshift notifications are triggered by individual bearer channels. The alarms may be declared against the UNI itself, or against one of the bearer channels. In the latter case, the two MSBs of the instance identifier in the alarm message specify the bearer channel. + +NOTE 2 – These alarms are meaningful only for ATM transport. The alarms may be declared against the UNI itself, or against one of the bearer channels. In the latter case, the two MSBs of the instance identifier in the alarm message specify the bearer channel. + +### 9.7.2 Physical path termination point xDSL UNI part 2 + +This managed entity represents the point in the ONT where physical paths terminate on an xDSL CO modem (xTU-C). Standards and chip sets support several forms of DSL, including VDSL2, and the xDSL managed entity family is used for all of them, with specific extensions for technology variations (a legacy family of managed entities is documented in [ITU-T G.983.2] for [ITU-T G.993.1] VDSL1). + +The ONT creates or deletes an instance of this managed entity at the same time it creates or deletes the corresponding PPTP xDSL UNI part 1. + +#### Relationships + +An instance of this managed entity is associated with each instance of a physical path termination point xDSL UNI part 1. + +#### Attributes + +| | | +|----------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL UNI part 1. (R) (mandatory) (2 bytes) | +| | Each of the following eight attributes is a pointer to an xDSL channel configuration profile managed entity. In each case, the default value 0, set when the ME is auto-created, is a null pointer. | +| xDSL channel configuration profile for bearer channel 0 downstream: | (R, W) (optional) (2 bytes) | +| xDSL channel configuration profile for bearer channel 1 downstream: | (R, W) (optional) (2 bytes) | +| xDSL channel configuration profile for bearer channel 2 downstream: | (R, W) (optional) (2 bytes) | +| xDSL channel configuration profile for bearer channel 3 downstream: | (R, W) (optional) (2 bytes) | +| xDSL channel configuration profile for bearer channel 0 upstream: | (R, W) (optional) (2 bytes) | + +**xDSL channel configuration profile** (R, W) (optional) (2 bytes) +**for bearer channel 1 upstream:** + +**xDSL channel configuration profile** (R, W) (optional) (2 bytes) +**for bearer channel 2 upstream:** + +**xDSL channel configuration profile** (R, W) (optional) (2 bytes) +**for bearer channel 3 upstream:** + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.7.3 xDSL line configuration profile part 1** + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common managed entity id (the client physical path termination point xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration profile parts). + +Be aware that a number of attributes in the line configuration profile family affect the real-time service delivery of an xDSL UNI, for example by triggering diagnostics. Despite the fact that they are called profiles, it may be advisable to instantiate a complete set of these MEs for each PPTP xDSL UNI. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. All xDSL and VDSL2 line configuration profiles that pertain to a given physical path termination point xDSL must share a common managed entity id. (R, Set-by-create) (mandatory) (2 bytes) + +**xTU transmission system enabling (xTSE):** This configuration attribute specifies the transmission system coding types to be allowed by the near-end xTU. It is a bit map as defined in Table 9.7.12-1. + +NOTE 1 – An additional byte enabling VDSL2 capabilities is defined in the VDSL2 transmission system enabling attribute of the xDSL line configuration profile part 2 managed entity. + +(R, W, Set-by-create) (mandatory) (7 bytes) + +| | | +|-----------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Power management state forced: |

This configuration parameter forces the line state of the near-end xTU. It is coded as an integer value with following definition:

  • 0 Force the line from the L3 idle state to the L0 full-on state. This transition requires the short initialization procedures. After reaching the L0 state, the line may enter into or exit from the L2 low power state if the L2 state is enabled. If the L0 state is not reached after a vendor-discretionary number of retries and/or within a vendor-discretionary timeout, an initialization failure occurs. Whenever the line is in the L3 state, it attempts to transition to the L0 state until it is forced into another state through this configuration parameter.
  • 2 Force the line from the L0 full-on to L2 low power state. This is an out-of-service test value for triggering the L2 mode.
  • 3 Force the line from the L0 full-on or L2 low power state to the L3 idle state. This transition requires the orderly shutdown procedure. After reaching the L3 state, the line remains there until it is forced into another state through this configuration parameter.

(R, W, Set-by-create) (mandatory) (1 byte)

| +| Power management state enabling: |

This configuration parameter specifies the line states into which the xTU-C or xTU-R may autonomously go. It is a bit map (0 if not allowed, 1 if allowed) with the following definition:

Bit 1 (LSB): L3 idle state.
Bit 2: L1/L2 low power state.

(R, W, Set-by-create) (mandatory) (1 byte)

| +| Downstream target noise margin: |

This attribute specifies the noise margin the xTU-R receiver must achieve, relative to the BER requirement for each of the downstream bearer channels, to successfully complete initialization. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (mandatory) (2 bytes)

| +| Upstream target noise margin: |

This attribute specifies the noise margin the xTU-C receiver must achieve, relative to the BER requirement for each of the upstream bearer channels, to successfully complete initialization. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (mandatory) (2 bytes)

| +| Downstream maximum noise margin: |

This attribute specifies the maximum noise margin the xTU-R receiver tries to sustain. If the noise margin is above this level, the xTU-R requests the xTU-C to reduce its transmit power, if this functionality is supported. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). The special value 0xFFFF indicates that the maximum noise margin limit is unbounded. (R, W, Set-by-create) (mandatory) (2 bytes)

| + +| | | +|-----------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Upstream maximum noise margin: | This attribute specifies the maximum noise margin the xTU-C receiver tries to sustain. If the noise margin is above this level, the xTU-C requests the xTU-R to reduce its transmit power, if this functionality is supported. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). The special value 0xFFFF indicates that the maximum noise margin limit is unbounded. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Downstream minimum noise margin: | This attribute specifies the minimum noise margin the xTU-R receiver must tolerate. If the noise margin falls below this level, the xTU-R requests the xTU-C to increase its transmit power. If an increase in xTU-C transmit power is not possible, a loss-of-margin (LOM) defect occurs, the xTU-R fails and attempts to re-initialize, and the PPTP declares a line initialization failure (LINIT) alarm. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (mandatory) (2 bytes) | +| Upstream minimum noise margin: | This attribute specifies the minimum noise margin the xTU-C receiver must tolerate. If the noise margin falls below this level, the xTU-C requests the xTU-R to increase its transmit power. If an increase in xTU-R transmit power is not possible, a loss-of-margin (LOM) defect occurs, the xTU-C fails and attempts to re-initialize, and the PPTP declares a line initialization failure (LINIT) alarm. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (mandatory) (2 bytes) | +| Downstream rate adaptation mode: | This attribute specifies the mode of operation of a rate-adaptive xTU-C in the transmit direction. The parameter can take three values. | + +##### **1 Mode 1: MANUAL** – Rate changed manually. + +*At startup:* + +The downstream minimum data rate parameter (see xDSL channel config profile) specifies the minimum required data rate for each downstream bearer channel, with a downstream noise margin that is at least as large as the specified downstream target noise margin, relative to the required BER for each of the downstream bearer channels. If the xTU-C fails to achieve the downstream minimum data rate for any of the bearer channels, the xTU-C fails to initialize and the PPTP declares a line initialization failure (LINIT) alarm. Although the xTU-C and the line might be able to support a higher data rate, the xTU-C does not transmit a higher data rate than is requested. + +*At showtime:* + +The xTU-C transmitter maintains the specified downstream minimum data rate for each of the bearer channels. + +##### **2 Mode 2: AT\_INIT** – Rate automatically selected at startup only; rate does not change after that. + +*At startup:* + +The downstream minimum rate parameter specifies the minimum required data rate for each downstream bearer channel, with a downstream noise margin that is at least as large as the specified downstream target noise margin, relative to the required BER for each of the bearer channels. If the xTU-C fails to achieve the downstream minimum data rate for any of the bearer channels, the xTU-C fails to initialize and the PPTP declares a line initialization failure (LINIT) alarm. If the xTU-C transmitter is able to support a higher downstream data rate at initialization, the excess data rate is distributed among the downstream bearer channels according to the weight specified by the rate adaptation ratio parameter of each bearer channel. When the downstream maximum data rate is achieved in one of the bearer channels, the remaining excess rate is assigned to the other bearer channels, still according to their relative rate adaptation ratio parameters. As long as the downstream data rate is below the downstream maximum data rate for one of the bearer channels, data rate increase takes priority over transmit power reduction. + +*At showtime:* + +During showtime, no downstream data rate adaptation is allowed. The downstream data rate, determined during initialization for each bearer channel, is maintained. + +**3 Mode 3: DYNAMIC** – Data rate is automatically selected at initialization and is continuously adapted during showtime. The dynamic rate adaptation mode is optional. All related configuration parameters are also optional. + +*At startup:* + +The xTU-C starts up as in mode 2. + +*At showtime:* + +During showtime, rate adaptation is allowed according to the rate adaptation ratios for distributing the excess data rate amongst the bearer channels, as described in mode 2. The downstream data rate can vary between the downstream minimum data rate and the downstream maximum data rate. Downstream rate adaptation is performed when the conditions specified for downstream upshift noise margin and downstream upshift interval – or for downstream downshift noise margin and downstream downshift interval – are satisfied. This means: + +- An upshift action is allowed when the downstream noise margin is above the downstream upshift noise margin during the downstream minimum time interval for upshift rate adaptation (i.e., upon RAU anomaly). + +- A downshift action is allowed when the downstream noise margin is below the downstream downshift noise margin during the downstream minimum time interval for downshift rate adaptation (i.e., upon RAD anomaly). + +As long as the downstream data rate is below the downstream maximum data rate for one of the bearer channels, data rate increase takes priority over transmit power reduction. + +(R, W, Set-by-create) (mandatory) (1 byte) + +##### **Upstream rate adaptation mode:** + +This attribute specifies the mode of operation of a rate-adaptive xTU-R in the transmit direction. The parameter is used only if rate-adaptive functionality is supported. It can take three values: + +- 1 MANUAL. +- 2 AT\_INIT. +- 3 DYNAMIC. + +The definition of each of the values is identical to its definition in the downstream rate adaptation mode (replacing *xTU-C* with *xTU-R* and *downstream* with *upstream*). (R, W, Set-by-create) (mandatory) (1 byte) + +##### **Downstream upshift noise margin:** + +If the downstream noise margin is above the downstream upshift noise margin and remains there for more than the time specified by the downstream minimum upshift rate adaptation interval, the xTU-R attempts to increase the downstream net data rate. This attribute ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (optional) (2 bytes) + +##### **Upstream upshift noise margin:** + +If the upstream noise margin is above the upstream upshift noise margin and remains there for more than the time specified by the upstream minimum upshift rate adaptation interval, the xTU-C attempts to increase the upstream net data rate. This attribute ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (optional) (2 bytes) + +**Upstream PSD mask selection:** This attribute enables one of several upstream PSD masks. It is used only for Annexes J and M of [ITU-T G.992.3] and [ITU-T G.992.5]. The same mask selection applies to all relevant modes enabled in the xTSE line configuration parameter (Table 9.7.12-1). This attribute selects the mask with the following definition: + +###### **Annex J of G.992.3/5**    **Annex M of G.992.3/5** + +| | | | +|---|---------|-------| +| 1 | ADLU-32 | EU-32 | +| 2 | ADLU-36 | EU-36 | +| 3 | ADLU-40 | EU-40 | +| 4 | ADLU-44 | EU-44 | +| 5 | ADLU-48 | EU-48 | +| 6 | ADLU-52 | EU-52 | +| 7 | ADLU-56 | EU-56 | +| 8 | ADLU-60 | EU-60 | +| 9 | ADLU-64 | EU-64 | + +(R, W, Set-by-create) (mandatory) (1 byte) + +##### **Minimum overhead rate upstream:** + +This attribute specifies the minimum rate of the message based overhead to be maintained by the xTU in the upstream direction. MSGMINus ranges from 4000 to 248 000 bit/s. This attribute is only valid for [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. + +NOTE 2 – For compatibility with previous versions, values between 4000 and 65535 are interpreted as bits per second. To align with [ITU-T G.997.1], values between 4 and 248 are interpreted as kilobits per second. For maximum flexibility, the ONT should support both conventions. + +(R, W, Set-by-create) (optional) (2 bytes) + +##### **Minimum overhead rate downstream:** + +This attribute specifies the minimum rate of the message based overhead to be maintained by the xTU in the downstream direction. MSGMINds ranges from 4000 to 248 000 bit/s. This attribute is only valid for [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. + +NOTE 3 – For compatibility with previous versions, values between 4000 and 65535 are interpreted as bits per second. To align with [ITU-T G.997.1], values between 4 and 248 are interpreted as kilobits per second. For maximum flexibility, the ONT should support both conventions. + +(R, W, Set-by-create) (optional) (2 bytes) + +#### **Actions** + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.7.4 xDSL line configuration profile part 2** + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common managed entity id (the client physical path termination point xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration profile parts). + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI part 1. + +#### Attributes + +| | | +|------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. All xDSL and VDSL2 line configuration profiles that pertain to a given physical path termination point xDSL must share a common managed entity id. (R, Set-by-create) (mandatory) (2 bytes) | +| Downstream minimum time interval for upshift rate adaptation: | This parameter defines the interval during which the downstream noise margin must remain above the downstream upshift noise margin before the xTU-R attempts to increase the downstream net data rate. Its value ranges from 0 to 16383 seconds. (R, W, Set-by-create) (optional) (2 bytes) | +| Upstream minimum time interval for upshift rate adaptation: | This parameter defines the interval during which the upstream noise margin must remain above the upstream upshift noise margin before the xTU-C attempts to increase the upstream net data rate. Its value ranges from 0 to 16383 seconds. (R, W, Set-by-create) (optional) (2 bytes) | +| Downstream downshift noise margin: | If the downstream noise margin is below the downstream downshift noise margin and remains there for more than the downstream minimum downshift rate adaptation interval, the xTU-R attempts to decrease the downstream net data rate. This attribute's value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (optional) (2 bytes) | +| Upstream downshift noise margin: | If the upstream noise margin is below the upstream downshift noise margin and remains there for more than the upstream minimum downshift rate adaptation interval, the xTU-C attempts to decrease the upstream net data rate. This attribute's value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, Set-by-create) (optional) (2 bytes) | +| Downstream minimum time interval for downshift rate adaptation: | This parameter defines the interval during which the downstream noise margin must remain below the downstream downshift noise margin before the xTU-R attempts to decrease the downstream net data rate. Its value ranges from 0 to 16383 seconds. (R, W, Set-by-create) (optional) (2 bytes) | +| Upstream minimum time interval for downshift rate adaptation: | This parameter defines the interval during which the upstream noise margin must remain below the upstream downshift noise margin before the xTU-C attempts to decrease the upstream net data rate. Its value ranges from 0 to 16383 seconds. (R, W, Set-by-create) (optional) (2 bytes) | +| xTU impedance state forced: |

This parameter forces the impedance state of the xTU-C. It applies only to the T/S interface, and is deprecated in OMCI, which stands proxy for the Q interface. It is only valid for Annex A of [ITU-T G.992.3], Annex A of [ITU-T G.992.4] and Annex A of [ITU-T G.992.5]. It is defined as follows:

  1. 1 Force the xTU-C to the disabled state.
  2. 2 Force the xTU-C to the inactive state.
  3. 3 Force the xTU-C to the active state.

(R, W, Set-by-create) (optional) (1 byte)

| + +| | | +|-------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| L0-time: | This parameter specifies the minimum time between an exit from the L2 state and the next entry into the L2 state. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. It ranges from 0 to 255 seconds. (R, W, Set-by-create) (mandatory) (1 byte) | +| L2-time: | This parameter specifies the minimum time between an entry into the L2 state and the first power trim in the L2 state, or between two consecutive power trims in the L2 state. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. It ranges from 0 to 255 seconds. (R, W, Set-by-create) (mandatory) (1 byte) | +| Downstream maximum nominal power spectral density: | This attribute specifies the maximum nominal transmit PSD in the downstream direction during initialization and showtime. A single MAXNOMPSDds attribute is defined per mode enabled in the xTSE line configuration attribute. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. Its value ranges from 0 (-60.0 dBm/Hz) to 300 (-30 dBm/Hz). (R, W, Set-by-create) (mandatory) (2 bytes) | +| Upstream maximum nominal power spectral density: | This attribute specifies the maximum nominal transmit PSD in the upstream direction during initialization and showtime. A single MAXNOMPSDus attribute is defined per mode enabled in the xTSE line configuration attribute. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.993.2]. Its value ranges from 0 (-60.0 dBm/Hz) to 300 (-30 dBm/Hz). (R, W, Set-by-create) (mandatory) (2 bytes) | +| Downstream maximum nominal aggregate transmit power: | This attribute specifies the maximum nominal aggregate transmit power in the downstream direction during initialization and showtime. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. Its value ranges from 0 (0.0 dBm) to 255 (25.5 dBm). (R, W, Set-by-create) (mandatory) (1 byte) | +| Upstream maximum nominal aggregate transmit power: | This parameter specifies the maximum nominal aggregate transmit power in the upstream direction during initialization and showtime. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. Its value ranges from 0 (0.0 dBm) to 255 (25.5 dBm). (R, W, Set-by-create) (mandatory) (1 byte) | +| Upstream maximum aggregate receive power: | This parameter specifies the maximum upstream aggregate receive power over a set of subcarriers, as defined in the relevant Recommendation. The xTU-C requests an upstream power cutback such that the upstream aggregate receive power over that set of subcarriers is at or below the configured maximum value. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. This attribute ranges from 0 (-25.5 dBm) to 510 (+25.5 dBm). The special value 0xFFFF indicates that no upstream maximum aggregate receive power limit is to be applied. (R, W Set-by-create) (mandatory) (2 bytes) | +| VDSL2 transmission system enabling: | This configuration attribute extends the transmission system coding types to be allowed by the xTU-C. It is a bit map, defined as octet 8 (bits 57..64) in Table 9.7.12-1. (R, W, Set-by-create) (optional) (1 byte) | + +*Actions* + +**Create, delete, get, set** + +*Notifications* + +None. + +### 9.7.5 xDSL line configuration profile part 3 + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common managed entity id (the client physical path termination point xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration profile parts). + +*Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI part 1. + +*Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. All xDSL and VDSL2 line configuration profiles that pertain to a given physical path termination point xDSL must share a common managed entity id. (R, Set-by-create) (mandatory) (2 bytes) + +**Loop diagnostics mode forced (LDSF):** This configuration parameter forces the line into loop diagnostic mode via the xTU-C. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. It is defined as follows: + +- 0 Inhibits the xTU-C from performing loop diagnostic mode procedures on the line. Loop diagnostic mode procedures may still be initiated by the xTU-R. +- 1 Forces the xTU-C to perform the loop diagnostics procedures. + +Only while the line power management state is L3 can the line be forced into loop diagnostic mode. When loop diagnostic procedures complete successfully, the ONT resets this attribute to 0. The line remains in L3 idle state. The loop diagnostics data are available at least until the line is forced to the L0 state. As long as loop diagnostic procedures have not completed successfully, attempts are made to do so, until the loop diagnostic mode is no longer forced on the line through this configuration parameter. If loop diagnostic procedures cannot be completed successfully after a vendor-discretionary number of retries and/or within a vendor-discretionary timeout, then an initialization failure occurs. (R, W, Set-by-create) (mandatory) (1 byte) + +**Automode cold start forced:** This attribute is defined to improve testing of the performance of xTUs supporting automode. Valid values are 0 and 1. A change in value of this attribute indicates a change in loop conditions applied to the devices under test. The xTUs reset any historical information used for automode, for shortening G.994.1 handshake, or for shortening the initialization procedure. + +Automode is defined as the case where multiple operation modes are enabled in xTSE Table 9.7.12-1 and where the selection of the operation mode to be used for transmission depends, not only on the common capabilities of both xTUs (as exchanged in [ITU-T G.994.1]), but also on achievable data rates under given loop conditions. (R, W, Set-by-create) (mandatory if automode supported) (1 byte) + +**L2-ATPR:** This parameter specifies the maximum aggregate transmit power reduction that can be performed in the L2 request (i.e., at the transition of L0 to L2 state) or through a single power trim in the L2 state. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. This attribute ranges from 0 (0 dB) dB to 31 (31 dB). (R, W, Set-by-create) (mandatory) (1 byte) + +**L2-ATPRT:** This parameter specifies the total maximum aggregate transmit power reduction (in dB) that can be performed in an L2 state. This is the sum of all reductions of L2 requests (i.e., at transitions from L0 to L2 state) and power trims. This attribute ranges from 0 (0 dB) dB to 31 (31 dB). (R, W, Set-by-create) (mandatory) (1 byte) + +**Force INP downstream:** When set to 1, this attribute forces the framer settings of all downstream bearer channels to be selected such that the impulse noise protection computed according to the formula specified in the relevant Recommendation is greater than or equal to the minimal impulse noise protection requirement. The default value 0 disables this function. (R, W) (mandatory for [ITU-T G.993.2]) (1 byte) + +**Force INP upstream:** When set to 1, this attribute forces the framer settings of all upstream bearer channels to be selected such that the impulse noise protection computed according to the formula specified in the relevant Recommendation is greater than or equal to the minimal impulse noise protection requirement. The default value 0 disables this function. (R, W) (mandatory for [ITU-T G.993.2]) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.7.6 VDSL2 line configuration extensions** + +This managed entity extends the xDSL line configuration MEs with attributes that are unique to [ITU-T G.993.2] VDSL2. The attributes of this ME are further defined in [ITU-T G.997.1]. An instance of this managed entity is created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI part 1. + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common managed entity id (the client physical path termination point xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration parts). + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. All xDSL and VDSL2 line configuration profiles that pertain to a given physical path termination point xDSL must share a common managed entity id. (R, Set-by-create) (mandatory) (2 bytes) + +**VDSL2 profiles enabling:** This attribute (PROFILES) contains the G.993.2 profiles to be allowed by the xTU-C. It is coded in a bit map representation (0 if not allowed, 1 if allowed) with the following definition: + +| Bit | Meaning | +|-------------------|-----------------------| +| 1 (LSB) | G.993.2 profile 8a. | +| 2 | G.993.2 profile 8b. | +| 3 | G.993.2 profile 8c. | +| 4 | G.993.2 profile 8d. | +| 5 | G.993.2 profile 12a. | +| 6 | G.993.2 profile 12b. | +| 7 | G.993.2 profile 17a. | +| 8 | G.993.2 profile 30a. | + +(R, W, Set-by-create) (mandatory) (1 byte) + +**VDSL2 PSD mask class selection (CLASSMASK):** To reduce the number of configuration possibilities, the limit PSD masks are grouped in the following PSD mask classes: + +- Class 998 Annex A: D-32, D-48, D-64, D-128. +- Class 997-M1c Annex B: 997-M1c-A-7. +- Class 997-M1x Annex B: 997-M1x-M-8, 997-M1x-M. +- Class 997-M2x Annex B: 997-M2x-M-8, 997-M2x-A, 997-M2x-M, 997E17-M2x-NUS0, 997E30-M2x-NUS0. +- Class 998-M1x Annex B: 998-M1x-A, 998-M1x-B, 998-M1x-NUS0. +- Class 998-M2x Annex B: 998-M2x-A, 998-M2x-M, 998-M2x-B, 998-M2x-NUS0, 998E17-M2x-NUS0, 998E17-M2x-NUS0-M, 998E30-M2x-NUS0, 998E30-M2x-NUS0-M. +- Class 998ADE-M2x Annex B: 998-M2x-A, 998-M2x-M, 998-M2x-B, 998-M2x-NUS0, 998ADE17-M2x-A, 998ADE17-M2x-B, 998ADE17-M2x-NUS0-M, 998ADE30-M2x-NUS0-A, 998ADE30-M2x-NUS0-M. +- Class 998-B Annex C: POTS-138b, POTS-276b (clause C.2.1.1 of [ITU-T G.993.2]), TCM-ISDN (clause C.2.1.2 of [ITU-T G.993.2]). +- Class 998-CO Annex C: POTS-138co, POTS-276co (clause C.2.1.1 of [ITU-T G.993.2]). +- Class HPE-M1 Annex B: HPE17-M1-NUS0, HPE30-M1-NUS0. + +Each class is designed such that the PSD levels of each limit PSD mask of a specific class are equal in their respective passbands above 552 kHz. + +The CLASSMASK attribute is defined per annex enabled in the xTSE table (see Table 9.7.12-1). It selects a single PSD mask class per annex to be activated at the VTU-O. The coding is as follows: + +| Attribute value | G.993.2 Annex A | G.993.2 Annex B | G.993.2
Annex C | +|-------------------------------|-------------------------------|-------------------------------|------------------------------------------------| +| 1 | 998 | 997-M1c | 998-B | +| 2 | | 997-M1x | 998-CO | +| 3 | | 997-M2x | | +| 4 | | 998-M1x | | +| 5 | | 998-M2x | | +| 6 | | 998ADE-M2x | | +| 7 | | HPE | | + +NOTE 1 – A single PSD mask class may be selected per [ITU-T G.993.2] annex. (R, W, Set-by-create) (mandatory) (1 byte) + +##### **VDSL2 limit PSD masks:** + +The LIMITMASK attribute contains the G.993.2 limit PSD masks of the selected PSD mask class, enabled by the near-end xTU for each class of profiles. One LIMITMASK parameter is defined per annex enabled in the xTSE (see Table 9.7.12-1). + +The profiles are grouped in the following profile classes: + +- Class 8: Profiles 8a, 8b, 8c, 8d. +- Class 12: Profiles 12a, 12b. +- Class 17: Profile 17a. +- Class 30: Profile 30a. + +For each profile class, several limit PSD masks of the selected PSD mask class (CLASSMASK) may be enabled. The enabling attribute is coded in a bit map representation (0 if the associated mask is not allowed, 1 if it is allowed). The bit mask is defined in Table 9.7.6-1. (R, W, Set-by-create) (mandatory) (8 bytes) + +##### **VDSL2 US0 disabling:** + +The US0DISABLE attribute specifies whether channel US0 is disabled for each limit PSD mask enabled in the LIMITMASK attribute. + +For each limit PSD mask enabled in the LIMITMASK attribute, one bit indicates if US0 is disabled. The disabling attribute is a bit map where the value 1 specifies that US0 is disabled for the associated limit mask. The bit map has the same structure as the LIMITMASK attribute. (R, W, Set-by-create) (mandatory) (8 bytes) + +##### **VDSL2 US0 PSD masks:** + +The US0MASK attribute contains the US0 PSD masks to be allowed by the xTU-C. This attribute is only defined for Annex A of [ITU-T G.993.2]. It is represented as a bit map (0 if not allowed, 1 if allowed) with the definitions of Table 9.7.6-2. (R, W, Set-by-create) (mandatory) (4 bytes) + +##### **VDSL2-CARMASK table:** + +This attribute specifies restrictions, additional to the band plan, that determine the set of subcarriers allowed for transmission in both upstream and downstream directions. + +The VDSL2-CARMASK attribute describes the not-masked subcarriers in terms of one or more frequency bands. Each band is represented by start and stop subcarrier indices with a subcarrier spacing of 4.3125 kHz. The valid range of subcarrier indices is from 0 to at least the index of the highest allowed subcarrier in both transmission directions among all profiles enabled by the VDSL2 profiles enabling (PROFILES) attribute. Up to 32 bands may be specified. Other subcarriers are masked. + +For profiles using 8.625 kHz tone spacing, the odd subcarrier indices $i_{4.3125}$ in VDSL2-CARMASK can be transformed into actual subcarrier indices $i_{8.625}$ using the following rule: + +- For the start frequency of each band: $i_{8.625} = (i_{4.3125} + 1)/2$ . +- For the stop frequency of each band: $i_{8.625} = (i_{4.3125} - 1)/2$ . + +The VDSL2-CARMASK attribute is a table where each entry comprises: + +- An entry number field (1 byte, first entry numbered 1). +- Band start subcarrier index (2 bytes). +- Band stop subcarrier index (2 bytes). + +By default, the table is empty. Entries are added or modified using the set action, which permits from one to as many as six breakpoints to be addressed in a single set message (Note 2). Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier references to zero implies deletion from the table, if present. + +NOTE 2 – OMCI does not provide robust exception handling when more than one entry is included in a set command, and multiple values per set operation are not recommended. + +The maximum number of breakpoints is 32, so the maximum size of the table is 160 bytes. (R, W) (mandatory) (5N bytes, where N is the number of bands) + +##### **CARMASK valid:** + +This attribute controls and reports the status of the VDSL2-CARMASK table. If CARMASK valid = 1, then the VDSL2-CARMASK has been effectuated on the xDSL equipment. If CARMASK valid = 0 (default), then the VDSL2-CARMASK table is under construction and has not been effectuated on the xDSL equipment. + +This attribute behaves as follows: + +- If the OLT changes any of the VDSL2-CARMASK table entries or sets CARMASK valid = 0, then CARMASK valid = 0. +- If CARMASK valid = 0 and the OLT sets CARMASK valid = 1, then the ONT updates the xDSL equipment with the content of the table. + +(R, W) (mandatory) (1 byte) + +**UPBOSHAPED:** Upstream power back-off (UPBO) is specified in [ITU-T G.993.2] to provide spectral compatibility between loops of different lengths deployed in the same cable binder. The upstream transmit PSD mask, UPBOMASKus is defined in clause 7.2.1.3.2 of [ITU-T G.993.2] using the formula: + +$$UPBOMASK(kl_0, f) = UPBOPSD(f) + LOSS(kl_0, f) + 3.5 \text{ [dBm/Hz]}$$ + +$$LOSS(kl_0, f) = kl_0 \sqrt{f} \text{ [dB]}$$ + +where $UPBOPSD(f) = -a - b\sqrt{f}$ . + +The UPBO configuration attributes $a$ and $b$ are set by the OLT via this attribute. The value of $kl_0$ may be determined during initialization by the VTUs or also set by the OLT. Further detail appears in [ITU-T G.997.1]. + +This attribute includes two parameters for each band. The parameters are $a$ and $b$ , in that order. Parameter $a$ lies in the range 4000 (40.00 dBm/Hz) to 8095 (80.95 dBm/Hz). Parameter $b$ lies in the range 0 (0.00 dBm/Hz) to 4095 (40.95 dBm/Hz). The special values $a = b = 0$ disable UPBO in the respective upstream band. + +The upstream electrical length parameter UPBOKL defines the electrical length expressed in dB at 1 MHz, $kl_0$ , which may also be configured by the OLT. Its value ranges from 0 (0.0 dB) to 1280 (128.0 dB). + +If the force electrical length parameter UPBOKLF is 1, the VTU-R is forced to use the electrical length from this attribute (UPBOKL) to compute UPBO. Otherwise, the VTUs determine the electrical length themselves. + +| | | | +|-----------------|---|---------| +| Upstream band 1 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 2 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 3 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 4 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 5 | a | 2 bytes | +| | b | 2 bytes | +| UPBOKL | | 2 bytes | +| UPBOKLF | | 1 byte | + +(R, W) (mandatory) (23 bytes) + +**Cyclic extension:** The CEFLAG attribute enables (1) the optional cyclic extension values. If set to 0, the cyclic extension is forced to the mandatory length $5N/32$ . (R, W) (mandatory) (1 byte) + +**Downstream SNR mode:** The SNRMODEd attribute controls transmitter referred virtual noise in the downstream direction. If set to 1, virtual noise is disabled. If set to 2, virtual noise is enabled. (R, W) (mandatory) (1 byte) + +**Upstream SNR mode:** The SNRMODEus attribute controls transmitter referred virtual noise in the upstream direction. If set to 1, virtual noise is disabled. If set to 2, virtual noise is enabled. (R, W) (mandatory) (1 byte) + +**Transmitter referred virtual noise downstream table:** The TXREFVNds table defines the downstream transmitter referred virtual noise. TXREFVNds is specified through a set of breakpoints. Each breakpoint comprises a subcarrier index $t$ , with a subcarrier spacing of 4.3125 kHz, and a noise PSD level at that subcarrier. The set of breakpoints can then be represented as $[(t_1, \text{PSD}_1), (t_2, \text{PSD}_2), \dots, (t_N, \text{PSD}_N)]$ . The subcarrier index $t$ is an unsigned two-byte integer. The noise level is one byte whose value ranges from 0 (–40 dBm/Hz) to 200 (–140 dBm/Hz), in steps of 0.5 dB. Values between 201 and 254 indicate a noise PSD level of 0 W/Hz. The maximum number of breakpoints is 32. + +Table entries for this attribute have default value 254 for the noise PSD level. Entries are added or modified using the set action. Setting an entry to a noise PSD level less than or equal to 254 implies insertion into the table. Setting an entry's noise PSD level to 255 implies deletion from the table, if present. + +NOTE 3 – OMCI does not provide robust exception handling when more than one entry is included in a set command, and multiple values per set operation are not recommended. + +(R, W) (optional) (3N bytes, where N is the number of breakpoints) + +**Transmitter referred virtual noise upstream table:** The TXREFVNus attribute defines the upstream transmitter referred virtual noise. TXREFVNus is specified through a set of breakpoints. Each breakpoint comprises a subcarrier index $t$ , with a subcarrier spacing of 4.3125 kHz, and a noise PSD level at that subcarrier. The set of breakpoints can then be represented as $[(t_1, \text{PSD}_1), (t_2, \text{PSD}_2), \dots, (t_N, \text{PSD}_N)]$ . The subcarrier index $t$ is an unsigned two-byte integer. The noise level is one byte whose value ranges from 0 (–40 dBm/Hz) to 200 (–140 dBm/Hz), in steps of 0.5 dB. Values between 201 and 254 indicate a noise PSD level of 0 W/Hz. The maximum number of breakpoints is 16. + +Table entries for this attribute have default value 254 for the noise PSD level. Entries are added or modified using the set action. Setting an entry to a noise PSD level less than or equal to 254 implies insertion into the table. Setting an entry's noise PSD level to 255 implies deletion from the table, if present. + +NOTE 4 – OMCI does not provide robust exception handling when more than one entry is included in a set command, and multiple values per set operation are not recommended. + +(R, W) (optional) (3N bytes, where N is the number of breakpoints) + +**DPBOSHAPED:** Downstream power back-off – shaped as described in [ITU-T G.997.1] as a vector of parameters that modifies the downstream PSD mask. + +**DPBOEPSD** – Assumed exchange PSD mask. This component points to an xDSL downstream PSD mask profile managed entity. It should contain not more than 16 break points. (2 bytes) + +**DPBOESEL** – E-side electrical length. This component is the assumed loss at some reference frequency of the electrical cable from the xDSL equipment to a possible flexibility point. It ranges from 0 (0.0 dB) to 511 (255.5 dB) in steps of 0.5 dB. The value 0 has the special meaning that it disables the DPBOSHAPED feature. (2 bytes) + +The following three parameters describe the cable model. Further detail appears in [ITU-T G.997.1]. Each is a scalar that represents the range –1 (coded as 0) to +1.5 (coded as 640) in steps of 1/256. + +**DPBOESCMA** – (2 bytes) + +**DPBOESCMB** – (2 bytes) + +**DPBOESCMC** – (2 bytes) + +**DPBOMUS** – Assumed minimum usable receive PSD mask. This component ranges from 0 (0.0 dBm/Hz) to 255 (–127.5 dBm/Hz) in steps of 0.5 dB. (1 byte) + +**DPBOFMIN** – The lower frequency bound above which DPBO is applied. This component ranges from 0 (0.00 kHz) to 2048 (8832.00 kHz) in steps of 4.3125 kHz. (2 bytes) + +**DPBOFMAX** – The upper frequency bound below which DPBO is applied. This component ranges from 32 (138.00 kHz) to 6956 (29997.75 kHz) in steps of 4.3125 kHz. (2 bytes) + +(R, W) (optional) (15 bytes) + +#### *Actions* + +**Create, delete, get, get next, set** + +#### *Notifications* + +None. + +PSD mask classes: + +**Table 9.7.6-1 – Limit mask definitions for each class mask** + +| Bit | Annex A | Annex B | | | | | | | Annex C | | +|--------------------------|----------------|--------------------|--------------------|---------------------------|--------------------|--------------------|--------------------|-------------------|------------------|-------------------| +| | 998
Annex A | 998-M1x
Annex B | 998-M2x
Annex B | 998ADE-
M2x
Annex B | 997-M1x
Annex B | 997-M1c
Annex B | 997-M2x
Annex B | HPE-M1
Annex B | 998-B
Annex C | 998-CO
Annex C | +| Octet 1, profile class 8 | | | | | | | | | | | +| 1 | D-32 | M1x-A | M2x-A | M2x-A | | M1c-A-7 | M2x-A | | POTS-138b | POTS-138co | +| 2 | D-48 | M1x-B | M2x-B | M2x-B | M1x-M-8 | | M2x-M-8 | | TCM-ISDN | POTS-276co | +| 3 | | | M2x-M | M2x-M | M1x-M | | M2x-M | | POTS-276b | | +| 4 | | M1x-NUS0 | M2x-NUS0 | M2x-NUS0 | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | + +**Table 9.7.6-1 – Limit mask definitions for each class mask** + +| Bit | Annex A | Annex B | | | | | | | Annex C | | +|---------------------------|----------------|--------------------|--------------------|---------------------------|--------------------|--------------------|--------------------|-------------------|------------------|-------------------| +| | 998
Annex A | 998-M1x
Annex B | 998-M2x
Annex B | 998ADE-
M2x
Annex B | 997-M1x
Annex B | 997-M1c
Annex B | 997-M2x
Annex B | HPE-M1
Annex B | 998-B
Annex C | 998-CO
Annex C | +| Octet 2, profile class 8 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 3, profile class 12 | | | | | | | | | | | +| 1 | D-32 | M1x-A | M2x-A | M2x-A | | | M2x-A | | POTS-138b | POTS-138co | +| 2 | D-48 | M1x-B | M2x-B | M2x-B | | | | | TCM-ISDN | POTS-276co | +| 3 | | | M2x-M | M2x-M | M1x-M | | M2x-M | | POTS-276b | | +| 4 | | M1x-NUS0 | M2x-NUS0 | M2x-NUS0 | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 4, profile class 12 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 5, profile class 17 | | | | | | | | | | | +| 1 | D-32 | | E17-M2x-NUS0 | ADE17-M2x-A | | | E17-M2x-NUS0 | 17-M1-NUS0 | POTS-138b | | +| 2 | D-48 | | E17-M2x-NUS0-M | ADE17-M2x-B | | | | | TCM-ISDN | | +| 3 | | | | ADE17-M2x-NUS0-M | | | | | POTS-276b | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 6, profile class 17 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | + +**Table 9.7.6-1 – Limit mask definitions for each class mask** + +| Bit | Annex A | Annex B | | | | | | | Annex C | | +|---------------------------|----------------|--------------------|--------------------|---------------------------|--------------------|--------------------|--------------------|-------------------|------------------|-------------------| +| | 998
Annex A | 998-M1x
Annex B | 998-M2x
Annex B | 998ADE-
M2x
Annex B | 997-M1x
Annex B | 997-M1c
Annex B | 997-M2x
Annex B | HPE-M1
Annex B | 998-B
Annex C | 998-CO
Annex C | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 7, profile class 30 | | | | | | | | | | | +| 1 | D-32 | | E30-M2x-
NUS0 | ADE30-
M2x-
NUS0-A | | | E30-M2x-
NUS0 | 30-M1-
NUS0 | POTS-
138b | | +| 2 | D-48 | | E30-M2x-
NUS0-M | ADE30-
M2x-
NUS0-M | | | | | TCM-
ISDN | | +| 3 | | | | | | | | | POTS-
276b | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 8, profile class 30 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | + +NOTE – All unassigned bits are reserved by ITU. + +**Table 9.7.6-2 – VDSL2 US0 PSD masks definition** + +| Bit | G.993.2 Annex A US0MASK | +|----------------|-------------------------| +| Octet 1 | | +| 1 | EU-32 | +| 2 | EU-36 | +| 3 | EU-40 | +| 4 | EU-44 | +| 5 | EU-48 | +| 6 | EU-52 | +| 7 | EU-56 | +| 8 | EU-60 | + +**Table 9.7.6-2 – VDSL2 US0 PSD masks definition** + +| Bit | G.993.2 Annex A US0MASK | +|-----------------------------------------------------------------------------------------------------------------------------------------|-------------------------| +| Octet 2 | | +| 1 | EU-64 | +| 2 | EU-128 | +| 3 | Reserved by ITU | +| 4 | Reserved by ITU | +| 5 | Reserved by ITU | +| 6 | Reserved by ITU | +| 7 | Reserved by ITU | +| 8 | Reserved by ITU | +| Octet 3 | | +| 1 | ADLU-32 | +| 2 | ADLU-36 | +| 3 | ADLU-40 | +| 4 | ADLU-44 | +| 5 | ADLU-48 | +| 6 | ADLU-52 | +| 7 | ADLU-56 | +| 8 | ADLU-60 | +| Octet 4 | | +| 9 | ADLU-64 | +| 10 | ADLU-128 | +| 11 | Reserved by ITU | +| 12 | Reserved by ITU | +| 13 | Reserved by ITU | +| 14 | Reserved by ITU | +| 15 | Reserved by ITU | +| 16 | Reserved by ITU | +| NOTE 1 – Valid combinations of US0MASK and LIMITMASK are described in [ITU-T G.993.2]. | | +| NOTE 2 – More than one mask may be enabled simultaneously. If no US0 PSD masks are enabled, the line is configured without US0 support. | | + +### 9.7.7 xDSL channel configuration profile + +This managed entity contains the channel configuration profile for an xDSL line. An instance of this managed entity is created and deleted by the OLT. + +NOTE – If [ITU-T G.997.1] compatibility is required, bit rates should only be set to integer multiples of 1000 bit/s. The ONT may reject attempts to set other values for bit rate attributes. + +#### Relationships + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. (R, Set-by-create) (mandatory) (2 bytes) +- Minimum data rate:** This parameter specifies the minimum desired net data rate for the bearer channel. It is coded in bit/s. (R, W, Set-by-create) (mandatory) (4 bytes) +- Maximum data rate:** This parameter specifies the maximum desired net data rate for the bearer channel. It is coded in bit/s. (R, W, Set-by-create) (mandatory) (4 bytes) +- Rate adaptation ratio:** This attribute specifies the weight that should be taken into account when performing rate adaptation in the direction of the bearer channel. The attribute is defined as a percentage in the 0 to 100 range. The value 20, for example, means that 20% of the available data rate (in excess of the minimum data rate summed over all bearer channels) is assigned to this bearer channel and 80% to the other bearer channels. The OLT must assure that the sum of rate adaptation ratios over all bearers in one direction is 100%. (R, W, Set-by-create) (optional) (1 byte) +- Maximum interleaving delay:** This attribute is the maximum one-way interleaving delay introduced by the PMS-TC between the alpha and the beta reference points, in the direction of the bearer channel. The one-way interleaving delay is defined in individual xDSL Recommendations as $\text{cap}(S*D)/4$ ms, where S is the S factor, D is the interleaving depth, and $\text{cap}()$ denotes rounding to the next higher integer. xTUs choose S and D values such that the actual one-way interleaving delay does not exceed the configured maximum interleaving delay. +- The delay is coded in ms, varying from 2 to 63, with special meaning assigned to values 0, 1 and 255. The value 0 indicates no delay bound is imposed. The value 1 indicates the fast latency path is to be used in the G.992.1 operating mode, and S and D are to be selected such that $S \leq 1$ and $D = 1$ in G.992.2, G.992.3, G.992.4, G.992.5 and G.993.2 operating modes. The value 255 indicates a delay bound of 1 ms in G.993.2 operation. (R, W, Set-by-create) (mandatory) (1 byte) +- Data rate threshold upshift:** This attribute is a threshold on the cumulative data rate upshift achieved over one or more bearer channel data rate adaptations. An upshift rate change (DRT up) notification is issued by the PPTP xDSL UNI part 1 when the actual data rate exceeds the data rate at the last entry into showtime by more than the threshold. The data rate threshold is coded in bit/s. (R, W, Set-by-create) (mandatory for xDSL standards that use this attribute) (4 bytes) +- Data rate threshold downshift:** This attribute is a threshold on the cumulative data rate downshift achieved over one or more bearer channel data rate adaptations. A downshift rate change (DRT down) notification is issued by the PPTP xDSL UNI part 1 when the actual data rate is below the data rate at the last entry into showtime by more than the threshold. The data rate threshold is coded in bit/s. (R, W, Set-by-create) (mandatory for xDSL standards that use this attribute) (4 bytes) + +**Minimum reserved data rate:** This attribute specifies the desired minimum reserved net data rate for the bearer channel. The rate is coded in bit/s. This attribute is needed only if the rate adaptation mode is set to dynamic in the xDSL line configuration profile part 1. (R, W, Set-by-create) (optional) (4 bytes) + +**Minimum data rate in low power state:** This parameter specifies the minimum desired net data rate for the bearer channel during the low power state (L1/L2). The power management low power states L1 and L2 are defined in [b-ITU-T G.992.2] and [ITU-T G.992.3], respectively. The data rate is coded in bit/s. (R, W, Set-by-create) (mandatory) (4 byte) + +**Minimum impulse noise protection:** The INPmin attribute specifies the minimum impulse noise protection for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 4.3125 kHz. Impulse noise protection is expressed in DMT symbols with a subcarrier spacing of 4.3125 kHz. It can be 1/2 symbol or any integer number of symbols from 0 to 16, inclusive. + +If the xTU does not support the configured INPmin value, it uses the nearest supported impulse noise protection value greater than INPmin. + +| Value | INPmin | +|--------------|---------------------------| +| 1 | 0 symbols | +| 2 | 1/2 symbol | +| 3 | 1 symbol | +| 4 | 2 symbols | +| N | (N-2) symbols, 3 ≤ N ≤ 18 | + +(R, W, Set-by-create) (mandatory for xDSL standards that use this attribute) (1 byte) + +**Maximum bit error ratio:** This attribute specifies the desired maximum bit error ratio for the bearer channel. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. The bit error ratio is specified via the following values: + +| | | +|---|------------------| +| 1 | 10 -3 | +| 2 | 10 -5 | +| 3 | 10 -7 | + +(R, W, Set-by-create) (mandatory for standards that use this attribute) (1 byte) + +**Minimum impulse noise protection 8 kHz:** The INPmin8 attribute specifies the minimum impulse noise protection for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 8.625 kHz. It is only valid for [ITU-T G.993.2]. Impulse noise protection is expressed in DMT symbols with a subcarrier spacing of 8.625 kHz. It can take any integer value from 0 (default) to 16, inclusive. (R, W) (mandatory for [ITU-T G.993.2]) (1 byte) + +**Maximum delay variation:** The DVMAX attribute specifies the maximum value for delay variation allowed in an OLR procedure. Its value ranges from 1 (0.1 ms) to 254 (25.4 ms). The special value 255 specifies that no delay variation bound is imposed. (R, W) (optional: used by [ITU-T G.993.2]) (1 byte) + +**Channel initialization policy selection:** The CIPOLICY attribute specifies the policy to determine transceiver configuration at initialization. Valid values are 0..1, as defined in the Recommendations that use this attribute. (R, W) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.7.8 xDSL subcarrier masking downstream profile** + +This managed entity contains the subcarrier masking downstream profile for an xDSL line. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. (R, Set-by-create) (mandatory) (2 bytes) + +The four following attributes are bit maps that represent downstream mask values for subcarriers 1..128 (mask 1) through 385..512 (mask 4). The MSB of the first byte corresponds to the lowest numbered subcarrier, and the LSB of the last byte corresponds to the highest. Each bit position defines whether the corresponding downstream subcarrier is masked (1) or not masked (default value 0). + +NSCds is the highest numbered subcarrier that can be transmitted in the downstream direction. For [ITU-T G.992.3], [ITU-T G.992.4], and [ITU-T G.992.5], it is defined in the corresponding Recommendation. For [ITU-T G.992.1], NSCds = 256 and for [b-ITU-T G.992.2], NSCds = 128. + +**Downstream subcarrier mask 1:** (R, W, Set-by-create) (mandatory) (16 bytes) + +**Downstream subcarrier mask 2:** Subcarriers 129 to 256. (R, W) (mandatory for modems that support NSCds > 128) (16 bytes) + +**Downstream subcarrier mask 3:** Subcarriers 257 to 384. (R, W) (mandatory for modems that support NSCds > 256) (16 bytes) + +**Downstream subcarrier mask 4:** Subcarriers 385 to 512. (R, W) (mandatory for modems that support NSCds > 384) (16 bytes) + +**Mask valid:** This Boolean attribute controls and reports the operational status of the downstream subcarrier mask attributes. + +If this attribute is true (1), the downstream subcarrier mask represented in this ME has been impressed on the DSL equipment. + +If this attribute is false (0), the downstream subcarrier mask represented in this ME has not been impressed on the DSL equipment. The default value is false. + +The value of this attribute can be modified by the ONT and OLT, as follows: + +- If the OLT changes any of the four mask attributes or sets mask valid false, then mask valid is false. + +- If mask valid is false and the OLT sets mask valid true, the ONT impresses the downstream subcarrier mask data onto the DSL equipment. + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.7.9 xDSL subcarrier masking upstream profile** + +This managed entity contains the subcarrier masking upstream profile for an xDSL line. An instance of this managed entity is created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. (R, Set-by-create) (mandatory) (2 bytes) + +**Upstream subcarrier mask:** This attribute is a bit map representing upstream mask values for subcarriers 1 to 64. The MSB of byte 1 corresponds to subcarrier 1, and the LSB of byte 8 corresponds to subcarrier 64. Each bit position defines whether the corresponding downstream subcarrier is masked (1) or not masked (default value 0). + +Subcarrier number 1 is the lowest, and subcarrier number NSCus is the highest subcarrier that can be transmitted in the upstream direction. For [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5], it is defined in the corresponding Recommendation. For Annex A of [ITU-T G.992.1] and [b-ITU-T G.992.2], NSCus = 32 and for Annex B of [ITU-T G.992.1], NSCus = 64. (R, W, Set-by-create) (mandatory) (8 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.7.10 xDSL PSD mask profile** + +This managed entity contains a PSD mask profile for an xDSL line. An instance of this managed entity is created and deleted by the OLT. + +NOTE 1 – This managed entity was previously known as ADSL downstream PSD mask profile. The name was changed so that the same managed entity could be used for both upstream and downstream. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. (R, Set-by-create) (mandatory) (2 bytes) + +**PSD mask table:** This attribute is a table that defines the PSD mask applicable at the U-C2 reference point (downstream) or the U-R2 reference point (upstream). This mask may impose PSD restrictions in addition to the limit PSD mask defined in the relevant Recommendations ([ITU-T G.992.5], [ITU-T G.993.2]). + +NOTE 2 – In [ITU-T G.997.1], this attribute is called PSDMASKds (downstream) and PSDMASKus (upstream). In [ITU-T G.993.2], this attribute is called MIBMASKds (downstream) and MIBMASKus (upstream). The [ITU-T G.993.2] MIBMASKus does not include breakpoints to shape US0. + +The PSD mask is specified through a set of breakpoints. Each breakpoint comprises a two-byte subcarrier index $t$ , with a subcarrier spacing of 4.3125 kHz, and a one-byte PSD mask level at that subcarrier. The set of breakpoints can then be represented as $[(t_1, \text{PSD}_1), (t_2, \text{PSD}_2), \dots, (t_N, \text{PSD}_N)]$ . The PSD mask level is coded as 0 (0.0 dBm/Hz) to 190 (–95.0 dBm/Hz), in steps of 0.5 dB. + +The maximum number of downstream breakpoints is 32. In the upstream direction, the maximum number of breakpoints is 4 for [ITU-T G.992.3] and 16 for [ITU-T G.993.2]. The requirements for a valid set of breakpoints are defined in the relevant Recommendations ([ITU-T G.992.3], [ITU-T G.992.5], [ITU-T G.993.2]). + +Each table entry in this attribute comprises: + +- An entry number field. (1 byte, first entry numbered 1) +- A subcarrier index field, denoted $t$ . (2 bytes) +- A PSD mask level field. (1 byte) + +By default, the PSD mask table is empty. Entries are added or modified using the set action, which permits from one to as many as seven breakpoints to be addressed in a single message (Note 3). Setting a subcarrier entry with a valid PSD mask level implies insertion into the table or replacement of an existing entry. Setting an entry's PSD mask level to 0xFF implies deletion from the table. + +NOTE 3 – OMCI does not provide robust exception handling when more than one entry is included in a set command, and multiple values per set operation are not recommended. + +(R, W) (mandatory) (4N bytes where N is the number of breakpoints) + +**Mask valid:** This Boolean attribute controls and reports the status of the PSD mask attribute. + +As a status report, the value false (0) indicates that the PSD mask represented in this ME has not been impressed on the DSL equipment. The value true (1) indicates that the PSD mask represented in this ME has been impressed on the DSL equipment. + +This attribute behaves as follows: + +- If the OLT changes any of the PSD mask table entries or sets mask valid false, then mask valid is false. +- If mask valid is false and the OLT sets mask valid true, the ONT impresses the PSD mask data on the DSL equipment. + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +**Create, delete, get, get next, set** + +#### *Notifications* + +None. + +### **9.7.11 xDSL downstream RFI bands profile** + +This managed entity contains the downstream RFI bands profile for an xDSL line. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of the physical path termination point xDSL UNI. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. (R, Set-by-create) (mandatory) (2 bytes) + +**Downstream RFI bands table:** The RFIBANDS attribute is a table where each entry comprises: + +- An entry number field. (1 byte, first entry numbered 1) +- Subcarrier index 1 field. (2 bytes) +- Subcarrier index 2 field. (2 bytes) + +For [ITU-T G.992.5], this configuration attribute defines the subset of downstream PSD mask breakpoints, as specified in the downstream PSD mask, to be used to notch an RFI band. This subset consists of couples of consecutive subcarrier indices belonging to breakpoints: $[t_i; t_{i+1}]$ , corresponding to the low level of the notch. Interpolation around these points is defined in [ITU-T G.992.5]. + +For [ITU-T G.993.2], this attribute defines the bands where the PSD is to be reduced as specified in clause 7.2.1.2 of [ITU-T G.993.2]. Each band is represented by start and stop subcarrier indices with a subcarrier spacing of 4.3125 kHz. Up to 16 bands may be specified. This attribute defines the RFI bands for both upstream and downstream directions. + +Entries have default value 0 for both subcarrier index 1 and subcarrier index 2. Table entries for this attribute are added or modified using the set action. Setting an entry with a non-zero subcarrier index 1 and subcarrier index 2 implies insertion into the table or replacement of an existing entry. Setting an entry's subcarrier index 1 and subcarrier index 2 to 0 implies deletion from the table, if present. + +(R, W) (mandatory) (5N bytes where N is the number of RFI bands) + +**Bands valid:** This Boolean attribute controls and reports the operational status of the downstream RFI bands table. + +If this attribute is true (1), the downstream RFI bands table has been impressed on the DSL equipment. + +If this attribute is false (0), the downstream RFI bands table has not been impressed on the DSL equipment. The default value is false. + +This attribute can be modified by the ONT and OLT, as follows: + +- If the OLT changes any of the RFI bands table entries or sets bands valid false, then bands valid is false. +- If bands valid is false and OLT sets bands valid true, the ONT impresses the downstream RFI bands data onto the DSL equipment. + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +**Create, delete, get, get next, set** + +#### *Notifications* + +None. + +### **9.7.12 xDSL line inventory and status data part 1** + +This managed entity contains part 1 of the line inventory and status data for an xDSL line. The ONT automatically creates or deletes an instance of this managed entity upon the creation or deletion of a physical path termination point xDSL UNI part 1. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a physical path termination point xDSL UNI part 1. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL UNI. (R) (mandatory) (2 bytes) + +**xTU-C G.994.1 vendor ID:** This is the vendor ID as inserted by the xTU-C in the G.994.1 CL message. It comprises 8 octets, including a country code followed by a (regionally allocated) provider code, as defined in [ITU-T T.35]. (R) (mandatory) (8 bytes) + +**xTU-R G.994.1 vendor ID:** This is the vendor ID as inserted by the xTU-R in the G.994.1 CLR message. It comprises 8 binary octets, with the same format as the xTU-C G.994.1 vendor ID. (R) (mandatory) (8 bytes) + +**xTU-C system vendor ID:** This is the vendor ID as inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises 8 binary octets, with the same format as the xTU-C G.994.1 vendor ID. (R) (mandatory) (8 bytes) + +| | | +|----------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| xTU-R system vendor ID: | This is the vendor ID as inserted by the xTU-R in the embedded operations channel and overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises 8 binary octets, with the same format as the xTU-C G.994.1 vendor ID. (R) (mandatory) (8 bytes) | +| xTU-C version number: | This is the vendor-specific version number as inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises up to 16 binary octets. (R) (mandatory) (16 bytes) | +| xTU-R version number: | This is the vendor-specific version number as inserted by the xTU-R in the embedded operations channel or overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises up to 16 binary octets. (R) (mandatory) (16 bytes) | +| xTU-C serial number part 1: | The vendor-specific serial number inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4] comprises up to 32 ASCII characters. This attribute contains the first 16 characters. (R) (mandatory) (16 bytes) | +| xTU-C serial number part 2: | The vendor-specific serial number inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4] comprises up to 32 ASCII characters. This attribute contains the second 16 characters. (R) (mandatory) (16 bytes) | +| xTU-R serial number part 1: | The vendor-specific serial number inserted by the xTU-R in the embedded operations channel or overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4] comprises up to 32 ASCII characters. This attribute contains the first 16 characters. (R) (mandatory) (16 bytes) | +| xTU-R serial number part 2: | The vendor-specific serial number inserted by the xTU-R in the embedded operations channel or overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4] comprises up to 32 ASCII characters. This attribute contains the second 16 characters. (R) (mandatory) (16 bytes) | +| xTU-C self test results: | This parameter reports the xTU-C self test result. It is coded as a 32-bit integer. The most significant octet is 0 if the self test passed and 1 if it failed. The content of the other octets is vendor-discretionary and can be interpreted in combination with [ITU-T G.994.1] and the system vendor ID. (R) (mandatory) (4 bytes) | +| xTU-R self test results: | This parameter defines the xTU-R self test result. It is coded as a 32-bit integer. The most significant octet is 0 if the self test passed and 1 if it failed. The content of the other octets is vendor-discretionary and can be interpreted in combination with [ITU-T G.994.1] and the system vendor ID. (R) (mandatory) (4 bytes) | +| xTU-C transmission system capability: | This attribute lists xTU-C transmission system capabilities. It is a bit map, defined in Table 9.7.12-1.
NOTE 1 – An additional byte identifying VDSL2 capabilities is defined in the VDSL2 line inventory and status data part 1 managed entity.
(R) (mandatory) (7 bytes) | + +**xTU-R transmission system capability:** This attribute lists xTU-R transmission system capabilities. It is a bit map, defined in Table 9.7.12-1. + +NOTE 2 – An additional byte identifying VDSL2 capabilities is defined in the VDSL2 line inventory and status data part 2 managed entity. + +(R) (mandatory) (7 bytes) + +**Initialization success/failure cause:** This parameter represents the success or failure cause of the last full initialization performed on the line. It is coded as follows: + +- 0 Successful + - 1 Configuration error +This error occurs with inconsistencies in configuration parameters, e.g., when the line is initialized in an xDSL transmission system whose xTU does not support the configured maximum delay or the configured minimum or maximum data rate for one or more bearer channels. + - 2 Configuration not feasible on the line +This error occurs if the minimum data rate cannot be achieved on the line with the minimum noise margin, maximum PSD level, maximum delay and maximum bit error ratio for one or more bearer channels. + - 3 Communication problem +This error occurs, e.g., due to corrupted messages, bad syntax messages, if no common mode can be selected in the G.994.1 handshake procedure, or due to a timeout. + - 4 No peer xTU detected +This error occurs if the peer xTU is not powered or not connected or if the line is too long to allow detection of a peer xTU. + - 5 Any other or unknown initialization failure cause +- (R) (mandatory) (1 byte) + +*Actions* + +**Get** + +*Notifications* + +None. + +Table 9.7.12-1 describes the xTU transmission system capability attributes in xDSL status managed entities. It is a bit map (0 if not allowed, 1 if allowed) with the following definition. + +**Table 9.7.12-1 – xTU transmission system table** + +| Bit | Representation | +|---------|----------------------------------------------------------------------------------| +| Octet 1 | | +| 1 | [ANSI T1.PP.413] | +| 2 | Annex C of [ETSI TS 101 388] | +| 3 | G.992.1 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.1]) | +| 4 | G.992.1 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.1]) | +| 5 | G.992.1 operation over ISDN non-overlapped spectrum (Annex B of [ITU-T G.992.1]) | +| 6 | G.992.1 operation over ISDN overlapped spectrum (Annex B of [ITU-T G.992.1]) | + +**Table 9.7.12-1 – xTU transmission system table** + +| Bit | Representation | +|---------|-----------------------------------------------------------------------------------------------------------------| +| 7 | G.992.1 operation in conjunction with TCM-ISDN non-overlapped spectrum (Annex C of [ITU-T G.992.1]) | +| 8 | G.992.1 operation in conjunction with TCM-ISDN overlapped spectrum (Annex C of [ITU-T G.992.1]) | +| Octet 2 | | +| 9 | G.992.2 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.2]) | +| 10 | G.992.2 operation over POTS overlapped spectrum (Annex B of [ITU-T G.992.2]) | +| 11 | G.992.2 operation in conjunction with TCM-ISDN non-overlapped spectrum (Annex C of [ITU-T G.992.2]) | +| 12 | G.992.2 operation in conjunction with TCM-ISDN overlapped spectrum (Annex C of [b-ITU-T G.992.2]) | +| 13 | Reserved | +| 14 | Reserved | +| 15 | Reserved | +| 16 | Reserved | +| Octet 3 | | +| 17 | Reserved | +| 18 | Reserved | +| 19 | G.992.3 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.3]) | +| 20 | G.992.3 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.3]) | +| 21 | G.992.3 operation over ISDN non-overlapped spectrum (Annex B of [ITU-T G.992.3]) | +| 22 | G.992.3 operation over ISDN overlapped spectrum (Annex B of [ITU-T G.992.3]) | +| 23 | Reserved | +| 24 | Reserved | +| Octet 4 | | +| 25 | G.992.4 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.4]) | +| 26 | G.992.4 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.4]) | +| 27 | Reserved | +| 28 | Reserved | +| 29 | G.992.3 All digital mode operation with non-overlapped spectrum (Annex I of [ITU-T G.992.3]) | +| 30 | G.992.3 All digital mode operation with overlapped spectrum (Annex I of [ITU-T G.992.3]) | +| 31 | G.992.3 All digital mode operation with non-overlapped spectrum (Annex J of [ITU-T G.992.3]) | +| 32 | G.992.3 All digital mode operation with overlapped spectrum (Annex J of [ITU-T G.992.3]) | +| Octet 5 | | +| 33 | G.992.4 All digital mode operation with non-overlapped spectrum (Annex I of [ITU-T G.992.4]) | +| 34 | G.992.4 All digital mode operation with overlapped spectrum (Annex I of [ITU-T G.992.4]) | +| 35 | G.992.3 Reach extended operation over POTS, Mode 1 (non-overlapped, wide upstream) (Annex L of [ITU-T G.992.3]) | + +**Table 9.7.12-1 – xTU transmission system table** + +| Bit | Representation | +|-------------------|-------------------------------------------------------------------------------------------------------------------| +| 36 | G.992.3 Reach extended operation over POTS, Mode 2 (non-overlapped, narrow upstream) (Annex L of [ITU-T G.992.3]) | +| 37 | G.992.3 Reach extended operation over POTS, Mode 3 (overlapped, wide upstream) (Annex L of [ITU-T G.992.3]) | +| 38 | G.992.3 Reach extended operation over POTS, Mode 4 (overlapped, narrow upstream) (Annex L of [ITU-T G.992.3]) | +| 39 | G.992.3 Extended upstream operation over POTS non-overlapped spectrum (Annex M of [ITU-T G.992.3]) | +| 40 | G.992.3 Extended upstream operation over POTS overlapped spectrum (Annex M of [ITU-T G.992.3]) | +| Octet 6 | | +| 41 | G.992.5 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.5]) | +| 42 | G.992.5 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.5]) | +| 43 | G.992.5 operation over ISDN non-overlapped spectrum (Annex B of [ITU-T G.992.5]) | +| 44 | G.992.5 operation over ISDN overlapped spectrum (Annex B of [ITU-T G.992.5]) | +| 45 | Reserved | +| 46 | Reserved | +| 47 | G.992.5 All digital mode operation with non-overlapped spectrum (Annex I of [ITU-T G.992.5]) | +| 48 | G.992.5 All digital mode operation with overlapped spectrum (Annex I of [ITU-T G.992.5]) | +| Octet 7 | | +| 49 | G.992.5 All digital mode operation with non-overlapped spectrum (Annex J of [ITU-T G.992.5]) | +| 50 | G.992.5 All digital mode operation with overlapped spectrum (Annex J of [ITU-T G.992.5]) | +| 51 | G.992.5 Extended upstream operation over POTS non-overlapped spectrum (Annex M of [ITU-T G.992.5]) | +| 52 | G.992.5 Extended upstream operation over POTS overlapped spectrum (Annex M of [ITU-T G.992.5]) | +| 53 | Reserved | +| 54 | Reserved | +| 55 | Reserved | +| 56 | Reserved | +| Octet 8
(Note) | | +| 57 | G.993.2 region A (North America) (Annex A of [ITU-T G.993.2]) | +| 58 | G.993.2 region B (Europe) (Annex B of [ITU-T G.993.2]) | +| 59 | G.993.2 region C (Japan) (Annex C of [ITU-T G.993.2]) | +| 60 | Reserved | +| 61 | Reserved | +| 62 | Reserved | +| 63 | Reserved | + +**Table 9.7.12-1 – xTU transmission system table** + +| Bit | Representation | +|-----|----------------| +| 64 | Reserved | + +NOTE – For backward compatibility reasons, the eighth octet of this table is represented as a separate attribute in separate managed entities. + +### 9.7.13 xDSL line inventory and status data part 2 + +This managed entity contains part 2 of the line inventory and status data for an xDSL line. The ONT automatically creates or deletes an instance of this managed entity upon the creation or deletion of a physical path termination point xDSL UNI part 1. + +NOTE 1 – [ITU-T G.997.1] specifies that bit rate attributes have granularity of 1000 bit/s. If G.997.1 compliance is required, the ONT should only report values with this granularity. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a physical path termination point xDSL UNI part 1. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL UNI. (R) (mandatory) (2 bytes) + +**xDSL transmission system:** This parameter defines the transmission system in use. It is a bit map, defined in Table 9.7.12-1. (R) (mandatory) (7 bytes) + +NOTE 2 – An additional byte identifying VDSL2 capabilities in use is defined in the VDSL2 line inventory and status data part 1 managed entity. (R) (mandatory) (7 bytes) + +**Line power management state:** The line has four possible power management states: + +- 0 L0: Synchronized – This line state occurs when the line has full transmission (i.e., showtime). +- 1 L1: Power down data transmission – This line state occurs when there is transmission on the line but the net data rate is reduced (e.g., only for OAM and higher layer connection and session control). This state applies to [b-ITU-T G.992.2] only. +- 2 L2: Power down data transmission – This line state occurs when there is transmission on the line but the net data rate is reduced (e.g., only for OAM and higher layer connection and session control). This state applies to [ITU-T G.992.3] and [ITU-T G.992.4] only. +- 3 L3: No power – This line state occurs when no power is transmitted on the line at all. + +(R) (mandatory) (1 byte) + +| | | +|-------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Downstream line attenuation: |

The LATNds attribute is the measured difference in the total power transmitted by the xTU-C and the total power received by the xTU-R over all subcarriers during diagnostics mode and initialization. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB) dB. The special value 0xFFFF indicates that line attenuation is out of range.

NOTE 3 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 managed entity. In a G.993.2 context, the downstream line attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead.

(R) (mandatory) (2 bytes)

| +| Upstream line attenuation: |

The LATNus attribute is the measured difference in the total power transmitted by the xTU-R and the total power received by the xTU-C over all subcarriers during diagnostics mode and initialization. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB). The special value 0xFFFF indicates that line attenuation is out of range.

NOTE 4 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 managed entity. In a G.993.2 context, the upstream line attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. (R) (mandatory) (2 bytes)

| +| Downstream signal attenuation: |

The SATNds attribute is the measured difference in the total power transmitted by the xTU-C and the total power received by the xTU-R over all subcarriers during showtime. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB). The special value 0xFFFF indicates that signal attenuation is out of range.

NOTE 5 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 managed entity. In a [ITU-T G.993.2] context, the downstream signal attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. (R) (mandatory) (2 bytes)

| +| Upstream signal attenuation: |

The SATNus attribute is the measured difference in the total power transmitted by the xTU-R and the total power received by the xTU-C over all subcarriers during showtime. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB). The special value 0xFFFF indicates that signal attenuation is out of range.

NOTE 6 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 managed entity. In a [ITU-T G.993.2] context, the upstream signal attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. (R) (mandatory) (2 bytes)

| +| Downstream signal-to-noise ratio margin: |

The downstream signal-to-noise ratio margin SNRMds is the maximum increase of noise power received at the xTU-R, such that the BER requirements can still be met for all downstream bearer channels. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes)

| + +| | | +|------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Upstream signal-to-noise ratio margin: | The upstream signal-to-noise ratio margin SNRMus is the maximum increase of noise power received at the xTU-C, such that the BER requirements can still be met for all upstream bearer channels. The attribute value ranges from 0 (-64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) | +| Downstream maximum attainable data rate: | This parameter indicates the maximum downstream net data rate currently attainable. The rate is coded in bit/s. (R) (mandatory) (4 bytes) | +| Upstream maximum attainable data rate: | This parameter indicates the maximum upstream net data rate currently attainable. The rate is coded in bit/s. (R) (mandatory) (4 bytes) | +| Downstream actual power spectrum density: | This parameter is the average downstream transmit power spectrum density over the subcarriers in use (subcarriers to which downstream user data are allocated) delivered by the xTU-C at the U-C reference point, at the instant of measurement. The attribute value ranges from 0 (-90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) | +| Upstream actual power spectrum density: | The ACTPSDus attribute is the average upstream transmit power spectrum density over the subcarriers in use (subcarriers to which upstream user data are allocated) delivered by the xTU-R at the U-R reference point, at the instant of measurement. The attribute value ranges from 0 (-90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) | +| Downstream actual aggregate transmit power: | This parameter is the total amount of transmit power delivered by the xTU-C at the U-C reference point, at the instant of measurement. The attribute value ranges from 0 (-31.0 dBm ) to 620 (+31.0 dBm). The special value 0xFFFF indicates that the parameter is out of range.
NOTE 7 – The downstream nominal aggregate transmit power may be taken as a best estimate of the parameter.
(R) (mandatory) (2 bytes) | +| Upstream actual aggregate transmit power: | This parameter is the total amount of transmit power delivered by the xTU-R at the U-R reference point, at the instant of measurement. The attribute value ranges from 0 (-31.0 dBm ) to 620 (+31.0 dBm). The special value 0xFFFF indicates that the parameter is out of range.
NOTE 8 – The upstream nominal aggregate transmit power may be taken as a best estimate of the parameter.
(R) (mandatory) (2 bytes) | +| Initialization – last state transmitted downstream: | This parameter represents the last successful transmitted initialization state in the downstream direction in the last full initialization performed on the line. Initialization states are defined in the individual xDSL Recommendations and are counted from 0 (if [ITU-T G.994.1] is used) or 1 (if [ITU-T G.994.1] is not used) up to showtime. This parameter must be interpreted along with the xDSL transmission system capabilities. | + +This parameter is available only when, after a failed full initialization, line diagnostic procedures are activated on the line. Line diagnostic procedures can be activated by the operator of the system (through the line state forced line configuration parameter) or autonomously by the xTU-C or xTU-R. + +(R) (mandatory) (1 byte) + +##### **Initialization – last state transmitted upstream:** + +This parameter represents the last successful transmitted initialization state in the upstream direction in the last full initialization performed on the line. Initialization states are defined in the individual xDSL Recommendations and are counted from 0 (if [ITU-T G.994.1] is used) or 1 (if [ITU-T G.994.1] is not used) up to showtime. This parameter must be interpreted along with the xDSL transmission system capabilities. + +This parameter is available only when, after a failed full initialization, line diagnostic procedures are activated on the line. Line diagnostic procedures can be activated by the operator of the system (through the line state forced line configuration parameter) or autonomously by the xTU-C or xTU-R. + +(R) (mandatory) (1 byte) + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.7.14 xDSL line inventory and status data part 3** + +This managed entity extends the attributes defined in the xDSL line inventory and status data parts 1 and 2. This ME reports downstream attributes. + +#### *Relationships* + +This is one of the status MEs pointed to by a physical path termination point xDSL managed entity. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of a physical path termination point xDSL that supports these attributes. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL managed entity. (R) (mandatory) (2 bytes) + +**TSSpsds table:** This table contains downstream transmit spectrum shaping attributes expressed as the set of breakpoints exchanged during [ITU-T G.994.1]. Each breakpoint consists of a two-byte subcarrier index and the associated shaping attribute. The shaping attribute is one byte, an integer value in the 0 to 126 range, represented as a multiple of -0.5 dB. The special value 127 indicates that the subcarrier is not transmitted. (R) (mandatory) (3N bytes, where N is the number of breakpoints) + +**HLINSCds:** This attribute is the scale factor to be applied to the downstream Hlin(f) values. It is coded as a 16-bit unsigned integer. This attribute is only available after a loop diagnostic procedure. (R) (mandatory) (2 bytes) + +**HLINpsds table:** This attribute is an array of complex coefficients $\{a, b\}$ that represent the downstream transfer function Hlin(f) in linear form. Each array entry represents $Hlin(f) = i * HLINGds * \Delta f$ for a particular subcarrier group index $i$ , ranging from 0 to $\min(NSds, 511)$ . Hlin(f) may be reconstructed from the array as $((HLINSCds/2^{15}) * ((a(i) + j*b(i))/2^{15}))$ , where $a(i)$ and $b(i)$ are 2s complement integers in the range $(-2^{15} + 1)$ to $(+2^{15} - 1)$ . The granularity of $a$ and $b$ depends on the scale factor. + +The special value $a(i) = b(i) = -2^{15}$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the attenuation is out of range to be represented. + +This attribute is only available after a loop diagnostic procedure. (R) (mandatory) (4N bytes, where N is the number of subcarrier groups) + +**HLGMTds:** After a loop diagnostic procedure, this attribute contains the number of symbols used to measure the downstream Hlog(f) values. It is a 16-bit unsigned value that corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a one-second interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**HLGpsds table:** The HLGpsds attribute contains an array of numbers $m(i)$ , where $i$ is a particular subcarrier group index, ranging from 0 to $\min(NSds, 511)$ , and $m$ lies in the range 0..1022, with a granularity of 0.1 dB. The downstream transfer function Hlog(f) can be reconstructed by the OLT management client as $(6 - m(i)/10)$ dBm/Hz, with a range from +6 to approximately -96 dBm/Hz. + +The special value $m = 1023$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the attenuation is out of range to be represented. + +(R) (mandatory) (2N bytes, where N is the number of subcarrier groups) + +**QLNMTds:** After a loop diagnostic procedure, the quiet line noise PSD measurement time attribute contains the number of symbols used to measure the downstream QLN(f) values. It is a 16-bit unsigned value that corresponds to the value specified in the Recommendation (e.g., the number of symbols in a one-second interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**QLNpsds table:** The quiet line noise PSD attribute contains an array of numbers $n(i)$ , where $i$ is a subcarrier group index, ranging from 0 to $\min(NSds, 511)$ , and $n$ lies in the range 0..254, with granularity 0.5 dB. The downstream quiet line noise function QLN(f) can be reconstructed by the OLT management client as $(-23 - n(i)/2)$ dBm/Hz, with a range from -150 to -23 dBm/Hz. + +The special value $n = 255$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the noise PSD is out of range to be represented. + +(R) (mandatory) (N bytes, where N is the number of subcarrier groups) + +##### **SNRMTds:** + +After a loop diagnostic procedure, the SNR measurement time attribute contains the number of symbols used to measure the downstream SNR(f) values. It is a 16-bit unsigned value that corresponds to the value specified in the Recommendation (e.g., the number of symbols in a one-second interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +##### **SNRpsds table:** + +The SNRpsds attribute contains an array of numbers $snr(i)$ , where $i$ is a subcarrier group index, ranging from 0 to $\min(NSds, 511)$ , and $snr$ lies in the range 0..254, with a granularity of 0.5 dB. The downstream SNR function SNR(f), can be reconstructed by the OLT management client as $(-32 + snr(i)/2)$ dBm/Hz, with a range from -160 to -32 dBm/Hz. + +The special value $snr = 255$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the noise PSD is out of range to be represented. + +(R) (mandatory) (N bytes, where N is the number of subcarrier groups) + +##### **BITSpsds table:** + +This attribute reports the downstream bits allocation table per subcarrier. It is an array of values in the range 0..15 for subcarriers 0..NSds. Entries for subcarriers out of the downstream medley set are set to 0. (R) (mandatory) (N bytes, where N is the number of subcarriers) + +##### **GAINspds table:** + +This attribute contains the downstream gain allocation table per subcarrier. It is an array of integer values in the range 0..4093 for subcarriers 0..NSds. The gain is represented as a multiple of 1/512 on a linear scale. Entries for subcarriers out of the downstream medley set are set to 0. (R) (mandatory) (2N bytes, where N is the number of subcarriers) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### **9.7.15 xDSL line inventory and status data part 4** + +This managed entity extends the attributes defined in the xDSL line inventory and status data parts 1, 2 and 3. This ME reports upstream attributes. + +#### *Relationships* + +This is one of the status data MEs pointed to by a physical path termination point xDSL managed entity. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of a physical path termination point xDSL that supports these attributes. + +#### *Attributes* + +| | | +|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL managed entity. (R) (mandatory) (2 bytes) | +| TSSpsus table: | This attribute contains the upstream transmit spectrum shaping attributes, expressed as the set of breakpoints exchanged during [ITU-T G.994.1]. Each breakpoint consists of a two-byte subcarrier index and the associated shaping attribute. The shaping attribute is one byte, a value in the range 0..126, representing a multiple of -0.5 dB. The special value 127 indicates that the subcarrier is not transmitted. (R) (mandatory) (3N bytes, where N is the number of breakpoints) | +| HLINSCus: | This attribute is a 16-bit unsigned integer, the scale factor to be applied to the upstream Hlin(f) values. It is only available after a loop diagnostic procedure. (R) (mandatory) (2 bytes) | +| HLINpsus table: | This attribute is an array of complex upstream Hlin(f) values in linear scale. It is coded in the same way as the related downstream attribute HLINpsds (see xDSL line inventory and status data part 3). This attribute is only available after a loop diagnostic procedure. (R) (mandatory) (4N bytes, where N is the number of subcarrier groups) | +| HLOGMTus: | After a loop diagnostic procedure, this attribute contains the number of symbols used to measure the upstream Hlog(f) values. Its value corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1-second interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) | +| HLOGpsus table: | This attribute is an array of real upstream Hlog(f) values. It is coded in the same way as the related downstream attribute HLOGpsds (see xDSL line inventory and status data part 3). (R) (mandatory) (2N bytes, where N is the number of subcarrier groups) | +| QLNMTus: | After a loop diagnostic procedure, the quiet line noise PSD measurement attribute contains the number of symbols used to measure the upstream QLN(f) values. Its value corresponds to the value specified in the Recommendation (e.g., the number of symbols in a 1-second interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) | +| QLNpsus table: | The quiet line noise attribute represents an array of real upstream QLN(f) values. It is coded in the same way as the related downstream attribute QLNpsds (see xDSL line inventory and status data part 3). (R) (mandatory) (N bytes, where N is the number of subcarrier groups) | +| SNRMTus: | After a loop diagnostic procedure, the SNR measurement time attribute reports the number of symbols used to measure the upstream SNR(f) values. Its value corresponds to the value specified in the Recommendation (e.g., the number of symbols in a 1-second interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) | + +| | | +|------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| SNRpsus table: | This attribute is an array of real upstream SNR(f) values. It is coded in the same way as the related downstream attribute SNRpsds (see xDSL line inventory and status data part 3). (R) (mandatory) (N bytes, where N is the number of subcarrier groups) | +| BITSpsus table: | This attribute contains the upstream bits allocation table per subcarrier. It is an array in the range 0..15 for subcarriers 0..NSus. Entries for subcarriers out of the upstream medley set are set to 0. (R) (mandatory) (N bytes, where N is the number of subcarriers) | +| GAINspus table: | This attribute contains the upstream gains allocation table per subcarrier. It is an array in the range 0..4093 for subcarriers 0..NSus. The gain is represented as a multiple of 1/512 on a linear scale. Entries for subcarriers out of the upstream medley set are set to 0. (R) (mandatory) (2N bytes, where N is the number of subcarriers) | + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### **9.7.16 VDSL2 line inventory and status data part 1** + +This managed entity extends the other xDSL line inventory and status data MEs with attributes specific to VDSL2. This ME contains general and downstream attributes. + +#### *Relationships* + +This is one of the status data MEs pointed to by a physical path termination point xDSL managed entity. It is required only if VDSL2 is supported by the PPTP. The ONT automatically creates or deletes an instance of this managed entity upon creation and deletion of a physical path termination point xDSL that supports these attributes. + +#### *Attributes* + +| | | +|----------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL managed entity. (R) (mandatory) (2 bytes) | +| VDSL2 transmission system capability xTU-C: | This attribute extends the xTU-C transmission system capability attribute of the xDSL line inventory and status data part 1 to include xTU-C VDSL2 capabilities. It is defined by bits 57..64 of Table 9.7.12-1. (R) (mandatory) (1 byte) | +| VDSL2 transmission system: | This attribute reports the transmission system in use. It extends the xDSL transmission system attribute of the xDSL line inventory and status data part 2 managed entity with a byte that includes VDSL2 capabilities currently in use. It is defined by bits 57..64 of Table 9.7.12-1. (R) (mandatory) (1 byte) | + +**VDSL2 profile:** This attribute identifies the profile in use. It is a bit map (0 if not allowed, 1 if allowed) with the following definition: + +| Bit | Meaning | +|------------|----------------------| +| 1 (LSB) | G.993.2 profile 8a. | +| 2 | G.993.2 profile 8b. | +| 3 | G.993.2 profile 8c. | +| 4 | G.993.2 profile 8d. | +| 5 | G.993.2 profile 12a. | +| 6 | G.993.2 profile 12b. | +| 7 | G.993.2 profile 17a. | +| 8 | G.993.2 profile 30a. | + +(R) (mandatory) (1 byte) + +**VDSL2 limit PSD mask and bandplan:** This attribute defines the limit PSD mask and band plan in use. It is a bit map as defined by Table 9.7.6-1. (R) (mandatory) (8 bytes) + +**VDSL2 US0 PSD mask:** This attribute defines the US0 PSD mask in use. It is a bit map as defined by Table 9.7.6-2. (R) (mandatory) (4 bytes) + +**ACTSNRMODEds:** This attribute indicates whether transmitter referred virtual noise is active on the line in the downstream direction. + +- 1 Virtual noise inactive. +- 2 Virtual noise active. + +(R) (mandatory) (1 byte) + +The following four attributes have similar definitions. In each case, valid attribute values are 1, 2, 4, 8. In ADSL applications, the corresponding value is fixed at 1, and therefore need not be specified. For VDSL2, it is equal to the size of the subcarrier group used to compute these attributes (see clause 11.4.1 of [ITU-T G.993.2]). + +**HLINGds:** This attribute contains the number of subcarriers per group used to report HLINpsds. (R) (mandatory) (1 byte) + +**HLOGGds:** This attribute contains the number of subcarriers per group used to report HLOGpsds. (R) (mandatory) (1 byte) + +**QLNGds:** This attribute contains the number of subcarriers per group used to report QLNpsds. (R) (mandatory) (1 byte) + +**SNRGds:** This attribute contains the number of subcarriers per group used to report SNRpsds. (R) (mandatory) (1 byte) + +**MREFPSDds table:** The downstream medley reference PSD table contains the set of breakpoints exchanged in the MREFPSDds fields of the O-PRM message of [ITU-T G.993.2]. + +The format is similar to that specified for the PSD descriptor in [ITU-T G.993.2]. In [ITU-T G.993.2], the first byte gives the size of the table, each entry of which is three bytes. In the OMCI definition, the first byte is omitted, because the size of the table is known from the response to the get command. + +(R) (mandatory) (3N bytes, where N is the number of breakpoints) + +**TRELLISds:** This attribute reports whether trellis coding is in use in the downstream direction. + +0 Trellis not used. +1 Trellis used. + +(R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) +(1 byte) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### **9.7.17 VDSL2 line inventory and status data part 2** + +This managed entity extends the other xDSL line inventory and status data MEs with attributes specific to VDSL2. This ME contains upstream attributes. + +#### *Relationships* + +This is one of the status data MEs pointed to by a physical path termination point xDSL managed entity. It is required only if VDSL2 is supported by the PPTP. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of a physical path termination point xDSL that supports these attributes. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL managed entity. (R) (mandatory) (2 bytes) + +**VDSL2 transmission system capability xTU-R:** This attribute extends the xTU-R transmission system capability attribute of the xDSL line inventory and status data part 1 to include xTU-R VDSL2 capabilities. It is a bit map, specifically bits 57..64 of Table 9.7.12-1. (R) (mandatory) (1 byte) + +**ACTSNRMODEus:** This attribute indicates whether transmitter referred virtual noise is active on the line in the upstream direction. + +1 Virtual noise inactive. +2 Virtual noise active. + +(R) (mandatory) (1 byte) + +**UPBOKLE:** This attribute contains the estimated electrical length expressed in dB at 1 MHz, $kl_0$ (see O-UPDATE in clause 12.3.3.2.1.2 of [ITU-T G.993.2]). This is the final electrical length that would be sent from the VTU-O to the VTU-R if the electrical length were not forced by the OLT. The value lies in the range 0 (0.0 dB) to 1280 (128.0 dB). (R) (mandatory) (2 bytes) + +The following four attributes have similar definitions. In each case, valid attribute values are 1, 2, 4, 8. In ADSL applications, the corresponding value is fixed at 1, and therefore need not be specified. For VDSL2, it is equal to the size of the subcarrier group used to compute these attributes (see clause 11.4.1 of [ITU-T G.993.2]). + +**HLINGus:** This attribute is the number of subcarriers per group used to report HLINpsus. (R) (mandatory) (1 byte) + +**HLOGGus:** This attribute is the number of subcarriers per group used to report HLOGpsus. (R) (mandatory) (1 byte) + +**QLNGus:** This attribute is the number of subcarriers per group used to report QLNpsus. (R) (mandatory) (1 byte) + +**SNRGus:** This attribute is the number of subcarriers per group used to report SNRpsus. (R) (mandatory) (1 byte) + +**MREFPSDus table:** The upstream medley reference PSD attribute contains the set of breakpoints exchanged in the MREFPSDus fields of the R-PRM message of [ITU-T G.993.2]. + +The format is similar to that specified for the PSD descriptor in [ITU-T G.993.2]. In [ITU-T G.993.2], the first byte gives the size of the table, each entry of which is three bytes. In the OMCI definition, the first byte is omitted, because the size of the table is known from the response to the get command. + +(R) (mandatory) (3N bytes, where N is the number of breakpoints) + +**TRELLISus:** This attribute reports whether trellis coding is in use in the upstream direction. + +0 Trellis not used. + +1 Trellis used. + +(R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) + +**ACTUALCE:** This attribute reports the cyclic extension used on the line. It is coded as an unsigned integer from 2 to 16 in units of $N/32$ samples, where $2N$ is the IDFT size. (R) (mandatory) (1 byte) + +*Actions* + +**Get, get next** + +*Notifications* + +None. + +### 9.7.18 VDSL2 line inventory and status data part 3 + +This managed entity extends the other xDSL line inventory and status data MEs with attributes specific to VDSL2. This ME contains per-band attributes for both directions. These same attributes are defined in the xDSL line inventory and status data part 2 managed entity, but only for a single band. [ITU-T G.993.2] allows for VDSL2 to have as many as five bands upstream and as many as five bands downstream. + +#### *Relationships* + +This is one of the status data MEs pointed to by a physical path termination point xDSL managed entity. It is required only if VDSL2 is supported by the PPTP. The ONT automatically creates or deletes an instance of this managed entity upon creation or deletion of a physical path termination point xDSL that supports these attributes. + +#### *Attributes* + +| | | +|------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL managed entity. (R) (mandatory) (2 bytes) | +| Upstream bands count: | This attribute reports the number of upstream bands. It can be used to filter the upstream attributes. All upstream attributes are arrays of per-band entries, of which the first upstream bands count are populated. The content of the arrays for unused frequency bands is unspecified. The original attributes were allocated for as many as four upstream bands, US0, 1, 2, 3; optional extended attributes have been added to accommodate the possibility that five upstream bands may be needed. (R) (mandatory) (1 byte) | +| Downstream bands count: | This attribute reports the number of downstream bands. It can be used to filter the downstream attributes. All downstream attributes are arrays of per-band entries, of which the first downstream bands count are populated. The content of the arrays for unused frequency bands is unspecified. The original attributes were allocated for as many as three upstream bands, DS1, 2, 3; optional extended attributes have been added to accommodate the possibility that five downstream bands may be needed. (R) (mandatory) (1 byte) | +| Downstream line attenuation per band: | The LATNd attribute is defined per usable band. It is the measured difference in the total power transmitted in this band by the xTU-C and the total power received in this band by the xTU-R over all subcarriers of this band during loop diagnostic mode and initialization. The upstream line attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates the line attenuation per band is out of range to be represented. (R) (mandatory) (3 bands * 2 bytes = 6 bytes) | +| Upstream line attenuation per band: | The LATNu attribute is defined per usable band. It is the measured difference in the total power transmitted in this band by the xTU-R and the total power received in this band by the xTU-C over all subcarriers of this band during loop diagnostic mode and initialization. The upstream line attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates that line attenuation per band is out of range to be represented. (R) (mandatory) (4 bands * 2 bytes = 8 bytes) | +| Downstream signal attenuation per band: | The SATNd attribute is defined per usable band. It is the measured difference in the total power transmitted in this band by the xTU-C and the total power received in this band by the xTU-R over all subcarriers of this band during showtime. The downstream signal attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates that signal attenuation per band is out of range to be represented. | + +NOTE 1 – During showtime, only a subset of the subcarriers may be transmitted by the xTU-C, as compared to loop diagnostic mode and initialization. Therefore, the downstream signal attenuation may be significantly lower than the downstream line attenuation. + +(R) (mandatory) (3 bands \* 2 bytes = 6 bytes) + +**Upstream signal attenuation per band:** The SATNus attribute is defined per usable band. It is the measured difference in the total power transmitted in this band by the xTU-R and the total power received in this band by the xTU-C over all subcarriers of this band during showtime. The upstream signal attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates the signal attenuation per band is out of range to be represented. + +NOTE 2 – During showtime, only a subset of the subcarriers may be transmitted by the xTU-R, as compared to loop diagnostic mode and initialization. Therefore, the upstream signal attenuation may be significantly lower than the upstream line attenuation. + +(R) (mandatory) (4 bands \* 2 bytes = 8 bytes) + +**Downstream signal-to-noise ratio margin per band:** The SNRMpbds attribute is defined per usable band. The downstream signal to noise ratio margin per band is the maximum increase of noise power received at the xTU-R, such that the BER requirements are met for all downstream bearer channels. Each array value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range to be represented. (R) (mandatory) (3 bands \* 2 bytes = 6 bytes) + +**Upstream signal-to-noise ratio margin per band:** The SNRMpbus attribute is defined per usable band. The upstream signal to noise ratio margin per band is the maximum increase of noise power received at the xTU-C, such that the BER requirements are met for all upstream bearer channels. Each array value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range to be represented. (R) (mandatory) (4 bands \* 2 bytes = 8 bytes) + +**Downstream line attenuation extension:** This attribute extends LATNds when more than three downstream bands are used. It is defined in the same way as the downstream line attenuation per band attribute. (R) (optional) (2 bands \* 2 bytes = 4 bytes) + +**Upstream line attenuation extension:** This attribute extends LATNus when more than four upstream bands are used. It is defined in the same way as the upstream line attenuation per band attribute. (R) (optional) (1 band \* 2 bytes = 2 bytes) + +**Downstream signal attenuation extension:** This attribute extends SATNds when more than three downstream bands are used. It is defined in the same way as the downstream signal attenuation per band attribute. (R) (optional) (2 bands \* 2 bytes = 4 bytes) + +**Upstream signal attenuation extension:** This attribute extends SATNus when more than four upstream bands are used. It is defined in the same way as the upstream signal attenuation per band attribute. (R) (optional) (1 band \* 2 bytes = 2 bytes) + +**Downstream signal-to-noise ratio margin extension:** This attribute extends SNRMPbds when more than three downstream bands are used. It is defined in the same way as the downstream signal-to-noise ratio margin per band attribute. (R) (optional) (2 bands \* 2 bytes = 4 bytes) + +**Upstream signal-to-noise ratio margin extension:** This attribute extends SNRMPbus when more than four upstream bands are used. It is defined in the same way as the upstream signal-to-noise ratio margin per band attribute. (R) (optional) (1 band \* 2 bytes = 2 bytes) + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.7.19 xDSL channel downstream status data** + +This managed entity contains the xDSL channel downstream status data for an xDSL line. The ONT automatically creates or deletes instances of this managed entity upon the creation or deletion of a physical path termination point xDSL UNI part 1. + +NOTE – [ITU-T G.997.1] specifies that bit rate attributes have granularity of 1000 bit/s. If [ITU-T G.997.1] compliance is required, the ONT should only report values with this granularity. + +#### *Relationships* + +One or more instances of this managed entity is associated with an instance of a physical path termination point xDSL UNI part 1. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The two most significant bits of the first byte are the bearer channel ID. Excluding the first two bits of the first byte, the remaining part of the managed entity ID is identical to that of this ME's parent physical path termination point xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Actual interleaving delay:** This attribute is the actual one-way interleaving delay introduced by the PMS-TC between the alpha and beta reference points, excluding delay in L1 and L2 state. In L1 and L2 state, the attribute contains the interleaving delay in the previous L0 state. For ADSL, this attribute is derived from the S and D attributes as $\text{cap}(S*D)/4$ ms, where S is the number of symbols per codeword, D is the interleaving depth and cap() denotes rounding to the next higher integer. For [ITU-T G.993.2], this attribute is computed according to the formula in clause 9.7 of [ITU-T G.993.2]. The actual interleaving delay is coded in ms, rounded to the nearest ms. (R) (mandatory) (1 byte) + +**Actual data rate:** This parameter reports the actual net data rate the bearer channel is operating at, excluding the rate in L1 and L2 states. In L1 or L2 states, the parameter contains the net data rate in the previous L0 state. The data rate is coded in bit/s. (R) (mandatory) (4 bytes) + +| | | +|--------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Previous data rate: | This parameter reports the previous net data rate the bearer channel was operating at just before the latest rate change event occurred, excluding transitions between the L0 state and the L1 or L2 states. A rate change can occur at a power management state transition, e.g., at full or short initialization, fast retrain, or power down, or at a dynamic rate adaptation. The rate is coded in bit/s (R) (mandatory) (4 bytes) | +| Actual impulse noise protection: |

The ACTINP attribute reports the actual impulse noise protection (INP) on the bearer channel in the L0 state. In the L1 or L2 state, the attribute contains the INP in the previous L0 state.

For ADSL, this value is computed according to the formula specified in the relevant Recommendation based on the actual framing attributes. [ITU-T G.993.2] VDSL2 specifies no means to retrieve the impulse noise protection estimated by the xTU-R receiver. Therefore, the far-end ACTINP is computed according to the INP_no_erasure formula.

The value of this attribute is a number of DMT symbols, with a granularity of 0.1 symbols. Its range is from 0 (0.0 symbols) to 254 (25.4 symbols). The special value 255 indicates an ACTINP higher than 25.4.

(R) (mandatory) (1 byte)

| +| Actual size of Reed-Solomon codeword: | The NFEC attribute reports the actual Reed-Solomon codeword size used in the latency path in which the bearer channel is transported. The value is coded in bytes and ranges from 0..255. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | +| Actual number of Reed-Solomon redundancy bytes: | The RFEC attribute reports the actual number of Reed-Solomon redundancy bytes per codeword used in the latency path in which the bearer channel is transported. The value is coded in bytes and ranges from 0..16. The value 0 indicates no Reed-Solomon coding. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | +| Actual number of bits per symbol: | The LSYMB attribute reports the actual number of bits per symbol assigned to the latency path in which the bearer channel is transported, excluding trellis overhead. The value is coded in bits and ranges from 0..65535. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (2 bytes) | +| Actual interleaving depth: | The INTLVDEPTH attribute reports the actual depth of the interleaver used in the latency path in which the bearer channel is transported. The value ranges from 1..4096 in steps of 1. The value 1 indicates no interleaving. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (2 bytes) | +| Actual interleaving block length: | The INTLVBLOCK attribute reports the actual block length of the interleaver used in the latency path in which the bearer channel is transported. The value ranges from 4..255 in steps of 1. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | + +**Actual latency path:** The LPATH attribute reports the index of the actual latency path in which the bearer channel is transported. Valid values are 0..3. In [ITU-T G.992.1], the fast path is mapped to latency index 0; the interleaved path to index 1. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.7.20 xDSL channel upstream status data** + +This managed entity contains the xDSL channel upstream status data for an xDSL line. The ONT automatically creates or deletes instances of this managed entity upon the creation or deletion of a physical path termination point xDSL UNI part 1. + +#### *Relationships* + +One or more instances of this managed entity is associated with an instance of a physical path termination point xDSL UNI part 1. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The two most significant bits of the first byte are the bearer channel ID. Excluding the first two bits of the first byte, the remaining part of the managed entity ID is identical to that of this ME's parent physical path termination point xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Actual interleaving delay:** This attribute is the actual one-way interleaving delay introduced by the PMS-TC between the alpha and beta reference points, excluding the L1 and L2 states. In L1 and L2 state, this attribute contains the interleaving delay in the previous L0 state. For ADSL, this attribute is derived from the S and D attributes as $\text{cap}(S*D)/4$ ms, where S is the number of symbols per codeword, D is the interleaving depth and cap() denotes rounding to the next higher integer. For [ITU-T G.993.2], this attribute is computed according to the formula in clause 9.7 of [ITU-T G.993.2]. The actual interleaving delay is coded in ms, rounded to the nearest ms. (R) (mandatory) (1 byte) + +**Actual data rate:** This parameter reports the actual net data rate the bearer channel is operating at, excluding the L1 and L2 states. In the L1 or L2 states, the parameter contains the net data rate in the previous L0 state. The data rate is coded in bit/s. (R) (mandatory) (4 bytes) + +**Previous data rate:** This parameter reports the previous net data rate the bearer channel was operating at just before the latest rate change event occurred, excluding transitions between the L0 state and the L1 or L2 states. A rate change can occur at a power management state transition, e.g., at full or short initialization, fast retrain, or power down, or at a dynamic rate adaptation. The rate is coded in bit/s. (R) (mandatory) (4 bytes) + +| | | +|--------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Actual impulse noise protection: | The ACTINP attribute reports the actual impulse noise protection (INP) on the bearer channel in the L0 state. In the L1 or L2 state, the attribute contains the INP in the previous L0 state. For ADSL, this value is computed according to the formula specified in the relevant Recommendation based on the actual framing attributes. For [ITU-T G.993.2], the method to report this value is according to the INPREPORT attribute. The value is coded in fractions of DMT symbols with a granularity of 0.1 symbols. The range is from 0 (0.0 symbols) to 254 (25.4 symbols). The special value 255 indicates an ACTINP higher than 25.4. (R) (mandatory) (1 byte) | +| Impulse noise protection reporting mode: | The INPREPORT attribute reports the method used to compute the ACTINP. If set to 0, the ACTINP is computed according to the INP_no_erasure formula (clause 9.6 of [ITU-T G.993.2]). If set to 1, the ACTINP is the value estimated by the xTU receiver. (R) (mandatory for [ITU-T G.993.2] VDSL2) (1 byte) | +| Actual size of Reed-Solomon codeword: | The NFEC attribute reports the actual Reed-Solomon codeword size used in the latency path in which the bearer channel is transported. Its value is coded in bytes in the range 0..255. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | +| Actual number of Reed-Solomon redundancy bytes: | The RFEC attribute reports the actual number of Reed-Solomon redundancy bytes per codeword used in the latency path in which the bearer channel is transported. Its value is coded in bytes in the range 0..16. The value 0 indicates no Reed-Solomon coding. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | +| Actual number of bits per symbol: | The LSYMB attribute reports the actual number of bits per symbol assigned to the latency path in which the bearer channel is transported, excluding trellis overhead. Its value is coded in bits in the range 0..65535. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (2 bytes) | +| Actual interleaving depth: | The INTLVDEPTH attribute reports the actual depth of the interleaver used in the latency path in which the bearer channel is transported. Its value ranges from 1..4096 in steps of 1. The value 1 indicates no interleaving. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (2 bytes) | +| Actual interleaving block length: | The INTLVBLOCK attribute reports the actual block length of the interleaver used in the latency part in which the bearer channel is transported. Its value ranges from 4..255 in steps of 1. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | +| Actual latency path: | The LPATH attribute reports the index of the actual latency path in which the bearer channel is transported. Valid values are 0..3. In [ITU-T G.992.1], the fast path is mapped to latency index 0; the interleaved path to index 1. (R) (mandatory for [ITU-T G.993.2] VDSL2, optional for others) (1 byte) | + +#### Actions + +#### Get + +#### *Notifications* + +None. + +### **9.7.21 xDSL xTU-C performance monitoring history data** + +This managed entity collects performance monitoring data on the xTU-C to xTU-R path as seen from the xTU-C. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of a physical path termination point xDSL UNI. + +#### *Attributes* + +| | | +|----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL UNI. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Loss of frame seconds: | (R) (mandatory) (2 bytes) | +| Loss of signal seconds: | (R) (mandatory) (2 bytes) | +| Loss of link seconds: | (R) (mandatory) (2 bytes) | +| Loss of power seconds: | (R) (mandatory) (2 bytes) | +| Errored seconds: | This attribute counts one-second intervals with one or more CRC-8 anomalies summed over all received bearer channels, or one or more LOS defects, or one or more SEF defects, or one or more LPR defects. (R) (mandatory) (2 bytes) | +| Severely errored seconds: |

This attribute counts severely errored seconds (SES-L). An SES is declared if, during a one-second interval, there were 18 or more CRC-8 anomalies in one or more of the received bearer channels, or one or more LOS defects, or one or more SEF defects, or one or more LPR defects.

If the relevant Recommendation ([ITU-T G.992.3], [ITU-T G.992.5], [ITU-T G.993.2]) supports a one-second normalized CRC-8 anomaly counter increment, the one-second SES counter follows this value instead of counting CRC-8 anomalies directly.

If a common CRC is applied over multiple bearer channels, then each related CRC-8 anomaly is counted only once for the whole set of bearer channels over which the CRC is applied.

(R) (mandatory) (2 bytes)

| +| Line initializations: | This attribute counts the total number of full initializations attempted on the line, both successful and failed. (R) (mandatory) (2 bytes) | + +- Failed line initializations:** This attribute counts the total number of failed full initializations during the accumulation period. A failed full initialization occurs when showtime is not reached at the end of the full initialization procedure. (R) (mandatory) (2 bytes) +- Short initializations:** This attribute counts the total number of fast retrains or short initializations attempted on the line, successful and failed. Fast retrain is defined in [b-ITU-T G.992.2]. Short initialization is defined in [ITU-T G.992.3] and [ITU-T G.992.4]. (R) (optional) (2 bytes) +- Failed short initializations:** This attribute counts the total number of failed fast retrains or short initializations during the accumulation period, e.g., when: +- A CRC error is detected. + - A timeout occurs. + - A fast retrain profile is unknown. +- (R) (optional) (2 bytes) +- FEC seconds:** This attribute counts seconds during which there was a forward error correction anomaly. (R) (mandatory) (2 bytes) +- Unavailable seconds:** This attribute counts one-second intervals during which the xDSL line is unavailable. The line becomes unavailable at the onset of 10 contiguous SES-Ls. The 10 SES-Ls are included in unavailable time. Once unavailable, the line becomes available at the onset of 10 contiguous seconds that are not severely errored. The 10 seconds with no SES-Ls are excluded from unavailable time. Some attribute counts are inhibited during unavailability – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (mandatory) (2 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +##### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|------------------------------|------------------------------------| +| 0 | Loss of frame seconds | 1 | +| 1 | Loss of signal seconds | 2 | +| 2 | Loss of link seconds | 3 | +| 3 | Loss of power seconds | 4 | +| 4 | Errored seconds | 5 | +| 5 | Severely errored seconds | 6 | +| 6 | Line initializations | 7 | +| 7 | Failed line initializations | 8 | +| 8 | Short initializations | 9 | +| 9 | Failed short initializations | 10 | +| 10 | FEC seconds | 11 | +| 11 | Unavailable seconds | 12 | + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------------------------------------------------------------------------------------------------------------------------------|--------------------------|------------------------------------| +| NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. | | | + +### 9.7.22 xDSL xTU-R performance monitoring history data + +This managed entity collects performance monitoring data of the xTU-C to xTU-R path as seen from the xTU-R. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity is associated with an instance of a physical path termination point xDSL UNI. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL UNI. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Loss of frame seconds:** (R) (mandatory) (2 bytes) +- Loss of signal seconds:** (R) (mandatory) (2 bytes) +- Loss of power seconds:** (R) (mandatory) (2 bytes) +- Errored seconds:** This attribute counts one-second intervals with one or more FEBE anomalies summed over all transmitted bearer channels, or one or more LOS-FE defects, or one or more RDI defects, or one or more LPR-FE defects. (R) (mandatory) (2 bytes) +- Severely errored seconds:** This attribute counts severely errored seconds (SES-LFE). An SES is declared if, during a one-second interval, 18 or more FEBE anomalies were reported across the totality of bearer channels, or there were one or more far-end LOS defects, or one or more RDI defects, or one or more LPR-FE defects. +- If the relevant Recommendation ([ITU-T G.992.3], [ITU-T G.992.5], [ITU-T G.993.2]) supports a one-second normalized CRC-8 anomaly counter increment, the one-second SES counter follows this value instead of counting FEBE anomalies directly. + +If a CRC is applied for multiple bearer channels, then each related FEBE anomaly is counted only once for the whole set of related bearer channels. + +(R) (mandatory) (2 bytes) + +**FEC seconds:** This attribute counts seconds during which there was a forward error correction anomaly. (R) (mandatory) (2 bytes) + +**Unavailable seconds:** This attribute counts one-second intervals during which the far-end xDSL line is unavailable. + +The far-end xDSL line becomes unavailable at the onset of 10 contiguous SES-LFEs. The 10 SES-LFEs are included in unavailable time. Once unavailable, the far-end line becomes available at the onset of 10 contiguous seconds with no SES-LFEs. The 10 seconds with no SES-LFEs are excluded from unavailable time. Some attribute counts are inhibited during unavailability – see clause 7.2.7.13 of [ITU-T G.997.1]. + +(R) (mandatory) (2 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +##### **Get current data (optional)** + +#### *Notifications* + +##### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Loss of frame seconds | 1 | +| 1 | Loss of signal seconds | 2 | +| 2 | Loss of power seconds | 3 | +| 3 | Errored seconds | 4 | +| 4 | Severely errored seconds | 5 | +| 5 | FEC seconds | 6 | +| 6 | Unavailable seconds | 7 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.7.23 xDSL xTU-C channel performance monitoring history data** + +This managed entity collects performance monitoring data of an xTU-C to xTU-R channel as seen from the xTU-C. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity may be associated with each xDSL bearer channel. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The two most significant bits of the first byte are the bearer channel ID. Excluding the first two bits of the first byte, the remaining part of the managed entity ID is identical to that of this ME's parent physical path termination point xDSL UNI part 1. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Corrected blocks:** This attribute counts blocks received with errors that were corrected on this channel. (R) (mandatory) (4 bytes) +- Uncorrected blocks:** This attribute counts blocks received with uncorrectable errors on this channel. (R) (mandatory) (4 bytes) +- Transmitted blocks:** This attribute counts encoded blocks transmitted on this channel. (R) (mandatory) (4 bytes) +- Received blocks:** This attribute counts encoded blocks received on this channel. (R) (mandatory) (4 bytes) +- Code violations:** This attribute counts CRC-8 anomalies in the bearer channel. (R) (mandatory) (2 bytes) +- Forward error corrections:** This attribute counts FEC anomalies in the bearer channel. (R) (mandatory) (2 bytes) + +#### Actions + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|---------------------------|------------------------------------| +| 0 | Corrected blocks | 1 | +| 1 | Uncorrected blocks | 2 | +| 2 | Code violations | 3 | +| 3 | Forward error corrections | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.7.24 xDSL xTU-R channel performance monitoring history data + +This managed entity collects performance monitoring data of the xTU-C to xTU-R channel as seen from the xTU-R. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity may be associated with each xDSL bearer channel. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The two most significant bits of the first byte are the bearer channel ID. Excluding the first two bits of the first byte, the remaining part of the managed entity ID is identical to that of this ME's parent physical path termination point xDSL UNI part 1. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Corrected blocks:** This attribute counts blocks received with errors that were corrected on this channel. (R) (mandatory) (4 bytes) +- Uncorrected blocks:** This attribute counts blocks received with uncorrectable errors on this channel. (R) (mandatory) (4 bytes) +- Transmitted blocks:** This attribute counts encoded blocks transmitted on this channel. (R) (mandatory) (4 bytes) +- Received blocks:** This attribute counts encoded blocks received on this channel. (R) (mandatory) (4 bytes) +- Code violations:** This attribute counts FEBE anomalies reported in the downstream bearer channel. If the CRC is applied over multiple bearer channels, then each related FEBE anomaly increments each of the counters related to the individual bearer channels. (R) (mandatory) (2 bytes) +- Forward error corrections:** This attribute counts FFEC anomalies reported in the downstream bearer channel. If FEC is applied over multiple bearer channels, each related FFEC anomaly increments each of the counters related to the individual bearer channels. (R) (mandatory) (2 bytes) + +#### Actions + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|---------------------------|------------------------------------| +| 0 | Corrected blocks | 1 | +| 1 | Uncorrected blocks | 2 | +| 2 | Code violations | 3 | +| 3 | Forward error corrections | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.7.25 TC adaptor performance monitoring history data xDSL + +This managed entity collects performance monitoring data of an xTU-C to xTU-R ATM data path. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity may be associated with an instance of a physical path termination point xDSL UNI. + +#### *Attributes* + +| | | +|-----------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point xDSL UNI. (R) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Near-end HEC violation count: | This attribute counts near-end HEC anomalies in the ATM data path. (R) (mandatory) (2 bytes) | +| Near-end delineated total cell count (CD-P): | This attribute counts the total number of cells passed through the cell delineation and HEC function process operating on the ATM data path while in the SYNC state. (R) (mandatory) (4 bytes) | +| Near-end user total cell count: | This attribute counts the total number of cells in the ATM data path delivered at the V-C interface. (R) (mandatory) (4 bytes) | +| Near-end idle cell bit error count: | This attribute counts cells with bit errors in the ATM data path idle payload received at the near end. (R) (mandatory) (2 bytes) | +| Far-end HEC violation count: | This attribute counts far-end HEC anomalies in the ATM data path. (R) (mandatory) (2 bytes) | +| Far-end delineated total cell count: | This attribute counts the total number of cells passed through the cell delineation process and HEC function operating on the ATM data path while in the SYNC state. (R) (mandatory) (4 bytes) | +| Far-end user total cell count: | This attribute counts the total number of cells in the ATM data path delivered at the T-R interface. (R) (mandatory) (4 bytes) | +| Far-end idle cell bit error count: | This attribute counts cells with bit errors in the ATM data path idle payload received at the far end. (R) (mandatory) (2 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|------------------------------------|------------------------------------| +| 0 | Near end HEC violation | 1 | +| 1 | Near end idle cell bit error count | 2 | +| 2 | Far end HEC violation count | 3 | +| 3 | Far end idle cell bit error count | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## 9.8 TDM services + +This clause defines managed entities associated with CES UNIs, as shown in Figure 9.8-1. + +![Figure 9.8-1 – Managed entities associated with CES UNIs. This is a block diagram showing the relationships between various managed entities. At the top is '9.8.3: CES service profile-G', pointed to by 'GEM interworking TP'. Below it is '9.8.1: PTP CES UNI', also pointed to by 'GEM interworking TP'. To the left of 9.8.1 is '9.8.2: Logical N x 64 support CTP', pointed to by 'GEM interworking TP', with an arrow pointing to 9.8.1. Below 9.8.1 is '9.8.5: Pseudowire termination point', with an arrow pointing to it from 9.8.2. 9.8.5 has arrows pointing to '9.8.4: CES physical interface PM history data', '9.8.6: RTP pseudowire parameters', '9.8.8: Pseudowire PM history data', and '9.8.7: Pseudowire maintenance profile'. 9.8.5 also has an arrow pointing to '9.8.9: Ethernet flow TP' with labels 'TCP/UDP config data' and 'Large string (FE TP URI)'. 9.8.9 is pointed to by '802.1p mapper service profile' and has 'Implicit links' to 'Extended VLAN tagging operation config data'. Finally, an arrow points from 9.8.9 to 9.8.7 with an 'N' label.](29696d66e33e11fa83d6385ca8712f41_img.jpg) + +Figure 9.8-1 – Managed entities associated with CES UNIs. This is a block diagram showing the relationships between various managed entities. At the top is '9.8.3: CES service profile-G', pointed to by 'GEM interworking TP'. Below it is '9.8.1: PTP CES UNI', also pointed to by 'GEM interworking TP'. To the left of 9.8.1 is '9.8.2: Logical N x 64 support CTP', pointed to by 'GEM interworking TP', with an arrow pointing to 9.8.1. Below 9.8.1 is '9.8.5: Pseudowire termination point', with an arrow pointing to it from 9.8.2. 9.8.5 has arrows pointing to '9.8.4: CES physical interface PM history data', '9.8.6: RTP pseudowire parameters', '9.8.8: Pseudowire PM history data', and '9.8.7: Pseudowire maintenance profile'. 9.8.5 also has an arrow pointing to '9.8.9: Ethernet flow TP' with labels 'TCP/UDP config data' and 'Large string (FE TP URI)'. 9.8.9 is pointed to by '802.1p mapper service profile' and has 'Implicit links' to 'Extended VLAN tagging operation config data'. Finally, an arrow points from 9.8.9 to 9.8.7 with an 'N' label. + +Figure 9.8-1 – Managed entities associated with CES UNIs + +### 9.8.1 Physical path termination point CES UNI + +This managed entity represents the point at a CES UNI in the ONT where the physical path terminates and physical level functions are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has CES ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of CES type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of CES type. Note that the installation of a plug-and-play card may indicate the presence of CES ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies CES ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect a CES circuit pack, nor is it equipped with a CES circuit pack. + +#### Relationships + +An instance of this managed entity is associated with each real or preprovisioned CES port. It can be linked from a pseudowire TP, a logical N x 64 kbit/s CTP, or an interworking TP. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Expected type:** The following coding is used for this attribute: + +| | | +|----------|----------------------------------------------------------------------------------| +| 0 | Autosense. | +| 1 to 254 | One of the values from Table 9.1.5-1 that is compatible with a CES circuit pack. | + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +**Sensed type:** If the value of expected type is not 0, then the value of sensed type equals the value of expected type. If expected type = 0, then the value of sensed type is one of the compatible values from Table 9.1.5-1. Upon ME instantiation, the ONT sets this attribute to 0 or to the value that reflects the physically present equipment. (R) (mandatory if the ONT supports circuit packs with configurable interface types, e.g., C1.5/2/6.3) (1 byte) + +**CES loopback configuration:** This attribute specifies and reports the loopback configuration of the physical interface. + +| | | +|---|-----------------------------------------------------------------------| +| 0 | No loopback. | +| 1 | Payload loopback. | +| 2 | Line loopback. | +| 3 | OpS-directed loopback 1 (loopback from/to PON side). | +| 4 | OpS-directed loopback 2 (loopback from/to CES UNI side). | +| 5 | OpS-directed loopback 3 (loopback of both PON side and CES UNI side). | +| 6 | Manual button-directed loopback (read only). | +| 7 | Network-side code inband-directed loopback (read only). | +| 8 | SmartJack-directed loopback (read only). | +| 9 | Network-side code inband-directed loopback (armed; read only). | + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +![Diagram of CES loopback configuration within an ONT. The ONT contains a PHY framer and a PON interface. Loopback 1 is a loop from the PON interface back to itself. Loopback 2 is a loop from the PHY framer back to itself. Loopback 3 is a loop from the PON interface, through the PHY framer, and back to the PON interface. The CES UNI is connected to the PHY framer, and the PON is connected to the PON interface.](34cf60116177a8f381551d29999491c6_img.jpg) + +``` +graph LR + subgraph ONT + direction LR + PHY[PHY framer] --- PON[PON interface] + PON -- Loopback 1 --> PON + PHY -- Loopback 2 --> PHY + PON -- Loopback 3 --> PHY + end + CES_UNI[CES UNI] --- PHY + PON --- PON_OUT((PON)) +``` + +Diagram of CES loopback configuration within an ONT. The ONT contains a PHY framer and a PON interface. Loopback 1 is a loop from the PON interface back to itself. Loopback 2 is a loop from the PHY framer back to itself. Loopback 3 is a loop from the PON interface, through the PHY framer, and back to the PON interface. The CES UNI is connected to the PHY framer, and the PON is connected to the PON interface. + +Figure 9.8.1-1 – CES loopback configuration + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**DS1 framing:** This attribute specifies the DS1 framing structure. Valid values are: + +- 0 Extended superframe. +- 1 Superframe. +- 2 Unframed. +- 3 G.704. +- 4 JT-G.704. + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory for DS1 interfaces) (1 byte) + +**Encoding:** This attribute specifies the line coding scheme. Valid values are: + +- 0 B8ZS. +- 1 AMI. +- 2 HDB3. +- 3 B3ZS. + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory for DS1 and DS3 interfaces) (1 byte) + +**Line length:** This attribute specifies the length of the twisted pair cable from a DS1 physical UNI to the DSX-1 cross-connect point or the length of coaxial cable from a DS3 physical UNI to the DSX-3 cross-connect point. Valid values are given in Table 9.8.1-1. Upon ME instantiation for a DS1 interface, the ONT assigns the value 0 for non-power feed type DS1 and the value 6 for power feed type DS1. Upon ME instantiation for a DS3 interface, the ONT sets this attribute to 0x0F. (R, W) (optional) (1 byte) + +**DS1 mode:** This attribute specifies the mode of a DS1. Valid values are as shown: + +| Value | Mode | Connect | Line length | Power | Loopback | +|-------|------|-------------|-------------|-----------------|-----------------------------| +| 0 | #1 | DS1 CPE | Short haul | No power feed | Smart jack | +| 1 | #2 | DS1 CPE | Long haul | No power feed | Smart jack | +| 2 | #3 | DS1 NIU CPE | Long haul | No power feed | Intelligent office repeater | +| 3 | #4 | DS1 NIU CPE | Long haul | With power feed | Intelligent office repeater | + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (1 byte) + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +**Line type:** This attribute specifies the line type used in a DS3 or E3 application. Valid values are: + +- 0 Other. +- 1 ds3 m23. +- 2 ds3 syntran. +- 3 ds3 Cbit parity. +- 4 ds3 clear channel. +- 5 e3 framed. +- 6 e3 plc. + +(R, W) (mandatory for DS3 and E3 interfaces, not applicable to other interfaces) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-----------------------------------------------------| +| 1 | N/A | | +| 2 | Sensed type | Sensed circuit pack type (value from Table 9.1.5-1) | +| 3 | CES loopback config | Loopback configuration of physical interface | +| 4 | N/A | | +| 5 | Op state | Operational state | +| 6..9 | N/A | | +| 10 | ARC | ARC timer expiration | +| 11..12 | N/A | | +| 13..16 | Reserved | | + +**Alarm:** These alarms should be declared and cleared according to criteria defined separately in existing TDM standards. + +| Number | Alarm | Description | +|--------|------------|-------------------------------------------| +| 0 | TF | Transmitter failure | +| 1 | LOS | Loss of signal | +| 2 | LOF | Loss of frame | +| 3 | OOF | Out of frame | +| 4 | RAI | Remote alarm indication | +| 5 | 1.5 M BAIS | 1.544 Mbit/s back alarm indication signal | +| 6 | R-INH | Receive alarm inhibit | +| 7 | 6M REC | 6.312 Mbit/s receive alarm | +| 8 | 6M SEND | 6.312 Mbit/s send alarm | +| 9 | 6M ERR | 6.312 Mbit/s block error | + +| Number | Alarm | Description | +|----------|------------------------|----------------------------------------| +| 10 | 6M BERR | 6.312 Mbit/s back error | +| 11 | 34M REC | 34.368 Mbit/s receive alarm | +| 12 | 34M AIS | 34.368 Mbit/s alarm indication signal | +| 13 | 2M REC | 2.048 Mbit/s receive alarm | +| 14 | 2M AIS | 2.048 Mbit/s alarm indication signal | +| 15 | 1.5M REC | 1.544 Mbit/s receive alarm | +| 16 | 1.5 AIS | 1.544 Mbit/s alarm indication signal | +| 17 | INFO0 | INFO0 reception (INFO0) | +| 18 | 45M RDI | 44.736 Mbit/s remote defect indication | +| 19 | 45M AIS | 44.736 Mbit/s alarm indication signal | +| 20..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +**Table 9.8.1-1 – Values for the line length attribute** + +| Value | Power feed | Line length | +|-------|------------------------------------------|------------------------------| +| 0x00 | Non-power feed type DS1 | 0..33.5 m (0..110 ft) | +| 0x01 | Non-power feed type DS1 | 33.5..67.1 m (110..220 ft) | +| 0x02 | Non-power feed type DS1 | 67.1..100.6 m (220..330 ft) | +| 0x03 | Non-power feed type DS1 | 100.6..134.1 m (330..440 ft) | +| 0x04 | Non-power feed type DS1 | 132.1..167.6 m (440..550 ft) | +| 0x05 | Non-power feed type DS1 | 167.6..201.2 m (550..660 ft) | +| 0x06 | Power feed type DS1 (Wet T1), short haul | 0..40.5 m (0..133 ft) | +| 0x07 | Power feed type DS1 (Wet T1), short haul | 40.5..81.1 m (133..266 ft) | +| 0x08 | Power feed type DS1 (Wet T1), short haul | 81.1..121.6 m (266..399 ft) | +| 0x09 | Power feed type DS1 (Wet T1), short haul | 121.6..162.5 m (399..533 ft) | +| 0x0A | Power feed type DS1 (Wet T1), short haul | 162.5..199.6 m (533..655 ft) | +| 0x0B | Power feed type DS1 (Wet T1), long haul | 0 db | +| 0x0C | Power feed type DS1 (Wet T1), long haul | 7.5 db | +| 0x0D | Power feed type DS1 (Wet T1), long haul | 15 db | +| 0x0E | Power feed type DS1 (Wet T1), long haul | 22.5 db | +| 0x0F | DS3 power feed | 0..68.5 m (0..225 ft) | +| 0x10 | DS3 power feed | 68.5..137.1 m (226..450 ft) | + +### 9.8.2 Logical N x 64 kbit/s sub-port connection termination point + +This managed entity models logical sub-ports contained within a higher level TDM physical layer interface (e.g., DS0s within a DS1, DS1s within a DS3, etc.). An instance of this managed entity can represent an arbitrary (i.e., consecutive or non-consecutive) group of multiple channels/time slots (e.g., multiple DS0/DS1) as an integral bundle. + +An instance of this managed entity is created by the OLT before the creation of an associated interworking termination point (see clause 9.2.4, GEM interworking termination point). + +#### Relationships + +Zero or more instances of this ME are associated with an instance of the physical path termination point CES UNI. It can be linked from a pseudowire TP, a logical N x 64 kbit/s CTP, or an interworking TP. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) +- Physical path termination pointer:** This attribute points to the corresponding physical path termination point CES UNI managed entity instance. (R, W, Set-by-create) (mandatory) (2 bytes) +- List of time slots:** This attribute is a bit map that indicates time slots (or component tributaries). Each bit indicates whether the corresponding time slot is included in the connection or not. The correspondence is shown in Figure 9.8.2-1. + +| Byte | Bit | | | | | | | | +|------|-------|-------|-------|-------|-------|-------|-------|-------| +| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| 1 | TS 0 | TS 1 | TS 2 | TS 3 | TS 4 | TS 5 | TS 6 | TS 7 | +| 2 | TS 8 | TS 9 | TS 10 | TS 11 | TS 12 | TS 13 | TS 14 | TS 15 | +| ... | | | | | | | | | +| 12 | TS 88 | TS 89 | TS 90 | TS 91 | TS 92 | TS 93 | TS 94 | TS 95 | + +Figure 9.8.2-1 – Mapping of time slots + +(R, W, Set-by-create) (mandatory) (12 bytes) + +#### Actions + +**Create, delete, get, set** + +#### Notifications + +None. + +### 9.8.3 CES service profile-G + +NOTE – Except for its name, this managed entity is substantially identical to the CES service profileB-PON defined in [ITU-T G.983.2]. + +An instance of this managed entity organizes data that describe the CES service functions of the ONT. Instances of this managed entity are created and deleted by the OLT. + +#### Relationships + +An instance of this managed entity may be associated with zero or more instances of an interworking termination point. + +#### *Attributes* + +| | | +|---------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| CES buffered CDV tolerance: | This attribute represents the duration of user data that must be buffered by the CES interworking entity to offset packet delay variation. It is expressed in 10 microsecond increments. The default value for DS1 CES is 750 µs; for DS3 CES, it is 1000 µs. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Channel associated signalling: | This attribute selects the signalling format. It applies to structured interfaces only. For unstructured interfaces, this value, if present, must be set to the default 0. Valid values are:
0 Basic.
1 E1 CAS.
2 SF CAS.
3 DS1 ESF CAS.
4 J2 CAS.
(R, W, Set-by-create) (optional) (1 byte) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.8.4 CES physical interface performance monitoring history data** + +This managed entity collects statistics for a CES physical interface. Interfaces include DS1, DS3, E1, E3, J1, J2 and possibly others. The performance management requirements of particular interfaces are described in the corresponding ITU-T or other standard document, e.g., [ITU-T G.784]. + +Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with one instance of the physical path termination point CES UNI. + +#### *Attributes* + +| | | +|-------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point CES UNI. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Errored seconds: | (R) (mandatory) (2 bytes) | + +**Severely errored seconds:** (R) (mandatory) (2 bytes) + +**Burst errored seconds:** A burst errored second is any second that is not a UAS, that contains between 2 and 319 error events but no LOS, AIS or OOF condition. (R) (optional) (2 bytes) + +**Unavailable seconds:** (R) (mandatory) (2 bytes) + +**Controlled slip seconds:** (R) (mandatory) (2 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | ES | 1 | +| 1 | SES | 2 | +| 2 | BES | 3 | +| 3 | UAS | 4 | +| 4 | CSS | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.8.5 Pseudowire termination point** + +The pseudowire termination point supports packetized (rather than TDM) G-PON transport of TDM services, transported either directly over Ethernet or over UDP/IP. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +One pseudowire termination point ME exists for each distinct TDM service that is mapped to a pseudowire. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Underlying transport:** 0 Ethernet, MEF8. +1 UDP/IP. +(R, W, Set-by-create) (mandatory) (1 byte) + +**Service type:** This attribute specifies the basic service type, either a transparent bit pipe or an encapsulation that recognizes the underlying structure of the payload. +0 Basic unstructured (also known as structure agnostic). +1 Octet-aligned unstructured, structure agnostic. Applicable only to DS1, a mode in which each frame of 193 bits is encapsulated in 25 bytes with 7 padding bits. +2 Structured (structure-locked). +(R, W, Set-by-create) (mandatory) (1 byte) + +- Signalling:** +- 0 No signalling visible at this layer. + - 1 CAS, to be carried in the same packet stream as the payload. + - 2 CAS, to be carried in a separate signalling channel. +- (R, W, Set-by-create) (mandatory for structured service type) (1 byte) +- TDM UNI pointer:** +- If service type = structured, this attribute points to a logical N x 64 kbit/s sub-port connection termination point. Otherwise, this attribute points to a physical path termination point CES UNI. (R, W, Set-by-create) (mandatory) (2 bytes) +- Near-end IP info:** +- When the pseudowire service is transported via IP, this attribute points to an instance of the TCP/UDP config data managed entity. The default value 0 is applicable if the pseudowire is not transported via IP. (R, W, Set-by-create) (mandatory for IP transport) (2 bytes) +- Far-end IP info:** +- When the pseudowire service is transported via IP, this attribute points to a large string managed entity that contains the URI of the far-end termination point, for example: +- udp://192.168.100.221:5000 or +udp://pwe3srvr.int.example.net:2222 +- The default value 0 is applicable if the pseudowire is not transported via IP. (R, W, Set-by-create) (mandatory for IP transport) (2 bytes) +- Payload size:** +- Number of payload bytes per packet. Valid only if service type = unstructured or unstructured octet-aligned. Valid choices depend on the TDM service, but must include the following. Other choices are at the vendor's discretion. +- DS1 192. + - DS1 200, required only if unstructured octet-aligned service is supported. + - E1 256. + - DS3 1024. + - E3 1024. +- (R, W, Set-by-create) (mandatory for unstructured service) (2 bytes) +- Payload encapsulation delay:** +- Number of 125 microsecond frames to be encapsulated in each pseudowire packet. Valid only if service type = structured. The minimum set of choices for various TDM services is listed below, and is affected by the possible presence of in-band signalling. Other choices are at the vendor's discretion. +- | | | +|--------------------------------|-------------------------------------------| +| NxDS0, no signalling, N = 1 | 64 (8 ms) required,
40 (5 ms) desired. | +| NxDS0, no signalling, N = 2..4 | 32 (4 ms). | +| NxDS0, no signalling, N > 4 | 8 (1 ms). | +| NxDS0 with DS1 CAS | 24 (3 ms). | +| NxDS0 with E1 CAS | 16 (2 ms). | +- (R, W, Set-by-create) (mandatory for structured service) (1 byte) + +| | | +|---------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Timing mode: |

This attribute selects the timing mode of the TDM service. If RTP is used, this attribute must be set to be consistent with the value of the RTP time stamp mode attribute in the RTP parameters managed entity at the far end.

0 Network timing (default).
1 Differential timing.
2 Adaptive timing.
3 Loop timing: local TDM transmit clock derived from local TDM receive stream.

(R, W) (mandatory) (1 byte)

| +| Transmit circuit ID: |

This attribute is a pair of ECID (Ethernet circuit ID) values that the ONT transmits in the direction from the TDM termination toward the packet-switched network. MEF8 ECIDs lie in the range 1..1048575 (2^{20} - 1). To allow for the possibility of other transport (L2TP) in the future, each ECID is allocated 4 bytes.

The first value is used for the payload ECID; the second is used for the optional separate signalling ECID. The first ECID is required for all MEF8 pseudowires; the second is required only if signalling is to be carried in a distinct channel. If signalling is not present, or is carried in the same channel as the payload, the second ECID should be set to 0.

(R, W) (mandatory for MEF8 transport) (8 bytes)

| +| Expected circuit ID: |

This attribute is a pair of ECID (Ethernet circuit ID) values that the ONT can expect in the direction from the packet-switched network toward the TDM termination. Checking ECIDs may be a way to detect circuit misconnection. MEF8 ECIDs lie in the range 1..1048575 (2^{20} - 1). To allow for the possibility of other transport (L2TP) in the future, each ECID is allocated 4 bytes.

The first value is used for the payload ECID; the second is used for the optional separate signalling ECID. In both cases, the default value 0 indicates that no ECID checking is expected.

(R, W) (optional for MEF8 transport) (8 bytes)

| +| Received circuit ID: |

This attribute indicates the actual ECID(s) received on the payload and signalling channels, respectively. It may be used for diagnostic purposes. (R) (optional for MEF8 transport) (8 bytes)

| +| Exception policy: |

This attribute points to an instance of the pseudowire maintenance profile managed entity. If the pointer has its default value 0, the ONT's internal defaults apply. (R, W) (optional) (2 bytes)

| +| ARC: |

See clause I.1.8. (R, W) (optional) (1 byte)

| +| ARC interval: |

See clause I.1.8. (R, W) (optional) (1 byte)

| +| Actions | | +| Create, delete, get, set | | + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------------| +| 1..13 | N/A | | +| 14 | ARC | Alarm reporting control cancellation | +| 15 | N/A | | +| 16 | Reserved | | + +**Alarm:** Alarm criteria may be customized through reference to a pseudowire maintenance profile managed object, or defined by the ONT's internal defaults. + +| Number | Event | Description | +|----------|-------------------------|----------------------------------------------------------------------------------------------------------------| +| 0 | Misconnection | Excessive ratio of stray packets received from the PSN. | +| 1 | Loss of packets | Excessive ratio of lost packets from the PSN. | +| 2 | Buffer overrun | Excessive ratio of packets lost because they arrived from the PSN too early to be buffered for playout. | +| 3 | Buffer underrun | Excessive ratio of packets lost because they arrived from the PSN too late to be buffered for playout. | +| 4 | Malformed packets alarm | Excessive ratio of packets lost because their structure or payload type did not match the provisioned service. | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.8.6 RTP pseudowire parameters + +If a pseudowire service uses RTP, the RTP pseudowire parameters managed entity provides configuration information for the RTP layer. Instances of this managed entity are created and deleted by the OLT. The use of RTP on a pseudowire is optional, and is determined by the existence of the RTP pseudowire parameters managed entity. + +#### Relationships + +An instance of the RTP pseudowire parameters managed entity may exist for each pseudowire termination point managed entity, to which it is implicitly bound by a common managed entity ID. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the pseudowire termination point managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Clock reference:** This attribute specifies the frequency of the common timing reference, in multiples of 8 kHz. The default value is 1 (8 kHz). (R, W, Set-by-create) (mandatory) (2 bytes) + +| | | +|-----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| RTP time stamp mode: | This attribute determines the mode in which RTP timestamps are generated in the TDM to PSN direction.
0 Unknown or not applicable (default).
1 Absolute. Timestamps are based on the timing of the incoming TDM signal.
2 Differential. Timestamps are based on the ONT's reference clock, which is understood to be stratum-traceable along with the reference clock at the far end.
(R, W, Set-by-create) (mandatory) (1 byte) | +| PTYPE: | This attribute specifies the RTP payload type in the TDM to PSN direction. It comprises two values. The first is for the payload channel, the second, for the optional separate signalling channel. Assignable PTYPES lie in the dynamic range 96..127. If signalling is not transported in its own channel, the second value should be set to 0. (R, W, Set-by-create) (mandatory) (2 bytes) | +| SSRC: | This attribute specifies the RTP synchronization source in the TDM to PSN direction. It comprises two values. The first is for the payload channel, the second, for the optional separate signalling channel. If signalling is not transported in its own channel, the second value should be set to 0. (R, W, Set-by-create) (mandatory) (8 bytes) | +| Expected PTYPE: | This attribute specifies the RTP payload type in the PSN to TDM direction. The received payload type may be used to detect malformed packets. It comprises two values. The first is for the payload channel, the second, for the optional separate signalling channel. To disable either or both of the check functions, set the corresponding value to its default value 0. (R, W, Set-by-create) (optional) (2 bytes) | +| Expected SSRC: | This attribute specifies the RTP synchronization source in the PSN to TDM direction. The received SSRC may be used to detect misconnection (stray packets). It comprises two values. The first is for the payload channel, the second, for the optional separate signalling channel. To disable either or both of the check functions, set the corresponding value to its default value 0. (R, W, Set-by-create) (optional) (8 bytes) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.8.7 Pseudowire maintenance profile** + +The pseudowire maintenance profile permits the configuration of pseudowire service exception handling. It is created and deleted by the OLT. + +The settings, and indeed existence, of a pseudowire maintenance profile affect the behaviour of the pseudowire performance monitoring history data managed entity only in establishing criteria for counting severely errored seconds, but in no other way. The pseudowire maintenance profile primarily affects the alarms declared by the subscribing pseudowire termination point. + +#### *Relationships* + +One or more instances of the pseudowire termination point may point to an instance of the pseudowire maintenance profile. If the pseudowire termination point does not refer to a pseudowire maintenance profile, the ONT's default exception handling is implied. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0 is reserved. (R, Set-by-create) (mandatory) (2 bytes) +- Jitter buffer maximum depth:** This attribute specifies the desired maximum depth of the playout buffer in the PSN to TDM direction. The value is expressed as a multiple of the 125 $\mu$ s frame rate. The default value 0 selects the ONT's internal policy. (R, W, Set-by-create) (optional) (2 bytes) +- Jitter buffer desired depth:** This attribute specifies the desired nominal fill depth of the playout buffer in the PSN to TDM direction. The value is expressed as a multiple of the 125 $\mu$ s frame rate. The default value 0 selects the ONT's internal policy. (R, W, Set-by-create) (optional) (2 bytes) +- Fill policy:** This attribute defines the payload bit pattern to be applied toward the TDM service if no payload packet is available to play out. The default value 0 specifies that the ONT apply its internal policy. +- | | | +|---------|----------------------------------------------------------------------------------------------------------| +| 0 | ONT default, vendor-specific (recommended: AIS for unstructured service, all 1s for structured service). | +| 1 | Play out AIS according to the service definition (for example, DS3 AIS). | +| 2 | Play out all 1s. | +| 3 | Play out all 0s. | +| 4 | Repeat the previous data. | +| 5 | Play out DS1 idle (Appendix C of [b-ATIS T1.403]). | +| 6..15 | Reserved for future standardization. | +| 16..255 | Vendor-specific, not to be standardized. | +- (R, W, Set-by-create) (optional) (1 byte) + +Four pairs of alarm-related policy attributes, defined below, share common behaviour. + +The alarm declaration policy attribute defines the anomaly rate that causes the corresponding alarm to be declared. It is an integer percentage between 1..100. If this density of anomalies occurs during the alarm onset soak interval, the alarm is declared. The default value 0 selects the ONT's internal policy. + +The alarm clear policy attribute defines the anomaly rate that causes the corresponding alarm to be cleared. It is an integer percentage between 0..99. If no more than this density of anomalies occurs during the alarm clear soak interval, the alarm is cleared. The default value 255 selects the ONT's internal policy. + +**Misconnected packets declaration policy:** (R, W, Set-by-create) (optional) (1 byte) + +**Misconnected packets clear policy:** (R, W, Set-by-create) (optional) (1 byte) + +**Loss of packets declaration policy:** (R, W, Set-by-create) (optional) (1 byte) + +**Loss of packets clear policy:** (R, W, Set-by-create) (optional) (1 byte) + +| | | +|----------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Buffer overrun/underrun declaration policy: | (R, W, Set-by-create) (optional) (1 byte) | +| Buffer overrun/underrun clear policy: | (R, W, Set-by-create) (optional) (1 byte) | +| Malformed packets declaration policy: | (R, W, Set-by-create) (optional) (1 byte) | +| Malformed packets clear policy: | (R, W, Set-by-create) (optional) (1 byte) | +| R-bit transmit set policy: | This attribute defines the number of consecutive lost packets that causes the transmitted R-bit to be set in the TDM to PSN direction, indicating lost packets to the far end. The default value 0 selects the ONT's internal policy. (R, W, Set-by-create) (optional) (1 byte) | +| R-bit transmit clear policy: | This attribute defines the number of consecutive valid packets that causes the transmitted R-bit to be cleared in the TDM to PSN direction, removing the remote failure indication to the far end. The default value 0 selects the ONT's internal policy. (R, W, Set-by-create) (optional) (1 byte) | +| R-bit receive policy: |

This attribute defines the action toward the N x 64 TDM interface when remote failure is indicated on packets received from the PSN (either R-bit set or M = 0b10 while the L-bit is cleared).

  • 0 Do nothing (default).
  • 1 Play out service-specific RAI/REI/RDI code.
  • 2 Send channel idle signalling and idle channel payload to all DS0s comprising the service.

(R, W, Set-by-create) (optional) (1 byte)

| +| L-bit receive policy: |

This attribute defines the action toward the TDM interface when far end TDM failure is indicated on packets received from the PSN (L-bit set).

  • 0 Play out service-specific AIS (default).
  • 1 Repeat last received packet.
  • 2 Send channel idle signalling and idle channel payload to all DS0s comprising the service.

(R, W, Set-by-create) (optional) (1 byte)

| +| SES threshold: | Number of lost, malformed or otherwise unusable packets expected in the PSN to TDM direction within a one-second interval that causes a severely errored second to be counted. Stray packets do not count toward a severely errored second, nor do packets whose L-bit is set at the far end. The default value is 3. (R, W, Set-by-create) (optional) (2 bytes) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### 9.8.8 Pseudowire performance monitoring history data + +This managed entity collects PM for a pseudowire termination point. Most of the attributes monitor packets received from the PSN, and may therefore be considered egress PM. For the most part, ingress PM is collected at the CES PPTP managed entity. + +NOTE – The pseudowire performance monitoring history data managed entity collects data similar, but not identical, to that available from the MAC bridge port PM history data ME associated with a MAC bridge. When the pseudowire is bridge-based, it may not be necessary to collect both. + +Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the pseudowire termination point. + +#### *Attributes* + +| | | +|-------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the pseudowire termination point. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Received packets: | This attribute counts the total number of packets, both payload and signalling, received in the PSN to TDM direction. (R) (mandatory) (4 bytes) | +| Transmitted packets: | This attribute counts the total number of packets, both payload and signalling, transmitted from the TDM to the PSN. The count includes packets whose L-bit is set and which may therefore contain no payload. (R) (mandatory) (4 bytes) | +| Missing packets: | This attribute counts the number of lost packets, as indicated by gaps in the control word numbering sequence. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) | +| Misordered packets, usable: | This attribute counts the number of packets received out of order, but which were able to be successfully re-ordered and played out. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) | +| Misordered packets dropped: | This attribute counts the number of packets received out of sequence that were discarded, either because the ONT did not support reordering or because it was too late to reorder them. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) | +| Playout buffer underruns/overruns: | This attribute counts the number of packets that were discarded because they arrived too late or too early to be played out. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) | + +- Malformed packets:** This attribute counts the number of malformed packets, for example because the packet length was not as expected or because of unexpected RTP payload type. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Stray packets:** This attribute counts the number of packets whose ECID or RTP SSRC failed to match the expected value, or which are otherwise known to have been misdelivered. Stray packets are discarded without affecting any of the other PM counters. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Remote packet loss:** This attribute counts received packets whose R-bit is set, indicating the loss of packets at the far end. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- TDM L-bit packets transmitted:** This attribute counts the number of packets transmitted with the L-bit set, indicating a near-end TDM fault. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- ES:** This attribute counts errored seconds. Any discarded, lost, malformed or unusable packet received from the PSN during a given second causes this counter to increment. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- SES:** This attribute counts severely errored seconds. The criterion for a SES may be configured through the pseudowire maintenance profile managed entity. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- UAS:** This attribute counts unavailable seconds. An unavailable second begins at the onset of ten consecutive SESs and ends at the onset of ten consecutive seconds that are not severely errored. A service is unavailable if either its payload or its signalling, if any, are unavailable. During unavailable time, only UAS should be counted; other anomalies should not be counted. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|-----------------------------------|------------------------------------| +| 0 | Missing packets | 1 | +| 1 | Misordered packets, usable | 2 | +| 2 | Misordered packets dropped | 3 | +| 3 | Playout buffer underruns/overruns | 4 | +| 4 | Malformed packets | 5 | +| 5 | Stray packets | 6 | + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 6 | Remote packet loss | 7 | +| 7 | ES | 8 | +| 8 | SES | 9 | +| 9 | UAS | 10 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.8.9 Ethernet flow termination point + +The Ethernet flow termination point contains the attributes necessary to originate and terminate Ethernet frames in the ONT. It is appropriate when transporting pseudowire services via layer 2. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +One Ethernet flow termination point ME exists for each distinct pseudowire service that is transported via layer 2. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the ME that is the termination point of its traffic (e.g., a pseudowire termination point managed entity). (R, Set-by-create) (mandatory) (2 bytes) +- Destination MAC:** This attribute specifies the MAC address of the destination Ethernet frames. (R, W, Set-by-create) (mandatory) (6 bytes) +- Source MAC:** This attribute specifies the near-end MAC address. It is established by non-OMCI means (e.g., factory programmed into ONT flash memory) and included here for information only. (R) (mandatory) (6 bytes) +- Tag policy:** This attribute specifies the tagging policy to be applied to upstream Ethernet frames: +0 untagged frame (default). +1 tagged frame. +(R, W, Set-by-create) (mandatory) (1 byte) +- TCI:** If the tag policy calls for tagging of upstream Ethernet frames, this attribute specifies the tag control information, which includes the VLAN tag, P-bits and CFI bit. (R, W) (optional) (2 bytes) +- Loopback:** This attribute sets the loopback configuration: +0 No loopback. +1 Loopback of downstream traffic at MAC client. +(R, W) (mandatory) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.8.10 TU CTP** + +This managed entity organizes data that describes the TU path adaptation processing functions of the ONT for SDH services. Instances of this managed entity are created and deleted at the request of the OLT. + +#### *Relationships* + +One or more instances of this managed entity may be associated with an instance of a physical path termination point CES UNI that supports SDH. + +#### *Attributes* + +**Managed entity id:** This attribute provides a unique number for each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**TU type:** This attribute identifies the TU type. (R, Set-by-create) (mandatory) (1 byte) + +- 1 TU-11. +- 2 TU-12. +- 3 TU-2. +- 4 TU-3. + +**GEM frame loss integration period:** This attribute specifies the GEM frame loss integration period in milliseconds. If GEM frame loss persists for this period, the associated GEM interworking termination point generates a GEM frame starvation alarm. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Transmit J1/J2:** This attribute is the path trace byte string that the ONT transmits upstream. Its default value is null. If set, the ONT inserts a byte of this attribute into the J1 or J2 into each TU payload frame. See [ITU-T G.707] for further information. (R, W, Set-by-create) (mandatory) (16 bytes) + +**Expected J1/J2:** This attribute is the path trace byte string that the ONT expects to receive in the downstream direction. Its default value is null. If set, the ONT compares the J1 or J2 in each received TU payload with this attribute. If the received J1/J2 string differs, a TIM alarm is generated. See [ITU-T G.707] for further information. (R, W, Set-by-create) (mandatory) (16 bytes) + +**Received J1/J2:** This attribute is the actual path trace byte string that the ONT received in the downstream direction. See [ITU-T G.707] for further information. (R) (mandatory) (16 bytes) + +**TIM monitor admin:** This attribute specifies whether or not the TIM (trace indicator mismatch) alarm is monitored. The following code points are defined: + +- 0 Enable. +- 1 Disable. + +Selection of a default value for this attribute is outside the scope of this Recommendation, as it is normally handled through supplier-operator negotiations. (R, W) (mandatory) (1 byte) + +##### **TIM AIS admin:** + +This attribute indicates whether AIS is inserted when a TIM alarm occurs. The following code points are defined: + +- 0 Enable. +- 1 Disable. + +Selection of a default value for this attribute is outside the scope of this Recommendation, as it is normally handled through supplier-operator negotiations. (R, W) (mandatory) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +##### **Alarm** + +| Number | Alarm | Description | +|--------|-----------|--------------------------------------------------------------| +| 0 | TU3-LOP | Loss of pointer alarm of TU3 | +| 1 | TU3-AIS | TU3 alarm indication signal | +| 2 | TU3-LOM | Loss of multiframe indication (H4 mismatch or invalid value) | +| 3 | TU3-UNEQ | TU3 is unequipped with valid data | +| 4 | TU3-SLM | TU3 signal label mismatch | +| 5 | TU3-TIM | Trace indicator in TU3 (J1 mismatch) | +| 6 | TU3-RDI | VC3 alarm indication signal (G1[b5]) | +| 7 | TU3-REI | VC3 remote error indication (G1[b1-b4]) | +| 8 | VC3-SD | VC3 signal degrade | +| 9 | VC3-SF | VC3 signal fail | +| 10 | TU2-LOP | Loss of pointer alarm of TU2 | +| 11 | TU2-AIS | TU2 alarm indication signal | +| 12 | TU2-UNEQ | TU2 is unequipped with valid data | +| 13 | TU2-SLM | TU2 signal label mismatch | +| 14 | TU2-TIM | Trace indicator in TU2 (J2 mismatch) | +| 15 | TU2-RDI | VC2 alarm indication signal (V5[b8]) | +| 16 | TU2-REI | VC2 remote error indication (V5[b3]) | +| 17 | VC2-SD | VC2 signal degrade | +| 18 | VC2-SF | VC2 signal fail | +| 19 | TU12-LOP | Loss of pointer alarm of TU12 | +| 20 | TU12-AIS | TU12 alarm indication signal | +| 21 | TU12-UNEQ | TU12 is unequipped with valid data | +| 22 | TU12-SLM | TU12 signal label mismatch | +| 23 | TU12-TIM | Trace indicator in TU12 (J2 mismatch) | +| 24 | TU12-RDI | VC12 alarm indication signal (V5[b8]) | +| 25 | TU12-REI | VC12 remote error indication (V5[b3]) | +| 26 | VC12-SD | VC12 signal degrade | +| 27 | VC12-SF | VC12 signal fail | +| 28 | TU11-LOP | Loss of pointer alarm of TU11 | + +| Number | Alarm | Description | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|---------------------------------------| +| 29 | TU11-AIS | TU11 alarm indication signal | +| 30 | TU11-UNEQ | TU11 is unequipped with valid data | +| 31 | TU11-SLM | TU11 signal label mismatch | +| 32 | TU11-TIM | Trace indicator in TU11 (J2 mismatch) | +| 33 | TU11-RDI | VC11 alarm indication signal (V5[b8]) | +| 34 | TU11-REI | VC11 remote error indication (V5[b3]) | +| 35 | VC11-SD | VC11 signal degrade | +| 36 | VC11-SF | VC11 signal fail | +| NOTE – When the received frame BER of VCn becomes $\geq 10^{-x}$ , the VCn-SD, VCn-SF state is entered. The threshold X of VCn-SD and VCn-SF reuses the SD, SF threshold of the GEM frame. | | | + +### 9.8.11 TU performance monitoring history data + +This managed entity collects performance monitoring data from SDH TUs. Most of the parameters are received from the GEM layer, and may therefore be considered egress PM. For the most part, ingress PM is collected at the CES managed entity. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +One instance of this managed entity may exist for each instance of the TU CTP managed entity. + +#### *Attributes* + +| | | +|-------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of a TU CTP. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Positive pointer justification: | This attribute counts pointer increments generated. (R) (mandatory) (4 bytes) | +| Negative pointer justification: | This attribute counts pointer decrements generated. (R) (mandatory) (4 bytes) | +| Near-end block error seconds: | This attribute counts near-end block errored seconds. (R) (mandatory) (4 bytes) | +| Near-end severely block error seconds: | This attribute counts near-end severely block errored seconds. (R) (mandatory) (4 bytes) | +| Remote-end block error seconds: | This attribute counts far-end block errored seconds. (R) (mandatory) (4 bytes) | +| Remote-end severely block error seconds: | This attribute counts far-end severely block errored seconds. (R) (mandatory) (4 bytes) | + +| | | +|-------------------------------------------|-----------------------------------------------------------------------------------| +| Near-end background block error: | This attribute counts near-end background block errors. (R) (mandatory) (4 bytes) | +| Remote-end background block error: | This attribute counts far-end background block errors. (R) (mandatory) (4 bytes) | +| Near-end unavailable seconds: | This attribute counts near-end unavailable seconds. (R) (mandatory) (4 bytes) | +| Remote-end unavailable seconds: | This attribute counts far-end unavailable seconds. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|-----------------------------------------|------------------------------------| +| 0 | Positive pointer justification | 1 | +| 1 | Negative pointer justification | 2 | +| 2 | Near-end block error seconds | 3 | +| 3 | Near-end severely block error seconds | 4 | +| 4 | Remote-end block error seconds | 5 | +| 5 | Remote-end severely block error seconds | 6 | +| 6 | Near-end background block error | 7 | +| 7 | Remote-end background block error | 8 | +| 8 | Near-end unavailable seconds | 9 | +| 9 | Remote-end unavailable seconds | 10 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## 9.9 Voice services + +This clause defines managed entities associated with POTS (VoIP) service, as shown in Figure 9.9-1. + +![Figure 9.9-1: Managed entities associated with POTS (VoIP) service. This is a hierarchical diagram showing relationships between various managed entities. At the top are 9.9.12 (Call control PM history data), 9.9.11 (VoIP line status), and 9.9.13 (RTP PM history data). 9.9.12 and 9.9.11 point to 9.9.1 (PPTP POTS UNI / PPTP ISDN UNI). 9.9.13 also points to 9.9.1. 9.9.1 points to 'GEM interworking TP'. 9.9.4 (VoIP voice CTP) points to 9.9.1 and 9.9.2 (SIP user data). 9.9.2 points to 9.9.10 (Network dial plan table), 'Authentication security method Large string (AoR) Network address', 9.9.8 (VoIP application service profile), and 9.9.3 (SIP agent config data). 9.9.8 points to '(3x) Network address'. 9.9.3 points to '(3x) Large string Network address TCP/UDP config data'. 9.9.15 (SIP call initiation PM history data) and 9.9.14 (SIP agent PM history data) both point to 9.9.3. 9.9.4 also points to 9.9.5 (VoIP media profile), 9.9.9 (VoIP feature access codes), and 9.9.16 (MGC config data). 9.9.5 points to 9.9.7 (RTP profile data) and 9.9.6 (Voice service profile). 9.9.16 points to '(2x) Network address TCP/UDP config data'. 9.9.17 (MGC PM history data) points to 9.9.16. 9.9.19 (SIP config portal) and 9.9.20 (MGC config portal) both point to 9.9.16. 9.9.18 (VoIP config data) points to 'Network address'.](d22a6b8548de8278dc3f686e95f9f47b_img.jpg) + +``` + +graph TD + 9.9.12[9.9.12: Call control PM history data] -.-> 9.9.1[9.9.1: PPTP POTS UNI +9.9.21: PPTP ISDN UNI] + 9.9.11[9.9.11: VoIP line status] -.-> 9.9.1 + 9.9.13[9.9.13: RTP PM history data] -.-> 9.9.1 + 9.9.1 --> GEM[GEM interworking TP] + 9.9.4[9.9.4: VoIP voice CTP] --> 9.9.1 + 9.9.4 --> 9.9.2[9.9.2: SIP user data] + 9.9.4 --> 9.9.5[9.9.5: VoIP media profile] + 9.9.4 --> 9.9.9[9.9.9: VoIP feature access codes] + 9.9.4 --> 9.9.16[9.9.16: MGC config data] + 9.9.2 --> 9.9.10[9.9.10: Network dial plan table] + 9.9.2 --> Auth[Authentication security method +Large string (AoR) +Network address] + 9.9.2 --> 9.9.8[9.9.8: VoIP application service profile] + 9.9.2 --> 9.9.3[9.9.3: SIP agent config data] + 9.9.8 --> NA3[(3x) Network address] + 9.9.3 --> NA3L[(3x) Large string +Network address +TCP/UDP config data] + 9.9.15[9.9.15: SIP call initiation PM history data] -.-> 9.9.3 + 9.9.14[9.9.14: SIP agent PM history data] -.-> 9.9.3 + 9.9.5 --> 9.9.7[9.9.7: RTP profile data] + 9.9.5 --> 9.9.6[9.9.6: Voice service profile] + 9.9.16 --> NA2[(2x) Network address +TCP/UDP config data] + 9.9.17[9.9.17: MGC PM history data] -.-> 9.9.16 + 9.9.19[9.9.19: SIP config portal +9.9.20: MGC config portal] --> 9.9.16 + 9.9.18[9.9.18: VoIP config data] --> NA1[Network address] + +``` + +Figure 9.9-1: Managed entities associated with POTS (VoIP) service. This is a hierarchical diagram showing relationships between various managed entities. At the top are 9.9.12 (Call control PM history data), 9.9.11 (VoIP line status), and 9.9.13 (RTP PM history data). 9.9.12 and 9.9.11 point to 9.9.1 (PPTP POTS UNI / PPTP ISDN UNI). 9.9.13 also points to 9.9.1. 9.9.1 points to 'GEM interworking TP'. 9.9.4 (VoIP voice CTP) points to 9.9.1 and 9.9.2 (SIP user data). 9.9.2 points to 9.9.10 (Network dial plan table), 'Authentication security method Large string (AoR) Network address', 9.9.8 (VoIP application service profile), and 9.9.3 (SIP agent config data). 9.9.8 points to '(3x) Network address'. 9.9.3 points to '(3x) Large string Network address TCP/UDP config data'. 9.9.15 (SIP call initiation PM history data) and 9.9.14 (SIP agent PM history data) both point to 9.9.3. 9.9.4 also points to 9.9.5 (VoIP media profile), 9.9.9 (VoIP feature access codes), and 9.9.16 (MGC config data). 9.9.5 points to 9.9.7 (RTP profile data) and 9.9.6 (Voice service profile). 9.9.16 points to '(2x) Network address TCP/UDP config data'. 9.9.17 (MGC PM history data) points to 9.9.16. 9.9.19 (SIP config portal) and 9.9.20 (MGC config portal) both point to 9.9.16. 9.9.18 (VoIP config data) points to 'Network address'. + +Figure 9.9-1 – Managed entities associated with POTS (VoIP) service + +### 9.9.1 Physical path termination point POTS UNI + +This managed entity represents the point at a POTS UNI in the ONT where a physical path terminates and physical path level functions (analogue telephony) are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has POTS ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of POTS type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of POTS type. Note that the installation of a plug-and-play card may indicate the presence of POTS ports via equipment ID as well as type, and indeed may cause the ONT to instantiate a port mapping package that specifies POTS ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect a POTS circuit pack, nor is it equipped with a POTS circuit pack. + +#### Relationships + +An instance of this managed entity is associated with each real or preprovisioned POTS port. SIP and VoIP voice CTPs may link to the POTS UNI, which in turn points to a GEM interworking TP. Status is available from a VoIP line status ME, and RTP and call control PM may be collected on this point. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). If the UNI is integrated, this value is 0. The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Interworking TP pointer:** This attribute points to the associated instance of the GEM interworking termination point managed entity. The value 0 is a null pointer. (R, W) (optional) (2 bytes) + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +**Impedance:** This attribute specifies the impedance for the POTS UNI. Valid values include: + +- 0 600 Ohms. +- 1 900 Ohms. + +The following parameter sets from Annex C of [ETSI TS 101 270-1] are also defined: + +- 2 C1=150 nF, R1=750 Ohm, R2=270 Ohm. +- 3 C1=115 nF, R1=820 Ohm, R2=220 Ohm. +- 4 C1=230 nF, R1=1050 Ohm, R2=320 Ohm. + +Where C1, R1, and R2 are related as shown in Figure 9.9.1-1. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (1 byte) + +![Circuit diagram of the impedance model for POTS UNI. It shows a parallel combination of a capacitor C1 and a resistor R1, which is then in series with a resistor R2.](893d579aad08ea146a5358bb0218d207_img.jpg) + +The diagram shows an electrical circuit model. On the left, there is a parallel combination of a capacitor labeled C1 and a resistor labeled R1. This parallel block is connected in series with a resistor labeled R2. The circuit has input and output terminals on the left and right respectively. + +Circuit diagram of the impedance model for POTS UNI. It shows a parallel combination of a capacitor C1 and a resistor R1, which is then in series with a resistor R2. + +**Figure 9.9.1-1 – Impedance model for POTS UNI** + +**Transmission path:** This attribute allows setting the POTS UNI either to full-time on-hook transmission (0) or part-time on-hook transmission (1). Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (1 byte) + +**Rx gain:** This attribute specifies a gain value for the received signal in the form of a 2s complement number. Valid values are -120 (-12.0 dB) to 60 (+6.0 dB). Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (1 byte) + +**Tx gain:** This attribute specifies a gain value for the transmit signal in the form of a 2s complement number. Valid values are -120 (-12.0 dB) to 60 (+6.0 dB). Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (1 byte) + +**Operational state:** This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Hook state:** This attribute indicates the current state of the subscriber line: 0 = on hook, 1 = off hook. (R) (Optional) (1 byte) + +**POTS holdover time:** This attribute determines the time during which POTS loop voltage is held up when the ONT is not ranged on the PON. After the specified time elapses, the ONT drops loop voltage, and may thereby cause premises intrusion alarm circuits to go active. When the ONT ranges successfully on the PON, it restores POTS loop voltage immediately and resets the timer to zero. The attribute is expressed in seconds. The default value 0 selects the vendor's factory policy. (R, W) (optional) (2 bytes) + +#### *Actions* + +#### **Get, set** + +**Test:** Request that the ONT perform one or more MLT tests or a dial tone make/break test. Vendor-specific tests are also supported by the test and test result message layouts in clauses II.2.27 and II.2.45. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------| +| 1..2 | N/A | | +| 3 | ARC | ARC timer expiration | +| 4..8 | N/A | | +| 9 | Op state | Operational state | +| 10..11 | N/A | | +| 12..16 | Reserved | | + +### 9.9.2 SIP user data + +The SIP user data defines the user-specific configuration attributes associated with a specific VoIP CTP. This entity is conditionally required for ONTs that offer VoIP SIP services. If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +An instance of this managed entity is created and deleted by the OLT. A SIP user data instance is required for each POTS UNI port using SIP protocol and configured by OMCI. + +#### *Relationships* + +An instance of this managed entity is associated with one VoIP voice CTP managed entity and a PTP POTS UNI. + +#### *Attributes* + +| | | +|------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| SIP agent pointer: | This attribute points to the SIP agent config data ME to be used for signalling. (R, W, Set-by-create) (mandatory) (2 bytes) | +| User part AOR: | This attribute points to a large string that contains the user identification part of the address of record. This can take the form of an alphanumeric string or the subscriber's directory number. The value 0xFFFF is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | +| SIP display name: | This ASCII string attribute defines the customer id used for the display attribute in outgoing SIP messages. The default value is null (all zero bytes). (R, W) (mandatory) (25 bytes) | +| Username/password: | This attribute points to an authentication security method ME that contains the SIP user name and password used for authentication. 0xFFFF indicates no username/password. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Voicemail server SIP URI: | This attribute points to a network address ME that contains the name (IP address or URI) of the SIP voicemail server for SIP signalling messages. The default value 0xFFFF is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Voicemail subscription expiration time: | This attribute defines the voicemail subscription expiration time in seconds. If this value is 0, the SIP agent uses an implementation-specific value. The default value of this attribute is 3600 seconds. (R, W, Set-by-create) (mandatory) (4 bytes) | +| Network dial plan pointer: | This attribute points to a network dial plan table. The default value 0xFFFF is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Application services profile pointer: | This attribute points to a VoIP application services profile. The default value 0xFFFF is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Feature code pointer: | This attribute points to the VoIP feature access codes ME for this subscriber. The default value 0xFFFF is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | + +- PPTP pointer:** This attribute points to the PPTP POTS UNI managed entity that provides the analogue telephony adaptor (ATA) function. The default value 0xFFFF is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) +- Release timer:** This attribute contains a release timer defined in seconds. The value 0 specifies that the ONT is to use its internal default. The default value of this attribute is 10 seconds. (R, W) (optional) (1 byte) +- ROH timer:** This attribute defines the time in seconds for the receiver off hook condition before ROH tone is applied. The value 0 disables ROH timing. The default value is 15 seconds. (R, W) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +##### *Notifications* + +##### **Alarm** + +| Number | Alarm | Description | +|----------|------------------------|----------------------------------------------------------------------| +| 0 | SIPUA register auth | Cannot authenticate registration session (e.g., missing credentials) | +| 1 | SIPUA register timeout | Timeout waiting for response from registration server | +| 2 | SIPUA register fail | Failure response received from registration server | +| 3..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.9.3 SIP agent config data** + +The SIP agent config data managed entity models a SIP signalling agent. It defines the configuration necessary to establish communication for signalling between the SIP user agent and a SIP server. + +NOTE – If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity serves one or more SIP user data managed entities and points to a TCP/UDP config data that carries signalling messages. Other pointers establish additional agent parameters such as proxy servers. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) +- Proxy server address pointer:** This attribute points to a large string ME that contains the name (IP address or URI) of the SIP proxy server for SIP signalling messages. (R, W, Set-by-create) (mandatory) (2 bytes) + +| | | +|----------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Outbound proxy address pointer: | This attribute points to a large string ME that contains the name (IP address or URI) of the outbound proxy server for SIP signalling messages. An outbound SIP proxy may or may not be required within a given network. If an outbound SIP proxy is used, the outbound proxy address pointer attribute must be set to point to a valid large string ME. If an outbound SIP proxy is not used, the outbound proxy address pointer attribute must be set to a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Primary SIP DNS: | This attribute specifies the primary SIP DNS IP address. If this value is 0, no primary SIP DNS is defined. The default value is 0. (R, W, Set-by-create) (mandatory) (4 bytes) | +| Secondary SIP DNS: | This attribute specifies the secondary SIP DNS IP address. If this value is 0, no secondary SIP DNS is defined. The default value is 0. (R, W, Set-by-create) (mandatory) (4 bytes) | +| TCP/UDP pointer: | This pointer associates the SIP agent with the TCP/UDP config data ME to be used for communication with the SIP server. The default value is 0xFFFF. (R, W) (mandatory) (2 bytes) | +| SIP reg exp time: | This attribute specifies the SIP registration expiration time in seconds. If its value is 0, the SIP agent does not add an expiration time to the registration requests and does not perform re-registration. The default value is 3600 seconds. (R, W) (mandatory) (4 bytes) | +| SIP rereg head start time: | This attribute specifies the time in seconds prior to timeout that causes the SIP agent to start the re-registration process. The default value is 360 seconds. (R, W) (mandatory) (4 bytes) | +| Host part URI: | This attribute points to a large string ME that contains the host or domain part of the SIP address of record for users connected to this ONT. The default value 0xFFFF indicates that the current address in the IP host config ME is used. (R, W, Set-by-create) (mandatory) (2 bytes) | +| SIP status: |

This attribute shows the current status of the SIP agent. Values are as follows:

  • 0 Ok/initial.
  • 1 Connected.
  • 2 Failed – ICMP error.
  • 3 Failed – Malformed response.
  • 4 Failed – Inadequate info response.
  • 5 Failed – Timeout.

(R) (mandatory) (1 byte)

| +| SIP registrar: | This attribute points to a network address ME that contains the name (IP address or resolved name) of the registrar server for SIP signalling messages. Examples: "10.10.10.10" and "proxy.voip.net". The default value is 0xFFFF. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Softswitch: | This attribute identifies the SIP gateway softswitch vendor. The format is four ASCII coded alphabetic characters [A..Z] as defined in [ATIS-0322000]. A value of four null characters indicates no particular vendor. (R, W, Set-by-create) (mandatory) (4 bytes) | + +#### Actions + +##### Create, delete, get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|---------------| +| 1..8 | N/A | | +| 9 | SIP status | Status change | +| 10..11 | N/A | | +| 12..16 | Reserved | | + +##### Alarm + +| Number | Alarm | Description | +|----------|-------------------------|--------------------------------------------------------------------------------------------------------| +| 0 | SIPUA register name | Failed to resolve the registration server name | +| 1 | SIPUA register reach | Cannot reach registration server (the port cannot be reached, ICMP errors) | +| 2 | SIPUA register connect | Cannot connect to registration server (due to bad credentials or other fault after the port responded) | +| 3 | SIPUA register validate | Cannot validate registration server | +| 4 (Note) | SIPUA register auth | Cannot authenticate registration session (e.g., missing credentials) | +| 5 (Note) | SIPUA register timeout | Timeout waiting for response from registration server | +| 6 (Note) | SIPUA register fail | Failure response received from registration server | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +NOTE – These alarms are deprecated, and retained for backward compatibility. It is recommended that the SIP agent config data not declare these alarms, but that they be declared by the SIP user data ME instead. In any event, only one ME should declare the alarm, not both. + +### 9.9.4 VoIP voice CTP + +The VoIP voice CTP defines the attributes necessary to associate a specified VoIP service (SIP (e.g., [b-IETF RFC 3261]), [ITU-T H.248.x]) with a POTS UNI. This entity is conditionally required for ONTs that offer VoIP services. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME or the MGC config portal ME. + +An instance of this managed entity is created and deleted by the OLT. A VoIP voice CTP managed object is needed for each PTP POTS UNI served by VoIP. + +#### Relationships + +An instance of this managed entity links a PTP POTS managed entity with a VoIP media profile and a SIP user data or MGC config data ME. + +#### *Attributes* + +| | | +|------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| User protocol pointer: | This attribute points to signalling protocol data. If the VoIP config data specifies that the ONT's signalling protocol is SIP, this attribute points to a SIP user data ME, which in turn points to a SIP agent config data. If the signalling protocol is H.248, this attribute points directly to an MGC config data ME. (R, W, Set-by-create) (mandatory) (2 bytes) | +| PPTP pointer: | This attribute points to the PPTP POTS UNI managed entity that serves the analogue telephone port. (R, W, Set-by-create) (mandatory) (2 bytes) | +| VoIP media profile pointer: | This attribute points to an associated VoIP media profile. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Signalling code: | This attribute specifies the POTS-side signalling:
  1. 1 Loop start.
  2. 2 Ground start.
  3. 3 Loop reverse battery.
  4. 4 Coin first.
  5. 5 Dial tone first.
  6. 6 Multi-party.
(R, W, Set-by-create) (mandatory) (1 byte) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.9.5 VoIP media profile** + +The VoIP media profile managed entity contains settings that apply to VoIP voice encoding. This entity is conditionally required for ONTs that offer VoIP services. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME or the MGC config portal ME. + +An instance of this managed entity is created and deleted by the OLT. A VoIP media profile is needed for each unique set of profile attributes. + +#### *Relationships* + +An instance of this managed entity may be associated with one or more VoIP voice CTP managed entities. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Fax mode:** Selects the fax mode; values are: + +- 0 Passthru. +- 1 T.38. + +The default value is 0. (R, W, Set-by-create) (mandatory) (1 byte) + +**Voice service profile pointer:** Pointer to a voice service profile. This ME defines jitter, echo cancellation and PSTN data. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Codec selection (1st order):** This attribute specifies codec selection as defined by [IETF RFC 3551]. The default value is 0, PCMU. + +| Value | Encoding name | Clock rate (Hz) | +|-------|-----------------|-----------------| +| 0 | PCMU | 8,000 | +| 1 | Reserved | | +| 2 | Reserved | | +| 3 | GSM | 8,000 | +| 4 | G723 | 8,000 | +| 5 | DVI4 | 8,000 | +| 6 | DVI4 | 16,000 | +| 7 | LPC | 8,000 | +| 8 | PCMA | 8,000 | +| 9 | G722 | 8,000 | +| 10 | L16, 2 channels | 44,100 | +| 11 | L16, 1 channel | 44,100 | +| 12 | QCELP | 8,000 | +| 13 | CN | 8,000 | +| 14 | MPA | 90,000 | +| 15 | G728 | 8,000 | +| 16 | DVI4 | 11,025 | +| 17 | DVI4 | 22,050 | +| 18 | G729 | 8,000 | + +(R, W, Set-by-create) (mandatory) (1 byte) + +**Packet period selection (1st order):** This attribute specifies the packet period selection interval in milliseconds. The default value is 10. Valid values are 10..30 ms. (R, W, Set-by-create) (mandatory) (1 byte) + +**Silence suppression (1st order):** This attribute specifies whether silence suppression is on or off. Valid values are 0 = off and 1 = on. (R, W, Set-by-create) (mandatory) (1 byte) + +Three more groups of three attributes are defined, with definitions identical to the preceding three: + +**Codec selection (2nd order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Packet period selection (2nd order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Silence suppression (2nd order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Codec selection (3rd order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Packet period selection (3rd order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Silence suppression (3rd order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Codec selection (4th order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Packet period selection (4th order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**Silence suppression (4th order):** (R, W, Set-by-create) (mandatory) (1 byte) + +**OOB DTMF:** This attribute specifies out-of-band DMTF carriage. When enabled (1), DTMF signals are carried out of band via RTP or the associated signalling protocol. When disabled, DTMF tones are carried in the PCM stream. (R, W, Set-by-create) (mandatory) (1 byte) + +**RTP profile pointer:** This attribute points to the associated RTP profile data ME. (R, W, Set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.9.6 Voice service profile** + +NOTE – Except for the change of name, this managed entity is substantially identical to the voice service profile AAL managed entity defined in [ITU-T G.983.2]. + +This managed entity organizes data that describes the voice service functions of the ONT. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with zero or more instances of a VoIP voice CTP by way of a VoIP media profile. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Announcement type:** This attribute specifies the treatment when a subscriber goes off hook but does not attempt a call. Valid values include: + +| | | +|------|---------------------| +| 0x01 | Silence. | +| 0x02 | Reorder tone. | +| 0x03 | Fast busy. | +| 0x04 | Voice announcement. | +| 0xFF | N/A. | + +(R, W, Set-by-create) (mandatory) (1 byte) + +| | | +|-------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Jitter target: | This attribute specifies the target value of the jitter buffer in milliseconds. The system tries to maintain the jitter buffer at the target value. (R, W, Set-by-create) (optional) (2 bytes) | +| Jitter buffer max: | This attribute specifies the maximum depth of the jitter buffer associated with this service in milliseconds. (R, W, Set-by-create) (optional) (2 bytes) | +| Echo cancel ind: | The Boolean value true specifies that echo cancellation is on; false specifies off. (R, W, Set-by-create) (mandatory) (1 byte) | +| PSTN protocol variant: | This attribute controls which variant of POTS signalling is used on the associated UNIs. Its value is equal to the E.164 country code. (R, W, Set-by-create) (optional) (2 bytes) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.9.7 RTP profile data** + +This managed entity configures RTP. It is conditionally required for ONTs that offer VoIP service. If a non-OMCI interface is used to manage VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal or the MGC config portal ME. + +An instance of this managed entity is created and deleted by the OLT. An RTP profile is needed for each unique set of attributes. + +#### *Relationships* + +An instance of this managed entity may be associated with one or more VoIP media profile managed entities. + +#### *Attributes* + +| | | +|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| Local port min: | This attribute defines the base RTP port that should be used for voice traffic. The default is 50000. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Local port max: | This attribute defines the highest RTP port used for voice traffic. The default must be greater than local port min but is determined by vendor application. (R, W, Set-by-create) (optional) (2 bytes) | +| DSCP mark: | Diffserv code point to be used for outgoing RTP packets for this profile. The default value is expedited forwarding (EF) = 0x2E. (R, W, Set-by-create) (mandatory) (1 byte) | +| Piggyback events: | Enables or disables RTP piggyback events.
0 Disabled (default).
1 Enabled.
(R, W, Set-by-create) (mandatory) (1 byte) | + +- Tone events:** Enables or disables handling of tones via RTP tone events per [IETF RFC 4733] (see also [IETF RFC 4734]). +- 0 Disabled (default). + - 1 Enabled. +- (R, W, Set-by-create) (mandatory) (1 byte) +- DTMF events:** Enables or disables handling of DTMF via RTP DTMF events per [IETF RFC 4733] (see also [IETF RFC 4734]). This attribute is ignored unless the OOB DTMF attribute in the VoIP media profile is enabled. +- 0 Disabled (default). + - 1 Enabled. +- (R, W, Set-by-create) (mandatory) (1 byte) +- CAS events:** Enables or disables handling of CAS via RTP CAS events per [IETF RFC 4733] (see also [IETF RFC 4734]). +- 0 Disabled (default). + - 1 Enabled. +- (R, W, Set-by-create) (mandatory) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.9.8 VoIP application service profile** + +The VoIP application service profile defines attributes of calling features used in conjunction with a VoIP line service. It is optional for ONTs that support VoIP service. If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +An instance of this managed entity is created and deleted by the OLT. A VoIP application service managed object is needed for each unique set of profile attributes. + +#### *Relationships* + +An instance of this managed entity is associated with zero or more SIP user data MEs. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. +(R, Set-by-create) (mandatory) (2 bytes) + +| | | | | | | | | | | | | | | | | | | | | +|--------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------------------------------------|--------|----------------------------------------------|------------|----------------------------------------------|--------|------------------------------------------------------------------------------------|----------------|--------------------------------------------------------------------------------|--------|---------------------------------------------------------------------------------------------|------------|--------------------------------------------------------------------------------------------------------------------------------------|--------|------|----------------|----------| +| CID features: |

This attribute contains a bit map of caller ID features. Except as noted, the value 0 disables the feature; 1 enables it.

0x01Calling number
0x02Calling name
0x04CID blocking (both number and name)
0x08CID number – Permanent presentation status for number
(0 = public, 1 = private)
0x10CID name – Permanent presentation status for name
(0 = public, 1 = private)
0x20Anonymous CID blocking (ACR). It may not be possible to support this in the ONT.
0x40..0x80Not used

The default value is disabled. (R, W, Set-by-create) (mandatory) (1 byte)

| 0x01 | Calling number | 0x02 | Calling name | 0x04 | CID blocking (both number and name) | 0x08 | CID number – Permanent presentation status for number
(0 = public, 1 = private) | 0x10 | CID name – Permanent presentation status for name
(0 = public, 1 = private) | 0x20 | Anonymous CID blocking (ACR). It may not be possible to support this in the ONT. | 0x40..0x80 | Not used | | | | | +| 0x01 | Calling number | | | | | | | | | | | | | | | | | | | +| 0x02 | Calling name | | | | | | | | | | | | | | | | | | | +| 0x04 | CID blocking (both number and name) | | | | | | | | | | | | | | | | | | | +| 0x08 | CID number – Permanent presentation status for number
(0 = public, 1 = private) | | | | | | | | | | | | | | | | | | | +| 0x10 | CID name – Permanent presentation status for name
(0 = public, 1 = private) | | | | | | | | | | | | | | | | | | | +| 0x20 | Anonymous CID blocking (ACR). It may not be possible to support this in the ONT. | | | | | | | | | | | | | | | | | | | +| 0x40..0x80 | Not used | | | | | | | | | | | | | | | | | | | +| Call waiting features: |

This attribute contains a bit map of call waiting features. The value 0 disables the feature; 1 enables it.

0x01Call waiting
0x02Caller ID announcement
0x04..0x80Not used

The default value is disabled. (R, W, Set-by-create) (mandatory) (1 byte)

| 0x01 | Call waiting | 0x02 | Caller ID announcement | 0x04..0x80 | Not used | | | | | | | | | | | | | +| 0x01 | Call waiting | | | | | | | | | | | | | | | | | | | +| 0x02 | Caller ID announcement | | | | | | | | | | | | | | | | | | | +| 0x04..0x80 | Not used | | | | | | | | | | | | | | | | | | | +| Call progress or transfer features: |

This attribute is a bit map of call processing features. The value 0 disables the feature; 1 enables it.

0x00013way
0x0002Call transfer
0x0004Call hold
0x0008Call park
0x0010Do not disturb
0x0020Flash on emergency service call (flash is to be processed during an emergency service call)
0x0040Emergency service originating hold (determines whether call clearing is to be performed on on-hook during an emergency service call)
0x00806way
0x0100..0x8000Not used

The default value is disabled. (R, W, Set-by-create) (mandatory) (2 bytes)

| 0x0001 | 3way | 0x0002 | Call transfer | 0x0004 | Call hold | 0x0008 | Call park | 0x0010 | Do not disturb | 0x0020 | Flash on emergency service call (flash is to be processed during an emergency service call) | 0x0040 | Emergency service originating hold (determines whether call clearing is to be performed on on-hook during an emergency service call) | 0x0080 | 6way | 0x0100..0x8000 | Not used | +| 0x0001 | 3way | | | | | | | | | | | | | | | | | | | +| 0x0002 | Call transfer | | | | | | | | | | | | | | | | | | | +| 0x0004 | Call hold | | | | | | | | | | | | | | | | | | | +| 0x0008 | Call park | | | | | | | | | | | | | | | | | | | +| 0x0010 | Do not disturb | | | | | | | | | | | | | | | | | | | +| 0x0020 | Flash on emergency service call (flash is to be processed during an emergency service call) | | | | | | | | | | | | | | | | | | | +| 0x0040 | Emergency service originating hold (determines whether call clearing is to be performed on on-hook during an emergency service call) | | | | | | | | | | | | | | | | | | | +| 0x0080 | 6way | | | | | | | | | | | | | | | | | | | +| 0x0100..0x8000 | Not used | | | | | | | | | | | | | | | | | | | +| Call presentation features: |

This attribute is a bit map of call presentation features. The value 0 disables the feature; 1 enables it.

0x0001Message waiting indication splash ring
0x0002Message waiting indication special dial tone
0x0004Message waiting indication visual indication
0x0008Call forwarding indication
0x0010..0x8000Not used

The default value is disabled. (R, W, Set-by-create) (mandatory) (2 bytes)

| 0x0001 | Message waiting indication splash ring | 0x0002 | Message waiting indication special dial tone | 0x0004 | Message waiting indication visual indication | 0x0008 | Call forwarding indication | 0x0010..0x8000 | Not used | | | | | | | | | +| 0x0001 | Message waiting indication splash ring | | | | | | | | | | | | | | | | | | | +| 0x0002 | Message waiting indication special dial tone | | | | | | | | | | | | | | | | | | | +| 0x0004 | Message waiting indication visual indication | | | | | | | | | | | | | | | | | | | +| 0x0008 | Call forwarding indication | | | | | | | | | | | | | | | | | | | +| 0x0010..0x8000 | Not used | | | | | | | | | | | | | | | | | | | + +**Direct connect feature:** This attribute is a bit map of characteristics associated with the direct connect feature. The value 0 disables the feature; 1 enables it. + +| | | +|------|--------------------------------| +| 0x01 | Direct connect feature enabled | +| 0x02 | Dial tone feature delay option | + +The default value is disabled. (R, W, Set-by-create) (mandatory) (1 byte) + +**Direct connect URI pointer:** If this attribute is set to its default value 0xFFFF, no URI is defined. Otherwise, this attribute points to a network address managed entity that specifies the URI of the direct connect. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Bridged line agent URI pointer:** If this attribute is set to its default value 0xFFFF, no URI is defined. Otherwise, this attribute points to a network address managed entity that specifies the URI of the bridged line agent. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Conference factory URI pointer:** If this attribute is set to its default value 0xFFFF, no URI is defined. Otherwise, this attribute points to a network address managed entity that specifies the URI of the conference factory. (R, W, Set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.9.9 VoIP feature access codes** + +The VoIP feature access codes managed entity defines administrable feature access codes for the VoIP subscriber. It is optional for ONTs that support VoIP service. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +Instances of the managed entity are created and deleted by the OLT. A VoIP feature access codes managed object is needed for each unique set of feature access code attributes. + +#### *Relationships* + +An instance of this managed entity may be associated with one or more SIP user data managed entities. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R) (mandatory) (2 bytes) + +The remaining attributes are access codes for the features mentioned in their names. Each attribute is a string of characters from the set {0..9, \*, #}, with trailing nulls in any unused bytes. + +**Cancel call waiting:** (R, W) (optional) (5 bytes) + +**Call hold:** (R, W) (optional) (5 bytes) + +**Call park:** (R, W) (optional) (5 bytes) + +**Caller ID activate:** (R, W) (optional) (5 bytes) + +**Caller ID deactivate:** (R, W) (optional) (5 bytes) + +| | | +|-------------------------------------|-----------------------------| +| Do not disturb activation: | (R, W) (optional) (5 bytes) | +| Do not disturb deactivation: | (R, W) (optional) (5 bytes) | +| Do not disturb PIN change: | (R, W) (optional) (5 bytes) | +| Emergency service number: | (R, W) (optional) (5 bytes) | +| Intercom service: | (R, W) (optional) (5 bytes) | + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.9.10 Network dial plan table** + +The network dial plan table ME is optional for ONTs providing VoIP service. This ME is used to provision dial plans from the OLT. Instances of this managed entity are created and deleted by the OLT. If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +#### *Relationships* + +An instance of this managed entity may be associated with one or more instances of the SIP user data managed entity. + +#### *Attributes* + +| | | +|----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) | +| Dial plan number: | This attribute indicates the current number of dial plans in the dial plan table. Default value is 0. (R) (mandatory) (2 bytes) | +| Dial plan table max size: | This attribute defines the maximum number of dial plans that can be stored in the dial plan table. (R, Set-by-create) (mandatory) (2 bytes) | +| Critical dial timeout: | This attribute defines the critical dial timeout for digit map processing in milliseconds. The default value is 4000 ms. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Partial dial timeout: | This attribute defines the partial dial timeout for digit map processing in milliseconds. The default value is 16000 ms. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Dial plan format: | This attribute defines the dial plan format standard that is supported in the ONT for VoIP. Valid values include:
0 Not defined.
1 H.248 format with specific plan (table entries define the dialling plan).
2 NSC format.
3 Vendor-specific format.
The default is 1. (R, W, Set-by-create) (mandatory) (1 byte) | +| Dial plan table: | The table contains a dial plan used by the VoIP service, along with fields to manage the table. These table attributes are further described below. (R, W) (mandatory) (30N bytes, where N is the number of dial plans) | + +| | | +|-------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Dial plan id: | A unique identifier of a dial plan within the dial plan table. (1 byte) | +| Action: | Remove (0) or add (1) this plan (set action). When a dial plan is being removed, only the dial plan id field is used to identify the dial plan token. (1 byte) | +| Dial plan token: | Token used by the VoIP service to process dial plans. This ASCII string is typically delimited by ":". (28 bytes) | + +#### *Actions* + +##### **Create, delete, get, get next, set** + +#### *Notifications* + +None. + +### **9.9.11 VoIP line status** + +The VoIP line status managed entity contains line status information for POTS ports using VoIP service. An ONT that supports VoIP automatically creates or deletes an instance of this managed entity upon creation or deletion of a PTP POTS UNI. + +#### *Relationships* + +An instance of this managed entity is associated with a PTP POTS UNI. + +#### *Attributes* + +| | | +|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point POTS UNI. (R) (mandatory) (2 bytes) | +| voip codec used: |

Reports the current codec used for a VoIP POTS port. Valid values are taken from [IETF RFC 3551], the same as specified in the codec selection attribute in the VoIP media profile:

  • 0 PCMU
  • 1 Reserved
  • 2 Reserved
  • 3 GSM
  • 4 G723
  • 5 DVI4
  • 6 DVI4
  • 7 LPC
  • 8 PCMA
  • 9 G722
  • 10 L16, 2 channels
  • 11 L16, 1 channel
  • 12 QCELP
  • 13 CN
  • 14 MPA
  • 15 G728
  • 16 DVI4
  • 17 DVI4
  • 18 G729

(R) (mandatory) (2 bytes)

| + +**voip voice server status:** Status of the VoIP session for this POTS port: + +- 0 None/initial +- 1 Registered +- 2 In session +- 3 Failed registration – icmp error +- 4 Failed registration – failed tcp +- 5 Failed registration – failed authentication +- 6 Failed registration – timeout +- 7 Failed registration – server fail code +- 8 Failed invite – icmp error +- 9 Failed invite – failed tcp +- 10 Failed invite – failed authentication +- 11 Failed invite – timeout +- 12 Failed invite – server fail code +- 13 Port not configured +- 14 Config done + +(R) (mandatory) (1 byte) + +**voip port session type:** This attribute reports the current state of a VoIP POTS port session: + +- 0 Idle/none +- 1 2way +- 2 3way +- 3 Fax +- 4 Telem +- 5 Conference + +(R) (mandatory) (1 byte) + +**voip call 1 packet period:** This attribute reports the packet period for the first call on the VoIP POTS port. The value is defined in milliseconds. (R) (mandatory) (2 bytes) + +**voip call 2 packet period:** This attribute reports the packet period for the second call on the VoIP POTS port. The value is defined in milliseconds. (R) (mandatory) (2 bytes) + +**voip call 1 dest addr:** This attribute reports the destination address for the first call on the VoIP POTS port. The value is an ASCII string. (R) (mandatory) (25 bytes) + +**voip call 2 dest addr:** This attribute reports the destination address for the second call on the VoIP POTS port. The value is an ASCII string. (R) (mandatory) (25 bytes) + +#### *Actions* + +#### **Get** + +#### *Notifications* + +None. + +### **9.9.12 Call control performance monitoring history data** + +This managed entity collects performance monitoring data related to the call control channel. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity is associated with an instance of the PPTP POTS UNI managed entity. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the PPTP POTS UNI. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Call setup failures:** This attribute counts call setup failures. (R) (mandatory) (4 bytes) +- Call setup timer:** This attribute is a high water mark that records the longest duration of a single call setup detected during this interval. Time is measured in milliseconds from the time an initial setup was requested by the subscriber until the time at which a response was provided to the subscriber in the form of busy tone, audible ring tone, etc. (R) (mandatory) (4 bytes) +- Call terminate failures:** This attribute counts the number of calls that were terminated with cause. (R) (mandatory) (4 bytes) +- Analog port releases:** This attribute counts the number of analogue port releases without dialling detected (abandoned calls). (R) (mandatory) (4 bytes) +- Analog port off-hook timer:** This attribute is a high water mark that records the longest period of a single off-hook detected on the analogue port. Time is measured in milliseconds. (R) (mandatory) (4 bytes) + +#### Actions + +##### Create, delete, get, set + +##### Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|------------------------------------|------------------------------------| +| 0 | CCPM call setup fail | 1 | +| 1 | CCPM setup timeout | 2 | +| 2 | CCPM call terminate | 3 | +| 3 | CCPM port release with no dialling | 4 | +| 4 | CCPM port offhook timeout | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.9.13 RTP performance monitoring history data + +NOTE – This managed entity was formerly known under the name RTP monitoring data. + +This managed entity collects performance monitoring data related to an RTP session. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the PPTP POTS UNI managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the PPTP POTS UNI ME. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- RTP errors:** This attribute counts RTP packet errors. (R) (mandatory) (4 bytes) +- Packet loss:** This attribute represents the fraction of packets lost. This attribute is calculated at the end of the 15-minute interval, and is undefined under the get current data action. The value 0 indicates no packet loss, scaling linearly to 0xFFFF to indicate 100% packet loss (zero divided by zero is defined to be zero). (R) (mandatory) (4 bytes) +- Maximum jitter:** This attribute is a high water mark that represents the maximum jitter identified during the measured interval, expressed in RTP timestamp units. (R) (mandatory) (4 bytes) +- Maximum time between RTCP packets:** This attribute is a high water mark that represents the maximum time between RTCP packets during the measured interval, in milliseconds. (R) (mandatory) (4 bytes) +- Buffer underflows:** This attribute counts the number of times the reassembly buffer underflows. In case of continuous underflow caused by a loss of IP packets, a single buffer underflow should be counted. If the interworking function is implemented with multiple buffers, such as a packet level buffer and a bit level buffer, then underflow of either buffer increments this counter. (R) (mandatory) (4 bytes) +- Buffer overflows:** This attribute counts the number of times the reassembly buffer overflows. If the interworking function is implemented with multiple buffers, such as a packet level buffer and a bit level buffer, then overflow of either buffer increments this counter. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note 2) | +|--------|---------------------------------|--------------------------------------| +| 0 | RTP PM RTP packet loss (Note 1) | 1 | +| 1 | RTP PM packet jitter | 2 | +| 2 | RTP PM no RTCP packet | 3 | +| 3 | RTP PM timeout | 4 | +| 4 | RTP PM buffer underflows | 6 | +| 5 | RTP PM buffer overflows | 7 | + +NOTE 1 – Since packet loss is undefined until the end of the interval, this TCA may only be issued at the interval boundary, whereupon it is then immediately cleared. + +NOTE 2 – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.9.14 SIP agent performance monitoring history data + +NOTE – This managed entity was formerly known by the name SIP agent monitoring data. + +This managed entity collects performance monitoring data for the associated VoIP SIP agent. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity is associated with a SIP agent config data or SIP config portal object. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the corresponding SIP agent config data. If a non-OMCI configuration method is used for VoIP, the managed entity id is 0. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Transactions:** This attribute counts the number of new transactions that were initiated. (R) (optional) (4 bytes) +- Rx invite reqs:** This attribute counts received invite messages, including retransmissions. (R) (optional) (4 bytes) +- Rx invite retrans:** This attribute counts received invite retransmission messages. (R) (optional) (4 bytes) +- Rx noninvite reqs:** This attribute counts received non-invite messages, including retransmissions. (R) (optional) (4 bytes) +- Rx noninvite retrans:** This attribute counts received non-invite retransmission messages. (R) (optional) (4 bytes) + +| | | +|-------------------------------------|------------------------------------------------------------------------------------------------------------| +| Rx response: | This attribute counts total responses received. (R) (optional) (4 bytes) | +| Rx response retransmissions: | This attribute counts total response retransmissions received. (R) (optional) (4 bytes) | +| Tx invite reqs: | This attribute counts transmitted invite messages, including retransmissions. (R) (optional) (4 bytes) | +| Tx invite retrans: | This attribute counts transmitted invite retransmission messages. (R) (optional) (4 bytes) | +| Tx noninvite reqs: | This attribute counts transmitted non-invite messages, including retransmissions. (R) (optional) (4 bytes) | +| Tx noninvite retrans: | This attribute counts transmitted non-invite retransmission messages. (R) (optional) (4 bytes) | +| Tx response: | This attribute counts the total responses sent. (R) (optional) (4 bytes) | +| Tx response retransmissions: | This attribute counts total response retransmissions sent. (R) (optional) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +**Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|----------------------------------------|------------------------------------| +| 0 | SIPAMD rx invite req | 1 | +| 1 | SIPAMD rx invite req retransmission | 2 | +| 2 | SIPAMD rx noninvite req | 3 | +| 3 | SIPAMD rx noninvite req retransmission | 4 | +| 4 | SIPAMD rx response | 5 | +| 5 | SIPAMD rx response retransmission | 6 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.9.15 SIP call initiation performance monitoring history data** + +This managed entity collects performance monitoring data related to call initiations of a VoIP SIP agent. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the SIP agent config data or SIP config portal ME. + +#### *Attributes* + +| | | +|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of SIP agent config data. If a non-OMCI configuration method is used for VoIP, the managed entity id is 0. (R, Set-by-create) (mandatory) (2 bytes) | +|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| + +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Failed to connect counter:** This attribute counts the number of times the SIP UA failed to reach/connect its TCP/UDP peer during SIP call initiations. (R) (mandatory) (4 bytes) +- Failed to validate counter:** This attribute counts the number of times the SIP UA failed to validate its peer during SIP call initiations. (R) (mandatory) (4 bytes) +- Timeout counter:** This attribute counts the number of times the SIP UA timed out during SIP call initiations. (R) (mandatory) (4 bytes) +- Failure received counter:** This attribute counts the number of times the SIP UA received a failure error code during SIP call initiations. (R) (mandatory) (4 bytes) +- Failed to authenticate counter:** This attribute counts the number of times the SIP UA failed to authenticate itself during SIP call initiations. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|------------------------------------|------------------------------------| +| 0 | SIP call PM failed connect | 1 | +| 1 | SIP call PM failed to validate | 2 | +| 2 | SIP call PM timeout | 3 | +| 3 | SIP call PM failure recv | 4 | +| 4 | SIP call PM failed to authenticate | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.9.16 MGC config data** + +The MGC config data ME defines the media gateway controller configuration associated with an MG subscriber. It is conditionally required for ONTs that support H.248 VoIP service. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the MGC config portal ME. + +Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be associated with one or more VoIP voice CTP managed entities. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) +- Primary MGC:** This attribute points to a network address ME that contains the name (IP address or resolved name) of the primary MGC that controls the signalling messages. The port is optional and defaults to 2944 for text message formats and 2955 for binary message formats. (R, W, Set-by-create) (mandatory) (2 bytes) +- Secondary MGC:** This attribute points to a network address ME that contains the name (IP address or resolved name) of the secondary or backup MGC that controls the signalling messages. The port is optional and defaults to 2944 for text message formats and 2955 for binary message formats. (R, W, Set-by-create) (mandatory) (2 bytes) +- TCP/UDP pointer:** This attribute points to the TCP/UDP config data ME to be used for communication with the MGC. The default value 0 is a null pointer. (R, W, Set-by-create) (mandatory) (2 bytes) +- Version:** This integer attribute reports the version of the Megaco protocol in use. (R, W, Set-by-create) (mandatory) (1 byte) +- Message format:** This attribute defines the message format. Valid values are: +0 Text long +1 Text short +2 Binary +The default value is 0. (R, W, Set-by-create) (mandatory) (1 byte) +- Maximum retry time:** This attribute specifies the maximum retry time for MGC transactions, in seconds. The default value 0 specifies vendor-specific implementation (R, W) (optional) (2 bytes) +- Maximum retry attempts:** This attribute specifies the maximum number of times a message is retransmitted to the MGC. The default value 0 specifies vendor-specific implementation. (R, W, Set-by-create) (optional) (2 bytes) +- Service change delay:** The attribute specifies the service status delay time for changes in line service status. This attribute is specified in seconds. The default value 0 specifies no delay. (R, W) (optional) (2 bytes) +- Termination ID base:** The attribute specifies the base string for the H.248 physical termination id(s) for this ONT. This string is intended to uniquely identify an ONT. Vendor-specific termination identifiers (i.e., port IDs) are optionally added to this string to uniquely identify a termination on a specific ONT. (R, W) (optional) (25 bytes) +- Softswitch:** This attribute identifies the gateway softswitch vendor. The format is four ASCII coded alphabetic characters [A..Z] as defined in [ATIS-0322000]. A value of four null characters indicates no particular vendor. (R, W, Set-by-create) (mandatory) (4 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +#### Notifications + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|--------------------------------| +| 0 | Timeout | Timeout of association with MG | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.9.17 MGC performance monitoring history data + +NOTE – This managed entity was formerly known under the name MGC monitoring data. + +The MGC monitoring data managed entity provides run-time statistics for an active MGC association. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### Relationships + +An instance of this managed entity is associated with an instance of the MGC config data or MGC config portal ME. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the associated MGC config data. If a non-OMCI configuration method is used, the managed entity id is 0. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) +- Received messages:** This attribute counts the number of received Megaco messages on this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) +- Received octets:** This attribute counts the total number of octets received on this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) +- Sent messages:** This attribute counts the total number of Megaco messages sent over this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) +- Sent octets:** This attribute counts the total number of octets sent over this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) +- Protocol errors:** This attribute counts the total number of errors detected on this association, as defined by [ITU-T H.341]. This includes: +- Syntax errors detected in a given received message. + - Outgoing transactions that failed for protocol reasons. +- (R) (mandatory) (4 bytes) +- Transport losses:** This attribute counts the total number of transport losses (for example, socket problems) detected on this association. A link loss is defined as loss of communication with the remote entity due to hardware/transient + +problems, or problems in related software. (R) (mandatory) (4 bytes) + +**Last detected event:** This attribute reports the last event detected on this association. This includes events such as the link failing or being set up. This field is an enumeration: + +- 0 No event – No event has been detected as yet. +- 1 Link up – The transport link underpinning the association came up. +- 2 Link down – The transport link underpinning the association went down. +- 3 Persistent error – A persistent error was detected on the link (such as the socket/TCP connection to the remote node could not be set up). +- 4 Local shutdown – The association was brought down intentionally by the local application. +- 5 Failover down – The association was brought down as part of failover processing. +- 255 Other event – The last event does not match any in the list. + +(R) (mandatory) (1 byte) + +**Last detected event time:** This attribute reports the time in seconds since the last event on this association was detected, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) + +**Last detected reset time:** This attribute reports the time in seconds since these statistics were last reset, as defined by [ITU-T H.341]. Under normal circumstances, a get action on this attribute would return 900 seconds to indicate a completed 15-minute interval. (R) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | MGCP protocol errors | 1 | +| 1 | MGCP transport losses | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.9.18 VoIP config data** + +The VoIP configuration data managed entity defines the configuration for VoIP in the ONT. The OLT uses this ME to discover the VoIP signalling protocols and configuration methods supported by this ONT. The OLT then uses this ME to select the desired signalling protocol and configuration method. The entity is conditionally required for ONTs that offer VoIP services. + +An ONT that supports VoIP services automatically creates an instance of this managed entity. + +#### *Relationships* + +One instance of the managed entity is associated with the ONT. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Available signalling protocols:** This attribute is a bit map that defines the VoIP signalling protocols supported in the ONT. Valid values are any combination of: + +| | | +|---|---------------------------| +| 0 | None, VoIP not supported. | +| 1 | SIP. | +| 2 | H.248. | +| 4 | MGCP. | + +(R) (mandatory) (1 byte) + +**Signalling protocol used:** This attribute specifies the VoIP signalling protocol to use. Only one type of protocol is allowed at a time. Valid values are: + +| | | +|------|--------------------------------------------| +| 0 | None. | +| 1 | SIP. | +| 2 | H.248. | +| 3 | MGCP. | +| 0xFF | Selected by non-OMCI management interface. | + +(R, W) (mandatory) (1 byte) + +**Available VoIP configuration methods:** This attribute is a bit map that indicates the capabilities of the ONT with regard to VoIP service configuration: + +| | | +|---|-------------------------------------------------------------------------------------------| +| 1 | ONT capable of using OMCI to configure its VoIP services. | +| 2 | ONT capable of working with configuration file retrieval to configure its VoIP services. | +| 4 | ONT capable of working with DSL Forum TR-69 to configure its VoIP services. | +| 8 | ONT capable of working with IETF sipping config framework to configure its VoIP services. | + +Bits 5..24 are reserved for future use. Bits 25..32 are reserved for proprietary vendor configuration capabilities. (R) (mandatory) (4 bytes) + +**VoIP configuration method used:** Specifies which method is used to configure the ONT's VoIP service. + +| | | +|----------|--------------------------------------------------------| +| 0 | Do not configure – ONT default. | +| 1 | OMCI. | +| 2 | Configuration file retrieval. | +| 3 | DSL Forum TR-69. | +| 4 | IETF sipping config framework. | +| 5..240 | Reserved for future use. | +| 241..255 | Reserved for proprietary vendor configuration methods. | + +(R, W) (mandatory) (1 byte) + +**VoIP configuration address pointer:** If this attribute is set to any value other than 0xFFFF, it points to a network address managed entity, which indicates the address of the server to contact using the method indicated in the VoIP configuration method used attribute. This attribute is only relevant for non-OMCI configuration methods. + +If this attribute is set to 0xFFFF, no address is defined by this attribute. However, the address may be defined by other methods, such as deriving it from the ONT identifier attribute of the IP host config data ME and + +using a well-known URI schema. (The default value is 0xFFFF.) (R, W) (mandatory) (2 bytes) + +##### **VoIP configuration state:** + +Indicates the status of the ONT VoIP service. + +- 0 Inactive: Configuration retrieval has not been attempted. +- 1 Active: Configuration was retrieved. +- 2 Initializing: Configuration is now being retrieved. +- 3 Fault: Configuration retrieval process failed. + +Other values are reserved. At ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (1 byte) + +##### **Retrieve profile:** + +This attribute provides a means by which the ONT may be notified that a new VoIP profile should be retrieved. By setting this attribute, the OLT triggers the ONT to retrieve a new profile. The actual value in the set action is ignored because it is the action of setting that is important. (W) (mandatory) (1 byte) + +##### **Profile version:** + +This attribute is a character string that identifies the version of the last retrieved profile. (R) (mandatory) (25 bytes) + +#### *Actions* + +##### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-----------------------------------| +| 1..7 | N/A | | +| 8 | Profile version | Version of last retrieved profile | +| 9..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|--------|----------------------------|---------------------------------------------------------------------------------------------------------| +| 0 | VCD config server name | Failed to resolve the configuration server name | +| 1 | VCD config server reach | Cannot reach configuration server (the port cannot be reached, ICMP errors) | +| 2 | VCD config server connect | Cannot connect to configuration server (due to bad credentials or other fault after the port responded) | +| 3 | VCD config server validate | Cannot validate configuration server | +| 4 | VCD config server auth | Cannot authenticate configuration session (e.g., missing credentials) | +| 5 | VCD config server timeout | Timeout waiting for response from configuration server | +| 6 | VCD config server fail | Failure response received from configuration server | +| 7 | VCD config file error | Configuration file received has an error | +| 8 | VCD subscription name | Failed to resolve the subscription server name | +| 9 | VCD subscription reach | Cannot reach subscription server (the port cannot be reached, ICMP errors) | +| 10 | VCD subscription connect | Cannot connect to subscription server (due to bad credentials or other fault after the port responded) | + +##### Alarm + +| Number | Alarm | Description | +|----------|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 11 | VCD subscription validate | Cannot validate subscription server | +| 12 | VCD subscription auth | Cannot authenticate subscription session (e.g., missing credentials) | +| 13 | VCD subscription timeout | Timeout waiting for response from subscription server | +| 14 | VCD subscription fail | Failure response received from subscription server | +| 15 | VCD reboot request | A non-OMCI management interface has requested a reboot of the ONT.
NOTE – This alarm is used only to indicate the request and not to indicate that a reboot has actually taken place. | +| 16..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.9.19 SIP config portal + +The SIP config portal managed entity provides a way for the OLT to discover the configuration text delivered to an ONT by a non-OMCI SIP VoIP configuration method (TR-69, Sipping framework, etc.). Text retrieved from this ME is not required to be understood by the OLT or EMS, but it may be useful for human or vendor-specific analysis tools. See also the MGC config portal ME. + +An instance of this managed entity may be created by an ONT that supports non-OMCI SIP configuration. It is not reported during a MIB upload. + +#### Relationships + +One instance of this managed entity is associated with the ONT. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this managed entity. There is one instance, number 0. (R) (mandatory) (2 bytes) + +**Configuration text table:** This attribute is used to pass a textual representation of the VoIP configuration back to the OLT. The contents are vendor-specific. The get, get next sequence must be used with this attribute since its size is unspecified. Upon ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (x bytes) + +#### Actions + +##### Get, get next + +#### Notifications + +##### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Configuration text | Indicates an update to the VoIP configuration from a non-OMCI interface. Because the attribute is a table, the AVC contains no information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 2..16 | Reserved | | + +### 9.9.20 MGC config portal + +The MGC (media gateway controller) config portal managed entity provides a way for the OLT to discover the configuration text delivered to an ONT by a non-OMCI H.248 VoIP configuration method. Text retrieved from this ME is not required to be understood by the OLT or EMS, but it may be useful for human or vendor-specific analysis tools. See also the SIP config portal ME. + +An instance of this managed entity may be created by an ONT that supports non-OMCI H.248 configuration. It is not reported during a MIB upload. + +#### *Relationships* + +One instance of this managed entity is associated with the ONT. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is one instance, number 0. (R, Set-by-create) (mandatory) (2 bytes) + +**Configuration text table:** This attribute is used to pass a textual representation of the VoIP configuration back to the OLT. The contents are vendor-specific. The get, get next sequence must be used with this attribute since its size is unspecified. Upon ME instantiation, the ONT sets this attribute to 0. (R) (mandatory) (x bytes) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Configuration text | Indicates an update to the VoIP configuration from a non-OMCI interface. Because the attribute is a table, the AVC contains no information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 2..16 | Reserved | | + +### 9.9.21 Physical path termination point ISDN UNI + +This managed entity represents the point at a basic rate ISDN UNI where physical paths terminate and physical path level functions (e.g., analogue telephony, facsimile function) are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has ISDN ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of ISDN type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of ISDN type. Note that the installation of a plug-and-play card may indicate the presence of ISDN ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies ISDN ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect an ISDN circuit pack, nor is it equipped with an ISDN circuit pack. + +#### *Relationships* + +One or more instances of this managed entity are associated with the ONT-G or a circuit pack managed entity classified as ISDN type. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) +- Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) +- Interworking pointer:** This attribute points to the instance of the GEM interworking termination point managed entity to which this instance is connected. The value 0 is a null pointer. (R, W) (optional) (2 bytes) +- D channel ID:** This attribute contains the channel identifier of the connection transporting the D channel associated with this ISDN BRI port. (R, W) (mandatory) (1 byte) +- B1 channel ID:** This attribute contains the channel identifier of the connection transporting the B1 channel associated with this ISDN BRI port. (R, W) (mandatory) (1 byte) +- B2 channel ID:** This attribute contains the channel identifier of the connection transporting the B2 channel associated with this ISDN BRI port. (R, W) (mandatory) (1 byte) +- ARC:** See clause I.1.8. (R, W) (optional) (1 byte) +- ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) +- ISDN loopback configuration:** This attribute controls the loopback configuration of this physical interface. +- 0 No loopback. + - 1 Simultaneous loopback of all channels. + - 1 Loopback of D channel only [sic]. + - 2 Loopback of B1 channel only. + - 3 Loopback of B2 channel only. +- Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +- Test:** Request that the ONT perform one or more MLT tests. See test and test result message layouts in clauses II.2.27 and II.2.45. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------| +| 1..5 | N/A | | +| 6 | ARC | ARC timer expiration | +| 7..8 | N/A | | +| 9..16 | Reserved | | + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|--------------------------| +| 0 | AIS | Alarm indication signal | +| 1 | RDI | Remote defect indication | +| 2..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +## 9.10 MoCA + +This clause defines managed entities associated with MoCA UNIs, as shown in Figure 9.10-1. + +![Diagram showing managed entities associated with MoCA UNIs. A central box labeled '9.10.1: PTP MoCA UNI' is connected to two other boxes: '9.10.2: MoCA Ethernet PM history data' and '9.10.3: MoCA interface PM history data'. Arrows point from the central box to these two boxes. On the left, two labels with arrows pointing to the central box are: 'Implicit links: Extended VLAN tagging operation config data' and 'Pointed to by: 802.1p mapper service profile, VLAN tagging operation config data, IP port config data'.](491c4b332cae19f28c7e922759c0f88b_img.jpg) + +Diagram showing managed entities associated with MoCA UNIs. A central box labeled '9.10.1: PTP MoCA UNI' is connected to two other boxes: '9.10.2: MoCA Ethernet PM history data' and '9.10.3: MoCA interface PM history data'. Arrows point from the central box to these two boxes. On the left, two labels with arrows pointing to the central box are: 'Implicit links: Extended VLAN tagging operation config data' and 'Pointed to by: 802.1p mapper service profile, VLAN tagging operation config data, IP port config data'. + +Figure 9.10-1 – Managed entities associated with MoCA UNIs + +### 9.10.1 Physical path termination point MoCA UNI + +This managed entity represents a MoCA UNI, where physical paths terminate and physical path level functions (i.e., the MoCA function) are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has MoCA ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of MoCA type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of MoCA type. Note that the installation of a plug-and-play card may indicate the presence of MoCA ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies MoCA ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect a MoCA circuit pack, nor is it equipped with a MoCA circuit pack. + +#### Relationships + +An instance of this managed entity is associated with each real or preprovisioned MoCA port. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number is directly associated with the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Loopback configuration:** This attribute sets the MoCA loopback configuration: + +- 0 No loopback. +- 3 Loopback3, loopback of downstream traffic after PHY transceiver, depicted in Figure 9.10.1-1. + +Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (optional) (1 byte) + +![Diagram of MoCA loopback configuration. An ONT (Optical Network Terminal) box contains a 'PHY transceiver'. A 'MoCA UNI' (User Network Interface) is connected to the left side of the PHY transceiver. A 'PON' (Passive Optical Network) is connected to the right side of the ONT. A curved arrow labeled 'Loopback 3' originates from the output of the PHY transceiver and loops back to its input, indicating the path of the loopback signal.](e0eba715b26e99c0beececdd6112ee58_img.jpg) + +Diagram of MoCA loopback configuration. An ONT (Optical Network Terminal) box contains a 'PHY transceiver'. A 'MoCA UNI' (User Network Interface) is connected to the left side of the PHY transceiver. A 'PON' (Passive Optical Network) is connected to the right side of the ONT. A curved arrow labeled 'Loopback 3' originates from the output of the PHY transceiver and loops back to its input, indicating the path of the loopback signal. + +**Figure 9.10.1-1 – MoCA loopback configuration** + +Note that normal bridge behaviour may defeat the loopback signal, unless broadcast MAC addresses are used. + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Max frame size:** This attribute denotes the maximum frame size allowed across this interface. Upon ME instantiation, the ONT sets this attribute to 1518. (R, W) (mandatory) (2 bytes) + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +**PPPoE filter:** This attribute controls filtering of PPPoE packets on this MoCA port. When its value is 1, all packets other than PPPoE packets are discarded. The default 0 accepts packets of all types. (R, W) (optional) (1 byte) + +**Network status:** This attribute indicates the networking state of the MoCA interface. + +- 0 The interface has not joined a MoCA network. +- 1 The interface has joined a MoCA network. +- 2 The interface has joined a MoCA network and is currently the network coordinator. + +(R) (mandatory) (1 byte) + +- Password:** This attribute specifies the MoCA encryption key. It is an ASCII string of 17 decimal digits. Upon ME instantiation, the ONT sets this attribute to 17 null bytes. (R, W) (mandatory) (17 bytes) +- Privacy enabled:** This attribute activates (1) link-layer security. The default value 0 deactivates it. (R, W) (mandatory) (1 byte) +- Minimum bandwidth alarm threshold:** This attribute specifies the minimum desired PHY link bandwidth between two nodes. If the actual bandwidth is lower, a limited link alarm is declared. Valid values are 0 to 0x0410 (260 Mbit/s) in 0.25-Mbit/s increments. The default value is 0x02D0 (180 Mbit/s). The value 0 disables the threshold. (R, W) (optional) (2 bytes) +- Frequency mask:** This attribute is a bit map of the centre frequencies that the interface is permitted to use, where each bit represents a centre frequency. The least significant bit (b[1]) corresponds to centre frequency 800 MHz. The next significant bit (b[2]) corresponds to centre frequency 825 MHz. The 28th bit (b[28]) corresponds to a centre frequency 1500 MHz. The 4 most significant bits are not used. (R, W) (optional) (4 bytes) +- RF channel:** This attribute reports the frequency to which the MoCA interface is currently tuned, in MHz. (R) (mandatory) (2 bytes) +- Last operational frequency:** This attribute reports the frequency to which the MoCA interface was tuned when last operational, in MHz. (R) (mandatory) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------| +| 1..2 | N/A | | +| 3 | Op state | Operational state | +| 4 | N/A | | +| 5 | ARC | ARC timer expiration | +| 6..14 | N/A | | +| 15..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|----------|-------------------------|--------------------------------------------------------------------------------------| +| 0 | MoCA loss of link (LOL) | Loss of link at the MoCA Interface | +| 1 | MoCA limited link (LL) | Bandwidth of link between two nodes on the MoCA network is less than specified value | +| 2..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.10.2 MoCA Ethernet performance monitoring history data** + +This managed entity collects performance monitoring data for a MoCA Ethernet interface. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the PPTP MoCA UNI managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point MoCA UNI. (R, Set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 and 2 managed entities that contains PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) + +Incoming PM refers to upstream traffic received on the UNI; outgoing PM refers to downstream traffic transmitted on the UNI. + +- Incoming unicast packets:** (R) (optional) (4 bytes) +- Incoming discarded packets:** (R) (optional) (4 bytes) +- Incoming errored packets:** (R) (optional) (4 bytes) +- Incoming unknown packets:** (R) (optional) (4 bytes) +- Incoming multicast packets:** (R) (optional) (4 bytes) +- Incoming broadcast packets:** (R) (optional) (4 bytes) +- Incoming octets:** (R) (optional) (4 bytes) +- Outgoing unicast packets:** (R) (optional) (4 bytes) +- Outgoing discarded packets:** (R) (optional) (4 bytes) +- Outgoing errored packets:** (R) (optional) (4 bytes) +- Outgoing unknown packets:** (R) (optional) (4 bytes) +- Outgoing multicast packets:** (R) (optional) (4 bytes) +- Outgoing broadcast packets:** (R) (optional) (4 bytes) +- Outgoing octets:** (R) (optional) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|----------------------------|------------------------------------| +| 0 | Incoming unicast packets | 1 | +| 1 | Incoming discarded packets | 2 | +| 2 | Incoming error packets | 3 | +| 3 | Incoming unknown packets | 4 | +| 4 | Incoming multicast packets | 5 | +| 5 | Incoming broadcast packets | 6 | +| 6 | Incoming octets | 7 | +| 7 | Outgoing unicast packets | 8 | +| 8 | Outgoing discarded packets | 9 | +| 9 | Outgoing error packets | 10 | +| 10 | Outgoing unknown packets | 11 | +| 11 | Outgoing multicast packets | 12 | +| 12 | Outgoing broadcast packets | 13 | +| 13 | Outgoing octets | 14 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.10.3 MoCA interface performance monitoring history data + +This managed entity collects performance monitoring data for a MoCA interface. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +NOTE 1 – Be aware that the structure of this ME is an exception to the normal definition of PM MEs. It should not be used as a guide for the definition of future MEs. This managed entity has only current values, which are retrievable by get and get next operations; no history is retained. + +#### Relationships + +An instance of this managed entity is associated with an instance of the PPTP MoCA UNI managed entity. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the physical path termination point MoCA UNI. (R, Set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) + +**PHY tx broadcast rate:** This attribute indicates the MoCA PHY broadcast transmit rate from the ONT MoCA interface to all the nodes in bit/s. (R) (optional) (4 bytes) + +##### **Node table:** + +This attribute lists current nodes in the node table. The table contains MAC addresses and statistics for those nodes. These table attributes are further described below. + +**MAC address:** A unique identifier of a node within the table. (6 bytes) + +**PHY tx rate:** MoCA PHY unicast transmit rate from the ONT MoCA interface to the node identified by the MAC address, in bit/s. (4 bytes) + +**Tx power control reduction:** The reduction in transmitter level due to power control, in dB. Valid values range from 0 (full power) to 60. (1 byte) + +**PHY rx rate:** MoCA PHY unicast receive rate to the ONT MoCA interface from the node identified by the MAC address, in bit/s. (optional) (4 bytes) + +**Rx power level:** The power level received at the ONT MoCA interface from the node identified by the MAC address, in dBm, represented as a 2s complement integer. Valid values range from +10 (0x0A) to -80 (0xB0). (1 byte) + +**PHY rx broadcast rate:** MoCA PHY broadcast receive rate to the ONT MoCA interface from the node identified by MAC address, in bits/s. (optional) (4 bytes) + +**Rx broadcast power level:** The power level received at the ONT MoCA interface from the node identified by the MAC address, in dBm, represented as a 2s complement integer. Valid values range from +10 (0x0A) to -80 (0xB0). (1 byte) + +**Tx packet:** Number of packets transmitted to node. (4 bytes) + +**Rx packet:** Number of packets received from node. (4 bytes) + +**Rx errored and missed:** Number of errored and missed packets received from node. The sum of this field across all entries in the node table contributes to the rx errored and missed TCA. This field is reset to 0 on 15-minute boundaries. (4 bytes) + +**Rx errored:** Number of errored packets received from node. The sum of this field across all entries in the node table contributes to the rx errored TCA. This field is reset to 0 on 15-minute boundaries. (optional) (4 bytes) + +(R) (mandatory) (37N bytes, where N is the number of nodes in the node table) + +NOTE 2 – A table row is always 37 bytes. If optional fields are not supported, they should be set to 0. + +#### *Actions* + +**Create, delete, get, get next, set** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|-----------------------------|------------------------------------| +| 0 | Total rx errored and missed | 1 | +| 1 | Total rx errored | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## 9.11 Traffic management + +### 9.11.1 Priority queue-G + +This managed entity specifies the priority queue used by a GEM port network CTP. In the upstream direction, a priority queue-G ME is also related to a T-CONT ME. + +If $N$ priority queues reside in the ONT and its circuit packs, the ONT creates $N$ instances of the priority queue-G management entity following the creation of the circuit pack or T-CONT MEs. After the ONT creates T-CONT MEs, it autonomously creates instances of the priority queue-G ME. + +The OLT can find all the queues by reading the priority queue-G managed entity instances. If the OLT tries to retrieve a non-existent priority queue, the ONT denies the get action with an error indication. + +See also Appendix III. + +Upstream priority queues can be added to the ONT. Moreover, priority queues can exist in the ONT core and circuit packs serving both UNI and ANI functions. + +The weight attribute permits configuring an optional traffic scheduler. Several attributes support back pressure operation, whereby a back pressure signal is sent backward and causes the attached terminal to temporarily suspend sending data. + +#### Relationships + +One or more instances of this managed entity are associated with the ONT-G managed entity to model the upstream priority queues if the traffic management option attribute in the ONT-G ME is 0. + +One or more instances of this managed entity are associated with a circuit pack managed entity serving UNI functions as downstream priority queues. + +For an ONT that has one or more fixed user interfaces, one or more instances are associated with the ONT-G managed entity for the downstream priority queues. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The most significant bit represents the direction (1: upstream, 0: downstream). The 15 least significant bits represent a queue id. The queue id is numbered in ascending order by the ONT itself. It is strongly encouraged that the queue id be formulated to simplify finding related queues. One way to do this is to number the queues such that the related port attributes are in ascending order (for the downstream and upstream queues separately). The range of downstream queue ids is 0 to 0x7FFF and the range of upstream queue ids is 0x8000 to 0xFFFF. (R) (mandatory) (2 bytes) + +| | | +|---------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Queue configuration option: | This attribute identifies the buffer partitioning policy. The value 1 means that several queues share one buffer size of maximum queue size, while the value 0 means that each queue has an individual buffer of maximum queue size. (R) (mandatory) (1 byte) | +| Maximum queue size: | This attribute specifies the maximum size of the queue. Units are GEM block lengths. (R) (mandatory) (2 bytes) | +| Allocated queue size: | This attribute identifies the allocated size of this queue. Units are GEM block lengths. (R, W) (mandatory) (2 bytes) | +| Discard-block counter reset interval: | This attribute represents the interval in milliseconds at which the counter resets itself. (R, W) (optional) (2 bytes) | +| Threshold value for discarded blocks due to buffer overflow: | The threshold for the number of GEM block lengths discarded on this queue due to buffer overflow. (R, W) (optional) (2 bytes) | +| Related port: |

This attribute represents the slot, port/T-CONT and priority information associated with the instance of priority queue-G ME. This attribute comprises four bytes.

In the upstream direction, the first two bytes are the ME ID of the associated T-CONT. In the downstream direction, the first byte is the slot number and the second byte is the port number of the queue's destination port.

The last two bytes represent the priority of this queue. The range of priority is 0 to 0x0FFF. The value 0 indicates the highest priority and 0x0FFF indicates the lowest priority. (R) (mandatory) (4 bytes)

| +| Traffic scheduler-G pointer: | This attribute points to the traffic scheduler-G ME instance that is associated with this priority queue. This pointer is used when this priority queue is connected with a traffic scheduler. The default value is null (0). (R, W) (mandatory) (2 bytes) | +| Weight: | This attribute represents weight for WRR. This weight is used by the traffic scheduler or T-CONT (whose policy is WRR) indicated by the traffic scheduler-G pointer attribute or related port attribute. Upon ME instantiation, the ONT sets this attribute to 1. (R, W) (mandatory) (1 byte) | +| Back pressure operation: | This attribute enables (0) or disables (1) back pressure operation. Its default value is 0. (R, W) (mandatory) (2 bytes) | +| Back pressure time: | This attribute indicates the time for which the customer terminal temporarily suspends sending data. This attribute presents the duration in microseconds. This attribute can be used as a pause time for an Ethernet UNI. Values: 0 to 0xFFFF FFFF. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (4 bytes) | +| Back pressure occur queue threshold: | This attribute identifies the threshold size of this queue to start sending a back pressure signal. (R, W) (mandatory) (2 bytes) | +| Back pressure clear queue threshold: | This attribute identifies the threshold size of this queue to stop sending a back pressure signal. (R, W) (mandatory) (2 bytes) | + +#### *Actions* + +#### **Get, set** + +#### Notifications + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|-----------------------------------------------------------------------------------------------------------------------| +| 0 | Block loss | Content loss in excess of threshold. The alarm is cleared when the discard block counter reset interval next expires. | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.11.2 Traffic scheduler-G + +An instance of this managed entity represents a logical object that can control upstream GEM packets. A traffic scheduler can accommodate GEM packets after a priority queue or other traffic scheduler and transfer them toward the next traffic scheduler or T-CONT. Because T-CONTs and traffic schedulers are created autonomously by the ONT, the ONT vendor predetermines the most complex traffic handling model it is prepared to support; the OLT may use less than the ONT's full capabilities, but cannot ask for more. See Appendix III for more detail. + +After the ONT creates instances of T-CONT ME, it then autonomously creates instances of the traffic scheduler-G ME. + +#### Relationships + +The traffic scheduler-G ME may be related to a T-CONT or other traffic schedulers through pointer attributes. + +#### Attributes + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical capability that realizes the traffic scheduler. The first byte is the slot id of the circuit pack with which this traffic scheduler is associated. For a traffic scheduler that is not associated with a circuit pack, the first byte is 0xFF. The second byte is the traffic scheduler id, assigned by the ONT itself. Traffic scheduler ids are numbered in ascending order with range 0..0xFF in each circuit pack or ONT core. (R) (mandatory) (2 bytes) +- T-CONT pointer:** This attribute points to the T-CONT ME instance associated with this traffic scheduler. This pointer is used when this traffic scheduler is connected to the T-CONT directly. It is null (0) otherwise. (R) (mandatory) (2 bytes) +- Traffic scheduler pointer:** This attribute points to another traffic scheduler-G ME instance that may serve this traffic scheduler. This pointer is used when this traffic scheduler is connected to another traffic scheduler; it is null (0) otherwise. (R) (mandatory) (2 bytes) +- Policy:** This attribute represents scheduling policy. Valid values include +- 0 Null + - 1 HOL (head of line) + - 2 WRR (weighted round robin) +- (R) (mandatory) (1 byte) + +**Priority/weight:** This attribute represents priority for HOL scheduling or the weight for WRR scheduling. This value is used by the T-CONT or traffic scheduler indicated by the T-CONT pointer attribute or traffic scheduler pointer attribute. If the indicated pointer has policy = HOL, this value is interpreted as a priority (0 is the highest priority, 255 the lowest). If the indicated pointer has policy = WRR, this value is interpreted as a weight. Upon ME instantiation, the ONT sets this attribute to 0. (R, W) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### 9.11.3 GEM traffic descriptor + +This traffic descriptor set is applied to traffic regulation for upstream flows identified by GEM port-ID or MAC bridge port. If these flows are not regulated, this set is not used. + +#### *Relationships* + +This ME is associated with a GEM port network CTP. Upstream traffic flow identified by GEM port-ID or MAC bridge port is characterized by this ME. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**CIR** This attribute specifies the committed information rate, specified in byte/s. (R, W, Set-by-create) (optional) (4 bytes) + +**PIR:** This attribute specifies peak information rate, specified in byte/s. (R, W, Set-by-create) (optional) (4 bytes) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +## 9.12 General purpose MEs + +### 9.12.1 UNI-G + +This managed entity organizes data associated with user network interfaces (UNIs) supported by GEM. One instance of the UNI-G managed entity exists for each UNI supported by the ONT. + +The ONT automatically creates or deletes instances of this managed entity upon the creation or deletion of a real or virtual circuit pack managed entity, one per port. + +#### *Relationships* + +An instance of the UNI-G managed entity exists for each instance of a physical path termination point managed entity. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of a physical path termination point. (R) (mandatory) (2 bytes) + +**Configuration option status:** This attribute holds the UNI configuration code field. Its bits are assigned as shown below. + +| Bit | Name | Setting | +|-------|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------| +| 1 | N/A | | +| 2 | Server trail fault propagation TC layer | 0: All TC layer alarm reporting through the OMCC is inhibited.
1: TC layer alarm reporting through the OMCC is not inhibited. | +| 3 | Server trail fault propagation PHY layer | 0: All PHY layer alarm reporting through the OMCC is inhibited.
1: PHY layer alarm reporting through the OMCC is not inhibited. | +| 4 | Server trail fault propagation GAL layer | 0: All GAL layer alarm reporting through the OMCC is inhibited.
1: GAL layer alarm reporting through the OMCC is not inhibited. | +| 5..16 | Reserved | | + +(R, W) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this managed entity are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +#### Actions + +#### Get, set + +#### Notifications + +None. + +### 9.12.2 OLT-G + +NOTE – Except for its name, this managed entity is identical to the OLTB-PON ME documented in [ITU-T G.983.2]. + +This optional managed entity identifies the OLT to which an ONT is connected. This ME provides a way for the ONT to configure itself for operability with a particular OLT. + +An ONT that supports this managed entity automatically creates an instance of it. Immediately following the startup phase, the OLT should set the ONT to the desired configuration. Interpretation of the attributes is a matter for negotiation between the two vendors involved. + +#### Relationships + +One instance of this managed entity is associated with the ONT managed entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) +- OLT vendor id:** This attribute identifies the OLT vendor. It is the same as the 4 most significant bytes of an ONT serial number specified in [ITU-T G.984.3]. Upon instantiation, this attribute comprises all spaces. (R, W) (mandatory) (4 bytes) +- Equipment id:** This attribute may be used to identify the specific type of OLT. The default value of all spaces indicates that equipment ID information is not available or applicable to the OLT being represented. (R, W) (mandatory) (20 bytes) +- Version:** This attribute identifies the version of the OLT as defined by the vendor. The default left-justified ASCII string "0" (padded with trailing nulls) indicates that version information is not available or applicable to the OLT being represented. (R, W) (mandatory) (14 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +None. + +### **9.12.3 Network address** + +The network address managed entity associates a network address with security methods required to access a server. It is conditionally required for ONTs that support VoIP service. The address may take the form of a URI, a fully qualified path or IP address represented as an ASCII string. + +If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME or the MGC config portal ME. + +Instances of this managed entity are created and deleted by the OLT or the ONT depending on the method used and case. + +#### *Relationships* + +Any managed entity that requires a network address may link to an instance of this ME. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Instances of this managed entity created autonomously by the ONT have IDs in the range 0..0x7FFF. Instances created by the OLT have IDs in the range 0x8000..0xFFFE. The value 0xFFFF is not valid. (R, Set-by-create) (mandatory) (2 bytes) +- Security pointer:** If this attribute is set to its default value 0xFFFF, security attributes are not defined for this network address. If this attribute is set to any other value, it points to an authentication security method managed entity. The authentication security method indicates the username and password to be used when retrieving the network address indicated by this ME. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Address pointer:** This attribute points to the large string ME that contains the network address. It may contain a fully qualified domain name, URI or IP address. The URI may also contain an optional port identifier (e.g., "x.y.z.com:5060"). The default value 0xFFFF indicates that no network address is defined. (R, W, Set-by-create) (mandatory) (2 bytes). + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.12.4 Authentication security method** + +The authentication security method defines the user id/password configuration to establish a session between a client and server. This object may be used in the role of the client or server. An instance of this managed entity is created by the OLT if authenticated communication is necessary. + +#### *Relationships* + +One instance of this management entity may be associated with a network address ME. This ME may also be cited by other MEs that require authentication parameter management. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0xFFFF is not valid. (R, Set-by-create) (mandatory) (2 bytes) + +**Validation scheme:** This attribute specifies the validation scheme used when the ONT validates a challenge. Validation schemes are defined as follows: + +- 0 Validation disabled. +- 1 Validate using MD5 digest authentication as defined in [IETF RFC 2069] (recommended). +- 3 Validate using basic authentication as defined in [IETF RFC 2617]. + +(R, W) (mandatory) (1 byte) + +**Username 1:** This string attribute is the user name. If the string is shorter than 25 bytes, it must be null terminated (Note). (R, W) (mandatory) (25 bytes) + +**Password:** This string attribute is the password. If the string is shorter than 25 bytes, it must be null terminated. (R, W) (mandatory) (25 bytes) + +**Realm:** This string attribute specifies the realm used in digest authentication. If the string is shorter than 25 bytes, it must be null terminated. (R, W) (mandatory) (25 bytes) + +**Username 2:** This string attribute allows for continuation of the user name beyond 25 characters (Note). Its default value is a null string. (R, W) (optional) (25 bytes) + +NOTE – The total username is the concatenation of the username 1 and username 2 attributes if and only if a) username 1 comprises 25 non-null characters, b) username 2 is supported by the ONT, and c) username 2 contains a leading non-null character string. Otherwise, the total username is simply the value of the username 1 attribute. + +#### *Actions* + +#### **Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.12.5 Large string** + +The large string managed entity holds strings longer than 25 bytes, up to 375 bytes. It is maintained in up to 15 parts, each part containing 25 bytes. If the final part contains fewer than 25 bytes, it is terminated by at least one null byte. For example: + +| | | +|-----------------|---------------------------| +| Number of parts | 3 | +| Part 1 | sftp://myusername:mypassw | +| Part 2 | ord@config.telecom.com:12 | +| Part 3 | 34/path/to/filename | + +Or + +| | | +|-----------------|-------------------------------| +| Number of parts | 3 | +| Part 1 | sftp://myusername:mypassw | +| Part 2 | ord@config.telecom.com:12 | +| Part 3 | 34/path/to/longfilename | + +Instances of this managed entity are created and deleted by the OLT. To use this managed entity, the OLT instantiates the large string ME and then points to the created ME from other ME instances. Systems that maintain the large string should ensure that the large string ME is not deleted while it is still linked. + +#### *Relationships* + +An instance of this ME may be cited by any ME that requires a text string longer than 25 bytes. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The value 0xFFFF is not valid. (R, Set-by-create) (mandatory) (2 bytes) + +**Number of parts:** This attribute specifies the number of non-empty parts that form the large string. This attribute defaults to 0 to indicate no large string is defined. (R, W) (mandatory) (1 byte). + +Fifteen additional attributes are defined below; they are identical. The large string is simply divided into as many parts as necessary, starting at part 1. If the end of the string does not lie at a part boundary, it is marked with a null byte. + +**Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11, Part 12, Part 13, Part 14, Part 15:** (R, W) (mandatory) (25 bytes \* 15 attributes) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +### 9.12.6 Threshold data 1 + +Threshold data is partitioned into two MEs to permit the set-by-create operation on all attributes, as limited by OMCI message size. An instance of this managed entity, together with an optional instance of the threshold data 2 ME, contains threshold values for performance monitoring counters in history data managed entities. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity may be related to multiple instances of performance monitoring history data type managed entities. Managed entities that support PM functionality are listed in clause 7.3. + +Paired instances of threshold data 1 ME and threshold data 2 ME are implicitly linked together through a common ME ID. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. +(R, Set-by-create) (mandatory) (2 bytes) + +The following seven attributes specify threshold values for seven thresholded counters in associated PM history data MEs. The definition of each PM history ME includes a table that links each thresholded counter to one of these threshold value attributes. + +**Threshold value 1:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 2:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 3:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 4:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 5:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 6:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 7:** (R, W, Set-by-create) (mandatory) (4 bytes) + +#### *Actions* + +#### **Create, delete, get, set** + +#### *Notifications* + +None. + +### 9.12.7 Threshold data 2 + +Together with an instance of the threshold data 1 ME, an instance of this managed entity contains threshold values for the performance monitoring parameters maintained in one or more instances of history data managed entities. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +Refer to the relationships of the threshold data 1 ME. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Its value is the same as that of the paired threshold data 1 instance. (R, Set-by-create) (mandatory) (2 bytes) + +The following seven attributes specify threshold values for seven thresholded counters in associated PM history data MEs. The definition of each PM history ME includes a table that links each thresholded counter to one of these threshold value attributes. + +**Threshold value 8:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 9:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 10:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 11:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 12:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 13:** (R, W, Set-by-create) (mandatory) (4 bytes) + +**Threshold value 14:** (R, W, Set-by-create) (mandatory) (4 bytes) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.12.8 OMCI** + +This managed entity describes the ONT's general level of support for OMCI managed entities and messages. This ME is not included in MIB upload. + +#### *Relationships* + +One instance exists in the ONT. The ME entities are related to the OMCI entity. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**ME type table:** This attribute lists the ME classes supported by the ONT. Each entry contains the managed entity class value (see Table 11-2) of a managed entity. For MEs inherited from G.983.2 B-PON, the most significant byte is zero. (R) (mandatory) (2N bytes, where N is the number of entries in the list) + +**Message type table:** This attribute is a list of message types supported by the ONT. Each entry contains the message type of an OMCI message (see Table 11-1). (R) (mandatory) (M bytes, where M is the number of entries in the list) + +#### *Actions* + +**Get, get next** + +#### *Notifications* + +None. + +### 9.12.9 Managed entity + +The managed entity ME describes the details of each managed entity that is supported by the ONT. This ME is not included in MIB upload. + +#### *Relationships* + +One or more managed entities are related to the OMCI object entity. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Its value is equal to the managed entity type value, and is the same as the code found in the ME type table attribute of the OMCI ME and Table 11-2. (R) (mandatory) (2 bytes) +- Name:** This attribute contains a 25-byte ASCII coded mnemonic tag for the ME type. Strings shorter than 25 bytes are padded with null characters. (R) (mandatory) (25 bytes) +- Attributes table:** This table contains pointers to the attribute MEs that describe each of these ME's attributes. +NOTE – The managed entity ID attribute is not included in the list, since the type of this attribute is fixed. +(R) (mandatory) (2X bytes, where X is the number of entries in the table) +- Access:** This attribute represents who creates this ME. The following code points are defined: +1 Created by the ONT. +2 Created by the OLT. +3 Created by both ONT and OLT. +(R) (mandatory) (1 byte) +- Alarms table:** This attribute lists the alarm codes that are supported. (R) (mandatory) (Y bytes, where Y is the number of entries in the table) +- AVCs table:** This attribute lists the AVCs that are supported. (R) (mandatory) (Z bytes, where Z is the number of entries in the table) +- Actions:** This attribute lists the action codes supported on this object, formatted as a bit map. The action codes are the message types from Table 11-1. The least significant bit represents action 0, and so on. (R) (mandatory) (4 bytes) +- Instances table:** This attribute is a list of pointers to all instances of this ME. (R) (mandatory) (2V bytes, where V is the number of entries in the table) +- Support:** This attribute represents support capability of this ME in the ONT's implementation. This attribute does not declare if the OMCI implementation complies with the recommendations, but if it complies with the OMCI declaration itself. The following code points are defined: +1 Supported (supported as defined in this object). +2 Unsupported (OMCI returns error code if accessed). +3 Partially supported (some aspects of ME supported). +4 Ignored (OMCI supported, but underlying function is not). +(R) (mandatory) (1 byte) + +*Actions* + +##### **Get, get next** + +*Notifications* + +None. + +### **9.12.10 Attribute** + +This managed entity describes a particular attribute type that is supported by the ONT. This ME is not included in MIB upload. + +*Relationships* + +One or more attribute entities are related to each ME entity. More than one ME entity can refer to a given attribute entity. + +*Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This number is the same that appears in the attributes table in the managed entity ME. Only one instance of each unique attribute need be created. The ONT can assign attribute numbering as it pleases, out of the pool of 64K ids; however, it is suggested that the numbering follow a rational scheme to aid human readability. (R) (mandatory) (2 bytes) + +**Name:** This attribute contains a 25-byte mnemonic tag for the attribute. Strings shorter than 25 bytes are padded with null characters. (R) (mandatory) (25 bytes) + +**Size:** This attribute contains the size of the attribute, in bytes. The value 0 indicates that the attribute can have a variable/unknown size. (R) (mandatory) (2 bytes) + +**Access:** This attribute represents the OMCI access characteristics of the attribute. The following code points are defined: + +- 1 Read. +- 2 Write. +- 3 Read, write. +- 5 Read, Set-by-create. +- 6 Write, Set-by-create. +- 7 Read, write, Set-by-create. + +(R) (mandatory) (1 byte) + +**Format:** This attribute represents the format of the attribute. The following code points are defined: + +- 1 Pointer. +- 2 Bit field. +- 3 Signed integer. +- 4 Unsigned integer. +- 5 String. +- 6 Enumeration (that is, a set of defined code points). +- 7 Table. + +(R) (mandatory) (1 byte) + +**Lower limit:** This attribute provides the lowest value for the attribute. Valid for numeric types (pointer, signed integer, unsigned integer) only. For attributes smaller than 4 bytes, the desired numeric value is expressed in 4-byte representation (e.g., the signed one-byte integer 0xFE is expressed as 0xFFFF FFFE; the unsigned one-byte integer 0xFE is expressed as 0x0000 00FE). (R) (mandatory) (4 bytes) + +**Upper limit:** This attribute provides the highest value for the attribute. It has the same validity and format as the lower limit attribute. (R) (mandatory) (4 bytes) + +**Bit field:** This attribute is a mask of the supported bits in a bit field attribute. Valid for bit field type only. A 1 in any position signifies that its code point is supported, while 0 indicates not supported. For bit fields smaller than 4 bytes, the attribute is aligned at the least significant end of the mask. (R) (mandatory) (4 bytes) + +**Code points table:** This attribute lists the code points supported by an enumerated attribute. (R) (mandatory) (2Q bytes, where Q is the number of entries in the table) + +**Support:** This attribute represents the level of support of the attribute (same notation as the attribute of the same name in the ME). The following code points are defined: + +- 1 Fully supported (supported as defined in this object). +- 2 Unsupported (OMCI returns an error code if accessed). +- 3 Partially supported (some aspects of attribute supported). +- 4 Ignored (OMCI supported, but underlying function is not). + +(R) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, get next** + +#### *Notifications* + +None. + +### **9.12.11 Octet string** + +The octet string is modelled on the large string managed entity. The large string is constrained to printable characters because it uses null as a trailing delimiter. The octet string has a length attribute and is therefore suitable for arbitrary sequences of bytes. + +Instances of this managed entity are created and deleted by the OLT. To use this managed entity, the OLT instantiates the octet string ME and then points to the created ME from other ME instances. Systems that maintain the octet string should ensure that the octet string ME is not deleted while it is still linked. + +#### *Relationships* + +An instance of this ME may be cited by any ME that requires an octet string that can exceed 25 bytes in length. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. The values 0 and 0xFFFF are reserved. (R, Set-by-create) (mandatory) (2 bytes) + +**Length:** This attribute specifies the number of octets that comprise the sequence of octets. This attribute defaults to 0 to indicate no octet string is defined. The maximum value of this attribute is 375 (15 parts, 25 bytes each). (R, W) (mandatory) (2 bytes) + +Fifteen additional attributes are defined below; they are identical. The octet string is simply divided into as many parts as necessary, starting at part 1 and left justified. + +**Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11, Part 12, Part 13, Part 14, Part 15:** (R, W) (part 1 mandatory, others optional) (25 bytes \* 15 attributes) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +None. + +### **9.12.12 General purpose buffer** + +This managed entity is created by the OLT when needed to store the results of an operation, such as a test command, that needs to return a block of data of indeterminate size. The buffer is retrieved with get next operations, since its size is not known *a priori*. An instance of this ME is created and deleted by the OLT, and typically made known to an ONT ME or action through a pointer. + +The ME is defined as generically as possible, such that it can be used for other applications that may not initially be apparent, such as logging. The format of its contents is specific to each application, and is documented there. + +The general purpose buffer is neither captured in a MIB upload, nor retained in non-volatile ONT memory. + +#### *Relationships* + +Through a pointer, the OLT may associate a general purpose buffer with an ME and/or an operation that has a need to create large or indeterminate blocks of data for subsequent upload. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Maximum size:** The ONT determines the actual size of the buffer table in the process of capturing the data directed to it. The maximum size attribute permits the OLT to restrict the maximum size of the buffer table. The default value 0 indicates that the OLT imposes no limit on the size; it is recognized that ONT implementations will impose their own limits. The ONT will not create a buffer table larger than this value. If the ONT cannot allocate enough memory to accommodate this size, it should deny the ME creation action or a write operation that attempts to expand an existing ME. (R, W, Set-by-create) (optional) (4 bytes) + +**Buffer table:** This attribute is an octet string that contains the result of some operation performed on the ONT. The exact content depends on the operation, and is documented with the definition of each operation. (R) (mandatory) (N bytes) + +#### *Actions* + +**Create, delete, get, get next** + +#### Notifications + +##### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Reserved | | +| 2 | Buffer table | This AVC indicates that the ONT has completed writing the buffer, and thereby signals the OLT that the operation is complete and the buffer is available for upload | +| 3..16 | Reserved | | + +## 9.13 Miscellaneous services + +### 9.13.1 Physical path termination point video UNI + +This managed entity represents an RF video UNI in the ONT, where physical paths terminate and physical path level functions are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has RF video UNI ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of video UNI type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of video UNI type. Note that the installation of a plug-and-play card may indicate the presence of video ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies video ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect a video circuit pack, nor is it equipped with a video circuit pack. + +#### Relationships + +One or more instances of this managed entity is associated with an instance of a real or virtual circuit pack classified as video type. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +**Power control:** This attribute controls whether power is provided to an external equipment over the video PPTP. Value 1 enables power over coaxial cable. The default value 0 disables power feed. (R, W) (optional) (1 byte) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of video UNI | +| 3 | ARC | ARC timer expiration | +| 4..5 | N/A | | +| 6..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|----------|------------------------|-------------------------------------| +| 0 | Video-LOS | No signal at the video UNI | +| 1 | Video-OOR-low | RF output below rated value | +| 2 | Video-OOR-high | RF output above rated value | +| 3..207 | Reserved | Reserved for vendor-specific alarms | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.13.2 Physical path termination point video ANI** + +This managed entity represents an RF video ANI in the ONT, where physical paths terminate and physical path level functions are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has video ANI ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of video ANI type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of video ANI type. Note that the installation of a plug-and-play card may indicate the presence of video ANI ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies video ANI ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect a video ANI circuit pack, nor is it equipped with a video ANI circuit pack. + +#### *Relationships* + +An instance of this managed entity is associated with each instance of a real or preprovisioned video ANI port. + +#### *Attributes* + +| | | +|------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the ANI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) | +| Administrative state: | This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this managed entity are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) | +| Operational state: | This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) | +| ARC: | See clause I.1.8. (R, W) (optional) (1 byte) | +| ARC interval: | See clause I.1.8. (R, W) (optional) (1 byte) | +| Frequency range low: | This attribute indicates the lower of the two possible frequency ranges supported. Different frequency ranges are indicated by code points:
0 No low band.
1 50..550 MHz.
2 50..750 MHz.
3 50..870 MHz.
4..255 Reserved.
(R) (mandatory) (1 byte) | +| Frequency range high: | This attribute indicates the higher of the two frequency ranges supported. Different frequency ranges are indicated by code points:
0 No high band.
1 550..750 MHz.
2 550..870 MHz.
3 950..2050 MHz.
4 2150..3250 MHz.
5 950..3250 MHz.
6..255 Reserved.
(R) (mandatory) (1 byte) | +| Signal capability: | This attribute indicates the capability of the ONT to measure the video signal level. Capabilities are indicated by code points:
0 No signal level capability.
1 Total optical power level.
2 Fixed frequency pilot tone power level.
3 Total optical power level and fixed frequency pilot tone power level. | + +- 4 Variable frequency pilot tone power level. +- 5 Total optical power level and variable frequency pilot tone power level. +- 6 Broadband RF power level. +- 7 Total optical power level and broadband RF power level. +- 8..255 Reserved. + +(R) (mandatory) (1 byte) + +**Optical signal level:** This attribute is an unsigned integer that returns the current measurement of the total optical signal level. The unit of this attribute is dB $\mu$ W optical. + +- If signal capability = 0, 2, 4 or 6, this attribute is undefined. +- If signal capability = 1, 3, 5 or 7, this attribute describes the total optical power that is generating photocurrent on the receiver. + +(R) (optional) (1 byte) + +**Pilot signal level:** This attribute indicates the current measurement of the pilot signal level or broadband RF level. The unit of this attribute is dB $\mu$ V at the RF video service port. + +- If signal capability = 0 or 1, then this attribute is undefined. +- If signal capability = 2, 3, 4 or 5, this attribute reports the pilot signal level at the output of the video UNI. +- If signal capability = 6 or 7, this attribute reports the total RF power level at the output of the video UNI. + +(R) (optional) (1 bytes) + +**Signal level min:** This attribute indicates the minimum optical RF power per channel that results in a CNR of 47 dBc for a channel of 4.5 MHz bandwidth at a receive optical power of -5 dBm. The unit of this attribute is dB $\mu$ W optical. (R) (mandatory) (1 byte) + +**Signal level max:** This attribute indicates the maximum optical RF power per channel that results in a CTB of -57 dBc for an 80-channel ensemble of carriers at a per-channel optical modulation index of 3.5%. The unit of this attribute is dB $\mu$ W optical. (R) (mandatory) (1 byte) + +**Pilot frequency:** This attribute specifies the frequency of the pilot channel receiver. The unit of this attribute is Hz. + +- If signal capability = 0, 1, 6 or 7, this attribute is undefined. +- If signal capability = 2 or 3, this attribute is functionally read only. +- If signal capability = 4 or 5, this attribute is read-write. + +(R, W) (optional) (4 bytes) + +**AGC mode:** This attribute allows the discovery and configuration of the ONT's AGC capabilities. The attribute contains a codepoint for several AGC types. The ONT displays the currently used AGC mode. The OLT can discover new modes via the set command; the ONT denies attempts to set an unsupported mode. The code points are: + +| | | +|--------|-------------------| +| 0 | No AGC. | +| 1 | Broadband RF AGC. | +| 2 | Optical AGC. | +| 3..255 | Reserved. | + +(R, W) (optional) (1 byte) + +**AGC setting:** This attribute indicates the measurement offset that the ONT should use in AGC. The attribute has a step size of 0.1 dB, represented as a signed integer. + +The theoretical nominal RF signal is 80 channels of NTSC video, each having a per-channel optical modulation index of 3.5%. An ONT presented with such a signal should produce its specified output when this attribute is set to zero. + +If total optical power is used for AGC, this attribute provides the OMI offset for any NTSC carriers present from the theoretical 3.5% value. For example, if the actual signal uses an OMI of 7.0% per channel (3 dB higher), then the ONT should be given an AGC setting of 30 (coded 0x1E). + +If broadband RF power is used for AGC, this attribute provides the total power offset for any NTSC carriers present from the theoretical 80 channel value. For example, if an actual signal contains 40 NTSC channels (3 dB lower), then the ONT should be given an AGC setting of -30 (coded 0xE2). + +(R, W) (optional) (1 byte) + +**Video lower optical threshold:** This attribute specifies the optical level used to declare the video OOR low alarm. Valid values are -12 to +6 dBm in 0.1 dB increments, represented as a 2s complement integer (coding -120 to +60, where 0x00 = 0 dBm, 0x88 = -12.0 dBm, etc.). Upon ME instantiation, the ONT sets this attribute to 0xA1 (-9.5 dBm). (R, W) (optional) (1 byte) + +NOTE – Because the power measurement returned in the optical signal level attribute has a resolution of 1 dB, it is possible that the measured value could appear to be in-range, even though an out-of-range alarm has been declared against a threshold with 0.1 dB resolution. + +**Video upper optical threshold:** This attribute specifies the optical level used to declare the video OOR high alarm. Valid values are -12 to +6 dBm in 0.1 dB increments, represented as a 2s complement integer (coding -120 to +60, 0x00 = 0 dBm, 0x88 = -12.0 dBm, etc.). Upon ME instantiation, the ONT sets this attribute to 0x19 (+2.5 dBm). (R, W) (optional) (1 byte) + +*Actions* + +**Get, set** + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of video ANI | +| 3 | ARC | ARC timer expiration | +| 4..16 | N/A | | + +##### Alarm + +| Number | Alarm | Description | +|----------|------------------------|----------------------------------------------------------| +| 0 | Video LOS | No signal at the video ANI | +| 1 | Video OOR low | Signal strength below lower optical threshold (optional) | +| 2 | Video OOR high | Signal strength above upper optical threshold (optional) | +| 3..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.13.3 Physical path termination point LCT UNI + +This managed entity represents the local craft terminal UNI, where physical paths terminate and physical path level functions are performed. + +The ONT automatically creates an instance of this managed entity per port: + +- When the ONT has LCT ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of LCT type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of LCT type. Note that the installation of a plug-and-play card may indicate the presence of LCT ports via equipment ID as well as its type, and indeed may cause the ONT to instantiate a port mapping package that specifies LCT ports. + +The ONT automatically deletes instances of this managed entity when a cardholder is neither provisioned to expect an LCT circuit pack, nor is it equipped with an LCT circuit pack. + +LCT instances are not reported during a MIB upload. + +#### Relationships + +An instance of this managed entity is associated with an instance of a real or virtual circuit pack managed entity classified as LCT type. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. This two-byte number indicates the physical position of the UNI. The first byte is the slot id (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions of this UNI are blocked. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +*Actions* + +**Get, set** + +*Notifications* + +None. + +### **9.13.4 Interworking VCC termination point** + +An instance of this managed entity represents a point in the ONT where the interworking of a service or underlying physical infrastructure (e.g., ADSL) to an ATM layer takes place. At this point, ATM cells are generated from a bit stream (e.g., Ethernet) or a bit stream is re-constructed from ATM cells. + +Instances of this managed entity are created and deleted by the OLT. + +*Relationships* + +One instance of this managed entity exists for each occurrence of transformation of a data stream into ATM cells and vice versa. + +*Attributes* + +| | | +|------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. It must be unique over all interworking VCC and GEM interworking termination point MEs. (R, Set-by-create) (mandatory) (2 bytes) | +| VCI value: | This attribute identifies the VCI value associated with this interworking VCC termination point. (R, W, Set-by-create) (mandatory) (2 bytes) | +| VP network CTP connectivity pointer: | This attribute points to the VP network CTP associated with this interworking VCC termination point. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Interworking option: | Not used, should be set to 0. (R, W, Set-by-create) (mandatory) (1 byte) | +| Service profile pointer: | Not used, should be set to 0. (R, W, Set-by-create) (mandatory) (2 bytes) | +| AAL5 profile pointer: | This attribute points to an instance of the AAL5 profile. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Interworking termination point pointer: | Not used, should be set to 0. (R, W, Set-by-create) (mandatory) (2 bytes) | + +#### **AAL loopback configuration:** + +This attribute sets the ATM loopback configuration. All codepoints are retained for backward compatibility, but some are not expected to be needed in G-PON applications. + +- 0 No loopback. +- 1 Loopback 1, loopback of downstream traffic before FEC of AAL 1. +- 2 Loopback 2, loopback of downstream traffic after FEC of AAL 1. +- 3 Loopback after AAL, loopback of downstream traffic after any AAL. Loopback after AAL is depicted in Figure 9.13.4-1. + +![Diagram of AAL loopback configuration. It shows an ONT (Optical Network Terminal) connected to an xDSL UNI on the left and a PON (Passive Optical Network) on the right. Inside the ONT, there is an 'ATM interworking' block. A loopback path is shown as a curved arrow starting from the output of the ATM interworking block and returning to its input, labeled 'Loopback after AAL'. The connection between the ATM interworking block and the PON is labeled 'Ethernet over GEM'. The diagram is labeled G.984.4(08)_F9.13.4-1.](149b9a6fdf6e7b380be26a57031e0263_img.jpg) + +Diagram of AAL loopback configuration. It shows an ONT (Optical Network Terminal) connected to an xDSL UNI on the left and a PON (Passive Optical Network) on the right. Inside the ONT, there is an 'ATM interworking' block. A loopback path is shown as a curved arrow starting from the output of the ATM interworking block and returning to its input, labeled 'Loopback after AAL'. The connection between the ATM interworking block and the PON is labeled 'Ethernet over GEM'. The diagram is labeled G.984.4(08)\_F9.13.4-1. + +**Figure 9.13.4-1 – AAL loopback configuration** + +The default value of this attribute is 0. (R, W) (mandatory) (1 byte) + +**PPTP counter:** This value is the number of instances of PPTP managed entities associated with this instance of the interworking VCC termination point. (R) (optional) (1 byte) + +**Operational state:** This attribute indicates whether or not the managed entity is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +#### *Actions* + +**Create, delete, get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..8 | N/A | | +| 9 | Op state | Operational state change | +| 10..16 | Reserved | | + +##### **Alarm** + +| Number | Alarm | Description | +|--------|----------------------------|-----------------------------------------------------------------------------------------------------------| +| 0 | End-to-end VC AIS LMIR | End-to-end VC-AIS receiving indication (optional) | +| 1 | End-to-end VC RDI LMIR | End-to-end VC-RDI receiving indication (optional) | +| 2 | End-to-end VC AIS LMIG | End-to-end VC-AIS generation indication (optional) | +| 3 | End-to-end VC RDI LMIG | End-to-end VC-RDI generation indication (optional) | +| 4 | Segment loss of continuity | Loss of continuity detected when the interworking VCC termination point is a segment end point (optional) | + +##### Alarm + +| Number | Alarm | Description | +|----------|-------------------------------|----------------------------------------------------------------------------------| +| 5 | End-to-end loss of continuity | Loss of continuity detected at the interworking VCC termination point (optional) | +| 6 | CSA | Cell starvation alarm | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.13.5 AAL 5 profile + +NOTE – Except for its name, this managed entity is identical to the AAL 5 profileB-PON defined in [ITU-T G.983.2]. + +This managed entity organizes data that describe the AAL type 5 processing functions of the ONT. It is used with the interworking VCC termination point managed entity. + +This managed entity is created and deleted by the OLT. + +#### Relationships + +An instance of this managed entity may be associated with zero or more instances of the interworking VCC termination point. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. (R, Set-by-create) (mandatory) (2 bytes) + +**Max CPCS PDU size:** This attribute specifies the maximum CPCS PDU size to be transmitted over the connection in both upstream and downstream directions. (R, W, Set-by-create) (mandatory) (2 bytes) + +**AAL mode:** This attribute specifies the AAL mode: +0 Message assured. +1 Message unassured. +2 Streaming assured. +3 Streaming non-assured. +(R, W, Set-by-create) (mandatory) (1 byte) + +**SSCS type:** This attribute specifies the SSCS type for the AAL. Valid values are: +0 Null. +1 Data SSCS based on SSCOP, assured operation. +2 Data SSCS based on SSCOP, non-assured operation. +3 Frame relay SSCS. +(R, W, Set-by-create) (mandatory) (1 byte) + +#### Actions + +##### Create, delete, get, set + +#### Notifications + +None. + +### 9.13.6 AAL 5 performance monitoring history data + +NOTE – Except for its name, this managed entity is substantially identical to the AAL 5 protocol monitoring history dataB-PON defined in [ITU-T G.983.2]. + +This managed entity collects performance monitoring data as a result of performing segmentation and reassembly (SAR) and convergence sublayer (CS) level protocol monitoring. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.1.9. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of an interworking VCC termination point that represents AAL 5 functions. + +#### *Attributes* + +| | | +|----------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the interworking VCC termination point. (R, Set-by-create) (mandatory) (2 bytes) | +| Interval end time: | This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) | +| Threshold data 1/2 id: | This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Sum of invalid CS field errors: | This attribute counts the sum of invalid convergence sublayer (CS) field errors. For AAL type 5, this attribute is a single count of the number of CS PDUs discarded due to one of the following error conditions: invalid common part indicator (CPI), oversized received SDU, or length violation. (R) (mandatory) (4 bytes) | +| CRC violations: | This attribute counts CRC violations detected on incoming SAR PDUs. (R) (mandatory) (4 bytes) | +| Reassembly timer expirations: | This attribute counts reassembly timer expirations. (R) (mandatory if reassembly timer is implemented) (4 bytes) | +| Buffer overflows: | This attribute counts the number of times there was not enough buffer space for a reassembled packet. (R) (mandatory) (4 bytes) | +| Encap protocol errors: | This attribute counts the number of times that [IETF RFC 1483] encapsulation protocol detected a bad header. (R) (mandatory) (4 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|------------------------------|------------------------------------| +| 0 | Invalid fields | 1 | +| 1 | CRC violation | 2 | +| 2 | Reassembly timer expirations | 3 | +| 3 | Buffer overflows | 4 | +| 4 | Encap protocol errors | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.13.7 Video return path service profile + +This managed entity models an RF video return path. The ONT creates an instance autonomously if it supports this function. + +Further description of the video return path (VRP) feature appears in Appendix IV, that defines transport methods required to support the video return path function. This includes a brief description of the relevant aspects of the two return path specifications supported. It also includes formatting for carriage of VRP data over the PON data path. + +#### Relationships + +One instance of this managed entity may exist for each ONT. + +#### Attributes + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. There is one instance, number 0. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this managed entity. When the administrative state is set to lock, all user functions are blocked, and alarms, TCAs and AVCs for this managed entity and all dependent managed entities are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute reports whether the managed entity is currently capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause I.1.8. (R, W) (optional) (1 byte) + +**ARC interval:** See clause I.1.8. (R, W) (optional) (1 byte) + +- VRP mode:** This attribute specifies the format to be used for the VRP service: +- 0 Mode 1, SCTE 55-1 (256 kbit/s data rate, 62 byte PDUs, preceded by the unique word 0xCC CC CC 00). (mandatory) + - 1 Mode 2, SCTE 55-2 (256 kbit/s data rate, 59 byte PDUs, preceded by the unique word 0xCC CC CC 0D). (optional) + - 2 Mode 2, SCTE 55-2 (1.544 Mbit/s data rate, 59 byte PDUs, preceded by the unique word 0xCC CC CC 0D). (mandatory) + - 3 Mode 2, SCTE 55-2 (3.088 Mbit/s data rate, 59 byte PDUs, preceded by the unique word 0xCC CC CC 0D). (optional) + - 4..255 Reserved. +- (R, W) (mandatory) (1 byte) +- VRP frequency lower bound:** This attribute reports the VRP tuning range lower bound, in units of Hertz. (R) (mandatory) (4 bytes) +- VRP frequency upper bound:** This attribute reports the VRP tuning range upper bound, in units of Hertz. (R) (mandatory) (4 bytes) +- VRP frequency used:** This attribute specifies the VRP tuner frequency to use, in units of Hertz. (R, W) (mandatory) (4 bytes) +- Mode 1 physical layer configuration mode:** This attribute controls the physical layer configuration to be used in mode 1. The attribute is bit mapped, as follows: +- Bit 16 (MSB) DQPSK mode; 0 = default mode, 1 = alternate mode. + - Bit 15..9 Reserved. + - Bit 8 Randomizer stage 6 preload. + - Bit 7 Randomizer stage 7 preload. + - Bit 6 Randomizer stage 8 preload. + - Bit 5 Randomizer stage 9 preload. + - Bit 4 Randomizer stage 10 preload. + - Bit 3 Randomizer stage 11 preload. + - Bit 2 Randomizer stage 12 preload. + - Bit 1 Randomizer stage 13 preload. +- (R, W) (mandatory) (2 bytes) + +#### *Actions* + +#### **Get, set** + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state change | +| 3 | ARC | ARC timer expiration | +| 4..9 | N/A | | +| 10..16 | Reserved | | + +##### Alarm + +| Number | Event | Description | +|----------|------------------------|-----------------------------------------------------------------------------------------------------------------------------| +| 0 | Frequency mismatch | Frequency set by OLT is outside the capabilities of this ONT, or a frequency that is not on the standardized frequency plan | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.13.8 Video return path performance monitoring history data + +#### *Relationships* + +One instance of this managed entity may exist for each ONT. It is created by the OLT. + +#### *Attributes* + +- Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the video return path service profile. (R) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 and 2 managed entities that contain PM threshold values. (R, W, Set-by-create) (mandatory) (2 bytes) +- Rx total bursts:** This attribute counts the total number of bursts detected. (R) (optional) (4 bytes) +- Rx good bursts:** This attribute counts bursts detected and received correctly. (R) (optional) (4 bytes) +- Rx FEC corrected bursts:** This attribute counts bursts detected with errors, but which were successfully corrected using FEC. (R) (optional) (4 bytes) +- Rx missed bursts:** This attribute counts bursts detected that were not received correctly (e.g., errors that were FEC uncorrectable). (R) (optional) (4 bytes) +- Rx min power:** This attribute is a low water mark that reports the lowest power level of all bursts received in the current interval, in units of dBmV. (R) (optional) (1 byte) +- Rx max power:** This attribute is a high water mark that reports the highest power level of all bursts received in the current interval, in units of dBmV. (R) (optional) (1 byte) +- Rx current power:** This attribute reports the power level of the latest burst received, in units of dBmV. (R) (optional) (1 byte) +- Rx FEC corrected symbols:** This attribute counts the number of symbols that were corrected through the use of FEC. It provides an indicator of the bit error rate of the link. (R) (optional) (4 bytes) + +#### *Actions* + +**Create, delete, set, get** + +**Get current data (optional)** + +#### Notifications + +#### Threshold crossing alert + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Rx total bursts | 1 | +| 1 | Rx good bursts | 2 | +| 2 | Rx FEC corrected bursts | 3 | +| 3 | Rx missed bursts | 4 | +| 4 | Rx min power | 5 | +| 5 | Rx max power | 6 | +| 6 | Rx current power | 7 | +| 7 | Rx FEC corrected symbols | 8 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.13.9 VP network CTP-G + +This managed entity represents the termination of VP links on an ONT. It aggregates connectivity functionality from the network view and alarms from the network element view as well as artefacts from trails. Instances of this managed entity are created and deleted by the OLT. + +An instance of the VP network CTP-G managed entity can be deleted only when no ATM interworking VCC termination point is associated with it. It is the responsibility of the OLT to ensure that this condition is met. + +#### Relationships + +Zero or more instances of the VP network CTP-G managed entity may exist for each instance of the interworking VCC termination point managed entity. + +#### Attributes + +| | | +|-------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity id: | This attribute uniquely identifies each instance of this managed entity. It must be unique over all GEM port network CTP and VP network CTP-G MEs. (R, Set-by-create) (mandatory) (2 bytes) | +| VPI value: | This attribute identifies the VPI value associated with the VP link being terminated. (R, W, Set-by-create) (mandatory) (2 bytes) | +| UNI pointer: | This pointer indicates the xDSL physical path termination point UNI associated with this VP termination point. The bearer channel may be indicated by the two most significant bits of the pointer. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Direction: | This attribute specifies whether the VP link is used for UNI-to-ANI (value 1), ANI-to-UNI (value 02), or bidirectional (value 3) connection. (R, W, Set-by-create) (mandatory) (1 byte) | +| Priority queue pointer for downstream: | Not used, should be set to 0. (R, W, Set-by-create) (mandatory) (2 bytes) | +| Traffic management pointer for upstream: | Not used, should be set to 0. (R, W, Set-by-create) (mandatory) (2 bytes) | + +**Traffic descriptor profile pointer:** Not used, should be set to 0. (R, W, Set-by-create) (optional) (2 bytes) + +**UNI counter:** Not used, should be set to 0. (R) (optional) (1 byte) + +#### *Actions* + +##### **Create, delete, get, set** + +#### *Notifications* + +##### **Alarm** + +| Number | Alarm | Description | +|----------|-------------------------------|------------------------------------------------------------------------------------------------------------------------| +| 0 | VP AIS LMIR | VP-AIS receiving indication (optional) | +| 1 | VP RDI LMIR | VP-RDI receiving indication (optional) | +| 2 | VP AIS LMIG | VP-AIS generation indication (optional) | +| 3 | VP RDI LMIG | VP-RDI generation indication (optional) | +| 4 | Segment loss of continuity | Loss of continuity is detected when the VP network CTP-G is a segment end point (optional) | +| 5 | End-to-end loss of continuity | Loss of continuity can be detected when the VP network CTP-G supports an interworking VCC termination point (optional) | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.13.10 VP performance monitoring history data** + +This managed entity collects performance monitoring data associated with a VP network CTP-G. Instances of this managed entity are created and deleted by the OLT. + +#### *Relationships* + +An instance of this managed entity is associated with an instance of the VP network CTP-G managed entity. The performance of upstream ATM flows is reported. + +#### *Attributes* + +**Managed entity id:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the VP network CTP-G. (R, Set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) + +**Lost C = 0 + 1 cells:** This attribute counts background cell loss. It cannot distinguish between cells lost because of header bit errors, ATM-level header errors, cell policing, or buffer overflows. It records only loss of information, independent of the priority of the cell. (R) (mandatory) (2 bytes) + +| | | +|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Lost C = 0 cells: | This attribute counts background cell loss. It cannot distinguish between cells lost because of header bit errors, ATM-level header errors, cell policing or buffer overflows. It records only loss of high priority cells. (R) (mandatory) (2 bytes) | +| Misinserted cells: | This attribute counts cells that are misrouted to a monitored VP. (R) (mandatory) (2 bytes) | +| Transmitted C = 0 + 1 cells: | This attribute counts cells originated by the transmitting end point (i.e., backward reporting is assumed). (R) (mandatory) (5 bytes) | +| Transmitted C = 0 cells: | This attribute counts high priority cells originated by the transmitting end point (i.e., backward reporting is assumed). (R) (mandatory) (5 bytes) | +| Impaired blocks: | This severely errored cell block counter is incremented whenever one of the following events takes place: the number of misinserted cells reaches its threshold, the number of bipolar violations reaches its threshold, or the number of lost cells reaches its threshold. Threshold values are based on vendor-operator negotiation. (R) (mandatory) (2 bytes) | + +#### *Actions* + +**Create, delete, get, set** + +**Get current data (optional)** + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute # (Note) | +|--------|--------------------------|------------------------------------| +| 0 | Lost CLP = 0 + 1 cells | 1 | +| 1 | Lost CLP = 0 cells | 2 | +| 2 | Misinserted cells | 3 | +| 3 | Impaired blocks | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +# **10 ONT management and control channel (OMCC)** + +A GEM connection shall be provisioned for the OMCC (the use of ATM mode is deprecated). [ITU-T G.984.3] specifies a PLOAM message that activates a PortID between the OLT and ONT processors. The PortID value for the management channel of each ONT is programmed by the OLT using this message. A grant flow must be allocated by the MAC layer of the OLT for upstream OMCC traffic of each ONT. + +The following performance requirements related to the OMCC are considered with input from operators: + +- The upstream traffic on each OMCC should not exceed x bandwidth, where x is based on the operator's requirement. +- An upstream OMCC packet should always be put in the high priority queue; the constraints on the downstream OMCC packets are out of the scope of this Recommendation, as this is completely under control of the OLT. + +- c) Message response time: The system should support response times that do not exceed one second for high priority protocol handling messages and three seconds for low priority protocol handling messages. + +# 11 ONT management and control protocol + +## 11.1 ONT management and control protocol packet format + +### 11.1.1 Introduction + +In GEM mode, each ONT management and control protocol packet is encapsulated directly in a GEM packet. The packet format is shown in Figure 11.1.1-1. Packet contents reflect the ATM heritage of B-PON; only the header is changed. The OMCI trailer is retained and used for its CRC. The following clauses discuss the details. + +| | | | | | | | +|-------------------------|-------------------------------------------------|--------------------------|-------------------------------|---------------------------------|--------------------------------|---------------------------| +| GEM header
(5 bytes) | Transaction correlation identifier
(2 bytes) | Message type
(1 byte) | Device identifier
(1 byte) | Message identifier
(4 bytes) | Message contents
(32 bytes) | OMCI trailer
(8 bytes) | +|-------------------------|-------------------------------------------------|--------------------------|-------------------------------|---------------------------------|--------------------------------|---------------------------| + +Figure 11.1.1-1 – ONT management and control protocol packet format + +### 11.1.2 GEM header + +The header contains the PortID (GEM mode) of the OMCC for the addressed ONT (see clause 10). The header PTI should equal 000 or 001 for GEM (as per normal fragmentation rules). + +### 11.1.3 Transaction correlation identifier + +The transaction correlation identifier is used to associate a request message with its response message. For request messages, the OLT selects any transaction identifier. A response message carries the transaction identifier of the message to which it is responding. The transaction identifier of event messages is 0x0000. + +As explained in clause 11.2, the most significant bit of the transaction correlation identifier indicates the priority of the message. The following coding is used: 0 = low priority, 1 = high priority. The OLT decides whether a command should be executed with low or high priority. + +The mechanism that the OLT uses to assign the rest of the bits of the transaction correlation identifier in an acknowledged command is not standardized and is left to the implementers. + +However, since the transaction correlation identifier is used to match a command from the OLT to the ONT with a response from the ONT to the OLT, some care is required in the choice of the transaction correlation identifier. The OLT must assign the transaction correlation identifier in such a way that, whenever it sends a command with a transaction correlation identifier that has been used before in another command to the same ONT, it is guaranteed with sufficiently high probability that no response for the first command will be received. + +### 11.1.4 Message type + +The message type field is subdivided into four parts. These are given in Figure 11.1.4-1. + +| | | | | | +|----|----|----|----|---| +| 8 | 7 | 6 | 5 | 1 | +| DB | AR | AK | MT | | + +Figure 11.1.4-1 – Message type field subdivision + +The most significant bit, bit 8, is reserved for the destination bit (DB). In the OMCI this bit is always 0. + +Bit 7, acknowledge request (AR), indicates whether or not the message requires an acknowledgement. If an acknowledgement is expected, this bit is set to 1. If no acknowledgement is expected, the coding of this bit is 0. Note that "acknowledge" means a response to an action request, not an acknowledgement at the link layer. + +Bit 6, acknowledgement (AK), indicates whether or not this message is an acknowledgement to an action request. If a message is an acknowledgement, this bit is set to 1. If the message is not a response, this bit is set to 0. + +Bits 5..1, message type (MT), indicate the message type. Codes 0 to 3 and 29 to 31 are reserved for future use. Codes 4 to 28 are used by this specification. Table 11-1 lists the message types that are defined. + +**Table 11-1 – OMCI message types** + +| MT | Type | Purpose | AK | Inc MIB data sync | +|----|----------------------------|--------------------------------------------------------------------------------------------|--------|-------------------| +| 4 | Create | Create a managed entity instance with its attributes | Yes | Yes | +| 5 | Create complete connection | Deprecated | – | – | +| 6 | Delete | Delete a managed entity instance | Yes | Yes | +| 7 | Delete complete connection | Deprecated | – | – | +| 8 | Set | Set one or more attributes of a managed entity | Yes | Yes | +| 9 | Get | Get one or more attributes of a managed entity | Yes | No | +| 10 | Get complete connection | Deprecated | – | – | +| 11 | Get all alarms | Latch the alarm statuses of all managed entities and reset the alarm message counter | Yes | No | +| 12 | Get all alarms next | Get the active alarm status of the next managed entity | Yes | No | +| 13 | MIB upload | Latch the MIB | Yes | No | +| 14 | MIB upload next | Get latched attributes of a managed entity instance | Yes | No | +| 15 | MIB reset | Clear the MIB and re-initialize it to its default and reset the MIB data sync counter to 0 | Yes | No | +| 16 | Alarm | Notification of an alarm | No | No | +| 17 | Attribute value change | Notification of an autonomous attribute value change | No | No | +| 18 | Test | Request a test on a specific managed entity | Yes | No | +| 19 | Start software download | Start a software download action | Yes | Yes | +| 20 | Download section | Download a section of a software image | Yes/No | No | +| 21 | End software download | End of a software download action | Yes | Yes | +| 22 | Activate software | Activate the downloaded software image | Yes | Yes | +| 23 | Commit software | Commit the downloaded software image | Yes | Yes | +| 24 | Synchronize Time | Synchronize the time between OLT and ONT | Yes | No | + +**Table 11-1 – OMCI message types** + +| MT | Type | Purpose | AK | Inc MIB data sync | +|----|------------------|--------------------------------------------------------------------------------------|-----|-------------------| +| 25 | Reboot | Reboot ONT or circuit pack | Yes | No | +| 26 | Get next | Get the latched attribute values of the managed entity within the current snapshot | Yes | No | +| 27 | Test result | Notification of test result that is initiated by "test" | No | No | +| 28 | Get current data | Get current counter value associated with one or more attributes of a managed entity | Yes | No | + +NOTE – The "download section" action is only acknowledged for the last section within a window. See clause I.2.15 of [ITU-T G.983.2]. + +### **11.1.5 Device identifier** + +For systems based on this Recommendation, this field is defined as 0x0A. + +### **11.1.6 Message identifier** + +The message identifier consists of four bytes. The first, most significant, two bytes of the message identifier field are used to indicate which managed entity is the target of the action specified in the message type. The maximum number of possible managed entities is thus 65535. The least significant two bytes of this message identifier field are used to identify the managed entity instance. The number of bytes for each managed entity instance is defined in clause 9. The summation of the number of bytes in the message identifier field and the number of bytes available in the message contents field shall be 36 bytes because the ONT management and control protocol packet format is 53 bytes long. + +Table 11-2 gives the managed entities and their class values in the OMCI. Depending on the managed entity, there will be only one (e.g., ONT-G) or several (e.g., MAC bridge port config data) instances in an ONT. Note that this table contains all the managed entities ever standardized for OMCI, including G.983 series and ATM features now deprecated, because all these class values will remain reserved forever. The class values defined in the G.983-series were only one byte, and so they are padded with a leading 0x00 byte to make them two-byte values usable in G-PON. + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|----------------------------|-----------------------------------------| +| 1 | ONT B-PON | +| 2 | ONT data | +| 3 | PON IF line cardholder | +| 4 | PON IF line card | +| 5 | Cardholder | +| 6 | Circuit pack | +| 7 | Software image | +| 8 | UNI B-PON | +| 9 | TC Adapter B-PON | +| 10 | Physical path termination point ATM UNI | + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|-------------------------------------------------------------| +| 11 | Physical path termination point Ethernet UNI | +| 12 | Physical path termination point CES UNI | +| 13 | Logical N x 64 kbit/s sub-port connection termination point | +| 14 | Interworking VCC termination point | +| 15 | AAL1 profile b-PON | +| 16 | AAL5 profile | +| 17 | AAL1 protocol monitoring history data B-PON | +| 18 | AAL5 performance monitoring history data | +| 19 | AAL2 profile | +| 20 | -----(Intentionally left blank) | +| 21 | CES service profile-G | +| 22 | (Reserved) | +| 23 | CES physical interface performance monitoring history data | +| 24 | Ethernet performance monitoring history data | +| 25 | VP network CTP | +| 26 | ATM VP cross-connection | +| 27 | Priority queue B-PON | +| 28 | DBR/CBR traffic descriptor | +| 29 | UBR traffic descriptor | +| 30 | SBR1/VBR1 traffic descriptor | +| 31 | SBR2/VBR2 traffic descriptor | +| 32 | SBR3/VBR3 traffic descriptor | +| 33 | ABR traffic descriptor | +| 34 | GFR traffic descriptor | +| 35 | ABT/DT/IT traffic descriptor | +| 36 | UPC disagreement monitoring history data B-PON | +| 37 | -----(intentionally left blank) | +| 38 | ANI | +| 39 | PON TC adapter | +| 40 | PON physical path termination point | +| 41 | TC adapter protocol monitoring history data | +| 42 | Threshold data B-PON | +| 43 | Operator specific | +| 44 | Vendor specific | +| 45 | MAC bridge service profile | +| 46 | MAC bridge configuration data | +| 47 | MAC bridge port configuration data | + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|-------------------------------------------------------------| +| 48 | MAC bridge port designation data | +| 49 | MAC bridge port filter table data | +| 50 | MAC bridge port bridge table data | +| 51 | MAC bridge performance monitoring history data | +| 52 | MAC bridge port performance monitoring history data | +| 53 | Physical path termination point POTS UNI | +| 54 | Voice CTP | +| 55 | Voice PM history data | +| 56 | AAL2 PVC profile B-PON | +| 57 | AAL2 CPS protocol monitoring history data B-PON | +| 58 | Voice service profile | +| 59 | LES service profile | +| 60 | AAL2 SSCS parameter profile1 | +| 61 | AAL2 SSCS parameter profile2 | +| 62 | VP performance monitoring history data | +| 63 | Traffic scheduler | +| 64 | T-CONT buffer | +| 65 | UBR+ traffic descriptor | +| 66 | AAL2 SSCS protocol monitoring history data B-PON | +| 67 | IP port configuration data | +| 68 | IP router service profile | +| 69 | IP router configuration data | +| 70 | IP router performance monitoring history data 1 | +| 71 | IP router performance monitoring history data 2 | +| 72 | ICMP performance monitoring history data 1 | +| 73 | ICMP performance monitoring history data 2 | +| 74 | IP route table | +| 75 | IP static routes | +| 76 | ARP service profile | +| 77 | ARP configuration data | +| 78 | VLAN tagging operation configuration data | +| 79 | MAC bridge port filter preassign table | +| 80 | Physical path termination point ISDN UNI | +| 81 | (Reserved) | +| 82 | Physical path termination point video UNI | +| 83 | Physical path termination point LCT UNI | +| 84 | VLAN tagging filter data | + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|--------------------------------------------------------| +| 85 | ONU B-PON | +| 86 | ATM VC cross-connection | +| 87 | VC network CTP B-PON | +| 88 | VC PM history data | +| 89 | Ethernet performance monitoring history data 2 | +| 90 | Physical path termination point video ANI | +| 91 | Physical path termination point 802.11 UNI | +| 92 | 802.11 station management data 1 | +| 93 | 802.11 station management data 2 | +| 94 | 802.11 general purpose object | +| 95 | 802.11 MAC and PHY operation and antenna data | +| 96 | 802.11 performance monitoring history data | +| 97 | 802.11 PHY FHSS DSSS IR tables | +| 98 | Physical path termination point xDSL UNI part 1 | +| 99 | Physical path termination point xDSL UNI part 2 | +| 100 | xDSL line inventory and status data part 1 | +| 101 | xDSL line inventory and status data part 2 | +| 102 | xDSL channel downstream status data | +| 103 | xDSL channel upstream status data | +| 104 | xDSL line configuration profile part 1 | +| 105 | xDSL line configuration profile part 2 | +| 106 | xDSL line configuration profile part 3 | +| 107 | xDSL channel configuration profile | +| 108 | xDSL subcarrier masking downstream profile | +| 109 | xDSL subcarrier masking upstream profile | +| 110 | xDSL PSD mask profile | +| 111 | xDSL downstream RFI bands profile | +| 112 | xDSL xTU-C performance monitoring history data | +| 113 | xDSL xTU-R performance monitoring history data | +| 114 | xDSL xTU-C channel performance monitoring history data | +| 115 | xDSL xTU-R channel performance monitoring history data | +| 116 | TC adaptor performance monitoring history data xDSL | +| 117 | Physical path termination point VDSL UNI | +| 118 | VDSL VTU-O physical data | +| 119 | VDSL VTU-R physical data | +| 120 | VDSL channel data | +| 121 | VDSL line configuration profile | + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|---------------------------------------------------------| +| 122 | VDSL channel configuration profile | +| 123 | VDSL band plan configuration profile | +| 124 | VDSL VTU-O physical interface monitoring history data | +| 125 | VDSL VTU-R physical interface monitoring history data | +| 126 | VDSL VTU-O channel performance monitoring history data | +| 127 | VDSL VTU-R channel performance monitoring history data | +| 128 | Video return path service profile | +| 129 | Video return path performance monitoring history data | +| 130 | 802.1p mapper service profile | +| 131 | OLT-G | +| 132 | Multicast interworking VCC termination point | +| 133 | ONT power shedding | +| 134 | IP host config data | +| 135 | IP host performance monitoring history data | +| 136 | TCP/UDP config data | +| 137 | Network address | +| 138 | VoIP config data | +| 139 | VoIP voice CTP | +| 140 | Call control performance monitoring history data | +| 141 | VoIP line status | +| 142 | VoIP media profile | +| 143 | RTP profile data | +| 144 | RTP performance monitoring history data | +| 145 | Network dial plan table | +| 146 | VoIP application service profile | +| 147 | VoIP feature access codes | +| 148 | Authentication security method | +| 149 | SIP config portal | +| 150 | SIP agent config data | +| 151 | SIP agent performance monitoring history data | +| 152 | SIP call initiation performance monitoring history data | +| 153 | SIP user data | +| 154 | MGC config portal | +| 155 | MGC config data | +| 156 | MGC performance monitoring history data | +| 157 | Large string | +| 158 | ONT remote debug | + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|------------------------------------------------------| +| 159 | Equipment protection profile | +| 160 | Equipment extension package | +| 161 | Port mapping package (B-PON only; use 297 for G-PON) | +| 162 | Physical path termination point MoCA UNI | +| 163 | MoCA Ethernet performance monitoring history data | +| 164 | MoCA interface performance monitoring history data | +| 165 | VDSL2 line configuration extensions | +| 166 | xDSL line inventory and status data part 3 | +| 167 | xDSL line inventory and status data part 4 | +| 168 | VDSL2 line inventory and status data part 1 | +| 169 | VDSL2 line inventory and status data part 2 | +| 170 | VDSL2 line inventory and status data part 3 | +| 171 | Extended VLAN tagging operation configuration data | +| 172..239 | Reserved for future B-PON managed entities | +| 240-255 | Reserved for vendor-specific managed entities | +| 256 | ONT-G | +| 257 | ONT2-G | +| 258 | ONU-G | +| 259 | ONU2-G | +| 260 | PON IF line card-G | +| 261 | PON TC adapter-G | +| 262 | T-CONT | +| 263 | ANI-G | +| 264 | UNI-G | +| 265 | ATM interworking VCC termination point | +| 266 | GEM interworking termination point | +| 267 | GEM port performance monitoring history data | +| 268 | GEM port network CTP | +| 269 | VP network CTP-G | +| 270 | VC network CTP-G | +| 271 | GAL TDM profile | +| 272 | GAL Ethernet profile | +| 273 | Threshold data 1 | +| 274 | Threshold data 2 | +| 275 | GAL TDM performance monitoring history data | +| 276 | GAL Ethernet performance monitoring history data | +| 277 | Priority queue-G | + +**Table 11-2 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|------------------------------------------------| +| 278 | Traffic scheduler-G | +| 279 | Protection data | +| 280 | GEM traffic descriptor | +| 281 | Multicast GEM interworking termination point | +| 282 | Pseudowire termination point | +| 283 | RTP pseudowire parameters | +| 284 | Pseudowire maintenance profile | +| 285 | Pseudowire performance monitoring history data | +| 286 | Ethernet flow termination point | +| 287 | OMCI | +| 288 | Managed entity | +| 289 | Attribute | +| 290 | Dot1X port extension package | +| 291 | Dot1X configuration profile | +| 292 | Dot1X performance monitoring history data | +| 293 | Radius performance monitoring history data | +| 294 | TU CTP | +| 295 | TU performance monitoring history data | +| 296 | Ethernet performance monitoring history data 3 | +| 297 | Port mapping package-G | +| 298 | Dot1 rate limiter | +| 299 | Dotlag maintenance domain | +| 300 | Dotlag maintenance association | +| 301 | Dotlag default MD level | +| 302 | Dotlag MEP | +| 303 | Dotlag MEP status | +| 304 | Dotlag MEP CCM database | +| 305 | Dotlag CFM stack | +| 306 | Dotlag chassis-management info | +| 307 | Octet string | +| 308 | General purpose buffer | +| 309 | Multicast operations profile | +| 310 | Multicast subscriber config info | +| 311 | Multicast subscriber monitor | +| 312 | FEC performance monitoring history data | +| 313-65279 | Reserved for future standardization | +| 65280-65535 | Reserved for vendor-specific use | + +### 11.1.7 Message contents + +The layout of the message contents field is message-specific. The detailed layout of all messages is given in Appendix II. + +### 11.1.8 OMCI trailer + +AAL5 trailer is reused in this field. The eight bytes of this field are used as follows: + +- a) The first two bytes are set to 0x0000 at the transmitter and ignored at the receiver (they correspond to CPCS-UU and CPI). +- b) The length of the CPCS-SDU field is set to 0x0028. +- c) The 32-bit CRC is as specified in [ITU-T I.363.5]. + +### 11.1.9 OMCI size limitations + +Due to the arrangement of the messages, the OMCI imposes limits on the size of the message payloads. Table 11-3 lists the important limits for both B-PON and G-PON usages of the OMCI. To enable re-use of managed entities over both B-PON and G-PON, it is important that all MEs are defined such that they fit into the G-PON limits. + +**Table 11-3 – OMCI protocol limitations** + +| Item | Limited by | G-PON limit | +|----------------------------------------------------------|---------------------------|-------------| +| Total size of Set-by-create attributes (including ME ID) | Create | 34 | +| Size of (R) or (R,W) simple attribute | Get response | 25 | +| Size of (R) or (R,W) table entry | Set | 30 | +| Total size of a get | Get response | 25 | +| Total size of a get current data | Get current data response | 25 | + +It is important that the OLT and ONT implementations take these limits into account. For example, it is very easy to form a 'get' command that asks the ONT to return more attributes than there is space in the response message. + +If the OLT asks for too many attributes, and the ONT can respond with however many attributes fit in its 25-byte attribute space. The OLT will get the appropriate attribute-present mask and will parse the attributes that were sent correctly. It will ask again later for those attributes that did not fit. + +While this is the preferred behaviour, an alternate interpretation may be that the ONT would return a "parameter error" code when it receives a get that does not fit in the get response. For the sake of interoperability, the expected behaviour between an OLT and ONT with different interpretations is provided below: + +- Case 1. The ONT reports a parameter error, and the OLT expects a partial list. If this happens, the OLT should react by simplifying its get request. The ONT will then respond without an error. +- Case 2. The ONT provides a partial list, while the OLT expects to get an error. The OLT will receive a normal message and will process it normally. The OLT should ask again for any attributes it did not get. + +### 11.1.10 Test result enumeration + +Test actions can return measurements of various physical parameters in vendor-specific ways. Table 11-4 identifies parameters that may be of interest, with enumerated values to represent them in the test response message defined in Appendix II. + +The resolution shown in the following descriptions merely indicates the weight attached to the least significant bit, and is not intended to impose requirements for precision or accuracy of the measured value. + +**Table 11-4 – Codes to represent measured values** + +| Type | Parameter | Representation | +|---------|--------------------------------------------------|------------------------------------------------------------------------------------------------------------------------| +| 1 | Power feed voltage, V | DC voltage, 2s complement, 20 mV resolution | +| 2 | Low voltage, V | DC voltage, 2s complement, 100 µV resolution | +| 3 | Received optical power, dB | dBµW, 2s complement, 0.002 dB resolution | +| 4 | Received optical power, W | Power, unsigned integer, 0.1 µW resolution | +| 5 | Transmitted optical power, dB | dBµW, 2s complement, 0.002 dB resolution | +| 6 | Transmitted optical power, W | Power, unsigned integer, 0.1 µW resolution | +| 7 | Video level, dB | dBmV, 2s complement, 0.002 dB resolution | +| 8 | Video level, V | RF voltage, unsigned integer, 200 µV resolution. May be filtered or weighted in accordance with vendor-specific needs. | +| 9 | Laser bias current | Unsigned integer, 2 µA resolution | +| 10 | Received signal quality measure Q | Unsigned integer, resolution 0.1 | +| 11 | Signal to noise ratio, dB | Unsigned integer, resolution 0.1 dB | +| 12 | Temperature, degrees C | 2s complement, 1/256 degree C resolution | +| 13..239 | Reserved for future standardization | | +| 240-254 | Not to be standardized, available for vendor use | | +| 255 | Reserved | Indicates an unavailable field in an ordered list of response values | + +## 11.2 Message flow control and error recovery + +The flow control/error recovery procedures for message exchange over the OMCC are based upon a simplex acknowledged transaction stop-and-wait mechanism that can easily be extended to support concurrent execution of multiple transaction requests of different priority levels. These flow-control procedures ensure that a low level acknowledged transaction request transmitted from the OLT has been properly received and processed to completion by the ONT before the next message of the same priority level is sent by the OLT. The stop-and-wait protocol uses the transaction correlation identifier field, retry counter(s), and applicable transaction request timer(s) to control the message flow rate while relying upon a CRC calculation to verify the data integrity of all received messages. + +A transaction request timer $T_i$ with expiration time $Tmax_i$ is started when a transaction request message of priority level "i" is sent to an ONT and is stopped upon receipt of an error-free acknowledgement message containing the same transaction correlation id value. If a valid acknowledgement message is not received by the OLT after timer $T_i$ expires, the OLT re-sends the original transaction request message. + +A retransmitted acknowledged transaction request message carries the same correlation ID as the original message. Each time an acknowledged transaction request message is retransmitted by the OLT, the transmitter increments the retry counter $R_i$ (the counter associated with priority level "i" acknowledged transaction requests). When a retry counter $R_i$ (initialized to 0x00 upon start-up) reaches the maximum retry value, $Rmax_i$ , the transmitter stops re-transmitting the message and declares an OMCC link state error. + +Note that these timers ( $T_i$ ) and retry counters ( $R_i$ ) are only maintained within the OLT controller and do not exist within the ONT. Furthermore, the default threshold values for timer expiration ( $Tmax_i$ ) and number of retries ( $Rmax_i$ ) are not subject to standardization. It is suggested that the default threshold values of both $Tmax$ and $Rmax$ be independently configurable for each priority level. The default value for $Tmax_1$ (i.e., high priority threshold) should account for the typical message transmission delay plus the command message response time. + +These flow control/error recovery procedures are illustrated in Figure 11.2-1 for a case where the OMCC link is not permanently broken. First, the OLT sends an acknowledged transaction request (message 1) with priority level 0. Subsequently (i.e., while message 1 is still outstanding), the OLT issues an additional acknowledged transaction request (message 2) with priority level 1. Both of these commands are received and executed with the associated response (acknowledgement messages) returned to the OLT by the ONT. The acknowledgement for message 1 is received by the OLT in time, however the response to message 2 is lost and never received. The OLT detects that something went wrong because timer $T_1$ expires, and the OLT therefore retransmits the original command (message 2). Note that the ONT detects that this retransmitted command is identical to the last received command (for priority level 1) and therefore does not re-execute it. The ONT simply retransmits the original response from the previous execution of message 2, which reaches the OLT in time. Finally, the OLT sends an acknowledged transaction request (message 3) with priority level 0, but the message itself gets lost and is never properly received by the ONT. After the associated timer ( $T_0$ ) expires, the OLT retransmits the command and now all goes well. + +![Sequence diagram showing concurrent message exchange with error recovery between OLT and ONT. The diagram illustrates three messages: Message 1 (Priority 0), Message 2 (Priority 1), and Message 3 (Priority 0). Message 1 is successfully acknowledged. Message 2 is acknowledged by the ONT but the response is lost; the OLT retransmits it, and the ONT recognizes it as a duplicate. Message 3 is lost; the OLT retransmits it, and the ONT receives it successfully.](5b7a8c9a545f503726bfee02ed5767c6_img.jpg) + +The diagram illustrates the following sequence of events: + +- OLT** starts timer $T_0$ and sends **Message 1/Priority 0/AR = 1/AK = 0/TID = 0x1234** to **ONT**. +- ONT** receives Message 1, starts **Execute message 1**, and sends **Ack message 1/Priority 0/AR = 0/AK = 1/TID = 0x1234** back to **OLT**. +- OLT** receives Ack message 1, stops timer $T_0$ , and starts timer $T_1$ . +- OLT** sends **Message 2/Priority 1/AR = 1/AK = 0/TID = 0x8123** to **ONT**. +- ONT** receives Message 2, starts **Execute message 2**, and sends **Ack message 2/Priority 1/AR = 0/AK = 1/TID = 0x8123** back to **OLT**. +- The Ack message 2 is lost (indicated by an 'X'). +- OLT** timer $T_1$ expires ( $T_1 > Tmax_1$ ). +- OLT** resends **Message 2/Priority 1/AR = 1/AK = 0/TID = 0x8123** to **ONT**. +- ONT** receives the retransmitted Message 2, recognizes it as a duplicate, and retransmits **Ack message 2/Priority 1/AR = 0/AK = 1/TID = 0x8123** to **OLT**. +- OLT** receives Ack message 2, restarts timer $T_1$ , increments retry counter $R_1$ , stops timer $T_1$ , and starts timer $T_0$ . +- OLT** sends **Message 3/Priority 0/AR = 1/AK = 0/TID = 0x1235** to **ONT**, but it is lost (indicated by an 'X'). +- OLT** timer $T_0$ expires ( $T_0 > Tmax_0$ ). +- OLT** resends **Message 3/Priority 0/AR = 1/AK = 0/TID = 0x1235** to **ONT**. +- ONT** receives Message 3, starts **Execute message 3**, and sends **Ack message 3/Priority 0/AR = 0/AK = 1/TID = 0x1235** back to **OLT**. +- OLT** receives Ack message 3, increments retry counter $R_0$ , stops timer $T_0$ , and starts timer $T_0$ again. + +Labels on the right side of the diagram indicate actions taken by the ONT: **Execute message 1**, **Execute message 2**, **Discard message 2 (no re-execution)**, and **Execute message 3**. + +G.984.4(08)\_F11.2-1 + +Sequence diagram showing concurrent message exchange with error recovery between OLT and ONT. The diagram illustrates three messages: Message 1 (Priority 0), Message 2 (Priority 1), and Message 3 (Priority 0). Message 1 is successfully acknowledged. Message 2 is acknowledged by the ONT but the response is lost; the OLT retransmits it, and the ONT recognizes it as a duplicate. Message 3 is lost; the OLT retransmits it, and the ONT receives it successfully. + +**Figure 11.2-1 – Concurrent Message Exchange with Error Recovery** + +A case where the OMCC link is effectively broken (down) is shown in Figure 11.2-2. + +![Sequence diagram illustrating OMCC link error detection between an OLT and an ONT. The OLT sends three identical messages (Message 4/Priority 0/AR = 1/AK = 0/TID = 0x1236) to the ONT. Each message is followed by an expiry timer (T0) that expires when T0 > Tmax0. Upon expiry, the OLT resends the message and restarts the timer. After the third resend, if the timer expires again (T0 > Tmax0) and the retry counter R0 exceeds Rmax0, the OLT declares a link error. The ONT does not respond to any of the messages, indicated by 'X' marks at the end of each message arrow.](d859e4d44aade987ebc31adfa6e4ea81_img.jpg) + +Sequence diagram illustrating OMCC link error detection between an OLT and an ONT. + +The OLT sends a message (Message 4/Priority 0/AR = 1/AK = 0/TID = 0x1236) to the ONT. The ONT does not respond (indicated by 'X'). + +The OLT starts a timer $T_0$ . Upon expiry $T_0$ ( $T_0 > T_{max0}$ ), the OLT resends Message 4, restarts $T_0$ , and increments $R_0$ . + +The OLT sends the message again. The ONT does not respond (indicated by 'X'). + +The OLT starts a timer $T_0$ . Upon expiry $T_0$ ( $T_0 > T_{max0}$ ), the OLT resends Message 4, restarts $T_0$ , and increments $R_0$ . + +The OLT sends the message again. The ONT does not respond (indicated by 'X'). + +The OLT starts a timer $T_0$ . Upon expiry $T_0$ ( $T_0 > T_{max0}$ ), the OLT increments $R_0$ . If $(R_0 > R_{max0})$ , the OLT declares a link error. + +G.984.4(08)\_F11.2-2 + +Sequence diagram illustrating OMCC link error detection between an OLT and an ONT. The OLT sends three identical messages (Message 4/Priority 0/AR = 1/AK = 0/TID = 0x1236) to the ONT. Each message is followed by an expiry timer (T0) that expires when T0 > Tmax0. Upon expiry, the OLT resends the message and restarts the timer. After the third resend, if the timer expires again (T0 > Tmax0) and the retry counter R0 exceeds Rmax0, the OLT declares a link error. The ONT does not respond to any of the messages, indicated by 'X' marks at the end of each message arrow. + +Figure 11.2-2 – OMCC link error detection + +## 11.3 OMCI handling within the ONT + +### 11.3.1 Prioritized protocol entities + +This clause specifies the behaviour of the ONT more precisely than in the preceding clause with respect to the prioritized request mechanism of the OMCC. + +Conceptually, the way the ONT handles the OMCC requests can be illustrated by referring to the dual priority level implementation example shown in Figure 11.3.1-1. + +When the ONT receives a GEM packet via the GEM port associated with the management channel, it shall calculate the CRC and compare it with the value found in the OMCI trailer. If the values do not match, the ONT shall discard the message. It is recommended that this event be logged by the ONT and possibly communicated to the OLT by some out-of-band mechanism but, as far as the protocol is concerned, the message is discarded silently. + +Messages with a correct CRC are then placed into either of two distinct incoming FIFO-based message queues, according to the priority level (i.e., high or low) of the associated command. Note that the priority level of a given command is encoded using the most significant bit of the transaction correlation identifier field. If the associated incoming message queue is already full, the ONT must simply discard the message. It is recommended that this event be logged by the ONT and possibly communicated to the OLT by some out-of-band mechanism but, as far as the protocol is concerned, the message is discarded silently. + +There are two distinct incoming command processing protocol entities (one associated with each priority level) that are used to service messages sequentially from an independently associated incoming FIFO queue. Each of these protocol entities can execute concurrently. If a message is a + +one-way command (i.e., an unacknowledged command), the protocol entity will simply have the command executed. If a message is an acknowledged command, the protocol entity must first look at the transaction correlation identifier. If it is not equal to the transaction correlation identifier of the last executed command with the same priority level, the protocol entity will have the command executed and place the response/acknowledgement (with identical transaction correlation identifier) in the outgoing FIFO queue of the same priority level. If the transaction correlation identifier is equal to that of the last executed command with the same priority level (i.e., the case where the controller retransmits a command due to lack of proper acknowledgement), the protocol entity will not actually have the command executed but simply will place the response from the last execution of that command in the outgoing FIFO queue (i.e., re-send the previous acknowledgement response). It is assumed that in both cases the command processing protocol entity for a given priority level will block until there is room in the associated outgoing FIFO queue for the response message. + +In the other direction, requests by the applications to send autonomous event notifications will simply result in the corresponding messages being directed to an event notification protocol entity for transmission to the OLT. The event notification protocol entity will forward these event notification messages to the low priority outgoing FIFO queue. In this case as well, the event notification protocol entity will block until there is room in the low priority outgoing FIFO queue to hold the notification message. The CRC generator will remove messages from the outgoing FIFO queues using a strict priority discipline (i.e., the low-priority queue will only be served when the high-priority queue is empty), generate a CRC, append a properly-formatted OMCI trailer to the packet payload, and transmit the message to the OLT. + +![Figure 11.3.1-1 – Protocol entities within the ONT](0213ecab177e330d21a6ea61a2ee0344_img.jpg) + +``` + + graph LR + subgraph CRC_Modules + CRC_gen[CRC generation] + CRC_val[CRC validation] + end + + subgraph FIFO_Queues + HP_FIFO_Out[High priority FIFO queue] + LP_FIFO_Out[Low priority FIFO queue] + HP_FIFO_In[High priority FIFO queue] + LP_FIFO_In[Low priority FIFO queue] + end + + subgraph Protocol_Entities + Event_Prot[Event notification protocol entity] + HP_Prot[High priority protocol entity] + LP_Prot[Low priority protocol entity] + end + + Apps[Applications] + + %% Connections + CRC_gen --> HP_FIFO_Out + CRC_gen --> LP_FIFO_Out + HP_FIFO_Out --> HP_Prot + LP_FIFO_Out --> Event_Prot + LP_FIFO_Out --> LP_Prot + + CRC_val --> HP_FIFO_In + CRC_val --> LP_FIFO_In + HP_FIFO_In --> HP_Prot + LP_FIFO_In --> LP_Prot + + HP_Prot <--> Apps + LP_Prot <--> Apps + Event_Prot <-- Apps + + %% Discards + CRC_val --> CRC_Err[CRC error discard] + LP_FIFO_In --> FIFO_Over[FIFO overflow discard] + +``` + +Detailed description: The diagram shows the data flow between the OLT (via CRC modules) and internal ONT Applications. On the transmit side (top), the CRC generation module pulls from High and Low priority FIFO queues. The High priority queue is fed by the High priority protocol entity, while the Low priority queue is fed by both the Event notification and Low priority protocol entities. On the receive side (bottom), the CRC validation module feeds High and Low priority FIFO queues, which in turn feed their respective protocol entities. The protocol entities interact bidirectionally with the Applications block. Discard paths are shown for CRC errors and FIFO overflows. + +Figure 11.3.1-1 – Protocol entities within the ONT + +**Figure 11.3.1-1 – Protocol entities within the ONT** + +**11.3.2 Restrictions on the actions in relation to the protocol entities** + +To reduce the complexity and the amount of memory necessary in the ONT, the OLT is not allowed to issue a MIB upload or a software download of a certain priority level while a similar action in the other priority level is in progress. + +**11.3.3 Usage of the default alloc-id** + +The OMCC is carried in the upstream in the default allocation ID. In some implementations, the default alloc-id is also used for user traffic, and is associated with a T-CONT ME. In these cases, the OMCC traffic is combined with the T-CONT traffic using a simple strict-priority multiplexing, with the OMCC having higher priority. + +Rec. ITU-T G.984.4 (02/2008) 343 + +# Appendix I + +## OMCI common mechanisms and services + +(This appendix does not form an integral part of this Recommendation) + +This appendix describes the common mechanisms of the OMCI, e.g., the MIB resynchronization, and the OMCI services, e.g., the equipment management or connection management. + +## I.1 Common mechanisms + +The common mechanisms consist of: + +- a) MIB data sync increase. +- b) MIB audit and resynchronization. +- c) Alarm sequence number increase. +- d) Alarm audit and resynchronization. +- e) Get an attribute that is larger than the OMCI message contents field. +- f) Create an instance of a managed entity with an attribute that is larger than the OMCI message contents field. +- g) Reporting of test result. +- h) Alarm reporting control. + +These common mechanisms are explained by the use of scenario diagrams. + +### I.1.1 MIB data sync increase + +The MIB at the OLT and the instances of the managed entities in the ONT have to be synchronized at all times. This clause describes the means for achieving this. The "tool" used for this is the MIB data sync attribute of the ONT data managed entity. + +The MIB data sync attribute is a global eight-bit *sequence number*. When auditing the MIB in the ONT, the OLT requests this sequence number. If this number coincides with the corresponding sequence number in the OLT, no further action is needed, as the two MIBs, in ONT and OLT, are thought to be identical. If there is a discrepancy, the OLT either 1) downloads its copy (including the MIB data sync) of the MIB to the ONT, or 2) uploads the MIB of the ONT, compares it with its own MIB, sends the necessary commands to the ONT to correct the differences and downloads its sequence number. + +The ONT will be audited with respect to its MIB in three cases: + +- a) On loss and re-establishment of the OMCC. +- b) Periodically, based on the operator's requirements. +- c) On demand of the OpS. + +On detecting a newly installed ONT, regardless of the sequence number of its MIB, the OLT will perform either a MIB audit followed by whatever modifications are required, or a MIB reset and ONT startup procedure (see clause I.2.1). + +The MIB data sync counter will be incremented for the creation and deletion of managed entity instances that are the consequence of a command by the OLT. The MIB data sync counter will also be incremented for attribute value changes which are the consequence of a command by the OLT. The MIB data sync counter will be incremented once per executed command (see Figures I.1.1-1 and I.1.1-2). + +In contrast, the MIB data sync counter will not be incremented for autonomous creation and deletion of managed entity instances by the ONT itself. Neither will the MIB data sync counter be incremented for autonomous changes to attributes of managed entities within the ONT (see Figures I.1.1-3 and I.1.1-4). + +The order in which the OLT and the ONT will update their MIBs and increment the MIB data sync is not imposed. However, both the OLT and the ONT must locally update the MIB and increment the MIB data sync as one atomic action. + +When incremented, the sequence number that follows 255 is 1. 0x00 is reserved for the following cases: + +- a) Default MIB with which the ONT left the factory. +- b) An ONT which after (re-)initialization cannot restore its MIB. + +In other words, a sequence number of 0 indicates that the ONT's MIB is not well defined, and therefore requires audit/reconfiguration. + +Note that no mechanisms exist to detect that an autonomous attribute value change notification has been lost. Therefore, the OLT must regularly read the values of the attributes that can change their values autonomously. + +![Sequence diagram showing the increment of MIB data sync at ONT and OLT under OLT command.](fe7ce38208f739f617c272d8238c7bfa_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: ONU Executes command +ONU updates the MIB and +MIB data sync. + OLT->>ONU: Command[ANY_ME](inst) + Note left of OLT: OLT Updates Its MIB and +increments its MIB data sync. + ONU-->>OLT: Response[ANY_ME](inst, result = success) + Note bottom: The MIB in the OLT and ONU +Are now aligned. +``` + +The diagram illustrates a sequence of interactions between an OLT and an ONU. It begins with the OLT sending a 'Command[ANY\_ME](inst)' message to the ONU. Upon receiving the command, the ONU executes it, updates its MIB, and increments its MIB data sync. The ONU then sends a 'Response[ANY\_ME](inst, result = success)' back to the OLT. Upon receiving the response, the OLT updates its MIB and increments its MIB data sync. Finally, a note at the bottom indicates that the MIBs in both the OLT and ONU are now aligned. + +Sequence diagram showing the increment of MIB data sync at ONT and OLT under OLT command. + +Figure I.1.1-1 – Increment of MIB data sync at ONT and OLT under OLT command + +![Sequence diagram showing OLT and ONU interaction for MIB data sync increment via OLT command.](ba727916d67bd9a343429b763a6e8f12_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: OLT Updates Its MIB and increments its MIB data sync. + OLT->>ONU: Command[ANY_ME](inst) + Note right of ONU: ONU cannot execute the command. + ONU-->>OLT: Response[ANY_ME](inst, result = error code) + Note left of OLT: The MIB in the OLT and ONU Are not aligned. They will become aligned only after a MIB resynchronization process. + +``` + +The diagram illustrates a sequence of events between an OLT and an ONU. It begins with a note on the OLT side stating "OLT Updates Its MIB and increments its MIB data sync." A message "Command[ANY\_ME](inst)" is sent from the OLT to the ONU. The ONU responds with a note "ONU cannot execute the command." and a message "Response[ANY\_ME](inst, result = error code)" back to the OLT. A final note on the OLT side indicates that the MIBs are not aligned and will only be aligned after a resynchronization process. + +Sequence diagram showing OLT and ONU interaction for MIB data sync increment via OLT command. + +**Figure I.1.1-2 – Increment of MIB data sync at ONT and OLT under OLT command** + +![Sequence diagram showing OLT and ONU interaction for autonomous attribute value change.](9d354ffb3f05c847e46b22f0c3b7ebff_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: An attribute value has changed autonomously. The ONU updates the MIB + ONU-->>OLT: Attribute Value Change Notification[ANY_ME](inst, attr mask, attr) + Note left of OLT: Notification reaches the OLT. The OLT updates its MIB The MIB in the OLT and ONU are aligned + +``` + +The diagram shows an autonomous attribute value change on the ONU side, with a note stating "An attribute value has changed autonomously. The ONU updates the MIB". A message "Attribute Value Change Notification[ANY\_ME](inst, attr mask, attr)" is sent from the ONU to the OLT. The OLT receives the notification with a note "Notification reaches the OLT. The OLT updates its MIB The MIB in the OLT and ONU are aligned", indicating that the MIBs are now aligned without a separate resynchronization process. + +Sequence diagram showing OLT and ONU interaction for autonomous attribute value change. + +**Figure I.1.1-3 – No increment of MIB data sync at ONT and OLT in case of autonomous attribute value changes** + +![Sequence diagram showing a notification failure between an OLT and an ONU. The ONU updates its MIB autonomously, but the notification does not reach the OLT, causing a misalignment.](601a4295d83c115fcd66101f49de0c4e_img.jpg) + +This sequence diagram illustrates a scenario where an autonomous change on the ONU does not result in a successful notification to the OLT. The OLT's side shows a box stating: "Notification does not reach the OLT. The MIB in the OLT and ONU are not aligned. They will become aligned again only after a MIB resynchronization process." The ONU's side shows a box stating: "An attribute value has changed autonomously. The ONU updates the MIB". + +Sequence diagram showing a notification failure between an OLT and an ONU. The ONU updates its MIB autonomously, but the notification does not reach the OLT, causing a misalignment. + +**Figure I.1.1-4 – No increment of MIB data sync at ONT and OLT in case of autonomous attribute value changes** + +#### I.1.2 MIB audit and resynchronization + +Figures I.1.2-1 and I.1.2-2 show the scenario diagram of the MIB audit and MIB resynchronization process. + +![Sequence diagram showing the MIB audit and resynchronization process initiated by the OLT.](4141e32339a99ae82b6360896250e1fc_img.jpg) + +This sequence diagram shows the MIB audit and resynchronization process. It begins with a box on the OLT side: "The OLT requests the MIB data sync." A message arrow labeled "Get\_cmd[ONT\_Data](inst = 0, attr mask = MIB Data sync)" points from the OLT to the ONU. A return message arrow labeled "Get\_rsp[ONT\_Data](inst = 0, attr mask = MIB data sync, attr data)" points from the ONU back to the OLT. The process concludes with a box on the OLT side: "OLT compares the retrieved MIB data sync value with its own copy. The MIB data syncs match: the OLT can safely assume that the MIB are aligned." + +Sequence diagram showing the MIB audit and resynchronization process initiated by the OLT. + +**Figure I.1.2-1 – Audit and MIB resynchronization** + +![Sequence diagram showing OLT and ONU interaction for MIB resynchronization. The process involves a MIB data sync request, a comparison by the OLT, a MIB upload command, and subsequent MIBUploadNext requests for each instance.](f255509950abf586126ef0940d594f9c_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + + Note left of OLT: The OLT requests the MIB data sync. + OLT->>ONU: Get_cmd[ONT_Data](inst = 0, attr mask = MIB Data sync) + ONU-->>OLT: Get_rsp[ONT_Data](inst = 0, success, attr mask, attr data) + Note left of OLT: OLT compares the retrieved MIB data sync value with its own copy. The MIB data syncs do not match: the OLT can align the MIBs incrementally. For this, the OLT first uploads the MIB of the ONT + OLT->>ONU: MIBUpload_cmd[ONT_Data](inst = 0) + Note right of ONU: The ONU makes a copy of the MIB, thus the ONU will have an active MIB(A_ONU) and a copy (C_ONU). The ONU responds to the request with the indication of the number of instances (N+1) to upload. + ONU-->>OLT: MIBUpload_rsp[ONT_Data](inst = 0, number of commands(N)) + Note left of OLT: The OLT requests the information of all instances in the MIB of the ONU. The ONU can still send AVCs and the OLT can still send configuration requests during the upload. + OLT->>ONU: MIBUploadNext_cmd[ONT_Data](inst = 0, command sequence=0) + ONU-->>OLT: MIBUploadNext_rsp[ONT_Data](ME class, inst, attr mask, attr data) + Note right of ONU: ... + OLT->>ONU: MIBUploadNext_cmd[ONT_Data](inst = 0, command sequence=N) + ONU-->>OLT: MIBUploadNext_rsp[ONT_Data](ME class, inst, attr mask, attr data) + +``` + +Sequence diagram showing OLT and ONU interaction for MIB resynchronization. The process involves a MIB data sync request, a comparison by the OLT, a MIB upload command, and subsequent MIBUploadNext requests for each instance. + +**Figure I.1.2-2 – Audit and MIB resynchronization** + +The OLT must issue as many MIBUploadNext requests as the number of instances given in the MIBUpload response. The maximum time between two MIBUploadNext requests is 1 minute. If the OLT does not send a MIBUploadNext request within this time after the previous MIBUploadNext request or after the MIBUpload start request, the ONT assumes the MIB upload to be terminated. The ONT can drop the copy of the MIB, and consider any MIBUploadNext requests to be out of range, as described in clause II.2.22. + +It should be noted that certain MEs and attributes are not to be included in the MIB audit. This is for reasons of efficiency and protocol simplification. In particular, instances of all performance management MEs and the managed entity ME and the Attribute ME should not be included in the MIB audit. All table attributes should not be included in the MIB audit, even though their parent ME is included. If the OLT requires this information, it will obtain it by directly reading it. + +### I.1.3 Alarm sequence number increase + +The ONT informs the OLT of alarm status changes by sending alarm status change notifications. Note that these notifications are sent in unacknowledged messages that carry an eight-bit alarm sequence number for the benefit of the OLT to detect loss of alarm notifications (Figures I.1.3-1 and I.1.3-2). After a restart of the ONT, the alarm sequence number is reset so that the first alarm notification sent by the ONT will have an alarm sequence number equal to 1. The alarm message sequence number is incremented for each alarm notification and wraps around from 255 to 1. Consequently, an alarm notification with sequence number 0x00 will never be sent. + +![Sequence diagram showing the increment of alarm sequence number at ONT and OLT. The diagram involves two lifelines: OLT and ONU. The process starts at the ONU where a fault occurs, the alarm table is updated, and the alarm sequence number is incremented. The ONU then sends a notification message 'Alarm[ANY_ME](inst, alarm mask)' to the OLT. Upon receiving the message, the OLT updates its alarm table and sequence number, aligning it with the ONU's.](47be7141001b1cc76e05845525fc9e50_img.jpg) + +``` +sequenceDiagram + participant ONU + participant OLT + Note right of ONU: A fault has occurred. The ONU updates its alarm table and increments the alarm sequence number. +The ONU sends a notification to the OLT. + ONU->>OLT: Alarm[ANY_ME](inst, alarm mask) + Note left of OLT: The OLT updates its alarm table and alarm sequence number. +The alarm tables in the OLT and ONU are aligned. +``` + +Sequence diagram showing the increment of alarm sequence number at ONT and OLT. The diagram involves two lifelines: OLT and ONU. The process starts at the ONU where a fault occurs, the alarm table is updated, and the alarm sequence number is incremented. The ONU then sends a notification message 'Alarm[ANY\_ME](inst, alarm mask)' to the OLT. Upon receiving the message, the OLT updates its alarm table and sequence number, aligning it with the ONU's. + +Figure I.1.3-1 – Increment of alarm sequence number at ONT and OLT + +![Sequence diagram showing OLT and ONU interaction regarding alarm sequence numbers. The OLT has a note about misaligned alarm tables. The ONU has a note about a fault occurrence and inability to notify the OLT.](d0afd1f27493bfe694ce00930db0f3a5_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of OLT: The alarm tables in the OLT and ONU are not aligned. They will become aligned only after an alarm resynchronization process. + Note right of ONU: A fault has occurred. The ONU updates its alarm table and increments the alarm sequence number. The ONU is unable to send a notification to the OLT. + +``` + +Sequence diagram showing OLT and ONU interaction regarding alarm sequence numbers. The OLT has a note about misaligned alarm tables. The ONU has a note about a fault occurrence and inability to notify the OLT. + +**Figure I.1.3-2 – Increment of alarm sequence number at ONT and OLT** + +#### I.1.4 Alarm audit and resynchronization + +When the OLT detects a gap in the received sequence, as shown in Figure I.1.4-1, it asks the ONT for an alarm status report by sending a "get all active alarms" command targeted at the "ONT data" ME. Obviously, this command is acknowledged by a response that contains the number of managed entity instances that have outstanding alarms. The OLT will request the alarm status of all these managed entities instances via the "get all alarms next" command targeted at the ONT data ME. The OLT will compare these alarm statuses of all these instances with its own and will notify the network manager of the changes. The alarm sequence number is reset by the ONT when it receives the "get all active alarms" request. + +![Sequence diagram showing OLT and ONU interaction for audit and alarm resynchronization. The OLT detects a missing alarm notification and sends a GetAllAlarms_cmd to the ONU. The ONU copies the current alarm status table and resets the alarm sequence number. The ONU responds with a GetAllAlarms_rsp indicating the number of commands (N). The OLT creates a blank alarm status table and requests the alarm status using the number of commands indicated. The OLT then sends GetAllAlarmsNext_cmd requests for each instance (0 to N). The ONU responds with alarm information for each instance. During this process, the ONU can still send alarm notifications, which the OLT places in its active alarm table. Finally, the OLT copies the populated sequence into its alarm table.](29e446c8e2363d27e282737c3d7c3421_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT detects a missing alarm notification. + OLT->>ONU: GetAllAlarms_cmd[ONT_Data](inst=0) + Note right of ONU: The ONU makes a copy of the current alarm status table of all managed entity instances, thus the ONU will have an active (A_ONU) and a copy (C_ONU) of the alarm table. + Note right of ONU: The ONU resets the alarm sequence number and responds to the request with an indication of the number of instances (N+1) which are required to retrieve the active alarms. + ONU->>OLT: GetAllAlarms_rsp[ONT_Data](inst=0,number of commands (N)) + Note left of OLT: The OLT makes a blank alarm status table, thus the OLT will have an active alarm table (A_OLT) and a blank version (C_OLT). The OLT requests the alarm status using the number of commands indicated in the response. + OLT->>ONU: GetAllAlarmsNext_cmd[ONT_Data](inst=0, cmd seq num = 0.) + Note right of OLT: During the Alarm Resynchronization, the ONU can still send alarm notifications. The OLT places the contents of these notifications in the active alarm table (A_OLT). + ONU->>OLT: GetAllAlarmsNext_rsp[ONT_Data](inst=0,ME class,inst, alarms) + Note right of ONU: ... + Note left of OLT: ... + OLT->>ONU: GetAllAlarmsNext_cmd[ONT_Data](inst=0, cmd seq num = N.) + ONU->>OLT: GetAllAlarmsNext_rsp[ONT_Data](inst=0, ME class,inst, alarms) + Note left of OLT: The OLT copies the (C_OLT) populated from the GetAllAlarm sequence, skipping the new alarms in the (A_OLT) alarm table. + +``` + +Sequence diagram showing OLT and ONU interaction for audit and alarm resynchronization. The OLT detects a missing alarm notification and sends a GetAllAlarms\_cmd to the ONU. The ONU copies the current alarm status table and resets the alarm sequence number. The ONU responds with a GetAllAlarms\_rsp indicating the number of commands (N). The OLT creates a blank alarm status table and requests the alarm status using the number of commands indicated. The OLT then sends GetAllAlarmsNext\_cmd requests for each instance (0 to N). The ONU responds with alarm information for each instance. During this process, the ONU can still send alarm notifications, which the OLT places in its active alarm table. Finally, the OLT copies the populated sequence into its alarm table. + +**Figure I.1.4-1 – Audit and alarm resynchronization** + +The OLT must issue as many GetAllAlarmsNext requests as the number of instances given in the GetAllAlarms start response. The maximum time between two GetAllAlarmsNext requests is one minute. If the OLT does not send a GetAllAlarmsNext request within this time after the previous GetAllAlarmsNext request or after the GetAllAlarms start request, the ONT assumes the alarm upload to be terminated. The ONT can drop the copy of the alarm table, and consider any GetAllAlarmsNext requests to be out of range, as described in clause II.2.18. + +### 1.1.5 Table attributes + +Normal attributes are coded such that they do not exceed the maximum OMCI attribute size. However, there are cases where attributes need to be larger because they comprise arrays of data. In other cases, the attribute may be unstructured, but nevertheless be too large to be represented as a conventional attribute. Both types of large attributes are known as tables, and can be identified by the word "table" in their name. + +For all such attributes, the 'set' action is used to set a single entry in the table, the size of which is specified in clause 9 for the particular attribute in question. This is possible only when individual table entries do not exceed the maximum size that can be conveyed in the set operation. Otherwise, the table attribute is restricted to being read-only. + +The actual size of any given table attribute instance at any given time may be smaller than the OMCI single-message limit. Regardless of their actual size, however, the following treatment shall be used to control the retrieval of all table attributes. + +Figure I.1.5-1 shows the scenario diagram when the OLT gets a table attribute that is larger than the OMCI message contents field (see clause 11.1.9 for limitations). The OLT asks the ONT for the size of the attribute by sending a get command. In the get response, the ONT uses four bytes to indicate the size of the data. This implies that the get response message is formatted as if the oversized attribute had a size of four bytes. Then, the OLT will request the attribute data from the ONT via the appropriate number of get next commands. + +![Sequence diagram showing the interaction between OLT and ONU to retrieve a large table attribute. The OLT sends a Get_cmd to the ONU, which responds with a Get_rsp containing the data size. The OLT then sends multiple GetNext_cmd messages to retrieve the data in chunks, with the ONU responding with GetNext_rsp messages. Callouts indicate that during the GetNext sequence, the ONU can still send AVCs and the OLT can still send configuration commands.](2ea65c467f59812b888d61ca29becebc_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT requests the size of the attribute + OLT->>ONU: Get_cmd[ANY_ME](inst, attribute mask) + Note right of ONU: The ONU makes a copy of the attribute. The ONU responds to the request with the size of the attribute + ONU-->>OLT: Get_rsp[ANY_ME](inst, attr mask, DataSize = 29*N+m bytes) + Note left of OLT: The OLT requests the attribute data by sending the appropriate number of GetNext commands + OLT->>ONU: GetNext_cmd[ANY_ME](inst, attr mask, SeqNumber = 0) + ONU-->>OLT: GetNext_rsp[ANY_ME](inst, attr mask, 1st 29 bytes of attr data) + Note right of ONU: During the GetNext sequence, the ONU can still send AVCs. When received by the OLT, updates its active MIB and marks the attribute as changed. + Note left of OLT: During the GetNext sequence, the OLT can still send configuration commands. When received by the ONU, it updates its active MIB and sends a response to the OLT. + OLT->>ONU: GetNext_cmd[ANY_ME](inst, attr mask, SeqNumber = N) + ONU-->>OLT: GetNext_rsp[ANY_ME](inst, attr mask, last m bytes of attr data) +``` + +Sequence diagram showing the interaction between OLT and ONU to retrieve a large table attribute. The OLT sends a Get\_cmd to the ONU, which responds with a Get\_rsp containing the data size. The OLT then sends multiple GetNext\_cmd messages to retrieve the data in chunks, with the ONU responding with GetNext\_rsp messages. Callouts indicate that during the GetNext sequence, the ONU can still send AVCs and the OLT can still send configuration commands. + +G.984.4(08)\_FI.1.5-1 + +**Figure I.1.5-1 – Get an attribute that is larger than the OMCI message field** + +The OLT must issue as many "get next" requests as needed to accommodate the size of the data indicated in the get response. The maximum time between two "get next" requests is 60 seconds. If the OLT does not send a "get next" request within this time after the previous "get next" request or after the get start request, the ONT assumes the get attribute command has been terminated and can drop the copy of the attribute, and consider any get next requests to be out of range, as described in clause II.2.44. In addition, the OLT should not initiate simultaneous multiple get next processes to any one ONT, because capturing multiple snapshots of potentially large tables could exhaust the limited memory resources of the ONT. Only if there is a special purpose for simultaneous get next sequences should such an action be attempted. + +#### I.1.6 This clause intentionally left blank + +(No subordinate text) + +### I.1.7 Report test result + +Figure I.1.7-1 shows the scenario diagram for when the OLT requests that the ONT perform a test. The OLT requests that the ONT start testing by sending a "test" command. This command is acknowledged by a "test" response. Then, the ONT carries out the test. After the test is complete, the ONT reports the test result via a "test result" notification message. This scenario is used for the "self test" attribute of ONT-G managed entity or circuit pack managed entity. Moreover, this scenario may be useful for MLT tests or for additional tests that may be added in the future. + +![Sequence diagram showing the interaction between an OLT and an ONU for reporting test results. The OLT sends a 'Test command' to the ONU, which responds with a 'Test response'. The ONU then performs the test and sends a 'Test result notification' back to the OLT. A note indicates that the ONU can still send AVCs during the test operation.](a8e2aac7919c9dda82a304bfacc58dc8_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT requests a test + OLT->>ONU: Test command (ME type, instance, test selection) + ONU-->>OLT: Test response (ME type, instance, success) + Note right of ONU: The ONU can still send AVCs during the test operation + Note right of ONU: The ONU carries out the requested tests and reports the results to the OLT + ONU-->>OLT: Test result notification (ME type, instance, pass/fail, details) + +``` + +G.984.4(08)\_FI.1.7-1 + +Sequence diagram showing the interaction between an OLT and an ONU for reporting test results. The OLT sends a 'Test command' to the ONU, which responds with a 'Test response'. The ONU then performs the test and sends a 'Test result notification' back to the OLT. A note indicates that the ONU can still send AVCs during the test operation. + +**Figure I.1.7-1 – Reporting of test result** + +The ONT may also report a test result autonomously in cases where it performs routine background tests. An autonomous test report may be identified by the fact that its transactions identifier is 0. An autonomous test report normally occurs only when some measured value is out of tolerance, and may therefore be reported in conjunction with an alarm. + +### I.1.8 Alarm reporting control + +Alarm reporting control allows for the suppression of alarms from physical path termination points, under the control of the management system. A complete description of ARC from a generic viewpoint is given in [ITU-T M.3100]. The OMCI provides for ARC functions using two attributes of the PTP: ARC and ARC interval. These two attributes are described below. + +##### ARC + +This attribute allows the activation of alarm reporting control (ARC) for this PPTP. The attribute works in concert with the ARC\_interval attribute. A value of zero indicates disabled, while a value of 1 indicates enabled. The default value is disabled. When the ARC attribute is set to disabled, the PPTP is in the "ALM" state, as defined in [ITU-T M.3100]. Alarms are reported normally in the ALM state. When the ARC attribute is set to enabled, the PPTP is in the "NALM-QI" state, as defined in [ITU-T M.3100]. Alarms are suppressed in this state. + +The PPTP moves from the ALM state to the NALM-QI state when the OLT changes the ARC attribute to enabled. The PPTP moves from the NALM-QI state to the ALM state when either 1) the PPTP is trouble-free and the ARC\_interval timer expires, or 2) the ARC attribute is set to disabled by the OLT. If the ARC\_interval timer expires, the ONT sets the ARC attribute to disabled autonomously, and sends an AVC to notify the OLT. Please refer to [ITU-T M.3100] for more extensive discussion. + +Note that the ARC\_interval can assume normal timing values of 0 to 254 minutes. The value 0 implies that a PPTP in the NALM-QI state goes immediately to the ALM state upon detection of a problem-free state. An ARC\_interval value of 255 has the special meaning that the timer never expires. The PPTP remains in the NALM-QI state until the OLT sets the ARC attribute to disabled. This behaviour is equivalent to the "NALM" state, which is another generic behaviour of the ARC function in [ITU-T M.3100]. + +Note that there is no support for the NALM-TI sub-function in the OMCI system. (R,W) (optional) (1 byte) + +#### ARC\_interval + +This attribute defines the interval to be used with the ARC function for this PPTP. The values 0 through 254 give the duration in minutes for the NALM-QI timer. The special value 255 means that the timer never expires. The default value is zero. (R, W) (optional) (1 byte) + +Note that ARC suppresses the reporting of the alarms, and not the alarm conditions themselves. Therefore, if an alarm condition develops during an ARC interval, then the ONT should maintain the internal indication of the alarm, and if the OLT gets all the alarms, it should be reported. + +### I.1.9 Performance monitoring + +This Recommendation defines a number of performance monitoring managed entities. They share a number of characteristics, as described here. Possible exceptions to the generic behaviour are defined in the specific managed entity affected. + +PM managed entities are created and deleted by the OLT, and the managed entity ID attribute takes the same value as the parent managed entity's ME ID, so that no explicit pointer is required. + +Each PM managed entity contains a pointer to an instance of the threshold data 1/2 managed entities, which allow for thresholding and threshold crossing alerts (TCAs). Not all PM attributes need to be thresholded; thresholding is part of the definition of each PM managed entity. Even when thresholding is defined on a managed entity, it is the option of the OLT whether to provision it (see clause I.1.10 regarding optional pointers). If fewer than seven thresholded counters appear in an ME's definition, the threshold data 2 ME is not needed. + +The ONT performs no archival; archival is the function of the OLT or a management system. Conceptually, the ONT has only two storage bins: a current accumulator and a history bin. At 15-minute intervals, they switch roles. History is discarded at age thirty minutes, when the previous history bin is initialized into its role as the new current accumulator. The previous accumulator, now in its role as the history bin, retains its totals for 15 minutes, so that the OLT can upload them if desired. + +The sequence of 15-minute intervals is initiated by the synchronize time action, issued by the OLT against the ONT-G managed entity. This establishes a 15-minute tick boundary and starts numbering the intervals from 0. The interval number is returned in the interval end time attribute, which is a standard attribute of all PM managed entities. + +The interval count is a single byte, which rolls over from 255 back to 0. + +The synchronize time action is the only mechanism guaranteed to reset either the phase or the interval number. For example, neither ONT re-boot nor MIB reset can be expected to have these effects (the performance monitoring consequence of the latter events is undefined). + +During the accumulation interval, the PM managed entity collects performance statistics in accordance with its definition, and continuously compares the accumulated values with thresholds that may exist. When an accumulated value becomes equal to the threshold, the ONT originates a threshold crossing alert (TCA). At the end of the current 15-minute interval, the ONT issues a second TCA, cancelling the first. + +It should be noted that TCAs are reported in OMCI alarm messages. The MEs are arranged so that there is no overlap between TCA codepoints and alarm codepoints, mainly due to the fact that MEs typically declare either alarms or TCAs, but not both. + +The get action on a PM managed entity returns the values of attributes in the history bin. An ONT may also support an optional action, get current data. The effect of this action is to return the value of attributes in the current accumulator. + +Most PM attributes are counters. If a counter should fill up during the interval, it remains at its maximum possible value, rather than rolling over. In a few special cases, such as traffic loss ratio, the attribute acquires a value only at the close of a 15-minute interval. The value returned by a get current data operation is undefined. If a threshold is defined on such an attribute, the TCA is declared at the end of the 15-minute interval and then immediately cleared as the registers are re-initialized. + +### **I.1.10 Optional pointers** + +In many cases, populating a pointer attribute may be optional (the prime example being the threshold data 1/2 id attribute). When this happens, it is useful to be able to specify a null pointer in OMCI. Because the OLT defines the pointers and the MEs to which they point, if the OLT has the intention to not populate the optional pointer, it can do so by filling in any value that does not correspond to an ME that exists. The ONT can therefore determine that the pointer 'points to nothing,' and is therefore null. By convention, however, both 0 and 0xFFFF are often reserved as attribute values to designate a null pointer. OLT conventions may vary for historical reasons; the ONT should recognize either value. + +## **I.2 Common services** + +The common services consist of: + +- a) start-up phase of ONT; +- b) on demand circuit pack provisioning; +- c) on demand circuit pack de-provisioning; +- d) plug-and-play circuit pack provisioning; +- e) plug-and-play circuit pack de-provisioning; +- f) software image download; +- g) software image changes. + +All the listed services are explained by the use of scenario diagrams. + +### **I.2.1 Start-up phase of ONT** + +The start-up phase of an ONT, from the OMCI point of view, belongs to one of two cases: + +- a) the ONT is "new" to the OLT; or +- b) the OLT already "saw" this ONT at this PON. + +The details of start-up scenarios also vary for ONTs with different configuration options, e.g.: + +- a) ONT with cardholders at both PON IF and UNI; +- b) ONT with integrated interfaces at both PON IF and UNI; +- c) ONT with cardholders at PON IF and integrated interfaces at UNI; and +- d) ONT with integrated interfaces at PON IF and cardholders at UNI. + +Here the following scenarios will only show cases a) and b), from which the scenarios for cases c) and d) can be deduced. Additional scenarios can be derived for the cases where an ONT contains common equipment and/or protected equipment. + +NOTE – The preferred solution is that cardholder and circuit managed entities should always be modelled, regardless of whether or not the ONT has integrated interfaces. However, the port mapping package provides another way to map heterogeneous ports to a single parent equipment. + +Figure I.2.1-1 shows the start-up phase of a "new" ONT with Cardholders on both sides. Figure I.2.1-2 shows the start-up phase of a "new" ONT with integrated interfaces on both sides. Figure I.2.1-3 shows the start-up phase of an "old" ONT. + +The behaviour of the ONT with respect to inserted circuit packs during the start-up phase is not shown in the following figures. This behaviour is the subject of clause I.2.2. + +Note that if attribute value changes do not arrive at the OLT, the OLT will not know the number of cardholders or integrated ports that reside in the ONT. The OLT can request the information of the newly created managed entity instances by a sequence of "get" requests. If a "get" request is issued on a non-existing instance, the response message to the OLT will indicate the error – Unknown managed entity instance. + +In general, the AVCs shown in Figures I.2.1-1 and I.2.1-2 should be viewed as a partial method of ONT discovery. The OLT cannot rely on the receipt of AVCs to learn all ONT information, because not all managed entities or attributes issue AVCs, and because AVCs can be lost in transmission without an error being detected. Therefore, the OLT should audit any ONT immediately after a reset is completed. + +![Sequence diagram showing the start-up of a 'new' ONT with cardholders on both sides. The diagram involves two main entities: OLT and ONU. The process starts with the OLT accepting the ONU as 'new' and clearing its MIB. The ONU checks for a MIB; if not present, it creates the ONT-G, ONT Data, and OLT managed entities. The OLT sends a MIBReset[ONT_Data](inst = 0) command. The ONU clears the MIB and autonomously creates a new MIB containing various Management Entities (MEs). The ONU responds with MIBReset_rsp[ONT_Data](inst = 0, success). The OLT then creates its own MIB with specific MEs. The ONU sends Attribute Value Change Notifications (AVCNs) for ANY_ME. The OLT sets attributes of the OLT ME in the ONU. The OLT sends a Set_cmd[OLT_ME](inst, attr mask, attribute) command. The ONU executes the command and updates its MIB and data sync. Finally, the ONU responds with Set_rsp[OLT_ME](inst, success).](9bd5073900339d75c2f66243d037e6e0_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + + Note left of OLT: After ranging, the OLT accepts the ONU as "new", i.e. a new PON id is assigned to its serial number. + Note left of OLT: The OLT clears the MIB of the ONU. + Note right of ONU: The ONU checks whether it contains a MIB (MIB data sync > 0). +If not, it creates the ONT-G, ONT Data and OLT managed entities. + + OLT->>ONU: MIBReset[ONT_Data](inst = 0) + Note right of ONU: The ONU clears the MIB. +The ONU autonomously creates a MIB containing: +one instance of the ONT-G ME, id = 0, +one instance of the ONT Data ME, id = 0, +one instance of the OLT ME, id = 0, +two instances Software Image ME, id = {0.0, 0.1}, +N instances of the Cardholder ME for PON IF, and +M instances of the Cardholder ME for UNI. +The ONU responds to the Reset command. + ONU->>OLT: MIBReset_rsp[ONT_Data](inst = 0, success) + Note left of OLT: .The OLT creates a MIB, data sync = 0, containing: +one instance of the ONT-G ME, id = 0. +one instance of the ONT Data ME, id = 0. +two instances of the Software Image ME, id = {0.0...0.1}. + Note right of ONU: The ONU may send AVCs as ME attributes are being populated but the OLT must still audit the ONU immediately after a Reset is completed. + ONU->>OLT: Attribute Value Change Notification[ANY_ME](inst, attr mask, attr) + Note left of OLT: .The OLT sets the attributes of the OLT ME in the ONU to match the OLT information. + OLT->>ONU: Set_cmd[OLT_ME](inst, attr mask, attribute) + Note right of ONU: ONU Executes command. +ONU updates the MIB and its MIB data sync. + ONU->>OLT: Set_rsp[OLT_ME](inst, success) + +``` + +Sequence diagram showing the start-up of a 'new' ONT with cardholders on both sides. The diagram involves two main entities: OLT and ONU. The process starts with the OLT accepting the ONU as 'new' and clearing its MIB. The ONU checks for a MIB; if not present, it creates the ONT-G, ONT Data, and OLT managed entities. The OLT sends a MIBReset[ONT\_Data](inst = 0) command. The ONU clears the MIB and autonomously creates a new MIB containing various Management Entities (MEs). The ONU responds with MIBReset\_rsp[ONT\_Data](inst = 0, success). The OLT then creates its own MIB with specific MEs. The ONU sends Attribute Value Change Notifications (AVCNs) for ANY\_ME. The OLT sets attributes of the OLT ME in the ONU. The OLT sends a Set\_cmd[OLT\_ME](inst, attr mask, attribute) command. The ONU executes the command and updates its MIB and data sync. Finally, the ONU responds with Set\_rsp[OLT\_ME](inst, success). + +Figure I.2.1-1 – Start-up of a "new" ONT with cardholders on both sides + +![Sequence diagram showing the start-up phase of a 'new' ONT with integrated interfaces on both sides. The diagram involves two main entities: OLT and ONU. The process starts with the OLT accepting the ONU as 'new' and clearing its MIB. The ONU checks for a MIB; if not present, it creates default entities. The OLT sends a MIBReset[ONT_Data](inst = 0) command. The ONU clears its MIB and autonomously creates a new one with specific Management Entities (MEs): one ONT-G ME, one ONT Data ME, one OLT ME, two Software Image MEs, M instances of ANI/PON PPTP/PONTC Adaptor, N instances of UNI/PPTP/TC Adaptor, P instances of US Priority Queue, and Q instances of DS Priority Queue. The ONU responds with MIBReset_rsp[ONT_Data](inst = 0, success). The OLT then creates its own MIB with ONT-G ME, ONT Data ME, and Software Image ME. The ONU sends Attribute Value Change Notifications (AVCNs) for ANY_ME. The OLT sets attributes of the OLT ME in the ONU. The OLT sends Set_cmd[OLT_ME](inst, attr mask, attr). The ONU executes the command and updates its MIB and data sync. Finally, the OLT receives Set_rsp[OLT_ME](inst, success).](397e865c06d592df17ba0409a792aa29_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + + Note left of OLT: After ranging, the OLT accepts the ONU as "new", i.e. a new PON id is assigned to its serial number. + Note left of OLT: The OLT clears the MIB of the ONU. + + Note right of ONU: The ONU checks whether it contains a MIB (MIB data sync > 0). +If not, it creates the ONT-G, ONT Data and OLT managed entities. + + OLT->>ONU: MIBReset[ONT_Data](inst = 0) + Note right of ONU: The ONU clears the MIB. +The ONU autonomously creates a MIB containing: +one instance of the ONT-G ME, id = 0. +one instance of the ONT Data ME, id = 0. +one instance of the OLT ME, id = 0. +two instances Software Image ME, id = {0.0, 0.1}. +M instances of the ANI, PON PPTP, and PONTC Adaptor with instance ids = {128, 1..M} +N instances of the UNI, PPTP and TC Adaptor, with instance ids = {0, 1..N}. +P instances US Priority Queue, instance is = 0..P-1. +Q instances of the DS Priority Queue, instance ids = 0..Q-1 +The ONU responds to the Reset command. + + ONU->>OLT: MIBReset_rsp[ONT_Data](inst = 0, success) + Note left of OLT: .The OLT creates a MIB, data sync = 0, containing: +one instance of the ONT-G ME, id = 0. +one instance of the ONT Data ME, id = 0. +two instances of the Software Image ME, id = {0.0...0.1}. + + ONU->>OLT: Attribute Value Change Notification[ANY_ME](inst, attr mask, attr) + Note right of ONU: The ONU may send AVCs as ME attributes are being populated but the OLT must still audit the ONU immediately after a Reset is completed. + + Note left of OLT: .The OLT sets the attributes of the OLT ME in the ONU to match the OLT information. + + OLT->>ONU: Set_cmd[OLT_ME](inst, attr mask, attr) + Note right of ONU: ONU Executes command. +ONU updates the MIB and its MIB data sync. + + ONU->>OLT: Set_rsp[OLT_ME](inst, success) + +``` + +Sequence diagram showing the start-up phase of a 'new' ONT with integrated interfaces on both sides. The diagram involves two main entities: OLT and ONU. The process starts with the OLT accepting the ONU as 'new' and clearing its MIB. The ONU checks for a MIB; if not present, it creates default entities. The OLT sends a MIBReset[ONT\_Data](inst = 0) command. The ONU clears its MIB and autonomously creates a new one with specific Management Entities (MEs): one ONT-G ME, one ONT Data ME, one OLT ME, two Software Image MEs, M instances of ANI/PON PPTP/PONTC Adaptor, N instances of UNI/PPTP/TC Adaptor, P instances of US Priority Queue, and Q instances of DS Priority Queue. The ONU responds with MIBReset\_rsp[ONT\_Data](inst = 0, success). The OLT then creates its own MIB with ONT-G ME, ONT Data ME, and Software Image ME. The ONU sends Attribute Value Change Notifications (AVCNs) for ANY\_ME. The OLT sets attributes of the OLT ME in the ONU. The OLT sends Set\_cmd[OLT\_ME](inst, attr mask, attr). The ONU executes the command and updates its MIB and data sync. Finally, the OLT receives Set\_rsp[OLT\_ME](inst, success). + +Figure I.2.1-2 – Start-up phase of a "new" ONT with integrated interfaces on both sides + +![Sequence diagram showing the start-up phase of an 'old' ONT between an OLT and an ONU. The OLT accepts the ONU as 'old' after ranging, starts a MIB audit, sends a Get_cmd for MIB Data sync, receives a Get_rsp, and then compares the data. The ONU checks for a valid MIB and configures itself if found.](e488c90b7f1a3c764cf9b50918f1ca6d_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: After ranging, the OLT accepts the ONU as "old", i.e. a PON id was already assigned to its serial number. + Note left of OLT: The OLT starts a MIB audit by getting the MIB data sync + OLT->>ONU: Get_cmd[ONT_Data](inst = 0, attr mask = MIB Data sync) + ONU-->>OLT: Get_rsp[ONT_Data](inst = 0, success, attr mask, attr data) + Note left of OLT: If, after comparison, the MIB data sync do not match, the OLT will start a MIB resynchronization process. + Note right of ONU: The ONU checks whether it contains a MIB (MIB data sync > 0). If a valid MIB is present, the ONU autonomously configures the system. + +``` + +Sequence diagram showing the start-up phase of an 'old' ONT between an OLT and an ONU. The OLT accepts the ONU as 'old' after ranging, starts a MIB audit, sends a Get\_cmd for MIB Data sync, receives a Get\_rsp, and then compares the data. The ONU checks for a valid MIB and configures itself if found. + +Figure I.2.1-3 – Start-up phase of an "old" ONT + +#### I.2.2 Circuit pack provisioning/de-provisioning + +The provisioning and de-provisioning of a circuit pack can be triggered in two ways: + +- on demand by the OpS; +- plug-and-play, triggered by detection of the card insertion/removal. + +However, this trigger of provisioning and de-provisioning is transparent to the ONT, i.e., the ONT always responds to OLT provisioning and de-provisioning commands. The difference between plug-and-play mode and on-demand mode would reside in the OLT. For the on-demand mode, the OLT provisions (de-provisions) the presence of the circuit pack in the ONT when it has been provisioned (de-provisioned) by the operator; for the plug-and-play mode, the OLT provisions the slot to "plug-and-play" and further provisions (de-provisions) the presence of the circuit pack in the ONT as soon as it has received a notification from the ONT that a circuit pack has been plugged in (out). + +#### I.2.3 On-demand circuit pack provisioning + +NOTE – It is possible to provision a circuit pack while a circuit pack of the same or of a different type is provisioned for the cardholder. In case a circuit pack of the same type is already provisioned, the provisioned command will have no effect. In case a circuit pack of a different type is already provisioned, this circuit pack will be automatically de-provisioned and only then the system will be configured according to the newly given plug-in unit type. Figures I.2.3-1 to I.2.3-3 show the scenarios of provisioning a circuit pack. + +The cases below show the use of the attributes "expected type" and "actual type" of the corresponding physical path termination points. + +##### Case 1 + +The subscriber cardholder or the ONT itself (the latter in case of integrated interfaces) only supports a specific type of interface. Notice that in the former case, the attribute "type" of the circuit pack managed entity will be equal to this type. + +In this case, on creation of the physical path termination point managed entity instance, the attributes "expected plug-in unit type" and "actual plug-in unit type" of the subscriber linecard holder managed entity are both set equal to the specific interface type and the ONT sends attribute value change notifications to the OLT with the values of these attributes. It will not be possible for + +the OLT to change the value of the attribute "expected plug-in unit type" later on (i.e., any attempt by the OLT to change the value of the attribute will be refused by the ONT). + +##### Case 2 + +The cardholder or the ONT itself (the latter in case of integrated interfaces) supports interfaces of different types. + +In this case, on creation of the physical path termination point managed entity instance, the attribute "expected plug-in unit type" is set to plug-and-play (0xFF) and the attribute "actual plug-in unit type" is set to: + +- inapplicable or unknown if the interface does not support plug-and-play or if the plug-and-play fails (actually, the coding is 0xFF in both cases); +- the sensed type if the interface supports autosensing and the autosensing was successful. + +The ONT will send an attribute value change notification with the values of these attributes. + +Later on, it will be possible for the OLT to change the value of attribute "expected plug-in unit type" with the "set" action. The value of attribute "actual type" will be set equal to the value of attribute "expected type". Notice however that the ONT will only execute the "set" action if the ONT supports the configured interface type. + +![Sequence diagram showing OLT and ONU interaction for circuit pack provisioning. The OLT provisions a LIM, sends a Set_cmd[Cardholder], and receives a Set_rsp[Cardholder](success). The ONU creates default instances and increments its MIB data sync. The OLT updates its MIB and increments its MIB data sync. The ONU detects that no Circuit pack is present. The OLT might want to modify attributes of the Circuit pack. The OLT sends a Set_cmd[Circuit pack](inst, attr mask, attr=value) and receives a Set_rsp[Circuit pack](success). The ONU updates the MIB and increments the MIB data sync. The OLT updates its MIB and increments its MIB data sync.](8974a4fe7cbc8391c913ae9925b88955_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT provisions the presence of a LIM + OLT->>ONU: Set_cmd[Cardholder](expected Plug-in type = value) + Note right of ONU: The ONT automatically creates: +•One instance of Circuit pack with default attributes, +•Two instances of Software Image +•N instances of the PPTP, UNI, and TC adaptor, where N is the number of ports, +•M instances of downstream priority queues.. +The ONT increments the MIB data sync. + ONU->>OLT: Set_rsp[Cardholder](success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + Note right of ONU: The ONT detects that no Circuit pack is present. + OLT->>ONU: Alarm[Cardholder](Plugin missing on) + Note left of OLT: The OLT might want to modify attributes of the Circuit pack . + OLT->>ONU: Set_cmd[Circuit pack](inst, attr mask, attr=value) + Note right of ONU: The ONT updates the MIB and increments the MIB data sync. + ONU->>OLT: Set_rsp[Circuit pack](success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + +``` + +Sequence diagram showing OLT and ONU interaction for circuit pack provisioning. The OLT provisions a LIM, sends a Set\_cmd[Cardholder], and receives a Set\_rsp[Cardholder](success). The ONU creates default instances and increments its MIB data sync. The OLT updates its MIB and increments its MIB data sync. The ONU detects that no Circuit pack is present. The OLT might want to modify attributes of the Circuit pack. The OLT sends a Set\_cmd[Circuit pack](inst, attr mask, attr=value) and receives a Set\_rsp[Circuit pack](success). The ONU updates the MIB and increments the MIB data sync. The OLT updates its MIB and increments its MIB data sync. + +**Figure I.2.3-1 – Circuit pack provisioning – Empty slot** + +![Sequence diagram showing circuit pack provisioning between OLT and ONU. The OLT provisions a LIM, sends a Set_cmd, receives a success response, updates its MIB, and then receives an alarm indicating a circuit pack type mismatch, finally updating its MIB again.](f4b7c84516339d37b6c63b18287d1493_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT provisions the presence of a LIM. + OLT->>ONU: Set_cmd[Cardholder](expected Plug-in type = value) + Note right of ONU: The ONT automatically creates: +•One instance of Circuit Pack with default attributes, +•Two instances of Software Image, +•N instances of the PPTP, UNI, and TC adaptor, where N is the number of ports, +•M instances of downstream priority queues. +The ONT increments the MIB data sync. + ONU->>OLT: Set_rsp[Cardholder](success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + Note right of ONU: The ONT detects that the Circuit pack is of the incorrect type. + ONU->>OLT: Alarm[Cardholder](PluginLIM mismatch on) + Note left of OLT: The OLT updates its MIB. + +``` + +The diagram illustrates the interaction between an OLT and an ONU during circuit pack provisioning. It begins with the OLT provisioning the presence of a LIM. The OLT then sends a `Set_cmd[Cardholder](expected Plug-in type = value)` message to the ONU. The ONU automatically creates several instances: one instance of Circuit Pack with default attributes, two instances of Software Image, N instances of the PPTP, UNI, and TC adaptor (where N is the number of ports), and M instances of downstream priority queues. The ONT increments the MIB data sync. The ONU responds with `Set_rsp[Cardholder](success)`. The OLT updates its MIB and increments its MIB data sync. The ONT detects that the Circuit pack is of the incorrect type. The ONU sends an `Alarm[Cardholder](PluginLIM mismatch on)` message to the OLT. Finally, the OLT updates its MIB. + +Sequence diagram showing circuit pack provisioning between OLT and ONU. The OLT provisions a LIM, sends a Set\_cmd, receives a success response, updates its MIB, and then receives an alarm indicating a circuit pack type mismatch, finally updating its MIB again. + +**Figure I.2.3-2 – Circuit pack provisioning – Incorrect circuit pack type detected** + +![Sequence diagram showing circuit pack provisioning between OLT and ONU. The process involves provisioning a LIM, sending a Set_cmd[Cardholder], automatic ONT creation of entities, a success response, MIB updates, card-specific data retrieval, a note about AVCs, potential attribute modification, a Set_cmd[ANY_ME], and a final success response with MIB updates.](1aefdc5d3828244fced02efe1771bc96_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT provisions the presence of a LIM. + OLT->>ONU: Set_cmd[Cardholder](expected Plug-in type = value) + Note right of ONU: The ONT automatically creates: +•One instance of Circuit pack with default attributes, +•Two instances of Software Image, +•N instances of the PPTP, UNI, and TC adaptor, where N is the number of ports, +•M instances of downstream priority queues. +The ONT increments the MIB data sync. + ONU->>OLT: Set_rsp[Cardholder](success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + Note right of ONU: The ONT retrieves card specific data + Note center: The ONU should send AVCs as ME attributes are being populated but the OLT must still audit the ONU immediately after an installed line card is provisioned. + Note left of OLT: The OLT might want to modify attributes of the Circuit pack and associated entities + OLT->>ONU: Set_cmd[ANY_ME](inst, attr mask, attr=value) + Note right of ONU: The ONT updates the MIB and increments the MIB data sync. + ONU->>OLT: Set_rsp[ANY_ME](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + +``` + +Sequence diagram showing circuit pack provisioning between OLT and ONU. The process involves provisioning a LIM, sending a Set\_cmd[Cardholder], automatic ONT creation of entities, a success response, MIB updates, card-specific data retrieval, a note about AVCs, potential attribute modification, a Set\_cmd[ANY\_ME], and a final success response with MIB updates. + +**Figure I.2.3-3 – Circuit pack provisioning – Card-specific data update** + +#### I.2.4 On-demand circuit pack de-provisioning + +The ONT will delete from the MIB all managed entities that it automatically created during the provisioning of this circuit pack. On the other hand, the OLT will be responsible for deleting all those managed entities that are associated with this card and were created by the OLT. Figures I.2.4-1 to I.2.4-3 show the process of de-provisioning a circuit pack. + +![Sequence diagram showing circuit pack de-provisioning between OLT and ONU. The OLT sends a Set_cmd[Cardholder] message to the ONU. The ONU responds with Set_rsp[Cardholder](inst, success). The OLT updates its MIB and increments its MIB data sync. The ONU detects that no circuit pack is present and sends an Alarm[Cardholder](inst, Plugin missing off) message to the OLT.](831c19022658f416cb09b881629c2574_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT de-provisions the presence of a LIM. + OLT->>ONU: Set_cmd[Cardholder](inst, expected Plug-in type = noLIM) + Note right of ONU: The ONT automatically deletes associated instances of: +•Circuit Pack, +•Software Image, +•N instances of the PPTP, UNI, and TC adaptor, where N is the number of ports, +•M instances of downstream priority queues. +The ONT increments the MIB data sync + ONU->>OLT: Set_rsp[Cardholder](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync + Note right of ONU: The ONT detects that no circuit pack is present + ONU->>OLT: Alarm[Cardholder](inst, Plugin missing off) + +``` + +Sequence diagram showing circuit pack de-provisioning between OLT and ONU. The OLT sends a Set\_cmd[Cardholder] message to the ONU. The ONU responds with Set\_rsp[Cardholder](inst, success). The OLT updates its MIB and increments its MIB data sync. The ONU detects that no circuit pack is present and sends an Alarm[Cardholder](inst, Plugin missing off) message to the OLT. + +**Figure I.2.4-1 – Circuit pack de-provisioning – Empty slot** + +![Sequence diagram showing OLT and ONU interaction for circuit pack de-provisioning. The OLT sends a Set_cmd[Cardholder] with expected Plug-in type = noLIM. The ONU responds with Set_rsp[Cardholder](inst, success). The OLT updates its MIB. The ONU detects an incorrect circuit pack type and sends an Alarm[Cardholder] with PluginLIM mismatch off.](c9f6ac4ecf497148f284abd1613d353e_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT deprovisions the presence of a LIM + OLT->>ONU: Set_cmd[Cardholder](inst, expected Plug-in type = noLIM) + Note right of ONU: The ONT automatically deletes associated instances of : +•Circuit Pack +•Software Image +•PPTP, UNI, and TC adaptor +•Downstream priority queues +The ONT increments the MIB data sync + ONU->>OLT: Set_rsp[Cardholder](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync + Note right of ONU: The ONT detects that the Circuit pack was of the incorrect type + ONU->>OLT: Alarm[Cardholder](inst, PluginLIM mismatch off) + +``` + +Sequence diagram showing OLT and ONU interaction for circuit pack de-provisioning. The OLT sends a Set\_cmd[Cardholder] with expected Plug-in type = noLIM. The ONU responds with Set\_rsp[Cardholder](inst, success). The OLT updates its MIB. The ONU detects an incorrect circuit pack type and sends an Alarm[Cardholder] with PluginLIM mismatch off. + +**Figure I.2.4-2 – Circuit pack de-provisioning – Incorrect circuit pack type detected** + +![Sequence diagram showing OLT and ONU interaction for circuit pack de-provisioning. The OLT sends a Set_cmd[Cardholder] message to the ONU. The ONU responds with Set_rsp[Cardholder](inst, success). The OLT updates its MIB and increments its MIB data sync. The ONU automatically deletes associated instances of Circuit Pack, Software Image, PPTP, UNI, and TC adaptor, and increments its MIB data sync. The ONU sends no alarm notifications and blocks all traffic on the line card.](b12888c1d6957245d70f09798a69a807_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT deprovisions the presence of a LIM + OLT->>ONU: Set_cmd[Cardholder](inst, expected Plug-in type = noLIM) + Note right of ONU: The ONT automatically deletes associated instances of : +•Circuit Pack +•Software Image +•PPTP, UNI, and TC adaptor +•Downstream priority queues +The ONT increments the MIB data sync + ONU->>OLT: Set_rsp[Cardholder](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync + Note right of ONU: The ONU sends no alarm notifications. The ONT will block all traffic on the line card + +``` + +Sequence diagram showing OLT and ONU interaction for circuit pack de-provisioning. The OLT sends a Set\_cmd[Cardholder] message to the ONU. The ONU responds with Set\_rsp[Cardholder](inst, success). The OLT updates its MIB and increments its MIB data sync. The ONU automatically deletes associated instances of Circuit Pack, Software Image, PPTP, UNI, and TC adaptor, and increments its MIB data sync. The ONU sends no alarm notifications and blocks all traffic on the line card. + +**Figure I.2.4-3 – Circuit pack de-provisioning – No alarm notifications** + +#### I.2.5 Plug-and-play circuit pack provisioning + +A cardholder can be provisioned for a plug-and-play mode of operation (see Figure I.2.5-1). Figure I.2.5-1 shows the scenario for provisioning a slot for plug-and-play. + +![Sequence diagram showing plug-and-play circuit pack provisioning between OLT and ONU.](acbfa72d71d68d0c0cfa9a65623a2dc1_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT provisions a cardholder to plug-and-play + OLT->>ONU: Set_cmd[Cardholder](inst, expected Plug-in = plug&play) + Note right of ONU: The ONT updates expected plugin type attr. +The ONT increments the MIB data sync + ONU->>OLT: Set_rsp[Cardholder](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync + Note right of ONU: A circuit pack is inserted into the ONT + ONU->>OLT: AVC[Cardholder](actual plugin type=X) + Note left of OLT: The OLT updates its MIB. +The OLT creates a circuit pack of the type just inserted + OLT->>ONU: Create_cmd[Circuit Pack](inst, type=X) + Note right of ONU: The ONT automatically creates: +•One instance of Circuit Pack with default attributes +•Two instances of Software Image +•N instances of the PPTP, UNI, and TC adaptor, where N is the number of ports +•M instances of downstream priority queues +The ONT increments the MIB data sync + ONU->>OLT: Create_rsp[Circuit Pack](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. +``` + +The diagram illustrates the interaction between an OLT and an ONU for plug-and-play circuit pack provisioning. It begins with the OLT provisioning a cardholder to plug-and-play. The OLT sends a `Set_cmd[Cardholder](inst, expected Plug-in = plug&play)` message to the ONU. The ONU responds with `Set_rsp[Cardholder](inst, success)`. The OLT updates its MIB and increments its MIB data sync. Then, a circuit pack is inserted into the ONT. The ONU sends an `AVC[Cardholder](actual plugin type=X)` message to the OLT. The OLT updates its MIB and creates a circuit pack of the type just inserted. The OLT sends a `Create_cmd[Circuit Pack](inst, type=X)` message to the ONU. The ONU automatically creates the necessary components: one instance of Circuit Pack with default attributes, two instances of Software Image, N instances of the PPTP, UNI, and TC adaptor (where N is the number of ports), and M instances of downstream priority queues. The ONU increments the MIB data sync and sends a `Create_rsp[Circuit Pack](inst, success)` message to the OLT. The OLT updates its MIB and increments its MIB data sync. + +Sequence diagram showing plug-and-play circuit pack provisioning between OLT and ONU. + +Figure I.2.5-1 – Plug-and-play circuit pack provisioning + +Not shown in Figure I.2.5-1 are the notifications of the ONT due to incorrectly inserted circuit packs. + +#### I.2.6 Plug-and-play circuit pack de-provisioning + +When a circuit pack is removed from a cardholder, a notification is sent to the OLT. The OLT de-provisions the cardholder upon receiving the notification (see Figure I.2.6-1). + +![Sequence diagram of plug-and-play circuit pack de-provisioning between OLT and ONU.](81ccdbed11305b38b940dadef7068a0e_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT deletes a linecard + OLT->>ONU: Delete_cmd[Circuit Pack](inst) + Note right of ONU: The ONT automatically deletes associated instances of : +•Circuit Pack +•Software Image +•PPTP, UNI, and TC adaptor +•Downstream priority queues +The ONT increments the MIB data sync + ONU->>OLT: Delete_rsp[Circuit Pack](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync +``` + +The diagram illustrates the sequence of operations for plug-and-play circuit pack de-provisioning. It starts with the OLT deleting a linecard. The OLT then sends a `Delete_cmd[Circuit Pack](inst)` message to the ONU. Upon receiving this command, the ONU automatically deletes associated instances of the Circuit Pack, Software Image, PPTP, UNI, and TC adaptor, and Downstream priority queues. The ONU also increments its MIB data sync. Finally, the ONU sends a `Delete_rsp[Circuit Pack](inst, success)` message back to the OLT, which then updates its MIB and increments its MIB data sync. + +Sequence diagram of plug-and-play circuit pack de-provisioning between OLT and ONU. + +Figure I.2.6-1 – Plug-and-play circuit pack de-provisioning + +#### I.2.7 Software image download + +The download of a software image is based on a "segmented stop and wait" protocol; thus, the next segment can only be transmitted to the ONT if the previous segment is positively acknowledged. A software image segment (also named window) consists of one or more software image sections. Each section is transmitted in one OMCC message. + +The number of sections in a segment is negotiated before the actual download. First, the OLT proposes a segment size (not greater than 256). The ONT can propose a smaller segment size in the response. If the response indicates a smaller segment size, this is the size to be used in the download. Thus, an image segment consists of N image sections, with N being equal to the segment size. Only the last image section is acknowledged. If the ONT processed all sections of a segment properly, the acknowledgement will be positive, after which the OLT will download the next segment. + +Note that the section numbering starts from 0 so that segments of precisely 8 kilobytes can be downloaded. + +If an error occurred with a section of a segment (e.g., CRC error or missed section), the last section will be negatively acknowledged, which will result in an entire retransmission of the last segment. + +When the last segment transferred is positively acknowledged, the OLT sends a CRC-32 to the ONT in the software image end download command. The ONT calculates the CRC-32 and compares it to the CRC received from the OLT. If they are equal, the image is considered valid. Figure I.2.7-1 gives the scenario for the software download. + +![Sequence diagram of software download between OLT and ONU. The process involves a start command, a response with window size, a loop of section downloads, and an error handling mechanism.](ac3afa2e555b328432e17d1e942e1bf6_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: ONT puts the "is valid" attr. of the given Software Image instance to invalid. ONT updates the MIB data sync and responds with a window size. (If ONT requires smaller window size) + OLT->>ONU: Start_Software_Download_cmd[Software Image] (inst, window size-1, image size) + ONU-->>OLT: Start_Software_Download_Rsp[Software Image] (inst, success, window size-1) + Note left of OLT: OLT adopts the window size proposed by ONT. OLT updates its MIB and increments its MIB data sync + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number 0, image data) + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number 1, image data) + Note right of ONU: ONT receives a segment of software image. + ONU-->>OLT: Download_Section_rsp[Software Image](inst, success, section number) + Note left of OLT: OLT sends the next segment. + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number 0, image data) + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number 1, image data) + Note right of ONU: ONT detects error. + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number N, image data) + ONU-->>OLT: Download_Section_rsp[Software Image](inst, error message) + Note left of OLT: OLT sends the same segment again . + +``` + +The sequence diagram illustrates the software download process between an OLT and an ONU. It begins with the OLT sending a `Start_Software_Download_cmd` to the ONU. The ONU responds with `Start_Software_Download_Rsp`, and a note indicates that the ONT invalidates the current software image instance, updates its MIB data sync, and proposes a window size. The OLT then adopts this window size and updates its own MIB. The download proceeds in sections, with the OLT sending `Download_Section_cmd` messages for sections 0, 1, and N. The ONU receives these segments and responds with `Download_Section_rsp` messages indicating success. A note indicates the OLT sends the next segment. However, an error occurs during the download of subsequent sections (0, 1, and N), as indicated by a note on the ONU side. The ONU then sends an error message in the `Download_Section_rsp`, and the OLT responds by retransmitting the same segment. + +Sequence diagram of software download between OLT and ONU. The process involves a start command, a response with window size, a loop of section downloads, and an error handling mechanism. + +Figure I.2.7-1 – Software download + +### I.2.8 Software image activate and commit + +See Figure I.2.8-1. + +![Sequence diagram showing the software image activate and commit process between an OLT and an ONU.](f58d0ddf50366f1a6f8965187cae3988_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: OLT sends the last segment. + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number 0, image data) + Note right of ONU: ONT receives a segment of software image. + OLT->>ONU: Download_Section_cmd[Software Image](inst, section number N, image data) + ONU-->>OLT: Download_Section_rsp[Software Image](inst, success, section number) + OLT->>ONU: End_Software_Download_cmd[Software Image](inst, CRC32, image size) + Note right of ONU: ONT compares the received CRC32 with calculated CRC32. If they are equal, ONT puts the "is valid" attr of the given Software Image instance to valid. ONT updates the MIB data sync. + ONU-->>OLT: End_Software_Download_rsp[Software Image](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync + OLT->>ONU: Active_Image_cmd[Software Image](inst) + Note right of ONU: The ONT updates its MIB and increments its MIB data sync + ONU-->>OLT: Active_Image_rsp[Software Image](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync + Note left of OLT: OLT decides to commit the active software image after successful start up sequence. + OLT->>ONU: Commit_Image_cmd[Software Image](inst) + Note right of ONU: The ONT updates its MIB and increments its MIB data sync + ONU-->>OLT: Commit_Image_rsp[Software Image](inst, success) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync +``` + +The sequence diagram illustrates the interaction between an OLT and an ONU for software image activation and commit. The process begins with the OLT sending the last segment of the software image. The OLT then sends `Download_Section_cmd[Software Image](inst, section number 0, image data)` and `Download_Section_cmd[Software Image](inst, section number N, image data)` to the ONU. The ONU receives these segments and responds with `Download_Section_rsp[Software Image](inst, success, section number)`. The OLT then sends `End_Software_Download_cmd[Software Image](inst, CRC32, image size)`. The ONU compares the received CRC32 with the calculated CRC32. If they are equal, it sets the "is valid" attribute of the Software Image instance to valid and updates its MIB data sync. The ONU responds with `End_Software_Download_rsp[Software Image](inst, success)`. The OLT updates its MIB and increments its MIB data sync. The OLT then sends `Active_Image_cmd[Software Image](inst)`. The ONU updates its MIB and increments its MIB data sync and responds with `Active_Image_rsp[Software Image](inst, success)`. The OLT updates its MIB and increments its MIB data sync. The OLT then decides to commit the active software image after a successful start up sequence. The OLT sends `Commit_Image_cmd[Software Image](inst)`. The ONU updates its MIB and increments its MIB data sync and responds with `Commit_Image_rsp[Software Image](inst, success)`. The OLT updates its MIB and increments its MIB data sync. + +Sequence diagram showing the software image activate and commit process between an OLT and an ONU. + +Figure I.2.8-1 – Software activate and software commit + +# Appendix II + +## OMCI message set + +(This appendix does not form an integral part of this Recommendation) + +## II.1 General remarks + +#### II.1.1 Message type identifier + +The message types are given in clause 11.1.4. + +#### II.1.2 Entity class identifier + +The entity class identifiers are given in clause 11.1.6. + +#### II.1.3 Result and reason + +Responses to commands can indicate the result of the command. A value of "null" will indicate that the command was processed successfully. Non-null values will indicate the reason of the failure. If the result was "failure", the rest of the message contents will be filled with all 0x00s. The definition of each result and reason is as follows: + +##### 1) Command processed successfully + +There are two functions for command processing: command interpretation and command execution. This result means that the received command, such as get/set/test/reboot, was properly interpreted by the ONT's command interpretation function without errors and that the interpreted command was successfully transferred to the ONT's command execution function. + +##### 2) Command processing error + +This result means the command processing failed at the ONT due to some reason not described by item 3), 4), etc. + +##### 3) Command not supported + +This result means that the message type indicated in byte 8 is not supported by the ONT. + +##### 4) Parameter error + +This result means that the command message received by the ONT was errored. + +##### 5) Unknown managed entity + +This result means that the managed entity class indicated in bytes 10 and 11 is not supported by the ONT. + +##### 6) Unknown managed entity instance + +This result means that the managed entity instance indicated in bytes 12 and 13 does not exist in the ONT. + +##### 7) Device busy + +This result means that the command could not be processed due to process-related congestion at the ONT. + +##### 8) Attribute(s) failed or unknown + +This result means that an optional attribute is not supported by the ONT or that a mandatory/optional attribute could not be executed by the ONT, even if it is supported. In conjunction with this result, attribute masks are used to indicate which attributes failed or were unknown. + +The following two kinds of attribute masks are used when this result/reason is raised: + +- *optional attribute mask coding*, which indicates whether or not the optional attribute is supported; +- *attribute execution mask coding*, which indicates whether or not the mandatory/optional attribute was executed. + +See set response and get response message layouts (clauses II.2.10 and II.2.12) for the placement of these masks. + +If one or more optional attributes are not supported by the ONT, the "optional attribute mask coding" for each *unsupported* optional attribute becomes 1 while the corresponding "attribute execution mask coding" remains 0. + +If one or more mandatory or optional attributes were not executed by the ONT, the "optional attribute mask coding" remains 0, while the "attribute execution mask coding" becomes 1 for each *failed* attribute. + +##### 9) Instance exists + +This result means that the ONT already has a managed entity instance that corresponds to the one the OLT is attempting to create. + +#### II.1.4 Get, get response, create response and set messages + +For an attribute mask, a bit map is used in the get, get response, create response and set messages. This bit map indicates which attributes are requested (get) or provided (get response and set). The bit map is composed as follows: + +| Byte | Bit | | | | | | | | +|------|-------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------| +| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| 1 | Attribute 1 | Attribute 2 | Attribute 3 | Attribute 4 | Attribute 5 | Attribute 6 | Attribute 7 | Attribute 8 | +| 2 | Attribute 9 | Attribute 10 | Attribute 11 | Attribute 12 | Attribute 13 | Attribute 14 | Attribute 15 | Attribute 16 | + +The attribute numbers correspond to the ordering of the attributes in clause 9. Note that the managed entity identifier, which is an attribute of each managed entity, has no corresponding bit in the attribute mask. Thus, the attributes are counted starting from the first attribute after the managed entity identifier. + +#### II.1.5 Alarm notifications + +The ONT will send this notification each time an alarm status has changed for the entity indicated in the message identifier. The message shows the status of *all* alarms of this entity. It is up to the OLT to determine which alarm status has changed. + +The maximum number of alarms that is supported by the OMCI is 224 because of the available message field of get all alarm next message. The bit map is composed as follows: + +| Byte | Bit | | | | | | | | +|------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------| +| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| 1 | Alarm 0 | Alarm 1 | Alarm 2 | Alarm 3 | Alarm 4 | Alarm 5 | Alarm 6 | Alarm 7 | +| 2 | Alarm 8 | Alarm 9 | Alarm 10 | Alarm 11 | Alarm 12 | Alarm 13 | Alarm 14 | Alarm 15 | +| ... | | | | | | | | | +| 28 | Alarm 216 | Alarm 217 | Alarm 218 | Alarm 219 | Alarm 220 | Alarm 221 | Alarm 222 | Alarm 223 | + +The alarm numbers correspond to the alarm coding in clause 9. Bits in the alarm bit map that correspond to non-existing alarms shall always be set equal to 0. Bits that correspond to existing alarms are set to a value of 0 to indicate that the corresponding alarm is cleared, or a value of 1 to indicate that the alarm has been raised. + +Alarm message sequence numbers can take values in the interval 1 to 255. Zero is excluded in order to make this counter similar to the MIB data sync counter. + +#### II.1.6 Test, test response and test result + +The descriptions below indicate how test, test response and test result messages are related. + +Test: This message is used to initiate either a self test or any of the other specific tests defined against various managed entity types. + +Test response: This message is an immediate reaction to a test message. The test response message reports the ability of the ONT to run the required test, but it does not contain any specific results. + +Test result: This message is used to report the result of either a self test (requested by the OLT) or one of the specific tests defined against various managed entity types. The test result notification is not used for autonomous tests that produce only pass-fail results. Instead, notification is sent to the OLT via an alarm if the managed entity fails its autonomous self test. Autonomous tests on the ANI-G managed entity may, however, be reported with an autonomous test result message, with or without corresponding alarms, on grounds that the actual measured values may be important. + +A test on a particular managed entity instance is invoked by sending a test message to this instance. Each managed entity that supports tests needs to have an action test defined for it. The type of test invoked by a test message depends on the managed entity. + +The test response message is an indication to the OLT that the test request is received and is being processed. The results of a requested test are sent to the OLT via a specific test result message. + +The test response message is sent immediately after the test message is received (i.e., within the normal response time). The transaction identifier of the test response message is identical to the transaction identifier of the test message that requested the test. + +## II.2 Message layout + +#### II.2.1 Create + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = create | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | + +| Field | Byte | | | | | | | | | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------| +| | | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | +| Message contents | 14 | | | | | | | | | Attribute value of first set-by-create attribute, NOT the ME ID (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last set-by-create attribute (size depending on the type of attribute) | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +It should be noted that the message contents for the "create" message apply only to attributes that are defined to be "set-by-create". Writeable attributes that are not set-by-create are not permitted in a create message. Thus, the first byte of the message contents field begins with the attribute value for the first set-by-create attribute and so forth. Space for each set-by-create attribute must be allocated in the create message, even if the attribute is optional. When an optional attribute is not to be instantiated, the placeholder value to be entered into this space is specific to the definition of each attribute. + +#### II.2.2 Create response + +| Field | Byte | | | | | | | | | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = create | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy
0111 = instance exists | +| | 15 | | | | | | | | | Attribute execution mask (attributes 1-8), used with 0011 encoding:
0 = attribute ok
1 = illegal value attribute | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------| +| | 16 | | | | | | | | | Attribute execution mask
(attributes 9-16), used with 0011
encoding:
0 = attribute ok
1 = illegal value attribute | +| | 17-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +**II.2.3 This clause intentionally left blank** + +**II.2.4 This clause intentionally left blank** + +**II.2.5 Delete** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = delete | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +**II.2.6 Delete response** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = delete | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +**II.2.7 This clause intentionally left blank** + +**II.2.8 This clause intentionally left blank** + +**II.2.9 Set** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = set | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte attribute mask | +| | 15 | | | | | | | | | LS byte attribute mask | +| | 16 | | | | | | | | | Attribute value of first attribute to set (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last attribute to set (size depending on the type of attribute) | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +**II.2.10 Set response** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = set | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy
1001 = attribute(s) failed or unknown | +| | 15 | | | | | | | | | Optional attribute mask (attributes 1-8), used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 16 | | | | | | | | | Optional attribute mask (attributes 9-16), used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 17 | | | | | | | | | Attribute execution mask (attributes 1-8), used with 1001 encoding:
0 = default
1 = failed attribute | +| | 18 | | | | | | | | | Attribute execution mask (attributes 9-16), used with 1001 encoding:
0 = default
1 = failed attribute | +| | 19-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.11 Get + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte attribute mask | +| | 15 | | | | | | | | | LS byte attribute mask | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +Based on the size of the message contents field, the aggregate size of the attributes requested by a single get command should not exceed 25 bytes. + +#### II.2.12 Get response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy
1001 = attribute(s) failed or unknown | +| | 15 | | | | | | | | | MS byte attribute mask | +| | 16 | | | | | | | | | LS byte attribute mask | +| | 17 | | | | | | | | | Attribute value of first attribute included (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last attribute included (size depending on the type of attribute) | +| | xx-41 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | +| | 42 | | | | | | | | | Optional attribute mask (attributes 1-8), used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 43 | | | | | | | | | Optional attribute mask (attributes 9-16), used with 1001 encoding:
0 = default
1 = unsupported attribute | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------| +| | 44 | | | | | | | | | Attribute execution mask (attributes 1-8), used with 1001 encoding:
0 = default
1 = failed attribute | +| | 45 | | | | | | | | | Attribute execution mask (attributes 9-16), used with 1001 encoding:
0 = default
1 = failed attribute | + +Bytes 42 to 45 are always reserved for the optional attribute and attribute execution masks; however, the content of these bytes is only valid in conjunction with the 1001 encoding used to indicate failed or unknown attributes. + +When the ONT wishes to transfer an attribute whose size is or might be larger than the space available in one OMCI message, the ONT responds with four bytes to indicate the size of that attribute with an appropriate attribute mask. The OLT should then use the get next message in order to retrieve the attribute. + +#### **II.2.13 This clause intentionally left blank** + +#### **II.2.14 This clause intentionally left blank** + +#### **II.2.15 Get all alarms** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get all alarms | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = alarm retrieval mode
0 = Get all alarms regardless of ARC status
1 = Get all alarms not currently under ARC | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.16 Get all alarms response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get all alarms | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte of the number of subsequent commands | +| | 15 | | | | | | | | | LS byte of the number of subsequent commands | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.17 Get all alarms next + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get all alarms next | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte of the command sequence number | +| | 15 | | | | | | | | | LS byte of the command sequence number | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +The command sequence numbers shall start from 0x00 onwards. + +#### II.2.18 Get all alarms next response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get all alarms next | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------| +| Message contents | 14-15 | | | | | | | | | Entity class on which the alarms are reported | +| | 16 | | | | | | | | | MS byte entity instance on which the alarms are reported | +| | 17 | | | | | | | | | LS byte entity instance on which the alarms are reported | +| | 18-45 | x | x | x | x | x | x | x | x | Bit map alarms | + +The bit map used in the get all alarms next response for a given managed entity class is identical to the bit map used in the alarm notifications for that managed entity class. + +In the case where the ONT receives a get all alarms next request message in which the command sequence number is out of range, the ONT should respond with a message in which bytes 14 to 45 are all set to 0. This corresponds to a response with entity class 0, entity instance 0, and bit map all 0s. + +#### II.2.19 MIB upload + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB upload | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.20 MIB upload response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB upload | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte of the number of subsequent commands | +| | 15 | | | | | | | | | LS byte of the number of subsequent commands | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.21 MIB upload next + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB upload next | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte of the command sequence number | +| | 15 | | | | | | | | | LS byte of the command sequence number | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +The command sequence numbers shall start from 0 onwards. + +#### II.2.22 MIB upload next response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB upload next | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14-15 | | | | | | | | | Entity class of object | +| | 16 | | | | | | | | | MS byte entity instance of object | +| | 17 | | | | | | | | | LS byte entity instance of object | +| | 18 | | | | | | | | | MS byte attribute mask | +| | 19 | | | | | | | | | LS byte attribute mask | +| | 20 | | | | | | | | | Value of first attribute (size depending on the type of the attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of the last attribute (size depending on the type of the attribute) | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +If the ONT receives a MIB upload next request message in which the command sequence number is out of range, it should respond with a message in which bytes 14 to 45 are all set to 0. This corresponds to a response with entity class 0x0000, entity instance 0x0000, attribute mask 0x0000, and padding from byte 20 to byte 45. + +Note that, if all attributes of a managed entity do not fit within one MIB upload next response message, the attributes will be split over several messages. The OLT can use the information in the attribute mask to determine which attribute values are reported in which MIB upload next response message. + +#### II.2.23 MIB reset + +| Field | Byte | Bit | | | | | | | | Comments | +|------------------------|-------|-----|---|---|---|---|---|---|---|--------------------------------------------------------| +| | | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB reset | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.24 MIB reset response + +| Field | Byte | Bit | | | | | | | | Comments | +|------------------------|-------|-----|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB reset | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = ONT data | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MS byte entity instance | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.25 Alarm + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = alarm | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | Alarm mask | +| | | | | | | | | | | ... | +| | 41 | | | | | | | | | Alarm mask | +| | 42-44 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | +| | 45 | | | | | | | | | Alarm sequence number | + +#### II.2.26 Attribute value change + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = attribute value change | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte attribute mask | +| | 15 | | | | | | | | | LS byte attribute mask | +| | 16 | | | | | | | | | Attribute value of first attribute changed (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last attribute changed (size depending on the type of attribute) | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +NOTE – For table attributes, the AVC message will contain no attribute value (only a mask), and no snapshot of the table will be created. If the OLT wishes to obtain the new value, it will then do a get operation, followed by the required number of get next operations. + +#### II.2.27 Test + +The format of the test message is specific to the target entity class. At present, three formats are defined. Future test extensions for a given entity class can be supported by adding additional encodings to presently unused bits or bytes. Future specification of tests for other entity classes may use an existing format or may define new formats for the test message. These extension mechanisms allow future tests to be supported without changing the principle of operation. + +#### Format for ONT-G, ANI-G and circuit pack entity classes + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = test | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This format applies to entity classes ONT-G, ANI-G and circuit pack. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | xxxx = select test
0000..0110 reserved for future use
0111 = self test
1000..1111 vendor-specific use
See description related to the test result message. | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +##### Format for IP host config data entity class + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This format applies to entity class IP host config data. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 14 | 0 | 0 | 0 | 0 | x | x | x | x | xxxx = select test
0001 = Ping
0010 = Traceroute
0010..0111 Reserved
1000..1111 Vendor-specific use
The ICMP message is intended to be from the ONT upstream toward the network. See discussion related to the test result message. | +| | 15-18 | | | | | | | | | IP address of target | +| | 19-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +##### Format for POTS UNI and PPTP ISDN UNI entity classes + +This message supports two basic categories of test operation, a defined set of tests that look in and out from the POTS port, and a set of codepoints that may be used for vendor-specific tests. The latter category is further subdivided into codepoints that return test results in a general purpose buffer ME, using the test results message primarily as an event trigger to signal test completion, and codepoints that return all test results in an ordinary test result message. If it is needed, the OLT must create the general purpose buffer managed entity before initiating the test action. + +Note that a single message can be used to initiate multiple tests on a given ME if desired. + +Bytes 15-28 are used by the dial tone make-break test. A zero value for a timer causes the ONT to use its built-in defaults. As many as three dial tone frequencies can be specified, or omitted by setting their values to 0. Other fields are also omitted with the value 0, or controlled by flags. An ONT can support the dial tone test with internal defaults only, and is not required to support any of the attributes of bytes 15-28. Likewise, an ONT can use internal defaults for drop test, rather than the values given in bytes 29-38. The capabilities of an ONT are documented by the vendor and known through administrative practices. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This format applies to entity classes PPTP POTS UNI and PPTP ISDN UNI. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 14 | a | 0 | 0 | 0 | x | x | x | x | a – test mode
0 = normal; deny test if line busy
1 = forced mode
xxxx = select test
0000 = all MLT tests
0001 = hazardous potential
0010 = foreign EMF
0011 = resistive faults
0100 = receiver off-hook
0101 = ringer
0110 = NT1 dc signature test
0111 = self test
1000 = dial tone make-break test
1001..1011 = vendor-specific test,
all results returned in test results
message
1100..1111 is a vendor-specific test,
test results returned in general
purpose buffer ME. The ONT should
deny a test operation command in this
range if bytes 39-40 do not point to a
GP buffer. | +| | 15 | | | | | | | | | DBDT timer T1 (slow dial tone threshold), in units of 0.1 seconds. Range 0.1 to 6.0 seconds. | +| | 16 | | | | | | | | | DBDT timer T2 (no dial tone threshold), in units of 0.1 seconds. Range 1.0 to 10.0 seconds. | +| | 17 | | | | | | | | | DBDT timer T3 (slow break dial tone threshold), in units of 0.1 seconds. Range 0.1 to 3.0 seconds. | +| | 18 | | | | | | | | | DBDT timer T4 (no break dial tone threshold), in units of 0.1 seconds. Range 1.0 to 3.0 seconds. | +| | 19 | | | | | | | d | p | DBDT control byte
d: dialled digit
1 = dialled digit specified in
byte 20
0 = use default digit
p = pulse (1) or tone (0) dialling | +| | 20 | | | | | | | | | Digit to be dialled, ASCII character in range "0"-"9", "*", "#". | +| | 21-22 | | | | | | | | | Dial tone frequency 1, in units of Hz | +| | 23-24 | | | | | | | | | Dial tone frequency 2, in units of Hz. 0 = unused (i.e., if only one tone is specified). | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|--------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------| +| | | | | | | | | | | | +| | 25-26 | | | | | | | | | Dial tone frequency 3, in units of Hz. 0 = unused (i.e., if only one or two tones are specified). | +| | 27 | | | | | | | | | Dial tone power threshold, absolute value, 0.1 dB resolution, range $[-]0.1$ to $[-]25.3$ dBm0, e.g., -13 dBm0 = 0x82. 0x00 = unspecified. | +| | 28 | | | | | | | | | Idle channel power threshold, absolute value, 1 dB resolution, range $[-]1$ to $[-]90$ dBm0. 0x00 = unspecified. | +| | 29 | | | | | | | | | DC hazardous voltage threshold, absolute value, volts 0x00 = unspecified. | +| | 30 | | | | | | | | | AC hazardous voltage threshold, volts RMS 0x00 = unspecified | +| | 31 | | | | | | | | | DC foreign voltage threshold, absolute value, volts 0x00 = unspecified | +| | 32 | | | | | | | | | AC foreign voltage threshold, volts RMS 0x00 = unspecified | +| | 33 | | | | | | | | | Tip-ground and ring-ground resistance threshold, kΩ 0x00 = unspecified | +| | 34 | | | | | | | | | Tip-ring resistance threshold, kΩ 0x00 = unspecified | +| | 35-36 | | | | | | | | | Ringer equivalence minimum threshold, in 0.01 REN units 0x00 = unspecified | +| | 37-38 | | | | | | | | | Ringer equivalence maximum threshold, in 0.01 REN units 0x00 = unspecified. | +| | 39..40 | | | | | | | | | Pointer to a general purpose buffer ME, used to return vendor-specific test results | +| | 41-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.28 Test response + +If an ONT does not support all tests requested in byte 14 of the test message, it should not execute any test and should respond with result 0010, command not supported. If an ONT supports all of the requested tests but cannot support one or more of the explicitly specified threshold attributes, it should not execute any test and should respond with result 0011, parameter error. The test command could then be re-issued with different thresholds or default thresholds, and would be expected to succeed. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = test | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +The test response message is an indication to the OLT that the test request is received and is being processed. + +#### II.2.29 Start software download + +When a file is to be downloaded to a single instance of the software image managed entity, the ME id is specified in bytes 12..13. An optional feature permits the same file to be downloaded to a number of circuit packs by setting bytes 12..13 = 0xffff and specifying the software image ME ids in bytes 20..21, etc. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = start software download | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte of software image instance
0 = ONT-G
1..254 = slot number
255 = download to multiple software image managed entities | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------| +| | 13 | | | | | | | | | LS byte of software image instance
0 = instance 0
1 = instance 1
255 = multiple download | +| Message contents | 14 | | | | | | | | | Window size – 1 | +| | 15-18 | | | | | | | | | Image size in bytes | +| | 19 | | | | | | | | | Number of circuit packs to be updated in parallel (value 1...9) | +| | 20 | | | | | | | | | MS byte of software image instance (slot number of circuit pack) | +| | 21 | | | | | | | | | LS byte of software image instance (value 0..1) | +| | 22-xx | | | | | | | | | Software image ME ids (same format as bytes 20..21) for additional simultaneous downloads | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.30 Start software download response + +When a file is downloaded to a single software image ME, the response contains the target ME id in bytes 12..13, a result code in byte 14, a window size counter-proposal (which may be the same as that suggested by the OLT in the original request), and 0 padding for the remaining bytes. + +An ONT that supports the optional parallel download feature responds with the full format shown below. If the ONT does not support the parallel download feature, it responds with the code 0b0101, unknown managed entity instance. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = start software download | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte of software image instance
0 = ONT-G
1..254 = slot number
255 = download to multiple software image managed entities | +| | 13 | | | | | | | | | LS byte of software image instance
0 = instance 0
1 = instance 1
255 = multiple download | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15 | | | | | | | | | Window size – 1 | +| | 16 | | | | | | | | | Number of instances responding (value 0..9) | +| | 17-18 | | | | | | | | | ME id of software image entity instance (slot number plus instance 0..1) | +| | 19 | | | | | | | | | Result, reason for bytes 17..18 – same coding as byte 14 | +| | 20-xx | | | | | | | | | Repeat coding of bytes 17..19 for additional requested software image instances | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.31 Download section + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | x | 0 | | | | | | DB = 0, AR = x, AK = 0
x = 0: no response expected (section within the window)
x = 1: response expected (last section of a window)
bits 5-1: action = sw download section | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte of software image instance
0 = ONT-G
1..254 = slot number
255 = download to multiple software image managed entities | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------| +| | 13 | | | | | | | | | LS byte of software image instance
0 = instance 0
1 = instance 1
255 = multiple download | +| Message contents | 14 | | | | | | | | | Download section number | +| | 15-45 | | | | | | | | | Data; 0 padding if final transfer requires only a partial block | + +#### II.2.32 Download section response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = sw download section | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte of software image instance
0 = ONT-G
1..254 = slot number
255 = download to multiple software image managed entities | +| | 13 | | | | | | | | | LS byte of software image instance
0 = instance 0
1 = instance 1
255 = multiple download | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15 | | | | | | | | | Download section number | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.33 End software download + +The format of this command is similar to that of the start software download message. Bytes 22..N support the optional parallel download feature, and are set to 0 for download to a single target. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = end software download | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte of software image instance
0 = ONT-G
1..254 = slot number
255 = download to multiple software image managed entities | +| | 13 | | | | | | | | | LS byte of software image instance
00 = instance 0
01 = instance 1
255 = multiple download | +| Message contents | 14-17 | | | | | | | | | CRC-32 | +| | 18-21 | | | | | | | | | Image size in bytes | +| | 22 | | | | | | | | | Number of parallel download instances sent in this message (value 1..9) | +| | 23 | | | | | | | | | MS byte of software image instance (slot number of circuit pack) | +| | 24 | | | | | | | | | LS byte of software image instance (value 0..1) | +| | 25-xx | | | | | | | | | Software image ME ids (same format as bytes 23..24) for additional simultaneous downloads | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.34 End software download response + +The response message informs the OLT whether the download command was successful. If a single software image ME was targeted for download, byte 14 reports the result of the process. If a number of software images were targeted for parallel download, byte 14 reports device busy as long as any of the instances is busy writing the image to non-volatile store. Once the ONU has stored all images successfully, it responds with a 0 in byte 14 and a separate result for each software image ME. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = end software download | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte of software image instance
0 = ONT-G
1..254 = slot number
255 = download to multiple software image managed entities | +| | 13 | | | | | | | | | LS byte of software image instance
00 = instance 0
01 = instance 1
255 = multiple download | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully (CRC correct)
0001 = command processing error (CRC incorrect)
0010 = command not supported (not applicable)
0011 = parameter error (not applicable)
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15 | | | | | | | | | Number of instances responding (value 0..9) | +| | 16-17 | | | | | | | | | ME id of software image entity instance (slot number plus instance 0..1) | +| | 18 | | | | | | | | | Result, reason for bytes 16..17 – same coding as byte 14 | +| | 19-42 | | | | | | | | | Repeat coding of bytes 16..18 for additional software image instances | +| | 43-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.35 Activate image + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = activate image | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte entity instance
0 = ONT-G
1, 2, ..., 254 = slot number | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | LS byte entity instance
00 = first instance
01 = second instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.36 Activate image response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = activate image | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte entity instance
0 = ONT-G
1, 2, ..., 254 = slot number | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | LS byte entity instance
00 = first instance
01 = second instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.37 Commit image + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = commit image | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte entity instance
0 = ONT-G
1, 2, ..., 254 = slot number | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | LS byte entity instance
00 = first instance
01 = second instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.38 Commit image response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = commit image | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class = software image | +| | 12 | | | | | | | | | MS byte entity instance
0 = ONT-G
1, 2, ..., 254 = slot number | +| | 13 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | LS byte entity instance
00 = first instance
01 = second instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.39 Synchronize time + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = synchronize time | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.40 Synchronize time response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
Bits 5-1: action = synchronize time | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.41 Reboot + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = reboot | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +#### II.2.42 Reboot response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = reboot | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15-45 | | | | | | | | | Padding | + +#### II.2.43 Get next + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get next | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte attribute mask | +| | 15 | | | | | | | | | LS byte attribute mask | +| | 16 | | | | | | | | | MS byte of the command sequence number | +| | 17 | | | | | | | | | LS byte of the command sequence number | +| | 18-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +The command sequence numbers shall start from 0 onwards. + +#### II.2.44 Get next response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get next | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy | +| | 15 | | | | | | | | | MS byte attribute mask | +| | 16 | | | | | | | | | LS byte attribute mask | +| | 17 | | | | | | | | | Attribute value (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value (size depending on the type of attribute) | +| | xx-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +If the ONT receives a get next request message in which the command sequence number is out of range, the ONT shall respond with parameter error. + +#### II.2.45 Test result + +The test result message is used to report the result of a test. In the case of a requested test, the transaction identifier of the test result message is identical to the transaction identifier of the test message that initiated the corresponding test. In the case of a self-triggered test result, the transaction identifier is set to 0. + +Several formats are currently defined. They are used as follows: + +- Self test results, ONT-G, circuit pack, or any other ME that supports self test. +- Vendor-specific test results, generic format, any ME that supports it. +- POTS (or BRI) test results, either MLT, dial tone draw-break or vendor-specific POTS tests that use a general purpose buffer. +- ICMP tests, either ping or traceroute. +- The results of an optical line supervision test on the ANI-G. + +If a new test for the presently-supported entities is defined in the future, the corresponding test results can be reported by extending the test result message layout. If a new test for other managed entity classes is defined in the future, a new test result message layout may be defined. + +##### Format for self test action invoked against ONT-G and circuit pack entity classes + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This message format pertains to ONT-G and circuit pack entity classes. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Unused | +| | 15 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | Self test result:
xx = 00: failed
xx = 01: passed
xx = 10: not completed | +| | 15-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +##### Format for vendor-specific test actions invoked against ONT-G and circuit pack entity classes + +This format is also used for vendor-specific test actions invoked against the PPTP POTS UNI entity class when no general purpose buffer is needed. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This message format pertains to ONT-G, circuit pack and PPTP POTS UNI entity classes. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | Type 1 (Note) | +| | 15-16 | | | | | | | | | Value 1 | +| | 17 | | | | | | | | | Type 2 | +| | 18-19 | | | | | | | | | Value 2 | +| | 20 | | | | | | | | | Type 3 | +| | 21-22 | | | | | | | | | Value 3 | +| | 23 | | | | | | | | | Type 4 | +| | 24-25 | | | | | | | | | Value 4 | +| | 26 | | | | | | | | | Type 5 | +| | 27-28 | | | | | | | | | Value 5 | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|----------| +| | 29 | | | | | | | | | Type 6 | +| | 30-31 | | | | | | | | | Value 6 | +| | 32 | | | | | | | | | Type 7 | +| | 33-34 | | | | | | | | | Value 7 | +| | 35 | | | | | | | | | Type 8 | +| | 36-37 | | | | | | | | | Value 8 | +| | 38 | | | | | | | | | Type 9 | +| | 39-40 | | | | | | | | | Value 9 | +| | 41 | | | | | | | | | Type 10 | +| | 42-43 | | | | | | | | | Value 10 | +| | 44-45 | | | | | | | | | Padding | + +NOTE – Test result types are specified in clause 11.1.10. Type-value fields are packed in the lowest byte positions. Unused trailing byte positions are filled with 0 values. If more than 10 type-value pairs are to be returned, an additional test type should be defined in the test message. At the vendor's discretion, a test result may include an ordered sequence of repeated type-value pairs to represent, for example, port ordering, or first/second power input. In this case, missing values can be flagged with type = 255. + +##### Format for POTS UNI and PPTP ISDN UNI entity classes + +Byte 14 reports a summary MLT test result. The result for each test category is limited to the two values "test passed or was not executed" or "test failed". Bytes 16 and 17 report the results of a dial tone test. + +Byte 15 reports the result of a self test or a vendor-specific test that returns results in a general purpose buffer. At present, self test is not supported for the POTS UNI and PPTP ISDN UNI entity classes, and this byte should be set to 0. + +There are four possible outcomes for a given test: it can pass, fail, not be run, or not be recognized by the ONT. If an ONT does not support or recognize a given test, it is expected to deny the test request message. To avoid physical damage, an ONT may cease testing if a test – usually potentially hazardous – fails, and thus some subsequent tests will not be run. In addition, the ONT may support some but not all tests of a given suite, such as power measurements in the dial tone test sequence. The category summary in byte 14 includes two values. The value 1 indicates either that all tests in a category passed, or that nothing in the category was tested, while 0 indicates that at least one test in the category failed. Further information appears in flags specific to each test results attribute to indicate whether each detailed test was run or not, whether it passed or failed and whether a measured result is reported or not. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This message format
pertains to PPTP POTS UNI and
PPTP ISDN UNI entity classes. | +| | 12 | | | | | | | | | MS byte entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | a | b | c | d | e | f | MLT drop test result:
0 = fail test a/b/c/d/e/f
1 = pass test, or test not run
a/b/c/d/e/f:
a = hazardous potential
b = foreign EMF
c = resistive faults
d = receiver off-hook
e = ringer
f = NT 1 dc signature test | +| | 15 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | Result of self test or
vendor-specific test:
xx = 00: failed
xx = 01: passed
xx = 10: not completed | +| | 16 | | | b | b | b | d | d | d | Dial tone make-break flags:
ddd – Dial tone draw
= 000 test not run
= 01 m failed, could not draw
= 10 m slow draw
= 11 m passed
bbb – Dial tone break
= 000 test not run
= 01 m failed, could not break
= 10 m slow break
= 11 m passed
m – measured value flag
= 0 measurement not reported
= 1 measurement reported | +| | 17 | | | a | a | a | b | b | b | Dial tone power flags:
aaa – quiet channel power
bbb – dial tone power
(See Note) | +| | 18 | | | a | a | a | b | b | b | Loop test DC voltage flags
aaa – VDC, tip-ground
bbb – VDC, ring-ground
(See Note) | +| | 19 | | | a | a | a | b | b | b | Loop test AC voltage flags
aaa – VAC, tip-ground
bbb – VAC, ring-ground
(See Note) | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 20 | | | a | a | a | b | b | b | Loop test resistance flags 1
aaa – resistance, tip-ground
bbb – resistance, ring-ground
(See Note) | +| | 21 | | | a | a | a | b | b | b | Loop test resistance flags 2
aaa – resistance, tip-ring
bbb – ringer load test
(See Note) | +| | 22 | | | | | | | | | Time to draw dial tone, in 0.1 second units. Valid only if byte 16 ddd = xx1. | +| | 23 | | | | | | | | | Time to break dial tone, in 0.1 second units. Valid only if byte 16 bbb = xx1. | +| | 24 | | | | | | | | | Total dial tone power measurement, unsigned absolute value, 0.1 dB resolution, range 0 to [–] 25.5 dBm0. Values above 0 dBm0 are reported as 0. Valid only if byte 17 bbb = xx1. | +| | 25 | | | | | | | | | Quiet channel power measurement, unsigned absolute value, 1 dB resolution, range 0 to [–]90 dBm0. Valid only if byte 17 aaa = xx1. | +| | 26-27 | | | | | | | | | Tip-ground DC voltage, 2 s complement, resolution 1 V. Valid only if byte 18 aaa = xx1. | +| | 28-29 | | | | | | | | | Ring-ground DC voltage, 2 s complement, resolution 1 V. Valid only if byte 18 bbb = xx1. | +| | 30 | | | | | | | | | Tip-ground AC voltage, Vrms. Valid only if byte 19 aaa = xx1. | +| | 31 | | | | | | | | | Ring-ground AC voltage, Vrms. Valid only if byte 19 bbb = xx1. | +| | 32-33 | | | | | | | | | Tip-ground DC resistance, k $\Omega$ . Infinite resistance: 0xffff. Valid only if byte 20 aaa = xx1. | +| | 34-35 | | | | | | | | | Ring-ground DC resistance, k $\Omega$ . Infinite resistance: 0xffff. Valid only if byte 20 bbb = xx1. | +| | 36-37 | | | | | | | | | Tip-ring DC resistance, k $\Omega$ . Infinite resistance: 0xffff. Valid only if byte 21 aaa = xx1. | +| | 38 | | | | | | | | | Ringer equivalence, in 0.1 REN units. Valid only if byte 21 bbb = xx1. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------| +| | 39-40 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer. | +| | 41-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | padding | + +NOTE – Coding for 3 bit flag sets is as follows: + +- = 000 test not run; +- = 010 fail, measurement not reported; +- = 011 fail, measurement reported; +- = 110 pass, measurement not reported; +- = 111 pass, measurement reported. + +##### **Format for test action invoked against IP host config data entity class** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This format applies to entity class IP host config data. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | 0 | x | x | x | Test result:
xxx = 000: timed out, no response
xxx = 001: ICMP echo responses attached
xxx = 010: ICMP time exceeded responses attached
xxx = 011: Unexpected ICMP response
xxx = 100-111: Reserved | +| | 15 | 0 | 0 | 0 | y | y | y | y | y | yyyyy: number of meaningful bytes in the remainder of the test result message | + +If xxx = 001 (echo response – ping), the remainder of the message contains the following content. How many echo requests are sent and the resolution of the delay measurement are specific to a vendor's implementation. The special value 0xFFFF indicates a lost response. + +| | | | | | | | | | | | +|--|--------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| | 16-17 | | | | | | | | | 16-bit measurement of response delay 1, expressed in ms | +| | 18-19 | | | | | | | | | 16-bit measurement of response delay 2, expressed in ms | +| | ... | | | | | | | | | Etc. | +| | ...-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +If xxx = 010 (time exceeded – traceroute), the remainder of the message contains the following content. In PON applications, it is not expected that a route trace will exceed the available space in the message, but if it does, the more distant responses should be dropped. + +| | | | | | | | | | | | +|--|--------|---|---|---|---|---|---|---|---|----------------------------------------| +| | 16-19 | | | | | | | | | IP address of nearest neighbour | +| | 20-23 | | | | | | | | | IP address of second nearest neighbour | +| | ... | | | | | | | | | Etc. | +| | ...-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +If xxx = 011 (unexpected ICMP response), the remainder of the message contains the following content: + +| | | | | | | | | | | | +|--|-------|--|--|--|--|--|--|--|--|------------------------------------------------------------| +| | 16 | | | | | | | | | Type | +| | 17 | | | | | | | | | Code | +| | 18-19 | | | | | | | | | Checksum | +| | 20-23 | | | | | | | | | Bytes 5-8 of ICMP message (meaning depends on type/code) | +| | 24-45 | | | | | | | | | Internet header + 64 bits of original datagram (truncated) | + +##### Format for optical line supervision test action invoked against ANI-G entity class + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class.
NOTE – This message format pertains to ANI-G entity class. | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | Type = 1, power feed voltage | +| | 15-16 | | | | | | | | | V, 2s complement, 20 mV resolution | +| | 17 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | Type = 3, received optical power | +| | 18-19 | | | | | | | | | dBμW, 2s complement, 0.002 dB resolution | +| | 20 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | Type = 5, transmitted optical power, | +| | 21-22 | | | | | | | | | dBμW, 2s complement, 0.002 dB resolution | +| | 23 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | Type = 9, laser bias current | +| | 24-25 | | | | | | | | | Unsigned integer, 2 μA resolution | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|------------------------------------------| +| | 26 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | Type 12, temperature, degrees | +| | 27-28 | | | | | | | | | 2s complement, 1/256 degree C resolution | +| | 29-45 | | | | | | | | | Padding | + +NOTE – Unsupported tests are indicated with test type indicator 0 and 2 bytes of 0 data. + +#### II.2.46 Get current data + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get current data | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | | | | | | | | | MS byte attribute mask | +| | 15 | | | | | | | | | LS byte attribute mask | +| | 16-45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | + +Based on the size of the message contents field, the aggregate size of the attributes requested by a single get current data command should not exceed 25 bytes. + +#### II.2.47 Get current data response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction identifier | 6-7 | | | | | | | | | | +| Message type | 8 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get current data | +| Device identifier type | 9 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Message identifier | 10-11 | | | | | | | | | Entity class | +| | 12 | | | | | | | | | MS byte entity instance | +| | 13 | | | | | | | | | LS byte entity instance | +| Message contents | 14 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy
1001 = attribute(s) failed or unknown | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------| +| | 15 | | | | | | | | | MS byte attribute mask | +| | 16 | | | | | | | | | LS byte attribute mask | +| | 17 | | | | | | | | | Attribute value of first attribute included (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last attribute included (size depending on the type of attribute) | +| | xx-41 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Padding | +| | 42 | | | | | | | | | Optional attribute mask (attributes 1-8), used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 43 | | | | | | | | | Optional attribute mask (attributes 9-16), used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 44 | | | | | | | | | Attribute execution mask (attributes 1-8), used with 1001 encoding:
0 = default
1 = failed attribute | +| | 45 | | | | | | | | | Attribute execution mask (attributes 9-16), used with 1001 encoding:
0 = default
1 = failed attribute | + +Bytes 42 to 45 are always reserved for the optional attribute and attribute execution masks; however, the content of these bytes is only valid in conjunction with the 1001 encoding used to indicate failed or unknown attributes. + +# Appendix III + +## Traffic management options + +(This appendix does not form an integral part of this Recommendation) + +Depending on the trade-off between the complexity and the number of supported features, the ONT can have various traffic management options. Examples of traffic management implementation in the ONT are described in the following clauses. This appendix also indicates how the MIB defined in clause 9 is used for each implementation. + +It should be pointed out that the ONT traffic management is not limited to these examples. ONT traffic management is likely a place where every vendor searches for a proprietary feature to give it a competitive advantage. However, every proprietary feature requires some kind of management that impacts the OMCI. In fact, it is difficult for the specification given in this Recommendation to keep up with the technological and feature innovations. It is envisioned that vendor specific managed entities will be needed to manage the traffic management related functions in the ONT. + +## III.1 Priority queue configuration + +When the focus is on low complexity implementation, the ONT uses the priority controlled upstream traffic method. In this case, the ONT has no traffic contract or QoS awareness. The ONT is configured by the OLT with a priority for each connection for both directions. + +Theoretically, UPC is needed at every multiplexing point, including the ONT. A system with the UPC function has to monitor the traffic volume entering the network from all active connections to ensure that the agreed parameters are not violated and to deploy a frame discard or tag policy. In the priority queue implementation, the UPC function is moved to the OLT, where it protects the core network. The PON is protected by the "UPC-like" MAC (via the DBA process). The MAC manages all connections from an T-CONT as a whole. Essentially, the MAC isolates T-CONTs from each other. + +As such, CPEs sharing one T-CONT may have to regulate their own connection streams to maintain quality. A CPE sending out more traffic on one connection will do so at the expense of the other connections established at the same T-CONT. + +## III.2 Explicit traffic scheduler configuration + +In slightly more complex implementations, ONTs may implement some level of traffic scheduling within each T-CONT. These are described using priority queues and one or more levels of traffic scheduler MEs. The arrangement of priority queues and traffic schedulers is determined by the ONT, and is generally not controllable by the OLT. An example of the configuration of the traffic scheduler can be as proposed in Figure III.2-1. This model consists of three stages, such as two delay control and one guaranteed rate control stages. A delay control stage can be worked by HOL (head of line) scheduling. A guaranteed rate control stage can be worked by WRR. + +![Architectural model in ONT diagram showing three stages of traffic control: Stage 3 Delay control (HOL), Stage 2 Guaranteed rate control (WRR), and Stage 1 Delay control (HOL), leading to a T-CONT Buffer. Inputs are priority queues #1 through #32.](ca29ffd592187cc2b1719b98a5417521_img.jpg) + +The diagram illustrates the architectural model in an ONT. On the left, 32 priority queues are shown, labeled #1, #2, #3, ..., #i, ..., #32. These queues feed into three sequential stages of traffic control, each represented by a vertical rectangular block. + +Stage 3 (leftmost) is labeled 'Delay control (HOL)' and contains circles representing head-of-line (HOL) delays. + +Stage 2 (middle) is labeled 'Guaranteed rate control (WRR)' and also contains circles. + +Stage 1 (rightmost) is labeled 'Delay control (HOL)' and contains circles. + +Arrows indicate the flow of traffic from left to right through these stages. + +A 'Traffic Scheduler' is shown at the bottom, with lines connecting it to the HOL circles in each of the three stages. + +The output of Stage 1 flows into a 'T-CONT Buffer', represented by a cylinder on the far right. + +Architectural model in ONT diagram showing three stages of traffic control: Stage 3 Delay control (HOL), Stage 2 Guaranteed rate control (WRR), and Stage 1 Delay control (HOL), leading to a T-CONT Buffer. Inputs are priority queues #1 through #32. + +**Figure III.2-1 – Architectural model in ONT** + +## III.3 Traffic descriptor configuration + +An alternative method of controlling traffic in ONTs is to provide traffic descriptors to the ONT, and leave the details of honouring and enforcing these contracts to the ONT implementation. This is controlled using the GEM traffic descriptor MEs. This method uses the theoretical assumption that a work-conserving scheduling methodology will be used. + +# Appendix IV + +## Video return path + +(This appendix does not form an integral part of this Recommendation) + +## IV.1 Network overview + +This Recommendation considers networks that use G-PON systems that include a video overlay. This system provides a bidirectional GEM transport service and a unidirectional video or data downstream broadcast or unicast service. If only broadcast video services are desired, then the only video transport required is the third wavelength, as shown in Figure IV.1-1. The ONT converts the signals on the third wavelength to electrical signals on a coaxial output, suitable for video appliances such as televisions. + +![Figure IV.1-1: A G-PON with broadcast video only. The diagram shows a Video Tx connected to an OLT. The OLT is connected to a cloud representing the network. The OLT is also connected to an ONU via a split. The ONU is connected to a TV via a split.](bc8039d3abc96b2bb00bd6dd54776fdc_img.jpg) + +The diagram shows a block labeled 'Video Tx' with an arrow pointing to a line connecting an orange cloud (representing the network) to a block labeled 'OLT'. From the 'OLT', a line goes to a 1:N splitter (represented by diverging orange lines), which then connects to a block labeled 'ONU'. From the 'ONU', a line goes to another splitter (represented by diverging black lines) which connects to a block labeled 'TV'. + +Figure IV.1-1: A G-PON with broadcast video only. The diagram shows a Video Tx connected to an OLT. The OLT is connected to a cloud representing the network. The OLT is also connected to an ONU via a split. The ONU is connected to a TV via a split. + +**Figure IV.1-1 – A G-PON with broadcast video only** + +In many cases, however, interactive video services are needed. In this case, the customer's video termination equipment (commonly referred to as a set-top box, or STB) needs connectivity back to the video control equipment in the central office. In the case of the G-PON system, this connectivity must be provided by the ONT and OLT. This scenario is depicted in Figure IV.1-2. The connection begins in the STB, which transmits its information up the coaxial cables that connect it to the ONT. The ONT must receive this information, and adapt it to be carried on the G-PON in the form of an GEM connection. The OLT terminates the GEM connection, and recovers the VRP upstream datagrams. These datagrams are then interworked at some level (possibly ATM cross-connection, AAL5 interworking, or application-specific interworking). At some point, the resulting data terminates on the video control equipment. + +![Figure IV.1-2: A G-PON with interactive video services. The diagram shows a Video Tx connected to an OLT. The OLT is connected to a cloud representing the network. The OLT is also connected to an ONU via a split. The ONU is connected to a STB via a split. The ONU is also connected to a VRP block. The VRP block is connected to a Video control block via an ATM cloud. The VRP block is also connected to the STB via a split. Labels indicate the ONU-Network interface and the STB-ONU interface.](36646be0830c36731998b1672a363778_img.jpg) + +This diagram expands on the previous one. It includes a 'Video Tx' block and a 'Video control' block. The 'Video control' block is connected to an orange cloud labeled 'ATM'. A dashed purple line connects the 'ATM' cloud through the 'OLT' to the 'ONU' block, which now contains two sub-blocks: 'ONU' and 'VRP'. The 'OLT' is connected to the 'ONU' via an orange splitter. A label 'ONU-Network interface' points to the connection between the splitter and the ONU. The 'ONU/VRP' block is connected to an 'STB' block via a black splitter. A label 'STB-ONU interface' points to this connection. A dashed purple line also connects the 'VRP' sub-block to the 'STB'. In the bottom right, there is a reference code: G.984.4(08)\_FIV.1-2. + +Figure IV.1-2: A G-PON with interactive video services. The diagram shows a Video Tx connected to an OLT. The OLT is connected to a cloud representing the network. The OLT is also connected to an ONU via a split. The ONU is connected to a STB via a split. The ONU is also connected to a VRP block. The VRP block is connected to a Video control block via an ATM cloud. The VRP block is also connected to the STB via a split. Labels indicate the ONU-Network interface and the STB-ONU interface. + +**Figure IV.1-2 – A G-PON with interactive video services** + +Figure IV.1-2 defines two interfaces that are important to interoperability. The STB-ONT interface is the first. This interface is defined by two standards: [SCTE 55-1] and [SCTE 55-2]. These are peer standards that are mutually exclusive; that is, a system will run either one or the other, but not both at one time. Furthermore, each of these standards defines several grades of capability, one being chosen as the default (or basic practice). Clauses IV.2 and IV.4 clarify this interface for the purposes of providing the video return path over G-PON. + +The second important interface is the ONT-network interface. This logical interface is a GEM connection that conducts the return path information back to the video equipment in the central office. The information must be formatted in a standardized way so that common control equipment can be used. The formatting depends on the particular return path interface being used. Clauses IV.3 and IV.5 define these formats. + +Given the situation that there are two modes on both interfaces, it makes sense that the ONT has two modes of operation, denoted mode 1 and mode 2. Mode 1 corresponds to support of the SCTE 55-1 system, and mode 2 corresponds to support of the SCTE 55-2 systems. The mode is set by the network operator during the initialization management of the video service. + +## **IV.2 Mode 1 STB-ONT interface** + +The STB-ONT interface, in this case, is based on that from the commonly deployed [SCTE 55-1]. [SCTE 55-1] defines all the aspects of the interactive video control system, while the STB-ONT interface herein described is only concerned with the upstream transmission of data. Therefore, we specify below which clauses are relevant to the definition of the STB-ONT interface. + +Relevant clauses of [SCTE 55-1] that apply to the STB-ONT interface: + +- 5.2 Physical layer for return-path transmission +- 5.2.1 Return-path modem description – A general explanation, required. +- 5.2.2 RF return path packet format – Specifies the format of the upstream packet, required. + +Please note that the unique word specified in this clause is given in standard QPSK notation, and not differential QPSK notation. + +- 5.2.3 RF return-path forward error correction – Specifies the code used for the FEC bytes, optional. + +Please note that while the FEC will be calculated by compliant STBs, the ONT's processing of the FEC is optional. + +- 5.2.4 RF return-path randomizer – Specifies the randomizer used in the upstream packets, required. + +Please note that the randomizer output is applied to the entire packet EXCEPT the unique word. Also, the programmable value of the randomizer seed to be used is given in the video return path service profile managed entity. + +- 5.2.5 RF return path modulator – Specifies the physical layer to be used, required. + +Note that while the centre frequency is specified to a wider range, in actual practice this frequency is limited from 8 to 12 MHz. Also, the DQPSK mode to be used is given in the video return path service profile managed entity. + +- 5.2.6 RF return-path demodulator specification – Specifies the physical layer to be used, required. + +All other clauses of [SCTE 55-1] are not relevant to the STB-ONT interface. In particular, the extended practice (clause 5.3) is explicitly not supported. + +## IV.3 Mode 1 ONT-network interface + +In mode 1, the ONT must forward the derandomized packet sequence field (1 byte) and the ATM data (53 bytes) intact to the video control system. The procedure to do this is: + +- 1) Receive the DQPSK burst, and capture all 62 bytes of data and measure the power level of the burst relative to the nominal input power level for the receiver. +- 2) Exclusive OR the randomizer sequence with the received data. +- 3) Calculate the FEC parity, compare with that received, and detect/correct errors. Discard cells that have uncorrectable errors (optional). +- 4) Assemble the datagram to be forwarded, which is 56 bytes in length. +- 5) Encapsulate the datagram using GEM. +- 6) Forward the GEM fragment over a GEM port CTP allocated on the PON. + +The structure of the incoming RF burst data and the outgoing GEM circuit data is shown in Figure IV.3-1. The outgoing datagram is always 56 bytes in length, and is composed of a two-byte level indication field, a one-byte packet sequence field, and a 53-byte ATM data field. The unique word and FEC bytes are terminated in the ONT. The resulting GEM fragment is 61 bytes (488 bits). + +![Figure IV.3-1: The transformation of a 55-1 formatted burst into a GEM fragment. The diagram shows three stages of data structure. The top stage is the incoming RF burst: Unique Word (3.5 B), Video Cell-Header (6 B), Payload Data (48 B), and FEC-Parity (8 B). A 'Randomizer XOR (and optional FEC correction)' process is applied to the middle two fields. The middle stage shows the resulting datagram: Level Ind (2 B), Video Cell-Header (6 B), and Payload Data (48 B). The bottom stage shows the final GEM fragment: GEM Header (5 B) followed by GEM Payload (56 B), which contains the Level Ind, Video Cell-Header, and Payload Data from the previous stage.](58dc37807456010bbb82f01f44def458_img.jpg) + +| | | | | +|----------------------------------------------|----------------------------|------------------------|---------------------| +| Unique Word
(3.5 B) | Video Cell-Header
(6 B) | Payload Data
(48 B) | FEC-Parity
(8 B) | +| Randomizer XOR (and optional FEC correction) | | | | +| Level Ind
(2 B) | Video Cell-Header
(6 B) | Payload Data
(48 B) | | +| GEM Header
(5 B) | GEM Payload
(56 B) | | | + +Figure IV.3-1: The transformation of a 55-1 formatted burst into a GEM fragment. The diagram shows three stages of data structure. The top stage is the incoming RF burst: Unique Word (3.5 B), Video Cell-Header (6 B), Payload Data (48 B), and FEC-Parity (8 B). A 'Randomizer XOR (and optional FEC correction)' process is applied to the middle two fields. The middle stage shows the resulting datagram: Level Ind (2 B), Video Cell-Header (6 B), and Payload Data (48 B). The bottom stage shows the final GEM fragment: GEM Header (5 B) followed by GEM Payload (56 B), which contains the Level Ind, Video Cell-Header, and Payload Data from the previous stage. + +Figure IV.3-1– The transformation of a 55-1 formatted burst into a GEM fragment + +The level indication field is formatted as: a1bb bbbb 0000 0000, where: + +Bit a is a detection indicator to be used if FEC is implemented in the ONT (if not, bit a should be set to zero), where: + +a = 0 means burst was detected without errors; + +a = 1 means a burst was detected with errors, but was corrected. + +The 1 is a reserved bit. + +Bits bbbbb are a power indication, containing the 2s complement representation of the measured power of this burst, in units of decibels relative to the nominal receive power of the equipment. For example, if the nominal receive power of the ONT is 10 dBmV, and a burst arrives with 17 dBmV, then bbbbb = 000111. If the same ONT receives a 7 dBmV burst, then bbbbb = 111101. + +The "0000 0000" are all reserved bits. + +The GEM port-ID that carries the video return path data can be configured to provide a non-assured traffic service. The data rate of the service can be calculated from the latency requirements of the 55-1 protocol and equipment implementation. Practical implementations of this protocol have round trip delay tolerances on the order of 100 ms. After this time, the STB will begin to re-transmit its upstream bursts. One of the contributors of the delay will be the cell transmission time, which in our case is the inverse of the data burst rate. + +For example, if 20 ms is allocated for cell transmission time, then the cell rate for the video return path connection should be made $488/20\text{ms} \sim 25\text{ kbit/s}$ . + +To summarize, the ONT-network interface is 56-byte payloads (as defined above) encapsulated in GEM, carried in a GEM port-ID. + +## IV.4 Mode 2 STB-ONT interface + +The STB-ONT interface in this case is based on that from the commonly deployed [SCTE 55-2]. [SCTE 55-2] defines all the aspects of the interactive video control system, while the STB-ONT interface herein described is only concerned with the upstream transmission of data. Therefore, we specify below which clauses are relevant to the definition of the STB-ONT interface. + +Relevant clauses of [SCTE 55-2] that apply to the STB-ONT interface: + +- 2.2 Upstream physical interface specification – A general explanation of the system, required. +- 2.2.1 Quaternary phase shift keying (QPSK) – A description of the physical layer used, required. + - Grade A 256 kbit/s is optional. + - Grade B 1.544 Mbit/s is required. + - Grade C 3.088 Mbit/s is optional. +- 2.2.2 Coaxial cable impedance – A physical layer parameter, required. +- 2.2.3 Time division multiple access (TDMA), optional. +- 2.2.4 Contention-based access, required. + +All other clauses of [SCTE 55-2] are not relevant to the STB-ONT interface. + +## IV.5 Mode 2 ONT-network interface + +In mode 2, the ONT forwards the de-randomized ATM cells (53 bytes) to the video control system. The procedure to do this is: + +- 1) Receive the QPSK burst, and capture all 59 bytes of data. +- 2) Exclusive OR the randomizer sequence with the received data. +- 3) Calculate the FEC parity, compare with that received, and detect/correct errors. Discard cells that have uncorrectable errors (required). +- 4) Forward the ATM cells over a GEM port-ID allocated on the PON. + +The structure of the incoming RF burst data and the outgoing GEM data is shown in Figure IV.5-1. The outgoing datagram is a 53-byte ATM cell. The unique word and FEC bytes are terminated in the ONT. The resulting GEM fragment is 58 bytes (464 bits). + +![Diagram showing the transformation of a 55-2 formatted burst into a GEM fragment. The top row shows a burst with four fields: Unique Word (4 B), Video Cell-Header (5 B), Payload Data (48 B), and FEC-Parity (6 B). A 'Randomizer XOR (and optional FEC correction)' is applied to the Video Cell-Header and Payload Data. The middle row shows the result: Video Cell-Header (5 B) and Payload Data (48 B). The bottom row shows the final GEM fragment with a GEM Header (5 B) and GEM Payload (53 B).](926c64a6177547a91f650c4c6f85ecb2_img.jpg) + +The diagram illustrates the transformation of a 55-2 formatted burst into a GEM fragment. It consists of three horizontal rows of data blocks. + +- Top Row (Burst):** A yellow block labeled "Unique Word (4 B)", a blue block labeled "Video Cell-Header (5 B)", a green block labeled "Payload Data (48 B)", and a pink block labeled "FEC-Parity (6 B)". +- Middle Row (Intermediate):** A blue block labeled "Video Cell-Header (5 B)" and a green hatched block labeled "Payload Data (48 B)". +- Bottom Row (GEM Fragment):** A pink block labeled "GEM Header (5 B)" and a white block labeled "GEM Payload (53 B)". + +Between the top and middle rows, a label "Randomizer XOR (and optional FEC correction)" is centered, with lines connecting it to the Video Cell-Header and Payload Data blocks in both rows. Lines also connect the Video Cell-Header and Payload Data blocks from the top row to the middle row, and from the middle row to the bottom row. + +Diagram showing the transformation of a 55-2 formatted burst into a GEM fragment. The top row shows a burst with four fields: Unique Word (4 B), Video Cell-Header (5 B), Payload Data (48 B), and FEC-Parity (6 B). A 'Randomizer XOR (and optional FEC correction)' is applied to the Video Cell-Header and Payload Data. The middle row shows the result: Video Cell-Header (5 B) and Payload Data (48 B). The bottom row shows the final GEM fragment with a GEM Header (5 B) and GEM Payload (53 B). + +**Figure IV.5-1 – The transformation of a 55-2 formatted burst into a GEM fragment** + +The GEM port-ID that carries the video return path data can be configured to support the operator-chosen QoS. + +To summarize, the ONT-network interface is 53-byte payloads (as defined above) encapsulated in GEM, carried in a GEM port-ID. + +# Index + +| ME name | Clause | Class | +|------------------------------------------------------------|---------|-------| +| 802.11 general purpose object | 9.6.4 | 94 | +| 802.11 MAC and PHY operation and antenna data | 9.6.5 | 95 | +| 802.11 performance monitoring history data | 9.6.7 | 96 | +| 802.11 PHY FHSS DSSS IR tables | 9.6.6 | 97 | +| 802.11 station management data 1 | 9.6.2 | 92 | +| 802.11 station management data 2 | 9.6.3 | 93 | +| 802.1p mapper service profile | 9.3.10 | 130 | +| AAL 5 performance monitoring history data | 9.13.6 | 18 | +| AAL 5 profile | 9.13.5 | 16 | +| ANI-G | 9.2.1 | 263 | +| ARP configuration data | 9.4.11 | 77 | +| ARP service profile | 9.4.10 | 76 | +| Attribute | 9.12.10 | 289 | +| Authentication security method | 9.12.4 | 148 | +| Call control performance monitoring history data | 9.9.12 | 140 | +| Cardholder | 9.1.5 | 5 | +| CES physical interface performance monitoring history data | 9.8.4 | 23 | +| CES service profile-G | 9.8.3 | 21 | +| Circuit pack | 9.1.6 | 6 | +| Dot1 rate limiter | 9.3.18 | 298 | +| Dot1ag CFM stack | 9.3.25 | 305 | +| Dot1ag chassis-management info | 9.3.26 | 306 | +| Dot1ag default MD level | 9.3.21 | 301 | +| Dot1ag maintenance association | 9.3.20 | 300 | +| Dot1ag maintenance domain | 9.3.19 | 299 | +| Dot1ag MEP | 9.3.22 | 302 | +| Dot1ag MEP CCM database | 9.3.24 | 304 | +| Dot1ag MEP status | 9.3.23 | 303 | +| Dot1X configuration profile | 9.3.15 | 291 | +| Dot1X performance monitoring history data | 9.3.16 | 292 | +| Dot1X port extension package | 9.3.14 | 290 | +| Equipment extension package | 9.1.9 | 160 | +| Equipment protection profile | 9.1.11 | 159 | +| Ethernet flow termination point | 9.8.9 | 286 | +| Ethernet performance monitoring history data | 9.5.2 | 24 | +| Ethernet performance monitoring history data 2 | 9.5.3 | 89 | +| Ethernet performance monitoring history data 3 | 9.5.4 | 296 | +| Extended VLAN tagging operation configuration data | 9.3.13 | 171 | +| FEC performance monitoring history data | 9.2.11 | 312 | + +| ME name | Clause | Class | +|-------------------------------------------------------------|---------------|--------------| +| GAL Ethernet performance monitoring history data | 9.2.8 | 276 | +| GAL Ethernet profile | 9.2.7 | 272 | +| GAL TDM performance monitoring history data | 9.2.10 | 275 | +| GAL TDM profile | 9.2.9 | 271 | +| GEM interworking termination point | 9.2.4 | 266 | +| GEM port network CTP | 9.2.3 | 268 | +| GEM port performance monitoring history data | 9.2.6 | 267 | +| GEM traffic descriptor | 9.11.3 | 280 | +| General purpose buffer | 9.12.12 | 308 | +| ICMP performance monitoring history data 1 | 9.4.8 | 72 | +| ICMP performance monitoring history data 2 | 9.4.9 | 73 | +| Interworking VCC termination point | 9.13.4 | 14 | +| IP host config data | 9.4.12 | 134 | +| IP host performance monitoring history data | 9.4.13 | 135 | +| IP port configuration data | 9.4.3 | 67 | +| IP route table | 9.4.4 | 74 | +| IP router configuration data | 9.4.2 | 69 | +| IP router performance monitoring history data 1 | 9.4.6 | 70 | +| IP router performance monitoring history data 2 | 9.4.7 | 71 | +| IP router service profile | 9.4.1 | 68 | +| IP static routes | 9.4.5 | 75 | +| Large string | 9.12.5 | 157 | +| Logical N x 64 kbit/s sub-port connection termination point | 9.8.2 | 13 | +| MAC bridge configuration data | 9.3.2 | 46 | +| MAC bridge performance monitoring history data | 9.3.3 | 51 | +| MAC bridge port bridge table data | 9.3.8 | 50 | +| MAC bridge port configuration data | 9.3.4 | 47 | +| MAC bridge port designation data | 9.3.5 | 48 | +| MAC bridge port filter preassign table | 9.3.7 | 79 | +| MAC bridge port filter table data | 9.3.6 | 49 | +| MAC bridge port performance monitoring history data | 9.3.9 | 52 | +| MAC bridge service profile | 9.3.1 | 45 | +| Managed entity | 9.12.9 | 288 | +| MGC config data | 9.9.16 | 155 | +| MGC config portal | 9.9.20 | 154 | +| MGC performance monitoring history data | 9.9.17 | 156 | +| MoCA Ethernet performance monitoring history data | 9.10.2 | 163 | +| MoCA interface performance monitoring history data | 9.10.3 | 164 | +| Multicast GEM interworking termination point | 9.2.5 | 281 | +| Multicast operations profile | 9.3.27 | 309 | + +| ME name | Clause | Class | +|---------------------------------------------------------|---------------|--------------| +| Multicast subscriber config info | 9.3.28 | 310 | +| Multicast subscriber monitor | 9.3.29 | 311 | +| Network address | 9.12.3 | 137 | +| Network dial plan table | 9.9.10 | 145 | +| Octet string | 9.12.11 | 307 | +| OLT-G | 9.12.2 | 131 | +| OMCI | 9.12.8 | 287 | +| ONT data | 9.1.3 | 2 | +| ONT power shedding | 9.1.7 | 133 | +| ONT remote debug | 9.1.12 | 158 | +| ONT2-G | 9.1.2 | 257 | +| ONT-G | 9.1.1 | 256 | +| Physical path termination point 802.11 UNI | 9.6.1 | 91 | +| Physical path termination point CES UNI | 9.8.1 | 12 | +| Physical path termination point Ethernet UNI | 9.5.1 | 11 | +| Physical path termination point ISDN UNI | 9.9.21 | 80 | +| Physical path termination point LCT UNI | 9.13.3 | 83 | +| Physical path termination point MoCA UNI | 9.10.1 | 162 | +| Physical path termination point POTS UNI | 9.9.1 | 53 | +| Physical path termination point video ANI | 9.13.2 | 90 | +| Physical path termination point video UNI | 9.13.1 | 82 | +| Physical path termination point xDSL UNI part 1 | 9.7.1 | 98 | +| Physical path termination point xDSL UNI part 2 | 9.7.2 | 99 | +| Port mapping package-G | 9.1.8 | 297 | +| Priority queue-G | 9.11.1 | 277 | +| Protection data | 9.1.10 | 279 | +| Pseudowire maintenance profile | 9.8.7 | 284 | +| Pseudowire performance monitoring history data | 9.8.8 | 285 | +| Pseudowire termination point | 9.8.5 | 282 | +| Radius performance monitoring history data | 9.3.17 | 293 | +| RTP performance monitoring history data | 9.9.13 | 144 | +| RTP profile data | 9.9.7 | 143 | +| RTP pseudowire parameters | 9.8.6 | 283 | +| SIP agent config data | 9.9.3 | 150 | +| SIP agent performance monitoring history data | 9.9.14 | 151 | +| SIP call initiation performance monitoring history data | 9.9.15 | 152 | +| SIP config portal | 9.9.19 | 149 | +| SIP user data | 9.9.2 | 153 | +| Software image | 9.1.4 | 7 | +| TC adaptor performance monitoring history data xDSL | 9.7.25 | 116 | + +| ME name | Clause | Class | +|--------------------------------------------------------|---------------|--------------| +| T-CONT | 9.2.2 | 262 | +| TCP/UDP config data | 9.4.14 | 136 | +| Threshold data 1 | 9.12.6 | 273 | +| Threshold data 2 | 9.12.7 | 274 | +| Traffic scheduler-G | 9.11.2 | 278 | +| TU CTP | 9.8.10 | 294 | +| TU performance monitoring history data | 9.8.11 | 295 | +| UNI-G | 9.12.1 | 264 | +| VDSL2 line configuration extensions | 9.7.6 | 165 | +| VDSL2 line inventory and status data part 1 | 9.7.16 | 168 | +| VDSL2 line inventory and status data part 2 | 9.7.17 | 169 | +| VDSL2 line inventory and status data part 3 | 9.7.18 | 170 | +| Video return path performance monitoring history data | 9.13.8 | 129 | +| Video return path service profile | 9.13.7 | 128 | +| VLAN tagging filter data | 9.3.11 | 84 | +| VLAN tagging operation configuration data | 9.3.12 | 78 | +| Voice service profile | 9.9.6 | 58 | +| VoIP application service profile | 9.9.8 | 146 | +| VoIP config data | 9.9.18 | 138 | +| VoIP feature access codes | 9.9.9 | 147 | +| VoIP line status | 9.9.11 | 141 | +| VoIP media profile | 9.9.5 | 142 | +| VoIP voice CTP | 9.9.4 | 139 | +| VP network CTP-G | 9.13.9 | 269 | +| VP performance monitoring history data | 9.13.10 | 62 | +| xDSL channel configuration profile | 9.7.7 | 107 | +| xDSL channel downstream status data | 9.7.19 | 102 | +| xDSL channel upstream status data | 9.7.20 | 103 | +| xDSL downstream RFI bands profile | 9.7.11 | 111 | +| xDSL line configuration profile part 1 | 9.7.3 | 104 | +| xDSL line configuration profile part 2 | 9.7.4 | 105 | +| xDSL line configuration profile part 3 | 9.7.5 | 106 | +| xDSL line inventory and status data part 1 | 9.7.12 | 100 | +| xDSL line inventory and status data part 2 | 9.7.13 | 101 | +| xDSL line inventory and status data part 3 | 9.7.14 | 166 | +| xDSL line inventory and status data part 4 | 9.7.15 | 167 | +| xDSL PSD mask profile | 9.7.10 | 110 | +| xDSL subcarrier masking downstream profile | 9.7.8 | 108 | +| xDSL subcarrier masking upstream profile | 9.7.9 | 109 | +| xDSL xTU-C channel performance monitoring history data | 9.7.23 | 114 | + +| ME name | Clause | Class | +|--------------------------------------------------------|---------------|--------------| +| xDSL xTU-C performance monitoring history data | 9.7.21 | 112 | +| xDSL xTU-R channel performance monitoring history data | 9.7.24 | 115 | +| xDSL xTU-R performance monitoring history data | 9.7.22 | 113 | + +# Bibliography + +- [b-ITU-T G.984.1] Recommendation ITU-T G.984.1 (2008), *Gigabit-capable passive optical networks (GPON): General characteristics.* +- [b-ITU-T G.992.2] Recommendation ITU-T G.992.2 (1999), *Splitterless asymmetric digital subscriber line (ADSL) transceivers.* +- [b-ITU-T X.690] Recommendation ITU-T X.690 (2008) | ISO/IEC 8825-1:2008, *Information technology – ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER).* +- [b-ITU-T Y.1731] Recommendation ITU-T Y.1731 (2008), *OAM functions and mechanisms for Ethernet based networks.* +- [b-ATIS T1.403] ATIS T1.403 (2007), *Network to Customer Installation Interfaces - DS1 Electrical Interface.* +<[http://webstore.ansi.org/RecordDetail.aspx?sku=T1.403-1999\(R2007\)](http://webstore.ansi.org/RecordDetail.aspx?sku=T1.403-1999(R2007))> +- [b-IEEE 802.1AB] IEEE 802.1AB-2005, *IEEE Standard for local and metropolitan area networks – Station and Media Access Control Connectivity Discovery.* +<> +- [b-IEEE 802.1ag] IEEE 802.1ag-2007, *IEEE Standard for local and metropolitan area networks – Virtual Bridged Local Area Networks Amendment 5: Connectivity Fault Management.* +<> +- [b-IEEE 802.1X] IEEE 802.1X-2004, *IEEE Standard for local and metropolitan area networks – Port-Based Network Access Control.* +<> +- [b-IEEE 802.3] IEEE 802.3-2005, *IEEE Standard for local and metropolitan area networks – Specific requirements – Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications.* +<> +- [b-IETF RFC 1213] IETF RFC 1213 (1991), *Management Information Base for Network Management of TCP/IP-based internets: MIB-II.* +<> +- [b-IETF RFC 1700] IETF RFC 1700 (1994), *Assigned Numbers.* +<> +- [b-IETF RFC 2236] IETF RFC 2236 (1997), *Internet Group Management Protocol, Version 2.* +<> +- [b-IETF RFC 2464] IETF RFC 2464 (1998), *Transmission of IPv6 Packets over Ethernet Networks.* +<> +- [b-IETF RFC 2516] IETF RFC 2516 (1999), *A Method for Transmitting PPP over Ethernet (PPPoE).* +<> +- [b-IETF RFC 2579] IETF RFC 2579 (1999), *Textual Conventions for SMIv2.* +<> + +- [b-IETF RFC 2685] IETF RFC 2685 (1999), *Virtual Private Networks Identifier*. + <> +- [b-IETF RFC 2737] IETF RFC 2737 (1999), *Entity MIB (Version 2)*. + <> +- [b-IETF RFC 2819] IETF RFC 2819 (2000), *Remote Network Monitoring Management Information Base*. + <> +- [b-IETF RFC 2863] IETF RFC 2863 (2000), *The Interfaces Group MIB*. + <> +- [b-IETF RFC 2933] IETF RFC 2933 (2000), *Internet Group Management Protocol MIB*. + <> +- [b-IETF RFC 3261] IETF RFC 3261 (2002), *SIP: Session Initiation Protocol*. + <> +- [b-IETF RFC 3376] IETF RFC 3376 (2002), *Internet Group Management Protocol, Version 3*. + <> +- [b-IETF RFC 3417] IETF RFC 3417 (2002), *Transport Mappings for the Simple Network Management Protocol (SNMP)*. + <> +- [b-IETF RFC 3810] IETF RFC 3810 (2004), *Multicast Listener Discovery Version 2 (MLDv2) for IPv6*. + <> +- [b-IETF RFC 4541] IETF RFC 4541 (2006), *Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches*. + <> +- [b-IETF RFC 4789] IETF RFC 4789 (2006), *Simple Network Management Protocol (SNMP) over IEEE 802 Networks*. + <> + + + + + +# **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| 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a/marked/G/T-REC-G.987.1-201603-I_PDF-E/raw.md b/marked/G/T-REC-G.987.1-201603-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..6ee480399ec9ebb24e4e43a31e27c1538974a8c2 --- /dev/null +++ b/marked/G/T-REC-G.987.1-201603-I_PDF-E/raw.md @@ -0,0 +1,1440 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.987.1** + +(03/2016) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical line +systems for local and access networks + +--- + +**10-Gigabit-capable passive optical networks +(XG-PON): General requirements** + +Recommendation ITU-T G.987.1 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.987.1 + +## 10-Gigabit-capable passive optical networks (XG-PON): General requirements + +## Summary + +Recommendation ITU-T G.987.1 addresses the general requirements of 10 Gigabit-capable passive optical network (XG-PON) systems, in order to guide and motivate the physical layer and the transmission convergence layer specifications. The general requirements include examples of services, user network interfaces (UNIs) and service node interfaces (SNIs), as well as the principal deployment configurations that are requested by network operators. This Recommendation also includes the system and operational requirements to meet the needs of supporting various business and residential applications. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.987.1 | 2010-01-13 | 15 | 11.1002/1000/10410 | +| 1.1 | ITU-T G.987.1 (2010) Amd. 1 | 2012-04-22 | 15 | 11.1002/1000/11498 | +| 2.0 | ITU-T G.987.1 | 2016-03-29 | 15 | 11.1002/1000/12794 | + +## Keywords + +Asymmetric XG-PON (X=10 Gbit/s), general requirements, TDMA. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2016 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 3 | +| 3.1 Terms defined elsewhere ..... | 3 | +| 3.2 Terms defined in this Recommendation..... | 3 | +| 4 Abbreviations and acronyms ..... | 3 | +| 5 Architecture of the optical access network ..... | 3 | +| 5.1 Network architecture ..... | 3 | +| 5.2 Reference configuration ..... | 6 | +| 6 Migration scenarios ..... | 12 | +| 6.1 Migration from legacy PON to XG-PON..... | 13 | +| 6.2 Migration from XG-PON1 to XG-PON2 ..... | 14 | +| 6.3 Overlay of XG-PON or hybrid XG-PON..... | 14 | +| 6.4 RE architecture options ..... | 14 | +| 7 Service requirements ..... | 15 | +| 7.1 Services..... | 15 | +| 7.2 Maximum/mean signal transfer delay tolerance..... | 16 | +| 7.3 Maximum Ethernet packet size ..... | 16 | +| 7.4 Synchronization features and quality ..... | 17 | +| 7.5 Leased line T1/E1 emulation..... | 17 | +| 7.6 QoS and traffic management ..... | 17 | +| 8 Physical layer requirements..... | 18 | +| 8.1 Fibre characteristics..... | 18 | +| 8.2 Optical wavelengths of XG-PON ..... | 18 | +| 8.3 Bit rates..... | 18 | +| 8.4 Optical power budget ..... | 19 | +| 8.5 Split ratio ..... | 19 | +| 8.6 Fibre distance..... | 20 | +| 9 System level requirements..... | 20 | +| 9.1 Power saving and energy efficiency ..... | 20 | +| 9.2 Authentication/identification/encryption..... | 21 | +| 9.3 Dynamic bandwidth assignment (DBA) ..... | 21 | +| 9.4 Eye safety ..... | 22 | +| 10 Operational requirements..... | 22 | +| 10.1 ONU management ..... | 22 | +| 10.2 PON supervision..... | 22 | +| 11 Resilience and protection on ODN ..... | 23 | + +| | Page | +|--------------------------------------------------------------------------------------------------------|-------------| +| Appendix I – Examples of practical XG-PON system architecture..... | 24 | +| I.1    Services, UNIs and SNIs ..... | 24 | +| I.2    Typical system architectures ..... | 25 | +| I.3    Service protocol stacks ..... | 27 | +| Appendix II – Synchronizing requirements for wireless in CBU scenario..... | 38 | +| Appendix III – External access network back-up ..... | 39 | +| Appendix IV – Operation with IEEE 1588: Principles..... | 42 | +| Appendix V – Operation with IEEE 1588: Use cases for frequency and time of day
synchronization..... | 43 | +| Appendix VI – Operation with IEEE 1588 ..... | 48 | +| Bibliography..... | 49 | + +## Recommendation ITU-T G.987.1 + +## 10-Gigabit-capable passive optical networks (XG-PON): General requirements + +# 1 Scope + +This Recommendation addresses the general requirements of 10-Gigabit-capable passive optical networks (XG-PON) systems, in order to guide and motivate the physical layer and the transmission convergence layer specifications. The general requirements include examples of services, user network interfaces (UNIs) and service node interfaces (SNIs), as well as the principal deployment configurations that are requested by network operators. This Recommendation also includes the system and operational requirements to meet the needs of supporting various business and residential applications. + +As much as possible, this Recommendation maintains characteristics from [ITU-T G.982], and the ITU-T G.983.x, and ITU-T G.984.x series of Recommendations. This is to promote backward compatibility with existing optical distribution networks (ODNs) that comply with those Recommendations. Furthermore, this Recommendation provides a mechanism that enables seamless subscriber migration from Gigabit PON (generic term to represent both G-PON and GE-PON) to XG-PON using the wavelength division multiplexing (WDM) defined in the ITU-T G.984.x series of Recommendations. + +There are two types of XG-PONs based on the upstream line rate: XG-PON1, featuring a 2.5 Gbit/s upstream path, and XG-PON2, featuring a 10 Gbit/s one, XG-PON2 being symmetrical it can be referred to as XGS-PON. The initial phase of this Recommendation only addresses XG-PON1. XG-PON2 will be addressed at a later phase, when the technology becomes more mature. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.652] Recommendation ITU-T G.652 (2009), *Characteristics of a single-mode optical fibre and cable*. +- [ITU-T G.657] Recommendation ITU-T G.657 (2012), *Characteristics of a bending-loss insensitive single-mode optical fibre and cable for the access network*. +- [ITU-T G.703] Recommendation ITU-T G.703 (2016), *Physical/electrical characteristics of hierarchical digital interfaces*. +- [ITU-T G.808.1] Recommendation ITU-T G.808.1 (2014), *Generic protection switching – Linear trail and subnetwork protection*. +- [ITU-T G.810] Recommendation ITU-T G.810 (1996), *Definitions and terminology for synchronization networks*. +- [ITU-T G.813] Recommendation ITU-T G.813 (2003), *Timing characteristics of SDH equipment slave clocks (SEC)*. + +| | | +|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T G.902] | Recommendation ITU-T G.902 (1995), Framework Recommendation on functional access networks (AN) – Architecture and functions, access types, management and service node aspects. | +| [ITU-T G.982] | Recommendation ITU-T G.982 (1996), Optical access networks to support services up to the ISDN primary rate or equivalent bit rates. | +| [ITU-T G.983.1] | Recommendation ITU-T G.983.1 (2005), Broadband optical access systems based on Passive Optical Networks (PON). | +| [ITU-T G.983.2] | Recommendation ITU-T G.983.2 (2005), ONT management and control interface specification for B-PON. | +| [ITU-T G.983.3] | Recommendation ITU-T G.983.3 (2001), A broadband optical access system with increased service capability by wavelength allocation. | +| [ITU-T G.984.1] | Recommendation ITU-T G.984.1 (2008), Gigabit-capable passive optical networks (GPON): General characteristics. | +| [ITU-T G.984.2] | Recommendation ITU-T G.984.2 (2003), Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification. | +| [ITU-T G.984.3] | Recommendation ITU-T G.984.3 (2014), Gigabit-capable Passive Optical Networks (G-PON): Transmission convergence layer specification. | +| [ITU-T G.984.4] | Recommendation ITU-T G.984.4 (2008), Gigabit-capable passive optical networks (G-PON): ONT management and control interface specification. | +| [ITU-T G.984.5] | Recommendation ITU-T G.984.5 (2007), Gigabit-capable Passive Optical Networks (G-PON): Enhancement band. | +| [ITU-T G.984.5 Amd.1] | Recommendation ITU-T G.984.5 Amd.1 (2009), Gigabit-capable Passive Optical Networks (G-PON): Enhancement band, plus Amendment 1. | +| [ITU-T G.984.6] | Recommendation ITU-T G.984.6 (2008), Gigabit-capable passive optical networks (GPON): Reach extension. | +| [ITU-T G.987] | Recommendation ITU-T G.987 (2012), 10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations, and acronyms. | +| [ITU-T G.987.2] | Recommendation ITU-T G.987.2 (2016), 10-Gigabit-capable passive optical networks (XG-PON): Physical media dependent (PMD) layer specification. | +| [ITU-T G.987.3] | Recommendation ITU-T G.987.3 (2014), 10-Gigabit-capable passive optical networks (XG-PON): Transmission Convergence (TC) layer specification. | +| [ITU-T G.988] | Recommendation ITU-T G.988 (2012), ONU management and control interface (OMCI) specification. | +| [ITU-T G.8261] | Recommendation ITU-T G.8261/Y.1361 (2013), Timing and synchronization aspects in packet networks. | +| [ITU-T G.8262] | Recommendation ITU-T G.8262/Y.1362 (2015), Timing characteristics of synchronous Ethernet equipment slave clock. | + +| | | +|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T J.185] | Recommendation ITU-T J.185 (2012), Transmission equipment for transferring multi-channel television signals over optical access networks by frequency modulation conversion. | +| [ITU-T J.186] | Recommendation ITU-T J.186 (2008), Transmission equipment for multi-channel television signals over optical access networks by sub-carrier multiplexing (SCM). | +| [ITU-T Y.2001] | Recommendation ITU-T Y.2001 (2004), General overview of NGN. | +| [ITU-T Y.2201] | Recommendation ITU-T Y.2201 (2009), Requirements and capabilities for ITU-T NGN. | +| [DSLF TR-156] | Broadband Forum TR-156 (2008), Using GPON Access in the context of TR-101. | +| [IEC 60825-2] | IEC 60825-2 (2007), Safety of laser products – Part 2: Safety of optical fibre communication systems (OFCs). | +| [IEEE 1588] | IEEE 1588-2008, IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. | +| [MEF 10.1] | MEF 10.1 (2006), Ethernet Service Attributes Phase 2. | + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +See clause 3 of [ITU-T G.987]. + +## 3.2 Terms defined in this Recommendation + +None. + +# 4 Abbreviations and acronyms + +See clause 4 of [ITU-T G.987]. + +In addition, this Recommendation uses the following abbreviations: + +| | | +|---------|----------------------------------------------| +| FTTO | Fibre To The Office | +| MTU | Multi-Tenant Unit | +| XGS-PON | 10Gbit/s Symmetrical Passive Optical Network | +| XTC | XG-PON Transmission Convergence | + +# 5 Architecture of the optical access network + +## 5.1 Network architecture + +The optical section of a local access network system can be either active or passive and its architecture can be either point-to-point or point-to-multipoint. Figure 5-1 shows the considered architectures, which can be fibre to the home (FTTH), fibre to the cell site (FTTCell), fibre to the building/curb (FTTB/C), fibre to the cabinet (FTTCab), etc. The optical distribution network (ODN) is common to all the architectures shown in Figure 5-1; hence, the commonality of this system has the potential to generate large worldwide volumes. + +![Diagram of network architecture showing three FTTx scenarios (FTTH/Cell, FTTB/C, and FTTCab) connected to a central OLT. FTTH/Cell uses a single fibre from ONU to OLT. FTTB/C and FTTCab use a combination of copper and fibre, with NT and ONU components. The diagram is divided into Home network (left of UNI) and Access network (right of UNI, ending at SNI).](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +ONU Optical network unit + OLT Optical line termination + NT Network termination + UNI User network interface + SNI Service node interface + +G.987.1(10)\_F5-1 + +Diagram of network architecture showing three FTTx scenarios (FTTH/Cell, FTTB/C, and FTTCab) connected to a central OLT. FTTH/Cell uses a single fibre from ONU to OLT. FTTB/C and FTTCab use a combination of copper and fibre, with NT and ONU components. The diagram is divided into Home network (left of UNI) and Access network (right of UNI, ending at SNI). + +**Figure 5-1 – Network architecture** + +NOTE – An ONU supporting FTTH has been commonly referred to as ONT (see [ITU-T G.987]). + +The differences among these FTTx options are mainly due to the different services supported and the different locations of the ONUs rather than the ODN itself, so they can be treated as one in this Recommendation. It must be noted that a single OLT optical interface might accommodate a combination of several scenarios described hereafter. + +XG-PON should extend the [ITU-T G.984.6] reach extenders capability, inherited from the ITU-T G.984.x series of Recommendations to produce extra optical budget to achieve longer distances and/or additional passive split. + +### 5.1.1 FTTB scenario + +The FTTB scenario is divided into two scenarios, one for multi-dwelling units (MDU) and the other for businesses or mixed environments, multi-tenant units (MTUs). Each scenario has the following service categories: + +##### 5.1.1.1 FTTB for MDU-served residential users + +- Asymmetric broadband services (e.g., IPTV, digital broadcast services, video on demand (VoD), file download, etc.). +- Symmetric broadband services (e.g., content broadcast, e-mail, file exchange, distance learning, telemedicine, online-games, etc.). +- POTS – The access network must be able to provide, in a flexible way, narrow-band telephone services using either emulation (complete replication of a legacy service) or simulation (providing a service that is almost the same as the legacy service). + +##### 5.1.1.2 FTTB for MTU-served business users + +- Symmetric broadband services (e.g., group software, content broadcast, e-mail, file exchange, etc.). +- POTS – The access network must be able to provide, in a flexible way, narrow-band telephone services using either emulation (complete replication of a legacy service) or simulation (providing a service that is almost the same as the legacy service). +- Private line – The access network must be able to provide, in a flexible way, private-line services at several rates. + +#### **5.1.2 FTTCurb and FTTCab scenario** + +Within this scenario, the following service categories have been considered: + +- Asymmetric broadband services (e.g., IPTV, digital broadcast services, VoD, file download, online-games, etc.). +- Symmetric broadband services (e.g., content broadcast, e-mail, file exchange, distance learning, telemedicine, etc.). +- POTS – The access network must be able to provide, in a flexible way, narrow-band telephone services using either emulation (complete replication of a legacy service) or simulation (providing a service that is almost the same as the legacy service). +- xDSL backhaul. + +#### **5.1.3 FTTH scenario** + +Within this scenario, the following service categories have been considered: + +- Asymmetric broadband services (e.g., IPTV, digital broadcast services, VoD, file download, etc.). +- Symmetric broadband services (e.g., content broadcast, e-mail, file exchange, distance learning, telemedicine, online-games, etc.). +- POTS – The access network must be able to provide, in a flexible way, narrow-band telephone services using either emulation (complete replication of a legacy service) or simulation (providing a service that is almost the same as the legacy service). + +#### **5.1.4 FTTO scenario** + +Fibre to the office (FTTO) addresses business ONU dedicated to a small business customer. Within this scenario, the following service categories have been considered: + +- Symmetric broadband services (e.g., group software, content broadcast, e-mail, file exchange, etc.). +- POTS – The access network must be able to provide, in a flexible way, narrow-band telephone services using either emulation (complete replication of a legacy service) or simulation (providing a service that is almost the same as the legacy service). +- Private line – The access network must be able to provide, in a flexible way, private line services at several rates. + +#### **5.1.5 FTTCell wireless scenario** + +Within this scenario, the ONU will be called a cell-site backhauling unit (CBU) and will have to offer connectivity to wireless base stations: + +- symmetric TDM services (e.g., 2G cell site backhaul); +- symmetric/asymmetric packet-based broadband services (e.g., 3G/4G cell-site backhaul); +- hot spots. + +Figure 5-2 represents exemplary scenarios of XG-PON applications. + +![Figure 5-2: A summary of some XG-PON scenarios. The diagram shows various deployment scenarios for XG-PON. On the left, scenarios are grouped into 'Cell site' (FTTCell with CBU), 'Business' (FTTB with MTU, FTTO with SBU), and 'Residential' (FTTH with SFU, FTTB with MDU, FTTCurb/Cab with ONU). These units connect to optical splitters, which then connect to XG-PON OLTs. The OLTs are connected to a central 'Aggregation switch'. A label 'G.987.1(10)_F5-2' is in the bottom right.](d4af765160d04ecef538e5066006dc77_img.jpg) + +Figure 5-2: A summary of some XG-PON scenarios. The diagram shows various deployment scenarios for XG-PON. On the left, scenarios are grouped into 'Cell site' (FTTCell with CBU), 'Business' (FTTB with MTU, FTTO with SBU), and 'Residential' (FTTH with SFU, FTTB with MDU, FTTCurb/Cab with ONU). These units connect to optical splitters, which then connect to XG-PON OLTs. The OLTs are connected to a central 'Aggregation switch'. A label 'G.987.1(10)\_F5-2' is in the bottom right. + +Figure 5-2 – A summary of some XG-PON scenarios + +### 5.1.6 Environment conditions in outdoor scenarios + +For supporting the wide range of scenarios and applications, optical parameters for the OLT and the ONU should be determined to allow an outdoor operation. + +## 5.2 Reference configuration + +A high level and simple reference configuration of XG-PON is depicted in Figure 5-3, which shows a very similar high level reference configuration as in the ITU-T G.983.x and ITU-T G.984.x series of Recommendations. + +![Figure 5-3: High-level reference configuration of XG-PON. The diagram shows a high-level architecture. On the 'User side', there are UNIs (T Reference point) connected to ONUs and an AF (Access Function). The ONUs connect to an R/S (Reference point) which is part of the ODN (Optical Distribution Network). The ODN connects to an S/R (Reference point) which is part of the OLT. The OLT connects to 'Service node functions' at the SNI (V) reference point. Above the OLT and ODN is an 'Access network management' block. The entire system is divided into 'User side' and 'Network side' by a double-headed arrow at the bottom. A label 'G.987.1(10)_F5-3' is in the bottom right.](08441fa90c5fd11994626f662ac13f19_img.jpg) + +Figure 5-3: High-level reference configuration of XG-PON. The diagram shows a high-level architecture. On the 'User side', there are UNIs (T Reference point) connected to ONUs and an AF (Access Function). The ONUs connect to an R/S (Reference point) which is part of the ODN (Optical Distribution Network). The ODN connects to an S/R (Reference point) which is part of the OLT. The OLT connects to 'Service node functions' at the SNI (V) reference point. Above the OLT and ODN is an 'Access network management' block. The entire system is divided into 'User side' and 'Network side' by a double-headed arrow at the bottom. A label 'G.987.1(10)\_F5-3' is in the bottom right. + +Figure 5-3 – High-level reference configuration of XG-PON + +In addition to Figure 5-3, when XG-PON is deployed with an RF video overlay service, the ODN can use a WDM device or an optical coupler/splitter to combine XG-PON and RF video signals. The coupler/splitter can optionally be used to provide a split at the central office (CO). Such architectures are depicted in Figures 5-5 and 5-6. + +![Figure 5-4: Reference access network architecture diagram. The diagram shows a PON System containing an OLT, ONUs, and an optical distribution network (ODN). The ODN is divided into a Composite ODN and a Simple ODN. The Composite ODN consists of an ODS (Optical Distribution Segment) and an OTL (Optical Transmission Line) connected by a Splitter and a RE (Reach Extender). The Simple ODN consists of an ODS and a Splitter. The OLT is connected to the SNI (Service Network Interface) and the ONUs are connected to the UNI (User Network Interface). The Access network (AN) [ITU-T G.902] is shown at the bottom, spanning from the ONUs to the SNI. The diagram is labeled G.987.1(10)_F5-4.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Figure 5-4: Reference access network architecture diagram. The diagram shows a PON System containing an OLT, ONUs, and an optical distribution network (ODN). The ODN is divided into a Composite ODN and a Simple ODN. The Composite ODN consists of an ODS (Optical Distribution Segment) and an OTL (Optical Transmission Line) connected by a Splitter and a RE (Reach Extender). The Simple ODN consists of an ODS and a Splitter. The OLT is connected to the SNI (Service Network Interface) and the ONUs are connected to the UNI (User Network Interface). The Access network (AN) [ITU-T G.902] is shown at the bottom, spanning from the ONUs to the SNI. The diagram is labeled G.987.1(10)\_F5-4. + +**Figure 5-4 – Reference access network architecture** + +Figure 5-4 depicts the generic optical access network (OAN) reference architecture that applies to the XG-PON. It includes an OLT, ONUs and an optical distribution network between them. As shown in Figure 5-4, an XG-PON ODN can consist of a single passive optical distribution segment (ODS), or a group of passive ODSs interconnected with reach extenders (REs) [ITU-T G.987]. + +### 5.2.1 ODN architectures + +There can be several types of ODN architectures to achieve coexistence between XG-PON1 or XG-PON2 and additional services such as G-PON and video distribution services. Figures 5-5 and 5-6 are reference diagrams of optical access network architectures. The figures assume that wavelength blocking filters (WBFs) are used when XG-PON (1 or 2), G-PON and video are shared within the same ODN. + +Note that these diagrams simply provide reference configurations of the ODN and WBF, and are not intended to limit future designs and implementations. In addition, the coexistence of XG-PON1 and XG-PON2 is outside the scope of this clause since this would not affect WDM configuration. + +![Figure 5-5: Reference optical configuration for XG-PON coexistence with G-PON through WDM1r. The diagram shows four types of ONUs on the left connected to a central 'Splitter' and 'WDM1r' block, which is then connected to three types of OLTs on the right via an 'ODN' (Optical Distribution Network). The ONUs are: 1) ONU (XG-PON) with interfaces IF_XGPON; 2) ONU (XG-PON + video) with interfaces IF_XGPON and IF_Video; 3) ONU (G-PON) with interface IF_GPON; 4) ONU (G-PON + video) with interfaces IF_GPON and IF_Video. Each ONU contains internal components like Logic, Tx, Rx, WBF, and WDM-X or WDM-G. The OLTs are: 1) OLT (XG-PON) with interface IF_XGPON; 2) OLT (G-PON) with interface IF_GPON; 3) OLT (video) with interface IF_Video. The WDM1r block has multiple ports for different wavelengths. A label 'G.987.1(16)_F5-5' is in the bottom right.](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +Figure 5-5: Reference optical configuration for XG-PON coexistence with G-PON through WDM1r. The diagram shows four types of ONUs on the left connected to a central 'Splitter' and 'WDM1r' block, which is then connected to three types of OLTs on the right via an 'ODN' (Optical Distribution Network). The ONUs are: 1) ONU (XG-PON) with interfaces IF\_XGPON; 2) ONU (XG-PON + video) with interfaces IF\_XGPON and IF\_Video; 3) ONU (G-PON) with interface IF\_GPON; 4) ONU (G-PON + video) with interfaces IF\_GPON and IF\_Video. Each ONU contains internal components like Logic, Tx, Rx, WBF, and WDM-X or WDM-G. The OLTs are: 1) OLT (XG-PON) with interface IF\_XGPON; 2) OLT (G-PON) with interface IF\_GPON; 3) OLT (video) with interface IF\_Video. The WDM1r block has multiple ports for different wavelengths. A label 'G.987.1(16)\_F5-5' is in the bottom right. + +**Figure 5-5 – Reference optical configuration for XG-PON coexistence with G-PON through WDM1r** + +![Figure 5-6: Reference optical configuration for XG-PON coexistence through splitter. This diagram is similar to Figure 5-5 but uses a two-stage splitting system. The ONUs are the same as in Figure 5-5. They connect to a 'Splitter (second stage, 1 by M)'. This splitter's output connects to a 'Splitter (first stage, 3 by N)'. The output of the first stage splitter connects to the same three OLTs via an 'ODN'. The OLTs are: 1) OLT (XG-PON) with interface IF_XGPON; 2) OLT (G-PON) with interface IF_GPON; 3) OLT (video) with interface IF_Video. A legend indicates that small black rectangles represent 'Additional filters'. A note at the bottom left defines 'WBF: Wavelength blocking filter'.](4ee27dbf5ef12e7b58b0ef0937bc5a5e_img.jpg) + +Figure 5-6: Reference optical configuration for XG-PON coexistence through splitter. This diagram is similar to Figure 5-5 but uses a two-stage splitting system. The ONUs are the same as in Figure 5-5. They connect to a 'Splitter (second stage, 1 by M)'. This splitter's output connects to a 'Splitter (first stage, 3 by N)'. The output of the first stage splitter connects to the same three OLTs via an 'ODN'. The OLTs are: 1) OLT (XG-PON) with interface IF\_XGPON; 2) OLT (G-PON) with interface IF\_GPON; 3) OLT (video) with interface IF\_Video. A legend indicates that small black rectangles represent 'Additional filters'. A note at the bottom left defines 'WBF: Wavelength blocking filter'. + +**Figure 5-6 – Reference optical configuration for XG-PON coexistence through splitter** + +NOTE – In case coexistence of XG-PON through a splitter is envisioned, strengthened filtering or additional filtering (as shown in Figure 5-6 revised as above) should be used at OLT for implementation of the WDM-X-L and WDM-G-L to offer the required isolation. Those filters when part of OLT implementation choices are out of the scope of [ITU-T G.987]. + +Functions of WBFs and WDMs that enable the G-PON and XG-PON coexistence, as shown in Figures 5-5 and 5-6, are listed as follows: + +| | | +|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Tx | Optical transmitter | +| Rx | Optical receiver | +| V-Tx | Video transmitter | +| V-Rx | Video receiver | +| WBF | Wavelength blocking filter for blocking interference signals to Rx. | +| WBF-V | Wavelength blocking filter for blocking interference signals to V-Rx. | +| WDM-X | WDM filter in XG-PON ONU to combine/isolate the wavelengths of XG-PON upstream and downstream. | +| WDM-X' | WDM filter in XG-PON ONU to combine/isolate the wavelengths of XG-PON upstream and downstream and isolate the video signal(s). | +| WDM-G | WDM filter in G-PON ONU to combine/isolate the wavelengths of G-PON upstream and downstream. | +| WDM-G' | WDM filter in G-PON ONU to combine/isolate the wavelengths of G-PON upstream and downstream and isolate the video signal(s). | +| WDM-X-L | WDM filter in XG-PON OLT to combine/isolate the wavelengths of XG-PON upstream and downstream. | +| WDM-G-L | WDM filter in G-PON OLT to combine/isolate the wavelengths of G-PON upstream and downstream of one or more channels. | +| WDM1r | WDM filter that may be located in the central office to combine/isolate the wavelengths of XG-PON and G-PON signals and which occasionally combines the video signals. | + +### 5.2.2 Operating wavelength for G-PON and XG-PON + +The wavelength range of the XG-PON1 downstream signal on a single-fibre system is from 1575-1580 nm (1575-1581 nm for outdoor application), and the range of upstream signal for XG-PON1 is from 1260-1280 nm. This clause redefines the reserved wavelength range and specifies the tolerance for interference signals of XG-PON1 ONUs to enable the coexistence of XG-PON and additional services such as G-PON and video services. + +Figure 5-7 and Table 5-1 define the wavelength allocation plan including the wavelength bands reserved for additional services. The wavelength range of the XG-PON downstream signal is referred to as the "basic band." Reserved bands are referred to as the "enhancement band." Applications for the enhancement band may include G-PON and/or video services. The wavelength range for video services remains the same range as defined in [ITU-T G.983.3]. + +A guard band separates the XG-PON upstream and downstream from the enhancement band. The interference between signals in these two bands causes signal degradation among each other, so it must be reduced to a negligible level. WBFs are used to obtain the required isolation outside the guard band. The wavelength values specified in Table 5-1 take into account guard bands that can be achieved with commercially available low-cost WBFs. + +NOTE – Wavelengths in the enhancement band may be used not only for downstream but also for upstream signal transmission in the WDM scheme. + +1.3 μm wavelength band + +![Diagram of the 1.3 μm wavelength band showing XG-PON upstream (1260-1280 nm), a guard band, and Enhancement band (Option 1) starting at λ1 (1290 nm) up to 1360 nm.](5cab96b2d23174c25919840ecd50aa48_img.jpg) + +Diagram of the 1.3 μm wavelength band. It shows a segment from 1260 nm to 1360 nm. The first part (1260-1280 nm) is labeled 'XG-PON upstream'. This is followed by a 'Guard band' (1280-λ1). The remaining part (λ1-1360 nm) is labeled 'Enhancement band (Option 1)'. The start of the enhancement band is marked as $\lambda 1$ . + +Diagram of the 1.3 μm wavelength band showing XG-PON upstream (1260-1280 nm), a guard band, and Enhancement band (Option 1) starting at λ1 (1290 nm) up to 1360 nm. + +Intermediate wavelength band + +![Diagram of the Intermediate wavelength band showing Enhancement band (Option 2) from 1360 nm to 1480 nm.](1a827b10290f33d4fec04d0e8ef7a897_img.jpg) + +Diagram of the Intermediate wavelength band. It shows a segment from 1360 nm to 1480 nm, which is entirely labeled 'Enhancement band (Option 2)'. + +Diagram of the Intermediate wavelength band showing Enhancement band (Option 2) from 1360 nm to 1480 nm. + +1.5 μm wavelength band + +![Diagram of the 1.5 μm wavelength band showing Enhancement band (Option 3) from 1480 nm to 1560 nm, a guard band, Basic band XG-PON downstream (1575-1580 nm), another guard band, and Enhancement band (Option 4) from λ5 to λ6.](a83ba9e3e2c1e21dd69953a7b09e45b4_img.jpg) + +Diagram of the 1.5 μm wavelength band. It shows a segment from 1480 nm to λ6. The first part (1480-1560 nm) is labeled 'Enhancement band (Option 3)'. This is followed by a 'Guard band' (1560-1575 nm). The next part (1575-1580 nm) is labeled 'Basic band XG-PON downstream'. This is followed by another 'Guard band' (1580-λ5). The final part (λ5-λ6) is labeled 'Enhancement band (Option 4)'. A small code 'G.987.1(16)\_F5-7' is visible at the bottom right. + +Diagram of the 1.5 μm wavelength band showing Enhancement band (Option 3) from 1480 nm to 1560 nm, a guard band, Basic band XG-PON downstream (1575-1580 nm), another guard band, and Enhancement band (Option 4) from λ5 to λ6. + +**Figure 5-7 – Wavelength allocation** + +**Table 5-1 – Parameters for wavelength allocation in Figure 5-7** + +| Items | Notation | Unit | Nominal value | Application examples | +|-------------|--------------------------------|------|------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | XG-PON1 Upstream | | | | +| Lower limit | – | nm | 1260 | For use in XG-PON1 upstream. | +| Upper limit | – | nm | 1280 | | +| | Enhancement band (option 1) | | | | +| Lower limit | $\lambda 1$ | nm | 1290 | For use in G-PON upstream
(Reduced option: 1290-1330 nm). | +| Upper limit | – | nm | 1330 | | +| | Enhancement band (option 2) | | | | +| Lower limit | – | nm | 1360
(Informative) | For future use.
NOTE – The values are informative. The loss in this band is not guaranteed in optical branching components for PON (i.e., power splitters) specified in [b-ITU-T G.671] nor in optical fibres specified as [ITU-T G.652] A&B (non-low-water-peak fibres). | +| Upper limit | – | nm | 1480
(Informative) | | +| | Enhancement band (option 3) | | | | +| Lower limit | – | nm | 1480 | For use in G-PON downstream (1480-1500 nm) and/or video distribution service (1550-1560 nm). | +| Upper limit | – | nm | 1560 | | +| | XG-PON downstream (Basic band) | | | | +| Lower limit | – | nm | 1575 | For use in XG-PON1 downstream (Note 2) | +| Upper limit | – | nm | 1580 | | + +**Table 5-1 – Parameters for wavelength allocation in Figure 5-7** + +| Items | Notation | Unit | Nominal value | Application examples | +|-----------------------------|-------------|------|---------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Enhancement band (Option 4) | | | | For future use.
NOTE – The upper-limit value is determined as an operator choice from TBD (to be determined) to 1625 nm, considering the following factors:
bending loss of optical fibre that increases at longer wavelengths;
loss of a filter that separates/combines a monitoring signal and user signal(s) (if an optical monitoring system is used) | +| Lower limit | $\lambda 5$ | nm | TBD | | +| Upper limit | $\lambda 6$ | nm | TBD to 1625 | | + +NOTE 1 – Proper guard bands should be considered in the case of multiple wavelengths in the same Enhancement band. +NOTE 2 – Enhanced wavelength band of 1575-1581 nm is allowed in the case of outdoor OLT operations. + +### 5.2.3 User network interface (UNI) and service node interface (SNI) + +As depicted in Figure 5-3, ONU provides the UNI towards end users, while the OLT provides the SNI interface towards the core network. The types of UNI/SNI interfaces depend on the services that the service provider offers. See [ITU-T G.902]. + +- Examples of UNI are described in clause I.1.2. +- Examples of SNI are described in clause I.1.3. + +#### 5.2.4 Interface at reference points S/R and R/S + +The interface at reference points S/R and R/S at OLT and ONU optical port is defined as IFXG-PON. This is a PON-specific interface that supports all the protocol elements necessary to allow transmission between OLT and ONUs. + +#### 5.2.5 Layered structure of XG-PON optical network + +The protocol reference model is divided into physical medium, transmission convergence (TC), and path layers (see [ITU-T G.902] and the ITU-T G.984.x series of Recommendations). An example applied to XG-PON is shown in Table 5-2. In an XG-PON network, the path layer corresponds to the X-GEM encapsulation layer. + +**Table 5-2 – Layered structure of XG-PON network** + +| Path layer | | | | +|----------------------------------|-----------------------|------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmission medium layer (Note) | XTC layer | Adaptation | X-GEM encapsulation | +| | | PON transmission | DBA
X-GEM port bandwidth allocation
QoS handling & T-CONT management
Privacy and security
Frame alignment
Ranging
Burst synchronization
Bit/byte synchronization | +| | Physical medium layer | | E/O adaptation
Wavelength division multiplexing
Fibre connection | + +NOTE – The transmission medium layer must provide the related OAM functions. + +The XTC layer is divided into PON transmission and adaptation sublayers, which correspond to the transmission convergence sublayer of the X-GEM conveying various data types. The PON transmission sublayer terminates the required transmission function on the ODN. The PON-specific functions are terminated by the PON transmission sublayer, and it is not seen from the adaptation sublayer. + +The two layers considered are the physical medium dependent layer and the TC layer. + +# 6 Migration scenarios + +Gigabit PONs such as G-PON (ITU-T G.984.x series of Recommendations) and 1G-EPON ([b-IEEE 802.3]) have been standardized and are now being deployed worldwide. With the ever increasing bandwidth demand from consumer and business applications, the most general requirement for a next-generation PON (NG-PON) is to provide higher bandwidth than Gigabit PON. In addition, given the major investments spent on time and money on deploying Gigabit PON mainly in the fibre infrastructure, NG-PON must be able to protect the investment of the legacy Gigabit PONs by ensuring seamless and smooth migration capability for subscribers from Gigabit PON to NG-PON. Coexistence between XG-PON and G-PON, which is addressed by this Recommendation, is enabled through the wavelength band plan enhancements specified in [ITU-T G.984.5 Amd.1], which also provides optional overlay capability of broadcast TV on a separate wavelength. Coexistence with other legacy PON systems is for further study and will not be covered in this version of this Recommendation. + +There are several migration scenarios to meet different service providers' needs. These reflect recognition that differing service introduction strategies might affect requirements for the NG-PON specifications. This clause describes two likely migration scenarios: + +### PON brown field migration scenario + +PON brown field scenario in this Recommendation refers to the deployment scenario where a PON system has already been deployed and network operators decide to leverage this existing fibre infrastructure to offer higher bandwidth carrier services, using XG-PON. Some subscribers on an existing Gigabit PON system might require an upgrade to such higher speed tier service and the network operator may therefore choose to move over these subscribers to the XG-PON system, while other subscribers remain on the Gigabit PONs. At a certain point, some network operators may eventually perform a 'forced migration' from Gigabit PON to XG-PON when the number of Gigabit PON subscribers becomes low. It is likely that both Gigabit PONs and XG-PONs will continue to + +coexist for a relative long time in this scenario. In a similar, but slightly different migration scenario, a network operator might want to replace an existing Gigabit PON with an XG-PON completely. In this case, it would still make sense to run both Gigabit PON and XG-PON at the same time and update customers one at a time. But, the upgrade window is rather much shorter. + +General requirements for this scenario are as follows: + +- coexistence between Gigabit PON and XG-PON on the same fibre must be supported for the case that the fibre resource is not necessarily abundant; +- service interruption for the non-upgrade subscribers should be minimized; +- XG-PON must support/emulate all G-PON legacy services in the case of full migration. + +### PON green field migration scenario + +Renovating the access network to FTTx infrastructure is the biggest investment of service providers and may take a long time. When XG-PON technology becomes mature, service providers might be interested in using XG-PON to replace copper-based infrastructure or to deploy in a brand new development area for the benefit of higher bandwidth and/or higher splitting ratio. An area where Gigabit PON had not been deployed before is referred to as "PON green field". This scenario may help service providers achieve better economics while supporting the same or better bandwidth offer per user as Gigabit PON. In this scenario, the requirement of coexistence with Gigabit PONs is not necessary. + +## 6.1 Migration from legacy PON to XG-PON + +To assure this smooth migration capability, overlay through WDM technology in compliance to optical wavelength allocation described in [ITU-T G.984.5 Amd.1] must be implemented in all ONUs. It will, of course, remain the choice of the operator whether to use this capability or rather run a full PON active devices replacement from day 1 of an upgrade process. + +In the transition period, to get simultaneous G-PON and XG-PON working, a WDM1r combiner/splitter is installed in the network, as illustrated in Figure 6-1. + +![Diagram illustrating the coexistence of G-PON and XG-PON with video overlay option. A central WDM1r combiner/splitter is connected to an XG-PON OLT, a GPON OLT, and a 1550 RF video source. The WDM1r is connected to a split fiber network serving multiple ONUs and XG-ONUs. Text indicates that a 32-way split for G-PON gives ~80/40 Mbit/s per customer, while for XG-PON it gives ~320/80 Mbit/s per customer. A key at the bottom shows the wavelength allocation: 1490 nm/1310 nm for GPON (ONU and GPON OLT) and XG-PON (XG-ONU and XG-PON OLT).](40f30e4d577a17052f8b1e6dc802a0d8_img.jpg) + +e.g., G-PON with 32-way split gives each customer sustained bandwidth ~80/40 Mbit/s + +XG-PON1 with same split gives each customer sustained bandwidth ~320/80 Mbit/s + +Key: + +1490 nm/1310 nm GPON: ONU, GPON OLT + +XG-PON: XG-ONU, XG-PON OLT + +G.987.1(10)\_F6-1 + +Diagram illustrating the coexistence of G-PON and XG-PON with video overlay option. A central WDM1r combiner/splitter is connected to an XG-PON OLT, a GPON OLT, and a 1550 RF video source. The WDM1r is connected to a split fiber network serving multiple ONUs and XG-ONUs. Text indicates that a 32-way split for G-PON gives ~80/40 Mbit/s per customer, while for XG-PON it gives ~320/80 Mbit/s per customer. A key at the bottom shows the wavelength allocation: 1490 nm/1310 nm for GPON (ONU and GPON OLT) and XG-PON (XG-ONU and XG-PON OLT). + +Figure 6-1 – Example of coexistence of G-PON and XG-PON with video overlay option + +Any coexistence combination of XG-PON may be used. Specifically, XG-PON can coexist with RF video overlay only; the required WDM1r characteristics and performances can be found in [ITU-T G.984.5 Amd.1]. + +## 6.2 Migration from XG-PON1 to XG-PON2 + +The need of coexistence between XG-PON1 and XG-PON2 still requires further study and therefore will not be addressed in this version, but rather in a future revision. Regardless of the need of the coexistence requirement, it is desirable to support a common TC layer for XG-PON1 and XG-PON2 derived from G-PON's TC with the necessary enhancements. + +## 6.3 Overlay of XG-PON or hybrid XG-PON + +It is possible to overlay multiple XG-PONs on the same ODN to create even higher capacity using WDM. In such extensions, spectrum allocation is critical to make this overlay approach work. The requirement for overlaying XG-PON or hybrid XG-PON is for further study in a future revision. + +## 6.4 RE architecture options + +This clause focuses on mid-span architectures, since single-end solutions such as those described in [ITU-T G.984.6] will be part of each dedicated technology options and, as such, will be treated as OLT implementation options. + +In the XG-PON world, two main architectures involving reach extenders are required, as described in Figure 6-2: + +- one for deployments in which network consolidation will take place when migrating from G-PON to XG-PON; +- the other for deployments in which REs have already been deployed for the G-PON systems, in which case two situations will occur depending on the early RE technology deployed: + - either the RE had from the start the capability to cover G-PON and XG-PON requirements; or + - the early RE has to be replaced by what will onwards be called a "combo" RE. + +![Figure 6-2 – RE migration scenarios. The diagram shows two use cases for G-PON / XG-PON overlay. Use case 1 shows a G-PON OLT connected to an ODN via a WDM1r, with a mid-span extender and an XG-OLT connected to the same ODN. Use case 2 shows a G-PON OLT connected to an ODN via a mid-span extender, with a WDM1r and an XG-OLT connected to the same ODN.](1a85642ed2356d183ce598f2c8b3ee8b_img.jpg) + +Use case 1: G-PON / XG-PON Overlay with mid span XG-PON only extender + +Use case 2: G-PON / XG-PON Overlay with a mid span extender + +G.987.1(10)\_F6-2 + +Figure 6-2 – RE migration scenarios. The diagram shows two use cases for G-PON / XG-PON overlay. Use case 1 shows a G-PON OLT connected to an ODN via a WDM1r, with a mid-span extender and an XG-OLT connected to the same ODN. Use case 2 shows a G-PON OLT connected to an ODN via a mid-span extender, with a WDM1r and an XG-OLT connected to the same ODN. + +Figure 6-2 – RE migration scenarios + +The goal of using a mid-span RE is to provide additional optical budget with normal OLT and ONU performances, in order to enable, without it being at its maximum, the use of simultaneous full capability of the technology for both distance and split. The use of such REs must not require any change in the OLT and ONU requirements in order to avoid any interoperability issue. Many further options that are under development for [ITU-T G.984] will also be considered in the XG-PON environment, addressing the capability to save fibres in the OTL section. These are for further study. + +# 7 Service requirements + +## 7.1 Services + +Telecommunication networks are evolving from traditional circuit-based networks to the packet-based (i.e., IP/Ethernet-oriented) next-generation networks (NGNs), which can effectively provide various services with a common platform (see [ITU-T Y.2201] and [ITU-T Y.2001]). In addition to emerging packet-based services, NGN also provides legacy services such as TDM and POTS using either emulation (complete replication of a legacy service) or simulation (providing a service that is almost the same as the legacy service). + +NG-PON is required to fully support various services for residential subscribers, business customers, and mobile backhauling application through its high quality of service and high bit-rate capability. NG-PON should support legacy services, such as POTS and T1/E1 using emulation and/or simulation, as shown in Table 7-1, to harmonize with the concept of NGN. + +- The emulation option delivers packet-formatted traffic through the PON network, i.e., from ONU to OLT, and possibly through some level of aggregation, then converts back to the relevant legacy format to hand it off to the legacy network. +- The simulation option is an end-to-end packet delivery starting at CPE terminal adaptation device or ONU, to the NG-PON access and the NGN packet network. + +Table 7-1 summarizes examples of NG-PON services. + +**Table 7-1 – Examples of NG-PON services** + +| No. | Service | | Remark | +|-----|----------------|-------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Telephony | VoIP | | +| 2 | | POTS | Mean signal transfer delay time between T-V (or (a)-V) should be less than 1.5 ms. If echo cancellation is used in the network, the mean signal transfer delay time between T-V (or (a)-V) on the PON-based system may be longer, provided end-to-end transfer delay requirements are met.
8 kHz reference has to be provided. (see Note)
Signal on the T reference point and V reference point must be continuous.
Emulation and/or simulation, as defined in [ITU-T Y.2201], is assumed.
e.g., packetized voice at ONU | +| 3 | TV (real-time) | IPTV | To be transported using IP multicast/unicast | +| | | Digital TV broadcasting | Transported using RF-video overlay (see [ITU-T G.983.3], [ITU-T J.185] and [ITU-T J.186]) | + +**Table 7-1 – Examples of NG-PON services** + +| No. | Service | | Remark | +|---------------------------------------------------------------------------------------------|----------------------------|----|-------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | | | +| 4 | Leased line | T1 | Bearer rate is 1.544 Mbit/s.
Mean signal transfer delay time between T-V (or (a)-V) should be less than 1.5 ms.
Emulation is assumed primarily. | +| 5 | | E1 | Bearer rate is 2.048 Mbit/s.
Mean signal transfer delay time between T-V (or (a)-V) should be less than 1.5 ms.
Emulation is assumed primarily. | +| 6 | High speed Internet access | | UNI is typically Gigabit Ethernet | +| 7 | Mobile backhaul | | Accurate frequency/phase/time synchronization should be supported. | +| 8 | L2 VPN Services | | such as Ethernet services, etc. | +| 9 | IP Services | | such as L3 VPN, and VoIP, etc. | +| NOTE – See [ITU-T G.810], [ITU-T G.813], [ITU-T G.8261], [ITU-T G.703], and [ITU-T G.8262]. | | | | + +For business applications, XG-PON should provide access to Ethernet services such as point-to-point, multipoint-to-multipoint and rooted-multipoint Ethernet virtual connection (EVC) services (also called E-Line, E-LAN and E-Tree, respectively). XG-PON shall also support accurate frequency/phase/time synchronization for the mobile backhaul application. + +As a general requirement, XG-PON needs to support IPv6. + +## 7.2 Maximum/mean signal transfer delay tolerance + +XG-PON must accommodate services that require a maximum mean signal transfer delay of 1.5 ms. + +Specifically, XG-PON systems must have a maximum mean signal transfer delay time of less than 1.5 ms between T-V (or (a)-V, depending on the operator's preference). See clause 12 in [ITU-T G.982]. Delays introduced by the adaptation functions such as circuit emulation are not included in this value. + +Although a section of the delay measurement is T-V for FTTH system or (a)-V for the other application in [ITU-T G.982], in a XG-PON system, the reference points are not restricted by the system configuration. + +## 7.3 Maximum Ethernet packet size + +XG-PON technology shall support Ethernet frames having a maximum length of 2000 bytes. Jumbo frames with lengths beyond 2000 bytes and up to 9000 bytes (generally recognized as the upper limit for jumbo frames) should be optionally supported. If jumbo frames beyond 2000 bytes are used for non-delay-sensitive services on the same PON, the delay-sensitive services and packet network synchronization shall not be degraded by jumbo frame transport. + +## 7.4 Synchronization features and quality + +Network operators are motivated to leverage the XG-PON infrastructure and systems to deliver high bandwidth to mobile cell sites. This requires accurate synchronization and timing delivery to the cell sites. Typically, T1 or E1 interfaces have been used for backhaul and these provide the necessary synchronization and timing references. However, it is increasingly important to provide accurate synchronization and timing over packet interfaces (e.g., Ethernet) especially to the cell sites where no T1/E1 interface is available driven by 3G/4G wireless. + +XG-PON OLTs for this application must be able to receive a high quality timing clock as well as to serve as master timing source for the ONUs. The ONUs must be able to distribute the accurate timing/synchronization to the cell sites to meet the cell site frequency/phase/time synchronization requirement. + +For this purpose, XG-PON shall provide a function to transfer the accurate phase/time information between OLT and ONUs taking into account the propagation delay and the processing delay between them. Additional, inaccuracy incurred in the PON section shall be much less than the reference accuracy to leave margin for other network sections. Table II.1 contains a summary of the synchronization requirements for different wireless technologies; see clause IV.2.2 of [ITU-T G.8261]. + +The mechanisms, for instance as specified in [ITU-T G.8261] and [ITU-T G.8262], for distributing accurate timing to the 3G/4G cell sites are for further study depending on the performance and economics. In view of the extra complexity in delivering timing to applications such as mobile backhaul, the additional functionality might be limited to specific "CBU" ONUs. + +Aspects of clock propagation, frequency and time of day synchronization scenarios, and ESMC messages transport over PON with IEEE 1588v2, are developed respectively in Appendices IV, V and VI. + +## 7.5 Leased line T1/E1 emulation + +T1/E1 emulation services require that the timing of the signal be similar at both ends of the packet network. There are four methods identified in clause 8 of [ITU-T G.8261], and they are: + +- Network synchronous operation – this method relies on a PRC-traceable clock to be available at both ends of the packet network. This method does not preserve the service clock. +- Differential methods – this method encodes the difference between the service clock and the common reference clock and transmits it across the packet network. The service clock is recovered at the far end of the packet network by using a common reference clock available at both ends of the network. +- Adaptive methods – this method relies simply on packet arrival times (or inter-arrival times). Other forms of adaptive methods are available and are based on the use of time stamps and non-linear filtering to achieve better performance. +- Reference clock available at the TDM end systems – this method is a trivial case where both ends of the packet network has access to a timing reference. + +Clause 9.1 of [ITU-T G.8261] specifies the maximum wander network limits for circuit emulation. + +## 7.6 QoS and traffic management + +XG-PON must be capable of supporting multiple existing and emerging services across multiple market segments, such as consumer, business, and mobile backhaul. Like G-PON, XG-PON must provide simultaneous access to packet-based services, such as high speed Internet access, IPTV, and VoIP, as well as legacy services, such as POTS voice and T1/E1. In addition, an XG-PON must provide access to carrier-grade metro Ethernet services, such as point-to-point, multipoint-to-multipoint and rooted-multipoint EVC services, also known as E-Line, E-LAN and E-Tree, + +respectively, defined by the Metro Ethernet Forum (MEF) for business customers. These varieties of services present a broad range of QoS characteristics; therefore, they require systems to provide appropriate traffic management mechanisms. + +For the POTS telephone services, XG-PON must support POTS voice quality with guaranteed fixed bandwidth to meet the low-delay and low-jitter requirements. Similarly, XG-PON must support TDM services such as E1/DS1s for business customers, and mobile backhauling applications with guaranteed fixed bandwidth to meet low-delay, low-jitter, and strict timing requirements. + +To provide access to a variety of packet-based services, such as IPTV, VoIP, L2/L3 VPNs, and high-speed Internet access, XG-PON must provide at least four classes of services to map UNI flows. It is desirable for XG-PON to provide at least six classes of services to map UNI flows. XG-PON must also support drop precedence within at least two traffic classes. + +In addition to priority based classes of services, as indicated above and also specified in [DSLF TR-156], XG-PON ONUs must support rate controlled services (e.g., CIR/PIR) with policing and shaping function in addition to the priority based traffic management, for instance for business applications and mobile backhaul. Business customer ONUs must also support industry specification at UNI ports, such as [MEF 10.1]. However, it is not required for the XG-PON to provide full MAC address learning for the whole Metro-Ethernet network. The XG-PON will utilize the Metro Ethernet network capability to provide full Ethernet services. + +XG-PON must support any mix of residential, business, and mobile backhaul traffic within the same PON as illustrated in Figure 5-2. It must also support a mix of consumer and business users within a multiple subscriber ONU. XG-PON must support a mix of rate based (including CIR/PIR provisioning, policing, shaping, etc.) and priority based traffic management within the same PON and same ONU. + +XG-PON must support N:1 VLAN, 1:1 VLAN, and access to VLAN for business Ethernet service (VBES) service on the same PON. + +# **8 Physical layer requirements** + +The XG-PON architecture is based on single fibre transmission. + +## **8.1 Fibre characteristics** + +This Recommendation is based on deployment using fibre types described in [ITU-T G.652], which is widely used for G-PON. Newer fibre types exhibiting low-bend radius characteristics defined in [ITU-T G.657] should also be compatible for NG-PON deployments. + +## **8.2 Optical wavelengths of XG-PON** + +To achieve a low cost implementation of such a compatibility feature, the retained wavelengths are: + +- for the upstream, the "O- Band", ranging from 1260 to 1280 nm; +- for the downstream, "1577 nm", ranging from 1575 to 1580 nm (extension for outdoor is 1575 to 1581 nm). + +## **8.3 Bit rates** + +XG-PON identifies two transmission speed sets named as follows: + +- XG-PON1: nominally 10 Gbit/s down, 2.5 Gbit/s up; +- XG-PON2: nominally 10 Gbit/s down, 10 Gbit/s up. + +The initial phase of this Recommendation only focuses on the XG-PON1 bit rate. + +Due to the current technology challenges that need to be overcome to obtain low cost 10 Gbit/s upstream burst mode building blocks, XG-PON2 will be specified in a later phase. + +## 8.4 Optical power budget + +Coexistence of Gigabit PON and XG-PON on an ODN featuring a class B+ optical budget is the nominal requirement. With the additional loss introduced by the WDM1r device, two "Nominal" power budget classes between the two IFXG-PON reference points in Figure 5-5 have been selected, i.e., Nominal1 (29 dB) and Nominal2 (31 dB) at BER of 1E-12. In addition, coexistence of Gigabit PON and XG-PON on an ODN featuring C+ optical budget drives the extended power budget requirement, allowing for an additional split in the ODN with appropriate margins, or alternatively an increase in the supported system reach. + +The detailed specifications for nominal classes and the extended class will be addressed in [ITU-T G.987.2]. + +Reach extender based optical budget extensions are discussed in the reach extender section. + +## 8.5 Split ratio + +As many network operators have constructed their ODN infrastructure with 1:32 to 1:64 split for Gigabit PONs, 1:64 split (subject to the overall loss budget) shall be the minimum requirement for XG-PON to allow the coexistence described in clause 6. A generic splitter deployment of Gigabit PONs is shown in Figure 8-1 (a). + +In this model, a single-split architecture is a special case, where $m = 64$ and $n = 1$ and no splitter is needed at the access node. Some network operators expressed their interest in extending the split beyond 1:64 (e.g., 1:128 to 1:256) to improve XG-PON overall economics compared to G-PON. + +This high split ratio is very attractive especially for the 'service-independent introduction scenario'. The higher splitter ratio allows to extend PON in the backhaul section as shown in Figure 8-1 (b) and/or to extend PON towards the end users as shown in Figure 8-1 (c) to provide flexible splitter configurations and efficiently support a variety of deployment scenarios. Considering these options, the XG-PON TDMA control function should support a 256-way (or possibly more) logical split. Physical split in the optical layer must be carefully selected to take into account the maturity and cost-effectiveness of optical devices. Reach extension can be used to increase the loss budget, and thus realize a higher split in the physical layer, especially in the cases presented in Figure 8-1 (b) and Figure 8-1 (c), in addition to extending the system nominal reach. + +![Diagram (a) shows a generic XG-PON configuration. Multiple ONUs are connected to a 1:m splitter. The output of this splitter is connected to a 1:n splitter located within an 'Access node' (indicated by a dashed box). The output of the 1:n splitter is connected to an OLT. The total number of ONUs is indicated as m*n = 32 to 64. Diagram (b) shows an XG-PON configuration with an extra split in the higher access network level. Multiple ONUs are connected to a 1:m splitter. The output of this splitter is connected to a 1:n splitter within an 'Access node'. The output of the 1:n splitter is then connected to a 1:p splitter. The output of the 1:p splitter is connected to a 1:q splitter within a 'Consolidation node', which is then connected to an OLT. The total number of ONUs is indicated as m*n*p*q >> 64. Diagram (c) shows an XG-PON configuration with an extra split in the lower access network level. ONUs are grouped into 'Building, settlement, etc' and connected to 1:n splitters. The outputs of these 1:n splitters are then connected to a 1:m splitter. The output of the 1:m splitter is connected to a 1:n splitter within an 'Access node', which is then connected to an OLT. The total number of ONUs is indicated as r*m*n >> 64.](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg) + +(a) Generic configuration + +(b) Support of extra split in higher access network level + +(c) Support of extra split in lower access network level + +G.987.1(10)\_F8-1 + +Diagram (a) shows a generic XG-PON configuration. Multiple ONUs are connected to a 1:m splitter. The output of this splitter is connected to a 1:n splitter located within an 'Access node' (indicated by a dashed box). The output of the 1:n splitter is connected to an OLT. The total number of ONUs is indicated as m\*n = 32 to 64. Diagram (b) shows an XG-PON configuration with an extra split in the higher access network level. Multiple ONUs are connected to a 1:m splitter. The output of this splitter is connected to a 1:n splitter within an 'Access node'. The output of the 1:n splitter is then connected to a 1:p splitter. The output of the 1:p splitter is connected to a 1:q splitter within a 'Consolidation node', which is then connected to an OLT. The total number of ONUs is indicated as m\*n\*p\*q >> 64. Diagram (c) shows an XG-PON configuration with an extra split in the lower access network level. ONUs are grouped into 'Building, settlement, etc' and connected to 1:n splitters. The outputs of these 1:n splitters are then connected to a 1:m splitter. The output of the 1:m splitter is connected to a 1:n splitter within an 'Access node', which is then connected to an OLT. The total number of ONUs is indicated as r\*m\*n >> 64. + +**Figure 8-1 – XG-PON splitter architecture options** + +## 8.6 Fibre distance + +[ITU-T G.987] introduces the concept of fibre distance and max differential fibre distance. + +XG-PON1 must support the maximum fibre distance of at least 20 km. + +In addition, XG-PON1 TC layer needs to support the maximum fibre distance of 60 km. XG-PON1 TC layer also needs to support the maximum differential fibre distance of up to 40 km. XG-PON1 TC layer also needs to be able to configure the maximum differential fibre distance with a 20 km step. + +# 9 System level requirements + +## 9.1 Power saving and energy efficiency + +Power saving in telecommunication network systems has become an increasingly important concern in the interest of reducing operators' OPEX and reducing the network contribution to greenhouse emission gasses. The primary objective of the power saving function in access networks is to keep providing the lifeline service(s) such as a voice service as long as possible through the use of a backup + +battery when electricity service goes out. For example, some operators require a minimum sustainability for a lifeline interface to operate for 4 to 8 hours after mains outage. Therefore, the XG-PON TC layer shall support better energy efficiency than the [ITU-T G.984] G-PON TC layer whenever compatible with the service requirements, based on the mechanisms derived from [b-ITU-T G-Sup.45]. The secondary goal is to reduce power consumption at all times. It is also an important requirement that we should not sacrifice service quality and user experience. + +Full service mode, dozing mode, and sleep mode are the options that can offer various levels of power saving during the normal mode of operation. In addition, when the mains outage happens, power shedding should be activated for the power saving capability. Realizing that detailed values may vary for XG-PON, [b-ITU-T G-Sup.45] compares the efficiency of each power saving technique as well as the level of service impact. + +## 9.2 Authentication/identification/encryption + +Like G-PON, XG-PON is a shared-medium based system in which all the ONUs on the same PON receive the full data. Accordingly, countermeasures must be taken to avoid impersonation/spoofing and snooping. + +To protect against impersonation/spoofing, authentication and identification mechanisms must be standardized. Use of these mechanisms is optional and will be determined by the operators. They shall include, but will not be limited to: + +- identification of ONU serial number and/or a registration ID used for the ONU registration process; +- authentication of CPE, based on [b-IEEE 802.1X]; +- a strong authentication mechanism is required. + +A simple but secure identification method is also necessary for the recovery from the "sleep" mode when the power saving function is used. + +To protect against snooping at the ONUs, all unicast data in the downstream direction shall be encrypted with a strong and well characterized algorithm, e.g., AES. Therefore, XG-PON shall also provide a reliable key exchange mechanism that is necessary to start an encrypted communication. In the upstream direction the encryption function shall be optional, and implemented upon each operator's requirement. + +## 9.3 Dynamic bandwidth assignment (DBA) + +The XG-PON OLT shall support DBA for the efficient sharing of upstream bandwidth among the connected ONUs and the traffic-bearing entities within the individual ONUs based on the dynamic indication of their activity. The dynamic activity indication can be based on the following two methods: + +- status reporting (SR) DBA employs the explicit buffer occupancy reports that are solicited by the OLT and submitted by the ONUs in response; +- traffic monitoring (TM) DBA employs OLT's observation of the actual traffic amount in comparison with the allocated upstream transmission opportunities. + +The DBA definition comprises the reference model that specifies the ideal bandwidth assignment among the contending upstream traffic-bearing entities under the given traffic load conditions. To allow for effective numerical comparison of the DBA implementations, the standard contains the suggested measures of discrepancy between a DBA implementation and the reference model. To guarantee multi-vendor interoperability, the standard specifies the formats of the SR DBA status enquiries and buffer occupancy reports and the associated protocol. + +The OLT may support any of the dynamic activity indication methods or a combination thereof. It is outside the scope of the requirement specification to define which specific methods have to be supported, or how the OLT utilizes the obtained dynamic activity indication information, or how the OLT upstream scheduler is implemented. + +DBA spreading across several upstream wavelengths in case of overlay XG-PONs or redundancy through dual homing is out of the scope of this Recommendation. + +## 9.4 Eye safety + +Given the higher launched optical power that can be injected on the fibre in the XG-PON era, both at the OLT and the RE level, all necessary mechanisms must be provided to insure that no eye damage can be caused to the end users unaware of the risks, especially if fibre is terminated inside the home. The XG-PON elements need to conform to the following specific classes defined in [IEC 60825-2], respectively: + +- Class 1M for OLT; +- Class 1 for ONU; +- Class 1M for RE. + +# 10 Operational requirements + +## 10.1 ONU management + +### 10.1.1 OMCI managed ONU + +It is highly desirable from the network operation perspective to manage an XG-PON system, i.e., an OLT together with its ONUs, as a single entity, with ONUs being managed via OLTs, wherever possible. Therefore, XG-PON shall support full PON real-time management through ONU management and control functions, where concepts and approaches to be implemented for G-PON (e.g., OMCI) should be reused as much as possible. + +### 10.1.2 Dual managed ONU + +XG-PON shall optionally support collaborative ONU management partition between XG-PON OMCI and remote configuration mechanisms. + +## 10.2 PON supervision + +While it is most important to minimize capital expenditure in the initial stage of FTTH deployment, it is getting more important to reduce operational expenditure as well as to optimize the balance between capital expenditure and operational expenditure according to the full deployment of FTTH. The goal of PON supervision is to reduce the operational expenditure of the PON systems, without significantly increasing the capital expenditure by including as much test and diagnostic capability as possible without compromising the available bandwidth for services. Test and diagnostics must be non-service affecting. Current G-PON's capability of basic testing and diagnostics, which operates at the PON and data layers, with reporting back of alarms and events, shall be taken as a basis for XG-PON. + +The ability to reliably differentiate between optical and electrical faults and establish if the faults are in the ODN or in the electronics is a key operator requirement. Inference can usually be made from the presence (i.e., power or equipment failure), or absence (i.e., fibre failure), of the ONU dying gasp alarm. Several key points for the supervision of XG-PON can be summarized as follows: + +ODN monitoring/checking: Monitoring and on demand checking the condition of ODN independently from a PON system is important to differentiate ODN failures from system failures. It is desirable that such monitoring and checking be available regardless of whether the ONU is in + +service or even connected. An optical time domain reflectometer (OTDR) is a powerful tool for diagnosing such faults in the ODN, and a power meter and light source can be used to aid in the process. Several demarcation devices are under research for further improving the ODN monitoring and checking. + +XG-PON systems would benefit from an ability to automatically and autonomously detect and locate ODN faults. This is especially critical for the feeder section between the serving CO and the first-stage splitter, the length of which can be up to 60 km if an RE is used. + +End-to-end performance monitoring up to the Ethernet layer: End-to-end performance monitoring enables operators to diagnose and register where customer traffic may have been dropped or throttled. Higher layer tools, such as Ethernet performance monitoring, need to support the capability monitoring and verification of ingress and egress traffic flows in PON network elements. + +Proactive versus reactive repair: PON systems with their monitoring and control systems will allow operators to decide on the utilization of proactive or reactive fault repairs in most fault cases. It is of course up to the operators to decide on how to use PON status reports. + +Coexistence of G-PON with XG-PON via WDM1r: It is desirable to immediately localize any problems in the case of Gigabit PON and XG-PON coexistence. Interworking of the supervision function between Gigabit PON and XG-PON is one possibility here, but further studies are necessary. + +# **11 Resilience and protection on ODN** + +Service resilience over previous generations of PONs has not been a strong requirement from operators. XG-PON is required to support a diverse range of high value services (e.g., IPTV) for residential and also business applications with increasing levels of system integration at the head-ends. Failures in the shared portions of the PON will impact multiple customers and services. Consequently, the capability to offer improved service availability figures in XG-PON systems will become increasingly important. + +Individual operators need to determine the best resilience architecture for their specific market and geography. As such, XG-PON should include a range of cost-effective resilience options with both duplex and dual-parented duplex system configurations, as defined in clause 14 of [ITU-T G.984.1], as well as the extensions described in Appendices II and III of that same Recommendation. These resilience schemes should be options available on XG-PON scenarios whether they use mid-span reach extenders or not. Different types of service and specific offerings will require different recovery speeds. These may range from a few tens of milliseconds, for critical and important services such as protected leased lines, up to the order of minutes for residential applications. Note that support for resilience options should not increase the cost of such systems if deployed without resilience options. + +The protection architecture of XG-PON should be considered as one of the means to enhance the reliability of the access networks. However, protection shall be considered as an optional mechanism because its implementation depends on the realization of economical systems. It is also likely to use other methods, such as using alternative access technologies, e.g., LTE (Mobile's 4G standard also known as long term evolution), for backup for better economics. Further information on protection switching can be found in [ITU-T G.808.1]. + +# Appendix I + +## Examples of practical XG-PON system architecture + +(This appendix does not form an integral part of this Recommendation.) + +This appendix provides various examples of practical XG-PON system aspects. First, a review of the typical external interfaces (e.g., UNIs and SNIs) a XG-PON system supports is given. Second, a selection of system architectures is illustrated. Third, the common protocol stack traces are laid out for all these services and systems. + +It should be noted that since XG-PON can address multiple market segments, e.g., consumer, business, and mobile backhaul and the overall scope of all the variants is very large, any single implementation of an ONU will not implement all of the possible features. The objective of this appendix is only to give a comprehensive overview of the options that might be encountered. + +## I.1 Services, UNIs and SNIs + +### I.1.1 Examples of services + +The examples of services that XG-PON can offer are described in clause 7.1. + +### I.1.2 Examples of UNI + +In this appendix, UNI is defined as the interface that includes the following conditions: + +- described by a well-known standard; +- includes a physical layer aspect. + +Some UNIs are provided via an adaptation function, so it is not mandatory that the ONU support those interfaces. + +Examples of UNIs, physical interfaces and services that they provide are shown in Table I.1. + +**Table I.1 – Examples of UNI and services** + +| UNI (Note 1) | Physical interface (Note 2) | Service (Note 3) | +|------------------------------------------|-----------------------------|------------------| +| 1000/100/10BASE- T
[b-IEEE 802.3] | – | Ethernet | +| [b-ITU-T Q.552] | – | POTS | +| [ITU-T G.703] | PDH | DS3, E1, E3 | +| [b-ATIS 0900102] and
[b-ATIS 0600107] | PDH | T1, DS3 | + +NOTE 1 – There are many other services accommodated in XG-PON, but those services do not have specified UNIs. +NOTE 2 – Each item in the "Physical interface" column is illustrated by the corresponding entry in the "UNI" column. +NOTE 3 – The column labelled "Service" shows which services can be supported by the physical interface. + +### I.1.3 Examples of SNI + +In this appendix, SNI is defined as the interface that includes the following conditions: + +- described by a well-known standard; +- includes a physical layer aspect. + +Examples of SNIs, physical interfaces and services that they provide are shown in Table I.2. + +**Table I.2 – Examples of SNI and services** + +| SNI
(Note 1) | Physical interface
(Note 2) | Service
(Note 3) | +|--------------------------|--------------------------------|----------------------------------| +| 1000BASE- [b-IEEE 802.3] | – | Ethernet | +| 10 GigE [b-IEEE 802.3] | – | Ethernet | +| 40 GigE [b-IEEE 802.3] | – | Ethernet | +| 100 GigE [b-IEEE 802.3] | – | Ethernet | +| [b-ITU-T G.965] | V5.2 | POTS, | +| [ITU-T G.703] | PDH, STM-1e | DS3, E1, E3, STM-1, DS1 | +| [b-ITU-T G.957] | STM-1,4,16 | E1, E3, DS1, DS3, GFP, E4, STM-n | +| [b-ATIS 0600107] | PDH | DS1, DS3 | + +NOTE 1 – There are many other services accommodated in XG-PON, but those services do not have specified SNIs. +NOTE 2 – Each item in the "Physical interface" column is illustrated by the corresponding entry in the "SNI" column. +NOTE 3 – The column labelled "Service" shows which services can be supported by the physical interface. + +## I.2 Typical system architectures + +Figure I.1 shows a generic XG-PON system. This system will be developed more specifically in the next six figures. Note, these figures are illustrative examples, not requirements. + +![Figure I.1 – Generic XG-PON system diagram. It shows a CPE connected to an ONU, which is connected to an ODN (Optical Distribution Network), which is connected to an OLT. The OLT is connected to SNI(s). The CPE is connected to UNI(s).](3cc095fb84e92690c9d49d3e17c0f1dc_img.jpg) + +``` + +graph LR + UNI(s) --- CPE + CPE --- ONU + ONU --- ODN((ODN)) + ODN --- OLT + OLT --- SNI(s) + +``` + +G.987.1(10)\_FI-1 + +Figure I.1 – Generic XG-PON system diagram. It shows a CPE connected to an ONU, which is connected to an ODN (Optical Distribution Network), which is connected to an OLT. The OLT is connected to SNI(s). The CPE is connected to UNI(s). + +**Figure I.1 – Generic XG-PON system** + +#### I.2.1 OLT variants + +Figure I.2 shows a pure Ethernet OLT option. In this case, the OLT equipment contains only the XG-PON adaptation function, and typically (but not necessarily) some level of Ethernet aggregation function. It is the simplest form of OLT, and avoids as much specific service linkages as possible. + +![Figure I.2 – Pure OLT scenario diagram. It shows a CPE connected to an ONU, which is connected to an ODN (Optical Distribution Network), which is connected to an OLT. The OLT is connected to SNI and Ethernet. The CPE is connected to UNI(s).](5456ef9dc49ffc9cbb93cf1dd8052884_img.jpg) + +``` + +graph LR + UNI(s) --- CPE + CPE --- ONU + ONU --- ODN((ODN)) + ODN --- OLT + OLT --- SNI + OLT --- Ethernet + +``` + +G.987.1(10)\_FI-2 + +Figure I.2 – Pure OLT scenario diagram. It shows a CPE connected to an ONU, which is connected to an ODN (Optical Distribution Network), which is connected to an OLT. The OLT is connected to SNI and Ethernet. The CPE is connected to UNI(s). + +**Figure I.2 – Pure OLT scenario** + +Figure I.3 shows a grooming OLT scenario. In this case, the OLT takes on additional service grooming functions, typically including voice gateway and TDM circuit emulation functions. Note that these services can be provided using a 'pure OLT' and a separate voice gateway. + +![Figure I.3 – Grooming OLT scenario diagram](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +This diagram illustrates the 'Grooming OLT scenario'. On the left, multiple UNI(s) are connected to a CPE. The CPE is connected to an ONU. The ONU is connected to an ODN (Optical Distribution Network), represented by an oval. The ODN is connected to an OLT (Optical Line Terminal). The OLT has several output interfaces: 'Ethernet', 'SNI', 'DS1', and a label 'G.987.1(10)\_Fi-3'. + +Figure I.3 – Grooming OLT scenario diagram + +**Figure I.3 – Grooming OLT scenario** + +### **I.2.2 ONU variants** + +Figure I.4 shows the 'VDSL/POTS ONU' variant. The distinguishing feature of this variation is that the ONU is used to create copper-based interfaces just like a digital loop carrier/digital subscriber line access multiplexer (DLC/DSLAM) would do. There are two sub-types of this scheme. The first is where the ONU provides both POTS and VDSL interfaces to the customer, trying to centralize functions and reduce the need for CPE. The second is where the ONU provides VDSL-only interfaces, trying to minimize the ONU's size and power, albeit at the cost of requiring POTS derivation at the CPE. This alternative is useful mostly in FTTB and FTTC applications. + +![Figure I.4 – VDSL/POTS ONU scenario diagram](9f9386d5b3d6cbeb1ed104a799320ebf_img.jpg) + +This diagram illustrates the 'VDSL/POTS ONU scenario'. On the left, there are two CPEs. The top CPE is connected to the ONU via a 'POTS' interface and has a 'UNI(s)' input. The bottom CPE is connected to the ONU via a 'DSL' interface and also has a 'UNI(s)' input. The ONU is connected to an ODN (oval), which is connected to an OLT. The OLT has an 'SNI(s)' output and a label 'G.987.1(10)\_Fi-4'. + +Figure I.4 – VDSL/POTS ONU scenario diagram + +**Figure I.4 – VDSL/POTS ONU scenario** + +Figure I.5 shows the 'XG-PON Modem' variant, where the ONU is made as small and simple as possible. In this case, it resembles a modem that provides layer 1 and 2 interworking between the XG-PON optical interface and the data link technology. The data link then carries all service flows to the CPE, which does the bulk of the service interworking function. The popular data link technologies in use today are Cat5-based Ethernet, HPNA-over-Coax, and MoCA. This system is mostly used in FTTH applications. + +![Figure I.5 – XG-PON modem scenario diagram](94fd137860c16c8dfd75512f10161fe8_img.jpg) + +This diagram illustrates the 'XG-PON modem scenario'. On the left, a CPE labeled 'RG' has a 'UNI(s)' input. It is connected to an ONU via a 'Data link' interface. The ONU is connected to an ODN (oval), which is connected to an OLT. The OLT has an 'SNI(s)' output and a label 'G.987.1(10)\_Fi-5'. + +Figure I.5 – XG-PON modem scenario diagram + +**Figure I.5 – XG-PON modem scenario** + +Figure I.6 shows the 'integrated ONU' situation. This can be thought of as the merger of the XG-PON modem and the service-deriving CPE in the previous diagram. However, this merging of functions has critical implications on what system is responsible for the management of the services. It should also be noted that even though significant functions have been incorporated into the ONU, a CPE is typically still placed in the home. This scenario is also popular for FTTH. + +![Figure I.6 – Integrated ONU scenario. This diagram shows a network architecture where a CPE (Customer Premises Equipment) is connected to an ONU (Optical Network Unit). The ONU is connected to an ODN (Optical Distribution Network), which is in turn connected to an OLT (Optical Line Terminal). The OLT is connected to multiple SNI(s) (Service Network Interfaces). The CPE is connected to the ONU via a UNI(s) (User Network Interface). The diagram is labeled G.987.1(10)_FI-6.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +Figure I.6 – Integrated ONU scenario. This diagram shows a network architecture where a CPE (Customer Premises Equipment) is connected to an ONU (Optical Network Unit). The ONU is connected to an ODN (Optical Distribution Network), which is in turn connected to an OLT (Optical Line Terminal). The OLT is connected to multiple SNI(s) (Service Network Interfaces). The CPE is connected to the ONU via a UNI(s) (User Network Interface). The diagram is labeled G.987.1(10)\_FI-6. + +**Figure I.6 – Integrated ONU scenario** + +Figure I.7 shows the 'Residential gateway ONU' situation. This can be thought of as the merger of the integrated ONU and the service-deriving CPE in the previous diagram. This draws layer 3 functionalities into the ONU, including such items as routing, NAT, and firewall functionality. This scenario is also popular for FTTH. + +![Figure I.7 – Residential gateway ONU scenario. This diagram shows a network architecture where the CPE functionality is integrated into the ONU. The ONU is connected to an ODN, which is connected to an OLT. The OLT is connected to multiple SNI(s). The ONU is connected to the ODN via a UNI(s). The diagram is labeled G.987.1(10)_FI-7.](b5335262987c819d7f71ce40f99cb71b_img.jpg) + +Figure I.7 – Residential gateway ONU scenario. This diagram shows a network architecture where the CPE functionality is integrated into the ONU. The ONU is connected to an ODN, which is connected to an OLT. The OLT is connected to multiple SNI(s). The ONU is connected to the ODN via a UNI(s). The diagram is labeled G.987.1(10)\_FI-7. + +**Figure I.7 – Residential gateway ONU scenario** + +## I.3 Service protocol stacks + +This clause describes a list of protocol stacks for the important service traces in XG-PON systems. By service, we mean the basic layer 2-3 interfaces that have major impact on XG-PON equipment. Many high-layer services can ride on top of these interfaces; however, they tend not to have such a concrete impact on the XG-PON equipment, or at least, not an impact any different than any other access system. + +#### I.3.1 Common functions + +The common XG-PON layers are shown in Figure I.8. [ITU-T G.987.2] specifies the XG-PON physical medium and the physical media dependent layer (optics). [ITU-T G.987.3] defines the transmission convergence layer, which deals primarily with the construction of the transmission frame, and the encapsulation of payload datagrams inside XG-PON encapsulation method (XGEM) fragments. There is a wealth of other auxiliary features described in [ITU-T G.987.3], including the PLOAM channel, dynamic bandwidth allocation, and the PON-level QoS frameworks that are possible. + +It should be noted that the DBA algorithm is not specified in any standard, but this is not an interoperability issue, and the non-specification has been intentional. + +The QoS system in the XG-PON defines a scheme where each ONU may contain one or more transmission containers (T-CONTs). Each T-CONT may contain one or more XGEM Ports, which are the smallest connection entity that XG-PON systems handle. Similar to [ITU-T G.984.3], [ITU-T G.987.3] may leave the arrangement of T-CONT and GEM Ports open for the flexibility. It is expected that a similar arrangement as the current mainstream arrangement of the four service-bearing T-CONTs per ONT per service category, with each T-CONT representing a different class of service will be followed. + +[ITU-T G.988] defines the ONU management and configuration interface (OMCI). It defines both a management information base (MIB) for all the functions controlled in the ONU, as well as the ONU management communication channel (OMCC) that provides all the mechanisms required for the OLT to provide FCAPS functionality for the ONU. + +The OLT management is a somewhat more complex object. It contains by proxy all the MIBs of all the ONUs supported by that OLT, as well as all the other MIBs that describe the other functions in the OLT. This MIB is defined by several standards groups, including the Internet Engineering Task Force (IETF) and the Tele-management forum (TMF). Typically, these MIBs are accessed using standard IETF defined protocols (SNMP over TCP/IP). Most OLTs provide a dedicated interface for this management traffic. + +All of the functions mentioned above are common functions involved in all of the service traces that follow. They will be more compactly represented in the later diagrams for the sake of brevity. + +![Diagram of XG-PON common functions showing the hierarchy of management and data planes.](cfb98c691c1af5befe32ff9442eea511_img.jpg) + +The diagram illustrates the common functions of an XG-PON system, organized into three main vertical paths representing different management and data planes: + +- Left Path (ITU-T G.988 Management):** ONU MIB → OMCC → QoS → TC → PMD. This path is associated with the ITU-T G.988 standard. +- Middle Path (Data Plane):** OLT MIB → OMCC → DBA → TC → PMD. This path leads to the PON medium and is associated with ITU-T G.987.2 and ITU-T G.987.3 standards. +- Right Path (SNMP Management):** OLT MIB → SNMP → TCP/IP → Eth. MAC → Eth. PMD. This path is associated with TMF, IETF, and IEEE 802.3 standards. + +The diagram is labeled G.987.1(16)\_FI.8. + +Diagram of XG-PON common functions showing the hierarchy of management and data planes. + +**Figure I.8 – XG-PON common functions** + +The XG-PON real-time management clock service is shown in Figure I.9. The OLT receives real-time clock data (typically using NTP, over an Ethernet interface via UDP over IP). The OLT thereby maintains its own internal RTC, which it uses to time-stamp all manner of event data. Other methods of establishing the OLT RTC are possible, see Figure I.11. + +The ONU does not extend this RTC for the purposes of management. Rather, its performance monitoring and event collection processes are synchronized with those of the OLT via the OMCI. The OLT routinely collects all of this data every 15 minutes, and logs it with the OLT RTC. + +![Diagram of Real-time management clock service architecture showing OLT RTC, ONU MIB, OMCC, TC, PMD, PON medium, NTP, UDP/IP, Eth. MAC, and Eth. PMD components and their relationships.](f9c64800d9bace9b4315646d1057be3c_img.jpg) + +The diagram illustrates the real-time management clock service architecture. At the top, an OLT RTC (Real-Time Clock) is connected to a central OMCC (Optical Management Communication Controller). To the left, an ONU MIB (Management Information Base) is connected to an ONU-side OMCC. This ONU-side OMCC is part of a stack defined by ITU-T G.988, which also includes a TC (Transmission Convergence) layer and a PMD (Physical Medium Data) layer. The TC layer is part of a stack defined by ITU-T G.987.3, and the PMD layer is part of a stack defined by ITU-T G.987.2. Both ONU and OLT PMD layers connect to a common PON medium. On the right, the OLT RTC is also connected to an NTP (Network Time Protocol) server. The NTP server is part of a stack defined by IETF, which includes UDP/IP. Below the IETF stack, the OLT RTC connects to an Eth. MAC (Ethernet MAC) layer, which is part of a stack defined by IEEE 802.3. The Eth. MAC layer connects to an Eth. PMD (Ethernet Physical Medium Data) layer, which is also part of the IEEE 802.3 stack. The Eth. PMD layer is connected to the PON medium. + +Diagram of Real-time management clock service architecture showing OLT RTC, ONU MIB, OMCC, TC, PMD, PON medium, NTP, UDP/IP, Eth. MAC, and Eth. PMD components and their relationships. + +G.987.1(16)\_FI.9 + +**Figure I.9 – Real-time management clock service** + +The XG-PON network clock scheme for passing frequency synchronization to ONU is shown in Figure I.10. The OLT needs to obtain a high quality traceable timing clock, which serves as the master for all XG-PON interface timing. The normal source for the OLT's clock is a BITS timing input. However, in cases where a BITS source is not available, then an alternative method is needed. The alternative could be synchronous line timing from an SNI that is traceable to the network clock, or a packet-based timing. + +Once the OLT network clock is established, it is used to source timing to the XG-PON interfaces, which in turn distribute timing to the counterpart ONU XG-PON interfaces. The ONU equipment then obtains its network clock from the XG-PON interface. This timing signal is ideal for TDM service interworking functions that are integrated into the ONU. Typically, this timing signal is not available at UNI. However, if the timing signal is provided to the terminal adapters, then among many synchronization methods, the synchronous Ethernet method provides more precise synchronization. + +![Figure I.10: Example of network clock service. This diagram shows the network clock service architecture. At the top, an 'OLT network clock' block is connected to a 'BITS timing' input. Below it, a stack of protocol layers is shown: 'Pkt timing' (ITU-T G.8261), 'UDP/IP' (IETF), 'Eth. MAC' (IEEE 802.3), and 'Eth. PMD'. To the right, a 'DS-1 framer' (e.g., ATIS 0600107) and 'DS-1 Phy' are shown. On the left, an 'ONU network clock' is connected to a 'TC' (ITU-T G.987.3) block, which is part of a stack including 'PMD' (ITU-T G.987.2) and 'PON medium'. Arrows indicate the flow of clock information from the OLT network clock through the protocol layers and TC blocks to the ONU network clock.](e451401f8fa77b466f401d5fce15b26c_img.jpg) + +Figure I.10: Example of network clock service. This diagram shows the network clock service architecture. At the top, an 'OLT network clock' block is connected to a 'BITS timing' input. Below it, a stack of protocol layers is shown: 'Pkt timing' (ITU-T G.8261), 'UDP/IP' (IETF), 'Eth. MAC' (IEEE 802.3), and 'Eth. PMD'. To the right, a 'DS-1 framer' (e.g., ATIS 0600107) and 'DS-1 Phy' are shown. On the left, an 'ONU network clock' is connected to a 'TC' (ITU-T G.987.3) block, which is part of a stack including 'PMD' (ITU-T G.987.2) and 'PON medium'. Arrows indicate the flow of clock information from the OLT network clock through the protocol layers and TC blocks to the ONU network clock. + +G.987.1(10)\_FI-10 + +**Figure I.10 – Example of network clock service** + +For applications where the ONU requires a very accurate real-time clock with phase errors in the nanoseconds range, the following precision real-time clock is defined. The OLT obtains a precise real-time clock, typically using [IEEE 1588], optionally with some additional assistance of the previously mentioned network clock service. The OLT then passes this clocking information to the ONUs using a combination of the TC layer and the OMCI layer. The ONU can then calculate the precise time, and establish its precision RTC. If the ONU must pass the precision RTC on to client equipment, it can support the [IEEE 1588] protocol towards the UNI side. + +![Figure I.11: Precision real-time clock service. This diagram illustrates the precision real-time clock service. It shows an 'ONU precision RTC' and an 'OLT precision RTC' at the top. The OLT precision RTC is connected to an 'IEEE 1588' block, which is connected to an 'Eth. MAC' (IEEE 802.3) and 'Eth. PMD' stack. The ONU precision RTC is connected to an 'IEEE 1588' block, which is connected to an 'OMCC' (ITU-T G.988) block. The OMCC block is connected to a 'TC' (ITU-T G.987.3) block, which is part of a stack including 'PMD' (ITU-T G.987.2) and 'PON medium'. Arrows show the flow of precision clock information from the OLT precision RTC through the IEEE 1588, OMCC, TC, and PMD layers to the ONU precision RTC.](1cac1845cf99a3f64ae00cd2bb4f9ed7_img.jpg) + +Figure I.11: Precision real-time clock service. This diagram illustrates the precision real-time clock service. It shows an 'ONU precision RTC' and an 'OLT precision RTC' at the top. The OLT precision RTC is connected to an 'IEEE 1588' block, which is connected to an 'Eth. MAC' (IEEE 802.3) and 'Eth. PMD' stack. The ONU precision RTC is connected to an 'IEEE 1588' block, which is connected to an 'OMCC' (ITU-T G.988) block. The OMCC block is connected to a 'TC' (ITU-T G.987.3) block, which is part of a stack including 'PMD' (ITU-T G.987.2) and 'PON medium'. Arrows show the flow of precision clock information from the OLT precision RTC through the IEEE 1588, OMCC, TC, and PMD layers to the ONU precision RTC. + +G.987.1(16)\_FI-11 + +**Figure I.11 – Precision real-time clock service** + +#### I.3.2 Data functions + +The layer shown for Ethernet service is shown in Figure I.12. In the ONU, Ethernet frames as defined in [b-IEEE 802.3] are extracted from the TC layer. In some ONUs, the Ethernet layer is quite abbreviated, and little processing is done on the frames from their reception on the XG-PON interface to their transmission on the UNI. In other ONUs, true bridging is performed, with MAC address processing, and potentially more. In some cases, PPPoE (not shown) is supported; however, this scheme seems to be waning. + +OLT and ONU share the responsibility of access node VLAN requirement defined in Broadband Forum document [b-DSLF TR-101]. To enhance the interoperability of G-PON, [DSLF TR-156] further provides the guideline on specific VLAN operations at G-PON OLT and at ONU for 1:1, N:1, and VBES services defined in [b-DSLF TR-101]. In general, this guideline should be applied to XG-PON as well. + +For N:1 service, ONU adds an S-tag to upstream un-tagged frame, or translate the customer Q-tag to an S-tag, then OLT will pass through the S-tagged frame to the upstream. + +For 1:1 service, ONU always adds a tag to untagged frames or translates an incoming Q-tag in the upstream direction. In the case of single tagged VLAN at the V interface, OLT will pass through the S-tag added by ONU to the upstream. In the case of double tagged VLAN at the V interface, the OLT adds an S-tag on the top of the C-tag that the ONU provided. + +For the VBES service, the U interface can be untagged, single tagged, or double tagged. For the untagged or single tagged frame, the ONU adds the S-tag, and the OLT passes through the tag just like in the N:1 model. For the case in which customer frames are double tagged, the frames with valid S-tags are accepted and may be translated to a new S-tag at ONU, and then passed through the OLT. + +The traffic leaves the OLT going into the network over some type of Ethernet interface, for connection to an edge routing device or other Ethernet aggregation devices. + +It should be noted that there are several different interfaces that can take the place of an Ethernet Physical interface. These include xDSL (e.g., see below), MoCA, HPNA, HPNA-over-Coax, 802.11 Wi-Fi, and perhaps others yet to be devised. However, due to Ethernet's pervasive nature, all of these alternative PHYs are defined so that they operate nearly the same as Ethernet, and so their impact on the XG-PON system is rather small. + +All of these ONU features are controlled via the OMCI, as defined in [ITU-T G.988]. + +![Figure I.12 – Ethernet data service diagram showing the protocol stack for an ONU and an OLT connected via a PON medium.](9ff1b32449ea068bba9647d71904bd59_img.jpg) + +The diagram illustrates the Ethernet data service protocol stack, divided into two main sections: the ONU (Optical Network Unit) on the left and the OLT (Optical Line Terminal) on the right, connected via a PON medium at the bottom. + +- ITU-T G.988 (mgt)** (Management plane) is shown at the top, spanning both ONU and OLT. +- IEEE 802.1** (VLAN tagging) is shown in the upper part of the stack for both units. +- BBF TR-156** is indicated between the VLAN tagging and MAC layers. +- IEEE 802.3** (Ethernet MAC and PMD) layers are shown in the middle and lower parts of the stack. +- ITU-T G.987.3** (TC - Transport Convergence) and **ITU-T G.987.2** (PMD - Physical Medium Dependent) layers are shown in the center, connecting the ONU and OLT. +- The **PON medium** is at the very bottom, connecting the two PMD layers. + +On the ONU side (left), the stack consists of VLAN tagging, Eth. MAC, and Eth. PMD. On the OLT side (right), the stack consists of VLAN tagging/switching, Eth. MAC, TC, PMD, and PON medium. The diagram is labeled G.987.1(16)\_FI.12 in the bottom right corner. + +Figure I.12 – Ethernet data service diagram showing the protocol stack for an ONU and an OLT connected via a PON medium. + +Figure I.12 – Ethernet data service + +The VDSL2 service is shown in Figure I.13. The first thing to be said is that the DSL type that is most relevant for XG-PON is VDSL2 (defined in the [b-ITU-T G.993.x] series of Recommendations), using packet transport mode. It is possible that ADSL2+ or VDSL1 might be implemented for compatibility reasons; however, it will not be the main thrust of most XG-PON development. With this said, the VDSL2 VTU-O function in the ONU operates as an Ethernet PHY, and most of the layer diagram is similar to that of an Ethernet service. There are important differences, the biggest of which is the presence of multiple bearer channels in the same port. Each of these bearers would be treated as a 'virtual PHY', and the overall system is still unchanged. + +The management of the VTU-O located in the ONU is described in [ITU-T G.988]. + +![Figure I.13 – VDSL2 service. A layered diagram showing the protocol stack for VDSL2 service over XG-PON. The diagram is divided into two main vertical paths. The left path represents the VDSL2 service, starting with 'ITU-T G.988 (mgt)' at the top, followed by 'VLAN tagging' (IEEE 802.1), two 'Eth. MAC' (IEEE 802.3) blocks, and a 'VDSL2' (ITU-T G.993) block. The right path represents the XG-PON service, starting with 'IETF, TMF (mgt)' at the top, followed by 'VLAN tagging/switching' (IEEE 802.1), two 'Eth. MAC' (IEEE 802.3) blocks, and an 'Eth. PMD' block. Both paths converge to a common 'PON medium' at the bottom, which is connected via 'PMD' and 'TC' (ITU-T G.987.3) blocks. The 'BBF TR-156' standard is indicated in the center. The diagram also includes dashed boxes for 'ITU-T G.987.2' and 'ITU-T G.988 (mgt)'.](02bb4edc0dbdf4f0749ffd3e0ea2805c_img.jpg) + +Figure I.13 – VDSL2 service. A layered diagram showing the protocol stack for VDSL2 service over XG-PON. The diagram is divided into two main vertical paths. The left path represents the VDSL2 service, starting with 'ITU-T G.988 (mgt)' at the top, followed by 'VLAN tagging' (IEEE 802.1), two 'Eth. MAC' (IEEE 802.3) blocks, and a 'VDSL2' (ITU-T G.993) block. The right path represents the XG-PON service, starting with 'IETF, TMF (mgt)' at the top, followed by 'VLAN tagging/switching' (IEEE 802.1), two 'Eth. MAC' (IEEE 802.3) blocks, and an 'Eth. PMD' block. Both paths converge to a common 'PON medium' at the bottom, which is connected via 'PMD' and 'TC' (ITU-T G.987.3) blocks. The 'BBF TR-156' standard is indicated in the center. The diagram also includes dashed boxes for 'ITU-T G.987.2' and 'ITU-T G.988 (mgt)'. + +Figure I.13 – VDSL2 service + +Figure I.14 describes the multicast service. This is really a logical service, usually provided in conjunction with an Ethernet UNI (or similar). However, it has impact on the XG-PON system, so it is included here. The multicasting interactive signalling is provided by the [IETF IGMP], versions 2 or 3 for IPv4, and MLDv2 for IPv6. This IP-layer multicasting topology is typically translated into Ethernet-layer multicasting via the trivial mapping defined in the IEEE 802.1 standards. The management of multicasting, including the eligibility of UNIs to receive multicast traffic, the XG-PON ports that contain the multicast traffic and their interconnection are defined in [ITU-T G.988]. + +![Figure I.14 – Multicast service diagram showing the protocol stack for multicast traffic in an XG-PON system. The diagram is split into two main vertical paths. The left path is labeled 'ITU-T G.988 (mgt)' and the right path is labeled 'IETF, TMF (mgt)'. Both paths start with 'Multicasting' blocks. Between these blocks is the text 'IGMPv2/3, MLDv2'. Below the multicasting blocks are 'Eth. MAC' blocks, which are connected to 'Eth. PMD' blocks. These are enclosed in a dashed orange box labeled 'IEEE 802.3'. Above the multicasting blocks are 'IEEE 802.1' labels. The 'Eth. PMD' blocks connect to 'TC' (Traffic Control) blocks, which are connected to 'PMD' blocks. These 'TC' and 'PMD' blocks are enclosed in a dashed blue box labeled 'ITU-T G.987.3'. Below these are 'ITU-T G.987.2' blocks, which connect to the 'PON medium' at the bottom. The entire central section is enclosed in a dashed blue box labeled 'ITU-T G.987.2'. A dashed green box labeled 'IEEE 802.1' is at the top, enclosing the multicasting blocks.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +Figure I.14 – Multicast service diagram showing the protocol stack for multicast traffic in an XG-PON system. The diagram is split into two main vertical paths. The left path is labeled 'ITU-T G.988 (mgt)' and the right path is labeled 'IETF, TMF (mgt)'. Both paths start with 'Multicasting' blocks. Between these blocks is the text 'IGMPv2/3, MLDv2'. Below the multicasting blocks are 'Eth. MAC' blocks, which are connected to 'Eth. PMD' blocks. These are enclosed in a dashed orange box labeled 'IEEE 802.3'. Above the multicasting blocks are 'IEEE 802.1' labels. The 'Eth. PMD' blocks connect to 'TC' (Traffic Control) blocks, which are connected to 'PMD' blocks. These 'TC' and 'PMD' blocks are enclosed in a dashed blue box labeled 'ITU-T G.987.3'. Below these are 'ITU-T G.987.2' blocks, which connect to the 'PON medium' at the bottom. The entire central section is enclosed in a dashed blue box labeled 'ITU-T G.987.2'. A dashed green box labeled 'IEEE 802.1' is at the top, enclosing the multicasting blocks. + +G.987.1(16)\_FI.14 + +**Figure I.14 – Multicast service** + +#### I.3.3 Voice functions + +The packet-based voice service flow is pictured in Figure I.15. By packet voice service, it is understood a voice service that does not terminate on a class 5 TDM switch but instead is transported via an IP network to its destination. The mainstream protocol system used in this scenario is SIP, running over RTP/UDP/IP, all defined in the IETF documents. This is easy to say, but because SIP-based VoIP aims to replace the class 5 switching system, it must therefore implement the sizable set of voice service features. A great deal of interoperability engineering must be done in any combination of VoIP-ONU and Softswitch. + +The voice CODECs are defined in the [b-ITU-T G.711.x], [b-ITU-T G.729.x], [b-ITU-T G.726.x], and [b-ITU-T G.723.x] series of Recommendations. It should be noted that while the majority of VoIP systems are actively exploring advanced CODECs for compression reasons, XG-PON is not concerned with this, since bandwidth is plentiful. In contrast, the codec selection here is mainly driven by interoperability with the far end of the SIP VoIP session. + +The POTS UNI is defined for the large part by national standards (e.g., European operators use [b-ETSI ETS 300 001]). However, it must be noted that POTS remains a very intricate service, and many operators have special requirements on the POTS interface, particularly on the lowest-level mechanical and electrical specifications of the metallic interface. + +From the SIP agent in the ONU, the service flow traverses a path very similar to the standard Ethernet service. The user traffic, both bearer and signalling, leaves the OLT via an Ethernet interface, usually shared with other services. + +The management of the packet voice service may be varied. [ITU-T G.988] provides a full FCAPS support of SIP VoIP. However, there are several other in-band systems that are in-play, such as [b-DSLF TR-069], IETF sipping, and various proprietary configuration servers. These in-band systems are good in that they can manage VoIP terminal adapters, especially for the in-home unit, anywhere on a network, so they have a wide reach. However, most suffer from poor practical standardization, and a lack of interactive features (such as the support of alarms and performance management). To help address this last point, even when an in-band system is used for configuration of VoIP, the OMCI can still be used to gather alarms and PM information. This is basically a mixed management system. + +![Figure I.15 – Packet voice service. A protocol stack diagram showing the layers for packet voice service. The diagram is divided into two main vertical paths. The left path represents the customer side, starting with VoIP (SIP) at the top, followed by RTP/IP, VLAN, Eth. MAC, TC, and PMD. The right path represents the network side, starting with VLAN switching, followed by two Eth. MAC layers, TC, and PMD. Both paths converge to a common PON medium at the bottom. Various standards and management protocols are indicated in colored boxes: ITU-T G.988 (mgt) in blue, IETF in black, ITU-T G.711 etc. in green, IEEE 802.1 in teal, IEEE 802.3 in orange, ITU-T G.987.3 in black, ITU-T G.987.2 in black, and e.g., ETS 300 001 in red. A label (mgt) BBF TR-69 Sipping Config Serv is in pink.](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg) + +The diagram illustrates the protocol stack for packet voice service. It shows two main vertical paths representing different network architectures that converge to a common PON medium at the bottom. + +- Left Path (Customer Side):** + - ITU-T G.988 (mgt)** (blue dashed box) contains **VoIP (SIP)**. + - (mgt) BBF TR-69 Sipping Config Serv** (pink dashed box) is associated with the VoIP layer. + - IETF** (black dashed box) contains **RTP/IP**. + - ITU-T G.711 etc.** (green dashed box) contains **Codec**. + - e.g., ETS 300 001** (red dashed box) contains **POTS** and **Cu Phy**. + - VLAN** (black dashed box) is shown below the Codec. + - IEEE 802.3** (orange dashed box) contains **Eth. MAC**. + - ITU-T G.987.3** (black dashed box) contains **TC**. + - ITU-T G.987.2** (black dashed box) contains **PMD**. +- Right Path (Network Side):** + - IETF, TMF (mgt)** (blue dashed box) contains **VLAN switching**. + - IEEE 802.1** (teal dashed box) is associated with the VLAN switching layer. + - IEEE 802.3** (orange dashed box) contains two **Eth. MAC** layers and an **Eth. PMD**. + - ITU-T G.987.3** (black dashed box) contains **TC**. + - ITU-T G.987.2** (black dashed box) contains **PMD**. +- Common Bottom:** Both paths converge to a **PON medium** at the bottom, which is part of the **ITU-T G.987.2** standard. + +G.987.1(16)\_FI.15 + +Figure I.15 – Packet voice service. A protocol stack diagram showing the layers for packet voice service. The diagram is divided into two main vertical paths. The left path represents the customer side, starting with VoIP (SIP) at the top, followed by RTP/IP, VLAN, Eth. MAC, TC, and PMD. The right path represents the network side, starting with VLAN switching, followed by two Eth. MAC layers, TC, and PMD. Both paths converge to a common PON medium at the bottom. Various standards and management protocols are indicated in colored boxes: ITU-T G.988 (mgt) in blue, IETF in black, ITU-T G.711 etc. in green, IEEE 802.1 in teal, IEEE 802.3 in orange, ITU-T G.987.3 in black, ITU-T G.987.2 in black, and e.g., ETS 300 001 in red. A label (mgt) BBF TR-69 Sipping Config Serv is in pink. + +**Figure I.15 – Packet voice service** + +The protocol stack diagram for the circuit-switched voice service is shown in Figure I.16. In this scenario, VoIP is being used to transport the voice signals from the ONU to the class 5 TDM switch in the central office, and no further. The protocol used in this case is usually ITU-T H.248, since this system is suited to voice gateway interfaces, of which the ONU and OLT or possibly an aggregated uplink node each has one. + +At the ONU, from the codec and below, the arrangement is exactly the same as in the packet voice case. + +At the OLT or possibly an aggregated uplink node, the ITU-T H.248 flow is terminated, usually in a special purpose voice gateway module. This module's function is to regenerate the customer's voice interface, and format the data representing that interface in the way that a conventional DLC system would, as defined by the appropriate regional standard (e.g., V5.2). This interface, most commonly carried physically by DS1 or E1 interfaces, can then be tied directly into a class 5 switch with integrated DLC interfaces. The whole intent is to minimize the impact of the XG-PON deployment on the normal operation of voice services in the central office. + +The management of this kind of VoIP also has the potential for standard overlap, since all the options are available for ITU-T H.248 ONUs. However, the OMCI method is used quite often in this case, since the advantages of the in-band system all but disappear for this scenario. The OMCI is a self-contained solution for the management of voice services on XG-PON, and seems an easy choice in this scenario. + +There are additional combinations of transport protocols, functional architectures, and management protocols possible. The intent of the two illustrations here is to highlight the most active combinations. + +![Figure I.16 – Circuit-switched voice service. This diagram illustrates the protocol stack for circuit-switched voice services over a PON medium. It is divided into two main management domains: ITU-T G.988 (mgt) on the left and IETF, TMF (mgt) on the right. Both domains start with VoIP at the top, which connects to RTP/IP. The RTP/IP layer connects to a VLAN layer. The VLAN layer is part of the IEEE 802.1 standard. Below the VLAN layer is the Eth. MAC layer, which is part of the IEEE 802.3 standard. The Eth. MAC layer connects to a TC (Traffic Control) layer, which is part of the ITU-T G.987.3 standard. The TC layer connects to a PMD (Physical Medium Data) layer, which is part of the ITU-T G.987.2 standard. The PMD layer connects to the PON medium. On the left side, the VLAN layer also connects to a Codec, which is part of the ITU-T G.711 etc. standard. The Codec connects to a POTS (Plain Old Telephone Service) layer, which is part of the e.g., ETS 300 001 standard. The POTS layer connects to a Cu Phy (Copper Physical) layer. On the right side, the VLAN layer also connects to a Codec, which is part of the ITU-T G.711 etc. standard. The Codec connects to a GR-303 layer, which is part of the e.g., ITU-T V5.2 standard. The GR-303 layer connects to a DS-1 (Digital Signal 1) layer. The diagram also shows the ITU-T H.248 standard connecting the VoIP layers in both domains. The entire stack is supported by the PON medium at the bottom.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +Figure I.16 – Circuit-switched voice service. This diagram illustrates the protocol stack for circuit-switched voice services over a PON medium. It is divided into two main management domains: ITU-T G.988 (mgt) on the left and IETF, TMF (mgt) on the right. Both domains start with VoIP at the top, which connects to RTP/IP. The RTP/IP layer connects to a VLAN layer. The VLAN layer is part of the IEEE 802.1 standard. Below the VLAN layer is the Eth. MAC layer, which is part of the IEEE 802.3 standard. The Eth. MAC layer connects to a TC (Traffic Control) layer, which is part of the ITU-T G.987.3 standard. The TC layer connects to a PMD (Physical Medium Data) layer, which is part of the ITU-T G.987.2 standard. The PMD layer connects to the PON medium. On the left side, the VLAN layer also connects to a Codec, which is part of the ITU-T G.711 etc. standard. The Codec connects to a POTS (Plain Old Telephone Service) layer, which is part of the e.g., ETS 300 001 standard. The POTS layer connects to a Cu Phy (Copper Physical) layer. On the right side, the VLAN layer also connects to a Codec, which is part of the ITU-T G.711 etc. standard. The Codec connects to a GR-303 layer, which is part of the e.g., ITU-T V5.2 standard. The GR-303 layer connects to a DS-1 (Digital Signal 1) layer. The diagram also shows the ITU-T H.248 standard connecting the VoIP layers in both domains. The entire stack is supported by the PON medium at the bottom. + +G.987.1(16)\_FI.16 + +**Figure I.16 – Circuit-switched voice service** + +#### I.3.4 Circuit emulation functions + +TDM interfaces can also be supported over packet transport on XG-PON, as shown in Figure I.17 and Figure I.18 (note the DS-1/E1 framer would not be required for a transparent T1/E1 service). There are several options that can be exercised here. The first involves the transport of the actual TDM payload, using either a variant of the [IETF PWE3] system of protocols, or the Metro Ethernet forum's MEF-8 protocol. The second involves the use of a local OLT TDM interface, or the use of a packet interface on the OLT leading to a gateway somewhere else in the network. This would seem to present quite a large set of alternatives, but in practice it has turned out not to be a big issue because most hardware supports nearly all of the options. So, interoperability is mostly a matter of negotiating the transport protocol. Circuit emulation may also require a network clock to be delivered to the PWE3 interworking functions. Differential timing mode supports better jitter/wander performance than adaptive mode. + +The XG-PON core, up to and including the VLAN layer is similar to the typical Ethernet service. + +The actual TDM interfaces are defined in, for example, [ITU-T G.703] for DS1 and E1 interfaces, or the appropriate regional standard (e.g., [b-ATIS 0600107] for DS1 interfaces, and [b-ETSI ETS 300 166] for E1 interfaces). + +The management of either PWE3 or MEF-8 interworking is described in [ITU-T G.988]. + +![Figure I.17: Packet TDM service using PWE3 and grooming OLT. This diagram shows two parallel service paths over a common PON medium. The left path is managed by ITU-T G.988 (mgt) and uses PWE3, RTP/IP, VLAN, Eth. MAC, TC, and PMD layers. It connects to an external network (e.g., ATIS 0600107) via DS-1 framer and DS-1 Phy. The right path is managed by IETF, TMF (mgt) and also uses PWE3, RTP/IP, VLAN, Eth. MAC, TC, and PMD layers, connecting to the same external network. The central part of the diagram shows the layers defined by standards: IETF (PWE3, RTP/IP), IEEE 802.1 (VLAN), IEEE 802.3 (Eth. MAC), ITU-T G.987.3 (TC), ITU-T G.987.2 (PMD), and the PON medium.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +Figure I.17: Packet TDM service using PWE3 and grooming OLT. This diagram shows two parallel service paths over a common PON medium. The left path is managed by ITU-T G.988 (mgt) and uses PWE3, RTP/IP, VLAN, Eth. MAC, TC, and PMD layers. It connects to an external network (e.g., ATIS 0600107) via DS-1 framer and DS-1 Phy. The right path is managed by IETF, TMF (mgt) and also uses PWE3, RTP/IP, VLAN, Eth. MAC, TC, and PMD layers, connecting to the same external network. The central part of the diagram shows the layers defined by standards: IETF (PWE3, RTP/IP), IEEE 802.1 (VLAN), IEEE 802.3 (Eth. MAC), ITU-T G.987.3 (TC), ITU-T G.987.2 (PMD), and the PON medium. + +G.987.1(16)\_FI.17 + +Figure I.17 – Packet TDM service using PWE3 and grooming OLT + +![Figure I.18: Packet TDM service using MEF-8 and pure OLT. This diagram shows two parallel service paths over a common PON medium. The left path is managed by ITU-T G.988 (mgt) and uses MEF-8, VLAN, Eth. MAC, TC, and PMD layers. It connects to an external network (e.g., ETS 300 166) via E1 framer and E1 Phy. The right path is managed by IETF, TMF (mgt) and uses VLAN, Eth. MAC, TC, and PMD layers, connecting to the same external network. The central part of the diagram shows the layers defined by standards: MEF (MEF-8), IEEE 802.1 (VLAN), IEEE 802.3 (Eth. MAC), ITU-T G.987.3 (TC), ITU-T G.987.2 (PMD), and the PON medium.](9252ccfbbe9e34cb108f0060f2b563f1_img.jpg) + +Figure I.18: Packet TDM service using MEF-8 and pure OLT. This diagram shows two parallel service paths over a common PON medium. The left path is managed by ITU-T G.988 (mgt) and uses MEF-8, VLAN, Eth. MAC, TC, and PMD layers. It connects to an external network (e.g., ETS 300 166) via E1 framer and E1 Phy. The right path is managed by IETF, TMF (mgt) and uses VLAN, Eth. MAC, TC, and PMD layers, connecting to the same external network. The central part of the diagram shows the layers defined by standards: MEF (MEF-8), IEEE 802.1 (VLAN), IEEE 802.3 (Eth. MAC), ITU-T G.987.3 (TC), ITU-T G.987.2 (PMD), and the PON medium. + +G.987.1(16)\_FI.18 + +Figure I.18 – Packet TDM service using MEF-8 and pure OLT + +#### I.3.5 Video overlay functions + +Figure I.19 shows the video overlay service. This is carried on the PON using a third wavelength, and is practically distinct from the other services. The signal format delivered to the customer is defined by SCTE standards, and the management of the ONU interface is given by [ITU-T G.988]. The optical interfaces throughout the rest of the service path are generally defined by [ITU-T J.186]. In practice, the details of the video OLT and subtending optical amplifiers are left to network operator engineering, especially the signal levels at each point in the network. This is due to the large variations in network physical topology and channel plans. + +![Diagram of the video overlay service architecture showing the flow from ANSI/SCTE-40 through PMD, ITU-T J.186, EDFA, and Tx to the PON medium.](834fb96b114b8fdc001625e1ae28e8b1_img.jpg) + +The diagram illustrates the video overlay service architecture. It shows a signal flow from left to right. On the far left, a green dashed box labeled 'ANSI/SCTE-40' is connected to a white rectangular block labeled 'PMD'. The 'PMD' block is part of a larger system enclosed in a blue dashed box labeled 'ITU-T G.988 (mgt)'. The 'PMD' connects to a central white rectangular block labeled 'ITU-T J.186'. This 'ITU-T J.186' block is connected to another white rectangular block labeled 'EDFA'. The 'EDFA' is part of a system enclosed in a blue dashed box labeled 'SCTE (mgt)'. The 'EDFA' connects to a white rectangular block labeled 'Tx'. The 'Tx' block is connected to a white rectangular block labeled 'PON medium' at the bottom. The label 'G.987.1(16)\_FI.19' is located in the bottom right corner of the diagram. + +Diagram of the video overlay service architecture showing the flow from ANSI/SCTE-40 through PMD, ITU-T J.186, EDFA, and Tx to the PON medium. + +**Figure I.19 – Video overlay service** + +# Appendix II + +## Synchronizing requirements for wireless in CBU scenario + +(This appendix does not form an integral part of this Recommendation.) + +**Table II.1 – Synchronization requirements for wireless** + +| Application | Synchronization requirements | +|-------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| UMTS-FDD |
  • • Frequency accuracy for the radio interface of the base stations is \pm 50 ppb
  • • For Pico base stations, the accuracy can be relaxed to \pm 100 ppb
| +| UMTS-TDD |
  • • Frequency accuracy for the radio interface of the base stations is \pm 50 ppb
  • • For Pico base stations, the accuracy can be relaxed to \pm 100 ppb
  • • The phase alignment of neighbouring base stations must be within 2.5 \mu\text{s}
| +| CDMA2000 |
  • • Frequency accuracy for the radio interface of the base stations is \pm 50 ppb
  • • For Pico base stations, the accuracy can be relaxed to \pm 100 ppb
  • • The pilot time alignment error should be less than 3 \mu\text{s} and must be less than 10 \mu\text{s}
| +| TD-SCDMA |
  • • Frequency accuracy for the radio interface of the base stations is \pm 50 ppb
  • • For Pico base stations, the accuracy can be relaxed to \pm 100 ppb
  • • The phase alignment of neighbouring base stations must be within 3 \mu\text{s}
| + +# Appendix III + +## External access network back-up + +(This appendix does not form an integral part of this Recommendation.) + +In many applications, some resilience to faults in the optical access network is desired, but the cost of full protection is not supportable. In these cases, a cost-effective alternative is to provide a lower capacity back-up to the service via an external access network. Examples of the external access networks include fixed wireless, mobile wireless, hybrid fibre coax networks, etc. + +Because of the wide range of back-up access networks, the interface from the PON equipment to the back-up network has to be at the data frame networking layer, described in the IEEE 802.1 standards. By abstracting the interface to this layer, the PON equipment need not worry about the details of the back-up network (nor does the back-up network need to worry about the PON). + +The key aspect of such external back-up is the location and control of the back-up switching logic. Because of the widely disparate capacities of the primary PON and the back-up network, it does not make sense to send two copies of traffic at all times. Also, due to the packet-nature of the traffic, it is difficult for the receiver to resolve multiple copies of the same packets. It is assumed that the receiver will simply accept all packets arriving from either access network; therefore, it is important to only send one copy of any packet. The source side must direct the traffic to the appropriate access network, and it must have the information required to make the correct choice. In addition, the source side switching equipment must also have the ability to prioritize traffic, and selectively discard traffic that exceeds the capacity of the back-up network when back-up is in force. In the upstream, the back-up switch can be located in the ONU, or beyond the UNI. In the downstream direction, the back-up switch can be located in the OLT, or beyond the SNI. These arrangements are illustrated in Figure III.1. + +![Figure III.1 – Four switching arrangements for external access network back-up. The figure shows four diagrams (a, b, c, d) illustrating different network configurations between User Equipment, ONU, ODN, External AN, OLT, and Service node. (a) shows both back-up switches inside the ONU and OLT. (b) shows the back-up switch in the User Equipment and inside the OLT. (c) shows the back-up switch inside the ONU and outside the OLT. (d) shows the back-up switch in the User Equipment and outside the OLT.](0a42e05c07941450f34e4f7117725834_img.jpg) + +(a) + +(b) + +(c) + +(d) + +Figure III.1 – Four switching arrangements for external access network back-up. The figure shows four diagrams (a, b, c, d) illustrating different network configurations between User Equipment, ONU, ODN, External AN, OLT, and Service node. (a) shows both back-up switches inside the ONU and OLT. (b) shows the back-up switch in the User Equipment and inside the OLT. (c) shows the back-up switch inside the ONU and outside the OLT. (d) shows the back-up switch in the User Equipment and outside the OLT. + +G.987.1(16)\_FIII.1 + +**Figure III.1 – Four switching arrangements for external access network back-up** + +In option a, the switches are both located in the PON equipment. It is assumed that the PON equipment has knowledge of the PON link's operational state, and therefore it can direct traffic to the PON interface if it is working correctly and to the back-up network interface if it is not. Therefore, no additional signalling is required. The configuration of the ONU's dual ANIs must be supported in the OMCI. + +In option b, the upstream switch is located beyond the ONT's UNI. A typical situation would be for this function to be located in an Ethernet switch or IP router. Therefore, that switch must be capable of learning the status of the ONU's PON link via some form of signalling. This could be as crude as the ONU deactivating the UNI when the PON link has failed, to more sophisticated Ethernet alarm indication signal (AIS) such as the one described in [b-ITU-T Y.1731]. The downstream switch is internally controlled within the OLT. + +In option c, the downstream switch is located beyond the OLT's SNI. A typical function would be for this function to be located in an Ethernet aggregation network, or in a service edge router. Just as in option b, this switching logic must be given the information on the status of the PON link to the ONT in question. Unlike the previous case, however, a sophisticated per-ONT AIS scheme must be employed, since the SNI is shared over many ONUs, some of which may not have a PON transmission problem. This could be the AIS as described in [b-ITU-T Y.1731], but applied on a per-VLAN basis. The upstream switch is internally controlled within the ONU, with the configuration of the ONU's dual ANIs being supported in the OMCI. + +In option d, both of the switches are located beyond the PON equipment. This scheme is most distantly removed from the access networks, since all the back-up switching/routing is happening in other equipment. This raises the possibility of allowing the back-up to occur using the more autonomous schemes such as Ethernet spanning-tree or IP routing. In either case, the back-up link would need to be configured as the 'expensive link', so that it would not be used if the PON link was available. These layer 2 or 3 schemes tend to take longer than more direct schemes mentioned in the previous options a-c. Their performance could be improved by implementing the direct AIS schemes to provide a faster feedback into their control algorithms. + +# Appendix IV + +## Operation with IEEE 1588: Principles + +(This appendix does not form an integral part of this Recommendation.) + +[IEEE 1588] describes a protocol for transferring time and/or frequency through a packet network. A good explanation of this can be found in section 7 of [b-ISPCS-2008]. + +XG-PON distributes the [IEEE 1588] master and slave functionality between the OLT and the ONU. The OLT will perform the slave port function (or in the case of a shelf, the OLT will receive the frequency and time from the function in the shelf which performs the slave port function). The OLT synchronizes the PON line rate to the network clock frequency, and transfers the time of day information to the ONU using the method in [ITU-T G.987.3] clause 13.2. The ONU uses the methods specified in [ITU-T G.987.2] to recover frequency and [ITU-T G.987.3] to recover time. The ONU will then either function as a master port to subsequent nodes or output the time and frequency through another interface. + +# Appendix V + +## Operation with IEEE 1588: Use cases for frequency and time of day synchronization + +(This appendix does not form an integral part of this Recommendation.) + +There are many applications where precise time and/or frequency must be transferred through a packet network from a source to a destination. In this appendix several use cases are described, in terms of the methods used to deliver frequency and/or time. Since most of the use cases mentioned are related to mobile backhauling applications, examples will use the RNC and Node B network elements, though these use cases are not intended to be exhaustive. + +Frequency and/or time of day synchronization is provided to the OLT via either: + +- 1) Physical timing interface (e.g., synchronous Ethernet) (frequency only) +- 2) [IEEE 1588] + synchronous Ethernet +- 3) [IEEE 1588] + non- synchronous Ethernet +- 4) Physical time of day(ToD) interface + SyncE + +Frequency and/or time of day synchronization is supplied from the ONU via either: + +- 1) Physical timing interface (e.g., synchronous Ethernet) (frequency only) +- 2) [IEEE 1588] + synchronous Ethernet +- 3) [IEEE 1588] + non-synchronous Ethernet +- 4) Physical ToD interface + SyncE + +The use cases are described in terms of various combinations of these synchronization inputs and outputs as shown in Table V.1. + +**Table V.1 – XG-PON synchronization use cases** + +| Use case | Network synchronization to OLT | UNI synchronization from ONU | +|----------|--------------------------------|------------------------------| +| 1 | SyncE (frequency only) | SyncE (frequency only) | +| 2 | [IEEE 1588] and SyncE | [IEEE 1588] and SyncE | +| 3 | [IEEE 1588] | [IEEE 1588] | +| 4 | [IEEE 1588] | [IEEE 1588] and SyncE | +| 5 | [IEEE 1588] and SyncE | ToD interface and SyncE | +| 6 | [IEEE 1588] | ToD interface and SyncE | +| 7 | ToD interface and SyncE | ToD interface and SyncE | + +Figure V.1 depicts use case 1 where frequency only is transferred through the XG-PON network. The clock interface at the OLT input and the ONU output is a physical timing interface such as synchronous Ethernet (SyncE), defined in [ITU-T G.8262]. The OLT synchronizes the PON line rate to this physical interface. The ONU outputs a physical timing interface such as synchronous Ethernet which is synchronous to the PON line rate. + +![Diagram of Figure V.1: Using synchronous Ethernet in XG-PON (use case 1).](5ee1bbbf85b473f78af9ec8368a4159a_img.jpg) + +This diagram illustrates the use of synchronous Ethernet in an XG-PON network. On the left, four 'Node B' units are shown, each connected to a 'Clock slave' and an 'ONU'. Each 'Node B' is connected to its 'Clock slave' via an 'ETH' link, and to its 'ONU' via a 'SyncE' link. All four 'ONU's are connected to a central 'OLT' unit. The 'OLT' is connected to a 'Packet network' cloud via an 'ETH' link. The 'Packet network' is connected to an 'RNC' (Radio Network Controller) via an 'ETH' link. The 'RNC' is connected to a 'PRC' (Primary Reference Clock) via a 'SyncE' link. The 'OLT' also receives a 'PON CKL' signal from the 'PRC'. + +Diagram of Figure V.1: Using synchronous Ethernet in XG-PON (use case 1). + +**Figure V.1 – Using synchronous Ethernet in XG-PON (use case 1)** + +There are several use cases of interest which use [IEEE 1588] (use cases 2 through 6), with the following assumptions. The PRC provides a frequency reference. The OLT network interface is Ethernet, with the Ethernet line rate either synchronous to a network frequency reference (synchronous Ethernet) or not synchronous to a network frequency reference. The OLT obtains time of day using [IEEE 1588], usually through intervening nodes between the OLT and the PRC. The OLT synchronizes to the network frequency reference either using synchronous Ethernet, [IEEE 1588], or some other physical layer synchronous interface. The OLT transfers the time of day to the ONU using the method specified in clause 13 of [ITU-T G.987.3]. The OLT transfers the network frequency reference to the ONU via its downstream line rate, which is synchronous to the network frequency reference. The ONU user interface is Ethernet, with the Ethernet line rate either synchronous to a network frequency reference (synchronous Ethernet) or not synchronous to a network frequency reference. The ONU may also have a physical time interface (e.g., 1 pps). + +![Diagram of Figure V.2a: PTP use cases 2: ONU as IEEE 1588 master, OLT as IEEE 1588 slave with SyncE at both SNI and UNI.](3442f31a562d1ef45bfa18b18a6a1ddc_img.jpg) + +This diagram illustrates PTP use case 2. On the left, four 'Node B' units are shown, each connected to a 'Slave' and an 'ONU'. Each 'Node B' is connected to its 'Slave' via an 'ETH' link, and to its 'ONU' via a 'SyncE' link. All four 'ONU's are connected to a central 'OLT' unit. The 'OLT' is connected to a 'Packet network' cloud via an 'ETH' link. The 'Packet network' is connected to an 'RNC' via an 'ETH' link. The 'RNC' is connected to a 'Grandmaster clock' via a 'Master' link. The 'OLT' receives '1588 and SyncE' signals from the 'Grandmaster clock' through the 'Packet network'. The 'OLT' also receives '1588 and SyncE' signals from the 'RNC' through the 'Packet network'. The 'OLT' transfers '1588' signals to the 'ONU's via an 'XG-PON1' link. The 'ONU's transfer '1588' signals to the 'Node B's via an 'ETH' link. + +Diagram of Figure V.2a: PTP use cases 2: ONU as IEEE 1588 master, OLT as IEEE 1588 slave with SyncE at both SNI and UNI. + +**Figure V.2a – PTP use cases 2: ONU as IEEE 1588 master, OLT as IEEE 1588 slave with SyncE at both SNI and UNI** + +![Figure V.2b: PTP use cases 3 diagram. Four Node Bs (Slave) are connected via Ethernet (ETH) to four ONUs (Master). Each ONU is also connected to an OLT (Slave) via ITU-T G.987.3. The OLT is connected to a Packet network (Slave) via Ethernet (ETH). The Packet network is connected to an RNC (Master) via Ethernet (ETH). The RNC is connected to a Grandmaster clock (Master). Arrows indicate the flow of IEEE 1588 synchronization messages from the Grandmaster clock through the RNC, Packet network, OLT, ONUs, and finally to the Node Bs. A label 'G.987.1(16)_FV.2b' is in the bottom right.](dbd074feb5cce1300f42f91da8f673d1_img.jpg) + +Figure V.2b: PTP use cases 3 diagram. Four Node Bs (Slave) are connected via Ethernet (ETH) to four ONUs (Master). Each ONU is also connected to an OLT (Slave) via ITU-T G.987.3. The OLT is connected to a Packet network (Slave) via Ethernet (ETH). The Packet network is connected to an RNC (Master) via Ethernet (ETH). The RNC is connected to a Grandmaster clock (Master). Arrows indicate the flow of IEEE 1588 synchronization messages from the Grandmaster clock through the RNC, Packet network, OLT, ONUs, and finally to the Node Bs. A label 'G.987.1(16)\_FV.2b' is in the bottom right. + +**Figure V.2b – PTP use cases 3: ONU as IEEE 1588 master, OLT as IEEE 1588 slave without SyncE** + +![Figure V.2c: PTP use case 4 diagram. Four Node Bs (Slave) are connected via Ethernet (ETH) to four ONUs (Master). Each ONU is also connected to an OLT (Slave) via XG-PON1. The OLT is connected to a Packet network (Slave) via Ethernet (ETH). The Packet network is connected to an RNC (Master) via Ethernet (ETH). The RNC is connected to a Grandmaster clock (Master). Arrows indicate the flow of IEEE 1588 synchronization messages from the Grandmaster clock through the RNC, Packet network, OLT, ONUs, and finally to the Node Bs. Additionally, SyncE signals are shown being passed from the ONUs to the Node Bs. A label 'G.987.1(16)_FV.2c' is in the bottom right.](fe25bbee6685ab20f50ffc80c3feddd8_img.jpg) + +Figure V.2c: PTP use case 4 diagram. Four Node Bs (Slave) are connected via Ethernet (ETH) to four ONUs (Master). Each ONU is also connected to an OLT (Slave) via XG-PON1. The OLT is connected to a Packet network (Slave) via Ethernet (ETH). The Packet network is connected to an RNC (Master) via Ethernet (ETH). The RNC is connected to a Grandmaster clock (Master). Arrows indicate the flow of IEEE 1588 synchronization messages from the Grandmaster clock through the RNC, Packet network, OLT, ONUs, and finally to the Node Bs. Additionally, SyncE signals are shown being passed from the ONUs to the Node Bs. A label 'G.987.1(16)\_FV.2c' is in the bottom right. + +**Figure V.2c – PTP use case 4: ONU as IEEE 1588 master, OLT as IEEE 1588 slave, with SyncE at UNI** + +Figures V.2 (a and b) show use cases 2 and 3 for wireless backhaul. The OLT has an [IEEE 1588] slave port at the SNI, which obtains the time of day from the network. This time of day is passed to the ONU as described above, and the ONU passes the time of day from an [IEEE 1588] master port to the Node B. If the OLT network feed is synchronous Ethernet (use case 2), then the OLT will synchronize its downstream PON line rate to the synchronous Ethernet line rate; otherwise the OLT will synchronize its downstream PON line rate to the [IEEE 1588] time of day (use cases 3). If the link between the ONU and the Node B is synchronous Ethernet (use cases 2), then the synchronous Ethernet line rate will be synchronized to the downstream PON line rate. Synchronous Ethernet ESMC messages would be used in conjunction with the synchronous Ethernet to indicate clock quality. + +Figure V.3a shows use case 5, while Figure V.3b illustrates use case 6 for wireless backhaul. The only difference between Figure V.2 and Figure V.3 is that the ONU has a physical interface for transferring time to the Node B, such as a ToD interface. If the OLT network feed is synchronous Ethernet (use case 5), then the OLT will synchronize its downstream PON line rate to the synchronous + +Ethernet line rate; otherwise the OLT will synchronize its downstream PON line rate to the [IEEE 1588] time of day (use cases 6). + +Figure V.2c illustrates use case 4 where the OLT does not receive synchronous Ethernet and derives the downstream PON line rate from 1588. In this case the ESMC messages would correspond to the 1588 clock quality and not a clock quality received via ESMC at the OLT. + +Figure V.4 shows use case 7, where a physical ToD interface is provided as an input to the OLT. The OLT processes the ToD information and sends timing information to the ONU according to the description provided in clause 13.2 of [ITU-T G.987.3]. The ONU processes the received timing information and outputs the timing information using a physical ToD interface. + +NOTE – The details of the physical ToD interface are FFS. + +![Figure V.3a – PTP use case 5: ONU with physical time interface, OLT as IEEE 1588 slave with SyncE at both SNI and UNI](a387e0c81bfc615ececcd1b55dbf5de4_img.jpg) + +**Figure V.3a – PTP use case 5: ONU with physical time interface, +OLT as IEEE 1588 slave with SyncE at both SNI and UNI** + +Detailed description: A network diagram showing timing distribution. On the right, an RNC contains a Grandmaster clock (Master). It connects via ETH to a Packet network, carrying '1588 and SyncE'. The Packet network connects via ETH to an OLT (Slave), also carrying '1588 and SyncE'. The OLT connects to four ONUs via ITU-T G.987.3 links. Each ONU connects via ETH to a Node B, providing 'ToD and SyncE'. Each Node B is associated with a radio tower icon. + +Figure V.3a – PTP use case 5: ONU with physical time interface, OLT as IEEE 1588 slave with SyncE at both SNI and UNI + +![Figure V.3b – PTP use case 6: ONU with physical time interface, OLT as IEEE 1588 slave with SyncE at UNI only](4666738057044ad78ced4dbbc0c1bfb3_img.jpg) + +**Figure V.3b – PTP use case 6: ONU with physical time interface, +OLT as IEEE 1588 slave with SyncE at UNI only** + +Detailed description: This diagram is nearly identical to Figure V.3a. The key difference is the timing signal between the Packet network and the OLT (Slave) is labeled only as '1588', and the signal between the RNC and the Packet network is also labeled only as '1588'. The links from ONUs to Node Bs still carry 'ToD and SyncE'. + +Figure V.3b – PTP use case 6: ONU with physical time interface, OLT as IEEE 1588 slave with SyncE at UNI only + +46 Rec. ITU-T G.987.1 (03/2016) + +![Diagram of Use case 7 showing time synchronization flow from a Clock Master through an RNC, Packet network, OLT, and ONUs to multiple Node Bs.](4162c218fc7881cd90fc9574e07d2327_img.jpg) + +The diagram illustrates a network architecture for time synchronization. On the far right, a 'Clock Master' (represented by an oval) provides a 'Master' clock signal to an 'RNC' (Radio Network Controller, represented by a server rack). The RNC is connected to a 'Packet network' (represented by a cloud) via an 'ETH' (Ethernet) link. A red arrow labeled 'ToD and SyncE' points from the RNC into the packet network. The packet network is connected to an 'OLT' (Optical Line Terminal, represented by a blue box) via another 'ETH' link. A red arrow labeled 'ToD and SyncE' points from the packet network into the OLT. The OLT has an internal 'ITU-T G.987.3' component (represented by an oval) and a red arrow labeled 'ToD and SyncE' pointing from it. Four 'ONU' (Optical Network Unit, represented by blue boxes) units are connected to the OLT. Each ONU also contains an 'ITU-T G.987.3' component. Red arrows labeled 'ToD and SyncE' point from each ONU's internal component to a corresponding 'Node B' (represented by a yellow box). Each Node B is connected to an antenna tower. The text 'G.987.1(16)\_FV.4' is located in the bottom right corner of the diagram area. + +Diagram of Use case 7 showing time synchronization flow from a Clock Master through an RNC, Packet network, OLT, and ONUs to multiple Node Bs. + +**Figure V.4 – Use case 7, ONU and OLT with physical time interface** + +# Appendix VI + +## Operation with IEEE 1588 + +(This appendix does not form an integral part of this Recommendation.) + +## Transport of ESMC messages over PON + +In Appendix V, the use case of synchronous Ethernet over the PON was described and the Ethernet synchronization messaging channel (ESMC) was introduced. This appendix addresses frequency synchronization over XG-PON but focuses on a recommended method to transfer the SSM carried in the ESMC (as defined in [b-ITU-T G.8264]) that are used to send the synchronous Ethernet clock quality in a one-way fashion from the clock master to a base station or other end device. Refer to Figure V.1, "Using synchronous Ethernet in XG-PON" in Appendix V. + +Within the physical layer, synchronous Ethernet is transferred over the OLT/ODN/ONU in the following way. A synchronous Ethernet-capable OLT will lock the XG-PON clock to the received Ethernet clock at the OLT SNI, and a synchronous Ethernet-capable ONU will in turn lock the Ethernet clock of one or more provisioned Ethernet port UNIs ([ITU-T G.8262] defines the types of UNIs capable of Synchronous Ethernet) to the XG-PON clock. + +### Characteristics of the ESMC + +- Simple, stateless unidirectional protocol for communicating the current reference clock quality between nodes. +- Uses the [IEEE 802.3] organization specific slow protocol (OSSP). +- Destination address is the IEEE defined slow protocol multicast address. +- One message type, the synchronization status message. +- Sent at approximately one message per second containing the clock quality level (QL). + +### ESMC messages over XG-PON + +ESMC messaging must be handled by the OLT/ONU as a system. + +The main difference in how a PON must handle ESMC messages versus an Ethernet switch is that the OLT to ONU link is not a point-to-point Ethernet link but rather uses the XG-PON point to multipoint protocol, with the ESMC messages sent via GEM encapsulation. While different in this respect, in all *functional* aspects the OLT and the ONU may handle ESMC messages largely as defined in [b-ITU-T G.8264]. + +### Method for sending Synchronization Status Messages over XG-PON + +An OLT that is Synchronous Ethernet-capable should provisionally process and act upon ESMC messages that are received on Synchronous Ethernet provisioned SNI ports. + +If there are multiple provisioned Synchronous Ethernet-capable ports then the OLT should synchronize to and obtain the clock quality (QL value) from the best port using the synchronization selection methods defined in [b-ITU-T G.8264] and [b-ITU-T G.781]. + +The OLT should then send OSSP ESMC messages of equal clock quality minimizing additional impact on PON traffic. The OLT should not send ESMC messages unless it has been provisioned to do so. + +ONUs may be provisioned to recognize ESMC through the normal process of configuring an incidental broadcast GEM port, the appropriate VLAN, and a bridge to the desired Ethernet UNIs. After intercept, the ONU will have obtained the clock quality which will equal to that of the ESMC received at the OLT. The ONU should then send ESMC messages that are compliant to [b-ITU-T G.8264], only from UNIs that are members of the ESMC VLAN bridge. + +# Bibliography + +- [b-ITU-T G.671] Recommendation ITU-T G.671 (2012), *Transmission characteristics of optical components and subsystems.* +- [b-ITU-T G.711.x] Recommendation ITU-T G.711.x (in force), *Pulse code modulation (PCM) of voice frequencies.* +- [b-ITU-T G.723.x] Recommendation ITU-T G.723.x (in force), *Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s.* +- [b-ITU-T G.726.x] Recommendation ITU-T G.726.x (in force), *40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM).* +- [b-ITU-T G.729.x] Recommendation ITU-T G.729.x (in force), *Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP).* +- [b-ITU-T G.781] Recommendation ITU-T G.781 (in force), *Synchronization layer functions.* +- [b-ITU-T G.957] Recommendation ITU-T G.957 (2006), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy.* +- [b-ITU-T G.965] Recommendation ITU-T G.965 (2001), *V-interfaces at the digital local exchange (LE) – V5.2 interface (based on 2048 kbit/s) for the support of access network (AN).* +- [b-ITU-T G.993.x] Recommendation ITU-T G.933.x (in force), *Very high speed digital subscriber line transceivers .* +- [b-ITU-T G.8264] Recommendation ITU-T G.8264 (in force), *Distribution of timing information through packet networks.* +- [b-ITU-T G-Sup.45] ITU-T G-series Recommendations – Supplement 45 (2009), *GPON power conservation.* +- [b-ITU-T H.248.1] Recommendation ITU-T H.248.1 (in force), *Gateway control protocol: Version 3.* +- [b-ITU-T Q.552] Recommendation ITU-T Q.552 (2001), *Transmission characteristics at 2-wire analogue interfaces of digital exchanges.* +- [b-ITU-T Y.1731] Recommendation ITU-T G.8013/Y.1731 (2015), *OAM functions and mechanisms for Ethernet based networks.* +- [b-ATIS 0600107] ATIS 0600107.2002(S2015), *Digital Hierarchy – Formats Specifications.* +- [b-ATIS 0900102] ATIS 0900102.1993(S2015), *Digital Hierarchy – Electrical Interfaces.* +- [b-DSLF TR-069] Broadband Forum TR-069 Amendment 2 (2007), *CPE WAN Management Protocol V1.1.* +- [b-DSLF TR-101] Broadband Forum TR-101 (2006), *Migration to Ethernet Based DSL Aggregation.* +- [b-ETSI ETS 300 001] ETSI ETS 300 001 ed.4 (1997), *Attachments to the Public Switched Telephone Network (PSTN); General technical requirements for equipment connected to an analogue subscriber interface in the PSTN.* + +- [b-ETSI ETS 300 166] ETSI ETS 300 166 ed.1 (1993), *Transmission and Multiplexing (TM); Physical and electrical characteristics of hierarchical digital interfaces for equipment using the 2 048 kbit/s – based plesiochronous or synchronous digital hierarchies.* +- [b-IEEE 802.1X] IEEE 802.1X -in force, *IEEE Standard for Local and metropolitan area networks – Port-Based Network Access Control.* +- [b-IEEE 802.3] IEEE 802.3-2008, *IEEE Standard for Information Technology – Telecommunications and Information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 3 – Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications.* +- [b-ISPCS-2008] Tutorial on IEEE 1588 Version 2 by Geoffrey Garner in 2008, *International IEEE Symposium on Precision Clock Synchronization for Measurement, Control and Communication*, Ann Arbor, MI, USA. + <> + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals 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-0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:95cc92677c8cda788fdec3e2701c3b58c634f61d6cf2f1ee6df33b9d85526ffd +size 112090 diff --git a/marked/G/T-REC-G.992.4-200207-I_PDF-E/raw.md b/marked/G/T-REC-G.992.4-200207-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..5501650e9b75c3082cc2ced4c615878edb5ab5da --- /dev/null +++ b/marked/G/T-REC-G.992.4-200207-I_PDF-E/raw.md @@ -0,0 +1,667 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.992.4** + +(07/2002) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Access networks + +--- + +**Splitterless asymmetric digital subscriber line +transceivers 2 (splitterless ADSL2)** + +ITU-T Recommendation G.992.4 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2) + +## Summary + +This Recommendation describes the interface between the telecommunications network and the customer installation in terms of their interaction and electrical characteristics. G.992.4 allows the transmission of POTS and V-series data services simultaneously with a digital channel over a single mixed gauge twisted metallic pair. Operation in a TCM-ISDN noise environment is for further study. This Recommendation is structured as a delta document to ITU-T Rec. G.992.3. + +This Recommendation includes procedures to allow provisioning without the need for "splitters", typically installed at the ingress to the customer premises. Additionally, power management procedures and link states are specified to achieve power savings at the central office and customer premises. + +This Recommendation describes the second generation of splitterless ADSL, based on the first generation ITU-T Rec. G.992.2. This Recommendation may be easily implemented in multi-mode devices that support both G.992.4 and G.992.2 with the following major additions and revisions: + +- Improved application support for an all digital mode of operation and voice over ADSL operation. +- A new packet TPS-TC function and a STM TPS-TC function in addition to the existing ATM support. +- Support for IMA in the ATM TPS-TC. +- Improved configuration capability for each TPS-TC with configuration of latency, BER and minimum, maximum and reserve data rate. +- New line diagnostic procedures available for both successful and unsuccessful initialization scenarios. +- Enhanced on-line reconfiguration capabilities including bit-swaps, dynamic rate repartitioning, and seamless rate adaptation. +- A more flexible TPS-TC function including support for up to 4 frame bearers, 4 latency paths, and control parameters allowing enhanced configuration of the overhead channel. +- Performance improvements including mandatory support for $R = 16$ , one-bit constellations, and trellis coding. +- A more robust initialization procedure that includes splitterless capability features of the G.992.2 fast retrain procedure, CO and CP controlled adaptive signal durations, receiver determined adaptive frequency modulation for data exchange, and an optional adaptive length fast start-up procedure. +- Improved RFI and spectrum management tools including transmit power cutback at both ends of the line, spectrum shaping, sub-carrier black-out lists to avoid RFI, and improved sub-carrier ordering to help mitigate the propagation of RFI from sub-carrier to sub-carrier. +- Power saving features including mandatory reduction of excess margin under management layer control and a new L2 power management link state with low power features for the central office. + +## Source + +ITU-T Recommendation G.992.4 was prepared by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 29 July 2002. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2003 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +###### Page + +| | | | +|-------|------------------------------------------------------------------------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 2 | +| 3 | Definitions ..... | 2 | +| 4 | Abbreviations..... | 2 | +| 5 | Reference models..... | 2 | +| 5.1 | ATU functional model..... | 2 | +| 5.2 | User plane protocol reference model..... | 3 | +| 5.3 | Management plane reference model..... | 3 | +| 5.4 | Application models..... | 4 | +| 5.4.1 | Data service ..... | 4 | +| 5.4.2 | Data with POTS service ..... | 4 | +| 5.4.3 | Intentionally left blank ..... | 5 | +| 5.4.4 | Voice over data service ..... | 5 | +| 6 | Transport Protocol Specific Transmission Convergence (TPS-TC) function ..... | 5 | +| 7 | Physical Media Specific Transmission Convergence (PMS-TC) function ..... | 5 | +| 8 | Physical Media Dependent (PMD) function..... | 5 | +| 9 | Management Protocol Specific Transmission Convergence (MPS-TC) functions ..... | 6 | +| 10 | Control Protocol Specific Transmission Convergence (CPS-TC) functions..... | 6 | +| 11 | Dynamic behaviour..... | 6 | +| | Annex A – Specific requirements for an ADSL system operating in the frequency band above POTS ..... | 7 | +| A.1 | ATU-C functional characteristics (pertains to clause 8) ..... | 7 | +| A.1.1 | ATU-C PMD control parameter settings..... | 7 | +| A.1.2 | ATU-C downstream transmit spectral mask for overlapped spectrum operation..... | 7 | +| A.1.3 | ATU-C transmitter PSD mask for non-overlapped spectrum operation ..... | 9 | +| A.2 | ATU-R functional characteristics (pertains to clause 8) ..... | 11 | +| A.3 | Intentionally left blank ..... | 11 | +| A.4 | Electrical characteristics..... | 11 | +| | Annex B – (void annex)..... | 11 | +| | Annex C – Specific requirements for an ADSL system operating in the same cable as ISDN as defined in ITU-T Rec. G.961 Appendix III ..... | 11 | + +| | | +|---------------------------------------------------------------------------------------------------|----| +| Annex D – ATU-C and ATU-R state diagrams ..... | 12 | +| Annex E – POTS and ISDN-BA splitters ..... | 12 | +| Annex F – ATU performance requirements for Region A (North America)..... | 12 | +| Annex G – (void annex)..... | 12 | +| Annex H – (void annex)..... | 12 | +| Annex I – All digital mode ADSL with improved spectral compatibility with ADSL over
POTS ..... | 13 | +| I.1    ATU-C functional characteristics (pertains to clause 8) ..... | 13 | +| I.1.1    ATU-C control parameter settings ..... | 13 | +| I.1.2    ATU-C downstream transmit spectral mask for overlapped spectrum
operation ..... | 13 | +| I.1.3    ATU-C downstream transmit spectral mask for non-overlapped spectrum
operation ..... | 15 | +| I.2    ATU-R functional characteristics (pertains to clause 8) ..... | 15 | +| I.3    Intentionally left blank ..... | 15 | +| I.4    Electrical characteristics ..... | 16 | +| Annex J – (void annex) ..... | 16 | +| Annex K – TPS-TC functional descriptions ..... | 16 | + +# **Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2)** + +# **1 Scope** + +This Recommendation describes the interface between the telecommunications network and the customer installation in terms of their interaction and electrical characteristics. The requirements of this Recommendation apply only to a single asymmetric digital subscriber line (ADSL). ADSL allows the provision of voiceband services, including POTS and V-series data services, and a number of digital channels. This Recommendation is structured as a delta document to ITU-T Rec. G.992.3. + +The transmission system is designed to operate on mixed gauge two-wire twisted metallic pairs over the existing copper facilities and over the customer premises wiring. The transmission system is based on the use of loop plant cables without loading coils. Bridged taps in the loop plant are acceptable in all but a few unusual situations. + +Operation in a TCM-ISDN noise environment is for further study. + +An overview of Digital Subscriber Line Transceivers can be found in ITU-T Rec. G.995.1. + +This Recommendation describes the second generation of splitterless ADSL, based on the first generation ITU-T Rec. G.992.2. This Recommendation is easily implemented in multi-mode devices that support both G.992.4 and G.992.2 with the following major additions or revisions: + +- Improved application support for an all digital mode of operation and voice over ADSL operation. +- A new packet TPS-TC function and a STM TPS-TC function in addition to the existing ATM support. +- Support for IMA in the ATM TPS-TC. +- Improved configuration capability for each TPS-TC with configuration of latency, BER and minimum, maximum and reserve data rate. +- New line diagnostic procedures available for both successful and unsuccessful initialization scenarios. +- Enhanced on-line reconfiguration capabilities including bit-swaps, dynamic rate repartitioning, and seamless rate adaptation. +- A more flexible TPS-TC function including support for up to 4 frame bearers, 4 latency paths, and control parameters allowing enhanced configuration of the overhead channel. +- Performance improvements including mandatory support for $R = 16$ , one-bit constellations, and trellis coding. +- A more robust initialization procedure that includes splitterless capability features of the G.992.2 fast retrain procedure, CO and CP controlled adaptive signal durations, receiver determined adaptive frequency modulation for data exchange, and an optional adaptive length fast start-up procedure. +- Improved RFI and spectrum management tools including transmit power cutback at both ends of the line, spectrum shaping, sub-carrier black-out lists to avoid RFI, and improved sub-carrier ordering to help mitigate the propagation of RFI from sub-carrier to sub-carrier. +- Power saving features including mandatory reduction of excess margin under management layer control and a new L2 mode with low power features for the central office. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation + +- [1] ITU-T Recommendation G.994.1 (2002), *Handshake procedures for Digital Subscriber Line (DSL) transceivers*. +- [2] ITU-T Recommendation G.992.3 (2002), *Asymmetric Digital Subscriber Line transceivers 2 (ADSL2)*. +- [3] ITU-T Recommendation G.997.1 (1999), *Physical layer management for Digital Subscriber Line (DSL) transceivers*. + +# 3 Definitions + +The definitions in clause 3/G.992.3 shall apply for this Recommendation. + +# 4 Abbreviations + +The abbreviations in clause 4/G.992.3 shall apply for this Recommendation. + +# 5 Reference models + +G.992.4 devices fit within the XDSL Recommendations described in ITU-T Rec. G.995.1. Additionally, G.992.4 devices rely upon constituent components described within ITU-T Recs G.994.1 and G.997.1. This clause provides the necessary functional, application, and protocol reference models so that the subclauses of G.992.4 may be related to these additional Recommendations. + +## 5.1 ATU functional model + +The ATU functional model for G.992.4 shall be identical to that provided in 5.1/G.992.3. Figure 5-1/G.992.3 is duplicated here for reference. + +![Figure 5-1/G.992.4 – ATU functional model. This diagram shows the functional architecture of an ATU, split into ATU-C (Client) and ATU-R (Remote) components. ATU-C includes an OAM interface, NTR, MPS-TC, and two application-specific blocks (TPS-TC #0 and TPS-TC #1) connected via I/F. ATU-R includes MPS-TC, OAM interface, and NTR. The central part is the application invariant main body containing PMS-TC and PMD blocks. Various interfaces and parameters are labeled: γC, α, δC, U, δR, β, γR. The bottom labels categorize sections as 'Application specific', 'Application invariant', 'Unspecified', 'Annexes', and 'Main body'. A reference code G.992.4_F05-1 is present.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg) + +Figure 5-1/G.992.4 – ATU functional model. This diagram shows the functional architecture of an ATU, split into ATU-C (Client) and ATU-R (Remote) components. ATU-C includes an OAM interface, NTR, MPS-TC, and two application-specific blocks (TPS-TC #0 and TPS-TC #1) connected via I/F. ATU-R includes MPS-TC, OAM interface, and NTR. The central part is the application invariant main body containing PMS-TC and PMD blocks. Various interfaces and parameters are labeled: γC, α, δC, U, δR, β, γR. The bottom labels categorize sections as 'Application specific', 'Application invariant', 'Unspecified', 'Annexes', and 'Main body'. A reference code G.992.4\_F05-1 is present. + +G.992.4\_F05-1 + +**Figure 5-1/G.992.4 – ATU functional model** + +## **5.2 User plane protocol reference model** + +The user plane protocol reference model of G.992.4 shall be as defined in 5.2/G.992.3. Figure 5-2/G.992.3 is duplicated here for reference. + +![Figure 5-2/G.992.4 – User plane protocol reference model. This diagram illustrates the user plane protocol stack. On the left, 'Transport protocols (e.g., ATM)' connect to an 'Internal interface' (LT internal interface). The stack includes TPS-TC, PMS-TC, and PMD layers. Interfaces γC, α, δC, U, δR, β, and γR are shown between the client (ATU-C) and remote (ATU-R) sides. The central 'Physical TP media' is connected to a 'User data interface' (S/T) on the right. Labels include LT, ATU-C, ATU-R, NT1, NT1/2, and 'Not specified' blocks. A reference code G.992.4_F05-2 is present.](367926125450c2bc3f4bdca9d59a62ba_img.jpg) + +Figure 5-2/G.992.4 – User plane protocol reference model. This diagram illustrates the user plane protocol stack. On the left, 'Transport protocols (e.g., ATM)' connect to an 'Internal interface' (LT internal interface). The stack includes TPS-TC, PMS-TC, and PMD layers. Interfaces γC, α, δC, U, δR, β, and γR are shown between the client (ATU-C) and remote (ATU-R) sides. The central 'Physical TP media' is connected to a 'User data interface' (S/T) on the right. Labels include LT, ATU-C, ATU-R, NT1, NT1/2, and 'Not specified' blocks. A reference code G.992.4\_F05-2 is present. + +G.992.4\_F05-2 + +**Figure 5-2/G.992.4 – User plane protocol reference model** + +## **5.3 Management plane reference model** + +The management plane protocol reference model of G.992.4 shall be as defined for G.992.3 in 5.3/G.992.3. Figure 5-3/G.992.3 is duplicated here for reference. + +![Figure 5-3/G.992.4 – Management plane protocol reference model. This diagram shows the management plane protocol stack for a Line Terminal (LT) and an ATU-R (ATU-R, NT1, NT1/2) connected via Physical TP media. The LT side includes an Internal interface, a Management protocol(s) (G.997.1) block, and layers for MPS-TC, PMS-TC, and PMD. The ATU-R side includes a User data interface, a Management protocol(s) (G.997.1) block, and layers for MPS-TC, PMS-TC, and PMD. The OAM interface is shown between the two sides, with parameters delta_C and delta_R. The Physical TP media is labeled with U and S/T interfaces. The diagram is labeled G.992.4_F05-3.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Figure 5-3/G.992.4 – Management plane protocol reference model. This diagram shows the management plane protocol stack for a Line Terminal (LT) and an ATU-R (ATU-R, NT1, NT1/2) connected via Physical TP media. The LT side includes an Internal interface, a Management protocol(s) (G.997.1) block, and layers for MPS-TC, PMS-TC, and PMD. The ATU-R side includes a User data interface, a Management protocol(s) (G.997.1) block, and layers for MPS-TC, PMS-TC, and PMD. The OAM interface is shown between the two sides, with parameters delta\_C and delta\_R. The Physical TP media is labeled with U and S/T interfaces. The diagram is labeled G.992.4\_F05-3. + +**Figure 5-3/G.992.4 – Management plane protocol reference model** + +## 5.4 Application models + +The application models for G.992.4 are based upon the generic reference configuration described in 6.1/G.995.1 as are the application models for G.992.3. The two generic application models defined in 5.4/G.992.3 shall be used for G.992.4. Figure 5-5/G.992.3 is duplicated here for reference. This application model for remote splitterless deployment is intended to be used more prevalently with G.992.4. + +![Figure 5-4/G.992.4 – Generic application reference model for splitterless remote deployment. This diagram illustrates the generic application reference model for splitterless remote deployment. It shows a Broadband network connected to a V-C (V-C) block containing PH Y and ATU-C. The V-C block is connected to a Narrow-band network (GSTN or ISDN) via a Splitter C (hpf, lpf). The V-C block is also connected to a Customer premises wiring (CP Wiring carries POTS or ISDN and ADSL service) via a U-C 2 interface. The Customer premises wiring is connected to a T/S (T/S) block containing ATU-R, hpf, and PH Y. The T/S block is connected to a Home network (CPE) and a Telephone set, voiceband modem, or ISDN terminal (optional). The diagram is labeled G.992.4_F05-4.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg) + +Figure 5-4/G.992.4 – Generic application reference model for splitterless remote deployment. This diagram illustrates the generic application reference model for splitterless remote deployment. It shows a Broadband network connected to a V-C (V-C) block containing PH Y and ATU-C. The V-C block is connected to a Narrow-band network (GSTN or ISDN) via a Splitter C (hpf, lpf). The V-C block is also connected to a Customer premises wiring (CP Wiring carries POTS or ISDN and ADSL service) via a U-C 2 interface. The Customer premises wiring is connected to a T/S (T/S) block containing ATU-R, hpf, and PH Y. The T/S block is connected to a Home network (CPE) and a Telephone set, voiceband modem, or ISDN terminal (optional). The diagram is labeled G.992.4\_F05-4. + +**Figure 5-4/G.992.4 – Generic application reference model for splitterless remote deployment** + +### 5.4.1 Data service + +The application model of G.992.4 for delivering data service is the same as the application model defined in 5.4.1/G.992.3. + +### 5.4.2 Data with POTS service + +The application model of G.992.4 for delivering data with POTS service of G.992.4 is the same as the application model defined in 5.4.2/G.992.3. + +### 5.4.3 Intentionally left blank + +This heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +### 5.4.4 Voice over data service + +The application model for delivering voice and data over G.992.4 is the same as the application model defined in 5.4.4/G.992.3. + +# 6 Transport Protocol Specific Transmission Convergence (TPS-TC) function + +This Recommendation provides procedures for the transport of the frame bearers of one to four unidirectional TPS-TC functions in both the upstream and downstream directions. The ATU TPS-TC transport capabilities and functions, interfaces, and procedures shall be as defined in clause 6/G.992.3 and appropriate subclauses of Annex K/G.992.3. + +The control parameters of the TPS-TC function shall be as defined in Table 6-1/G.992.3 and appropriate subclauses of Annex K/G.992.3. The valid control parameter values shall be as defined in 6.3.1/G.992.3, and the valid control settings shall be as defined in 6.3.2/G.992.3 except that mandatory control settings for the TPS-TC shall be limited and shall not exceed a net downstream data rate (referenced to the input of the PMS-TC function) of 1.536 Mbit/s and a net upstream data rate of 512 kbit/s. Support for data rates above the mandatory rates is optional and allowed. + +The G.994.1 CL and MS information formats for the TPS-TC function shall be as defined in Table 6-2/G.992.3 and appropriate subclauses of Annex K/G.992.3. During all G.994.1 message, the bit(s) corresponding to supporting G.992.4 annexes shall be asserted. + +# 7 Physical Media Specific Transmission Convergence (PMS-TC) function + +The primary purpose of the ATU PMS-TC function is to provide for the multiplexing and transport of several channels of information. The ATU PMS-TC transport capabilities and functions, interfaces, control variables, and procedures shall be as defined in clause 7/G.992.3 with the following exceptions or clarifications in specific subclauses. + +| | | +|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Subclause 7.8.1 | References in G.992.3 to a sample clock of 2.208 MHz shall be replaced with 1.104 MHz for G.992.4. Similarly, reference to 453 ns in G.992.3 shall be replaced with 905 ns for G.992.4 | +| Subclause 7.10.1 | During all G.994.1 message, the SPAR(1) bit(s) corresponding to supported G.992.4 Annex(es) shall be asserted. | +| Subclause 7.12.1.1 | The upper bound on the value of $\sum L_p$ shall be less than or equal to 192. | + +# 8 Physical Media Dependent (PMD) function + +The primary purpose of the ATU Physical Media Dependent (PMD) function is to provide for the transport of a bitstream over the physical medium (i.e., over the copper pairs) in both the upstream and downstream directions. The ATU PMD transport capabilities and functions, interfaces, control variables, and procedures shall be as defined in clause 8/G.992.3 with the following exceptions or clarifications in specific subclauses. + +| | | +|----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Subclause 8.5.1 | The value of the control parameter NSCds shall be as defined in the annexes of this Recommendation. The number of downstream sub-carrier defined in those annexes shall be used when a G.994.1 SPAR(1) bit corresponding to the annex is asserted in a MS command. | +| Subclause 8.10 | The transmitter spectral masks for the different service options are defined in annexes of this Recommendation. The maximum passband PSD, maximum stopband PSD and maximum aggregate transmit power defined in those annexes shall be used when the G.994.1 SPAR(1) bit corresponding to the annex is asserted in a MS command. | +| Subclause 8.13.2 | During all G.994.1 message, the SPAR(1) bit(s) corresponding to supported G.992.4 annex(es) shall be asserted. | +| Subclause 8.13.2.1.1 | The NPAR(2) bit corresponding to Tones 1-32 shall be ignored. | +| Subclause 8.13.2.1.2 | The NPAR(2) bit corresponding to Tones 1-32 shall be ignored. | +| Subclause 8.13.2.2.1 | The NPAR(2) bit corresponding to Tones 1-32 shall be ignored. | +| Subclause 8.13.2.2.2 | The NPAR(2) bit corresponding to Tones 1-32 shall be ignored. | +| Subclause 8.13.3.1.2 | The sub-carriers used for C-COMB symbols shall be limited to those below NSCds. | +| Subclause 8.13.5.1.4 | The sub-carriers used for C-MEDLEY shall be limited to those below NSCds, and the data pattern used to create symbols shall be the same as in G.992.3. 256 bit-pairs shall be extracted from the PRBS generator every symbol, but the bits corresponding to all sub-carriers above NSCds-1 shall be effectively ignored. | +| Subclause 8.13.6.2.1 | The data exchanged in R-MSG2 message shall be limited to sub-carriers below NSCds. The R-MSG2 message bits corresponding to all sub-carrier above NSCds-1 shall be set to zero and ignored by the receiver. The length of the R-MSG2 message of G.992.4 is the same as G.992.3. | + +# 9 Management Protocol Specific Transmission Convergence (MPS-TC) functions + +The primary purpose of the ATU MPS-TC function is to provide for the transport of a clear eoc and command messages. Additionally, the MPS-TC controls the implementation of power management modes. The ATU MPS-TC transport capabilities and functions, interfaces, and procedures shall be as defined in clause 9/G.992.3 with the following exceptions or clarifications in specific subclauses. + +| | | +|--------------------|------------------------------------------------------------------------------------------------------------------------------------------------------| +| Subclause 9.4.1.10 | The number of sub-carriers shall be NSC. The test parameters that have per sub-carriers values shall only return values related to sub-carriers NSC. | +|--------------------|------------------------------------------------------------------------------------------------------------------------------------------------------| + +# 10 Control Protocol Specific Transmission Convergence (CPS-TC) functions + +The control reference model of G.992.4 is for further study. + +# 11 Dynamic behaviour + +The ATUs contain several dynamic behaviours, including initialization, power management, and on-line reconfiguration. These shall be as described in clause 10/G.992.3. + +## Annex A + +## Specific requirements for an ADSL system operating in the frequency band above POTS + +This annex defines parameters that have been left unspecified in the body of this Recommendation because they are specific to an ADSL service that is frequency-division duplexed with and over POTS. + +### A.1 ATU-C functional characteristics (pertains to clause 8) + +#### A.1.1 ATU-C PMD control parameter settings + +The ATU-C PMD Control Parameter Settings shown in Table A.1 shall be as shown in that table in accordance with the definitions in clause 8. All the values except NSCds may be changed relative to the shown value during G.994.1 as described in clause 8. The values that are different from G.992.3 are NSCds, and MAXNOMATPds. + +**Table A.1/G.992.4 – ATU-C control parameter settings for the PMD transmit function** + +| Parameter | Default setting | Characteristics | +|-------------|-----------------|-----------------------------------------------------------------------------------------| +| NSCds | 128 | | +| NOMPSDds | –40 dBm/Hz | Setting may be changed relative to this value during G.994.1 phase, see 8.13.2/G.992.3. | +| MAXNOMPSDds | –40 dBm/Hz | Setting may be changed relative to this value during G.994.1 phase, see 8.13.2/G.992.3. | +| MAXNOMATPds | 17.2 dBm | Setting may be changed relative to this value during G.994.1 phase, see 8.13.2/G.992.3. | + +#### A.1.2 ATU-C downstream transmit spectral mask for overlapped spectrum operation + +The passband is defined differently than G.992.3 Annex A as the band from 25.875 to 552 kHz and is the widest possible band used (i.e., for ADSL over POTS implemented with overlapped spectrum). Limits defined within the passband apply also to any narrower bands used. + +Figure A.1 defines the spectral mask for the transmit signal. The low-frequency stop-band is defined as frequencies below 25.875 kHz and includes the POTS band, the high-frequency stop-band is defined as frequencies greater than 552 kHz. + +![Graph of PSD in dBm/Hz vs Frequency in kHz for ATU-C transmitter. The graph shows a piecewise linear mask with various peaks and slopes. Key points include: 0-4 kHz at -97.5 peak (+15 dBm), 4 kHz at -92.5 peak, 21 dB/octave slope from 4 to 25.875 kHz, -36.5 peak from 25.875 to 552 kHz, -36 dB/octave slope from 552 to 956 kHz, -65 peak from 956 to 1800 kHz, -72 dB/octave slope from 1800 to 2290 kHz, -90 peak from 2290 to 3093 kHz, and a dashed line for 4545-11040 kHz at -50 dBm power in any 1 MHz sliding window.](7c1f9e78e0f033d391b687f1652f6e47_img.jpg) + +Graph of PSD in dBm/Hz vs Frequency in kHz for ATU-C transmitter. The graph shows a piecewise linear mask with various peaks and slopes. Key points include: 0-4 kHz at -97.5 peak (+15 dBm), 4 kHz at -92.5 peak, 21 dB/octave slope from 4 to 25.875 kHz, -36.5 peak from 25.875 to 552 kHz, -36 dB/octave slope from 552 to 956 kHz, -65 peak from 956 to 1800 kHz, -72 dB/octave slope from 1800 to 2290 kHz, -90 peak from 2290 to 3093 kHz, and a dashed line for 4545-11040 kHz at -50 dBm power in any 1 MHz sliding window. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|--------------------------|--------------------------------------------------------------------------------------------------------------------| +| $0 < f < 4$ | $-97.5$ , with max power in the in 0-4 kHz band of $+15$ dBm | +| $4 < f < 25.875$ | $-92.5 + 21 \times \log_2(f/4)$ | +| $25.875 < f < 552$ | $-36.5$ | +| $552-956$ | $-36.5 - 36 \times \log(f/552)/\log(2)$ | +| $956-1800$ | $-65$ | +| $1800-2290$ | $-65 - 72 \times \log(f/1800)/\log(2)$ | +| $2290-3093$ | $-90$ | +| $3093 < f < 4545$ | $-90$ peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of $(-36.5 - 36 \times \log_2(f/1104) + 60)$ dBm | +| $4545 < f < 11\,040$ | $-90$ peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of $-50$ dBm | + +NOTE 1 – All PSD measurements are in $100\ \Omega$ ; the POTS band total power measurement is in $600\ \Omega$ . + +NOTE 2 – The breakpoint frequencies and PSD values are exact; the indicated slopes are approximate. + +NOTE 3 – Above $25.875$ kHz, the peak PSD shall be measured with a $10$ kHz resolution bandwidth. + +NOTE 4 – The power in a $1$ MHz sliding window is measured in a $1$ MHz bandwidth, starting at the measurement frequency. + +NOTE 5 – The step in the PSD mask at $4$ kHz is to protect V.90 performance. Originally, the PSD mask continued the $21$ dB/octave slope below $4$ kHz hitting a floor of $-97.5$ dBm/Hz at $3400$ Hz. It was recognized that this might impact V.90 performance, and so the floor was extended to $4$ kHz. + +NOTE 6 – All PSD and power measurements shall be made at the U-C interface (see Figure 5-4). + +G.992.4\_FA-1 + +**Figure A.1/G.992.4 – ATU-C transmitter PSD mask for overlapped spectrum operation** + +##### A.1.2.1 Passband PSD and response + +Across the whole passband, the transmit PSD level shall not exceed the maximum passband transmit PSD level, defined as: + +- NOMPSDds + 1 dB, for initialization signals up to and including the Channel Discovery Phase; +- REFPSDds + 1 dB, during the remainder of initialization, starting with the Transceiver Training Phase; + +- MAXNOMPSDDs – PCBds + 3.5 dB, during showtime. + +The group delay variation over the passband shall not exceed 50 $\mu\text{s}$ . + +The maximum passband transmit PSD level allows for a 1 dB of non-ideal transmit filter effects (e.g., passband ripple and transition band rolloff). + +For spectrum management purposes, the PSD template nominal passband transmit PSD level is $-40 \text{ dBm/Hz}$ . + +##### **A.1.2.2 Aggregate transmit power** + +There are three different PSD masks for the ATU-C transmit signal, depending on the type of signal sent (see A.1.2.1). In all cases: + +- the aggregate transmit power in the voiceband, measured at the U-C interface, and that is delivered to the Public Switched Telephone Network (PSTN) interface shall not exceed $+15 \text{ dBm}$ (see ITU-T Rec. G.996.1 for method of measurement); +- the aggregate transmit power across the whole passband shall not exceed (MAXNOMATPds-PCBds) by more than 0.5 dB, in order to accommodate implementation tolerances, and not exceed $17.7 \text{ dBm}$ . +- the aggregate transmit power over the 0 to 11.04 MHz band shall not exceed (MAXNOMATPds-PCBds) by more than 0.9 dB, in order to account for residual transmit power in the stop bands and implementation tolerances. + +For spectrum management purposes, the PSD template nominal passband aggregate transmit power is $17.2 \text{ dBm}$ . + +The power emitted by the ATU-C is limited by the requirements in this subclause. Notwithstanding these requirements, it is assumed that the ADSL will comply with applicable national requirements on emission of electromagnetic energy. + +#### **A.1.3 ATU-C transmitter PSD mask for non-overlapped spectrum operation** + +Figure A.2 defines the spectral mask for the ATU-C transmitted signal, which results in reduced NEXT into the ADSL upstream band, relative to the mask in A.1.2. Adherence to this mask will in many cases result in improved upstream performance of the other ADSL systems in the same or adjacent binder group, with the improvement dependent upon the other interferers. This mask differs from the mask in A.1.2 only in the band from 4 kHz to 138 kHz. + +The passband is defined as the band from 138 to 552 kHz. Limits defined within the passband apply also to any narrower bands used. + +The low-frequency stop-band is defined as frequencies below 138 kHz and includes the POTS band, the high-frequency stop-band is defined as frequencies greater than 552 kHz. + +![Figure A.2/G.992.4 – ATU-C transmitter PSD mask for non-overlapped spectrum operation. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has major ticks at 0, 4, 80, 138, 552, 956, 1800, 2290, 3093, 4545, and 11 040 kHz. The y-axis has major ticks at -97.5, -92.5, -72.5, -36.5, -44.2, -65, -72, -90, and -50 dBm/Hz. The PSD mask is defined by several segments: 0-4 kHz is a flat floor at -97.5 dBm/Hz with a maximum power of +15 dBm; 4-80 kHz has a slope of 4.63 dB/octave; 80-138 kHz has a slope of 36 dB/octave; 138-552 kHz is a flat peak at -36.5 dBm/Hz; 552-956 kHz has a slope of -36 dB/octave; 956-1800 kHz is a flat peak at -65 dBm/Hz; 1800-2290 kHz has a slope of -72 dB/octave; 2290-3093 kHz is a flat peak at -90 dBm/Hz; 3093-4545 kHz is a flat peak at -90 dBm/Hz with a maximum power of -36.5 dBm/Hz in any 1 MHz sliding window; 4545-11 040 kHz is a flat peak at -90 dBm/Hz with a maximum power of -50 dBm in any 1 MHz sliding window.](ad29805cd4f64ad2828e14feb66de664_img.jpg) + +Figure A.2/G.992.4 – ATU-C transmitter PSD mask for non-overlapped spectrum operation. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has major ticks at 0, 4, 80, 138, 552, 956, 1800, 2290, 3093, 4545, and 11 040 kHz. The y-axis has major ticks at -97.5, -92.5, -72.5, -36.5, -44.2, -65, -72, -90, and -50 dBm/Hz. The PSD mask is defined by several segments: 0-4 kHz is a flat floor at -97.5 dBm/Hz with a maximum power of +15 dBm; 4-80 kHz has a slope of 4.63 dB/octave; 80-138 kHz has a slope of 36 dB/octave; 138-552 kHz is a flat peak at -36.5 dBm/Hz; 552-956 kHz has a slope of -36 dB/octave; 956-1800 kHz is a flat peak at -65 dBm/Hz; 1800-2290 kHz has a slope of -72 dB/octave; 2290-3093 kHz is a flat peak at -90 dBm/Hz; 3093-4545 kHz is a flat peak at -90 dBm/Hz with a maximum power of -36.5 dBm/Hz in any 1 MHz sliding window; 4545-11 040 kHz is a flat peak at -90 dBm/Hz with a maximum power of -50 dBm in any 1 MHz sliding window. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|--------------------------|----------------------------------------------------------------------------------------------------------------| +| $0 < f < 4$ | -97.5, with max power in the in 0-4 kHz band of +15 dBm | +| $4 < f < 80$ | $-92.5 + 4.63 \times \log_2(f/4)$ | +| $80 < f < 138$ | $-72.5 + 36 \times \log_2(f/80)$ | +| $138 < f < 552$ | -36.5 | +| 552-956 | $-36.5 - 36 \times \log(f/552)/\log(2)$ | +| 956-1800 | -65 | +| 1800-2290 | $-65 - 72 \times \log(f/1800)/\log(2)$ | +| 2290-3093 | -90 | +| $3093 < f < 4545$ | -90 peak, with max power in the $[f, f+1 \text{ MHz}]$ window of $(-36.5 - 36 \times \log_2(f/1104) + 60)$ dBm | +| $4545 < f < 11 \ 040$ | -90 peak, with max power in the $[f, f+1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – All PSD measurements are in 100 $\Omega$ ; the POTS band total power measurement is in 600 $\Omega$ . + +NOTE 2 – The breakpoint frequencies and PSD values are exact; the indicated slopes are approximate. + +NOTE 3 – Above 25.875 kHz, the peak PSD shall be measured with a 10 kHz resolution bandwidth. + +NOTE 4 – The power in a 1 MHz sliding window is measured in a 1 MHz bandwidth, starting at the measurement frequency. + +NOTE 5 – The step in the PSD mask at 4 kHz is to protect V.90 performance. Originally, the PSD mask continued the 21 dB/octave slope below 4 kHz hitting a floor of -97.5 dBm/Hz at 3400 Hz. It was recognized that this might impact V.90 performance, and so the floor was extended to 4 kHz. + +NOTE 6 – All PSD and power measurements shall be made at the U-C interface (see Figure 5-4). + +G.992.4\_FA-2 + +**Figure A.2/G.992.4 – ATU-C transmitter PSD mask for non-overlapped spectrum operation** + +##### A.1.3.1 Passband PSD and response + +Across the whole passband, the transmit PSD level shall not exceed the maximum passband transmit PSD level defined in A.1.2.1. + +##### **A.1.3.2 Aggregate transmit power** + +In all cases the aggregate transmit power shall meet the requirements defined in A.1.2.2, Aggregate transmit power. In addition, for non-overlapped spectrum operation, the aggregate transmit power across the whole passband shall not exceed 16.7 dBm. + +For spectrum management purposes, the PSD template nominal passband aggregate transmit power is 16.2 dBm. + +### **A.2 ATU-R functional characteristics (pertains to clause 8)** + +The ATU-R PMD control parameter settings, ARU-R upstream transmit spectrum masks, ATU-R passband PSD and response, and ATU-R transmit aggregate transmit power shall conform to A.2/G.992.3. + +### **A.3 Intentionally left blank** + +This heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +### **A.4 Electrical characteristics** + +The requirements for ATU-R impedance states, ATU-R POTS current and voltage specifications, electrical characteristics of the ATU-R and ATU-C while in the active state, and electrical characteristics of the ATU-R while in high impedance state as defined in A.4/G.992.3 shall be satisfied. The impedance and passband requirements for this clause shall apply across the entire passband as defined for G.992.3 in A.4 (i.e., not only to the passband defined for this Recommendation). + +## **Annex B** + +(void annex) + +This annex heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +## **Annex C** + +## **Specific requirements for an ADSL system operating in the same cable as ISDN as defined in ITU-T Rec. G.961 Appendix III** + +The use of G.992.4 over POTS coexisting with TCM-ISDN is under study. + +# **Annex D** + +## **ATU-C and ATU-R state diagrams** + +The ATU-C and ATU-R state diagrams shall be as described in Annex D/G.992.3. + +# **Annex E** + +## **POTS and ISDN-BA splitters** + +G.992.4 is intended for installation primarily without splitters. However, if splitters are provided for operation with POTS they shall be as described in Annex E/G.992.3. The description of splitters for use with ISDN-BA described in Annex E/G.992.3 does not apply. + +# **Annex F** + +## **ATU performance requirements for Region A (North America)** + +The contents of this annex of G.992.4 are for further study. + +## **Annex G** + +(void annex) + +This annex heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +## **Annex H** + +(void annex) + +This annex heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +## **Annex I** + +## **All digital mode ADSL with improved spectral compatibility with ADSL over POTS** + +This annex defines parameters that have been left unspecified in the body of this Recommendation because they are specific to an ADSL service that is provided without an underlying frequency-division duplexed service. + +### **I.1 ATU-C functional characteristics (pertains to clause 8)** + +The ATU-C shall support wetting current functionality and related characteristics. The operator may disable the provisioning of wetting current at the ATU-C. + +#### **I.1.1 ATU-C control parameter settings** + +The ATU-C PMD Control Parameter Settings shown in Table A.1 shall be as shown in that table in accordance with the definitions in clause 8. All the values except NSCds may be changed relative to the shown value during G.994.1 as described in clause 8. + +#### **I.1.2 ATU-C downstream transmit spectral mask for overlapped spectrum operation** + +The passband is defined differently from Annex I/G.992.3 as the band from 3 to 552 kHz and is the widest possible band used (i.e., implemented with overlapped spectrum). Limits defined within the passband apply also to any narrower bands used. + +Figure I.1 defines the spectral mask for the transmit signal. The low-frequency stop-band is defined as frequencies below 3 kHz, the high-frequency stop-band is defined as frequencies greater than 552 kHz. + +![Graph of PSD in dBm/Hz vs Frequency in kHz for ATU-C transmitter. The graph shows a piecewise linear mask with various peaks and slopes. Key points include: 0 to 1.5 kHz at -48.5 dBm/Hz; 1.5 to 3 kHz rising at 21 dB/octave to -36.5 dBm/Hz; 3 to 552 kHz flat at -36.5 dBm/Hz; 552 to 956 kHz falling at -36 dB/octave to -65 dBm/Hz; 956 to 1800 kHz flat at -65 dBm/Hz; 1800 to 2290 kHz falling at -72 dB/octave to -90 dBm/Hz; 2290 to 3093 kHz flat at -90 dBm/Hz; 3093 to 4545 kHz flat at -90 dBm/Hz; 4545 to 11040 kHz flat at -90 dBm/Hz. A dashed line indicates a -50 dBm power limit in any 1 MHz sliding window above 4545 kHz.](3102c32204f998dba666e1e915d5babf_img.jpg) + +Graph of PSD in dBm/Hz vs Frequency in kHz for ATU-C transmitter. The graph shows a piecewise linear mask with various peaks and slopes. Key points include: 0 to 1.5 kHz at -48.5 dBm/Hz; 1.5 to 3 kHz rising at 21 dB/octave to -36.5 dBm/Hz; 3 to 552 kHz flat at -36.5 dBm/Hz; 552 to 956 kHz falling at -36 dB/octave to -65 dBm/Hz; 956 to 1800 kHz flat at -65 dBm/Hz; 1800 to 2290 kHz falling at -72 dB/octave to -90 dBm/Hz; 2290 to 3093 kHz flat at -90 dBm/Hz; 3093 to 4545 kHz flat at -90 dBm/Hz; 4545 to 11040 kHz flat at -90 dBm/Hz. A dashed line indicates a -50 dBm power limit in any 1 MHz sliding window above 4545 kHz. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|--------------------------|----------------------------------------------------------------------------------------------------------------| +| $0 < f < 1.5$ | -48.5 | +| $1.5 < f < 3$ | $-36.5 + 12 \times \log_2(f/3)$ | +| $3 < f < 552$ | -36.5 | +| $552-956$ | $-36.5 - 36 \times \log(f/552)/\log(2)$ | +| $956-1800$ | -65 | +| $1800-2290$ | $-65 - 72 \times \log(f/1800)/\log(2)$ | +| $2290-3093$ | -90 | +| $3093 < f < 4545$ | -90 peak, with max power in the $[f, f+1 \text{ MHz}]$ window of $(-36.5 - 36 \times \log_2(f/1104) + 60)$ dBm | +| $4545 < f < 11040$ | -90 peak, with max power in the $[f, f+1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – All PSD measurements are in 100 $\Omega$ . +NOTE 2 – The breakpoint frequencies and PSD values are exact; the indicated slopes are approximate. +NOTE 3 – Above 3 kHz, the peak PSD shall be measured with a 10 kHz resolution bandwidth. Below 3 kHz, the peak PSD shall be measured with a 100 Hz resolution bandwidth. +NOTE 4 – The power in a 1 MHz sliding window is measured in a 1 MHz bandwidth, starting at the measurement frequency. +NOTE 5 – All PSD and power measurements shall be made at the U-C interface. + +G.992.4\_FI-1 + +**Figure I.1/G.992.4 – ATU-C transmitter PSD mask for overlapped spectrum operation** + +NOTE – When deployed in the same cable as ADSL-over-POTS (Annex A/G.992.1 and G.992.2 Annexes A & B), there may be a spectral compatibility issue between the two systems due to the overlap of the All-Digital Loop downstream channel with the ADSL-over-POTS upstream channel at frequencies below 138 kHz. Detailed study of spectrum compatibility is referred to regional bodies. Deployment restrictions for systems using the downstream PSD masks defined in this annex may be imposed (e.g., by the regional regulatory authority). + +##### I.1.2.1 Passband PSD and response + +Across the whole passband, the transmit PSD level shall not exceed the maximum passband transmit PSD level, defined as: + +- NOMPSDd + 1 dB, for initialization signals up to and including the Channel Discovery Phase; + +- REFPSDds + 1 dB, during the remainder of initialization, starting with the Transceiver Training Phase; +- MAXNOMPSDds – PCBds + 3.5 dB, during showtime. + +The group delay variation over the passband shall not exceed 50 $\mu\text{s}$ . + +The maximum passband transmit PSD level allows for a 1 dB of non-ideal transmit filter effects (e.g., passband ripple and transition band rolloff). + +For spectrum management purposes, the PSD template nominal passband transmit PSD level is $-40\text{ dBm/Hz}$ . + +##### **I.1.2.2 Aggregate transmit power** + +There are three different PSD masks for the ATU-C transmit signal, depending on the type of signal sent (see I.1.2.1). In all cases, + +- the aggregate transmit power across the whole passband shall not exceed (MAXNOMATPds-PCBds) by more than 0.5 dB, in order to accommodate implementation tolerances and shall not exceed 17.7 dBm; +- the aggregate transmit power over the 0 to 11.04 MHz band shall not exceed (MAXNOMATPds – PCBds) by more than 0.9 dB, in order to account for residual transmit power in the stop bands and implementation tolerances. + +For spectrum management purposes, the PSD template nominal passband aggregate transmit power is 17.2 dBm. + +The power emitted by the ATU-C is limited by the requirements in this subclause. Notwithstanding these requirements, it is assumed that the ADSL will comply with applicable national requirements on emission of electromagnetic energy. + +#### **I.1.3 ATU-C downstream transmit spectral mask for non-overlapped spectrum operation** + +The ATU-C transmit spectral mask shall be identical to the ATU-C transmit spectral mask for non-overlapped spectrum operation over POTS, as defined in A.1.3, with following modification: + +For $0 < f < 4$ , the PSD shall be below $-97.5\text{ dBm/Hz}$ (i.e., no extra limitation of max power in 0-4 kHz band). + +##### **I.1.3.1 Passband PSD and response** + +See A.1.2.1. + +##### **I.1.3.2 Aggregate transmit power** + +See A.1.3.2. + +### **I.2 ATU-R functional characteristics (pertains to clause 8)** + +The ATU-R PMD control parameter settings, ATU-R downstream transmit spectrum masks, ATU-R passband PSD and response, and ATU-R transmit aggregate transmit power shall conform to I.2/G.992.3. + +### **I.3 Intentionally left blank** + +This heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +### **I.4 Electrical characteristics** + +The requirements for ATU-R POTS current and voltage specifications, electrical characteristics of the ATU-R and ATU-C while in the active state, as defined in I.4/G.992.3, shall be satisfied. The impedance and passband requirements for this clause shall apply across the entire passband as defined for G.992.3 in Annex I (i.e., not only to the passband defined for this Recommendation). + +## **Annex J** + +(void annex) + +This annex heading and section are intentionally left void to facilitate alignment of the G.992.4 and G.992.3 table of contents. + +## **Annex K** + +## **TPS-TC functional descriptions** + +The various TPS-TC types that may be used within the G.992.4 transceivers are described in Annex K/G.992.3. If a TPS-TC type is provided, it shall be implemented as described in Annex K/G.992.3 except as modified by clause 6 of this Recommendation. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | + +![Barcode with the number 23104 between two asterisks.](05c9994c1f5daf53d0d9b107657d7a17_img.jpg) + +A barcode consisting of vertical black lines of varying widths. 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CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **Recommendation ITU-T G.993.2** + +# **Very high speed digital subscriber line transceivers 2 (VDSL2)** + +# **Summary** + +Recommendation ITU-T G.993.2 specifies an access technology that exploits the existing infrastructure of copper wires that were originally deployed for POTS services. It can be deployed from central offices, from fibre-fed cabinets located near customer premises, or within buildings. This Recommendation is an enhancement to ITU-T G.993.1 that supports asymmetric and symmetric transmission at a bidirectional net data rate up to 200 Mbit/s on twisted pairs using a bandwidth up to 30 MHz. + +This version of this Recommendation integrates all the previous amendments and corrigenda with the 2011 version of Recommendation ITU-T G.993.2. + +This version of Recommendation ITU-T G.993.2 corrects or adds the following functionality: + +- Method to address the misestimation of the SNR during MEDLEY (Amendment 2) +- Segmentation of SOC messages for profile 35b (Corrigendum 1) +- Annex D: Long reach VDSL2 (Amendment 3) +- Near-end anomalies for loss-of-power, host-reinit and spontaneous interruptions (Amendment 4) +- Addition of operation per the North American region for profile 35b (Annex Q) (Amendment 4) +- Addition of operation per the China region for profile 35b (Annex Q) (new) +- Addition of Successful SRA counter (new) +- Long reach VDSL2 corrigendum related to MAXNOMATP (new) +- Corrigendum to MAXMASK definition in Table 7-5 (new) +- Corrigendum to use of US0 with 35b profile for the North-America region (new). + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|------------------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.993.2 | 2006-02-17 | 15 | 11.1002/1000/8548 | +| 1.1 | ITU-T G.993.2 (2006) Cor. 1 | 2006-12-14 | 15 | 11.1002/1000/8992 | +| 1.2 | ITU-T G.993.2 (2006) Amd. 1 | 2007-04-06 | 15 | 11.1002/1000/8991 | +| 1.3 | ITU-T G.993.2 (2006) Amd. 1 Cor. 1 | 2007-07-29 | 15 | 11.1002/1000/9164 | +| 1.4 | ITU-T G.993.2 (2006) Cor. 2 | 2007-07-29 | 15 | 11.1002/1000/9166 | +| 1.5 | ITU-T G.993.2 (2006) Amd. 2 | 2008-02-06 | 15 | 11.1002/1000/9165 | +| 1.6 | ITU-T G.993.2 (2006) Amd. 3 | 2008-08-22 | 15 | 11.1002/1000/9387 | +| 1.7 | ITU-T G.993.2 (2006) Amd. 4 | 2009-01-13 | 15 | 11.1002/1000/9654 | +| 1.8 | ITU-T G.993.2 (2006) Cor. 3 | 2009-06-29 | 15 | 11.1002/1000/9890 | +| 1.9 | ITU-T G.993.2 (2006) Amd. 5 | 2010-04-22 | 15 | 11.1002/1000/10413 | +| 1.10 | ITU-T G.993.2 (2006) Amd. 6 | 2010-11-29 | 15 | 11.1002/1000/11022 | +| 1.11 | ITU-T G.993.2 (2006) Cor. 4 | 2011-04-13 | 15 | 11.1002/1000/11149 | +| 1.12 | ITU-T G.993.2 (2006) Amd. 7 | 2011-06-22 | 15 | 11.1002/1000/11148 | +| 2.0 | ITU-T G.993.2 | 2011-12-16 | 15 | 11.1002/1000/11415 | +| 2.1 | ITU-T G.993.2 (2011) Amd. 1 | 2012-04-06 | 15 | 11.1002/1000/11502 | +| 2.2 | ITU-T G.993.2 (2011) Cor. 1 | 2012-06-13 | 15 | 11.1002/1000/11642 | +| 2.3 | ITU-T G.993.2 (2011) Amd. 2 | 2012-12-07 | 15 | 11.1002/1000/11795 | +| 2.4 | ITU-T G.993.2 (2011) Amd. 3 | 2013-04-22 | 15 | 11.1002/1000/11888 | +| 2.5 | ITU-T G.993.2 (2011) Amd. 4 | 2013-08-29 | 15 | 11.1002/1000/11992 | +| 2.6 | ITU-T G.993.2 (2011) Amd. 5 | 2014-01-13 | 15 | 11.1002/1000/12096 | +| 2.7 | ITU-T G.993.2 (2011) Amd. 6 | 2015-05-22 | 15 | 11.1002/1000/12371 | +| 3.0 | ITU-T G.993.2 | 2015-01-13 | 15 | 11.1002/1000/12370 | +| 3.1 | ITU-T G.993.2 (2015) Amd. 1 | 2015-11-06 | 15 | 11.1002/1000/12563 | +| 3.2 | ITU-T G.993.2 (2015) Amd. 2 | 2016-03-29 | 15 | 11.1002/1000/12796 | +| 3.3 | ITU-T G.993.2 (2015) Cor. 1 | 2016-11-13 | 15 | 11.1002/1000/13120 | +| 3.4 | ITU-T G.993.2 (2015) Amd. 3 | 2018-02-09 | 15 | 11.1002/1000/13306 | +| 3.5 | ITU-T G.993.2 (2015) Amd. 4 | 2018-05-07 | 15 | 11.1002/1000/13528 | +| 4.0 | ITU-T G.993.2 | 2019-02-22 | 15 | 11.1002/1000/13747 | + +## Keywords + +Broadband access, copper pairs, DMT modulation, 100 Mbit/s. + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +# INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +| | | Page | +|------|------------------------------------------------------------------------------|------| +| 1 | Scope ..... | 1 | +| 2 | References ..... | 3 | +| 3 | Definitions ..... | 4 | +| 4 | Abbreviations and acronyms ..... | 8 | +| 5 | Reference models ..... | 11 | +| 5.1 | VTU functional model..... | 11 | +| 5.2 | User plane protocol reference model..... | 13 | +| 5.3 | Management plane reference model..... | 14 | +| 5.4 | Application reference models..... | 15 | +| 6 | Profiles..... | 19 | +| 6.1 | Definition..... | 19 | +| 6.2 | Profile parameter definitions ..... | 23 | +| 6.3 | Profile compliance..... | 26 | +| 7 | Transmission medium interface characteristics..... | 26 | +| 7.1 | Duplexing method and band plan construction..... | 26 | +| 7.2 | Power spectral density (PSD)..... | 27 | +| 7.3 | Termination impedance ..... | 43 | +| 7.4 | Longitudinal conversion loss..... | 43 | +| 8 | Transport protocol specific transmission convergence (TPS-TC) function ..... | 44 | +| 8.1 | The user data TPS-TC ..... | 44 | +| 8.2 | Management TPS-TC (MPS-TC)..... | 46 | +| 8.3 | Network timing reference TPS-TC (NTR-TC) ..... | 50 | +| 8.4 | Time-of-day TPS-TC (ToD-TC) ..... | 51 | +| 9 | Physical media specific transmission convergence (PMS-TC) sublayer ..... | 58 | +| 9.1 | PMS-TC functional model ..... | 59 | +| 9.2 | Scrambler..... | 62 | +| 9.3 | Forward error correction ..... | 62 | +| 9.4 | Interleaving..... | 63 | +| 9.5 | Framing ..... | 64 | +| 9.6 | Impulse noise protection ( $INP_p$ ) ..... | 74 | +| 9.7 | Delay ..... | 75 | +| 9.8 | Bit error ratio (BER)..... | 75 | +| 9.9 | Delay variation ..... | 75 | +| 10 | Physical media dependent (PMD) function..... | 76 | +| 10.1 | PMD functional model ..... | 76 | +| 10.2 | DMT superframe ..... | 77 | +| 10.3 | Symbol encoder for data symbols ..... | 77 | + +| | Page | +|-------------------------------------------------------------------------|------| +| 10.4 Modulation ..... | 92 | +| 10.5 Symbol encoder for sync symbol ..... | 96 | +| 10.6 Symbol encoder for initialization ..... | 97 | +| 11 Operation and maintenance (OAM) ..... | 97 | +| 11.1 OAM functional model ..... | 97 | +| 11.2 VDSL2 management entity (VME) ..... | 99 | +| 11.3 OAM primitives ..... | 133 | +| 11.4 OAM parameters ..... | 136 | +| 11.5 Data gathering function ..... | 171 | +| 12 Link activation methods and procedures ..... | 183 | +| 12.1 Overview ..... | 183 | +| 12.2 Special operations channel (SOC) ..... | 191 | +| 12.3 Initialization procedure ..... | 195 | +| 12.4 Loop diagnostic mode procedures ..... | 286 | +| 12.5 Fast start-up ..... | 295 | +| 13 On-line reconfiguration (OLR) ..... | 295 | +| 13.1 Types of on-line reconfiguration ..... | 295 | +| 13.2 Control parameters ..... | 296 | +| 13.3 Timing of changes in subcarrier configuration ..... | 298 | +| 13.4 Receiver initiated procedure ..... | 300 | +| 14 Electrical requirements ..... | 303 | +| 14.1 Termination impedance model ..... | 303 | +| 14.2 Service splitters ..... | 303 | +| Annex A – Region A (North America) ..... | 305 | +| A.1 Band plan ..... | 305 | +| A.2 Limit PSD masks ..... | 305 | +| A.3 UPBO reference PSDs ..... | 314 | +| Annex B – Region B (Europe) ..... | 315 | +| B.1 Band plans ..... | 315 | +| B.2 Limit PSD mask options ..... | 318 | +| B.3 UPBO reference PSDs ..... | 334 | +| B.4 Template PSD ..... | 334 | +| B.5 Compliance ..... | 334 | +| Annex C – Region C (Japan) ..... | 335 | +| C.1 Band plan ..... | 335 | +| C.2 Limit PSD masks ..... | 335 | +| C.3 VDSL2 system with PSD reduction at frequencies below DPBOFMAX ..... | 344 | +| C.4 Upstream power back-off (UPBO) PSD masks ..... | 344 | +| C.5 Service Splitter ..... | 345 | + +| | Page | +|-------------------------------------------------------------------------------------------|-------------| +| C.6 Test loops and crosstalk disturbers..... | 345 | +| Annex D – Long Reach VDSL2 ..... | 347 | +| Annex E ..... | 352 | +| Annex F ..... | 352 | +| Annex G ..... | 352 | +| Annex H ..... | 352 | +| Annex J ..... | 353 | +| Annex K ..... | 353 | +| Annex L – TPS-TC functional descriptions..... | 354 | +| L.1 STM transmission convergence (STM-TC) function..... | 354 | +| L.2 ATM transmission convergence (ATM-TC) function ..... | 360 | +| L.3 Packet transmission convergence function (PTM-TC) ..... | 370 | +| Annex M – Time-of-day distribution over VDSL2 links ..... | 376 | +| M.1 Time-of-day distribution operational overview ..... | 376 | +| M.2 Definitions ..... | 376 | +| M.3 Abbreviations ..... | 376 | +| M.4 VTU functional model..... | 376 | +| M.5 TPS-TC function ..... | 376 | +| M.6 eoc communication protocol ..... | 376 | +| M.7 ToD TPS-TC (ToD-TC)..... | 376 | +| M.8 Mapping of OH data..... | 376 | +| M.9 eoc transmission protocol..... | 376 | +| M.10 Frequency synchronization command..... | 376 | +| M.11 Time synchronization command and responses ..... | 378 | +| M.12 Updates to initialization..... | 378 | +| Annex N – Region D (China) ..... | 379 | +| N.1 Band plans ..... | 379 | +| N.2 Limit PSD mask options..... | 380 | +| N.3 UPBO reference PSDs..... | 388 | +| N.4 Template PSD..... | 388 | +| N.5 Compliance..... | 388 | +| Annex O ..... | 389 | +| Annex P – Short reach VDSL2 with reduced power and enhanced data rate..... | 390 | +| P.1 Scope ..... | 390 | +| P.2 Reduced ATP ..... | 390 | +| P.3 Minimum bidirectional net data rate capability..... | 390 | +| P.4 ITU-T G.998.4 Annex D support for enhanced net data rates with ITU-T
G.998.4 ..... | 390 | + +| | Page | +|----------------------------------------------------------------------------------------------|------| +| P.5 SRA support ..... | 391 | +| P.6 TPS-TC..... | 391 | +| Annex Q – Enhanced data rate 35 MHz VDSL2 with 4.3125 kHz subcarrier spacing..... | 392 | +| Q.1 Scope ..... | 392 | +| Q.2 Capabilities related to the profile ..... | 392 | +| Q.3 ITU-T G.998.4 Annex D support for enhanced net data rates ..... | 394 | +| Q.4 SRA support ..... | 395 | +| Q.5 TPS-TC..... | 396 | +| Q.6 Additional changes to ITU-T G.993.2 for operation according to profile 35b ..... | 396 | +| Annex R ..... | 410 | +| Annex S ..... | 410 | +| Annex T ..... | 410 | +| Annex U ..... | 410 | +| Annex V ..... | 410 | +| Annex W ..... | 410 | +| Annex X – ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction ..... | 411 | +| X.1 Power management commands and responses (clause 11.2.3.9) ..... | 411 | +| X.2 Initialization procedure (supplements clause 12.3) ..... | 412 | +| Annex Y – Full ITU-T G.993.5-friendly ITU-T G.993.2 operation..... | 419 | +| Y.1 Initialization procedure (supplements clause 12.3) ..... | 419 | +| Y.2 R-MSG1 (supplements clause 10.3.2.2 of [ITU-T G.993.5]) ..... | 422 | +| Y.3 O-TA_UPDATE (supplements clause 10.4.2.1 of [ITU-T G.993.5])..... | 422 | +| Y.4 R-P-VECTOR 2 (replaces clause 10.4.4.5 of [ITU-T G.993.5]) ..... | 422 | +| Y.5 O-PMS (supplements clause 10.5.2.1 of [ITU-T G.993.5])..... | 423 | +| Y.6 eoc messages for backchannel configuration (replaces clause 8.1 of [ITU-T G.993.5])..... | 423 | +| Y.7 Loop diagnostic mode procedures (replaces clause 12.4)..... | 423 | +| Appendix I – Example values of DPBO parameters to protect ADSL2plus for clause C.3 .... | 424 | +| I.1 Example PSD parameters ..... | 424 | +| I.2 Example Cable parameters ..... | 424 | +| I.3 Example frequency parameters ..... | 425 | +| Appendix II – Impact of loop and VTU impedance mismatch on the Hlog accuracy..... | 426 | +| Bibliography ..... | 429 | + + + +## Recommendation ITU-T G.993.2 + +# Very high speed digital subscriber line transceivers 2 (VDSL2) + +# 1 Scope + +This Recommendation is an enhancement to [ITU-T G.993.1] that supports transmission at a bidirectional net data rate (the sum of upstream and downstream rates) up to 200 Mbit/s on twisted pairs. This Recommendation is an access technology that exploits the existing infrastructure of copper wires that were originally deployed for plain old telephone service (POTS). + +This Recommendation specifies only discrete multi-tone (DMT) modulation and incorporates components from [ITU-T G.993.1] (VDSL), [ITU-T G.992.3] (ADSL2), and [ITU-T G.992.5] (ADSL2 plus). + +Whilst POTS uses approximately the lowest 4 kHz and asymmetric digital subscriber line (ADSL) uses approximately 2 MHz of the copper wire spectrum, this Recommendation is defined to allow the use of up to 30 MHz of the spectrum. This Recommendation can be deployed from central offices, from fibre-fed cabinets located near the customer premises, or within buildings. + +The availability of bandwidth up to 30 MHz allows ITU-T G.993.2 transceivers to provide reliable high data rate operation on short loops. Without the use of the US0 band, this Recommendation should operate reliably over loop lengths that are similar to those of [ITU-T G.993.1], or slightly longer lengths due to the mandatory support of trellis coding. The addition of the US0 band and means to train echo cancellers and time-domain equalizers (TEQs) also allows this Recommendation to provide reliable operation on loops up to approximately 2 500 metres of 26 American wire gauge (AWG) (0.4 mm). + +This Recommendation defines a wide range of settings for various parameters (such as bandwidth and transmitter power) that could potentially be supported by a transceiver. Therefore, this Recommendation specifies profiles to allow transceivers to support a subset of the allowed settings and still be compliant with the Recommendation. The specification of multiple profiles allows vendors to limit implementation complexity and develop implementations that target specific service requirements. Some profiles are better suited for asymmetric data rate services, whereas other profiles are better for symmetric data rate services. + +The annexes of this Recommendation include band plans and power spectral density (PSD) masks that address region-specific requirements. + +Like [ITU-T G.993.1], this Recommendation defines upstream power back-off (UPBO) to mitigate far-end crosstalk (FEXT) caused by upstream transmissions on shorter loops to longer loops. The mechanism is the same as in [ITU-T G.993.1]. + +As with other ITU-T Recommendations in the ITU-T G.99x series, this Recommendation uses [ITU-T G.994.1] to initiate the transceiver training sequence. + +Changes in this Recommendation relative to [ITU-T G.993.1] include: + +- The definition of profiles to support a wide range of deployment scenarios (e.g., central offices, fibre-fed cabinets located near the customer premises, and within buildings). + +For TPS-TC sublayer specifically, changes in this Recommendation relative to [ITU-T G.993.1] include: + +- Support for STM interfaces; +- Support for PTM interfaces based on IEEE 802.3 64/65 octet encapsulation; +- Support for ToD-TC functionality for transport of time-of-day over VDSL2 links. + +For PMS-TC sublayer specifically, changes in this Recommendation relative to [ITU-T G.993.1] include: + +- Improved framing (based on [ITU-T G.992.3]); +- The definition of two latency paths and two bearer channels; +- Improved on-line reconfiguration (OLR) mechanisms (based on [ITU-T G.992.3]), including optional SRA, special operations channel (SOS), and dynamic interleaver change; +- Control of delay variation; +- Improved overhead channel; +- Improved forward error correction (FEC) capabilities, including a wider range of settings for the Reed-Solomon (RS) encoder and the interleaver; +- Improved interleaving with controlled memory-split between downstream and upstream; +- Support of all integer values of impulse noise protection (INP) up to 16 symbols; +- Optional impulse noise monitor (INM) function. + +For PMD sublayer specifically, changes in this Recommendation relative to [ITU-T G.993.1] include: + +- The definition, in annexes, of band plans up to 30 MHz to support a bidirectional net data rate up to 200 Mbit/s; +- Support for extension of the upper band edge of the US0 band to as high as 276 kHz (based on Annex M of [ITU-T G.992.3]); +- The definition of means to improve the performance of US0 (specifically, support in initialization for training of time domain equalizers and echo cancellers); +- A requirement to support the US0 band in the upstream direction for some profiles; +- Support for spectrum shaping of the US0 band in the upstream direction; +- Support for a management information base (MIB)-controlled PSD mask mechanism to enable in-band spectrum shaping (based on [ITU-T G.992.5]); +- Alternative electrical length estimation method (AELE-M1); +- Optional equalized FEXT UPBO method; +- A requirement for downstream and upstream transmitters to notch, simultaneously, 16 arbitrary operator-defined radio frequency interference (RFI) bands; +- Support for downstream maximum transmit power (profile dependent) of up to 20.5 dBm; +- Mandatory support of trellis coding (based on [ITU-T G.992.3]); +- The definition of receiver-determined tone ordering (based on [ITU-T G.992.3]); +- Mandatory support of all integer-bit constellations from 1 bit to 15 bits; +- Support for optional cyclic extension (CE) lengths as large as $\frac{1}{4}$ of a symbol period; +- Optional virtual noise (VN) mechanism; +- The definition of VTU-R receiver-selected pilot tone(s), including the option not to select a pilot tone; +- Insertion of a sync symbol after every 256 data symbols to signal OLR transitions; +- Improvements to initialization, including the definition of a channel discovery phase, a training phase, and a channel analysis and exchange phase; +- Definition of re-initialization policy parameters; +- Definition of link activation methods and procedures; +- Support for a VTU-R lineprobe stage during initialization; + +- Support for a wide range of test parameters and accuracy requirements (based on [ITU-T G.992.3]); +- The definition of a loop diagnostic mode; +- Support for an optional all-digital mode; +- Definition of downstream and full vectoring-friendly operating modes. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.117] Recommendation ITU-T G.117 (1996), *Transmission aspects of unbalance about earth.* +- [ITU-T G.992.1] Recommendation ITU-T G.992.1 (1999), *Asymmetric digital subscriber line (ADSL) transceivers.* +- [ITU-T G.992.3] Recommendation ITU-T G.992.3 (2009), *Asymmetric digital subscriber line transceivers 2 (ADSL2).* +- [ITU-T G.992.5] Recommendation ITU-T G.992.5 (2009), *Asymmetric digital subscriber line 2 (ADSL2) transceivers – Extended bandwidth ADSL2 (ADSL2 plus).* +- [ITU-T G.993.1] Recommendation ITU-T G.993.1 (2004), *Very high speed digital subscriber line transceivers (VDSL).* +- [ITU-T G.993.5] Recommendation ITU-T G.993.5 (2019), *Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers.* +- [ITU-T G.994.1] Recommendation ITU-T G.994.1 (2018), *Handshake procedures for digital subscriber line transceivers.* +- [ITU-T G.995.1] Recommendation ITU-T G.995.1 (2001), *Overview of digital subscriber line (DSL) Recommendations.* +- [ITU-T G.997.1] Recommendation ITU-T G.997.1 (2019), *Physical layer management for digital subscriber line transceivers.* +- [ITU-T G.998.4] Recommendation ITU-T G.998.4 (2018), *Improved impulse noise protection for digital subscriber line (DSL) transceivers.* +- [ITU-T G.9954] Recommendation ITU-T G.9954 (2007), *Home networking transceivers – Enhanced physical, media access, and link layer specifications.* +- [ITU-T I.361] Recommendation ITU-T I.361 (1999), *B-ISDN ATM layer specification.* +- [ITU-T I.432.1] Recommendation ITU-T I.432.1 (1999), *B-ISDN user-network interface – Physical layer specification: General characteristics.* +- [ITU-T O.9] Recommendation ITU-T O.9 (1999), *Measuring arrangements to assess the degree of unbalance about earth.* +- [ITU-T O.41] Recommendation ITU-T O.41 (1994), *Psophometer for use on telephone-type circuits.* + +- [ITU-T T.35] Recommendation ITU-T T.35 (2000), *Procedure for the allocation of ITU-T defined codes for non-standard facilities*. +- [IETF RFC 5905] IETF RFC 5905 (2010), *Network Time Protocol Version 4: Protocol and Algorithms Specification*. +- [ISO 8601] ISO 8601-1:2019, *Date and time – Representations for information interchange – Part 1: Basic rules*. + +# 3 Definitions + +This Recommendation defines the following terms: + +- 3.1 aggregate data rate:** The net data rate plus the overhead data rate in any one direction (see Table 5-1). +- 3.2 aggregate downstream (upstream) transmit power:** The power transmitted within the entire downstream (upstream) passband. +- 3.3 anomaly:** A discrepancy between the actual and desired characteristics of an item. The desired characteristics may be expressed in the form of a specification. An anomaly may or may not affect the ability of an item to perform a required function. +- 3.4 band plan:** The partitioning of the frequency spectrum into non-overlapping frequency bands, each of which is allocated for either upstream or downstream transmission. +- 3.5 bearer channel:** A data stream at a specified data rate between two TPS-TC entities (one in each VTU) that is transported transparently over a single latency path by the PMS-TC and PMD sublayers, also referred to as "frame bearer" (see Annex L). +- 3.6 bidirectional net data rate:** The sum of upstream and downstream net data rates. +- 3.7 blackout subcarrier:** A subcarrier selected by the receiver to be allocated no power by the transmitter. +- 3.8 channel:** A connection conveying signals between two blocks (the conveyed signals represent information). Channels also convey signals between a block and the environment. Channels may be unidirectional or bidirectional. +- 3.9 channel discovery PSD:** The PSD of signals transmitted by the VTU at every frequency (i.e., in both the passband and the stopbands) during the channel discovery phase of initialization. The channel discovery PSDs for the downstream and upstream directions are denoted as CDPSDds and CDPSDus, respectively. +- 3.10 connection:** An association of transmission channels or circuits, switching and other functional units set up to provide a means for a transfer of user, control and management information between two or more end points (blocks) in a telecommunication network. +- 3.11 data:** All bits or bytes transported over the channel that individually convey information. Data includes both user data and overhead bits. Data does not include bits or bytes that, by themselves, do not convey any information, such as bits in a sync frame. See also "data frame" and "data symbol". +- 3.12 data frame:** A frame composed of bits from the enabled latency paths over a single symbol time period, after the addition of FEC octets and after interleaving, which is exchanged over the $\delta$ reference point between the PMS-TC and PMD sublayers. +- 3.13 data symbol:** A DMT symbol carrying a data frame. +- 3.14 data symbol rate:** The average rate at which data symbols are transmitted (see clause 10.4.4). This is not the same as "symbol rate". + +**3.15 defect:** A limited interruption in the ability of an item to perform a required function. It may or may not lead to maintenance action depending on the results of additional analysis. Successive anomalies causing a decrease in the ability of an item to perform a required function are considered a defect. + +**3.16 DMT superframe:** A set of 256 consecutive data frames followed by one sync frame, modulated onto 257 consecutive symbols. + +**3.17 DMT symbol:** The time-domain samples emerging from the DMT modulator during one symbol period, following insertion of the cyclic extension and completion of the windowing and overlap-and-add operations. During showtime, there are two types of DMT symbols: data symbols and sync symbols. + +**3.18 downstream:** Information flow whose direction is from a service provider (operator) to a subscriber. + +**3.19 electrical length:** An estimate of the loop attenuation, assuming that all sections of a loop obey a $\sqrt{f}$ attenuation characteristic. Specifically, the electrical length is the attenuation, in dB at 1 MHz, of an equivalent hypothetical loop with a perfect $\sqrt{f}$ attenuation characteristic. + +NOTE – The attenuation caused by bridged taps does not follow a $\sqrt{f}$ characteristic, and thus the effects of bridged taps may not be accurately represented in the estimate. + +**3.20 epoch:** The origin of a timescale. + +**3.21 frame:** A general term to describe an ordered grouping of bits. See, for example, "data frame", "sync frame", and "overhead frame". + +**3.22 frame bearer:** See the definition for "bearer channel". + +**3.23 HDLC frame:** A group of data bytes encapsulated into the HDLC structure (see clause 8.2.3). + +**3.24 indicator bits:** Bits used for operations and maintenance (OAM) purposes; embedded in the overhead octets. + +**3.25 interface:** A point of demarcation between two blocks, through which information flows from one block to the other. An interface may be a physical interface or a logical interface. + +**3.26 layer/sublayer:** A collection of objects of the same hierarchical rank. + +**3.27 limit PSD mask:** A PSD mask specified in an annex of this Recommendation. The limit PSD mask is defined at all frequencies (i.e., in both the passband and the stopbands). The limit PSD masks for the downstream and upstream directions are denoted LIMITMASKds and LIMITMASKus, respectively. + +**3.28 line rate:** The data rate transmitted at the U-x reference point in any one direction. This is the total data rate plus trellis coding overhead. + +**3.29 logical (functional) interface:** An interface where the semantic, syntactic, and symbolic attributes of information flows are defined. Logical interfaces do not define the physical properties of signals used to represent the information. A logical interface can be an internal or external interface. It is defined by a set of information flows and associated protocol stacks. + +**3.30 loop timing:** A mode of operation where the VTU-R clock is extracted from the received signal. In loop timing mode, the VTU-R operates as a slave; the VTU-R transmit and receive clocks are equal to the transmit clock of the VTU-O, within the tolerance introduced by the implementation. + +**3.31 MEDLEY reference PSD:** The PSD of signals transmitted by a VTU at every frequency (i.e., in both the passband and the stopbands) during the training phase and the channel analysis and + +exchange phase of initialization. The MEDLEY reference PSDs in the downstream and upstream directions are denoted as MREFPSDds and MREFPSDus, respectively. + +**3.32 MEDLEY reference PSD mask:** The MEDLEY reference PSD mask is the transmit PSD mask limited at every frequency (i.e., in both the passband and the stopbands) by the PSD ceiling and limited to $-80$ dBm/Hz at frequencies corresponding to the designated RFI bands. In the upstream direction, the MEDLEY reference PSD mask is further reduced in accordance with the UPBO requirements. The MEDLEY reference PSD masks in the downstream and upstream directions are denoted as MREFMASKds and MREFMASKus, respectively. + +**3.33 MEDLEY set:** A subset of the SUPPORTEDCARRIERS set. It is determined during the channel discovery phase and contains the subcarriers that will be used for transmission of initialization signals after the channel discovery phase. For each subcarrier in the MEDLEY set, a $b_i$ and a $g_i$ value will be exchanged during the channel analysis and exchange phase. Blackout subcarriers are not part of the MEDLEY set. The MEDLEY set is denoted MEDLEYds and MEDLEYus, respectively, for the downstream and upstream directions. + +**3.34 message overhead data rate of latency path $p$ :** The part of the overhead data rate assigned for the message transport for latency path $p$ in any one direction of transmission (see Table 5-1). + +**3.35 MIB PSD mask:** A PSD mask specified by the operator to restrict the transmit PSD in the passband to levels below those allowed by the applicable limit PSD mask. The MIB PSD mask is defined only within the passband and lies at or below the limit PSD mask. Operators may choose not to specify a MIB PSD mask for one or both transmission directions or in specific bands of the passband. The MIB PSD masks for the downstream and upstream directions are denoted as MIBMASKds and MIBMASKus, respectively. The MIB PSD mask does not incorporate PSD requirements for RFI bands, which are specified separately (see definition of "RFI bands"). + +**3.36 monitored subcarrier:** A subcarrier (but not a pilot tone) in the MEDLEY set that has $b_i = 0$ and $g_i > 0$ . + +**3.37 mux data frame:** The grouping of octets from different bearer channels within the same latency path, after the overhead data octets have been added. + +**3.38 net data rate of bearer channel $n$ :** The data rate of a single bearer channel $n$ at the $\alpha/\beta$ interface of the user plane in any one direction of transmission (see Table 5-1). + +**3.39 net data rate of latency path $p$ :** The sum of net data rates over all bearer channels of latency path $p$ (see Table 5-1). + +**3.40 net data rate:** The sum of net data rates over all latency paths (see Table 5-1). + +**3.41 network:** A collection of interconnected elements that provide connection services to users. + +**3.42 network timing reference:** An 8-kHz timing marker used to support the distribution of a timing reference over the network. + +**3.43 overhead data rate:** The sum of overhead data rates over all latency paths (see Table 5-1). + +**3.44 overhead data rate of latency path $p$ :** The data rate of the overhead channel assigned for latency path $p$ in any one direction of transmission (see Table 5-1). + +**3.45 overhead (OH) frame:** A frame composed of a CRC byte, followed by a Syncbyte, followed by other bytes from the overhead channel (see Table 9-4). + +**3.46 overhead (OH) subframe:** A subdivision of an OH frame (see Figure 9-4). + +**3.47 overhead (OH) superframe:** A specific number of consecutive overhead frames in which the first overhead frame carries a Syncbyte of value $AC_{16}$ . The overhead superframe is not related to the DMT superframe. + +- 3.48 passband:** The portion of the frequency spectrum that is allowed to be used for transmission in one direction. The passband may consist of multiple, disjointed portions of the frequency spectrum. The upstream and downstream passbands depend on the selected band plan and profile. +- 3.49 precision time protocol (PTP):** The protocol defined by IEEE 1588-2008. +- 3.50 primitives:** Basic measures of performance, usually obtained from digital signal line codes and frame formats, or as reported in overhead indicators from the far end. Performance primitives are categorized as events, anomalies and defects. Primitives may also be basic measures of other quantities (e.g., a.c. or battery power), usually obtained from equipment indicators. +- 3.51 PSD ceiling:** The PSD level, independent of frequency (and indicated by a single value), that limits the transmit PSD mask when the MEDLEY reference PSD mask is determined. The PSD ceilings in the downstream and upstream directions are denoted as MAXMASKds and MAXMASKus, respectively. The PSD ceiling determines the transmit power cut-back and is set at the end of the channel discovery phase of initialization. Initial PSD ceilings in the downstream and upstream directions, used during the channel discovery phase of initialization, are denoted as CDMAXMASKds and CDMAXMASKus, respectively (see clause 12.3.3). +- 3.52 reference point:** A set of interfaces between any two related blocks through which information flows from one block to the other. A reference point comprises one or more logical (non-physical) information-transfer interfaces, and one or more physical signal-transfer interfaces. +- 3.53 RFI bands:** One or more operator-specified frequency bands in which the PSD transmitted by a VTU is to be no higher than $-80$ dBm/Hz. A single set of RFI bands (RFIBANDS) is specified, which applies to both downstream and upstream transmission. +- 3.54 showtime:** The state of either the VTU-O or VTU-R that is reached after the initialization procedure has been completed in which bearer channel data are transmitted. +- 3.55 splitter:** A filter that separates VDSL2 signals from the voiceband or ISDN signals (frequently called a POTS or ISDN splitter, even though the voiceband signals may comprise more than POTS). +- 3.56 subcarrier:** A fundamental element of a discrete multi-tone (DMT) modulator. The modulator partitions the channel bandwidth into a set of parallel subchannels. The centre frequency of each subchannel is a subcarrier, onto which bits may be modulated for transmission over a channel (see clause 10). +- 3.57 subcarrier group:** A grouping of $G$ (where $G = 1, 2, 4, \text{ or } 8$ ) adjacent subcarriers. Subcarrier groups are used to reduce the number of test parameter data points that need to be stored by and communicated between the VTU-O and VTU-R. Each subcarrier in a subcarrier group is characterized by the same value of a test parameter (see clause 11.4.1). +- 3.58 SUPPORTEDCARRIERS set:** The set of subcarriers allocated for transmission in one direction, as determined by the band plan and any restrictions imposed by the operator via the CO-MIB (e.g., VDSL2-CARMASK as defined in [ITU-T G.997.1]); denoted SUPPORTEDCARRIERSds and SUPPORTEDCARRIERSus, respectively, for the downstream and upstream directions. +- 3.59 symbol:** See DMT symbol. +- 3.60 symbol rate:** The rate at which DMT symbols are transmitted from the VTU-O to the VTU-R and vice versa. This is not the same as "data symbol rate". +- 3.61 sync frame:** A frame composed of all ZEROS or all ONES that is modulated onto a sync symbol as defined in clause 10.5.1. +- 3.62 sync symbol:** A DMT symbol carrying a sync frame. + +- 3.63 Syncbyte:** The second octet of each overhead frame, which indicates whether the OH frame is the first in an OH superframe. +- 3.64 Syncflag:** A sync symbol in which the sync frame bits are inverted relative to the sync frame modulated by the most recently transmitted sync symbol (i.e., if the previous sync frame was all ZEROS, the Syncflag would correspond to a sync frame of all ONES, and vice versa). The Syncflag is used to signal online reconfiguration transitions. +- 3.65 system:** A collection of interacting objects that serves a useful purpose; typically, a primary subdivision of an object of any size or composition (including domains). +- 3.66 ToD phase difference value:** The value of the VTU-x Real-time Clock modulo 125 $\mu\text{s}$ at the moment the reference sample crosses the U-x reference point (i.e., phase of $t_n$ event relative to the time-of-day, in nanoseconds, see also clause 8.4.3.2). +- 3.67 total data rate:** The aggregate data rate plus the Reed-Solomon FEC overhead rate in any one direction (see Table 5-1). +- 3.68 transmit power back-off (PBO):** Reduction of the transmitted PSD for spectral compatibility purposes, via PSD shaping using a predefined method that is dependent only on loop conditions and is independent of the service (bearer) requirements such as net data rates, INP, and delay. +- 3.69 transmit power cut-back (PCB):** Reduction of the transmitted PSD using the PSD ceiling mechanism. The PCB is dependent on the service (bearer) requirements, such as net data rates, INP, and delay, and on the desired SNR margin. The PCB also accommodates the dynamic range of the far-end receiver. +- 3.70 transmit PSD mask:** The PSD mask derived as the minimum at every frequency (i.e., in both the passband and the stopbands) of 1) the relevant Limit PSD mask; 2) the MIB PSD mask, if defined; and 3) the vendor-discretionary PSD mask restrictions imposed by the VTU-O for the downstream and upstream directions. The transmit PSD masks for the downstream and upstream directions are denoted as PSDMASKds and PSDMASKus, respectively. +- 3.71 upstream:** Information flow whose direction is from a subscriber to a service provider (operator). +- 3.72 user:** A service-consuming object or system (block). +- 3.73 voiceband:** 0 to 4 kHz; expanded from the traditional 0.3 to 3.4 kHz to deal with voiceband data services wider than POTS. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------|-------------------------------------------------------| +| ACTATP | Actual Aggregate Transmit Power | +| AGC | Automatic Gain Control | +| AN | Access Node | +| ATM | Asynchronous Transfer Mode | +| ATM-TC | Asynchronous Transfer Mode – Transmission Convergence | +| ATTNDR | Attainable Net Data Rate | +| BER | Bit Error Ratio | +| CE | Cyclic Extension | +| CPE | Customer Premises Equipment | + +| | | +|--------|------------------------------------------------| +| CRC | Cyclic Redundancy Check | +| DMT | Discrete Multi-Tone | +| DS | Downstream | +| DSL | Digital Subscriber Line | +| EC | Echo Canceller (or Cancellation) | +| EIA | External OAM Interface Adapter | +| eoc | embedded operations channel | +| FCS | Frame Check Sequence | +| FDD | Frequency Division Duplexing | +| FEC | Forward Error Correction | +| flcd-n | far-end loss of cell delineation defect | +| flpr | far-end loss of power primitive | +| GSTN | General Switched Telephone Network | +| HDLC | High-level Data Link Control | +| HPF | High-Pass Filter | +| IB | Indicator Bit | +| IDFT | Inverse Discrete Fourier Transform | +| INM | Impulse Noise Monitoring | +| INP | Impulse Noise Protection | +| INS | Impulse Noise Sensor | +| ISDN | Integrated Services Digital Network | +| lcd-n | loss of cell delineation defect | +| LATN | Loop Attenuation | +| LCL | Longitudinal Conversion Loss | +| LOF | Loss of Frame | +| lom | loss of margin defect | +| lom-fe | far-end loss of margin defect | +| LOS | Loss of Signal | +| los | loss of signal defect | +| los-fe | far-end loss of signal defect | +| LPF | Low-Pass Filter | +| lpr | loss of power | +| LSB | Least Significant Bit | +| LTR | Local Timing Reference | +| MBDC | Minimum Bidirectional net Data rate Capability | +| MDF | Mux Data Frame | +| MIB | Management Information Base | + +| | | +|------------|---------------------------------------------------------------------------------------------------------------------------------| +| MPS-TC | Management Protocol Specific – Transmission Convergence | +| MSB | Most Significant Bit | +| mux | Multiplex | +| NMS | Network Management System | +| $NSC_{us}$ | Number of Subcarriers in MEDLEYus set | +| $NSC_{ds}$ | Number of Subcarriers in MEDLEYds set | +| NSF | Non-Standard Facility | +| NT | Network Termination | +| NTR | Network Timing Reference | +| OAM | Operations, Administration and Maintenance | +| OH | Overhead | +| OLR | On-Line Reconfiguration | +| ONU | Optical Network Unit | +| PMD | Physical Media Dependent | +| PMS | Physical Media Specific | +| PMS-TC | Physical Media Specific Transmission Convergence | +| POTS | Plain Old Telephone Service; one of the services using the voiceband; sometimes used as a descriptor for all voiceband services | +| PRBS | Pseudo-Random Binary Sequence | +| PSD | Power Spectral Density | +| PTM | Packet Transfer Mode | +| PTM-TC | Packet Transfer Mode Transmission Convergence | +| QAM | Quadrature Amplitude Modulation | +| rdi | remote defect indication defect | +| RFI | Radio Frequency Interference | +| rms | root mean square | +| ROC | Robust Overhead Channel | +| RS | Reed-Solomon | +| RTC | Real-Time Clock | +| RX (Rx) | Receiver | +| SATN | Signal Attenuation | +| SAVN | Showtime Adaptive Virtual Noise | +| SC | Segment Code | +| sef | severely errored frame | +| SNR | Signal-to-Noise Ratio | +| SNRM | Signal-to-Noise Ratio Margin | +| SOC | Special Operations Channel | + +| | | +|----------|--------------------------------------------------------------------------------------------------------------| +| SOS | Save Our Showtime | +| SRA | Seamless Rate Adaptation | +| STM | Synchronous Transfer Mode | +| STM-TC | Synchronous Transfer Mode – Transmission Convergence | +| TA | Timing Advance | +| TC | Transmission Convergence | +| TCM-ISDN | Time Compression Multiplexed – Integrated Services Digital Network | +| TEQ | Time-domain Equalizer | +| ToD | Time-of-Day | +| TPS | Transport Protocol Specific | +| TPS-TC | Transport Protocol Specific – Transmission Convergence | +| TX (Tx) | Transmitter | +| UPBO | Upstream Power Back-Off | +| US | Upstream | +| VDSL | Very High Speed Digital Subscriber Line | +| VME | VDSL2 Management Entity | +| VN | Virtual Noise | +| VTU | VDSL2 Transceiver Unit | +| VTU-O | VTU at the Optical Network Unit (or central office, exchange, cabinet, etc., i.e., operator end of the loop) | +| VTU-R | VTU at the Remote site (i.e., subscriber end of the loop) | + +# 5 Reference models + +The functional, application, and protocol reference models of VDSL2 devices specified in this clause fit within the family of DSL Recommendations described in [ITU-T G.995.1]. Additionally, VDSL2 devices rely on constituent components described within [ITU-T G.997.1]. + +## 5.1 VTU functional model + +The functional model of VDSL2, which includes functional blocks and interfaces of the VDSL2 transceiver unit at the optical network unit (VTU-O) and VDSL2 transceiver unit (VTU) at the remote site (VTU-R) referenced in this Recommendation, is presented in Figure 5-1. The model illustrates the most basic functionality of VDSL2 and contains both an application-invariant section and an application-specific section. The application-invariant section consists of the physical medium dependent (PMD) sublayer and physical media specific part of the transmission convergence sublayer (PMS-TC), which are defined in clauses 10 and 9, respectively. The application-specific parts related to the user plane are defined in clause 8.1 and Annex L and are confined to the transport protocol specific – transmission convergence (TPS-TC) sublayer and application interfaces. The management protocol specific – transmission convergence (MPS-TC) is intended for management data transport and is described in clause 8.2. The VDSL2 management entity (VME) supports management data communication protocols and is described in clause 11.2. Management plane functions at higher layers are typically controlled by the operator's network management system (NMS) and are not shown in Figure 5-1. The NTR-TC supports transport of the 8 kHz network timing reference (NTR) + +to the VTU-R and is described in clause 8.3. The ToD-TC supports distribution of accurate time-of-day to the VTU-R and is described in clause 8.4. + +![Figure 5-1 – VDSL2 and VTU functional model. This block diagram illustrates the functional architecture of a VDSL2 system, divided into the VTU-O (Office side) and VTU-R (Remote side) connected by a central U interface. The VTU-O side includes functional blocks for ToD signal, 8 kHz NTR, OAM interface, and User application interfaces. The VTU-R side includes similar blocks. The central section contains the PMD (Physical Medium Data) and PMS-TC (Physical Medium Sublayer) blocks, separated by interfaces labeled delta_o, U, and delta_r. The diagram also shows various interfaces like alpha, beta, gamma_o, gamma_r, and delta. At the bottom, horizontal arrows categorize the components into 'Application specific', 'Application invariant', 'Main body and annexes', and 'Unspecific'.](08a978a124d3ed6cf1a3d0cfd89418d0_img.jpg) + +G.993.2(15)\_F5-1 + +Figure 5-1 – VDSL2 and VTU functional model. This block diagram illustrates the functional architecture of a VDSL2 system, divided into the VTU-O (Office side) and VTU-R (Remote side) connected by a central U interface. The VTU-O side includes functional blocks for ToD signal, 8 kHz NTR, OAM interface, and User application interfaces. The VTU-R side includes similar blocks. The central section contains the PMD (Physical Medium Data) and PMS-TC (Physical Medium Sublayer) blocks, separated by interfaces labeled delta\_o, U, and delta\_r. The diagram also shows various interfaces like alpha, beta, gamma\_o, gamma\_r, and delta. At the bottom, horizontal arrows categorize the components into 'Application specific', 'Application invariant', 'Main body and annexes', and 'Unspecific'. + +**Figure 5-1 – VDSL2 and VTU functional model** + +The principal functions of the PMD are symbol timing generation and recovery, encoding and decoding, and modulation and demodulation. The PMD may also include echo cancellation and line equalization. + +The PMS-TC sublayer contains framing and frame synchronization functions, as well as forward error correction (FEC), error detection, interleaving and de-interleaving, scrambling and descrambling functions. Additionally, the PMS-TC sublayer provides an overhead channel that is used to transport management data (control messages generated by the VME). + +The PMS-TC is connected to the PMD across the $\delta$ interface, and is connected to the TPS-TC across $\alpha$ and $\beta$ interfaces in the VTU-O and the VTU-R, respectively. + +The TPS-TC is application specific and is mainly intended to convert applicable data transport protocols into the unified format required at the $\alpha$ and $\beta$ interfaces and to provide bit rate adaptation between the user data and the data link established by the VTU. Depending on the specific application, the TPS-TC sublayer may support one or more channels of user data. The TPS-TC communicates with the user data interface blocks at the VTU-R and VTU-O across the $\gamma_R$ and $\gamma_O$ interfaces, respectively. The definition of the data interface blocks is beyond the scope of this Recommendation. + +The MPS-TC, NTR-TC, and ToD-TC provide TPS-TC functions for management data, 8 kHz NTR signals, and ToD signal, respectively. + +The VME function facilitates the management of the VTU. It communicates with higher management layer functions in the management plane as described in [ITU-T G.997.1], e.g., the NMS controlling the CO-MIB. Management information is exchanged between the VME functions of the VTU-O and VTU-R through the overhead channel provided by the PMS-TC. The MPS-TC converts the incoming management data into the unified format required at the $\alpha$ and $\beta$ interfaces to be multiplexed into the PMS-TC. The management information contains indications of anomalies and defects, and related performance monitoring counters, and management command/response messages facilitating procedures defined for use by higher layer functions, specifically for testing purposes. + +The $\alpha$ , $\beta$ , $\gamma_R$ and $\gamma_O$ interfaces are only intended as logical separations and are defined as a set of functional primitives; they are not expected to be physically accessible. Concerning the user data plane, the $\gamma_R$ and $\gamma_O$ interfaces are logically equivalent, respectively, to the T and V interfaces shown in Figure 5-4. + +## 5.2 User plane protocol reference model + +The user plane protocol reference model is shown in Figure 5-2 and corresponds to the VDSL2 functional model shown in Figure 5-1. The user plane protocol reference model is included to emphasize the layered nature of this Recommendation and to provide a view that is consistent with the generic xDSL protocol reference model shown in [ITU-T G.995.1]. + +![Figure 5-2 – User plane protocol reference model. This diagram illustrates the layered protocol stack for the user plane. On the left (VTU-O side), layers include Transport protocols (e.g., ATM), TPS-TC, PMS-TC, and PMD. On the right (VTU-R side), layers include Transport protocols (e.g., ATM), TPS-TC, PMS-TC, and PMD. The layers are separated by logical interfaces: \gamma_O, \alpha, \beta, \delta_O, \delta_R, and \gamma_R. The central 'Physical TP media' is shown between the PMD layers. External interfaces include 'LT' (LT internal interface) on the far left, 'VTU-O' and 'VTU-R' (NT1, NT1/2) at the top, and 'User data interface' (U/S/T) on the far right. A label 'G.993.2_F05-2' is present in the bottom right corner.](d9c0a780cd22626253dab4aa41699e2f_img.jpg) + +Figure 5-2 – User plane protocol reference model. This diagram illustrates the layered protocol stack for the user plane. On the left (VTU-O side), layers include Transport protocols (e.g., ATM), TPS-TC, PMS-TC, and PMD. On the right (VTU-R side), layers include Transport protocols (e.g., ATM), TPS-TC, PMS-TC, and PMD. The layers are separated by logical interfaces: $\gamma_O$ , $\alpha$ , $\beta$ , $\delta_O$ , $\delta_R$ , and $\gamma_R$ . The central 'Physical TP media' is shown between the PMD layers. External interfaces include 'LT' (LT internal interface) on the far left, 'VTU-O' and 'VTU-R' (NT1, NT1/2) at the top, and 'User data interface' (U/S/T) on the far right. A label 'G.993.2\_F05-2' is present in the bottom right corner. + +Figure 5-2 – User plane protocol reference model + +Table 5-1 summarizes the data rate terminology and definitions applicable at various reference points. The reference points refer to those shown in the reference model in Figure 5-2 and the PMS-TC functional model in Figure 9-1. + +Table 5-1 – Data rate terminology and definitions + +| Data rate | Notation/equation | Refer to | Reference point | +|-------------------------------------------------------------|---------------------------|-----------|---------------------------------------| +| Net data rate for bearer channel $n$ (of latency path $p$ ) | $NDR_{pn}$ | Table 9-8 | $\alpha$ , $\beta$ (user plane) | +| Net data rate for latency path $p$ | $NDR_p = \sum_n NDR_{pn}$ | Table 9-8 | $\alpha$ , $\beta$ (user plane) | +| Net data rate | $\sum_p NDR_p$ | – | $\alpha$ , $\beta$ (user plane) | +| Overhead data rate for latency path $p$ | $OR_p$ | Table 9-8 | $\alpha$ , $\beta$ (management plane) | + +**Table 5-1 – Data rate terminology and definitions** + +| Data rate | Notation/equation | Refer to | Reference point | +|---------------------------------------------------------------------------------------------------------------------------|----------------------------------------------|---------------------------|------------------------------------| +| Overhead data rate | $\sum_p OR_p$ | Table 9-8 | $\alpha, \beta$ (management plane) | +| Message overhead data rate for latency path p | $msg_p$ | Table 9-8 | $\alpha, \beta$ (management plane) | +| Aggregate data rate for latency path p
= net data rate for latency path p
+ overhead data rate for latency path p | $NDR_p + OR_p$ | Table 9-8, clause 9.1 | A | +| Aggregate data rate
= net data rate + overhead data rate | $\sum_p NDR_p + OR_p$ | Table 9-8, clause 9.1 | A | +| Total data rate for latency path p
= aggregate data rate for latency path p
+ RS coding overhead for latency path p | $TDR_p = L_p \times f_s$ | Table 9-8, clause 9.1 | C | +| Total data rate
= aggregate data rate + RS coding overhead | $TDR = \left( \sum_p L_p \right) \times f_s$ | Table 9-8, clause 9.1 | $\delta$ | +| Line rate
= total data rate + trellis coding overhead rate | $\left( \sum_i b_i \right) \times f_s$ | Clauses 10.3.3 and 10.4.4 | U | +| Bidirectional net data rate (related to MBDC) | $\sum_p NDR_{DS_p} + \sum_p NDR_{US_p}$ | Table 9-8 | $\alpha, \beta$ (user plane) | + +## 5.3 Management plane reference model + +The management plane protocol reference model is shown in Figure 5-3 and corresponds to the VDSL2 functional model shown in Figure 5-1. The management plane protocol reference model relates specifically to the transport of management data through the VDSL2 link. + +![Figure 5-3 – Management plane protocol reference model diagram showing the protocol stack for VTU-O and VTU-R connected via an OAM interface and Physical TP media.](4b87467ad9642943235f48f7d4b59449_img.jpg) + +The diagram illustrates the management plane protocol reference model. It shows two main entities, VTU-O (left) and VTU-R (right), connected via an OAM interface and a Physical TP media. The protocol stack for both VTU-O and VTU-R consists of the following layers from top to bottom: Management protocol (G.997.1), Transport protocol (VME), MPS-TC, PMS-TC, and PMD. The OAM interface is shown between the Transport protocol (VME) and the Physical TP media. Various reference points are indicated: $\gamma_{m-O}$ and $\gamma_{m-R}$ at the Transport protocol (VME) layer; $\alpha$ and $\beta$ at the MPS-TC layer; $\delta_o$ and $\delta_R$ at the PMS-TC layer. The Physical TP media is shown at the bottom, with a 'U' reference point below it. On the far left, an 'Internal interface' is shown, labeled 'Not specified' and 'LT management interface (not specified)'. On the far right, a 'User interface' is shown, labeled 'Not specified' and 'NT management interface (not specified)'. + +Figure 5-3 – Management plane protocol reference model diagram showing the protocol stack for VTU-O and VTU-R connected via an OAM interface and Physical TP media. + +**Figure 5-3 – Management plane protocol reference model** + +## 5.4 Application reference models + +The application models for VDSL2 are based on the generic reference configuration described in clause 6.1 of [ITU-T G.995.1]. There are three separate application models: + +- 1) Data service only; +- 2) Data service with underlying POTS service; and +- 3) Data service with underlying integrated services digital network (ISDN) service. + +The application reference model for remote deployment with POTS or ISDN service facilitated by a splitter is shown in Figure 5-4. The application model for splitterless remote deployment is shown in Figure 5-5. An optional low-pass filter may be included to provide additional isolation between the VTU-R and narrow-band network customer premises equipment (CPE) such as telephone sets, voiceband modems, or ISDN terminals. + +The location of the filters (high-pass filter (HPF) and low-pass filter (LPF)) in application models presented in Figures 5-4 and 5-5 is functional only; the physical location and specific characteristics of splitters and the filter may be regionally specific. The filters at the CPE side shown in Figure 5-4 may be implemented in a variety of ways, including splitters, and in-line filters, and filters integrated with VTU devices, and filters integrated with narrow-band network CPE. + +![Figure 5-4: Generic application reference model for remote deployment with splitter. The diagram shows a Broadband network connected to an AN (Access Network) containing a PH (Power Handling) unit, a VTU-O (VDSL Transceiver Unit - Office side), and a Splitter O (containing HPF and LPF). The AN is connected to a Copper pair via interface U-O 2. The Copper pair is connected to a VTU-R (VDSL Transceiver Unit - Remote side) via interface U-R 2. The VTU-R is connected to a Splitter R (containing HPF and LPF), which is connected to a Home network and a Customer premises wiring. The Customer premises wiring is connected to a Telephone set, voiceband modem, or ISDN terminal. The diagram also shows a Narrow-band network connected to the AN via GSTN or ISDN. A legend indicates that solid lines represent signal lines and dashed lines represent interfaces. The text 'G.993.2_F05-4' is in the bottom right corner, and 'CP wiring carries POTS or ISDN service' is noted below the Customer premises wiring.](a0739aaf13fa5a632d4faa830f6b2708_img.jpg) + +Figure 5-4: Generic application reference model for remote deployment with splitter. The diagram shows a Broadband network connected to an AN (Access Network) containing a PH (Power Handling) unit, a VTU-O (VDSL Transceiver Unit - Office side), and a Splitter O (containing HPF and LPF). The AN is connected to a Copper pair via interface U-O 2. The Copper pair is connected to a VTU-R (VDSL Transceiver Unit - Remote side) via interface U-R 2. The VTU-R is connected to a Splitter R (containing HPF and LPF), which is connected to a Home network and a Customer premises wiring. The Customer premises wiring is connected to a Telephone set, voiceband modem, or ISDN terminal. The diagram also shows a Narrow-band network connected to the AN via GSTN or ISDN. A legend indicates that solid lines represent signal lines and dashed lines represent interfaces. The text 'G.993.2\_F05-4' is in the bottom right corner, and 'CP wiring carries POTS or ISDN service' is noted below the Customer premises wiring. + +**Figure 5-4 – Generic application reference model for remote deployment with splitter** + +![Figure 5-5: Generic application reference model for splitterless remote deployment. The diagram shows a Broadband network connected to an Access Node (AN) via a PHY and cross-connect. The AN contains a VTU-O connected to a U-O 2 interface. A Narrow-band network (GSTN or ISDN) is connected to the AN via a Splitter O containing HPF and LPF filters. The U-O 2 interface connects to a Copper pair, which also connects to a Customer premises wiring. The Copper pair is labeled with U-O and U-R interfaces. The Customer premises wiring connects to an optional LPF filter, which then connects to a Telephone set, voiceband modem, or ISDN terminal. The Copper pair also connects to a Network Terminal (NT) containing a VTU-R, HPF, and PHY. The NT is connected to a Home network via an S/T interface, which in turn connects to two CPE devices. A note indicates that CP wiring carries POTS or ISDN and ADSL service. The diagram is labeled G.993.2_F05-5.](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg) + +Figure 5-5: Generic application reference model for splitterless remote deployment. The diagram shows a Broadband network connected to an Access Node (AN) via a PHY and cross-connect. The AN contains a VTU-O connected to a U-O 2 interface. A Narrow-band network (GSTN or ISDN) is connected to the AN via a Splitter O containing HPF and LPF filters. The U-O 2 interface connects to a Copper pair, which also connects to a Customer premises wiring. The Copper pair is labeled with U-O and U-R interfaces. The Customer premises wiring connects to an optional LPF filter, which then connects to a Telephone set, voiceband modem, or ISDN terminal. The Copper pair also connects to a Network Terminal (NT) containing a VTU-R, HPF, and PHY. The NT is connected to a Home network via an S/T interface, which in turn connects to two CPE devices. A note indicates that CP wiring carries POTS or ISDN and ADSL service. The diagram is labeled G.993.2\_F05-5. + +**Figure 5-5 – Generic application reference model for splitterless remote deployment** + +NOTE 1 – The U-O and U-R interfaces are fully defined in this Recommendation. The V and T interfaces are defined only in terms of logical functions, not physical implementations. The S/T interface is not defined in this Recommendation. + +NOTE 2 – Implementation of the V and T interfaces is optional when interfacing elements are integrated into a common element. + +NOTE 3 – One or both of the high-pass filters, which are part of the splitters, may be integrated into the VTU. If so, the U-O2 and U-R2 interfaces become the same as the U-O and U-R interfaces, respectively. + +NOTE 4 – More than one type of T interface may be defined, and more than one type of S/T interface may be provided from a VDSL2 NT (e.g., NT1 or NT2 types of functionalities). + +NOTE 5 – Specifications for service splitters (Splitter O) are found in clause 14.2. Further specifications may also be found in regional annexes (see for example Annex C.3). + +NOTE 6 – The low-pass filter shown at the customer premises in Figure 5-5 is also known as an in-line filter. In-line filter characteristics are outside the scope of this Recommendation, and are typically specified by regional standards bodies. + +NOTE 7 – VDSL2 operating in the splitterless remote deployment mode is highly likely to suffer severe service impairments due to the topology and uncertain quality of the in-premises wiring. Star topology wiring practices, in particular, will lead to deep notches in the frequency response of the transmission path due to multiple signal reflections. In addition, poor balance, routing close to sources of electrical noise, and exposure to strong radio signals can all lead to high levels of RFI. + +NOTE 8 – The access node (AN) consists of the VTU-O, the cross-connect (which includes switching and interworking functions for connection to the broadband network), and the physical interface to the broadband network (labelled PHY in Figures 5-4 and 5-5). The network terminal (NT) consists of the VTU-R, the cross-connect (which includes the switching and interworking functions for connection to the home network), and the physical interfaces to the home network (labelled PHY in Figures 5-4 and 5-5). This Recommendation only addresses the definition of the VTU-O and VTU-R. + +### 5.4.1 Data service + +To provide data-only service, VDSL2 may be operated in all-digital mode, without leaving any bandwidth for an underlying service. A data-only service may also be provided by a VDSL2 system that leaves bandwidth for underlying POTS or ISDN service, even if there is no underlying service. + +Figure 5-6 illustrates the typical application model for delivering data service over VDSL2. The VTU-R is part of the VDSL2 NT, which is typically connected to one or more user terminals, and which may include data terminals, telecommunications equipment, or other devices; these connections are designated by S/T reference points. The connection between the VTU-R and VTU-O + +is through a copper pair, with the customer premises endpoint designated as the U-R reference point and the network endpoint designated as the U-O reference point. The VTU-O is a part of the access node (AN), which is typically connected to a broadband access network at the V reference point. In this application model, there is no underlying narrow-band service carried on the same copper pair as VDSL2. + +![Figure 5-6: Data service application model. This diagram shows a network architecture where a CO network connects to an AN (Access Node) at the V reference point. The AN contains a VTU-O (VDSL2 Transceiver Unit - Office side) which connects to a Copper pair at the U-O reference point. The Copper pair connects to an NT (Network Terminal) at the U-R reference point. The NT contains a VTU-R (VDSL2 Transceiver Unit - Remote side) which connects to multiple User terminals via S/T reference points. The User terminals are grouped in a dashed box labeled (Optional). The diagram is labeled G.993.3_F05-6.](043e64d41a3368d138ace3816fd26469_img.jpg) + +Figure 5-6: Data service application model. This diagram shows a network architecture where a CO network connects to an AN (Access Node) at the V reference point. The AN contains a VTU-O (VDSL2 Transceiver Unit - Office side) which connects to a Copper pair at the U-O reference point. The Copper pair connects to an NT (Network Terminal) at the U-R reference point. The NT contains a VTU-R (VDSL2 Transceiver Unit - Remote side) which connects to multiple User terminals via S/T reference points. The User terminals are grouped in a dashed box labeled (Optional). The diagram is labeled G.993.3\_F05-6. + +**Figure 5-6 – Data service application model** + +### 5.4.2 Data with POTS service + +The typical application model for delivering data service over VDSL2 with an underlying POTS service on the same copper pair is illustrated in Figure 5-7 (remote deployment with splitter). The VTU-R is part of the VDSL2 NT that typically connects to one or more user terminals, which may include data terminals, telecommunications equipment, or other devices. These connections are designated by S/T reference points. The VTU-R is separated from the narrow-band devices by a combination of an HPF and an LPF. One or more narrow-band devices (POTS telephones, telephone answering devices, voiceband analogue modems, or other devices) are also part of the application model at the customer premises. In remote deployments with a splitter, the narrow-band devices are connected to the U-R reference point through a common low-pass filter element. + +![Figure 5-7: Data with POTS service application model for remote deployment with splitter. This diagram shows a network architecture where a CO broadband network connects to an AN (Access Node) at the V reference point. The AN contains a VTU-O (VDSL2 Transceiver Unit - Office side) which connects to a Copper pair at the U-O reference point. The VTU-O also connects to a GSTN (Global Switched Telephone Network) through an LPF (Low-Pass Filter). The Copper pair connects to an NT (Network Terminal) at the U-R reference point. The NT contains a VTU-R (VDSL2 Transceiver Unit - Remote side) which connects to multiple User terminals via S/T reference points. The User terminals are grouped in a dashed box labeled (Optional). The VTU-R is also connected to a Voice terminal through an HPF (High-Pass Filter) and an LPF (Low-Pass Filter). The Voice terminal is also grouped in a dashed box labeled (Optional). The diagram is labeled G.993.2_F05-7.](4cde160bcc69b7b6c81b648dd0e4252e_img.jpg) + +Figure 5-7: Data with POTS service application model for remote deployment with splitter. This diagram shows a network architecture where a CO broadband network connects to an AN (Access Node) at the V reference point. The AN contains a VTU-O (VDSL2 Transceiver Unit - Office side) which connects to a Copper pair at the U-O reference point. The VTU-O also connects to a GSTN (Global Switched Telephone Network) through an LPF (Low-Pass Filter). The Copper pair connects to an NT (Network Terminal) at the U-R reference point. The NT contains a VTU-R (VDSL2 Transceiver Unit - Remote side) which connects to multiple User terminals via S/T reference points. The User terminals are grouped in a dashed box labeled (Optional). The VTU-R is also connected to a Voice terminal through an HPF (High-Pass Filter) and an LPF (Low-Pass Filter). The Voice terminal is also grouped in a dashed box labeled (Optional). The diagram is labeled G.993.2\_F05-7. + +**Figure 5-7 – Data with POTS service application model for remote deployment with splitter** + +Figure 5-8 shows a splitterless remote deployment. In splitterless remote deployments, the narrow-band devices may be connected to the U-R reference point either directly, or through an LPF per device. + +The VTU-O is a part of the AN, which is typically connected to a broadband access network at the V reference point. The VTU-O is connected to the U-O reference point through an HPF; an LPF attached at the U-O reference point isolates the VTU-O from the general switched telephone network (GSTN) network. + +![Figure 5-8: Data with POTS service application model for splitterless remote deployment. The diagram shows a network architecture starting from a CO broadband network at the V reference point, connected to an AN containing a VTU-O. The VTU-O is connected to the U-O2 reference point, which is then connected to an HPF. The HPF output is at the U-O reference point. From U-O, a LPF connects to the GSTN network, and the main path continues as a copper pair. At the U-R reference point, an HPF is used. The HPF output is at the U-R2 reference point, which connects to an NT containing a VTU-R. The VTU-R is connected to multiple user terminals via S/T reference points (one shown, others optional). The VTU-R is also connected to multiple voice terminals via LPF filters (one shown, others optional). The diagram is labeled G.993.2_F05-8.](d17aa1fcc3b86503ad1dd0717a6c34c2_img.jpg) + +Figure 5-8: Data with POTS service application model for splitterless remote deployment. The diagram shows a network architecture starting from a CO broadband network at the V reference point, connected to an AN containing a VTU-O. The VTU-O is connected to the U-O2 reference point, which is then connected to an HPF. The HPF output is at the U-O reference point. From U-O, a LPF connects to the GSTN network, and the main path continues as a copper pair. At the U-R reference point, an HPF is used. The HPF output is at the U-R2 reference point, which connects to an NT containing a VTU-R. The VTU-R is connected to multiple user terminals via S/T reference points (one shown, others optional). The VTU-R is also connected to multiple voice terminals via LPF filters (one shown, others optional). The diagram is labeled G.993.2\_F05-8. + +**Figure 5-8 – Data with POTS service application model for splitterless remote deployment** + +NOTE 1 – The low-pass filters shown at the customer premises in Figure 5-8 are also known as in-line filters. In-line filter characteristics are outside the scope of this Recommendation, and are typically specified by regional standards bodies. + +NOTE 2 – VDSL2 operating in the splitterless remote deployment mode is highly likely to suffer severe service impairments due to the topology and uncertain quality of the in-premises wiring. Star topology wiring practices, in particular, will lead to deep notches in the frequency response of the transmission path due to multiple signal reflections. In addition, poor balance, routing close to sources of electrical noise, and exposure to strong radio signals can all lead to high levels of RFI. + +### 5.4.3 Data with ISDN service + +Figure 5-9 illustrates the typical application model for delivering data service over VDSL2 with an underlying ISDN service on the same copper pair. The VTU-R is part of the VDSL2 NT that typically connects to one or more user terminals, which may include data terminals, telecommunications equipment, or other devices; these connections are designated by S/T reference points. The VTU-R is separated from the copper pair by an HPF. The ISDN NT at the customer premises is separated from the copper pair by an LPF. One or more voiceband or ISDN terminals (e.g., POTS or ISDN telephones, telephone answering devices, voiceband analogue modems, or other devices) are connected to the ISDN NT. + +The VTU-O is a part of the AN, which is typically connected to a broadband access network at the V reference point. The VTU-O is connected to the U-O reference point through an HPF; an LPF attached at the U-O reference point isolates the VTU-O from the ISDN network. + +![Figure 5-9 – Data with ISDN service application model. This block diagram shows a VDSL2 system architecture. On the left, a 'CO broadband network' connects to an 'AN' (Access Network) via a 'V' interface. The 'AN' contains a 'VTU-O' (VDSL2 Transceiver Unit - Office) connected to 'U-O2' and 'U-O' interfaces. The 'U-O' interface connects to a 'Copper pair'. Along the copper pair, there are 'HPF' (High Pass Filter) and 'LPF' (Low Pass Filter) components at both ends. At the remote end, the 'Copper pair' connects to an 'NT' (Network Termination) via 'U-R2' and 'U-R' interfaces. The 'NT' contains a 'VTU-R' (VDSL2 Transceiver Unit - Remote). The 'VTU-R' is connected to 'S/T' interfaces for 'User terminal' (optional) and 'S/T/R' interfaces for 'Voice terminal' (optional). An 'ISDN' connection is shown entering the 'AN' and passing through an 'LPF' to the 'Copper pair'. An 'ISDN-NT' is also shown connected to the 'LPF' on the copper pair side. The diagram is labeled 'G.993.2_F05-9'.](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg) + +Figure 5-9 – Data with ISDN service application model. This block diagram shows a VDSL2 system architecture. On the left, a 'CO broadband network' connects to an 'AN' (Access Network) via a 'V' interface. The 'AN' contains a 'VTU-O' (VDSL2 Transceiver Unit - Office) connected to 'U-O2' and 'U-O' interfaces. The 'U-O' interface connects to a 'Copper pair'. Along the copper pair, there are 'HPF' (High Pass Filter) and 'LPF' (Low Pass Filter) components at both ends. At the remote end, the 'Copper pair' connects to an 'NT' (Network Termination) via 'U-R2' and 'U-R' interfaces. The 'NT' contains a 'VTU-R' (VDSL2 Transceiver Unit - Remote). The 'VTU-R' is connected to 'S/T' interfaces for 'User terminal' (optional) and 'S/T/R' interfaces for 'Voice terminal' (optional). An 'ISDN' connection is shown entering the 'AN' and passing through an 'LPF' to the 'Copper pair'. An 'ISDN-NT' is also shown connected to the 'LPF' on the copper pair side. The diagram is labeled 'G.993.2\_F05-9'. + +**Figure 5-9 – Data with ISDN service application model** + +# 6 Profiles + +## 6.1 Definition + +This Recommendation defines a wide range of settings for various parameters that could potentially be supported by a VDSL2 transceiver. Profiles are specified to allow transceivers to support a subset of the allowed settings and still be compliant with this Recommendation. The specification of multiple profiles allows vendors to limit implementation complexity and develop implementations that target specific service requirements. + +VDSL2 transceivers compliant with this Recommendation shall comply with at least one profile specified in this Recommendation. Compliance with more than one profile is allowed. In addition to complying with at least one profile, VDSL2 transceivers shall comply with at least one annex specifying spectral characteristics (see Annexes A, B and C). + +The eight VDSL2 profiles (8a, 8b, 8c, 8d, 12a, 12b, 17a, and 30a) are defined in Table 6-1. + +NOTE – Some parameter values are dependent on the applicable frequency plan. Explicit definitions of the parameters are provided in clauses 3 and 6.2. + +**Table 6-1 – VDSL2 profiles** + +| Frequency plan | Parameter | Parameter value for profile (Note 5) | | | | | | | | +|----------------|---------------------------------------------------|--------------------------------------|-------------------|-------------------|-------------------|-------------------|-------------------|-------------------|-------------------| +| | | 8a | 8b | 8c | 8d | 12a | 12b | 17a | 30a | +| All | Maximum aggregate downstream transmit power (dBm) | +17.5 | +20.5 | +11.5 | +14.5 | +14.5 | +14.5 | +14.5 | +14.5 | +| All | Minimum aggregate downstream transmit power (dBm) | For further study | For further study | For further study | For further study | For further study | For further study | For further study | For further study | + +**Table 6-1 – VDSL2 profiles** + +| Frequency plan | Parameter | Parameter value for profile (Note 5) | | | | | | | | +|----------------|----------------------------------------------------------------------------------------------------------------|--------------------------------------|-------------------|-------------------|-------------------|-------------------|--------------------------|--------------------------|-------------------| +| | | 8a | 8b | 8c | 8d | 12a | 12b | 17a | 30a | +| All | Maximum aggregate upstream transmit power (dBm) | +14.5 | +14.5 | +14.5 | +14.5 | +14.5 | +14.5 | +14.5 | +14.5 | +| All | Minimum aggregate upstream transmit power (dBm) | For further study | For further study | For further study | For further study | For further study | For further study | For further study | For further study | +| All | Subcarrier spacing (kHz) | 4.3125 | 4.3125 | 4.3125 | 4.3125 | 4.3125 | 4.3125 | 4.3125 | 8.625 | +| All | Support of upstream band zero (US0) | Required | Required | Required | Required | Required | Regional annex dependent | Regional annex dependent | Not Supported | +| All | Minimum bidirectional net data rate capability (MBDC) | 50 Mbit/s | 50 Mbit/s | 50 Mbit/s | 50 Mbit/s | 68 Mbit/s | 68 Mbit/s | 100 Mbit/s | 200 Mbit/s | +| All | Aggregate interleaver and de-interleaver delay (octets) | 65 536 | 65 536 | 65 536 | 65 536 | 65 536 | 65 536 | 98 304 | 131 072 | +| All | Maximum interleaving depth ( Dmax ) | 2 048 | 2 048 | 2 048 | 2 048 | 2 048 | 2 048 | 3 072 | 4 096 | +| All | Parameter (1/ S ) max downstream | 24 | 24 | 24 | 24 | 24 | 24 | 48 | 28 | +| All | Parameter (1/ S ) max upstream | 12 | 12 | 12 | 12 | 24 | 24 | 24 | 28 | +| Annex A (998) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 971
(8.5) | 1 971
(8.5) | 1 971
(8.5) | 1 971
(8.5) | 1 971
(8.5) | 1 971
(8.5) | 4 095
(17.660) | 2 666
(23) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 205
(5.2) | 1 205
(5.2) | 1 205
(5.2) | 1 205
(5.2) | 2 782
(12) | 2 782
(12) | 2 782
(12) | 3 478
(30) | + +**Table 6-1 – VDSL2 profiles** + +| Frequency plan | Parameter | Parameter value for profile (Note 5) | | | | | | | | +|-------------------|----------------------------------------------------------------------------------------------------------------|--------------------------------------|-------------|-------------|-------------|-------------|-------------|----------------|----------------| +| | | 8a | 8b | 8c | 8d | 12a | 12b | 17a | 30a | +| Annex B (998E) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 4 095 (17.660) | 3 478 (30) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 2 782 (12) | 2 782 (12) | 3 246 (14) | 2 885 (24.890) | +| Annex B (998 ADE) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 4 095 (17.660) | 2 885 (24.890) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 2 782 (12) | 2 782 (12) | 2 782 (12) | 3 478 (30) | + +**Table 6-1 – VDSL2 profiles** + +| Frequency plan | Parameter | Parameter value for profile (Note 5) | | | | | | | | +|----------------|----------------------------------------------------------------------------------------------------------------|--------------------------------------|---------------|--------------|---------------|--------------|--------------|----------------|--------------| +| | | 8a | 8b | 8c | 8d | 12a | 12b | 17a | 30a | +| Annex B (997E) | Index of highest supported downstream subcarrier (upper band edge frequency in MHz (informative)) | 1 634 (7.05) | 1 634 (7.05) | 1 634 (7.05) | 1 634 (7.05) | 1 634 (7.05) | 1 634 (7.05) | 3 246 (14) | 3 130 (27) | +| | Index of highest supported upstream subcarrier (upper band edge frequency in MHz (informative)) | 2 047 (8.832) | 2 047 (8.832) | 1 182 (5.1) | 2 047 (8.832) | 2 782 (12) | 2 782 (12) | 4 095 (17.660) | 3 478 (30) | +| Annex C | Index of highest supported downstream subcarrier (upper band edge frequency in MHz (informative)) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 4 095 (17.660) | 2 098 (18.1) | +| | Index of highest supported upstream subcarrier (upper band edge frequency in MHz (informative)) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 2 782 (12) | 2 782 (12) | 2 782 (12) | 3 478 (30) | +| Annex N (CN17) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 1 971 (8.5) | 2 782 (12) | 2 782 (12) | 3 292 (14.197) | – | + +**Table 6-1 – VDSL2 profiles** + +| Frequency plan | Parameter | Parameter value for profile (Note 5) | | | | | | | | +|----------------|--------------------------------------------------------------------------------------------------------------|--------------------------------------|-------------|-------------|-------------|-------------|-------------|----------------|-----| +| | | 8a | 8b | 8c | 8d | 12a | 12b | 17a | 30a | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 1 205 (5.2) | 4 095 (17.660) | – | + +NOTE 1 – The minimum aggregate transmit power values are for further study. These values may be provided in a later version of this Recommendation based on a consensus understanding of the power required to meet service objectives and practical implementation of line drivers. + +NOTE 2 – The allowed frequency band is determined by applicable PSD mask requirements defined in the annexes of this Recommendation, constrained by the capabilities guaranteed by the profile(s) that the implementation supports. + +NOTE 3 – The US0 frequency allocation is determined by applicable PSD mask requirements defined in the annexes to this Recommendation. + +NOTE 4 – $D_{max}$ is derived from the aggregate interleaver and de-interleaver delay by dividing this amount by 32. + +NOTE 5 – The profile 35b is defined in Annex Q. + +## 6.2 Profile parameter definitions + +Each profile specifies normative values for the following parameters: + +- The maximum aggregate transmit power in the downstream and upstream directions; +- The minimum aggregate transmit power in the downstream and upstream directions; +- The subcarrier spacing; +- Whether support of upstream band zero (US0) is required; +- The minimum bidirectional net data rate capability (MBDC); +- The aggregate interleaver and de-interleaver delay in octets; +- The index of the highest data-bearing subcarrier supported in the downstream and upstream directions (frequency plan dependent); +- Maximum interleaving depth; and +- Parameter $(1/S)_{max}$ . + +These parameters are explicitly defined in the following clauses. + +### 6.2.1 Maximum aggregate downstream transmit power + +To be compliant with a specific profile, the aggregate downstream transmit power of a VTU shall not exceed the value specified in the row labelled "maximum aggregate downstream transmit power" in Table 6-1. + +### 6.2.2 Minimum aggregate downstream transmit power + +For further study. + +### 6.2.3 Maximum aggregate upstream transmit power + +To be compliant with a specific profile, the aggregate upstream transmit power of a VTU shall not exceed the value specified in the row labelled "maximum aggregate upstream transmit power" in Table 6-1. + +### 6.2.4 Minimum aggregate upstream transmit power + +For further study. + +### 6.2.5 Required subcarrier spacing + +The subcarrier spacing is defined in clause 10.4.2. To be compliant with a profile, a VTU shall support the required subcarrier spacing specified in that profile. + +### 6.2.6 Support of upstream band zero (US0) + +This parameter specifies whether a compliant VTU is required to support upstream band zero (US0). A VTU-O compliant with a profile mandating support of US0 shall be capable of receiving US0. A VTU-R compliant with a profile mandating support of US0 shall be capable of transmitting US0. + +If US0 is not supported, US0 shall be excluded from the upstream passband. + +The frequency allocation for band US0 is defined in the regional annexes of this Recommendation. + +### 6.2.7 Required minimum bidirectional net data rate capability (MBDC) + +The bidirectional net data rate capability is the maximum value of the bidirectional net data rate that the VTU can support. The required MBDC is the minimum value of the bidirectional net data rate that a VTU compliant with a profile shall be capable of supporting. + +### 6.2.8 Aggregate interleaver and de-interleaver delay + +The required aggregate interleaver and de-interleaver delay is specified in terms of the sum of the end-to-end delays in the upstream and downstream directions over both latency paths, expressed in octets. Therefore, it involves both VTUs. Figure 6-1 illustrates an end-to-end connection with two latency paths and their interleavers and de-interleavers. + +![Figure 6-1: Illustration of all latency paths composing the aggregate interleaver and de-interleaver delay specified in each profile. The diagram shows two VTUs, VTU-O and VTU-R, connected by four horizontal lines representing latency paths. VTU-O contains four blocks: Interleaver DS,0; Interleaver DS,1; De-interleaver US,0; and De-interleaver US,1. VTU-R contains four blocks: De-interleaver DS,0; De-interleaver DS,1; Interleaver US,0; and Interleaver US,1. The paths are: Path 0 (downstream) from VTU-O Interleaver DS,0 to VTU-R De-interleaver DS,0; Path 1 (downstream) from VTU-O Interleaver DS,1 to VTU-R De-interleaver DS,1; Path 0 (upstream) from VTU-R Interleaver US,0 to VTU-O De-interleaver US,0; Path 1 (upstream) from VTU-R Interleaver US,1 to VTU-O De-interleaver US,1. Each path is labeled with 'Latency path p' and 'delay_octet_{x,p}'.](0fa5b60804100c3aead10404f9f226f9_img.jpg) + +G.993.2\_F06-1 + +Figure 6-1: Illustration of all latency paths composing the aggregate interleaver and de-interleaver delay specified in each profile. The diagram shows two VTUs, VTU-O and VTU-R, connected by four horizontal lines representing latency paths. VTU-O contains four blocks: Interleaver DS,0; Interleaver DS,1; De-interleaver US,0; and De-interleaver US,1. VTU-R contains four blocks: De-interleaver DS,0; De-interleaver DS,1; Interleaver US,0; and Interleaver US,1. The paths are: Path 0 (downstream) from VTU-O Interleaver DS,0 to VTU-R De-interleaver DS,0; Path 1 (downstream) from VTU-O Interleaver DS,1 to VTU-R De-interleaver DS,1; Path 0 (upstream) from VTU-R Interleaver US,0 to VTU-O De-interleaver US,0; Path 1 (upstream) from VTU-R Interleaver US,1 to VTU-O De-interleaver US,1. Each path is labeled with 'Latency path p' and 'delay\_octet\_{x,p}'. + +**Figure 6-1 – Illustration of all latency paths composing the aggregate interleaver and de-interleaver delay specified in each profile** + +The end-to-end delay in octets for the interleaver and de-interleaver pair on path $p$ , with $p = 0, 1$ , is given by: + +$$\text{delay\_octet}_{x,p} = (I_{x,p} - 1) \times (D_{x,p} - 1)$$ + +where the direction of transmission $x$ is either "DS" for downstream or "US" for upstream, $I_{x,p}$ is the interleaver block length, and $D_{x,p}$ is the interleaver depth. + +Each interleaver and each de-interleaver for each latency path requires at least $(\text{delay\_octet}_{x,p}/2)$ octets of memory to meet this delay. The actual amount of memory used is implementation specific. + +Referring to Figure 6-1, the aggregate interleaver and de-interleaver delay is specified as the sum $\text{delay\_octet}_{\text{DS},0} + \text{delay\_octet}_{\text{DS},1} + \text{delay\_octet}_{\text{US},0} + \text{delay\_octet}_{\text{US},1}$ , + +which can be rewritten as: + +$$\sum_p (I_{\text{US},p} - 1) \cdot (D_{\text{US},p} - 1) + (I_{\text{DS},p} - 1) \cdot (D_{\text{DS},p} - 1)$$ + +VTUs shall comply with the requirement: + +$$\sum_p (I_{\text{US},p} - 1) \cdot (D_{\text{US},p} - 1) + (I_{\text{DS},p} - 1) \cdot (D_{\text{DS},p} - 1) \leq \text{MAXDELAYOCTET}$$ + +where the summation is over all latency paths and MAXDELAYOCTET is the parameter "aggregate interleaver and de-interleaver delay", in octets, specified in Table 6-1 for the profile. + +The minimum amount of memory required in a transceiver (VTU-O or VTU-R) to meet this requirement is $\frac{\text{MAXDELAYOCTET}}{2}$ octets. The actual amount of memory used is implementation specific. + +### 6.2.9 Index of the highest supported downstream data-bearing subcarrier + +The index of the highest supported downstream data-bearing subcarrier is a band plan dependent parameter. It specifies the index of the highest-frequency subcarrier available for downstream transmission. A VTU-O compliant with a profile shall be capable of transmitting data-bearing subcarriers with indices up to (and including) the index specified in the profile under the heading "index of the highest supported downstream data-bearing subcarrier". The VTU shall not transmit data-bearing subcarriers with indices higher than this index. + +NOTE – The upper band edge frequency from which the index of the highest downstream data-bearing subcarrier has been derived appears in parentheses after the subcarrier index. The upper band edge frequency is informative. + +### 6.2.10 Index of the highest supported upstream data-bearing subcarrier + +The index of the highest supported upstream data-bearing subcarrier is a band plan dependent parameter. It specifies the index of the highest-frequency subcarrier available for upstream transmission. A VTU-R compliant with a profile shall be capable of transmitting data-bearing subcarriers with indices up to (and including) the index specified in the profile under the heading "index of the highest supported upstream data-bearing subcarrier". The VTU shall not transmit data-bearing subcarriers with indices higher than this index. + +NOTE – The upper band edge frequency from which the index of the highest upstream data-bearing subcarrier has been derived appears in parentheses after the subcarrier index. The upper band edge frequency is informative. + +### 6.2.11 Maximum interleaving depth + +The definition of the interleaving depth is in clause 9.4. To be compliant with a specific profile, a VTU shall be capable of providing interleaving depth up to and including the value of $D_{\max}$ specified in the row labelled "maximum interleaving depth ( $D_{\max}$ )" in Table 6-1. + +### 6.2.12 Parameter $(1/S)_{max}$ + +Parameter $(1/S)_{max}$ defines the maximum number of FEC codewords that the VTU is capable of transmitting during one DMT symbol (see detailed definition in clause 9.5.5). To be compliant with a specific profile, the VTU shall be capable of transmitting up to and including $(1/S)_{max}$ FEC codewords, of any valid size, per DMT symbol, as specified in the rows labelled "parameter $(1/S)_{max}$ downstream" and "parameter $(1/S)_{max}$ upstream" in Table 6-1. + +## 6.3 Profile compliance + +To be compliant with a selected profile, a VTU-O shall: + +- Be capable of transmitting subcarriers at the subcarrier spacing value specified in the profile; +- Be capable of transmitting data-bearing subcarriers with indices up to (and including) the index specified in the profile, for the applicable band plan, under the heading "index of the highest supported downstream data-bearing subcarrier"; +- Be capable of receiving US0 if the profile mandates support of US0; +- Support the aggregate interleaver and de-interleaver delay in octets specified in the profile; +- Support all values of $D$ up to and including $D_{max}$ , both upstream and downstream; +- Support all values of $1/S$ up to and including $(1/S)_{max}$ upstream and $(1/S)_{max}$ downstream; and +- Support its MBDC. + +To be compliant with a selected profile, a VTU-R shall: + +- Be capable of transmitting subcarriers at the subcarrier spacing value specified in the profile; +- Be capable of transmitting data-bearing subcarriers with indices up to (and including) the index specified in the profile, for the applicable band plan, under the heading "index of the highest supported upstream data-bearing subcarrier"; +- Be capable of transmitting US0 if the profile mandates support of US0; +- Support the aggregate interleaver and de-interleaver delay in octets specified in the profile; +- Support all values of $D$ up to and including $D_{max}$ , both upstream and downstream; +- Support all values of $1/S$ up to and including $(1/S)_{max}$ upstream and $(1/S)_{max}$ downstream; and +- Support its MBDC. + +Furthermore, a VTU complying with a selected profile shall: + +- Not use subcarrier spacing values not specified in the profile; +- Not transmit in a passband that includes subcarriers with indices higher than specified in the profile, for the applicable band plan and transmission direction, under the heading "index of the highest supported downstream (upstream) data-bearing subcarrier"; +- Not use an aggregate interleaver and de-interleaver delay greater than the value specified in the profile; and +- Not transmit at a power level greater than the maximum aggregate transmitter power specified in the profile. + +# 7 Transmission medium interface characteristics + +This clause specifies the interface between the transceiver and the transmission medium U-O2 and U-R2 reference points as defined in clause 5.4. For the purposes of this Recommendation, the U-O2/U-R2 and U-O/U-R interfaces are considered spectrally equivalent. + +## 7.1 Duplexing method and band plan construction + +VDSL2 transceivers shall use frequency division duplexing (FDD) to separate upstream and downstream transmissions. Overlapping of the upstream and downstream passbands is not allowed. The allocation of the upstream and downstream frequency bands is defined by the band plan, which is specified by band-separating frequencies. + +The VDSL2 signal can potentially utilize the frequency range up to 30 MHz, although the maximum frequency used by a VTU to transmit data depends on the selected band plan and the profile (see clause 6). + +### 7.1.1 Band plan below 12 MHz + +In the frequency range below 12 MHz, VDSL2 specifies the 5-band plan defined in Figure 7-1. The frequency band between $f_{0L}$ and $f_{0H}$ is denoted as US0. If used at all, this band shall be used only for upstream transmission. The four frequency bands denoted as DS1, US1, DS2, and US2, for the first downstream band, the first upstream band, the second downstream band, and the second upstream band, respectively, shall be defined by the band separating frequencies $f_1, f_2, f_3, f_4$ and $f_5$ , where $f_1 \geq f_{0H}$ . + +![Figure 7-1: Band plan in the frequency range up to 12 MHz. The diagram shows a horizontal axis representing frequency f [MHz]. The axis is divided into five segments by vertical lines at frequencies f_{0L}, f_{0H}, f_1, f_2, f_3, f_4, and f_5=12. The segments are labeled from left to right: US0 (between f_{0L} and f_{0H}), DS1 (between f_{0H} and f_1), US1 (between f_1 and f_2), DS2 (between f_2 and f_3), and US2 (between f_3 and f_4). The segments US0, US1, and US2 are shaded grey, while DS1 and DS2 are white. The axis ends with an arrow pointing right, labeled f [MHz]. A small text 'G.993.2_F07-1' is at the bottom right.](fd38170a3981416226ab91f7437ba821_img.jpg) + +Figure 7-1: Band plan in the frequency range up to 12 MHz. The diagram shows a horizontal axis representing frequency f [MHz]. The axis is divided into five segments by vertical lines at frequencies f\_{0L}, f\_{0H}, f\_1, f\_2, f\_3, f\_4, and f\_5=12. The segments are labeled from left to right: US0 (between f\_{0L} and f\_{0H}), DS1 (between f\_{0H} and f\_1), US1 (between f\_1 and f\_2), DS2 (between f\_2 and f\_3), and US2 (between f\_3 and f\_4). The segments US0, US1, and US2 are shaded grey, while DS1 and DS2 are white. The axis ends with an arrow pointing right, labeled f [MHz]. A small text 'G.993.2\_F07-1' is at the bottom right. + +Figure 7-1 – Band plan in the frequency range up to 12 MHz + +For the band plan below 12 MHz shown in Figure 7-1, the upstream passband shall be composed of the following portions of the frequency spectrum: $f_{0L} < f < f_{0H}$ , $f_2 < f < f_3$ , and $f_4 < f < f_5$ . The downstream passband shall be composed of the following portions of the frequency spectrum: $f_1 < f < f_2$ and $f_3 < f < f_4$ . The passband in each direction shall not contain frequencies above the frequency corresponding to the highest supported data-bearing subcarrier specified for that direction by the selected profile (6.1). + +The values of $f_{0L}$ , $f_{0H}$ , $f_1$ , $f_2$ , $f_3$ , and $f_4$ are specified in Annexes A, B and C. + +### 7.1.2 Band plan above 12 MHz + +In the frequency range between 12 MHz and 30 MHz, VDSL2 specifies at least one additional downstream or upstream band. Bands above 12 MHz are specified by additional band separating frequencies. The number of additional band separating frequencies depends on the number of bands defined between 12 MHz and 30 MHz. Any values of band separating frequencies defined between 12 MHz and 30 MHz are specified in Annexes A, B and C. + +When frequencies above 12 MHz are in use, the downstream (upstream) passband consists of the downstream (upstream) passband below 12 MHz plus any downstream (upstream) bands above 12 MHz. However, the passband in each direction shall not contain frequencies above the frequency corresponding to the highest supported data-bearing subcarrier specified for that direction by the selected profile (6.1). + +## 7.2 Power spectral density (PSD) + +### 7.2.1 Transmit PSD mask + +A VTU shall confine the PSD of its transmit signal to be within the transmit PSD mask. The transmit PSD mask is the lesser, at every frequency, of the Limit PSD mask specified in the relevant annex and, if applicable, a MIB PSD mask specified by the service provider, which is provided to the VTUs via the MIB. + +#### 7.2.1.1 MIB PSD mask construction + +This clause provides requirements and constraints for construction of the MIB PSD mask, which can be used to constrain the VDSL2 transmit PSD mask to levels lower than those specified by the Limit PSD masks. See Annexes A, B and C for specific Limit PSD masks defined for some geographic regions. + +In this clause, the term "band" corresponds to an upstream or downstream frequency band of the band plan defined in the relevant annex. The term "frequency range" is used to indicate a part of such a band. + +##### 7.2.1.1.1 Overview + +In some deployment scenarios, an operator may choose to force VTUs to transmit at levels lower than those specified by the Limit PSD masks. The MIB PSD mask is an additional tool that allows operators to shape the VTU-O and VTU-R transmit PSD masks. Power cut-back (see clause 12.3.3) and upstream power back-off (see clause 7.2.1.3) are tools that provide further reduction of the transmit PSD (below the transmit PSD mask). + +The MIB PSD mask shall lie at or below the Limit PSD mask specified in the selected annex. Its definition shall be under the network management control (a MIB-controlled mechanism), as defined in [ITU-T G.997.1]. + +The MIB PSD mask shall be specified in the CO-MIB by a set of breakpoints. Up to 16 breakpoints may be specified to construct the MIB PSD mask for all utilized upstream bands (including US0), and up to 32 breakpoints may be specified to construct the MIB PSD mask for all utilized downstream bands. It is not required to specify breakpoints for every band defined by a band plan. In frequency ranges in which the MIB PSD mask is not specified, the transmit PSD mask shall be equal to the Limit PSD mask. + +Each breakpoint used to specify the MIB PSD mask shall consist of a subcarrier index $t_n$ and a PSD mask value $PSD_n$ at that subcarrier expressed in dBm/Hz. The subcarrier indices shall always be calculated assuming 4.3125 kHz subcarrier spacing (i.e., independent of the subcarrier spacing actually used – see Table 6-1). + +Breakpoints for each utilized band shall be represented by the set $[(t_1, PSD_1), \dots, (t_n, PSD_n), \dots, (t_{NBP}, PSD_{NBP})]$ . The first breakpoint shall have the value $t_1 = \text{ceil}(f_x/4.3125 \text{ kHz})$ , where "ceil" denotes the ceiling function (rounding up to the nearest integer), and $f_x$ is the frequency of the lower band edge (see Figure 7-1). The index $t_1$ corresponds to the lowest-frequency subcarrier in the band, assuming that a profile with 4.3125 kHz subcarrier spacing is used. Except for the US0 band, the last breakpoint in the band shall have the value $t_{NBP} = \text{floor}(f_{x+1}/4.3125 \text{ kHz})$ , where "floor" denotes the floor function (rounding down to the nearest integer), and $f_{x+1}$ is the frequency of the upper band edge. For the US0 band, the last breakpoint is specified in clause 7.2.1.1.3. The index $t_{NBP}$ corresponds to the highest-frequency subcarrier in the band, assuming that a profile with 4.3125 kHz subcarrier spacing is used. Additional breakpoints within a band, if needed, shall be specified so that $t_n < t_{n+1}$ for $n = 2$ to $NBP - 1$ . The frequency $f_n$ corresponding to the index $t_n$ is $f_n = t_n \times 4.3125 \text{ kHz}$ . + +All $t_i$ in a particular frequency band shall be coded in the CO-MIB as unsigned integers. + +The value of the PSD at subcarrier $t_n$ , $PSD_n$ , shall be coded in the CO-MIB as an unsigned integer. The PSD values shall be coded from 0 dBm/Hz (coded as 0) to -127.5 dBm/Hz (coded as 255), in steps of 0.5 dBm/Hz. The valid range of PSD values is from 0 dBm/Hz to -95 dBm/Hz, although the values input via the MIB must be no higher than allowed by the Limit PSD mask. + +In the case that a profile specifying 8.625 kHz subcarrier spacing is used, the VTU shall subtract 1 from any odd values of $t_i$ for $i = 2$ to $NBP - 1$ . If $t_1$ is an odd number, the VTU shall add 1 to $t_1$ and use this value as the first breakpoint. If $t_{NBP}$ is an odd number, the VTU shall subtract 1 from $t_{NBP}$ and use this value as the last breakpoint. + +The MIB PSD mask parameter in the CO-MIB shall be a concatenation of the sets of breakpoints for all utilized bands. + +##### 7.2.1.1.2 Definition of breakpoints above US0 + +Breakpoints specified in the CO-MIB at frequencies above $f_i$ shall comply with the restrictions specified in this clause. + +###### 7.2.1.1.2.1 Definition of breakpoints for $\text{PSD}_n$ that are greater than or equal to $-80 \text{ dBm/Hz}$ + +For all breakpoints with values of $\text{PSD}_n$ in the MIB PSD mask that are greater than or equal to $-80 \text{ dBm/Hz}$ , the values of $\text{PSD}_n$ shall be defined with the following restrictions, except for the steep upward shape defined in clause 7.2.1.1.2.3, which can be used to provide steeper upward MIB PSD mask transitions. + +- For $t_n < t_{n+1}$ , the slope of the MIB PSD mask levels shall comply with: + +$$\left| \frac{\text{PSD}_{n+1} - \text{PSD}_n}{t_{n+1} - t_n} \right| \leq 0.75 \text{ dB/4.3125 kHz} \quad \text{for 4.3125 kHz subcarrier spacing}$$ + +$$\left| \frac{\text{PSD}_{n+1} - \text{PSD}_n}{t_{n+1} - t_n} \right| \leq 0.375 \text{ dB/4.3125 kHz} \quad \text{for 8.6250 kHz subcarrier spacing}$$ + +- $\min(\text{PSD}_n) \geq -80 \text{ dBm/Hz}$ , and $\max(\text{PSD}_n) - \min(\text{PSD}_n) \leq 40 \text{ dB}$ , where $\max(\text{PSD}_n)$ denotes the maximum and $\min(\text{PSD}_n)$ denotes the minimum of all breakpoint PSD values at or above $-80 \text{ dBm/Hz}$ . + +The MIB PSD mask at an arbitrary frequency $f$ shall be obtained by interpolation in dB on a linear frequency scale as follows: + +$$\text{MIB PSD mask}(f) = \text{PSD}_n + (\text{PSD}_{n+1} - \text{PSD}_n) \times \frac{(f / 4.3125 \text{ kHz}) - t_n}{t_{n+1} - t_n}, t_n < (f / 4.3125 \text{ kHz}) \leq t_{n+1}$$ + +Figure 7-2 illustrates the MIB PSD mask in the case that all breakpoints are above $-80 \text{ dBm/Hz}$ (with $\min(\text{PSD}_n) = \text{PSD}_5$ and $\max(\text{PSD}_n) = \text{PSD}_3$ ). + +![Figure 7-2: Illustration of a MIB PSD mask. The graph shows the Limit PSD mask as a dashed line and the MIB PSD mask as a solid line. The y-axis represents PSD levels (PSD1, PSD2, PSD3, PSD4, PSD5) and the x-axis represents frequency (t1(f_x), t2, t3, t4, t5(f_{x-1})). The MIB PSD mask is a piecewise linear function connecting the breakpoints (t1, PSD1), (t2, PSD2), (t3, PSD3), (t4, PSD4), and (t5, PSD5). The slope of the segments is indicated as being less than or equal to 0.75 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing and 0.375 dB/4.3125 kHz for 8.625 kHz sub-carrier spacing. The -80 dBm/Hz level is shown as a horizontal dashed line at the bottom.](83fdd6f5fafafa60502e4523c3244ad3_img.jpg) + +G.993.2\_F07-2 + +Figure 7-2: Illustration of a MIB PSD mask. The graph shows the Limit PSD mask as a dashed line and the MIB PSD mask as a solid line. The y-axis represents PSD levels (PSD1, PSD2, PSD3, PSD4, PSD5) and the x-axis represents frequency (t1(f\_x), t2, t3, t4, t5(f\_{x-1})). The MIB PSD mask is a piecewise linear function connecting the breakpoints (t1, PSD1), (t2, PSD2), (t3, PSD3), (t4, PSD4), and (t5, PSD5). The slope of the segments is indicated as being less than or equal to 0.75 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing and 0.375 dB/4.3125 kHz for 8.625 kHz sub-carrier spacing. The -80 dBm/Hz level is shown as a horizontal dashed line at the bottom. + +**Figure 7-2 – Illustration of a MIB PSD mask in the case all breakpoint $\text{PSD}_n$ values are greater than $-80 \text{ dBm/Hz}$** + +###### 7.2.1.1.2.2 Definition of breakpoints when some $PSD_n$ values are less than $-80$ dBm/Hz + +An operator may wish to specify a MIB PSD mask with some $PSD_n$ values that are below $-80$ dBm/Hz within a band (between $t_1$ and $t_{NBP}$ ) and with one frequency range from $t_{start}$ to $t_{stop}$ in which the MIB PSD mask is greater than $-80$ dBm/Hz. Such a case is illustrated in Figure 7-3. In this case, the MIB PSD mask breakpoint values $PSD_n$ in the ranges $t_1 \leq t < t_{start}$ and $t_{stop} < t \leq t_{NBP}$ shall be set no lower than the stopband PSD requirements defined in clause 7.2.2, where the low-edge and high-edge transition frequencies of the frequency range with the MIB PSD mask greater than $-80$ dBm/Hz are $f_{tr2} = t_{start} \times 4.3125$ kHz and $f_{tr1} = t_{stop} \times 4.3125$ kHz, respectively. + +![Figure 7-3: Illustration of the restrictions on breakpoints for a case in which the MIB PSD mask lies below -80 dBm/Hz between two band separating frequencies (t1 and tNBP) but above -80 dBm/Hz for some frequency range inside the band. The graph shows a 'Limit PSD mask' as a solid rectangle and a 'MIB PSD mask' as a dashed line. The MIB PSD mask is below -80 dBm/Hz between t1 and t_start, above -80 dBm/Hz between t_start and t_stop, and below -80 dBm/Hz between t_stop and tNBP. The transition frequencies are labeled as t_start = f_tr2 / 4.3125 kHz and t_stop = f_tr1 / 4.3125 kHz. The stopband PSD requirements are labeled as STOPBAND_PSD_ftr2 and STOPBAND_PSD_ftr1.](a52d0eb8feb4ddf21fec03f9f175e9d1_img.jpg) + +Figure 7-3: Illustration of the restrictions on breakpoints for a case in which the MIB PSD mask lies below -80 dBm/Hz between two band separating frequencies (t1 and tNBP) but above -80 dBm/Hz for some frequency range inside the band. The graph shows a 'Limit PSD mask' as a solid rectangle and a 'MIB PSD mask' as a dashed line. The MIB PSD mask is below -80 dBm/Hz between t1 and t\_start, above -80 dBm/Hz between t\_start and t\_stop, and below -80 dBm/Hz between t\_stop and tNBP. The transition frequencies are labeled as t\_start = f\_tr2 / 4.3125 kHz and t\_stop = f\_tr1 / 4.3125 kHz. The stopband PSD requirements are labeled as STOPBAND\_PSD\_ftr2 and STOPBAND\_PSD\_ftr1. + +**Figure 7-3 – Illustration of the restrictions on breakpoints for a case in which the MIB PSD mask lies below $-80$ dBm/Hz between two band separating frequencies ( $t_1$ and $t_{NBP}$ ) but above $-80$ dBm/Hz for some frequency range inside the band** + +Alternatively, an operator may wish to specify a MIB PSD mask which is below $-80$ dBm/Hz in a frequency range that lies between two frequency ranges in which the MIB PSD mask is greater than $-80$ dBm/Hz. For example, the MIB PSD mask is above $-80$ dBm/Hz in the range $t_{start1}$ to $t_{stop1}$ (range 1) and from $t_{start2}$ to $t_{stop2}$ (range 2), and from $t_{stop1}$ to $t_{start2}$ it is below $-80$ dBm/Hz, as illustrated in Figure 7-4. In this case, the MIB PSD mask breakpoint values $PSD_n$ for indices $t_{stop1} < t < t_{start2}$ shall be set not lower than the power sum of the high-edge stopband PSD of range 1 and the low-edge stopband PSD of range 2 (see clause 7.2.2), with the high-edge transition frequency of range 1 equal to $f_{tr1} = t_{stop1} \times 4.3125$ kHz and the low-edge transition frequency of range 2 equal to $f_{tr2} = t_{start2} \times 4.3125$ kHz, respectively. The power sum can be calculated using the following equation: + +$$\text{MIB PSD mask } (t_{stop1} < t < t_{start2}) \geq 10 \times \log_{10} (10^{0.1 \times \text{STOPBAND\_PSD\_ftr1}(t)} + 10^{0.1 \times \text{STOPBAND\_PSD\_ftr2}(t)})$$ + +NOTE – The power sum may result in PSD levels higher than $-80$ dBm/Hz. + +![Figure 7-4: Illustration of the restrictions on breakpoints for a frequency band in which the MIB PSD lies below -80 dBm/Hz between two frequency ranges where the PSD is above -80 dBm/Hz. The graph shows a 'Limit PSD mask' as a solid line and a 'MIB PSD mask' as a dashed line. The MIB PSD mask has a deep dip below -80 dBm/Hz between frequencies t_stop1 and t_stop2. The Limit PSD mask is a flat line above the MIB PSD mask. The graph is labeled with t_start1, t_stop1 = f_tr1 / 4.3125 kHz, t_stop2 = f_tr2 / 4.3125 kHz, t_stop2, and G.993.2_F07-4. The -80 dBm/Hz level is indicated by a horizontal dashed line.](32f80b2d70752613b6577797811f3a95_img.jpg) + +Figure 7-4: Illustration of the restrictions on breakpoints for a frequency band in which the MIB PSD lies below -80 dBm/Hz between two frequency ranges where the PSD is above -80 dBm/Hz. The graph shows a 'Limit PSD mask' as a solid line and a 'MIB PSD mask' as a dashed line. The MIB PSD mask has a deep dip below -80 dBm/Hz between frequencies t\_stop1 and t\_stop2. The Limit PSD mask is a flat line above the MIB PSD mask. The graph is labeled with t\_start1, t\_stop1 = f\_tr1 / 4.3125 kHz, t\_stop2 = f\_tr2 / 4.3125 kHz, t\_stop2, and G.993.2\_F07-4. The -80 dBm/Hz level is indicated by a horizontal dashed line. + +**Figure 7-4 – Illustration of the restrictions on breakpoints for a frequency band in which the MIB PSD lies below $-80\text{ dBm/Hz}$ between two frequency ranges where the PSD is above $-80\text{ dBm/Hz}$** + +###### 7.2.1.1.2.3 Definition of the steep upward shape + +It is possible to utilize a single steep upward shape to construct the MIB PSD mask. The selected steep upward shape can be used to achieve steeper slope in the MIB PSD mask definition than that specified in clause 7.2.1.1.2.1. Two valid steep upward shapes are specified. Only one of them may be used in the construction of the MIB PSD mask. + +###### 7.2.1.1.2.3.1 One-slope steep upward shape + +The one-slope steep upward shape is defined as: + +- $-80\text{ dBm/Hz} \leq \text{PSD}_i < -60\text{ dBm/Hz}$ ; +- $\text{PSD}_{i+1} \leq -60\text{ dBm/Hz}$ ; +- $\text{PSD}_j \leq \text{PSD}_{i+1}$ for all $j > (i+1)$ ; +- $\left| \frac{\text{PSD}_{i+1} - \text{PSD}_i}{t_{i+1} - t_i} \right| \leq 2.86\text{ dB} / 4.3125\text{ kHz}$ for 4.3125 kHz subcarrier spacing; +- $\left| \frac{\text{PSD}_{i+1} - \text{PSD}_i}{t_{i+1} - t_i} \right| \leq 1.43\text{ dB} / 4.3125\text{ kHz}$ for 8.6250 kHz subcarrier spacing. + +NOTE – These slopes correspond approximately to a maximum of 20 dB increase in the PSD mask level over seven subcarriers. + +The one-slope steep upward shape is illustrated in Figure 7-5. + +![Figure 7-5: Illustration of the one-slope steep upward shape. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus frequency on the x-axis. The y-axis has labels for PSD_{i+1} ≤ -60 and -80 ≤ PSD_i ≤ -60. The x-axis has labels for t_i and t_{i+1}. A shaded region represents the 'MTB PSD mask(f)'. A line segment with a positive slope connects a point at (t_i, PSD_i) to a point at (t_{i+1}, PSD_{i+1}). The slope is labeled as 'Slope ≤ 2.86 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing' and '1.43 dB/4.3125 kHz for 8.6250 kHz sub-carrier spacing'. The region to the right of t_{i+1} is labeled 'PSD_j ≤ PSD_{i+1}'. The bottom right corner of the graph is labeled 'G.993.2_F07-5'.](2154b1d6543a43735a7724180fff5586_img.jpg) + +Figure 7-5: Illustration of the one-slope steep upward shape. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus frequency on the x-axis. The y-axis has labels for PSD\_{i+1} ≤ -60 and -80 ≤ PSD\_i ≤ -60. The x-axis has labels for t\_i and t\_{i+1}. A shaded region represents the 'MTB PSD mask(f)'. A line segment with a positive slope connects a point at (t\_i, PSD\_i) to a point at (t\_{i+1}, PSD\_{i+1}). The slope is labeled as 'Slope ≤ 2.86 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing' and '1.43 dB/4.3125 kHz for 8.6250 kHz sub-carrier spacing'. The region to the right of t\_{i+1} is labeled 'PSD\_j ≤ PSD\_{i+1}'. The bottom right corner of the graph is labeled 'G.993.2\_F07-5'. + +Figure 7-5 – Illustration of the one-slope steep upward shape + +###### 7.2.1.1.2.3.2 Two-slope steep upward shape + +The two-slope steep upward shape is defined as: + +- $-80 \text{ dBm/Hz} \leq \text{PSD}_i < -60 \text{ dBm/Hz}$ ; +- $\text{PSD}_{i+2} \leq -36.5 \text{ dBm/Hz}$ ; +- $\text{PSD}_j \leq \text{PSD}_{i+2}$ for all $j > (i + 2)$ ; +- If $\text{PSD}_i > -80 \text{ dBm/Hz}$ then it is required that $\text{PSD}_k \geq \text{PSD}_i$ for all $k < i$ ; +- $\left| \frac{\text{PSD}_{i+1} - \text{PSD}_i}{t_{i+1} - t_i} \right| \leq 0.50 \text{ dB/4.3125 kHz}$ for 4.3125 kHz subcarrier spacing; +- $\left| \frac{\text{PSD}_{i+1} - \text{PSD}_i}{t_{i+1} - t_i} \right| \leq 0.25 \text{ dB/4.3125 kHz}$ for 8.6250 kHz subcarrier spacing; + +with $(t_{i+1} - t_i) \leq 47$ . + +- $\left| \frac{\text{PSD}_{i+2} - \text{PSD}_{i+1}}{t_{i+2} - t_{i+1}} \right| \leq 2.86 \text{ dB/4.3125 kHz}$ for 4.3125 kHz subcarrier spacing; +- $\left| \frac{\text{PSD}_{i+2} - \text{PSD}_{i+1}}{t_{i+2} - t_{i+1}} \right| \leq 1.43 \text{ dB/4.3125 kHz}$ for 8.6250 kHz subcarrier spacing; + +with $(t_{i+2} - t_{i+1}) \leq 7$ . + +NOTE – These slopes correspond approximately to a maximum of 23 dB increase in the PSD mask level over 47 subcarriers, and 20 dB over seven subcarriers. + +The two-slope steep upward shape is illustrated in Figure 7-6. + +![Figure 7-6: Illustration of the two-slope steep upward shape. The graph shows the Power Spectral Density (PSD) in dBm/Hz on the y-axis against frequency on the x-axis. The y-axis has labels for PSD_{i+2} ≤ -36.5, PSD_{i+1}, and -80 ≤ PSD_i ≤ -60. The x-axis has labels for t_i, t_{i+1}, and t_{i+2}, with intervals ≤ 47 and ≤ 7 between them. The MIB PSD mask (f) is shown as a line with two upward slopes. The first slope is between t_i and t_{i+1}, with a maximum slope of 0.50 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing or 0.25 dB/4.3125 kHz for 8.625 kHz sub-carrier spacing. The second slope is between t_{i+1} and t_{i+2}, with a maximum slope of 2.86 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing or 1.43 dB/4.3125 kHz for 8.625 kHz sub-carrier spacing. A note indicates that if PSD_i > -80, then PSD_k ≥ PSD_i for k < i. Another note states that for j > (i+2), PSD_j ≤ PSD_{i+2}. The graph is labeled G.993.2_F07-6.](4a243321537c0d3ea716335369163af1_img.jpg) + +Figure 7-6: Illustration of the two-slope steep upward shape. The graph shows the Power Spectral Density (PSD) in dBm/Hz on the y-axis against frequency on the x-axis. The y-axis has labels for PSD\_{i+2} ≤ -36.5, PSD\_{i+1}, and -80 ≤ PSD\_i ≤ -60. The x-axis has labels for t\_i, t\_{i+1}, and t\_{i+2}, with intervals ≤ 47 and ≤ 7 between them. The MIB PSD mask (f) is shown as a line with two upward slopes. The first slope is between t\_i and t\_{i+1}, with a maximum slope of 0.50 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing or 0.25 dB/4.3125 kHz for 8.625 kHz sub-carrier spacing. The second slope is between t\_{i+1} and t\_{i+2}, with a maximum slope of 2.86 dB/4.3125 kHz for 4.3125 kHz sub-carrier spacing or 1.43 dB/4.3125 kHz for 8.625 kHz sub-carrier spacing. A note indicates that if PSD\_i > -80, then PSD\_k ≥ PSD\_i for k < i. Another note states that for j > (i+2), PSD\_j ≤ PSD\_{i+2}. The graph is labeled G.993.2\_F07-6. + +Figure 7-6 – Illustration of the two-slope steep upward shape + +###### 7.2.1.1.2.4 Definition of breakpoints at the edge of a band + +No additional restrictions on the MIB PSD mask are imposed at the band edges. The values $PSD_1$ and $PSD_{NBP}$ can be any value between the value of the Limit PSD mask at that frequency and $-95$ dBm/Hz, provided that the MIB PSD mask construction rules are not violated as a result. + +##### 7.2.1.1.3 Definition of breakpoints in US0 + +If US0 shaping is supported, breakpoints $[(t_1, PSD_1), \dots, (t_n, PSD_n), \dots, (t_{NBPUS0}, PSD_{NBPUS0})]$ specified in the CO MIB at frequencies between $f_{0L}$ and $f_{0H}$ ( $f_{0L} \leq t_n \times 4.3125$ kHz $\leq f_{0H}$ ) shall comply with the restrictions specified in the following clauses. + +###### 7.2.1.1.3.1 Restriction on breakpoints in US0 + +The number of breakpoints in US0 ( $NBP_{US0}$ ) shall be between 2 and 6. The first breakpoint $t_1$ shall be equal to $\text{ceil}(f_{0L}/4.3125$ kHz). The last breakpoint, $t_{NBPUS0}$ , shall be smaller than or equal to $\text{floor}(f_{0H}/4.3125$ kHz). $t_{NBPUS0}$ shall be between 32 and 128. If $32 \leq t_{NBPUS0} \leq 64$ , $t_{NBPUS0}$ shall be a multiple of 4. If $64 < t_{NBPUS0} \leq 128$ , $t_{NBPUS0}$ shall be a multiple of 8. + +The breakpoint PSD values $PSD_n$ shall be specified according to the following constraints and requirements: + +- 1) The range between the minimum and maximum PSD values over all breakpoints shall be no greater than 24 dB, i.e., + +$$\max\{PSD_n\} - \min\{PSD_n\} \leq 24 \text{ dB},$$ + +where: + +$$\max\{PSD_n\} = \max(PSD_1, PSD_2, \dots, PSD_{NBPUS0}) \text{ and:}$$ + +$$\min\{PSD_n\} = \min(PSD_1, PSD_2, \dots, PSD_{NBPUS0})$$ + +2) The maximum slope between consecutive breakpoints shall be bound by at least one of the following two restrictions: + +i) $\forall n : 1 < n < NBP_{US0} :$ + +$$\left| \frac{PSD_n - PSD_{n-1}}{t_n - t_{n-1}} \right| \leq 0.75 \text{ dB/4.3125 kHz}$$ + +ii) $\forall n : 1 < n < NBP_{US0}$ and $(\max \{PSD_n\} - PSD_n \leq 6 \text{ dB}$ or $\max \{PSD_n\} - PSD_{n-1} \leq 6 \text{ dB}) :$ + +$$\left| \frac{PSD_n - PSD_{n-1}}{t_n - t_{n-1}} \right| \leq 0.6 \text{ dB/4.3125 kHz}$$ + +###### 7.2.1.1.3.2 Derivation of US0 PSD mask from defined breakpoints + +The MIB PSD mask at an arbitrary frequency $f$ between $t_1 \times 4.3125 \text{ kHz}$ and $t_{NBPUS0} \times 4.3125 \text{ kHz}$ shall be obtained by interpolation in dB on a linear frequency scale as follows: + +$$\text{MIB PSD mask } (f) = PSD_n + (PSD_{n+1} - PSD_n) \times \frac{(f/4.3125 \text{ kHz}) - t_n}{t_{n+1} - t_n}, \quad t_n < (f/4.3125 \text{ kHz}) \leq t_{n+1}$$ + +For frequencies below $t_1 \times 4.3125 \text{ kHz}$ , the MIB PSD mask shall be equal to $PSD_1$ . + +For $t_{NBPUS0} \times 4.3125 \text{ kHz} < f < 989 \text{ kHz}$ , the MIB\_PSD\_mask in dBm/Hz shall be the higher of: + +$$MIB\_PSD\_Mask(f) = PSD_{NBPUS0-1} - 72 \times \log_2((f/4.3125 \text{ kHz})/t_{NBPUS0-1})$$ + +and: + +$$MIB\_PSD\_Mask(f) = \max (-100 - 15 \times \log_{10}(f/686 \text{ kHz}) - 100)$$ + +#### 7.2.1.2 Egress control + +VDSL2 transmitters shall be able to reduce the PSD of the transmitted signal to a level below $-80 \text{ dBm/Hz}$ in 16 arbitrary frequency bands simultaneously. An example list of frequency bands (the amateur radio bands) is shown in Table 7-1. The value of $-80 \text{ dBm/Hz}$ shall be accounted for in the determination of MREFMASK (see Tables 7-3 through 7-5). + +**Table 7-1 – Amateur radio bands** + +| Band start
(kHz) | Band stop
(kHz) | +|---------------------|--------------------| +| 1 800 | 2 000 | +| 3 500 | 4 000 | +| 7 000 | 7 300 | +| 10 100 | 10 150 | +| 14 000 | 14 350 | +| 18 068 | 18 168 | +| 21 000 | 21 450 | +| 24 890 | 24 990 | +| 28 000 | 29 700 | + +The specific RFI bands to be notched are configured in the CO-MIB by the operator and set during the ITU-T G.994.1 handshake phase of initialization (see clause 12.3.2). + +The egress control parameters specified in [ITU-T G.997.1] are the start and stop frequencies of each frequency band in which the transmit PSD shall be reduced to a level below $-80$ dBm/Hz. The PSD slopes forming the notch are vendor discretionary. + +#### 7.2.1.3 Upstream power back-off (UPBO) + +Upstream power back-off (UPBO) shall be performed by the VTU-R to improve spectral compatibility between VDSL2 systems on loops of different lengths deployed in the same binder. This UPBO mechanism does not apply during the ITU-T G.994.1 handshake phase. In addition, UPBO for US0 is for further study. + +##### 7.2.1.3.1 Power back-off mechanism + +The VTU-R transmit PSD shall be reduced in a frequency-dependent manner using the procedure defined below: + +- The transmit PSD mask, PSDMASKus, for the VTU-R shall be calculated by the VTU-O to comply with settings from the network management system as defined in clause 7.2.1. PSDMASKus is communicated to the VTU-R at the beginning of initialization (in O-SIGNATURE); +- The VTU-R shall perform UPBO as described in clause 7.2.1.3.2 autonomously, i.e., without sending any significant information to the VTU-O until the UPBO is applied; +- After UPBO has been applied, the VTU-O shall be capable of adjusting the transmit PSD selected by the VTU-R; the adjusted transmit PSD shall be subject to the limitations given in clause 7.2.1.3.2. + +##### 7.2.1.3.2 Power back-off PSD mask + +The VTU-R shall explicitly estimate the electrical length of its loop, $kl_0$ , optionally $kl_0$ per band (i.e., $kl_0[band]$ ), and use this value to calculate the UPBO PSD mask, UPBOMASK, at the beginning of initialization. The VTU-R shall then adapt its transmit signal to conform strictly to the mask UPBOMASK( $kl_0, f$ ) during initialization and Showtime, while remaining below the PSDMASKus limit determined by the VTU-O as described in clause 7.2.1.3.1, and within the limit imposed by the upstream PSD ceiling (CDMAXMASKus, MAXMASKus). + +Two methods for upstream power back-off method are defined: + +- 1) The Reference PSD UPBO method; +- 2) The Equalized FEXT UPBO method (optional). + +The VTU-C and VTU-R shall support the reference PSD UPBO method, and may support the equalized FEXT UPBO method. If the equalized FEXT UPBO method is supported, it shall be supported for all upstream bands (except US0). This latter method is controlled via the parameter UPBO reference electrical length $kl_0\_REF$ , which is specified for each upstream band (see Table 12-25). + +###### 7.2.1.3.2.1 Electrical length estimation method + +Two methods are defined for deriving the electrical length autonomously: + +- 1) ELE-M0 the default method; +- 2) ELE-M1 the alternative method. + +Implementation of ELE-M0 is mandatory. Implementation of ELE-M1 is optional. + +The ELE-M1 shall be used if the CO-MIB parameter "Alternative Electrical Length Estimation Mode" (AELE-MODE) is set to a value of 1 or higher, and the mode is supported by the VTU-O and by the VTU-R. Otherwise, the ELE-M0 shall be used. + +The actual AELE-MODE used shall be reported in the CO-MIB parameter "Actual Alternative Electrical Length Estimation Mode" (ACT-AELE-MODE). If the VTU-O supports the optional ELE-M1 and the ELE-M0 is used, then the ACT-AELE-MODE parameter shall be set to a value of 0. + +###### 7.2.1.3.2.1.1 The default electrical length estimation method (ELE-M0) + +The default electrical length estimation method (ELE-M0) method is implementation dependent. + +NOTE – A possible estimate of $kl_0$ is as follows: + +$$kl_0 = \text{MIN}\left(\frac{\text{loss}(f)}{\sqrt{f}}\right) \text{ dB}$$ + +where the minimum is taken over the usable VDSL2 frequency band above 1 MHz. The function $\text{loss}(f)$ is the insertion loss in dB of the loop at frequency $f$ . This definition is abstract, implying an infinitely fine grid of frequencies. + +###### 7.2.1.3.2.1.2 The alternative electrical length estimation method (ELE-M1) + +The alternative electrical length estimation method (ELE-M1) method is applied in the VTU-R to separately estimate the electrical length, in each downstream band, and in the VTU-O to separately estimate the electrical length, in each upstream band, excluding US0: + +$$\text{ELE}[\text{band}] = \text{PERCENTILE}\left(\left\{\frac{\text{loss}(f, \text{rx\_thresh}(\text{band}))}{\sqrt{f}} \mid f \in \text{band}\right\}, \text{UPBOELMT}\right) [\text{dB}]$$ + +Where: + +1. $\text{band} \in \{\text{aele\_bands}\}$ , where $\{\text{aele\_bands}\}$ is the set of all supported upstream and downstream bands except US0, and $f > 1.8 \times f_1$ for DS1. + +NOTE 1 – $1.8 \times f_1$ is used as the lower limit in calculations on the basis that for most cables above this frequency the $\sqrt{f}$ approximation is sufficiently accurate for the purposes of UPBO, and is sufficiently above the US0-DS1 boundary to limit the impact of DS1 high pass filtering. Compared to the use of 1 MHz, this frequency makes it less likely that in-premises bridge taps will have a large effect on the electrical length estimate ELE[DS1]. + +2. $\text{loss}(f, \text{rx\_threshold}(\text{band}))$ is the estimated transmission path loss in dB at tone frequency $f$ in MHz, which is set to the special value 307.1 dB if the minimum received signal plus noise power during loss estimation is less than $\text{rx\_threshold}(\text{dBm/Hz})$ for the particular $\text{band}$ . + +The maximum values for $\text{rx\_threshold}(\text{band})$ are: –130 dBm/Hz in the downstream bands, and –115 dBm/Hz in the upstream bands. However, the VTU may use lower threshold $\text{rx\_threshold}(\text{band})$ settings. The actual threshold used shall be reported in CO-MIB parameters RXTHRSUDS and RXTHRSUS. + +3. The $\text{PERCENTILE}(\{x\}, y)$ function returns the maximum value $w$ in set $\{x\}$ such that the number of elements in $\{x\}$ with value less than $w$ is less than $y$ percent of the total number of elements in $\{x\}$ . + +4. UPBO Electrical Length Minimum Threshold (UPBOELMT) is a CO-MIB parameter which determines the percentile to be used in finding the qualified minimum of a set of frequency dependent electrical length estimates in a particular VDSL2 band. + +NOTE 2 – The $\text{PERCENTILE}$ function is used to mitigate the effect of RFI ingress. It provides an estimate of the minimum of a set of per-tone electrical length estimates, ignoring a small proportion of tones affected by high level narrow band RFI ingress. + +If ELE-M1 is applied, the same value for $kl_0$ (*ELEDS*) is applied in all upstream bands except US0, at the beginning of initialisation. This is derived from *ELE[band]* values estimated in the VTU-R for all downstream bands: + +$$\begin{aligned} ELEDS &= MIN(ELE[band]), \text{ where } band \in \{ds\_bands\} \\ \text{and} \\ kl_0[us\_band] &= ELEDS \text{ for all } us\_band \in \{upbo\_bands\} \end{aligned}$$ + +where $\{ds\_bands\}$ is the set of all supported downstream bands with $f > 1.8 \times f_1$ for DS1, and $us\_band \in \{upbo\_bands\}$ the set of all supported upstream bands except US0. + +The intermediate value ELEDS is sent to the VTU-O as "Estimate of electrical length" in R-MSG-1, as defined in clause 12.3.3.2.2.1. + +An intermediate value ELEUS is determined in the VTU-O as follows: + +$$ELEUS = MIN(ELE[band]), \text{ where } band \in \{upbo\_bands\}.$$ + +The final electrical length is determined during initialisation and sent from the VTU-O to the VTU-R during initialisation in the O-UPDATE message (see clause 12.3.3.2.1.2). Separate values are provided for each upstream band, excluding US0. The values are selected according to the CO-MIB parameter AELE-MODE: + +$$\begin{aligned} &\text{For all upstream bands except US0, } band \in \{upbo\_bands\} \\ &\text{AELE-MODE} = 0 \quad kl_0[band] = \text{ELE-M0 VTU-O } kl_0 \text{ estimate} \\ &\text{AELE-MODE} = 1 \quad kl_0[band] = ELEDS [dB], \text{ band} \in \{upbo\_bands\} \\ &\text{AELE-MODE} = 2 \quad kl_0[band] = ELE[band] [dB], \text{ band} \in \{upbo\_bands\} \\ &\text{AELE-MODE} = 3 \quad kl_0[band] = MIN(ELEUS, ELEDS) [dB], \text{ band} \in \{upbo\_bands\} \end{aligned}$$ + +If the CO-MIB parameter *UPBOKL* (*Force CO-MIB electrical length*) is set to 1 then the final electrical length is set defined by the CO-MIB parameter *UPBOKL* (*Upstream electrical length*), and applied as follows: + +$$kl_0[band] = UPBOKL, \text{ band} \in \{upbo\_bands\}$$ + +If ELE-M1 is supported the following parameters shall be reported by the transceivers, whether or not *UPBOKL* is set: + +*ELE[band]*, $band \in \{ds\_bands\}$ shall be reported by the VTU-R to the VTU-O in the R-MSG 1 message (see clause 12.3.3.2.2.1) + +*ELE[band]*, $band \in \{aele\_bands\}$ shall be reported by the VTU-O via the CO-MIB, where $\{aele\_bands\} = \{ds\_bands\} \cup \{upbo\_bands\}$ . + +###### 7.2.1.3.2.2 UPBO mask + +If the optional equalized FEXT UPBO method is not supported, or if the optional equalized FEXT UPBO method is supported but $kl_{0\_REF} = 0$ for a given upstream band, the UPBOMASK for that given band is calculated as: + +$$UPBOMASK(kl_0, f) = UPBOPSD(f) + LOSS(kl_0, f) + 3.5 \text{ [dBm/Hz]},$$ + +where: + +$$\begin{aligned} LOSS(kl_0, f) &= kl_0 \sqrt{f} \text{ [dB]}, \text{ and} \\ UPBOPSD(f) &= -a - b \sqrt{f} \text{ [dB/Hz]}, \end{aligned}$$ + +with $f$ expressed in MHz. + +In case ELE-M0 is used, $kl_0$ is defined as a single value. + +In case ELE-M1 is used, $kl_0$ is defined separately for each band in $\{upbo\_bands\}$ , i.e., $kl_0[band]$ . + +UPBOPSD( $f$ ) is a function of frequency but is independent of length and type of loop. + +If the optional equalized FEXT UPBO method is supported, and $kl_{0\_REF} \neq 0$ for a given upstream band, the UPBOMASK for that given band is calculated as: + +- for ( $1.8 \leq kl_0 < kl_{0\_REF}$ ): + +$$UPBOMASK(f) = -a - b\sqrt{f} + 10 \log_{10}\left(\frac{kl_{0\_REF}}{kl_0}\right) + LOSS(kl_0, f) + 3.5 \quad [\text{dBm/Hz}]$$ + +- for ( $kl_0 < 1.8$ ): + +$$UPBOMASK(f) = -a - b\sqrt{f} + 10 \log_{10}\left(\frac{kl_{0\_REF}}{1.8}\right) + LOSS(1.8, f) + 3.5 \quad [\text{dBm/Hz}]$$ + +- for ( $kl_0 \geq kl_{0\_REF}$ ): + +$$UPBOMASK(f) = -a - b\sqrt{f} + LOSS(kl_0, f) + 3.5 \quad [\text{dBm/Hz}]$$ + +where: + +$$LOSS(kl_0, f) = kl_0\sqrt{f} \quad [\text{dB}]$$ + +with $f$ expressed in MHz. + +For both methods of UPBO, the values of $a$ and $b$ , which may differ for each upstream band, are obtained from the CO-MIB as specified in [ITU-T G.997.1] and shall be provided to the VTU-R during initialization (see clause 12.3.3.2.1.1). Specific values may depend on the geographic region (see Annexes A, B and C). + +For the optional equalized FEXT UPBO method, the value $kl_{0\_REF}$ is obtained from the CO-MIB as specified in [ITU-T G.997.1] and shall be provided to the VTU-R during initialization (see clause 12.3.3.2.1.1). + +If the estimated value of $kl_0$ is smaller than 1.8, the VTU shall be allowed to perform power back-off as if $kl_0$ were equal to 1.8. The estimate of the electrical length should be sufficiently accurate to avoid spectrum management problems and additional performance loss. + +NOTE 1 – To meet network specific requirements, network management may provide a means to override the VTU-R's autonomous estimate of $kl_0$ (see clause 12.3.3.2.1.2, O-UPDATE). + +NOTE 2 – The nature of coupling between loops in a cable binder results in a rapidly decreasing FEXT as the loop length decreases. As the electrical length $kl_0$ of the loop decreases below 1.8, no further increase in power back-off is needed. An electrical length of 1.8 corresponds to, for example, a 0.4 mm loop about 70 m long. + +### 7.2.2 Stopband PSD + +The PSD of the signal transmitted in the stopbands shall comply with a Limit PSD Mask and a wide-band power limit as defined in Figure 7-7. The Limit PSD Mask applies between band separating frequencies $f_{tr1}$ and $f_{tr2}$ . The wide-band power limit $P_{max}$ applies in that part of the band lying between the transition bands (width $\Delta f_T$ ). + +The width of the transition bands $\Delta f_T$ shall be independent of frequency and shall not exceed 175 kHz. Transition bands and values of the stopband PSD in the frequency range $f_{tr} < 686$ kHz are specified in regional annexes. + +![Figure 7-7: Limit PSD mask and wide-band power limit in the stopbands. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus frequency (f) on the x-axis. The mask consists of a passband, two transition bands of width Δf_T, and a stopband. The PSD is -80 dBm/Hz at the transition frequencies f_{ir1} and f_{ir2}. In the stopband, the PSD is constant at PSD_{max} dBm/Hz. A horizontal line represents the maximum power limit P_{max} dBm in a 1-MHz window. The graph is labeled G.993.2_F07-7.](657acccf744d33f1fc3a1652741a256e_img.jpg) + +Figure 7-7: Limit PSD mask and wide-band power limit in the stopbands. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus frequency (f) on the x-axis. The mask consists of a passband, two transition bands of width Δf\_T, and a stopband. The PSD is -80 dBm/Hz at the transition frequencies f\_{ir1} and f\_{ir2}. In the stopband, the PSD is constant at PSD\_{max} dBm/Hz. A horizontal line represents the maximum power limit P\_{max} dBm in a 1-MHz window. The graph is labeled G.993.2\_F07-7. + +**Figure 7-7 – Limit PSD mask and wide-band power limit in the stopbands** + +The Limit PSD mask values and the power limit values inside the stopbands shall be as listed in Table 7-2 and shown in Figure 7-7. The values between the points listed in Table 7-2 shall be found using linear interpolation over a linear scale of frequency. The signal transmitted in the stopbands shall comply with both the Limit PSD mask (verified using a 10 kHz measurement bandwidth) and the power limit in a 1-MHz sliding window presented in Table 7-2. + +**Table 7-2 – Stopband PSD requirements** + +| Frequency (MHz) | Limit PSD mask value (PSD max dBm/Hz) | Maximum power in a 1 MHz sliding window (P max dBm) | +|----------------------------------------------------------|-----------------------------------------------------------|----------------------------------------------------------------| +| < 0.686 | Subject to regional annexes | | +| 0.686-4.0 | -100 | | +| 4.0-5.0 | -100 | -50 | +| 5.0-30.0 | -100 | -52 | +| ≥ 30.0 | -110 | | +| Frequency (MHz) | Limit PSD mask value at the transition frequency (dBm/Hz) | | +| Transition frequency ( $f = f_{ir1}$ and $f = f_{ir2}$ ) | -80 | | + +The power measured in any 1 MHz window [ $f$ , $f+1$ MHz] with $f \geq f_{ir1} + \Delta f_T$ and $f+1$ MHz $\leq f_{ir2} - \Delta f_T$ shall comply with the value shown in Table 7-2 (with $f_{ir1}$ , $f_{ir2}$ and $\Delta f_T$ as shown in Figure 7-7). If the value ( $f_{ir2} - f_{ir1} - 2\Delta f_T$ ), is less than 1 MHz, the bandwidth of the measurement device should be reduced and set to $\Delta f_M$ , so that $\Delta f_M \leq f_{ir2} - f_{ir1} - 2\Delta f_T$ . The measured result shall be recalculated to the 1 MHz sliding window as: + +$$P_{max} = P - 10 \times \log_{10} (\Delta f_M)$$ + +where: + +$P$ is the measured result in dBm + +$\Delta f_M$ is the bandwidth used for the measurement in MHz + +### 7.2.3 PSD and PSD mask summary + +A summary of the various PSDs and PSD masks used during initialization and showtime is presented in Table 7-3. + +**Table 7-3 – PSD masks and PSDs used in this Recommendation** + +| Parameter | Description | Notation | +|---------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------| +| Limit PSD mask | A PSD mask specified in an annex of this Recommendation (Annex A, B, or C). | LIMITMASKds,
LIMITMASKus | +| MIB PSD mask | A PSD mask specified by the operator for passbands only and intended to restrict the transmit PSD to levels below those allowed by the applicable Limit PSD mask. | MIBMASKds,
MIBMASKus | +| Transmit PSD mask | A PSD mask that is the minimum of 1) the applicable Limit PSD mask, 2) the MIB PSD mask, and 3) vendor-discretionary mask restrictions imposed by the VTU-O. | PSDMASKds,
PSDMASKus | +| UPBO PSD mask | A PSD mask, for the upstream direction only, which is calculated by the VTU-R as a function of the electrical length of the loop (see clause 7.2.1.3.2). | UPBOMASK | +| Channel discovery PSD | The PSD of signals transmitted by a VTU during the channel discovery phase of initialization. | CDPSDds,
CDPSDus | +| PSD ceiling | A PSD level, independent of frequency (and indicated by a single value), that limits the transmit PSD mask to form the MEDLEY reference PSD mask. (see clauses 12.3.3.2.1.1, 12.3.3.2.1.2, 12.3.3.2.2.1, and 12.3.3.2.2.2). | CDMAXMASKds,
CDMAXMASKus,
MAXMASKds,
MAXMASKus | +| MEDLEY reference PSD mask | The transmit PSD mask limited at every frequency by the PSD ceiling and to $-80$ dBm/Hz inside the RFI bands. In the upstream direction, also limited in accordance with the UPBO requirements. | MREFMASKds,
MREFMASKus | +| MEDLEY reference PSD | The PSD of signals transmitted by a VTU during the training phase and the channel analysis and exchange phase of initialization. | MREFPSDds,
MREFPSDus | +| Showtime PSD | The PSD of signals transmitted by a VTU during showtime. | PSDds
PSDus | + +The details of computation rules for the PSD masks and setting rules for the PSDs are presented in Table 7-4. + +**Table 7-4 – Summary of PSD and PSD mask calculations** + +| Parameter | Calculation | +|-----------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmit PSD mask (PSDMASK) | Calculated by the VTU-O as (Note):
$PSDMASKds(f) = \min(LIMITMASKds(f), MIBMASKds(f), ds\_mask\_restrictions\_by\_VTU-O)$
$PSDMASKus(f) = \min(LIMITMASKus(f), MIBMASKus(f), us\_mask\_restrictions\_by\_VTU-O)$ | +| Channel discovery PSD (CDPSD) | CDPSDds, expressed in dBm/Hz, is determined by the VTU-O, and for subcarriers from the SUPPORTEDCARRIERsd set:
$CDPSDds(f) \leq \begin{cases} \min[(PSDMASKds(f) - 3.5), (CDMAXMASKds - 3.5)], f \notin RFIBANDS \\ \min[(PSDMASKds(f) - 3.5), (CDMAXMASKds - 3.5) - 83.5], f \in RFIBANDS \end{cases}$ For all other subcarriers, $CDPSDds(f) \leq PSDMASKds(f)$ .
For any valid setting of CDPSDds, the aggregate downstream transmit power shall not exceed the MAXNOMATPds.
CDPSDus, expressed in dBm/Hz, is determined by the VTU-R, and for subcarriers from the SUPPORTEDCARRIERsus set:
$CDPSDus(f) \leq \begin{cases} \min[(PSDMASKus(f) - 3.5), (CDMAXMASKus - 3.5), (UPBOMASK(klo, f) - 3.5)], f \notin RFIBANDS \\ \min[(PSDMASKus(f) - 3.5), (CDMAXMASKus - 3.5), (UPBOMASK(klo, f) - 3.5), -83.5], f \in RFIBANDS \end{cases}$ For all other subcarriers, $CDPSDus(f) \leq PSDMASKus(f)$ .
For any valid setting of CDPSDus, the aggregate upstream transmit power shall not exceed the control parameter MAXNOMATPus defined in clause 10.3.4.2.1. | +| MEDLEY reference PSD mask (MREFMASK) | $MREFMASKds(f) = \begin{cases} \min(PSDMASKds(f), MAXMASKds), f \notin RFIBANDS \\ \min(PSDMASKds(f), MAXMASKds, -80), f \in RFIBANDS \end{cases}$ $MREFMASKus(f) = \begin{cases} \min(PSDMASKus(f), MAXMASKus, UPBOMASK(klo, f)), f \notin RFIBANDS \\ \min(PSDMASKus(f), MAXMASKus, UPBOMASK(klo, f) - 80), f \in RFIBANDS \end{cases}$ | +| MEDLEY reference PSD (MREFPSD) | $MREFPSDds(f) \leq (MREFMASKds(f) - 3.5 \text{ dB})$ for all subcarriers of the downstream passband (including downstream RFI bands allowed to carry data) and $MREFPSDds(f) \leq MREFMASKds(f)$ for all other frequencies.
For any valid setting of MREFPSDds, the aggregate downstream transmit power shall not exceed the MAXNOMATPds.
$MREFPSDus(f) \leq (MREFMASKus(f) - 3.5 \text{ dB})$ for all subcarriers of the upstream passband (including upstream RFI bands allowed to carry data) and $MREFPSDus(f) \leq MREFMASKus(f)$ for all other frequencies.
For any valid setting of MREFPSDus, the aggregate upstream transmit power shall not exceed the control parameter MAXNOMATPus defined in clause 10.3.4.2.1. | +| NOTE – RFI bands are not incorporated in the transmit PSD mask. | | + +NOTE – Table 7-4 specifies PSDs and PSD masks at every frequency (i.e., in both the passband and the stopbands). To avoid communication of redundant information, the corresponding messages during initialization do not describe the PSDs in the full frequency range, nor do they describe the RFI bands. + +The process of determining the PSDs and PSD masks of the VTU during initialization and showtime is summarized in Table 7-5. + +**Table 7-5 – Summary: Determination and use of PSDs and PSD masks** + +| Parameter | When determined | When communicated between VTUs (Note) | When used | +|---------------------------------|-------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------| +| Limit PSD mask (LIMITMASK) | Configuration of MIB before start of initialization | Not communicated | By VTU-O, before start of initialization, to calculate downstream and upstream transmit PSD masks | +| MIB PSD mask (MIBMASK) | Configuration of MIB before start of initialization | Not communicated | By VTU-O, before start of initialization, to calculate downstream and upstream transmit PSD masks | +| RFI bands (RFIBANDS) | Configuration of MIB before start of initialization | RFIBANDS is sent by VTU-O to VTU-R during ITU-T G.994.1 handshake phase | Notches are applied in designated bands in applicable transmission direction(s) from the start of initialization and thereafter | +| Initial PSD ceiling (CDMAXMASK) | By the VTU-O before start of initialization, by the VTU-R at the beginning of channel discovery phase | Initial value of downstream PSD ceiling is sent by VTU-O to VTU-R in O-SIGNATURE; initial value of upstream PSD ceiling is sent by VTU-R to VTU-O in R-MSG1 | For all signals during the channel discovery phase (initial downstream ceiling avoids saturation of the VTU-R over short loops) | +| Transmit PSD mask (PSDMASK) | By the VTU-O before start of initialization | PSDMASKds and PSDMASKus are sent by VTU-O to VTU-R in O-SIGNATURE | For all signals during channel discovery phase | +| UPBO PSD mask (UPBOMASK) | By the VTU-R at the beginning of the channel discovery phase | Not communicated | For all signals during channel discovery phase and thereafter | +| Channel discovery PSD (CDPSD) | At the beginning of channel discovery phase; VTU-O determines CDPSDds, VTU-R determines CDPSDus | CDPSDds is sent by VTU-O to VTU-R in O-SIGNATURE; CDPSDus is sent by VTU-R to VTU-O in R-MSG 1 | For all signals during channel discovery phase | +| PSD ceiling (MAXMASK) | At the end of channel discovery phase; VTU-R determines MAXMASKds, VTU-O determines MAXMASKus | MAXMASKus is sent by VTU-O to VTU-R in O-UPDATE. MAXMASKds is sent by VTU-R to VTU-O in R-UPDATE | From the beginning of training phase and thereafter | + +**Table 7-5 – Summary: Determination and use of PSDs and PSD masks** + +| Parameter | When determined | When communicated between VTUs (Note) | When used | +|--------------------------------------|-------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------| +| MEDLEY reference PSD mask (MREFMASK) | At the end of channel discovery phase; VTU-O determines MREFMASKds, VTU-R determines MREFMASKus | Not communicated | From the beginning of training phase and thereafter during initialization and showtime | +| MEDLEY reference PSD (MREFPSD) | At the end of channel discovery phase; VTU-O determines MREFPSDds, VTU-R determines MREFPSDus | MREFPSDds is sent by VTU-O to VTU-R in O-PRM; MREFPSDus is sent by VTU-R to VTU-O in R-PRM | During the training and channel analysis and exchange phases | +| Showtime PSD | At the end of the channel analysis and exchange phase | Determined by the MREFPSD and the gain values ( $g_i$ ) communicated during the channel analysis and exchange phase (O-PMD and R-PMD messages). Shall not exceed MREFMASK. | During showtime | + +NOTE – Only the minimum set of relevant parameters characterizing PSDs and PSD masks is communicated during initialization. The communication protocols and formats are described in clause 12. + +## 7.3 Termination impedance + +A termination impedance of $R_V = 100$ Ohm, purely resistive, at the U interface, shall be used over the entire VDSL2 frequency band for both VTUs. In particular, $R_V = 100$ Ohm shall be used as a termination for the transmit PSD and power definition and verification. + +NOTE – This termination impedance approximates the insertion-point impedance of the VDSL2 test loop and harmonizes VDSL2 and ADSL2. + +## 7.4 Longitudinal conversion loss + +Longitudinal conversion loss (LCL) is a measure of the degree of unwanted transversal signal produced at the input of the VDSL2 transceiver due to the presence of a longitudinal signal on the connecting leads. The longitudinal voltage ( $V_{cm}$ ) to transversal voltage ( $V_{diff}$ ) ratio shall be measured in accordance with [ITU-T G.117] and [ITU-T O.9]. During the measurement, the transceiver under test shall be powered, and in the L3 state (see clause 12.1). + +$$LCL = 20 \log_{10} \left| \frac{V_{cm}}{V_{diff}} \right| \text{dB}$$ + +The LCL of the VDSL2 transceiver shall be greater than or equal to 38 dB in the frequency band up to 12 MHz. + +In the frequency band above 12 MHz, the LCL of the VDSL2 transceiver for frequency $f$ shall be greater than or equal to $38 \text{ dB} - 20 \log_{10}(f_{\text{MHz}}/12)$ for $12 \text{ MHz} < f < F_{max}$ , where $F_{max}$ is the higher of the highest passband frequency in the upstream and downstream directions for the Limit PSD masks selected. + +The termination impedance of the transceiver for LCL measurement shall be $R_V = 100$ Ohm. The LCL shall be measured at the U-O2 (U-R2) interface. LCL shall be measured in the frequency band between the lower of the lowest passband frequency in the upstream and downstream directions and $F_{max}$ . + +NOTE 1 – The equipment balance should be better than the anticipated access network balance in order to minimize the unwanted emissions and susceptibility to external RFI. + +NOTE 2 – VDSL2 performance may benefit from even higher balance. Where subject to repetitive electrical impulse noise, systems operating at frequencies where the cable balance may be 50 dB could be limited in capacity by a 38 dB balance. + +NOTE 3 – The required LCL may be increased in a future revision of this Recommendation. + +# **8 Transport protocol specific transmission convergence (TPS-TC) function** + +The transport protocol specific transmission convergence (TPS-TC) sublayer resides between the $\gamma$ reference point and the $\alpha/\beta$ reference point as presented in the VDSL2 and VTU functional model in Figure 5-1. This functional model defines the TPS-TC sublayer as containing one or more TPS-TCs providing transport of user data utilizing different transport protocols, a management TPS-TC (MPS-TC) providing eoc transport over the VDSL2 link, an NTR-TC providing transport of the network timing reference, and a ToD-TC providing transport of the time-of-day. + +Functionality, parameters, and application interface ( $\gamma$ interface) characteristics of the user data TPS-TC are specified in clause 8.1. Functionality, parameters, and application interface ( $\gamma$ interface) characteristics of the MPS-TC are specified in clause 8.2. Functionality, parameters, and application interface ( $\gamma$ interface) characteristics of the NTR-TC are specified in clause 8.3. Functionality, parameters, and application interface ( $\gamma$ interface) characteristics of the ToD-TC are specified in clause 8.4. + +The mandatory TPS-TC sublayer configuration shall include the MPS-TC, the NTR-TC, and at least one user data TPS-TC. Support of a second user data TPS-TC or the ToD-TC is optional. Each TPS-TC operates over a separate bearer channel, where the PMS-TC may allocate these bearer channels to a single or to separate latency paths. + +## **8.1 The user data TPS-TC** + +### **8.1.1 User data TPS-TC types** + +There are three types of user data TPS-TCs defined in this Recommendation: + +- 1) Type 1: Synchronous transfer mode (STM) transmission convergence (STM-TC); +- 2) Type 2: Asynchronous transfer mode (ATM) transmission convergence (ATM-TC); and +- 3) Type 3: Ethernet and generic packet transport packet transfer mode transmission convergence (PTM-TC). + +Each of these three types is defined as an application option. The VTU-O selects the user data TPS-TC type for each bearer channel, both upstream and downstream, based on the type of higher layer data it chooses to support on that bearer channel. The enabled user data TPS-TC type for each of the bearer channels is indicated during initialization. + +Functionality, parameters, and application interface ( $\gamma$ interface) characteristics of the user data TPS-TCs supporting STM transport (STM-TC), ATM transport (ATM-TC), and Ethernet and generic packet transport (PTM-TC) are specified in L.1, L.2 and L.3, respectively. + +The transmit signals of the TPS-TC are submitted to the $\alpha/\beta$ interface. Signals passing via the $\alpha/\beta$ interface in both directions have an application-independent (transport protocol independent) format, as specified in clause 8.1.2. The particular bit rates for each of the multiplexed TPS-TCs at the $\alpha/\beta$ reference point are determined during system configuration. + +### 8.1.2 $\alpha/\beta$ interface specification + +The $\alpha$ and $\beta$ reference points define corresponding interfaces between the TPS-TC and PMS-TC at the VTU-O and VTU-R sides, respectively. Both interfaces are logical, application independent, and identical. The interfaces comprise the following flows of hypothetical signals between the TPS-TC and the PMS-TC sublayers: + +- Data flow; +- Synchronization flow; and +- Control flow. + +The various signals are summarized in Table 8-1. + +**Table 8-1 – User data TPS-TC: $\alpha/\beta$ interface data and synchronization flows signal summary** + +| Signal | Description | Direction | +|--------------------------------|-----------------------|-----------------------------| +| Data signals | | | +| Tx | Transmit data | TPS-TC $\rightarrow$ PMS-TC | +| Rx | Receive data | TPS-TC $\leftarrow$ PMS-TC | +| Synchronization signals | | | +| Osync_t | Transmit octet timing | TPS-TC $\leftarrow$ PMS-TC | +| Osync_r | Receive octet timing | | +| Control signals | | | +| Syncflag | Reconfiguration flag | TPS-TC $\leftarrow$ PMS-TC | + +#### 8.1.2.1 Data flow + +The data flow comprises two generic octet-oriented streams with the rates defined by the physical net data rate capabilities: + +- Transmit data stream: Tx; +- Receive data stream: Rx. + +The data flow signal description is presented in Table 8-1. + +The Tx and Rx data rate values are set during initialization as described in clause 12.3.5.2.1. The bit order in the data flow shall provide that the most significant bit (MSB) of the TPS-TC data is sent to the PMS-TC first. This bit convention is clarified for the ATM-TC in Figure L.8 and for the PTM-TC in clause N.3.4 of [ITU-T G.992.3], and for the MPS-TC in clauses 8.2.3 and 9.5.2.2. + +#### 8.1.2.2 Synchronization flow + +This flow provides synchronization between the TPS-TC sublayer and the PMS-TC sublayer. The synchronization flow comprises the two synchronization signals presented in Table 8-1: + +- Transmit and receive data flow octet-synchronization (Osync\_t, Osync\_r). + +All synchronization signals are asserted by the PMS-TC and directed towards the TPS-TC. The signals Osync\_t and Osync\_r determine the octet boundaries and the rates of the corresponding Tx and Rx data signals. In the case that the clock rate provided by the PMS-TC changes due to a reconfiguration, this change shall occur at an octet boundary, and shall be determined by the corresponding change in the Osync signal. The detailed description of the reconfiguration for specific TPS-TCs is in Annex L. + +#### 8.1.2.3 Control flow + +This flow provides a time marker (Syncflag, as specified in Table 8-1) for changes of the TPS-TC parameters (see clauses L.1.11.1, L.2.11.1, and L.3.11.1). The Syncflag is asserted by the PMS-TC and indicates a specific time when the TPS-TC shall start operating with modified parameters. + +### 8.1.3 Control parameters + +The configuration of the TPS-TC functions is controlled by a set of control parameters. Some of the control parameters are defined in Table 8-2. The remaining control parameters are dependent on the TPS-TC type and are defined in Annex L. + +**Table 8-2 – TPS-TC parameters** + +| Parameter | Definition | +|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $N_{BC}$ | The number of enabled transmit TPS-TC functions and the number of enabled bearer channels. The TPS-TC functions and bearer channels are labelled #0, #1. $N_{BC}$ is the number of non-zero values in the $\{type_0, type_1\}$ set. The value of $N_{BC}$ may be different for the VTU-O and VTU-R transmitters. | +| $type_n$ | The TPS-TC type mapped to bearer channel # $n$ ( $n = 0$ to $1$ ). The type of the specific TPS-TC shall be set to a value described in Annex L ( $type_n = 1$ (STM), $type_n = 2$ (ATM), or $type_n = 3$ (PTM)). The $type_n$ value of zero shall be used to disable TPS-TC function # $n$ and bearer channel # $n$ . | + +The values of all control parameters listed in Table 8-2 shall be configured during the channel analysis and exchange phase of initialization (see clause 12.3.5), using the O-TPS SOC message (see Tables 12-6 and 12-51). + +#### 8.1.3.1 Valid configurations + +A VTU may support two simultaneous TPS-TC functions in each direction. The control parameter $N_{BC}$ shall be in the 1 to 2 range. + +The valid values of the control parameter $type_n$ shall be those contained within Annex L or the value zero. All other values are reserved for use by ITU-T. If the $type_n$ parameter is non-zero for upstream and downstream, then it shall have the same value for upstream and downstream. + +A VTU shall support mapping of all supported TPS-TC types to all supported bearer channels, except that PTM on one bearer channel and ATM on the other bearer channel shall not be enabled simultaneously. The valid labelling of supported bearer channels shall start from 0 and increase by one. Thus, there are only two cases: + +- Single bearer channel mode: support of at least one TPS-TC function (of a type defined in Annex L) and one bearer channel. For this mode, bearer channel #0 shall be enabled. +- Dual bearer channel mode: support of at least two TPS-TC functions (of a type defined in Annex L) and two bearer channels. For this mode, bearer channels #0 and #1 shall be enabled. + +#### 8.1.3.2 Mandatory configurations + +A VTU shall support single bearer channel mode in the downstream direction. + +A VTU shall support single bearer channel mode in the upstream direction. + +## 8.2 Management TPS-TC (MPS-TC) + +The MPS-TC is intended to facilitate transport of eoc data between the VDSL2 management entities (VME-O, VME-R) at opposite ends of the VDSL2 link (see Figure 5-1). + +### 8.2.1 Functional model + +The MPS-TC shall provide fully-transparent eoc data transfer between the $\gamma_{m-O}$ and $\gamma_{m-R}$ interfaces (in the absence of non-correctable errors in the lower sublayers), and packet integrity of the transported eoc messages (commands and responses). In the transmit direction, the MPS-TC gets the eoc message from the VME over the application interface ( $\gamma_m$ interface), encapsulates it using the high-level data link control (HDLC) frame format, and submits it to the $\alpha/\beta$ interface to be transported via the VDSL2 link using the PMS-TC overhead messaging channel specified in clause 9.5.2. In the receive direction, the MPS-TC delineates the HDLC frames, runs the frame check sequence (FCS) check, and extracts the encapsulated eoc message from the correctly received HDLC frames. The received eoc messages are submitted to the VME over the $\gamma_m$ interface. All incorrectly received HDLC frames shall be discarded. + +NOTE – If the PMS-TC operates in dual latency mode (see clause 9.1), the encapsulated eoc messages are carried in the latency path which is determined by the control variable in the MSGLP field. This value is set during initialization in accordance with the type of OH frame being used, as specified in clauses 9.5.2.2 and 12.3.5.2.1.3. + +### 8.2.2 Interface description + +#### 8.2.2.1 $\gamma$ interface + +The $\gamma_{m-O}$ and $\gamma_{m-R}$ reference points define interfaces between the VME and the MPS-TC at the VTU-O and VTU-R respectively, as shown in Figure 5-1. Both interfaces are identical, functional, and are defined by three signal flows between the VME and the MPS-TC: + +- 1) Data flow; +- 2) Synchronization flow; and +- 3) Control flow. + +The various signals are summarized in Table 8-3. + +**Table 8-3 – MPS-TC: $\gamma_m$ interface data, synchronization and control flows signal summary** + +| Flow | Signal | Description | Direction | +|-------------------------|----------------|-------------------------------------------------------------------------------------|--------------| +| Transmit signals | | | | +| Data | Tx_eoc | Transmit data | VME → MPS-TC | +| Sync | Tx_Avbl | Asserted by the VME if the message is available for transmission | VME → MPS-TC | +| Sync | Tx_Clk | Transmit clock | VME → MPS-TC | +| Sync | Tx_SoM | Start of the transmit message | VME → MPS-TC | +| Sync | Tx_EoM | End of the transmit message | VME → MPS-TC | +| Control | Tx_stop | Interruption of the transmission of the message | VME → MPS-TC | +| Control | Tx_RF | Response flag | VME → MPS-TC | +| Control | Tx_PrF | Priority flag | VME → MPS-TC | +| Control | Sent | Sent flag | VME ← MPS-TC | +| Receive signals | | | | +| Data | Rx_eoc | Receive data | VME ← MPS-TC | +| Sync | Rx_Enbl | Asserted by the MPS-TC; indicates that the VME may pull the message from the MPS-TC | VME ← MPS-TC | + +**Table 8-3 – MPS-TC: $\gamma_m$ interface data, synchronization and control flows signal summary** + +| Flow | Signal | Description | Direction | +|-------------------------|---------------|------------------------------|--------------| +| Transmit signals | | | | +| Sync | Rx_ClK | Receive clock | VME → MPS-TC | +| Sync | Rx_SoM | Start of the receive message | VME ← MPS-TC | +| Sync | Rx_EoM | End of the receive message | VME ← MPS-TC | +| Control | Rx_RF | Response flag | VME ← MPS-TC | +| Control | Rx_PrF | Priority flag | VME ← MPS-TC | + +##### 8.2.2.1.1 Data flow + +The data flow shall consist of two contra-directional octet-based streams of messages with variable length: transmit messages (*Tx\_eoc*) and receive messages (*Rx\_eoc*). Bits within each octet are labelled $a_1$ through $a_8$ , with $a_1$ being the least significant bit (LSB) and $a_8$ being the MSB. Octets are labelled in numeric order. The VME shall send the eoc message to the MPS-TC with bit $a_1$ of the first octet sent first. The data flow signal description is presented in Table 8-3. + +##### 8.2.2.1.2 Synchronization flow + +This flow provides synchronization between the VME and the MPS-TC and contains the necessary timing to provide integrity of the transported message. The synchronization flow shall consist of the following signals presented in Table 8-3: + +- Transmit and receive timing signals (*Tx\_ClK*, *Rx\_ClK*): both asserted by the VME; +- Start of message signals (*Tx\_SoM*, *Rx\_SoM*): asserted by the VME and by the MPS-TC, respectively, to mark the beginning of the transported message in the corresponding direction of transmission; +- End of message signals (*Tx\_EoM*, *Rx\_EoM*): asserted by the VME and by the MPS-TC, respectively, to mark the end of the transported message in the corresponding direction of transmission; +- Transmit packet available signals (*Tx\_AvbI*): asserted by the VME to indicate that the message is ready for transmission; and +- Enable receive signal (*Rx\_Enbl*): asserted by the MPS-TC to indicate that the data packet may be pulled from the MPS-TC by the VME. + +##### 8.2.2.1.3 Control flow + +This flow provides priority management of the sent messages, and consists of the following signals presented in Table 8-3: + +- Stop transmission (*Tx\_Stop*): asserted by the VME to indicate that the MPS-TC shall stop the transmission of the current message (to release the channel for a message with higher priority); +- Response flag (*Tx\_RF*, *Rx\_RF*): asserted by the VME and MPS-TC, respectively, to indicate that the eoc message contains a response; +- Priority flag (*Tx\_PrF*, *Rx\_PrF*): asserted by the VME and MPS-TC, respectively, to indicate the priority level of the command carried by the eoc message; and +- Sent flag (*Sent*): asserted by the MPS-TC to mark the time the last octet of the HDLC frame was sent over the $\alpha/\beta$ interface. + +#### 8.2.2.2 $\alpha/\beta$ interface + +The $\alpha$ and $\beta$ reference points define interfaces between the MPS-TC and PMS-TC at the VTU-O and VTU-R, respectively. Both interfaces are functional and shall comply with the definition for user TPS-TC as specified in clause 8.1.2. The MPS-TC shall ignore the Syncflag signal; the parameters of the MPS-TC are not subject to on-line reconfiguration. + +### 8.2.3 Encapsulation format + +The MPS-TC shall encapsulate messages for transmission using an HDLC-based frame format as shown in Table 8-4. + +**Table 8-4 – HDLC frame structure** + +| Octet # | MSB | LSB | +|---------|---------------------------------|-----| +| | 7E 16 – Opening flag | | +| 1 | Address field | | +| 2 | Control field | | +| 3 | Message octet #1 | | +| ... | .... | | +| $P + 2$ | Message octet # $P$ | | +| $P + 3$ | FCS high octet | | +| $P + 4$ | FCS low octet | | +| | 7E 16 – Closing flag | | + +The MSB of octets of the encapsulated message shall be the MSB of the corresponding octet in the HDLC frame. The first octet of the eoc message incoming from the $\gamma$ interface shall be transmitted first and the MSB of each octet shall be transmitted first. + +### 8.2.4 Communication protocol + +#### 8.2.4.1 Transmitter + +The transmitter shall encapsulate eoc messages prior to transmission using the HDLC frame structure described in clause 8.2.3. The FCS, the octet transparency mechanism, and HDLC inter-frame time filling shall be as described in [ITU-T G.997.1]. Opening and closing flags of two adjacent HDLC frames may be shared: the closing flag of one frame can serve as an opening flag for the subsequent frame. + +If a *Tx\_Stop* signal is set, the transmitter shall stop the transmission of the current message using the abort sequence described in [ITU-T G.997.1] (i.e., by a control escape octet followed by a flag), and get ready to receive a new message from the VME to be transmitted. If the transmission of the message is already completed when a *Tx\_Stop* signal is set, the MPS-TC shall ignore it. + +The transmitter shall set the two LSBs of the Address field in accordance with the priority level of the command sent, indicated by the *Tx\_PrF* signal, as follows: + +- 00 – High priority; +- 01 – Normal priority; +- 10 – Low priority; +- 11 – Near high priority. + +All other bits of the Address field shall be set to ZERO. + +The transmitter shall set the second LSB of the Control field with a command code (0) or a response code (1), in accordance with the signal *Tx\_RF*. All other bits of the Control field shall be set to ZERO. + +Upon the completion of the transmission of the HDLC frame, the transmitter shall set the *Sent* signal, indicating to the VME the start of the time-out timer (see Table 11-1). + +#### 8.2.4.2 Receiver + +The receiver shall search for octet boundaries of HDLC frames. All incorrectly received frames, including invalid frames described in [ITU-T G.997.1] and frames with an invalid FCS, shall be discarded. Frames with an Address field or Control field not meeting the HDLC frame structure described in clauses 8.2.3 and 8.2.4.1 shall be discarded. + +The MPS-TC shall extract the encapsulated eoc commands/responses from the correctly received HDLC frames and send them to the VME via the $\gamma_m$ interface. + +The receiver shall use the second LSB of the Control field of the received HDLC frame to distinguish between commands and responses and shall set the Response flag *Rx\_RF* accordingly. The receiver shall use the last two LSBs of the Address field to identify the priority of the eoc command carried by the received HDLC frame and shall set the Priority flag *Rx\_PrF* accordingly. Both *Rx\_RF* and *Rx\_PrF* shall be asserted upon the arrival of a valid HDLC header, which includes an Opening Flag, Address field and Control field (see Table 8-4), before the FCS verification of the received HDLC frame, to indicate the arrival time of the eoc message. After the FCS has been verified, the receiver shall set the *Rx\_Enbl* signal to indicate that the correctly-received packet is ready. + +NOTE – The VME uses the received Priority flag of the response messages to determine their arrival times and decide whether the response eoc message meets the time-out. Use by the VME of the received Priority flag of the command messages is currently undefined. + +## 8.3 Network timing reference TPS-TC (NTR-TC) + +Transport of an 8 kHz NTR from the VTU-O to the VTU-R shall be supported in order to support isochronous services that require the same exact timing reference at both sides of the VDSL2 line to operate the higher layers of the protocol stack. The VTU-O shall indicate NTR transport during initialization (see clause 12.3.5.2.1.1). + +### 8.3.1 Interfaces + +The $\gamma_{m-O}$ and $\gamma_{m-R}$ reference points define interfaces between the NTR source and the NTR-TC at the VTU-O and between the NTR-TC and the NTR receiver at the VTU-R, respectively, as shown in Figure 5-1. Both interfaces are identical, functional, and are defined by the signals specified in Table 8-5. + +**Table 8-5 – NTR-TC: $\gamma$ interface signal summary** + +| Flow | Signal | Description | Direction | +|---------------------------------|---------------|---------------------|-----------------------| +| Transmit signals (VTU-O) | | | | +| NTR | Tx_NTR | Transmit NTR signal | NTR source → NTR-TC | +| Receive signals (VTU-R) | | | | +| NTR | Rx_NTR | Receive NTR signal | NTR receiver ← NTR-TC | + +The $\alpha$ and $\beta$ reference points define interfaces between the NTR-TC and PMS-TC at the VTU-O and VTU-R, respectively. Both interfaces are functional, and shall comply with the definition in clause 8.1.2 with the additional condition that NTR data is transmitted only in the direction from the VTU-O to the VTU-R. The NTR-TC shall ignore the Syncflag signal; the parameters of NTR-TC are not subject to on-line reconfiguration. + +### 8.3.2 Functionality + +NTR transport is facilitated by the NTR-TC. At the VTU-O the NTR-TC encodes the incoming NTR signal transitions into the NTR byte to be transported over the VDSL2 link in the NTR field of the OH frame. At the VTU-R the NTR-TC extracts the NTR byte from the OH frame and reconstructs the NTR signal. + +The NTR-TC at the VTU-O shall generate the NTR bytes in the following way. The VTU-O shall derive a local 8 kHz local timing reference (LTR) by dividing its sampling clock by the appropriate number. Further, the VTU-O shall estimate the change in phase offset between the NTR and the LTR from the previous OH frame to the present OH frame (see clause 9.5.2). The change in phase offset shall be estimated at the beginning of the OH frame. The estimated value shall be expressed in cycles of the sampling clock running at frequency $8\,192 \times \Delta f$ and shall be mapped to the NTR byte as a 2-complement number. + +The bits of the NTR byte, denoted by $ntr_7$ to $ntr_0$ , represent a signed integer in the range between $-128$ to $+127$ . A positive value of the change in phase offset ( $ntr_7$ is set to ZERO) indicates that the LTR has a higher frequency than the NTR; a negative value of the change in phase offset ( $ntr_7$ is ONE) indicates that the LTR has a lower frequency than the NTR. The $ntr$ bits shall all be set to ZERO if the VTU-O locks its' transmit PMD clock to the NTR frequency. + +The NTR byte is transported in the NTR field of the OH frame. The mapping of the $ntr$ bits to the NTR field of the OH frame is specified in clause 9.5.2.2. + +The NTR-TC at the VTU-R shall reconstruct the 8 kHz NTR from the received values of the NTR byte using the encoded changes in the phase offset. + +NOTE – In VDSL2, the sampling clock is proportional to the subcarrier spacing $\Delta f$ . Therefore, the LTR, being proportional to the sampling clock, will have the same $\pm 50$ ppm frequency variation as $\Delta f$ (see clause 10.4.2). The NTR has a maximum variation of $\pm 32$ ppm, thus the maximum difference in frequency between the NTR and the LTR will not exceed 82 ppm. This would result in a maximum time offset of $82 \times 10^{-6} \times PER_p$ , where $PER_p$ is the duration of the OH frame as defined in clause 9.5.4. This corresponds to $(82 \times 10^{-6} \times PER_p) \times 8\,192 \times \Delta f$ sampling cycles, which, for a subcarrier spacing of 4.3125 kHz, is equal to $2\,896 \times PER_p$ sampling cycles. With the maximum value of $PER_p$ , which is less than 20 ms (see Table 9-8), the value of the offset to be transmitted will not exceed $\pm 58$ . Therefore, the one-byte information field reserved for NTR is sufficient. + +## 8.4 Time-of-day TPS-TC (ToD-TC) + +Transport of time-of-day (ToD) from the VTU-O to the VTU-R should be supported in order to support services that require accurate ToD at both sides of the VDSL2 line to operate the higher layers of the protocol stack. The VTU-O shall indicate ToD transport during initialization (see clause 12.3.5.2.1.1). + +NOTE 1 – Exchange of network time management information from VTU-R to VTU-O related to the quality of the ToD frequency and/or time recovery at the VTU-R is for further study. + +NOTE 2 – Exchange of relevant clock information from AN to CPE to support the ToD interface output from CPE is for further study. For PTP, this information includes source traceability, number of hops, and leap seconds. + +NOTE 3 – The $\gamma$ -O to $\gamma$ -R ToD accuracy requirements are for further study; it is expected however, to be on the order of 100/200 ns. + +### 8.4.1 Time-of-day distribution operational overview + +Figure 8-1 shows the system reference model identifying the key elements in support of time-of-day transport across a VDSL2 link. The VTU-O receives a time-of-day signal from the master clock across the $\gamma$ -O interface and the VTU-R outputs a time-of-day signal across the $\gamma$ -R interface to slave clock external to the VTU-R that is synchronous in frequency, phase and time to the master clock. A + +master clock source external to the VTU-O provides a time-of-day signal to the VTU-O across the $\gamma$ -interface. The details of the time-of-day signal are for further study; however, the components include a time-of-day value (*ToD\_mc\_value*) to a corresponding clock edge (*ToD\_mc\_edge*) that is synchronous to the master clock's internal driving frequency. The *ToD\_mc\_edge* shall provide at least one edge per second. A component of the driving frequency (*fmc*) shall be available to the VTU-O and shall be at least 8 kHz and shall be frequency and phase synchronized with the *ToD\_mc\_edge* to facilitate time-of-day transport processing in the VTU-O. Similarly, the time-of-day signal at the VTU-R is assumed to include a time-of-day value (*ToD\_sc\_value*) together with corresponding time edge marker (*ToD\_sc\_edge*) that is synchronous to the driving frequency of the master clock. A component of the driving frequency (*fsc*) may be available from the VTU-R to facilitate time-of-day transport processing. + +![Figure 8-1: End-to-end system reference model for time-of-day transport in VDSL2. The diagram shows a 'Central office (VTU-O) location' on the left and a 'Remote (VTU-R) location' on the right, connected by a 'Subscriber line'. At the VTU-O, a 'Master clock' provides 'ToD_mc_value', 'ToD_mc_edge', and 'f_mc' to a 'ToD-TC' block. The 'ToD-TC' block connects to a 'PMS-TC and PMD' block via a 'gamma-O' interface. The 'PMS-TC and PMD' block is connected to the 'Subscriber line' (U-O side) and has a 'PMD sampling clock' (f_s) input. The 'Subscriber line' (U-R side) connects to another 'PMS-TC and PMD' block. This block receives a 'Recovered PMD sampling clock' (f_s) from a '(Loop timing)' block and connects to a 'ToD-TC' block via a 'gamma-R' interface. The 'ToD-TC' block provides 'ToD_sc_value', 'ToD_sc_edge', and 'f_sc' to a 'Slave clock'. Various timing parameters t1, t2, t3, t4 are indicated on the subscriber line. The diagram is labeled G.993.2(15)/F8-1.](fee87ee34f98efee162e918fbaeec613_img.jpg) + +Figure 8-1: End-to-end system reference model for time-of-day transport in VDSL2. The diagram shows a 'Central office (VTU-O) location' on the left and a 'Remote (VTU-R) location' on the right, connected by a 'Subscriber line'. At the VTU-O, a 'Master clock' provides 'ToD\_mc\_value', 'ToD\_mc\_edge', and 'f\_mc' to a 'ToD-TC' block. The 'ToD-TC' block connects to a 'PMS-TC and PMD' block via a 'gamma-O' interface. The 'PMS-TC and PMD' block is connected to the 'Subscriber line' (U-O side) and has a 'PMD sampling clock' (f\_s) input. The 'Subscriber line' (U-R side) connects to another 'PMS-TC and PMD' block. This block receives a 'Recovered PMD sampling clock' (f\_s) from a '(Loop timing)' block and connects to a 'ToD-TC' block via a 'gamma-R' interface. The 'ToD-TC' block provides 'ToD\_sc\_value', 'ToD\_sc\_edge', and 'f\_sc' to a 'Slave clock'. Various timing parameters t1, t2, t3, t4 are indicated on the subscriber line. The diagram is labeled G.993.2(15)/F8-1. + +**Figure 8-1 – End-to-end system reference model for time-of-day transport in VDSL2** + +The VDSL2 PMD operates with a sampling clock for transmission of the DMT symbols on the subscriber line. The VTU-R's PMD sampling clock and the VTU-O's PMD sampling clock are assumed to be frequency locked, typically through loop timing in the VTU-R. For both the upstream and downstream transmit signals, the reference sample is defined as the first time-domain representation sample (see Figure 8-2 and Figure 8-3) of the first symbol in a superframe period (64.25 ms on the PMD sampling clock timebase if the CE length corresponds to *m* = 5, see clause 10.4.4). + +![Figure 8-2: Cyclic extension, windowing and overlap of DMT symbols. The diagram illustrates the timing of DMT symbols. It shows 'Sync symbol of superframe s-1' followed by 'Data symbol 0 of superframe s'. The 'Data symbol 0' consists of '2N samples' with a cyclic extension. The cyclic extension length is 'L_CS'. The guard interval length is 'L_CP'. The total duration of one symbol is '2N + L_CP + L_CS - beta samples'. The 'reference sample' is identified as 'the first sample in the block of 2N samples'. The 'event t_n occurs when reference sample crosses U-x reference point'. The diagram includes windowing and overlap parameters 'beta' and 'L_CS'. The diagram is labeled G.993.2(15)_F8-2.](212c50c4e3d043c989037a01e13c1a98_img.jpg) + +Figure 8-2: Cyclic extension, windowing and overlap of DMT symbols. The diagram illustrates the timing of DMT symbols. It shows 'Sync symbol of superframe s-1' followed by 'Data symbol 0 of superframe s'. The 'Data symbol 0' consists of '2N samples' with a cyclic extension. The cyclic extension length is 'L\_CS'. The guard interval length is 'L\_CP'. The total duration of one symbol is '2N + L\_CP + L\_CS - beta samples'. The 'reference sample' is identified as 'the first sample in the block of 2N samples'. The 'event t\_n occurs when reference sample crosses U-x reference point'. The diagram includes windowing and overlap parameters 'beta' and 'L\_CS'. The diagram is labeled G.993.2(15)\_F8-2. + +**Figure 8-2 – Cyclic extension, windowing and overlap of DMT symbols** + +The VDSL2 PMD in the VTU-O identifies the moment the downstream reference sample crosses the U-O interface (event $t_1$ ) and the moment (within one superframe from event $t_1$ ) the upstream reference sample crosses the U-O interface (event $t_4$ ); at the instant each event occurs, the ToD-TC (time-of-day – transmission convergence) in the VTU-O records the corresponding time values of its local real-time clock (RTC-O) to apply a time stamp to each of the respective events $t_1$ and $t_4$ . For each event $t_1$ , the VTU-O sends the ToD phase difference (i.e., the corresponding $t_1$ time stamp MOD 125 000 ns, represented in units of 2 ns) and the $t_1$ event number (i.e., representing the superframe counter value at the $t_1$ event) to the VTU-R. The VTU-R processes the ToD phase difference values to recover the ToD frequency. At a much slower rate, the VTU-O also sends the $t_1$ and $t_4$ time stamps together with a $t_1$ and $t_4$ event number to VTU-R for time/phase synchronization of the real time clocks. Similarly, the VDSL2 PMD in the VTU-R identifies the moment the downstream reference sample crosses the U-R interface (event $t_2$ ) and the upstream reference sample crosses the U-R interface (event $t_3$ ); at the instant each event occurs, the ToD-TC in the VTU-R records the corresponding time of the local slave clock to apply a time stamp to each of the respective events $t_2$ and $t_3$ . The ToD-TC in the VTU-R processes the time stamp values of events $t_1$ , $t_2$ , $t_3$ , and $t_4$ so as to synchronize in phase and time its local real-time clock (RTC-R) to the VTU-O's real-time clock (RTC-O). + +NOTE 1 – The time period between consecutive reference samples is fixed and equal to the number of samples in a super-frame. This time period is therefore locked to the VTU's PMD sampling clock. With this relation, the time stamp values are recorded at regularly repeating intervals. + +NOTE 2 – The VTU-R sends the values of events $t_2$ and $t_3$ to the VTU-O in response to a VTU-O command sending the corresponding $t_1$ and $t_4$ event values for phase/time synchronization. + +![Timing diagram showing reference samples and time stamp events t1, t2, t3, and t4 across four signal paths: VTU-O: Tx DS, VTU-R: Rx DS, VTU-R: Tx US, and VTU-O: Rx US. The diagram illustrates the sequence of symbols (Sync, 1st Data, Reference) and the 256 Data symbols per superframe. Time intervals Δ_DS, ε (Note), Δ_US, and Superframe T_SF = 64.25 ms are indicated.](fd3cbb53e991f8209ba17b398f426e13_img.jpg) + +The diagram illustrates the timing of reference samples and time stamp events across four signal paths: + +- VTU-O: Tx DS**: Shows a sequence of symbols starting with a Sync symbol, followed by the 1st Data symbol, and a Reference sample. This is followed by 256 Data symbols. The event $t_1$ (DS ref. sample crosses U-O interface) is marked at the start of the Reference sample. +- VTU-R: Rx DS**: Shows the same sequence of symbols. The event $t_2$ (DS ref. sample crosses U-R interface) is marked at the start of the Reference sample. The time interval between $t_1$ and $t_2$ is labeled $\Delta_{DS}$ . +- VTU-R: Tx US**: Shows the same sequence of symbols. The event $t_3$ (US ref. sample crosses U-R interface) is marked at the start of the Reference sample. The time interval between $t_2$ and $t_3$ is labeled $\varepsilon$ (Note). +- VTU-O: Rx US**: Shows the same sequence of symbols. The event $t_4$ (US ref. sample crosses U-O interface) is marked at the start of the Reference sample. The time interval between $t_3$ and $t_4$ is labeled $\Delta_{US}$ . + +The time interval between $t_1$ and $t_4$ is labeled Superframe $T_{SF} = 64.25$ ms. The diagram also includes the text "NOTE – $\varepsilon$ may be a positive or a negative time" and the reference "G.993.2(15)\_F8-3". + +Timing diagram showing reference samples and time stamp events t1, t2, t3, and t4 across four signal paths: VTU-O: Tx DS, VTU-R: Rx DS, VTU-R: Tx US, and VTU-O: Rx US. The diagram illustrates the sequence of symbols (Sync, 1st Data, Reference) and the 256 Data symbols per superframe. Time intervals Δ\_DS, ε (Note), Δ\_US, and Superframe T\_SF = 64.25 ms are indicated. + +**Figure 8-3 – Reference samples and corresponding time stamp events $t_1$ , $t_2$ , $t_3$ and $t_4$** + +The ToD-TC in the VTU-O and that in the VTU-R implement functionality with the objective of synchronizing the RTC-R to the RTC-O in frequency, phase and time. Two methods are defined to achieve this objective: + +- 1) Frequency synchronization through locking the PMD sampling clock with the ToD frequency ( $f_{mc}$ ): the VTU-R achieves frequency synchronization through loop timing and performs phase/time synchronization through the processing of time stamps at reference samples; or +- 2) Frequency synchronization using ToD phase difference values: the VTU-R achieves frequency synchronization through processing of ToD phase difference values (i.e., phase of $t_1$ event relative to ToD) and performs phase/time synchronization through the processing of time stamps (of events $t_1$ , $t_2$ , $t_3$ , and $t_4$ ) at the reference samples. + +The frequency synchronization method adopted in the VTU-O is communicated to the VTU-R during initialization (see clause 12.3.5.2.1.2). For each of the above cases, the corresponding functional processing is described. + +The block diagram in Figure 8-4 shows a functional model of the required processing in the VTU-O ToD-TC. The ToD-TC receives the time-of-day signals from the master clock and assigns time stamps to reference samples per the Real-time Clock (RTC-O), that is synchronous to the external master clock time base. + +In the VTU-O, the ToD-TC implements a Real-time Clock (RTC-O) that is synchronized to the external master clock for the purpose of applying time stamps to the reference samples. The VDSL2 PMD identifies the moment that the reference samples cross the U-O interface; the Reference Sample Timing block generates pulses $t_1$ and $t_4$ , for reading the value of the RTC-O clock in recording of the respective time stamps for the downstream and upstream reference samples. The time stamp values, $ToD(t_1)$ and $ToD(t_4)$ together with the reference sample identification (event number) are sent to the VTU-R via the eoc. + +In the VTU-R, frequency synchronization of the RTC-R clock to the RTC-O clock in the VTU-O may be performed using any of the two methods mentioned above; the frequency synchronization method is selected by the VTU-O during initialization (see clause 12.3.5.2.1.2). Shown in Figure 8-4 is the method of computing phase difference values for frequency synchronization of the Real-time Clock in the VTU-R (RTC-R) with the RTC-O. Phase difference values may be transported to the VTU-R via dedicated bytes in the OH Frame (see clause 9.5.2.2.1) or via the eoc (see clause 11.3.2.14); the transport method is selected by the VTU-R during initialization (see clause 12.3.5.2.2.1). The time stamp values for ToD phase synchronization (i.e., $ToD(t_1)$ and $ToD(t_4)$ ) are transported to the VTU-R by dedicated eoc commands (see clause 11.2.3.15). + +![Figure 8-4: Functional reference model for ToD-TC in the VTU-O. The diagram shows a Master clock providing ToD_tx_value, ToD_tx_edge, and f_mc signals to a Timestamp processing block. The Timestamp processing block contains a Real-time clock (RTC-O) and generates ToD(t4) and ToD(t1) signals. The RTC-O also provides t4 and t1 signals to a Reference sample timing block. The Reference sample timing block generates t4 ToD_Seqnr and t1 ToD_Seqnr signals. These are processed by Mod 256 and Mod 64 blocks to generate t4_event_nr and t1_event_nr signals. The t1_event_nr signal is also processed by a Mod 125000 ns DIV 2 (ns) block to generate a Phase diff signal. The PMD sampling clock (Note) is used for implementation of the RTC-O. The output signals are sent in eoc at least once every TSP t1 events or in OH frame or eoc each t1 event.](cc542843836eecb036b99cb270b54a1e_img.jpg) + +The diagram illustrates the functional reference model for the ToD-TC in the VTU-O. On the left, a 'Master clock' provides three signals: 'ToD\_tx\_value', 'ToD\_tx\_edge', and $f_{mc}$ . These signals enter a 'Timestamp processing' block, which contains a 'Real-time clock (RTC-O)'. The RTC-O outputs 'ToD( $t_4$ )' and 'ToD( $t_1$ )' signals. It also receives 't4' and 't1' signals from a 'Reference sample timing' block. The 'Reference sample timing' block generates 't4 ToD\_Seqnr' and 't1 ToD\_Seqnr' signals. 't4 ToD\_Seqnr' is processed by a 'Mod 256' block to produce 't4\_event\_nr'. 't1 ToD\_Seqnr' is processed by a 'Mod 64' block to produce 't1\_event\_nr'. 't1\_event\_nr' is also processed by a 'Mod 125000 ns DIV 2 (ns)' block to produce a 'Phase diff' signal. A 'PMD sampling clock (Note)' is input to the RTC-O. The output signals ('ToD( $t_4$ )', 'ToD( $t_1$ )', 't4\_event\_nr', 't1\_event\_nr', and 'Phase diff') are sent to the right, with annotations indicating they are 'Sent in eoc at least once every TSP $t_1$ events' or 'Sent in OH frame or eoc each $t_1$ event'. The diagram is bounded by vertical dashed lines labeled $\gamma$ -O and $\alpha$ . + +Figure 8-4: Functional reference model for ToD-TC in the VTU-O. The diagram shows a Master clock providing ToD\_tx\_value, ToD\_tx\_edge, and f\_mc signals to a Timestamp processing block. The Timestamp processing block contains a Real-time clock (RTC-O) and generates ToD(t4) and ToD(t1) signals. The RTC-O also provides t4 and t1 signals to a Reference sample timing block. The Reference sample timing block generates t4 ToD\_Seqnr and t1 ToD\_Seqnr signals. These are processed by Mod 256 and Mod 64 blocks to generate t4\_event\_nr and t1\_event\_nr signals. The t1\_event\_nr signal is also processed by a Mod 125000 ns DIV 2 (ns) block to generate a Phase diff signal. The PMD sampling clock (Note) is used for implementation of the RTC-O. The output signals are sent in eoc at least once every TSP t1 events or in OH frame or eoc each t1 event. + +NOTE – Use of the PMD sampling clock for implementation of the RTC-O is vendor discretionary. + +G.993.2(15)F8-4 + +**Figure 8-4 – Functional reference model for ToD-TC in the VTU-O** + +During initialization, the VTU-O indicates to the VTU-R the configured ToD frequency synchronization method, namely via locking of the VDSL PMD sampling clock to the ToD frequency or via transport of phase difference values. If the VTU-O selects the locking of the PMD sampling clock to the ToD frequency, then the VTU-R achieves ToD frequency synchronization through normal loop timing recovery. If the VTU-O selects the mechanism of passing phase difference values to the VTU-R for ToD frequency synchronization, then the VTU-R selects the mechanism for which the VTU-O is to communicate the phase difference values: i.e., via dedicated fixed octets in the OH frame, or via phase difference messages communicated in the eoc. In either case, time synchronization is provided through processing of the time synchronization messages communicated to the VTU-R by the VTU-O. + +In the VTU-R the ToD-TC processes the time stamp values placed on the downstream (event $t_2$ ) and upstream (event $t_3$ ) reference samples together with those values received from the VTU-O for events $t_1$ and $t_4$ to achieve phase/time synchronization of the RTC-R to the RTC-O. The ToD-TC then outputs a time-of-day value (ToD\_sc\_value) together with a corresponding timing edge marker (ToD\_sc\_edge) that is synchronous to the driving master clock frequency. The ToD\_sc\_value and ToD\_sc\_edge signals (and possibly a slave clock frequency $f_{sc}$ ) are transported across the $\gamma$ -R interface to a device external to the VTU-R. The time stamp values placed on the downstream (event $t_2$ ) and upstream (event $t_3$ ) reference samples are sent back to the VTU-O (see clause 11.2.3.15). The VTU-O passes information related to these time stamps over the $\gamma$ -O reference point. The nature and use of this information is for further study. + +The time-of-day (phase) synchronization of the RTC-R to the RTC-O, is done in the ToD-TC in the VTU-R. The time stamp processing block reads the value of the local RTC-R as the downstream reference sample crosses the U-R reference point (event $t_2$ ) and upstream reference sample crosses the U-R reference point (event $t_3$ ), and assigns corresponding time stamp values ToD( $t_2$ ) and ToD( $t_3$ ). The computation of the offset value ( $\tau$ ) is computed from the reported time stamps using the following equation: + +$$\tau = \frac{(ToD(t_2) - ToD(t_1)) - (ToD(t_4) - ToD(t_3))}{2}$$ + +NOTE 3 – The above computation of the offset value is based on the assumption that the downstream and upstream propagation delays between the U-C and U-R reference points are approximately identical. Any asymmetry in the propagation delay between the U-C and U-R reference points will result in an error in calculation of the offset value whose magnitude is approximately: + +$$|error| = \left| \frac{(upstream\_propagation\_delay) - (downstream\_propagation\_delay)}{2} \right|$$ + +### 8.4.2 Interfaces + +The $\gamma_{m-O}$ and $\gamma_{m-R}$ reference points define interfaces between the ToD source and the ToD-TC at the VTU-O and between the ToD-TC and the ToD receiver at the VTU-R, respectively, as shown in Figure 5-1. Both interfaces are functionally identical, and are defined in Table 8-6. + +**Table 8-6 – ToD-TC: $\gamma$ interface signal summary** + +| Flow | Signal | Description | Direction | +|---------------------------------|---------------|-----------------------------|-----------------------| +| Transmit signals (VTU-O) | | | | +| ToD | Tx_ToD | Transmit time-of-day signal | ToD source → ToD-TC | +| Receive signals (VTU-R) | | | | +| ToD | Rx_ToD | Receive time-of-day signal | ToD receiver ← ToD-TC | + +The $\alpha$ and $\beta$ reference points define interfaces between the ToD-TC and PMS-TC at the VTU-O and VTU-R, respectively. Both interfaces are functional, and shall comply with the definition in clause 8.1.2 with the additional condition that ToD data is transmitted only in the direction from the VTU-O to the VTU-R. The parameters of ToD-TC are not subject to on-line reconfiguration. + +### 8.4.3 Functionality + +#### 8.4.3.1 Frequency Synchronization by locking PMD sampling clock with ToD frequency + +This clause defines a mechanism for frequency synchronization of the Real-time Clock in the VTU-R (RTC-R) with the Real-time Clock in the VTU-O (RTC-O) by locking the PMD sampling clock with the ToD frequency ( $f_{mc}$ ). The VTU-R shall achieve frequency synchronization between RTC-R and RTC-O through loop timing. + +#### 8.4.3.2 Frequency Synchronization using ToD phase difference values + +This clause defines a mechanism for frequency synchronization of the Real-time Clock in the VTU-R (RTC-R) with the Real-time Clock in VTU-O (RTC-O) by processing of the ToD phase difference values between the local super-frame clock (i.e., event $t_1$ ) and the ToD (i.e., RTC-O) clock. + +The Real-time Clock represents the time-of-day value with a 6 octet seconds field followed by a 4 octet nanosecond field, where the nanosecond field resets to zero every $10^9$ ns and the seconds field increments by one. + +Figure 8-5 demonstrates the computation of the ToD phase difference value ( $\Delta\phi$ ). The top row in the figure represents the counting of the nanoseconds in the RTC-O. The ToD nanoseconds counter counts the nanoseconds of the RTC-O modulo 125 $\mu\text{s}$ (shown by the 8 kHz waveform in the middle row of the figure). The third row in the figure represents the super-frame (SF) counter of the local clock that is synchronous with the VTU's PMD sampling clock; the rising edge of the SF local clock represents the moment that the downstream reference sample crosses the U-O reference point (i.e., the $t_1$ event). At the moment the downstream reference sample crosses the U-O reference point, the value of the ToD ns\_counter modulo 125 $\mu\text{s}$ is recorded as the 'ToD Phase Difference Value' to be communicated to the VTU-R. + +![Figure 8-5 – ToD phase difference (Δφ) computation. The diagram shows three horizontal timelines. The top timeline is 'ToD increment units (ns)' represented by a dense series of vertical lines. The middle timeline is 'ToD ns_counter mod 125 μs' represented by a square wave. A horizontal double-headed arrow between two rising edges of this square wave is labeled '125 μs'. The bottom timeline is 'Local clock (SF)' represented by a square wave. A vertical dashed line marks a 't1 event' at a rising edge of the local clock. Another vertical dashed line is positioned to the left of the t1 event. The horizontal distance between these two dashed lines is labeled 'Δφ = Phase difference'. To the right of the t1 event, the text 'Δφ = ToD ns_counter mod 125 μs' is present. In the bottom right corner, the text 'G.993.2(15)_F8-5' is visible.](7e5f8a1e5575ef87a54c9c091eaaa66d_img.jpg) + +Figure 8-5 – ToD phase difference (Δφ) computation. The diagram shows three horizontal timelines. The top timeline is 'ToD increment units (ns)' represented by a dense series of vertical lines. The middle timeline is 'ToD ns\_counter mod 125 μs' represented by a square wave. A horizontal double-headed arrow between two rising edges of this square wave is labeled '125 μs'. The bottom timeline is 'Local clock (SF)' represented by a square wave. A vertical dashed line marks a 't1 event' at a rising edge of the local clock. Another vertical dashed line is positioned to the left of the t1 event. The horizontal distance between these two dashed lines is labeled 'Δφ = Phase difference'. To the right of the t1 event, the text 'Δφ = ToD ns\_counter mod 125 μs' is present. In the bottom right corner, the text 'G.993.2(15)\_F8-5' is visible. + +**Figure 8-5 – ToD phase difference ( $\Delta\phi$ ) computation** + +The ToD phase difference value ( $\Delta\phi$ ) is calculated each $t_1$ event. The ToD phase difference value shall be represented by a 16-bit value, calculated as the ns\_counter value of the RTC-O mod 125 000 ns divided by 2, where the resolution of the LSB is 2 ns. Each $t_1$ event shall be counted modulo 64 (i.e., represented by a 6-bit value). The phase difference value (16 bits) and corresponding $t_1$ event value (6 bits) shall be communicated to the VTU-R either via the OH Frame (see clause 9.5.2.2.1) or via the eoc (see clause 11.2.3.14). During initialization (see clause 12.3.5.2.2.1), the VTU-R shall select the use of either the OH Frame or eoc for communication of ToD phase difference value and corresponding $t_1$ event value. + +#### 8.4.3.3 Time synchronization of real-time clocks + +Time-of-day (ToD) transport is facilitated by the ToD-TC. The VTU-O shall maintain a real-time clock at the optical network unit (ONU) (RTC-O) which is synchronized with the ToD signal. The VTU-R shall also maintain a real-time clock at the remote site (RTC-R) with an arbitrary initial time. The RTC-O shall run in a frequency which is an integer multiple of 8 kHz and is at least the PMD sampling frequency, with time adjustment to the master clock at each $f_{mc}$ edge (see Figure 8-1). At the VTU-O, the ToD-TC receives the ToD signal to synchronize RTC-O, generates time stamps using RTC-O, and transports these time stamps to the VTU-R with EOC messages. At the VTU-R, the ToD-TC generates time stamps using RTC-R, extracts the time stamps contained in the eoc messages sent from the VTU-O, estimates the time offset between RTC-O and RTC-R using the time stamps, adjusts RTC-R using the estimated time offset, and controls the output ToD signal. + +The time synchronization procedure is defined as follows. A downstream (or upstream) reference sample is defined as the first time-domain sample of specific symbols in the downstream (or upstream) direction during Showtime. + +- 1) At the VTU-O, a time stamp is taken by the ToD-TC when the downstream reference sample, being transmitted to the VTU-R, arrives at the U-C reference point (event $t_1$ ). The time-of-day corresponding to event $t_1$ is denoted by $ToD(t_1)$ ; +- 2) At the VTU-R, a time stamp is taken by the ToD-TC when the same downstream reference sample arrives at the U-R reference point (event $t_2$ ). The time-of-day corresponding to event $t_2$ is denoted by $ToD(t_2)$ ; +- 3) At the VTU-R, a time stamp is taken by the ToD-TC when the upstream reference sample, being transmitted to the VTU-O, arrives at the U-R reference point (event $t_3$ ). The time-of-day corresponding to event $t_3$ is denoted by $ToD(t_3)$ ; +- 4) At the VTU-O, a time stamp is taken by the ToD-TC when the same upstream reference sample arrives at the U-O reference point (event $t_4$ ). The time-of-day corresponding to event $t_4$ is denoted by $ToD(t_4)$ ; + +- 5) The time stamp values $ToD(t_1)$ and $ToD(t_4)$ are transmitted from the VTU-O to the VTU-R with eoc messages, the time stamp values $ToD(t_2)$ and $ToD(t_3)$ are transmitted from the VTU-R to the VTU-O with eoc messages (see clause 11.2.3.15). + +The VTU-O shall maintain a counter of the transmitted downstream super-frames since the VTU-O entered Showtime. Each time the first symbol in a downstream super-frame (i.e., the symbol modulating downstream data frame 0 per Figure 10-2) is sent, the value of the downstream super-frame counter shall be increased by 1. The downstream reference sample shall be the first time-domain representation sample of the first symbol in a downstream super-frame period (i.e., the first sample after the cyclic prefix of the symbol modulating data frame 0 as defined in Figure 10-14 and Figure 10-2). The index of the downstream reference sample shall be the index of the downstream super-frame it belongs to. The index of the first downstream reference sample (i.e., first $t_1$ event index) sent in Showtime shall be 0. + +The VTU-O shall maintain a counter of the received upstream super-frames since the VTU-R entered Showtime. Each time the first symbol in an upstream super-frame (i.e., the symbol modulating upstream data frame 0 per Figure 10-2) is sent, the value of the upstream super-frame counter shall be increased by 1. The upstream reference sample shall be the first time-domain sample of the first symbol in an upstream super-frame. The index of the upstream reference sample shall be the index of the upstream super-frame it belongs to. The index of the first upstream reference sample (i.e., first $t_4$ event index) sent in Showtime shall be 0. + +The VTU-O initiates a time synchronization procedure. The increment of the $t_1$ event index between any two consecutive time synchronization procedures shall not exceed the value of the parameter time synchronization period (*TSP*), which is indicated by the VTU-R during initialization (see clause 12.3.5.2.1.5). The $t_1$ event index shall be a multiple of 16 super-frames. + +After receiving both time stamp values $ToD(t_1)$ and $ToD(t_4)$ , the VTU-R shall compute the time offset *Offset* between the Real-time Clocks RTC-O and RTC-R as: + +$$Offset = (ToD(t_2) + ToD(t_3) - ToD(t_1) - ToD(t_4)) / 2$$ + +The RTC-R shall be adjusted with this estimated time offset *Offset* so that it is time synchronized with the RTC-O (i.e., the value of *Offset* for the next time synchronization procedure is expected to be 0). + +NOTE – Instead of taking the time stamp $ToD(t_1)$ for event $t_1$ (i.e., when the reference sample arrives at the U-O reference point), it is easier to implement by taking a time stamp – when the same reference sample arrives at the output of the inverse discrete Fourier transform (IDFT) of the VTU-O (event $t'_1$ ). This time stamp is denoted by $ToD(t'_1)$ . The time stamp $ToD(t_1)$ for event $t_1$ is obtained by adjusting the time stamp $ToD(t'_1)$ for event $t'_1$ with an estimate of $\Delta t_1 = ToD(t_1) - ToD(t'_1)$ . The method of adjustment is vendor discretionary. Instead of taking the time stamp $ToD(t_2)$ for event $t_2$ (i.e., when the reference sample arrives at the U-R reference point), it is easier to implement by taking a time stamp when the same reference sample arrives at the input of the DFT of the VTU-R (event $t'_2$ ). This time stamp is denoted by $ToD(t'_2)$ . The time stamp $ToD(t_2)$ for event $t_2$ is obtained by adjusting the time stamp $ToD(t'_2)$ for event $t'_2$ with an estimate of $\Delta t_2 = ToD(t_2) - ToD(t'_2)$ . The method of adjustment is vendor discretionary. The time stamps $t_3$ and $t_4$ can be obtained in the same way. + +# 9 Physical media specific transmission convergence (PMS-TC) sublayer + +The PMS-TC sublayer resides between the $\alpha/\beta$ interface and $\delta$ interface of the VDSL2 transceiver reference model (see Figure 5-1). It provides transmission medium specific TC functions, such as scrambling, framing, forward error correction (FEC), and interleaving. + +## 9.1 PMS-TC functional model + +The PMS-TC functional models are presented in Figure 9-1 applicable to single latency mode and dual latency mode, and Figure 9-2 applicable to single latency with ROC mode. Up to two bearer channels of transmit user data originated by various TPS-TCs, management data originated by the MPS-TC, and NTR data are incoming via the $\alpha/\beta$ interface in a uniform format, as specified in clause 8.1.2. The incoming user data and the overhead data are multiplexed into one or two latency paths. Each bearer channel is carried over a single latency path (i.e., shall not be split across two latency paths). A Syncbyte is added to each latency path for OH frame alignment. + +Three different modes are allowed: + +- 1) Single latency mode: support of one latency path. The VTU shall support this mode. For this mode, latency path #0 shall be enabled. +- 2) Dual latency mode: support of two latency paths. The VTU may support this mode. For this mode, latency paths #0 and #1 shall be enabled. +- 3) Single latency with ROC mode: support of a single latency path for data with a second overhead-only latency path. The VTU may support this mode. For this mode, the data shall use latency path#1 and the ROC shall use latency path #0. + +NOTE 1 – When transporting two or more applications with different latency and INP requirements and limited higher layer error resilience, a VTU should implement dual latency because, in general, under these conditions dual latency will provide improved performance and/or quality of service. + +The multiplexed data in each latency path (including the overhead-only latency path, if present) is scrambled, encoded using Reed-Solomon forward error correction coding, and interleaved. The interleaved buffers of data of both latency paths are multiplexed into a bit stream to be submitted to the PMD sublayer via the $\delta$ interface. + +All user data bytes incoming via the $\alpha/\beta$ interface are transmitted MSB first (see clause 8.1.2). All serial processing in the PMS-TC (e.g., scrambling, cyclic redundancy check (CRC) calculation) shall be performed LSB first, with the MSB incoming from the $\alpha/\beta$ interface considered as the LSB in the PMS-TC. As a result, the first bit of user data incoming from the $\alpha/\beta$ interface will be the first bit processed by the PMS-TC and the first bit sent towards the PMD sublayer (see clause 9.1.1). + +The management data bytes incoming via the $\alpha/\beta$ interface are transmitted MSB first (see clause 8.1.2). The LSB of the management data incoming from the $\alpha/\beta$ interface shall be considered as the LSB in the PMS-TC, and shall be the first bit processed by the PMS-TC and the first bit sent towards the PMD sublayer (see clause 9.1.1). + +The indicator bits (IB) and NTR bits shall be sent as described in clause 9.5.2.2. + +![Figure 9-1: PMS-TC functional model applicable to single latency mode and dual latency mode. The diagram shows a vertical stack of components. At the top, the α/β interface connects to TPS-TC#0 and TPS-TC#1 (latency path #0) via B00 and B01 signals, and to TPS-TC#0 and TPS-TC#1 (latency path #1) via B10 and B11 signals. Below these are two MUX units. The left MUX receives B00, B01, and a Sync signal, outputting signal A. The right MUX receives B10, B11, and a Sync signal, outputting signal p=1. Between the MUXes is an Overhead block receiving eoc, IB, and NTR signals from the MPS-TC, VME, and 8 kHz sources. Signal A connects to a block containing Scrambler, FEC, and Interleaver, outputting C (L0 bits). Signal p=1 connects to a similar block, outputting L1 bits. Both C and L1 bits are multiplexed by a bottom MUX, which connects to the δ interface and the PMD as (L0+L1) bits. The PMS-TC layer is indicated on the left.](6a7ea9d5162b0a0cfbd8d77c6cac90d1_img.jpg) + +Figure 9-1: PMS-TC functional model applicable to single latency mode and dual latency mode. The diagram shows a vertical stack of components. At the top, the α/β interface connects to TPS-TC#0 and TPS-TC#1 (latency path #0) via B00 and B01 signals, and to TPS-TC#0 and TPS-TC#1 (latency path #1) via B10 and B11 signals. Below these are two MUX units. The left MUX receives B00, B01, and a Sync signal, outputting signal A. The right MUX receives B10, B11, and a Sync signal, outputting signal p=1. Between the MUXes is an Overhead block receiving eoc, IB, and NTR signals from the MPS-TC, VME, and 8 kHz sources. Signal A connects to a block containing Scrambler, FEC, and Interleaver, outputting C (L0 bits). Signal p=1 connects to a similar block, outputting L1 bits. Both C and L1 bits are multiplexed by a bottom MUX, which connects to the δ interface and the PMD as (L0+L1) bits. The PMS-TC layer is indicated on the left. + +G.993.2\_F09-1 + +**Figure 9-1 – PMS-TC functional model applicable to single latency mode and dual latency mode** + +![Figure 9-2: PMS-TC functional model applicable to single latency with ROC mode. This diagram is similar to Figure 9-1 but with a key difference: the TPS-TC#0 and TPS-TC#1 (latency path #0) signals are bypassed above a dashed line representing the α/β interface. The Overhead block (receiving eoc, IB, NTR) and the right-side MUX (receiving B10, B11) are above this interface. Below the interface, the left MUX receives Sync and signals from the Overhead block, outputting A (p=0). The right MUX receives B10, B11, and Sync, outputting p=1. These then pass through Scrambler, FEC, and Interleaver blocks to produce C (L0 bits) and L1 bits, which are multiplexed at the bottom for the δ interface and PMD as (L0+L1) bits.](0f6e3cdce0f01d6ccceabcced508bb5b_img.jpg) + +Figure 9-2: PMS-TC functional model applicable to single latency with ROC mode. This diagram is similar to Figure 9-1 but with a key difference: the TPS-TC#0 and TPS-TC#1 (latency path #0) signals are bypassed above a dashed line representing the α/β interface. The Overhead block (receiving eoc, IB, NTR) and the right-side MUX (receiving B10, B11) are above this interface. Below the interface, the left MUX receives Sync and signals from the Overhead block, outputting A (p=0). The right MUX receives B10, B11, and Sync, outputting p=1. These then pass through Scrambler, FEC, and Interleaver blocks to produce C (L0 bits) and L1 bits, which are multiplexed at the bottom for the δ interface and PMD as (L0+L1) bits. + +G.993.2(15)\_F9-2 + +**Figure 9-2 – PMS-TC functional model applicable to single latency with ROC mode** + +NOTE 2 – The overhead information transmitted on the different latency paths ( $p_0$ , $p_1$ ) may be different depending on the type of OH frame used and the values of framing parameters, as specified in clause 9.5.2. + +Reference points are defined within the block diagram for purposes of clarity only. The reference points are depicted in Figure 9-1 and listed in Table 9-1. + +**Table 9-1 – PMS-TC function internal reference points** + +| Reference point | Definition | +|-------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| A: Mux data frame (MDF) | This reference point is the input of the scrambler of a single latency path. The signal at this reference point is the MDF, and is defined as the grouping of octets from different bearer channels within the same latency path, after the sync overhead data octets have been added. | +| C | This reference point is the output of a single latency path | + +### 9.1.1 $\delta$ interface + +The $\delta_O$ and $\delta_R$ reference points at the VTU-O and VTU-R, respectively, reside between the PMS-TC and the PMD sublayers, as illustrated in Figure 5-2. Both interfaces are functional, are application independent, and are defined by the following signal flows: + +- Data flow; and +- Synchronization flow. + +The $\delta$ interface signals are summarized in Table 9-2. + +**Table 9-2 – $\delta$ interface signal summary** + +| Signal | Description | Direction | +|--------------------------------|----------------------|--------------------------| +| Data signals | | | +| Tx | Transmit data stream | PMS-TC $\rightarrow$ PMD | +| Rx | Receive data stream | PMS-TC $\leftarrow$ PMD | +| Synchronization signals | | | +| Clkp_t | Transmit bit timing | PMS-TC $\leftarrow$ PMD | +| Clkp_r | Receive bit timing | PMS-TC $\leftarrow$ PMD | +| Control signals | | | +| Syncflag | Reconfiguration flag | PMS-TC $\leftarrow$ PMD | + +#### 9.1.1.1 Data flow + +The data flow shall consist of two contra-directional streams of data frames: + +- Transmit data frames (Tx); and +- Receive data frames (Rx). + +The number of bits in each data frame and the number of incoming data frames per second are dependent on the transmission parameters of the PMD sublayer selected during initialization. The bits of the PMS-TC data frame (Figure 9-6) shall be transmitted towards the PMD in sequential order, starting from the first bit of the data frame. + +#### 9.1.1.2 Synchronization flow + +The synchronization flow shall consist of transmit and receive bit-synchronization signals (Clkp\_t, Clkp\_r), both originating from the PMD. + +#### 9.1.1.3 Control flow + +This flow provides a time marker (Syncflag, as specified in Table 9-2) for changes of the PMS-TC parameters during on-line reconfiguration (OLR). The Syncflag is asserted by the PMD and indicates a specific time when the PMS-TC shall start operating with modified parameters. The list of the relevant PMS-TC parameters is for further study. + +## 9.2 Scrambler + +A scrambler shall be used to reduce the likelihood that a long sequence of ZEROS will be transmitted over the channel. The scrambler shall be self-synchronizing such that descrambling can occur without requiring a particular alignment with the scrambled sequence. The scrambling algorithm shall be as represented by the equation below; the output bit of data $x(n)$ at the sample time $n$ shall be: + +$$x(n) = m(n) + x(n - 18) + x(n - 23)$$ + +where $m(n)$ is the input bit of data at the sample time $n$ . All arithmetic shall be modulo 2. + +NOTE – As long as the scrambler is initialized with values other than zero, an "all zeros" sequence for $m(n)$ will result in a pseudo-random sequence of length $2^{23} - 1$ . + +Incoming bytes shall be input to the scrambler LSB first. All data bytes and OH bytes of every multiplex (mux) data frame (see clause 9.5.1) shall be scrambled. + +## 9.3 Forward error correction + +A standard byte-oriented Reed-Solomon code shall be used for forward error correction (FEC). FEC provides protection against random and burst errors. A Reed-Solomon code word shall contain $N_{FEC} = K + R$ bytes, comprised of $R$ check bytes $c_0, c_1, \dots, c_{R-2}, c_{R-1}$ appended to the $K$ data bytes $m_0, m_1, \dots, m_{K-2}, m_{K-1}$ . The check bytes shall be computed from the data bytes using the equation: + +$$C(D) = M(D)D^R \bmod G(D)$$ + +where: + +$$M(D) = m_0 D^{K-1} \oplus m_1 D^{K-2} \oplus \dots \oplus m_{K-2} D \oplus m_{K-1} \text{ is the data polynomial}$$ + +$$C(D) = c_0 D^{R-1} \oplus c_1 D^{R-2} \oplus \dots \oplus c_{R-2} D \oplus c_{R-1} \text{ is the check polynomial}$$ + +$$G(D) = \prod (D \oplus \alpha^i) \text{ is the generator polynomial of the Reed-Solomon code, where the index of the product runs from } i=0 \text{ to } R-1$$ + +The polynomial $C(D)$ is the remainder obtained from dividing $M(D)D^R$ by $G(D)$ . The arithmetic shall be performed in the Galois Field GF(256), where $\alpha$ is a primitive element that satisfies the primitive binary polynomial $x^8 \oplus x^4 \oplus x^3 \oplus x^2 \oplus 1$ . A data byte $(d_7, d_6, \dots, d_1, d_0)$ is identified with the Galois Field element $d_7 \alpha^7 \oplus d_6 \alpha^6 \oplus \dots \oplus d_1 \alpha \oplus d_0$ . + +Both $K$ and $R$ shall be programmable parameters. Valid values for the number of check bytes $R$ in the codeword are 0, 2, 4, 6, 8, ..., 16. Valid values for the number of bytes in the codeword $N_{FEC}$ (codeword size) are all integers from 32 to 255, inclusive. A VTU shall support all valid values of $R$ and $N_{FEC}$ . + +The FEC for the ROC shall only use $R=16$ and $N_{FEC}$ values from 32 to 66 with $q = 1$ . + +## 9.4 Interleaving + +Interleaving shall be provided in all supported latency paths to protect the data against bursts of errors by spreading the errors over a number of Reed-Solomon codewords. The convolutional interleaver adopted for VDSL2 shall follow the rule: + +- $I$ is the interleaver block size in bytes. Each of the $I$ bytes in an interleaver block $B_0 B_1 \dots B_{I-1}$ shall be delayed by the interleaver by an amount that varies linearly with the byte index. More precisely byte $B_j$ (with index $j$ ) shall be delayed by $\Delta[j] = (D - 1) \times j$ bytes, where $D$ is the interleaver depth in bytes, and $D$ and $I$ are co-prime (have no common divisor except for 1). + +For any interleaver input of size $D \times I$ bytes, the relationship between the index of each input byte ( $n_{in}$ ) and the index of each output byte ( $n_{out}$ ) is given by $n_{out} = (n_{in} + \Delta[j])$ , where $j = n_{in} \bmod I$ and $\Delta[j] = (D - 1) \times j$ . + +The total delay of the interleaver/de-interleaver combination is $(D - 1) \times (I - 1)$ bytes. + +The RS codeword length $N_{FEC}$ shall be an integer multiple of $I$ , i.e., $N_{FEC} = q \times I$ , where $q$ is an integer between 1 and 8 inclusive. All values of $q$ shall be supported. Codewords shall be mapped to interleaver blocks such that the first $I$ bytes of the codeword map to the $I$ bytes $B_0 B_1 \dots B_{I-1}$ of the first interleaver block. + +The interleaver depth shall be set to meet the requirements for error-burst protection and latency. The VTU shall support all integer values of $D$ from 1 to $D_{max}$ , as specified for the particular profile (see Table 6-1). At any data rate, the minimum latency occurs when the interleaver is turned off. If both latency paths are supported, interleaving shall be supported on both latency paths. The same valid and mandatory configuration parameters shall apply to all supported latency paths. + +The interleaving for the ROC shall only use $D$ values up to 20. + +A summary of interleaver parameters is given in Table 9-3. + +**Table 9-3 – Summary of interleaver parameters** + +| Parameter(s) | Value for: | Value for: | +|-----------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------| +| |
  • • single latency mode (latency path #0)
  • • dual latency mode (latency paths #0 and #1)
  • • single latency with ROC mode (latency path #1)
| single latency with ROC mode (latency path #0) | +| $D$ and $I$ | Co-prime | Co-prime | +| $q$ | Integer between 1 and 8, inclusive | 1 | +| $N_{FEC}$ | Integer between 32 and 255 inclusive,
$N_{FEC} = q \times I$ | Integer between 32 and 66 inclusive,
$N_{FEC} = q \times I$ | +| Total delay of the interleaver/de-interleaver combination | $(D-1) \times (I-1)$ bytes | $(D-1) \times (I-1)$ bytes | + +### 9.4.1 Dynamic change of interleaver depth + +A method to dynamically change the interleaver depth during transmission is defined for VDSL2. This method is optional. Support shall be indicated during initialization in O-MSG 1 and R-MSG 2. + +NOTE – Although this clause defines the procedure for dynamically changing the interleaver depth during transmission, the control command for initiating this procedure is not defined in this version of in this Recommendation. The calling procedure for dynamic change of interleaver depth will be defined in a future revision to this Recommendation. + +A change of the interleaver depth shall only be initiated at the first byte of an RS codeword, where $k$ is the sequence number of this byte at the input of the interleaver. + +For an increase of the interleaver depth from $D_{old}$ to $D_{new}$ with $D_{old} < D_{new}$ the interleaver output is defined by: + +$$y(n + \Delta_{old}[j]) = x(n); \text{ for } n + \Delta_{old}(j) < k, \text{ where } \Delta_{old}[j] = (D_{old} - 1) \times j$$ + +$$y(n + \Delta_{new}[j]) = x(n); \text{ for } n + \Delta_{old}(j) \geq k, \text{ where } \Delta_{new}[j] = (D_{new} - 1) \times j$$ + +For a decrease of the interleaver depth from $D_{old}$ to $D_{new}$ with $D_{old} > D_{new}$ the interleaver output is defined by: + +$$y(n + \Delta_{old}[j]) = x(n); \text{ for } n + \Delta_{new}(j) + \delta < k$$ + +$$y(n + \Delta_{new}[j] + \delta) = x(n); \text{ for } n + \Delta_{new}(j) + \delta \geq k$$ + +where $\delta$ is the length of the transition and is given by: + +$$\delta = \lceil (D_{old} - D_{new}) \cdot (I - 1) / I \rceil \cdot I$$ + +$\delta$ is not a persistent delay; it can be compensated by interrupting the interleaver input by the time represented by $\delta$ bytes. + +The values of bytes that are not defined by the rules above are unspecified. + +If a change of the interleaver depth is to be accompanied by a corresponding change of the data rate in the particular latency path (e.g., SRA – see clause 13.1), the change of $D$ shall be coordinated with the corresponding change of parameter $L_p$ (see Table 9-8) as described in clause 13.3. + +Dynamic change of interleaver depth shall not be used for the ROC. + +## 9.5 Framing + +The framing format of a single latency path is summarized in Figures 9-2 and 9-3. Both latency paths have the same framing format, but their framing parameters (specified in Table 9-8) are independent. Index $p$ indicates the latency path and may take values 0 and 1. + +### 9.5.1 Mux data frame (MDF) and RS codewords + +The overhead channel and the first and second bearer channels are multiplexed into the mux data frames (MDF). The format of the MDF is presented in Figure 9-3. To form the MDF, the PMS-TC pulls out sequentially $O_{pi}$ octets from the overhead (OH) buffer and then $B_{p0}$ and $B_{p1}$ octets from the first and the second bearer channel buffers, respectively. + +![Figure 9-3 – MDF and RS codeword structure. The diagram shows four levels of data structure mapping. Level 1: A Mux data frame (MDF) with a total size of Ceil(G_p/T_p) + B_p0 + B_p1 octets, containing Overhead (O_pi octets), Bearer channel 0 (B_p0 or B_p0 + 1 octets), and Bearer channel 1 (B_p1 octets). Level 2: A sequence of MDFs (#1, ..., #i, ..., #M_p) followed by FEC (R_p octets), forming an RS codeword RS(N_FEC_p + N_FEC_p - R_p) = N_FEC_p octets. Level 3: A sequence of RS codewords (#1, ..., #n, ..., #T_p/M_p), with a total size of (T_p/M_p) RS codewords = N_FEC_p * (T_p/M_p) octets, including the G_p OH octets of one OH sub-frame. Level 4: A sequence of T_p/M_p RS codewords (#1, ..., #m, ..., #U_p), with a total size of U_p * (T_p/M_p) RS codewords = PERB_p octets, including the U_p * G_p = SEQ_p OH octets of one OH frame.](8c3eb53c927f55acd19723cfcd0c43b6_img.jpg) + +Mux data frame (MDF) + +$\text{Ceil}(G_p/T_p) + B_{p0} + B_{p1}$ octets + +Overhead $O_{pi}$ octets + +Bearer channel 0 $B_{p0}$ or $B_{p0} + 1$ octets + +Bearer channel 1 $B_{p1}$ octets + +MDF #1 + +... + +MDF #i + +... + +MDF # $M_p$ + +FEC ( $R_p$ octets) + +RS codeword RS( $N_{FEC_p} + N_{FEC_p} - R_p$ ) = $N_{FEC_p}$ octets + +RS codeword #1 + +... + +RS codeword # $n$ + +... + +RS codeword # $T_p/M_p$ + +$(T_p/M_p)$ RS codewords = $N_{FEC_p} \times (T_p/M_p)$ octets +(including the $G_p$ OH octets of one OH sub-frame) + +$T_p/M_p$ RS codeword (#1) + +... + +$T_p/M_p$ RS codeword s (# $m$ ) + +... + +$T_p/M_p$ RS codeword s (# $U_p$ ) + +$U_p \times (T_p/M_p)$ RS codewords = $PERB_p$ octets +(including the $U_p \times G_p = SEQ_p$ OH octets of one OH frame) + +G.993.2(15)\_F9-3 + +Figure 9-3 – MDF and RS codeword structure. The diagram shows four levels of data structure mapping. Level 1: A Mux data frame (MDF) with a total size of Ceil(G\_p/T\_p) + B\_p0 + B\_p1 octets, containing Overhead (O\_pi octets), Bearer channel 0 (B\_p0 or B\_p0 + 1 octets), and Bearer channel 1 (B\_p1 octets). Level 2: A sequence of MDFs (#1, ..., #i, ..., #M\_p) followed by FEC (R\_p octets), forming an RS codeword RS(N\_FEC\_p + N\_FEC\_p - R\_p) = N\_FEC\_p octets. Level 3: A sequence of RS codewords (#1, ..., #n, ..., #T\_p/M\_p), with a total size of (T\_p/M\_p) RS codewords = N\_FEC\_p \* (T\_p/M\_p) octets, including the G\_p OH octets of one OH sub-frame. Level 4: A sequence of T\_p/M\_p RS codewords (#1, ..., #m, ..., #U\_p), with a total size of U\_p \* (T\_p/M\_p) RS codewords = PERB\_p octets, including the U\_p \* G\_p = SEQ\_p OH octets of one OH frame. + +**Figure 9-3 – MDF and RS codeword structure** + +MDFs are mapped to an RS codeword as presented in Figure 9-3. Each RS codeword includes the same integer number, $M_p$ , of MDFs and the same number of redundancy octets $R_p$ ; the first octet of each codeword is the first octet of the first MDF of this codeword. The total size of the RS codeword is $N_{FEC_p}$ bytes. All octets in the bearer channel fields of the MDF shall be mapped to transmit LSB first. The bits of the overhead octets shall be mapped as specified in clause 9.5.2.2. + +The number $O_{pi}$ of overhead octets per MDF shall be as specified in clause 9.5.2.1. Because of the way overhead octets are assigned to MDFs, the number of overhead octets in an MDF can vary by up to one octet. Those MDFs with one fewer overhead octets shall instead carry one additional octet from bearer channel #0 so that the total number of octets in all MDFs is the same. + +NOTE – The ratio of the bit rates of two bearer channels may not exactly fit the real ratio of the transmitted bit rates. The setting of the bit rate ratio has a finer granularity for larger MDFs. + +### 9.5.2 Overhead (OH) frame, subframe and superframe + +The OH frame carries the OH data and framing synchronization. The OH frame consists of an integer number $U_p$ of OH subframes, as shown in Figure 9-4. All OH subframes have the same format. The total length of the OH frame (the OH frame period) is $PERB_p$ octets. The OH frame parameters $U_p$ and $PERB_p$ are specified in Table 9-8. + +![Diagram illustrating the overhead subframe, frame, and superframe structure. The top level shows T_p Mux data frames (carried in T_p/M_p RS codewords) divided into MDF #1, MDF #2, MDF #3, ..., MDF #T_p. Below this, the OH octets are distributed: O_p1 OH octets, O_p2 OH octets, O_p3 OH octets, ..., O_pT_p OH octets. These are grouped into OH sub-frames: OH sub-frame #1 (G_p OH octets), ..., OH sub-frame #n (G_p OH octets), ..., OH sub-frame #U_p (G_p OH octets). The total OH octets for a subframe is G_p. An OH-frame consists of U_p OH sub-frames, totaling (U_p x G_p SEQ_p octets). Finally, OH frames are grouped into OH superframes: OH frame #1 (SEQ_p OH octets), ..., OH frame #m (SEQ_p OH octets), ..., OH frame #F_p (SEQ_p OH octets). The total OH superframe size is (F_p x SEQ_p OH octets). A note indicates that OH frame #1 has a different Syncbyte value. A formula shows the sum of OH octets: O_p1 + O_p2 + O_p3 + ... + O_pT_p = G_p. The diagram is labeled G.993.2(15)_F9-4.](e2dad48ec062e71202459a9ab82261e4_img.jpg) + +Diagram illustrating the overhead subframe, frame, and superframe structure. The top level shows T\_p Mux data frames (carried in T\_p/M\_p RS codewords) divided into MDF #1, MDF #2, MDF #3, ..., MDF #T\_p. Below this, the OH octets are distributed: O\_p1 OH octets, O\_p2 OH octets, O\_p3 OH octets, ..., O\_pT\_p OH octets. These are grouped into OH sub-frames: OH sub-frame #1 (G\_p OH octets), ..., OH sub-frame #n (G\_p OH octets), ..., OH sub-frame #U\_p (G\_p OH octets). The total OH octets for a subframe is G\_p. An OH-frame consists of U\_p OH sub-frames, totaling (U\_p x G\_p SEQ\_p octets). Finally, OH frames are grouped into OH superframes: OH frame #1 (SEQ\_p OH octets), ..., OH frame #m (SEQ\_p OH octets), ..., OH frame #F\_p (SEQ\_p OH octets). The total OH superframe size is (F\_p x SEQ\_p OH octets). A note indicates that OH frame #1 has a different Syncbyte value. A formula shows the sum of OH octets: O\_p1 + O\_p2 + O\_p3 + ... + O\_pT\_p = G\_p. The diagram is labeled G.993.2(15)\_F9-4. + +G.993.2(15)\_F9-4 + +**Figure 9-4 – Overhead subframe, frame, and superframe structure** + +An OH superframe is composed of $F_p$ OH frames. + +#### 9.5.2.1 OH subframe format + +The OH subframe spans $T_p$ MDFs and includes $G_p$ OH octets distributed among these MDFs. The number of OH octets, $O_{pi}$ , in MDF # $i$ of the OH subframe shall be: + +$$O_{pi} = \begin{cases} \left\lceil \frac{G_p}{T_p} \right\rceil & \text{for } i \leq G_p - T_p \times \left\lceil \frac{G_p}{T_p} \right\rceil, \\ \left\lceil \frac{G_p}{T_p} \right\rceil & \text{otherwise} \end{cases}, \quad i = 1, 2, \dots, T_p; \quad 0 \leq O_{pi} \leq 8.$$ + +Settings for $G_p$ and $T_p$ shall comply with the following rules: + +Rule 1: $M_p/S_p \leq 64$ ; + +$$\text{Rule 2: } \left\lceil \frac{G_p}{T_p} \right\rceil \times \left\lceil \frac{M_p}{S_p} \right\rceil + \left[ \frac{\left\lceil \frac{M_p}{S_p} \right\rceil}{T_p} \right] \times (G_p \bmod T_p) + \min \left( \left\lceil \frac{M_p}{S_p} \right\rceil \bmod T_p, G_p \bmod T_p \right) \leq 8$$ + +The valid range of the number of OH octets in MDF $O_{pi}$ is from 0 to 8; the valid range of the number of OH octets in the OH subframe $G_p$ is from 1 to 32. + +The OH subframe shall span an integer number of RS codewords: $T_p = k \times M_p$ , where $k$ is an integer. + +NOTE 1 – The average number of OH octets per MDF is equal to $G_p/T_p$ and can be a non-integer. + +NOTE 2 – Since the OH frame spans an integer number of RS codewords and an integer number of MDFs, the boundaries of the OH frame, the RS codeword, and the MDF are aligned. + +#### 9.5.2.2 Mapping of the OH data + +The mapping of the OH data to the OH frame shall be as presented in Table 9-4. Two types of OH frames shall be supported: + +Type 1 – Full frame; + +Type 2 – Auxiliary frame. + +For single latency, the latency path shall use OH frame Type 1. For Dual Latency, one latency path shall use OH frame Type 1 and the other shall use OH frame Type 2. For single latency with ROC, the ROC (in latency path 0) shall use OH frame Type 1 and latency path 1 shall use OH frame Type 2. The latency path selected for OH frames of Type 1 shall be indicated during initialization by the parameter value in the MSGLP field (see clauses 12.3.5.2.1.3 and 12.3.5.2.2.3). When the ROC is used, MSGLP (see Tables 12-56 and 12-60) shall have the value 0. + +**Table 9-4 – Contents of Type 1 and Type 2 OH frames** + +| OH frame Type 1 | | | +|------------------------|----------------------------------|---------------------------------------------------------------------------------------------------------------------------------| +| Octet number | OH field | Description | +| 1 | CRC p | CRC (clause 9.5.2.3) | +| 2 | Syncbyte | Syncbyte = AC 16 when the OH frame indicates the start of an OH superframe, otherwise
Syncbyte = 3C 16 | +| 3 | IB-1 | PMD-related primitives (Note 1, Table 9-5) | +| 4 | IB-2 | PMS-TC-related primitives (Note 1, Table 9-5) | +| 5 | IB-3 | TPS-TC-related and system-related primitives (Note 1, Table 9-5) | +| 6 | NTR | Network timing reference (Note 2, clause 8.3) | +| >6 | MSG | Message overhead (Note 3, clause 11.2) | +| OH frame Type 2 | | | +| 1 | CRC p | CRC (clause 9.5.2.3) | +| 2 | Syncbyte | Syncbyte = AC 16 when the OH frame indicates the start of an OH superframe, otherwise
Syncbyte = 3C 16 | +| 3 | Reserved for allocation by ITU-T | The value for the reserved field shall be FF 16 | +| >3 | Reserved for allocation by ITU-T | The value for the reserved field shall be FF 16 (Note 4) | + +**Table 9-4 – Contents of Type 1 and Type 2 OH frames** + +| OH frame Type 1 | | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|-------------| +| Octet number | OH field | Description | +| NOTE 1 – The IB (indicator bits) inform the far end of anomalies and defects; valid in both directions for OH frames of Type 1. IB that are not used shall be set to ONE.
NOTE 2 – The NTR provides an 8 kHz timing reference for the CPE; valid only in the downstream direction for OH frames of Type 1. If the VTU-O indicates that it will not transport NTR, the NTR field shall also be set to FF 16 . In the upstream direction, the NTR field shall always be set to FF 16 .
NOTE 3 – The MSG field transports eoc messages; valid in both directions only for OH frames of Type 1.
NOTE 4 – If the "flexible OH frame Type 2" is not supported (see clauses 12.3.5.2.1.1 (O-MSG1) and clause 12.3.5.2.2.1 (R-MSG2)), the number of additional reserved octets shall be equal to 5, i.e., the OH frame Type 2 shall contain 8 octets. If the "flexible OH frame Type 2" is supported, the number of additional octets is determined by the selected framing parameters. | | | + +Mapping of the CRC, IB and NTR bits to the OH frame fields shall be as specified in Table 9-5; the LSB shall be transmitted first. Mapping of the MSG bytes into the OH frame shall be LSB first, as specified in clauses 8.2.3 and 9.1. + +**Table 9-5 – OH bit mapping** + +| OH field | D7 (MSB) | D6 | D5 | D4 | D3 | D2 | D1 | D0 (LSB) | Defined in | +|----------|------------------------|------------------------|------------------------|------------------------|------------------------|------------------------|------------------------|------------------------|-----------------| +| CRC | crc7 | crc6 | crc5 | crc4 | crc3 | crc2 | crc1 | crc0 | 9.5.2.3 | +| IB-1 | los | rdi | lpr | 1 | 1 | 1 | 1 | 1 | 11.2.4, 11.3 | +| IB-2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | +| IB-3 | TIB#0-0 | TIB#0-1 | TIB#0-2 | TIB#0-3 | TIB#1-0 | TIB#1-1 | TIB#1-2 | TIB#1-3 | 11.2.4, Annex L | +| NTR | ntr7 | ntr6 | ntr5 | ntr4 | ntr3 | ntr2 | ntr1 | ntr0 | 8.3 | + +##### 9.5.2.2.1 Communication of ToD Frequency Synchronization Data via OH frame Type 1 + +Table 9-6 shows the modified OH frame Type1 structure for passing the ToD frequency synchronization data (i.e., ToD phase difference and corresponding $t_1$ event number) from the VTU-O to the VTU-R. Octet number 7, the ToD\_FSync octet, is inserted after the NTR octet prior to the MSG field. The ToD frequency synchronization data is sent in a ToD\_FSync Frame that contains three octets: one octet contains the 6 bits of the $t_1$ event number, and two octets identifying the 16-bit ToD phase difference value. One octet of the ToD\_FSync Frame is transmitted in each OH frame, so the ToD\_FSync Frame spans three OH frame periods ( $PER_p$ ). Table 9-7 defines the frame format structure of the ToD\_FSync Frame. Special values for the Syncbyte are used to identify the beginning of the ToD\_FSync Frame. + +The VTU-O shall insert the ToD frequency synchronization data in the OH frame once per super-frame for each $t_1$ event. The value of $PER_p \leq 20$ ms. Therefore, the ToD\_FSync frame spans less than a super-frame period, and occasionally a ToD phase difference and corresponding $t_1$ event number may need to be transmitted twice. + +The ToD Frequency Synchronization data should be sent in the first available OH frame immediately following the $t_1$ event. + +The value of the capacity of the MSG channel is reduced by one octet, so the message overhead data rate for the updated OH frame Type 1 is $msg_p = OR_p \times (SEQ_p - 7) / SEQ_p$ and the upper lower $msg_p$ + +rates are scaled accordingly (see the $msg_p$ entry in Table 9-8). The above frame structure shall be used if and only if during initialization the time synchronization is enabled and the OH frame is selected for the transport of the ToD phase difference values. + +**Table 9-6 – Modified OH frame Type 1 with ToD frequency synchronization frame extension** + +| OH frame Type 1 | | | +|-----------------|------------------|------------------------------------------------------------------| +| Octet number | OH field | Description | +| 1 | CRC p | CRC (clause 9.5.2.3) | +| 2 | Syncbyte | Values for the Syncbyte are defined in Figure 9-5 | +| 3 | IB-1 | PMD-related primitives (Note 1, Table 9-4) | +| 4 | IB-2 | PMS-TC-related primitives (Note 1, Table 9-4) | +| 5 | IB-3 | TPS-TC-related and system-related primitives (Note 1, Table 9-4) | +| 6 | NTR | Network timing reference (Note 2, clause 8.3) | +| 7 | ToD_FSync | One Byte of ToD FSync Frame (Table 9-7) | +| > 7 | MSG | Message overhead (Note 3, clause 11.2) | + +**Table 9-7 – ToD\_FSync frame structure** + +| Octet number | OH field | Description | +|--------------|--------------------------------------------------------------------------------------------------|----------------------------------------------| +| 1 | [0 0 c 5 c 4 c 3 c 2 c 1 c 0 ] | $t_1$ event number | +| 2 | [b 7 ... b 2 b 1 b 0 ] | Lower byte of the ToD phase difference value | +| 3 | [b 15 ... b 10 b 9 b 8 ] | Higher byte of the ToD phase difference | + +![Timing diagram showing the sequence of OH frames, ToD_FSync events, and OH Superframes. The diagram shows a sequence of 9 OH Frames. Above the first frame is AC16 (OH frame start). Above the second frame is 3316 (Common ToD_FSync and OH Superframe start). Above the third frame is AC16. Above the fourth frame is AC16. Above the fifth frame is A316 (ToD_FSync start). Above the sixth frame is AC16. Above the seventh frame is 3C16 (Syncbyte = OH Superframe start). Above the eighth frame is 8C16. Above the ninth frame is AC16. Below the OH frames, the ToD_FSync events are shown as four blocks. Below the ToD_FSync events, the OH Superframes are shown as two blocks.](cf018d13814389b0bd7f94a2f9bb812a_img.jpg) + +Timing diagram showing the sequence of OH frames, ToD\_FSync events, and OH Superframes. The diagram shows a sequence of 9 OH Frames. Above the first frame is AC16 (OH frame start). Above the second frame is 3316 (Common ToD\_FSync and OH Superframe start). Above the third frame is AC16. Above the fourth frame is AC16. Above the fifth frame is A316 (ToD\_FSync start). Above the sixth frame is AC16. Above the seventh frame is 3C16 (Syncbyte = OH Superframe start). Above the eighth frame is 8C16. Above the ninth frame is AC16. Below the OH frames, the ToD\_FSync events are shown as four blocks. Below the ToD\_FSync events, the OH Superframes are shown as two blocks. + +Key + +AC16 = OH frame start + +3C16 = Syncbyte = OH Superframe start + +A316 = ToD\_FSync start + +3316 = Common ToD\_FSync and OH Superframe start + +G.993.2(15)\_F9-5 + +**Figure 9-5 – Definition of OH sync byte values** + +#### 9.5.2.3 Cyclic redundancy check (CRC) + +A one-byte CRC shall be computed for each OH frame period of each latency path separately. For a $t$ -bit data message transmitted during the OH frame period, the CRC shall be computed using the following equation: + +$$crc(D) = M(D) \times D^8 \text{ modulo } G(D)$$ + +where: + +$$\begin{aligned} M(D) &= m_0 D^{t-1} + m_1 D^{t-2} + \dots + m_{t-2} D + m_{t-1} \text{ is the data message polynomial,} \\ G(D) &= D^8 + D^4 + D^3 + D^2 + 1 \text{ is the generating polynomial,} \\ \text{crc}(D) &= \text{crc}_0 D^7 + \text{crc}_1 D^6 + \dots + \text{crc}_6 D + \text{crc}_7 \text{ is the CRC polynomial, and} \\ D &\text{ is the delay operator.} \end{aligned}$$ + +That is, $\text{crc}(D)$ shall be the remainder when $M(D) \times D^8$ is divided by $G(D)$ . Each octet of the data message shall be input into the $\text{crc}(D)$ equation LSB first. + +The values of $\text{crc}_0$ to $\text{crc}_7$ are the CRC bits to be carried in the next OH frame as specified in clause 9.5.2.2 so that the LSB ( $\text{crc}_0$ ) is transmitted first. The CRC bits of the first OH frame (at the entrance into showtime) shall be set to ZERO. + +The CRC shall be computed prior to scrambling for each subsequent period of time equal to the duration of the OH frame in bytes ( $\text{PERB}_p$ ). The data message covered by the CRC shall include all bits of all MDFs transmitted during the period of the OH frame, except the CRC byte. The first CRC shall be computed over the data message that includes the first OH frame period (after the entrance into showtime); the second CRC shall be computed over the data message that includes the second OH frame period; and so on. + +#### 9.5.2.4 OH superframe + +The OH superframe contains $F_p$ OH frames and is intended to provide an additional timing reference. The value of $F_p$ shall be selected so that the duration of the OH superframe is significantly longer than the time required to exchange management information between the VTU-O and the VTU-R. The first octet of the OH superframe coincides with the first octet of the OH frame and shall be marked by Syncbyte = AC16. The valid range of $F_p$ is from 1 to 255. + +### 9.5.3 Multiplexing of data from two latency paths + +#### 9.5.3.1 Robust overhead channel (ROC) + +As defined in clause 9.5.2.2, all overhead traffic is mapped into one of the latency paths. Optionally, the VTUs may negotiate a robust overhead channel (ROC) (see clause 9.1). The ROC is effectively a latency path that carries only overhead data. When the ROC is enabled (single latency with ROC mode), all overhead data (see clause 11.2.3.3) shall be sent through latency path #0. In this mode, latency path #0 is also referred to as the ROC. + +#### 9.5.3.2 Multiplexing + +The assigned number of bits, $L_0$ and $L_1$ , from the RS codewords of latency paths #0 and #1, respectively, shall be mapped to the data frame as shown in Figure 9-6. The bits shall be extracted from the octets of the RS codewords in sequential order, LSB first. The first bit of each extracted group of $L_0$ bits shall be the first bit of the data frame. When the VTU operates in single latency with ROC mode (see clause 9.1), $L_0$ shall be an integer number of bytes consisting of overhead data only. + +When single latency with ROC mode is enabled, the $L_0$ bits shall not share the same subcarriers with $L_1$ bits. + +![Diagram showing the multiplexing of two latency paths (p=0 and p=1) into data frames. Two buffers, 'Buffer of path p=0' and 'Buffer of path p=1', are shown at the top. Arrows from each buffer point to alternating bit segments within a sequence of data frames. The sequence shows segments labeled L0 bits and L1 bits. Below the segments, labels indicate 'Data frame k-1', 'Data frame k', and 'Data frame k+1'. The diagram illustrates that bits from both paths are interleaved within each data frame. A small label 'G.993.2(15)_F9-6' is in the bottom right corner.](e404de9a69c05473fbd6af28ee32311b_img.jpg) + +Diagram showing the multiplexing of two latency paths (p=0 and p=1) into data frames. Two buffers, 'Buffer of path p=0' and 'Buffer of path p=1', are shown at the top. Arrows from each buffer point to alternating bit segments within a sequence of data frames. The sequence shows segments labeled L0 bits and L1 bits. Below the segments, labels indicate 'Data frame k-1', 'Data frame k', and 'Data frame k+1'. The diagram illustrates that bits from both paths are interleaved within each data frame. A small label 'G.993.2(15)\_F9-6' is in the bottom right corner. + +**Figure 9-6 – Multiplexing of two latency paths into data frames carried by DMT symbols** + +### 9.5.4 Framing parameters + +Framing parameters for latency path $p$ are specified in Table 9-8. Two groups of parameters are specified: + +- Primary framing parameters; and +- Derived framing parameters. + +Primary framing parameters are those communicated to the other VTU during initialization for frame setup (see clause 12.3.5). Derived framing parameters are computed by the VTU using the primary framing parameters to establish the complete frame setting and parameters intended for verification of the data channel and overhead channel bit rates and provide other important characteristics of the PMS-TC when specific framing parameters are set. + +**Table 9-8 – Framing parameters for latency path $p$** + +| Parameter | Definition | +|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Primary framing parameters | | +| $B_{pn}$ | The number of octets from bearer channel # $n$ per MDF. The range of values is from 0 to 254. When $G_p/T_p$ is not an integer, the number of octets from the bearer channel #0 varies between $B_{p0}$ and $B_{p0} + 1$ . | +| $R_p$ | The number of redundancy octets in the RS codeword. | +| $M_p$ | The number of MDFs in an RS codeword. Only values of 1, 2, 4, 8 and 16 shall be supported. | +| $T_p$ | The number of MDFs in an OH subframe; $T_p = k \times M_p$ , where $k$ is an integer. The value of $T_p$ shall not exceed 64. | +| $G_p$ | The total number of overhead octets in an OH subframe; $1 \leq G_p \leq 32$ . | +| $F_p$ | Number of OH frames in the OH superframe. $1 \leq F_p \leq 255$ . | +| $L_p$ | The number of bits from latency path $p$ transmitted in each data symbol. | +| Derived framing parameters | | +| $N_{FECp}$ | The RS codeword size:
$N_{FECp} = M_p \times \left[ \text{ceiling} \left( \frac{G_p}{T_p} \right) + B_{p0} + B_{p1} \right] + R_p \text{ bytes}$ | + +**Table 9-8 – Framing parameters for latency path $p$** + +| Parameter | Definition | +|------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $O_{pi}$ |
  • The number of overhead octets in the i^{\text{th}} MDF of the OH subframe:
  • O_{pi} = \begin{cases} \left\lceil \frac{G_p}{T_p} \right\rceil & \text{for } i \leq G_p - T_p \times \left\lceil \frac{G_p}{T_p} \right\rceil \\ \left\lceil \frac{G_p}{T_p} \right\rceil & \text{otherwise} \end{cases}, i = 1, 2, \dots, T_p; 0 \leq O_{pi} \leq 8.
| +| $PERB_p$ |

The number of bytes in the overhead frame:

$PERB_p = \frac{T_p \times N_{FECp}}{M_p} \times \left\lceil \frac{\hat{Q} \times M_p}{T_p \times N_{FECp}} \right\rceil \text{ bytes}$

where:

$\hat{Q} = \begin{cases} Q & \text{if } TDR_p \geq TDR_0 \\ Q \cdot \frac{TDR_p}{TDR_0} & \text{if } TDR_p < TDR_0 \end{cases}$

and where:

TDR_p is the total data rate of latency path p in kbit/s,
Q = 17\,000 bytes,
TDR_0 = 7\,880 kbit/s.

| +| $TDR_p$ |

The total data rate of latency path p (at reference point C):

$TDR_p = L_p \times f_s \text{ kbit/s},$

where f_s is the data symbol rate in ksymbols/s (see clause 10.4.4).

| +| $S_p$ |

The number of data symbols over which the RS codeword spans,

$S_p = \frac{8 \times N_{FECp}}{L_p}$

The value of S_p may be a non-integer, and shall not exceed 64.

| +| $NDR_{pn}$ |

The net data rate for bearer channel #0:

$NDR_{p0} = \left[ B_{p0} + \text{ceiling} \left( \frac{G_p}{T_p} \right) - \frac{G_p}{T_p} \right] \times \frac{8 \times M_p \times f_s}{S_p} \text{ kbit/s}.$

The net data rate for bearer channel #1:

$NDR_{p1} = B_{p1} \times \frac{8 \times M_p \times f_s}{S_p} \text{ kbit/s}.$

The settings of framing parameters shall provide net\_min_n < NDR_{pn} < net\_max_n for all defined bearer channels over relevant latency paths.

| +| $NDR_p$ |

The net data rate for latency path p:

$NDR_p = L_p \times f_s \times \frac{K_p}{N_{FECp}} - OR_p = \left( K_p - \frac{G_p \times M_p}{T_p} \right) \times \frac{8 \times f_s}{S_p} \text{ kbit/s}.$

where K_p = N_{FECp} - R_p.

| + +**Table 9-8 – Framing parameters for latency path *p*** + +| Parameter | Definition | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $U_p$ | The number of OH subframes in the OH frame:
$U_p = \frac{PERB_p}{N_{FECp}} \times \frac{M_p}{T_p}$ | +| $SEQ_p$ | The number of overhead bytes in the OH frame:
$SEQ_p = U_p \times G_p \text{ bytes.}$ | +| $OR_p$ | The overhead data rate for latency path p :
$OR_p = \frac{G_p \times M_p}{S_p \times T_p} \times 8 \times f_s \text{ kbit/s.}$ | +| $msg_p$ | The message overhead data rate (for OH frame Type 1 only, excluding the ToD_FSync octet – see Table 9-6):
$msg_p = OR_p \times \frac{SEQ_p - 6}{SEQ_p} \text{ kbit/s.}$

The settings of framing parameters shall provide msg_{\min} < msg_p < msg_{\max}.
The settings for msg_{\min} and msg_{\max} shall comply with the following conditions:
16 \text{ kbit/s} \leq msg_{\min} \leq 236 \text{ kbit/s}; msg_{\max} = 256 \text{ kbit/s}.
The message overhead data rate (for OH frame Type 1 including the ToD_FSync octet – see Table 9-6):
msg_p = OR_p \times (SEQ_p - 7) / SEQ_p \text{ kbit/s.}

| +| $PER_p$ | The duration of the overhead frame in ms (Note):
$PER_p = \frac{T_p \times S_p \times U_p}{f_s \times M_p} = \frac{8 \times PERB_p}{L_p \times f_s} \text{ ms.}$ | +| NOTE – In clauses 7.2.1.1.3 and 7.2.1.2.3 of [ITU-T G.997.1], a one-second counter is used to declare a near-end severely errored second (SES). The one-second counter shall be incremented by the $\Delta CRCsec_p$ (the one-second normalized CRC anomaly counter increment) for each occurrence of a crc-p anomaly. A $\Delta CRCsec_p$ value is defined for each downstream and upstream latency path separately, as a real value in the 0.125 to 8 range, as: | | +| $\Delta CRCsec_p = \begin{cases} 1 & \text{if } 15 \leq PER_p \leq 20 \\ \frac{PER_p}{15} & \text{if } PER_p < 15 \end{cases}$ | | + +### 9.5.5 Parameter 1/*S* + +Parameter 1/*S* defines the total number of Reed-Solomon codewords decoded within a single data symbol. It is equal to: + +$$1/S = \sum_p \text{ceiling} \left( \frac{1}{S_p} \right)$$ + +where $S_p$ is the number of data symbols over which the RS codeword of latency path *p* spans, and the sum is over all enabled latency paths. The value of $S_p$ may be non-integer, and shall be computed as specified in Table 9-8. + +The range of 1/*S* values ( $1/64 \leq 1/S \leq (1/S)_{\max}$ ) is profile dependent. The mandatory values of $(1/S)_{\max}$ + +for different profiles are defined in Table 6-1. Optional extended (valid) values of $(1/S)_{max}$ for different profiles are specified in Table 9-9. + +**Table 9-9 – Optional extended values of $(1/S)_{max}$** + +| Parameter | Parameter value for profile | | | | | | | | +|--------------------------|-----------------------------|----|----|----|-----|-----|-----|-----| +| | 8a | 8b | 8c | 8d | 12a | 12b | 17a | 30a | +| $(1/S)_{max}$ downstream | 64 | 64 | 64 | 64 | 64 | 64 | 64 | 32 | +| $(1/S)_{max}$ upstream | 32 | 32 | 32 | 32 | 64 | 64 | 64 | 32 | + +## 9.6 Impulse noise protection ( $INP_p$ ) + +$INP_p$ (impulse noise protection for latency path $p$ ) is defined as the number of consecutive DMT symbols or fractions thereof, as seen at the input to the de-interleaver, for which errors can be completely corrected by the error correcting code, regardless of the number of errors within the errored DMT symbols. + +NOTE 1 – This is equivalent to the number of consecutive errored octets within any block of $(I_p - 1) \cdot D_p + 1$ octets, as seen at the input to the de-interleaver, for which errors can be completely corrected by the error correcting code, divided by $L_p/8$ , the number of octets loaded in a DMT symbol for latency path $p$ . The interleaver block length, $I_p$ , and interleaver depth, $D_p$ , are defined in clause 9.4, and the number of bits from latency path $p$ loaded into a DMT symbol, $L_p$ , is defined in clause 9.5.4. + +NOTE 2 – The value of $INP_p$ is given in terms of DMT symbols. The time span of impulse noise protection, in ms, varies with subcarrier spacing as determined by the profile (see clause 6) and with the CE length (see clause 10.4.4). + +The actual impulse noise protection $INP\_act_n$ of bearer channel # $n$ shall always be set to the value of the derived parameter $INP_p$ of the underlying PMS-TC path function (see Annex L). The receiver shall always ensure $INP\_act_n \geq INP\_min_n$ according to the definition of $INP_p$ regardless of any vendor-discretionary techniques including, for example, the use of erasure decoding. When the Reed-Solomon decoder in the receiver does not use erasure decoding, the $INP_p$ shall be computed as: + +$$INP\_no\_erasure_p = \frac{8 \times D_p \times \left\lceil \frac{R_p}{2 \times q_p} \right\rceil}{L_p} = \frac{S_p \times D_p \times \left\lceil \frac{R_p}{2 \times q_p} \right\rceil}{N_{FECp}} \text{ DMT symbols}$$ + +where parameters $D_p$ , $R_p$ , $L_p$ , and $q_p$ are defined in clauses 9.4 and 9.5.4. When erasure decoding is used, $INP_p$ might not equal $INP\_no\_erasure_p$ . + +For single latency with ROC mode, the value $INP\_no\_erasure_p$ for latency path #0 (the ROC) shall comply with: + +$$INP\_no\_erasure_0 \geq INPMIN-ROC \text{ (see clause 12.3.5.2.1.1)}$$ + +Within this equation, INPMIN-ROC is expressed in DMT symbols. + +The VTU-O shall calculate INPMIN-ROCus (in DMT symbols) from the CO-MIB value INPMIN-ROC-us (defined in clause 7.3.1.10.12 of [ITU-T G.997.1] in multiples of $T_{4k}$ ), and the VTU-R shall calculate INPMIN-ROCds (in DMT symbols) from the O-MSG 1 parameter INPMIN-ROC-ds value (defined in field #23 in multiples of $T_{4k}$ ) as follows: + +- For 4.3125 kHz subcarrier spacing: +INPMIN-ROC in DMT symbols = INPMIN-ROC in multiples of $T_{4k}$ . +- For 8.625 kHz subcarrier spacing: +INPMIN-ROC in DMT symbols = $2 \times$ (INPMIN-ROC in multiples of $T_{4k}$ ). + +with $T_{4k}$ as defined in clause 10.4.4. + +During initialization, the VTU-O, under direction from the CO-MIB, can set a bit in initialization to require that the VTU-R receiver select framing parameters so that $INP_p = INP\_no\_erasure_p$ on both latency paths. Regardless of whether this bit is set, the receiver shall always ensure $INP\_act_n \geq INP\_min_n$ . This bit is referred to as "INP\_no\_erasure\_required", bit 8 in the "Impulse noise protection" field in Table 12-51, clause 12.3.5.2.1.1. + +During initialization, the VTU-R declares if it is using erasure decoding on either latency path. This field is referred to as "Erasure decoding used" in Table 12-64, clause 12.3.5.2.2.3. + +Erasure decoding is vendor discretionary at both VTUs. + +## 9.7 Delay + +When the interleaver is disabled (interleaver depth = 1), the one-way delay between the $\alpha$ and $\beta$ interfaces shall not exceed 2 ms. + +The actual delay in milliseconds introduced by the interleaver to latency path $p$ shall be computed as: + +$$delay_p = \frac{S_p \times (D_p - 1)}{q_p \times f_s} \times \left( 1 - \frac{q_p}{N_{FECp}} \right) \text{ ms}$$ + +where $D_p$ is the interleaving depth set for the latency path $p$ , $S_p$ is the parameter defined in Table 9-8, $q_p$ is the number of interleaver blocks in an FEC codeword for latency path $p$ , $N_{FECp}$ is the FEC codeword size for latency path $p$ , and $f_s$ is the data symbol rate in ksymbols/s. + +The interleaver delay in milliseconds for the specific bearer channel $n$ is constrained by the value of $delay\_max_n$ defined in the CO-MIB. + +For single latency with ROC mode, the value $delay_p$ for latency path #0 (the ROC) shall comply with: + +$$delay_0 \leq 8 \text{ ms}$$ + +Additionally, the framing parameters of the latency path #0 (the ROC) shall be chosen such that the ROC is robust to repetitive impulse noise at a frequency of 120 Hz. This may be achieved by selecting the framing parameters such that: + +$$\frac{8 \times N_{FEC0} \times D_0}{L_0} \leq \left\lfloor \frac{f_s}{120 \text{ Hz}} \right\rfloor - 1$$ + +## 9.8 Bit error ratio (BER) + +The bit error ratio (BER), referenced to the output of the $\alpha/\beta$ interface of the receiver, shall not exceed $10^{-7}$ for any of the supported bearers. The VTU shall implement appropriate initialization and reconfiguration procedures to assure this value. + +## 9.9 Delay variation + +The delay variation occurring in an OLR on latency path $p$ . + +It is defined here as: + +$$DV_p = | (delay_{p\_H} \times L_{p\_H} - delay_{p\_L} \times L_{p\_L}) / L_{p\_H} |$$ + +where: + +$L_{p\_L}$ is the lower value of $L_p$ in an OLR procedure + +$L_{p\_H}$ is the higher value of $L_p$ in an OLR procedure + +$delay_{p\_L}$ = the actual delay in ms in the steady state corresponding with $L_{p\_L}$ + +$delay_p\_H$ = the actual delay in ms in the steady state corresponding with $L_p\_H$ + +The delay variation $DV_n$ of bearer channel #n shall always be set to the value of $DV_p$ of the underlying PMS-TC path function (see Annex L). + +# 10 Physical media dependent (PMD) function + +During showtime, the transmit PMD function shall transmit a number of data symbols per second that is dependent on the choice of CE length (see clause 10.4.4) and subcarrier spacing (see clause 10.4.2). For each data symbol, the transmit PMD function receives a symbol encoder input data frame (containing $L$ data bits) from the transmit PMS-TC function. The data frame shall then be symbol encoded as defined in clause 10.3. The symbol encoding will generate a complex value for each subcarrier in the MEDLEY set (either MEDLEYus or MEDLEYds, depending on the transmission direction, resulting in $NSC_{us}$ and $NSC_{ds}$ complex values respectively). These complex values shall be modulated into data symbols as defined in clause 10.4 to produce an analogue signal for transmission across the digital subscriber line. + +## 10.1 PMD functional model + +The functional model of the PMD sublayer is presented in Figure 10-1. In the transmit direction, the PMD sublayer receives input data frames from the PMS-TC sublayer via the $\delta$ interface as specified in clause 9.1. Each data frame contains an integer number of data bits equal to $L_0 + L_1$ to be modulated onto one DMT symbol. Prior to modulation, the incoming bits are encoded by the symbol encoder. The encoder divides the incoming bit stream into small groups of bits, where each group is assigned to modulate a specific subcarrier of the DMT signal. Each group is further encoded by the trellis encoder and mapped to a point in a signal constellation. The set of constellation points modulates the subcarriers of the DMT symbol using an IDFT. The number of bits assigned to each subcarrier is determined during the initialization procedure based on the SNR of the subcarrier and specific system configuration settings. After the IDFT, the resulting symbol is cyclically extended and windowed, and sent towards the transmission medium over the U interface. + +In the receive direction, the signal incoming from the transmission medium via the U interface is demodulated and decoded to extract the transmitted data frame. The data frame obtained from the decoder (denoted "Data frame (output)" in Figure 10-1) is sent to the PMS-TC sublayer via the $\delta$ interface. + +![Functional model of PMD sublayer diagram showing transmit and receive paths between PMS-TC and PMD sublayers.](beefc2239bc009e7b97963ac4f166db1_img.jpg) + +The diagram illustrates the functional model of the PMD sublayer, showing the flow of data between the PMS-TC sublayer and the PMD sublayer. The diagram is divided into two main sections: the transmit direction (top) and the receive direction (bottom). + +- Transmit Direction:** + - Data frames from the PMS-TC sublayer enter the PMD sublayer at the $\delta$ reference point. + - The data frames are processed by three parallel encoders: "Initialization symbol encoder (10.6)", "Sync symbol encoder (10.5)", and "Data symbol encoder (10.3)". + - The outputs of these encoders are combined and labeled $Z_i$ . + - $Z_i$ is then processed by a "Modulation (10.4)" block, which contains three sub-blocks: "Modulation by IDFT (10.4.3)", "Cyclic extension (10.4.4)", and "Windowing (10.4.4)". + - The output of the modulation block is labeled $x_n$ . + - $x_n$ is then processed by a "Hybrid" block. + - The output of the Hybrid block is sent to the transmission medium via the U interface at the U-x reference point. +- Receive Direction:** + - A signal from the transmission medium enters the PMD sublayer at the U-x reference point. + - The signal is processed by the "Hybrid" block. + - The output of the Hybrid block is then processed by a "Demodulation" block. + - The output of the Demodulation block is sent to the "Decoder" block. + - The output of the Decoder block is labeled "Data frame (output)" and is sent back to the PMS-TC sublayer at the $\delta$ reference point. + +The diagram also includes labels for the sublayers: "PMS-TC" and "PMD". The reference points are labeled " $\delta$ reference point" and "U-x reference point". The diagram is identified by the code "G.993.2\_F10-1" in the bottom right corner. + +Functional model of PMD sublayer diagram showing transmit and receive paths between PMS-TC and PMD sublayers. + +Figure 10-1 – Functional model of PMD sublayer + +## 10.2 DMT superframe + +The transmit PMD function shall use the DMT superframe structure shown in Figure 10-2. Each DMT superframe shall be composed of 256 data frames, numbered from 0 to 255, followed by a single sync frame. The content of the sync frame is dependent on whether timing for on-line reconfiguration is being signalled (see clause 10.5.3). The data frames are modulated onto 256 data symbols, and the sync frame is modulated onto a sync symbol as defined in clause 10.5.1. The sync symbol provides a time marker for on-line reconfiguration (see clause 13). + +![Diagram of DMT superframe structure showing 256 data frames (0 to 255) followed by a sync frame. The diagram shows data frames 0, 1, 34, 35, 254, 255, and a sync frame, with ellipses indicating the sequence. A label 'no PMS-TC data' is present below the sync frame.](4a2b39fa33747a6553031cfe1e0947fa_img.jpg) + +DMT superframe + +| | | | | | | | | | +|-----------------|-----------------|---|------------------|------------------|---|-------------------|-------------------|-------------------| +| data frame
0 | data frame
1 | } | data frame
34 | data frame
35 | } | data frame
254 | data frame
255 | sync frame | +| | | | | | | | | no PMS-TC
data | + +G.993.2\_F10-2 + +Diagram of DMT superframe structure showing 256 data frames (0 to 255) followed by a sync frame. The diagram shows data frames 0, 1, 34, 35, 254, 255, and a sync frame, with ellipses indicating the sequence. A label 'no PMS-TC data' is present below the sync frame. + +**Figure 10-2 – DMT superframe structure** + +NOTE – The duration of a superframe depends on the subcarrier spacing and value of the cyclic extension (see clause 10.4). When the subcarrier spacing is 4.3125 kHz and the mandatory cyclic extension value is used (5/64), the duration of a superframe is 64.25 ms. + +## 10.3 Symbol encoder for data symbols + +The symbol encoder for data symbols is shown as part of the transmit PMD function in Figure 10-1. The symbol encoder for data symbols consists of the following functions: + +- Tone ordering; +- Trellis coding; +- Constellation mapping; +- Constellation point scaling. + +### 10.3.1 Tone ordering + +During initialization, the receive PMD function shall calculate the numbers of bits and the relative gains to be used for every subcarrier in the MEDLEY set (either MEDLEYus or MEDLEYds, depending on the transmission direction), as well as the order in which subcarriers are assigned bits (i.e., the tone ordering). The calculated bits and gains and the tone ordering shall be sent back to the transmit PMD function during the channel analysis and exchange phase of initialization (see clause 12.3.5.2). The number of subcarriers in MEDLEYus and MEDLEYds is denoted by $NSC_{us}$ and $NSC_{ds}$ , respectively. + +The pairs of bits and relative gains are defined, in ascending order of frequency or subcarrier index $i$ , as a bit allocation table $b$ and gain table $g$ (i.e., $b_i$ and $g_i$ , for all subcarrier indices $i$ that belong to the MEDLEY set). If trellis coding is used, the receive PMD function shall include an even number of 1-bit subcarriers ( $NCONEBIT$ ) in the bit allocation table $b$ . + +The tone ordering table $t$ is defined as the sequence $\{t_k\}$ in which subcarriers from the MEDLEY set are assigned bits from the input bitstream ( $t_k$ for $k = 1$ to $NSC_{us}$ for the upstream tones, $k = 1$ to $NSC_{ds}$ for the downstream tones) with constellation mapping beginning on the subcarrier with index $i = t_1$ and ending on the subcarrier with index $i = t_{NSC}$ (for example, $t_{75} = 160$ means that the subcarrier with index 160 is the 75th subcarrier to be assigned bits from the input bit stream). The tone ordering table $t$ shall be created and exchanged during initialization (O-PMD, R-PMD messages, see clause 12.3.5.2) and shall remain unchanged until the next initialization. + +If the ROC is enabled, the bits of buffer $L_0$ and buffer $L_1$ shall not share the same subcarrier. With + +trellis encoding, this means that all the bits $u_1$ to $u_{z'}$ that are used to encode a 4-dimensional symbol belong to the same buffer (see clause 10.3.2). + +Following reception of the tables $b$ , $g$ and $t$ , the transmit PMD function shall calculate a reordered bit table $b'$ and a reordered tone table $t'$ from the original tables $b$ and $t$ . Constellation mapping shall occur in sequence according to the reordered tone table $t'$ , with the number of bits per subcarrier as defined by the original bit table $b$ . Trellis coding shall occur according to the reordered bit table $b'$ and reordered tone table $t'$ . + +If trellis coding is not used, $b' = b$ and $t' = t$ . + +If trellis coding is used, the reordering of table $t$ shall be performed by the transmit PMD function. The reordered tone table $t'$ shall be generated according to the following rules: + +- Indices of all subcarriers supporting 0 bits or 2 or more bits appear first in $t'$ , in the same order as in table $t$ ; +- Indices of all subcarriers supporting 1 bit appear last in table $t'$ , in the same order as in table $t$ . + +If the bit allocation does not include any 1-bit subcarriers, the reordered tone table $t'$ is identical to the original tone table $t$ . + +The (even number of) 1-bit subcarriers shall be paired to form 2-dimensional constellation points as input to the trellis encoder. The pairing shall be determined by the order in which the 1-bit subcarriers appear in the original tone ordering table $t$ . + +The table $b'$ shall be generated by reordering the entries of table $b$ according to the following rules: + +- The first $NCONEBIT/2$ entries of $b'$ shall be 0, where $NCONEBIT$ (by definition, even) is the number of subcarriers supporting 1 bit; +- The next entries of $b'$ shall be 0, corresponding to all subcarriers that support 0 bits; +- The next entries of $b'$ shall be non-zero, corresponding to the subcarriers that support two or more bits. The entries shall be determined using the new tone table $t'$ in conjunction with the original bit table $b$ ; +- The last $NCONEBIT/2$ entries of $b'$ correspond to the paired 1-bit constellations (i.e., 2 bits per entry). + +The tables $b'$ and $t'$ shall be calculated from the original tables $b$ and $t$ as shown in the subcarrier pairing and bit reordering processes below. + +``` + +/*** CONSTRUCT THE TONE RE-ORDERING TABLE ***/ +/* +Tone ordering table is denoted as array 't' and tone re-ordering +table is denoted as array 'tp'. The indices to these arrays are +denoted as 't_index' and 'tp_index', respectively. +*/ +/* +Fill out tone re-ordering table with entries of tone ordering table +but skip 1-bit tones. +*/ +tp_index = 1; +for (t_index = 1; t_index ≤ NSC; t_index++) { + tone = t[t_index]; + bits = b[tone]; + if (bits != 1) { + tp[tp_index++] = tone; + } +} +/* +Add the 1-bit tones to the end of tone re-ordering table. +*/ + +``` + +``` + +for (t_index = 1; t_index ≤ NSC; t_index++) { + tone = t[t_index]; + bits = b[tone]; + if (bits == 1) { + tp[tp_index++] = tone; + } +} +/* RE-ORDERING THE BIT ARRAY */ +/* +The bit table is denoted as array 'b' and the ordered bit table is +denoted as array 'bp'. +The indexes to these arrays are denoted as 'b_index' and bp_index', +respectively. +*/ +/* First, count the number of loaded tones and also 1-bit tones. */ +NCONEBIT = 0; /* NCONEBIT is the number of subcarriers with 1 bit */ +NCUSED = 0; /* NCUSED is the number of loaded subcarriers */ +for (all i ∈ MEDLEY set) { + if (b[i] > 0) { + NCUSED++; + } + if (b[i] == 1) { + NCONEBIT++; + } +} +/* Fill initial zero entries for unloaded tones and half the number of +1-bit tones */ +for (bp_index = 1; bp_index ≤ (NSC - (NCUSED - NCONEBIT/2)); +bp_index++) { + bp[bp_index] = 0; +} +for (tp_index = 1; tp_index ≤ NSC; tp_index++) { + tone = tp[tp_index]; + bits = b[tone]; + if (bits == 0) { + /* skip unloaded tones */ + } + if (bits == 1) { + /* pair 2 consecutive 1-bit tones and add a + single entry with 2 bits */ + bp[bp_index++] = 2; + tp_index++; + } + if (bits > 1) { + bp[bp_index++] = bits; + } +} + +``` + +Figure 10-3 presents an example to illustrate the tone reordering and bit reordering procedures, and the pairing of 1-bit subcarriers for trellis encoding. + +Tone ordering table $t$ (as determined by the receive PMD function, $NSC=23$ ) + +| | | | | | | | | | | | | | | | | | | | | | | | +|---|----|----|---|----|----|---|---|----|----|---|----|----|---|---|----|----|---|----|----|---|----|----| +| 7 | 14 | 21 | 4 | 11 | 18 | 1 | 8 | 15 | 22 | 5 | 12 | 19 | 2 | 9 | 16 | 23 | 6 | 13 | 20 | 3 | 10 | 17 | +|---|----|----|---|----|----|---|---|----|----|---|----|----|---|---|----|----|---|----|----|---|----|----| + +Bit table $b$ (as determined by the receive PMD function, 37 bits/symbol, natural order of sub-carrier indices starting from 1) + +| | | | | | | | | | | | | | | | | | | | | | | | +|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| +| 0 | 1 | 2 | 3 | 2 | 1 | 2 | 1 | 0 | 2 | 0 | 2 | 1 | 1 | 3 | 3 | 3 | 2 | 1 | 0 | 2 | 3 | 2 | +|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| + +Tone reordered table $t'$ (moving 1-bit sub-carriers to the end of the table) + +| | | | | | | | | | | | | | | | | | | | | | | | +|---|----|---|----|----|---|----|----|---|----|---|----|----|----|---|----|----|----|---|----|---|---|----| +| 7 | 21 | 4 | 11 | 18 | 1 | 15 | 22 | 5 | 12 | 9 | 16 | 23 | 20 | 3 | 10 | 17 | 14 | 8 | 19 | 2 | 6 | 13 | +|---|----|---|----|----|---|----|----|---|----|---|----|----|----|---|----|----|----|---|----|---|---|----| + +Reordered bit table $b'$ (moving 0-bit sub-carriers to the beginning of the table) + +| | | | | | | | | | | | | | | | | | | | | | | | +|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|-----|-----|-----| +| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 | 3 | 2 | 3 | 3 | 2 | 2 | 3 | 2 | 2 | 2 | 3 | 1+1 | 1+1 | 1+1 | +|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|-----|-----|-----| + +Trellis pairs (encoding 25 data bits into 37 trellis bits) and bit mapping to sub-carriers + +![Diagram showing trellis pairs and bit mapping to sub-carriers. It consists of several pairs of boxes representing trellis states, with arrows pointing down to specific sub-carrier indices. The sub-carrier indices are grouped by the trellis pair they belong to. The last part of the diagram shows the text G.993.2_F010-3.](4aeaa51a3999fab21171224e238cb571_img.jpg) + +The diagram illustrates the mapping of trellis pairs to sub-carriers. It shows a sequence of trellis pairs (represented by two boxes) and the corresponding sub-carrier indices they map to. The mapping is as follows: + +- Trellis pair (2, 2) maps to sub-carriers 7 and 21. +- Trellis pair (3, 2) maps to sub-carriers 4, 11, 18, 1, 15, and 22. (Note: The first '0' in the bit table is skipped in this mapping). +- Trellis pair (3, 3) maps to sub-carriers 5, 12, 9, 16, 23, 20, 3, and 10. (Note: The second '0' in the bit table is skipped in this mapping). +- Trellis pair (2, 2) maps to sub-carriers 17, 14, and 8. +- Trellis pair (3, 1+1) maps to sub-carriers 19, 2, 6, and 13. +- Trellis pair (1+1, 1+1) maps to sub-carriers 19, 2, 6, and 13. + +The text G.993.2\_F010-3 is shown at the bottom right. + +Diagram showing trellis pairs and bit mapping to sub-carriers. It consists of several pairs of boxes representing trellis states, with arrows pointing down to specific sub-carrier indices. The sub-carrier indices are grouped by the trellis pair they belong to. The last part of the diagram shows the text G.993.2\_F010-3. + +Figure 10-3 – Example of tone ordering and pairing of one-bit subcarriers + +If on-line reconfiguration changes the number or indices of 0-bit subcarriers or 1-bit subcarriers, then tables $t'$ and $b'$ shall be recalculated from the updated table $b$ and the original table $t$ . + +The symbol encoder takes $L$ bits per symbol from the PMS-TC sublayer. If trellis coding is used, the $L$ bits shall be encoded into a number of bits $L'$ matching the bit allocation table $b$ and the reordered bit allocation table $b'$ , i.e., into a number of bits equal to $L' = \sum b'_i = \sum b_i$ . The values of $L$ and $L'$ relate as: + +$$L' = \sum b'_i = \sum b_i = L + \left\lceil \frac{NCUSED - \frac{NCONEBIT}{2}}{2} \right\rceil + 4$$ + +with the $\lceil x \rceil$ notation representing rounding to the next higher integer, and $NCUSED$ representing the number of subcarriers actually used for data transmission (with $b_i > 0$ ). The added 4 bits are to return the trellis to the zero state at the end of the DMT symbol, as described in clause 10.3.2.2. + +The above relationship shows that using the 1-bit subcarrier pairing method, on average, one trellis overhead bit is added per set of four 1-bit subcarriers, i.e., one trellis overhead bit per 4-dimensional constellation. + +In case trellis coding is not used, the value of $L$ shall match the bit allocation table, i.e.: + +$$L = \sum b_i$$ + +NOTE – A complementary tone reordering procedure should be performed in the receive PMD function. It is not necessary, however, to send the reordered bit table $b'$ and the reordered tone table $t'$ to the receive PMD function because they are generated in a deterministic way from the bit allocation table and tone ordering tables originally generated in the receive PMD function, and therefore the receive PMD function has all the information necessary to perform the constellation de-mapping and trellis decoding (if used). + +### 10.3.2 Trellis encoder + +The trellis encoder shall use block processing of Wei's 16-state 4-dimensional trellis code (see Figure 10-6) to improve system performance. + +#### 10.3.2.1 Bit extraction + +Bits from the data frame buffer shall be extracted in sequential order according to the bit allocation table $b'$ . The first bit of the data frame shall be extracted first. Because of the 4-dimensional nature of the code, the extraction is based on pairs of consecutive $b'$ entries, rather than on individual ones, as in the non-trellis-coded case. Furthermore, due to the constellation expansion associated with coding, the bit allocation table, $b'$ , specifies the number of coded bits per subcarrier, which can be any integer from 2 to 15. + +Trellis coding shall be performed on pairs of consecutive $b'$ values, starting with the first entry in the $b'$ table. If the number of non-zero entries in the $b'$ table is odd, the value $b'_0$ shall be prepended to the reordered bit table $b'$ first to make an integer number of pairs and shall be set to ZERO. For subcarriers with 1-bit constellations, each (1+1)-bit $b'$ entry will be mapped on two subcarriers, as described in Figure 10-3. + +Given a pair $(x, y)$ , $x + y - 1$ bits (reflecting a constellation expansion of 1 bit per 4 dimensions, or one half bit per subcarrier) are extracted from the data frame buffer, except for the last two 4-dimensional symbols. These $z = x + y - 1$ bits ( $t_z, t_{z-1}, \dots, t_1$ ) are used to form the binary word $u$ as shown in Table 10-1. Refer to clause 10.3.2.2 for the reason behind the special form of the word $u$ for the case $x = 0, y > 1$ . + +**Table 10-1 – Forming the binary word $u$** + +| Condition | Binary word/comment | +|---------------------------------------------------------------------|-------------------------------------------------------| +| $x > 1, y > 1$ | $u = (t_z, t_{z-1}, \dots, t_1)$ | +| $x = 1, y \geq 1$ | Condition not allowed | +| $x = 0, y > 1$ | $u = (t_z, t_{z-1}, \dots, t_2, 0, t_1, 0)$ | +| $x = 0, y = 0$ | Bit extraction not necessary, no data bits being sent | +| $x = 0, y = 1$ | Condition not allowed | +| NOTE – $t_1$ is the first bit extracted from the data frame buffer. | | + +The last two 4-dimensional symbols in each DMT symbol shall be chosen to force the convolutional encoder state to the zero state. For each of these symbols, the two LSBs of $u$ are predetermined, and only $(x + y - 3)$ bits shall be extracted from the data frame buffer and shall be allocated to $t_3, t_4, \dots, t_z$ . NOTE – The above requirements imply a minimum size of the $b'$ table of 4 non-zero entries. The minimum number of non-zero entries in the corresponding $b$ table could be higher. + +#### 10.3.2.2 Bit conversion + +The binary word $u = (u_{z'}, u_{z'-1}, \dots, u_1)$ extracted LSB first from the data frame buffer determines two binary words $v = (v_{z'-y}, \dots, v_0)$ and $w = (w_{y-1}, \dots, w_0)$ , which are inserted LSB first in the encoded data bits buffer and used to look up constellation points in the constellation mapper (see Figure 10-4). + +![Figure 10-4: Relationship of trellis encoder and constellation mapping. The diagram shows a flow from a 'data frame buffer' containing bits u_{z'}...u_1 to a 'Trellis encoder'. Above the first buffer, it says 'extract L bits per symbol'. The output of the trellis encoder goes to an 'encoded data bits buffer' containing two parts: w_{y-1}...w_0 and v_{z'-y}...v_0. Above this buffer, it says 'extract L' = \sum b'_i = \sum b_i bits per symbol'. The output of the encoded buffer goes to 'Constellation mapping'. A label 'G.993.2_F10-4' is in the bottom right corner.](8a781a0a8c956859f63a1ca7f2bb1644_img.jpg) + +Figure 10-4: Relationship of trellis encoder and constellation mapping. The diagram shows a flow from a 'data frame buffer' containing bits u\_{z'}...u\_1 to a 'Trellis encoder'. Above the first buffer, it says 'extract L bits per symbol'. The output of the trellis encoder goes to an 'encoded data bits buffer' containing two parts: w\_{y-1}...w\_0 and v\_{z'-y}...v\_0. Above this buffer, it says 'extract L' = \sum b'\_i = \sum b\_i bits per symbol'. The output of the encoded buffer goes to 'Constellation mapping'. A label 'G.993.2\_F10-4' is in the bottom right corner. + +**Figure 10-4 – Relationship of trellis encoder and constellation mapping** + +NOTE – For convenience of description, the constellation mapper identifies these $x$ and $y$ bits with a label whose binary representation is $(v_{b-1}, v_{b-2}, \dots, v_1, v_0)$ . The same constellation mapping rules apply to both the $v$ (with $b = x$ ) and the $w$ (with $b = y$ ) vector generated by the trellis encoder. + +For the usual case of $x > 1$ and $y > 1$ , $z' = z = x + y - 1$ , and $v$ and $w$ contain $x$ and $y$ bits respectively. For the special case of $x = 0$ and $y > 1$ , $z' = z + 2 = y + 1$ , $v = (v_1, v_0) = (0, 0)$ and $w = (w_{y-1}, \dots, w_0)$ . The bits $(u_3, u_2, u_1)$ determine $(v_1, v_0)$ and $(w_1, w_0)$ according to Figure 10-5. + +The convolutional encoder shown in Figure 10-5 is a systematic encoder (i.e., $u_1$ and $u_2$ are passed through unchanged) as shown in Figure 10-6. The convolutional encoder state $(S_3, S_2, S_1, S_0)$ is used to label the states of the trellis shown in Figure 10-8. At the beginning of a DMT symbol, the convolutional encoder state shall be initialized to $(0, 0, 0, 0)$ . + +The remaining bits of $v$ and $w$ are obtained from the less significant and more significant parts of $(u_{z'}, u_{z'-1}, \dots, u_4)$ , respectively. When $x > 1$ and $y > 1$ , $v = (u_{z'-y+2}, u_{z'-y+1}, \dots, u_4, v_1, v_0)$ and $w = (u_{z'}, u_{z'-1}, \dots, u_{z'-y+3}, w_1, w_0)$ . When $x = 0$ , the bit extraction and conversion algorithms result in $v_1 = v_0 = 0$ . The binary word $v$ shall be input first to the constellation mapper, and then the binary word $w$ . + +In order to force the final state of the convolutional encoder to the zero state $(0, 0, 0, 0)$ , the two LSBs $u_1$ and $u_2$ of the final two 4-dimensional symbols in the DMT symbol are constrained to $u_1 = S_1 \oplus S_3$ , and $u_2 = S_2$ . + +![Figure 10-5: Conversion of u to v and w. The diagram shows a 'Convolutional encoder' block taking inputs u1, u2, u3 and producing intermediate outputs u0, u1, u2. These intermediate outputs are then processed by a second block containing linear equations to produce final outputs v0, v1, w0, w1. Above this main structure, several other input/output pairs are shown with ellipses, indicating a repeating pattern: u_{z'} to w_{z'-1}, u_{z'-1} to w_{z'-2}, ..., u_{z-p+3} to w_2, u_{z-p+2} to v_{z-p}, u_{z-p+1} to v_{z-p-1}, ..., u_4 to v_2.](9c80cf99954eb0142f694456d39fae4b_img.jpg) + +$$\begin{aligned} + v_1 &= u_1 \oplus u_3 \\ + v_0 &= u_3 \\ + w_1 &= u_0 \oplus u_1 \oplus u_2 \oplus u_3 \\ + w_0 &= u_2 \oplus u_3 + \end{aligned}$$ + +G.993.2\_F10-5 + +Figure 10-5: Conversion of u to v and w. The diagram shows a 'Convolutional encoder' block taking inputs u1, u2, u3 and producing intermediate outputs u0, u1, u2. These intermediate outputs are then processed by a second block containing linear equations to produce final outputs v0, v1, w0, w1. Above this main structure, several other input/output pairs are shown with ellipses, indicating a repeating pattern: u\_{z'} to w\_{z'-1}, u\_{z'-1} to w\_{z'-2}, ..., u\_{z-p+3} to w\_2, u\_{z-p+2} to v\_{z-p}, u\_{z-p+1} to v\_{z-p-1}, ..., u\_4 to v\_2. + +Figure 10-5 – Conversion of $u$ to $v$ and $w$ + +![Figure 10-6: Convolutional encoder: Finite state machine representation. This is a block diagram of a finite state machine. It has three horizontal lines for inputs u2, u1, and u0 on the left and outputs u2, u1, and u0 on the right. The state is represented by three delay blocks labeled D, each followed by an adder block labeled with a '+' sign. The state elements are labeled S2, S1, S3, and S0. Feedback loops connect the outputs of the adders back to the inputs of the delay blocks.](8ba270d9a35a905e16a9b78e6b3ad2b8_img.jpg) + +G.993.2\_F10-6 + +Figure 10-6: Convolutional encoder: Finite state machine representation. This is a block diagram of a finite state machine. It has three horizontal lines for inputs u2, u1, and u0 on the left and outputs u2, u1, and u0 on the right. The state is represented by three delay blocks labeled D, each followed by an adder block labeled with a '+' sign. The state elements are labeled S2, S1, S3, and S0. Feedback loops connect the outputs of the adders back to the inputs of the delay blocks. + +Figure 10-6 – Convolutional encoder: Finite state machine representation + +#### 10.3.2.3 Coset partitioning and trellis diagram + +In a trellis code modulation system, the expanded constellation may be labelled and partitioned into subsets ("cosets") using a technique called mapping by set-partitioning. The 4-dimensional cosets in Wei's code can each be written as the union of two Cartesian products of two 2-dimensional cosets. + +For example, $C_4^0 = (C_2^0 \times C_2^0) \cup (C_2^3 \times C_2^3)$ . The four constituent 2-dimensional cosets, denoted by 0, 1, 2, and 3 for $C_2^0, C_2^1, C_2^2, C_2^3$ , respectively, are shown in Figure 10-7. + +The constellation mapping ensures that the two LSBs of a constellation point comprise the index $i$ of the 2-dimensional coset $C_2^i$ in which the constellation point lies. The bits $(v_1, v_0)$ and $(w_1, w_0)$ are in fact the binary representations of this index. + +The three bits $(u_2, u_1, u_0)$ are used to select one of the eight possible 4-dimensional cosets. The eight cosets are labelled $C_4^i$ where $i$ is the integer with binary representation $(u_2, u_1, u_0)$ . The additional bit $u_3$ (see Figure 10-5) determines which one of the two Cartesian products of 2-dimensional cosets is chosen from the 4-dimensional coset. The relationship is shown in Table 10-2. The bits $(v_1, v_0)$ and $(w_1, w_0)$ are computed from $(u_3, u_2, u_1, u_0)$ using the linear equations given in Figure 10-5. + +![A 2D coordinate system with x and y axes. The origin is at the center. The axes are labeled with numbers 1, 3, 1, 3, 1, 3, 1, 3 on the positive x-axis and 0, 2, 0, 2, 0, 2, 0, 2 on the positive y-axis. The same sequence of numbers is repeated on the negative axes. The label G.993.2_F10-7 is at the bottom right.](2cca454bbea734b85b2a785da04388f9_img.jpg) + +A 2D coordinate system with x and y axes. The origin is at the center. The axes are labeled with numbers 1, 3, 1, 3, 1, 3, 1, 3 on the positive x-axis and 0, 2, 0, 2, 0, 2, 0, 2 on the positive y-axis. The same sequence of numbers is repeated on the negative axes. The label G.993.2\_F10-7 is at the bottom right. + +Figure 10-7 – Mapping of 2-dimensional cosets + +Table 10-2 – Relation between 4-dimensional and 2-dimensional cosets + +| 4-D coset | $u_3$ | $u_2$ | $u_1$ | $u_0$ | $v_1$ | $v_0$ | $w_1$ | $w_0$ | 2-D cosets | +|-----------|-------|-------|-------|-------|-------|-------|-------|-------|----------------------| +| $C_4^0$ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | $C_2^0 \times C_2^0$ | +| | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | $C_2^3 \times C_2^3$ | +| $C_4^4$ | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | $C_2^0 \times C_2^3$ | +| | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | $C_2^3 \times C_2^0$ | +| $C_4^2$ | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | $C_2^2 \times C_2^2$ | +| | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | $C_2^1 \times C_2^1$ | +| $C_4^6$ | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | $C_2^2 \times C_2^1$ | +| | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | $C_2^1 \times C_2^2$ | +| $C_4^1$ | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | $C_2^0 \times C_2^2$ | +| | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | $C_2^3 \times C_2^1$ | +| $C_4^5$ | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | $C_2^0 \times C_2^1$ | +| | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | $C_2^3 \times C_2^2$ | +| $C_4^3$ | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | $C_2^2 \times C_2^0$ | +| | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | $C_2^1 \times C_2^3$ | +| $C_4^7$ | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | $C_2^2 \times C_2^3$ | +| | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | $C_2^1 \times C_2^0$ | + +![Trellis diagram showing state transitions between current states S and next states T. The diagram has 16 states labeled 0-F. Each state has 4 outgoing branches. Labels for states and branches are provided on the left and right sides of the diagram.](7ec36a0a9788e1cb33df5372695498c8_img.jpg) + +The trellis diagram illustrates the transitions between 16 states, labeled 0 through F. Each state is represented by a 4-dimensional coset $(S_3, S_2, S_1, S_0)$ for the current state and $(T_3, T_2, T_1, T_0)$ for the next state. The diagram shows 4 outgoing branches from each state, with the leftmost label for each state indicating the uppermost branch. + +| State | Current State $(S_3, S_2, S_1, S_0)$ | Next State $(T_3, T_2, T_1, T_0)$ | +|-------|--------------------------------------|-----------------------------------| +| 0 | 0246 | 0426 | +| 1 | 1357 | 2604 | +| 2 | 2064 | 4062 | +| 3 | 3175 | 6240 | +| 4 | 4602 | 1537 | +| 5 | 5713 | 3715 | +| 6 | 6420 | 5173 | +| 7 | 7531 | 7351 | +| 8 | 2064 | 2604 | +| 9 | 3175 | 0426 | +| A | 0246 | 6240 | +| B | 1357 | 4062 | +| C | 6420 | 3715 | +| D | 7531 | 1537 | +| E | 4602 | 7351 | +| F | 5713 | 5173 | + +G.992.3(15)\_F10-8 + +Trellis diagram showing state transitions between current states S and next states T. The diagram has 16 states labeled 0-F. Each state has 4 outgoing branches. Labels for states and branches are provided on the left and right sides of the diagram. + +**Figure 10-8 – Trellis diagram** + +Figure 10-8 shows the trellis diagram based on the finite state machine in Figure 10-6, and the one-to-one correspondence between $(u_2, u_1, u_0)$ and the 4-dimensional cosets. In Figure 10-8, $S = (S_3, S_2, S_1, S_0)$ represents the current state, while $T = (T_3, T_2, T_1, T_0)$ represents the next state in the finite state machine. $S$ is connected to $T$ in the trellis diagram by a branch determined by the values of $u_2$ and $u_1$ . The branch is labelled with the 4-dimensional coset specified by the values of $u_2, u_1$ (and $u_0 = S_0$ , see Figure 10-6). To make the trellis diagram more readable, the indices of the 4-dimensional coset labels are listed next to the starting and end points of the branches, rather than on the branches themselves. The leftmost label corresponds to the uppermost branch for each state. The trellis diagram may be used when decoding the trellis code by the Viterbi algorithm. + +### 10.3.3 Constellation mapper + +The constellation mapper maps a set of bits to a constellation point. The data buffer contains $\sum_i b_i$ bits, which may or may not be trellis coded. Bits shall be extracted, as defined in clause 10.3.3.1, from the data buffer or from a pseudo-random binary sequence (PRBS) generator. The extracted bits shall be mapped to constellation points as defined in clause 10.3.3.2. + +#### 10.3.3.1 Bit extraction + +Bits shall be extracted from the data buffer or from a PRBS generator in the order defined by the tone ordering table. + +For each subcarrier $i$ in the MEDLEY set with $b_i > 0$ and $g_i > 0$ (linear scale), the encoder shall extract $b = b_i$ bits from the data buffer. The number of bits extracted ( $b_i$ ) for each subcarrier is determined by the bit allocation table. The set of $b$ extracted bits shall be represented as a binary word ( $v_{b-1} v_{b-2} \dots v_1 v_0$ ), where the first bit extracted shall be $v_0$ , the LSB. The encoder shall select a point $(X, Y)$ from the constellation based on the $b$ -bit word ( $v_{b-1} v_{b-2} \dots v_1 v_0$ ). + +For each monitored subcarrier (i.e., subcarriers in the MEDLEY set with $b_i = 0$ and $g_i > 0$ ) and for each subcarrier used as a pilot tone during showtime (see clause 12.3.5.2.2.4), no bits shall be extracted from the data buffer. Instead, the encoder shall extract $b = 2$ bits ( $v_1 v_0$ ) from the PRBS generator, where the first bit extracted shall be $v_0$ . For the pilot tone subcarrier(s), the bits extracted from the PRBS generator shall be overwritten by the modulator with a fixed 4-quadrature amplitude modulation (QAM) constellation point corresponding to the bits 00 (i.e., the two bits from the PRBS generator are effectively ignored). + +The PRBS generator shall be defined by: + +$$\begin{aligned} d_n &= 1 \text{ for } n = 1 \text{ to } n = 23; \text{ and} \\ d_n &= d_{n-18} \oplus d_{n-23} \text{ for } n > 23. \end{aligned}$$ + +The PRBS generator shall be reset at the beginning of showtime. Upon reset of the PRBS, $d_1$ shall be the first bit extracted, followed by $d_2, d_3$ , etc. For each data symbol, the number of bits extracted from the PRBS generator shall be twice the number of subcarriers in the MEDLEY set that have $b_i = 0$ plus twice the number of showtime pilot tones. No bits shall be extracted from the PRBS generator during sync symbols. + +For a given subcarrier $i$ not in the MEDLEY set ( $b_i = 0$ by definition), no bits shall be extracted from the data buffer and no bits shall be extracted from the PRBS generator. Instead, the constellation mapper may select a vendor-discretionary $(X, Y)$ point (which may change from symbol to symbol and which does not necessarily coincide with a constellation point). + +The described bit extraction mechanism is relevant only during showtime. + +#### 10.3.3.2 Constellations + +An algorithmic constellation mapper shall be used to construct subcarrier QAM constellations with a minimum number of bits equal to 1 and a maximum number of bits equal to 15. + +The constellation points are denoted $(X, Y)$ . $X$ and $Y$ shall lie at the odd integers $\pm 1, \pm 3, \pm 5$ , etc. For convenience of illustration, each constellation point in Figures 10-9 through 10-13 is labelled by an integer whose unsigned binary representation is $(v_{b-1} v_{b-2} \dots v_1 v_0)$ . + +##### 10.3.3.2.1 Even values of $b$ + +For even values of $b$ , the integer values $X$ and $Y$ of the constellation point $(X, Y)$ shall be determined from the $b$ bits $(v_{b-1}, v_{b-2}, \dots, v_1, v_0)$ as follows. $X$ and $Y$ shall be odd integers with twos-complement binary representations $(v_{b-1} v_{b-3} \dots v_1 1)$ and $(v_{b-2} v_{b-4} \dots v_0 1)$ , respectively. The MSBs, $v_{b-1}$ and $v_{b-2}$ , shall be the sign bits for $X$ and $Y$ , respectively. Figure 10-9 shows example constellations for $b = 2$ and $b = 4$ . + +![Figure 10-9: Constellation labels for b = 2 and b = 4. The left diagram shows a 2-bit constellation with points labeled 0, 1, 2, 3 at coordinates (+1, +1), (+1, -1), (-1, +1), and (-1, -1) respectively. The right diagram shows a 4-bit constellation with 16 points labeled 0 through 15, arranged in a 4x4 grid with coordinates ranging from -3 to +3 on both axes. The labels follow a recursive pattern where each 2-bit label n is replaced by a 2x2 block of 4-bit labels: 4n+1, 4n+3 in the top row and 4n, 4n+2 in the bottom row.](a0ca2e895d28cff7c1bbb8e7bad3b0a1_img.jpg) + +Figure 10-9: Constellation labels for b = 2 and b = 4. The left diagram shows a 2-bit constellation with points labeled 0, 1, 2, 3 at coordinates (+1, +1), (+1, -1), (-1, +1), and (-1, -1) respectively. The right diagram shows a 4-bit constellation with 16 points labeled 0 through 15, arranged in a 4x4 grid with coordinates ranging from -3 to +3 on both axes. The labels follow a recursive pattern where each 2-bit label n is replaced by a 2x2 block of 4-bit labels: 4n+1, 4n+3 in the top row and 4n, 4n+2 in the bottom row. + +Figure 10-9 – Constellation labels for $b = 2$ and $b = 4$ + +NOTE – The 4-bit constellation may be obtained from the 2-bit constellation by replacing each label $n$ by the $2 \times 2$ block of labels: + +$$\begin{array}{cc} 4n+1 & 4n+3 \\ 4n & 4n+2 \end{array}$$ + +The same procedure may be used to construct the larger even-bit constellations recursively. The constellations obtained for even values of $b$ are square in shape. + +##### 10.3.3.2.2 Odd values of $b$ + +###### 10.3.3.2.2.1 $b = 1$ + +Figure 10-10 shows the constellation for the case $b = 1$ . + +![Figure 10-10: Constellation labels for b = 1. The diagram shows a 1-bit constellation with two points labeled 0 and 1. Point 0 is at coordinate (+1, +1) and point 1 is at coordinate (-1, -1). The axes are labeled with +1 and -1.](39a8f00d10b50463cb1d9e79a8124a27_img.jpg) + +Figure 10-10: Constellation labels for b = 1. The diagram shows a 1-bit constellation with two points labeled 0 and 1. Point 0 is at coordinate (+1, +1) and point 1 is at coordinate (-1, -1). The axes are labeled with +1 and -1. + +Figure 10-10 – Constellation labels for $b = 1$ + +When trellis coding is used, the 2-bit words generated by the trellis encoder shall be mapped on two 1-bit subcarriers using the same labelling for 1-bit and 2-bit constellations as described above. An example for $v_0 = 1$ and $v_1 = 0$ is shown in Figure 10-11, in which the constellation for the 2-bit word is on the right-hand side of the diagram. + +![Figure 10-11: Combination of a pair of 1-bit constellations to build a 2-bit constellation. The diagram shows three coordinate planes. The first plane (X1, Y1) has an open circle at (1, 1) and a solid dot at (-1, -1), labeled v0=1. The second plane (X2, Y2) has a solid dot at (1, 1) and an open circle at (-1, -1), labeled v1=0. The third plane shows the combined constellation with axes (X1+Y1)/2 and (X2+Y2)/2. It has open circles at (1, 1) and (-1, -1), and solid dots at (1, -1) and (-1, 1), labeled v1=0, v0=1. A small label G.993.2_F10-11 is present.](4e525151b89a2f87f31d869491a817d8_img.jpg) + +Figure 10-11: Combination of a pair of 1-bit constellations to build a 2-bit constellation. The diagram shows three coordinate planes. The first plane (X1, Y1) has an open circle at (1, 1) and a solid dot at (-1, -1), labeled v0=1. The second plane (X2, Y2) has a solid dot at (1, 1) and an open circle at (-1, -1), labeled v1=0. The third plane shows the combined constellation with axes (X1+Y1)/2 and (X2+Y2)/2. It has open circles at (1, 1) and (-1, -1), and solid dots at (1, -1) and (-1, 1), labeled v1=0, v0=1. A small label G.993.2\_F10-11 is present. + +**Figure 10-11 – Combination of a pair of 1-bit constellations to build a 2-bit constellation** + +###### **10.3.3.2.2.2    $b = 3$** + +Figure 10-12 shows the constellation for the case $b = 3$ . + +![Figure 10-12: Constellation labels for b = 3. The diagram shows a 2D coordinate system with points labeled 0 through 7. Point 0 is at (1, 1), point 1 is at (1, -1), point 2 is at (-1, 1), point 3 is at (-1, -1), point 4 is at (-3, 1), point 5 is at (1, 3), point 6 is at (-3, -3), and point 7 is at (3, -1). The axes have tick marks at -3, -1, 1, and 3. A small label G.993.2_F10-12 is present.](5fac5866807d0c9afe95a782f8b96f63_img.jpg) + +Figure 10-12: Constellation labels for b = 3. The diagram shows a 2D coordinate system with points labeled 0 through 7. Point 0 is at (1, 1), point 1 is at (1, -1), point 2 is at (-1, 1), point 3 is at (-1, -1), point 4 is at (-3, 1), point 5 is at (1, 3), point 6 is at (-3, -3), and point 7 is at (3, -1). The axes have tick marks at -3, -1, 1, and 3. A small label G.993.2\_F10-12 is present. + +**Figure 10-12 – Constellation labels for $b = 3$** + +###### **10.3.3.2.2.3    $b > 3$** + +If $b$ is odd and greater than 3, the two MSBs of $X$ and the two MSBs of $Y$ shall be determined by the five MSBs of the $b$ bits ( $v_{b-1} v_{b-2} … v_1 v_0$ ). Let $c = (b+1)/2$ , then $X$ and $Y$ shall have the twos-complement binary representations $(X_c X_{c-1} v_{b-4} v_{b-6} … v_3 v_1 1)$ and $(Y_c Y_{c-1} v_{b-5} v_{b-7} v_{b-9} … v_2 v_0 1)$ , where $X_c$ and $Y_c$ are the sign bits of $X$ and $Y$ respectively. The relationship between $X_c, X_{c-1}, Y_c, Y_{c-1}$ , and $(v_{b-1} v_{b-2} … v_{b-5})$ shall be as shown in Table 10-3. + +**Table 10-3 – Determining the top two bits of $X$ and $Y$** + +| $v_{b-1} v_{b-2} \dots v_{b-5}$ | $X_c X_{c-1}$ | $Y_c Y_{c-1}$ | $v_{b-1} v_{b-2} \dots v_{b-5}$ | $X_c X_{c-1}$ | $Y_c Y_{c-1}$ | +|---------------------------------|---------------|---------------|---------------------------------|---------------|---------------| +| 0 0 0 0 0 | 0 0 | 0 0 | 1 0 0 0 0 | 0 1 | 0 0 | +| 0 0 0 0 1 | 0 0 | 0 0 | 1 0 0 0 1 | 0 1 | 0 0 | +| 0 0 0 1 0 | 0 0 | 0 0 | 1 0 0 1 0 | 1 0 | 0 0 | +| 0 0 0 1 1 | 0 0 | 0 0 | 1 0 0 1 1 | 1 0 | 0 0 | +| 0 0 1 0 0 | 0 0 | 1 1 | 1 0 1 0 0 | 0 0 | 0 1 | +| 0 0 1 0 1 | 0 0 | 1 1 | 1 0 1 0 1 | 0 0 | 1 0 | +| 0 0 1 1 0 | 0 0 | 1 1 | 1 0 1 1 0 | 0 0 | 0 1 | +| 0 0 1 1 1 | 0 0 | 1 1 | 1 0 1 1 1 | 0 0 | 1 0 | +| 0 1 0 0 0 | 1 1 | 0 0 | 1 1 0 0 0 | 1 1 | 0 1 | +| 0 1 0 0 1 | 1 1 | 0 0 | 1 1 0 0 1 | 1 1 | 1 0 | +| 0 1 0 1 0 | 1 1 | 0 0 | 1 1 0 1 0 | 1 1 | 0 1 | +| 0 1 0 1 1 | 1 1 | 0 0 | 1 1 0 1 1 | 1 1 | 1 0 | +| 0 1 1 0 0 | 1 1 | 1 1 | 1 1 1 0 0 | 0 1 | 1 1 | +| 0 1 1 0 1 | 1 1 | 1 1 | 1 1 1 0 1 | 0 1 | 1 1 | +| 0 1 1 1 0 | 1 1 | 1 1 | 1 1 1 1 0 | 1 0 | 1 1 | +| 0 1 1 1 1 | 1 1 | 1 1 | 1 1 1 1 1 | 1 0 | 1 1 | + +Figure 10-13 shows the constellation for the case $b = 5$ . + +![Figure 10-13: Constellation labels for b = 5. The figure shows a 2D plot of 32 constellation points arranged in a grid. The horizontal axis (X) and vertical axis (Y) both range from -5 to +5. The points are labeled with integers from 0 to 31. The labels are distributed as follows: 0 is at (0,0); 1, 3, 5, 7 are on the positive X-axis; 2, 4, 6, 8 are on the negative X-axis; 9, 11, 13, 15 are on the positive Y-axis; 10, 12, 14, 16 are on the negative Y-axis; 17, 19, 21, 23 are at the top-right corners of the grid; 18, 20, 22, 24 are at the top-left corners; 25, 27, 29, 31 are at the bottom-left corners; and 26, 28, 30, 32 are at the bottom-right corners. Tick marks on the axes are labeled at intervals of 2: -5, -3, -1, 1, 3, 5 on both axes.](7a0281fac8690d8894ef1cb92d1a7704_img.jpg) + +Figure 10-13: Constellation labels for b = 5. The figure shows a 2D plot of 32 constellation points arranged in a grid. The horizontal axis (X) and vertical axis (Y) both range from -5 to +5. The points are labeled with integers from 0 to 31. The labels are distributed as follows: 0 is at (0,0); 1, 3, 5, 7 are on the positive X-axis; 2, 4, 6, 8 are on the negative X-axis; 9, 11, 13, 15 are on the positive Y-axis; 10, 12, 14, 16 are on the negative Y-axis; 17, 19, 21, 23 are at the top-right corners of the grid; 18, 20, 22, 24 are at the top-left corners; 25, 27, 29, 31 are at the bottom-left corners; and 26, 28, 30, 32 are at the bottom-right corners. Tick marks on the axes are labeled at intervals of 2: -5, -3, -1, 1, 3, 5 on both axes. + +**Figure 10-13 – Constellation labels for $b = 5$** + +NOTE – The 7-bit constellation may be obtained from the 5-bit constellation by replacing each label $n$ by the $2 \times 2$ block of labels: + +$$\begin{matrix} 4n+1 & 4n+3 \\ 4n & 4n+2 \end{matrix}$$ + +The same procedure may then be used to construct the larger odd-bit constellations recursively. + +### **10.3.4 Constellation point scaling** + +Constellation points shall be scaled to normalize their average power, to achieve a frequency-dependent transmit PSD, and to equalize the SNR margin over the subcarriers in use. + +The scaling required to normalize the average power is dependent only on the size of the constellation. It is represented by $\chi(b_i)$ and is specified in clause 10.3.4.1. + +The gain adjuster $g_i$ is used to equalize the SNR margin over the subcarriers in use and is specified in clause 10.3.4.2. + +The PSD shaping mechanism is based on $tss_i$ coefficients and is specified in clause 10.3.4.3. The shaping by a $tss_i$ value is in addition to any shaping introduced by time-domain filters (if used). + +For subcarriers in the MEDLEY set, each constellation point $(X_i, Y_i)$ , corresponding to the complex value $X_i + jY_i$ at the output of the constellation mapper, shall be scaled by the power-normalization factor $\chi(b_i)$ , the gain adjuster $g_i$ , and a frequency-domain spectrum shaping coefficient $tss_i$ to result in a complex number $Z_i$ , defined as: + +$$Z_i = g_i \times tss_i \times \chi(b_i) \times (X_i + jY_i)$$ + +#### 10.3.4.1 Power normalization + +The values $(X, Y)$ shall be scaled such that all constellations, regardless of size, have the same average power. The required scaling, $\chi(b_i)$ , is a function only of the constellation size. + +#### 10.3.4.2 The gain adjuster + +The gain $g_i$ is intended for fine gain adjustment within a range from approximately 0.1888 to 1.33, which may be used to equalize the SNR margin for all subcarriers. The $g_i$ values in dB shall be defined as the $20 \times \log_{10}(g_i)$ , thus $g_i$ values of 0.1888 and 1.33 in linear scale correspond to $g_i$ values of $-14.5$ dB and of $+2.5$ dB, respectively. The values of $g_i$ for all MEDLEY subcarriers shall be assigned during initialization, as described in clause 12.3.5 and stored in the bits-and-gains table specified in clause 10.3.1 ( $b_i$ and $g_i$ values). The $g_i$ values may also be updated during showtime via an OLR procedure described in clauses 13 and 11.2.3.3. + +The $g_i$ settings (in the bits-and-gains table) shall comply with the following requirements: + +- If $b_i > 0$ , then $g_i$ shall be in the $[-14.5$ to $+2.5]$ (dB) range; +- If $b_i > 0$ , then the linear average of the $g_i^2$ 's in any band (as specified during the ITU-T G.994.1 handshake phase of initialization, see clause 12.3.2) shall be $\leq 1$ ; +- If $b_i = 0$ , then $g_i$ shall be equal to 0 (linear) or in the $[-14.5$ to $0]$ (dB) range; +- The gain adjustments shall be set in accordance with service priorities specified in clause 12.3.7. + +For subcarriers not in the MEDLEY set, see Table 10-4. + +##### 10.3.4.2.1 Nominal aggregate transmit power (NOMATP) + +The nominal aggregate transmit power (NOMATP) shall be computed by the following equation: + +$$\text{NOMATP} = 10 \log_{10} \Delta f + 10 \log_{10} \left( \sum_{i \in \text{MEDLEY set}} \left( 10^{\frac{\text{MREFPSD}[i]}{10}} g_i^2 \right) \right)$$ + +where $\text{MREFPSD}[i]$ and $g_i$ are, respectively, the values of $\text{MREFPSD}$ in dBm/Hz and gain (linear scale) for subcarrier $i$ from the MEDLEY set (see clause 12.3.3.2.1.3), and $\Delta f$ is the subcarrier spacing in Hz. + +The downstream NOMATP (NOMATPds) shall be computed for subcarriers from the downstream MEDLEY set (MEDLEYds). The upstream NOMATP (NOMATPus) shall be computed for subcarriers from the upstream MEDLEY set (MEDLEYus). + +The downstream maximum nominal aggregate transmit power during initialization and showtime (parameter MAXNOMATPds) is defined by the CO-MIB as specified in [ITU-T G.997.1]. The + +MAXNOMATPds settings in the CO-MIB shall not exceed the maximum downstream aggregate transmit power specified in Table 6-1. + +The upstream maximum nominal aggregate transmit power during initialization and showtime is defined by the control parameter *MAXNOMATPus*. The control parameter *MAXNOMATPus* is determined by the maximum aggregate upstream transmit power specified in Table 6-1. + +NOTE – There is no configuration parameter MAXNOMATPus defined in the CO-MIB (see Table 7-15 of [ITU-T G.997.1]). + +The $g_i$ settings at the VTU-O and VTU-R shall be such that the values of NOMATPds and NOMATPus do not exceed, respectively, the CO-MIB parameter MAXNOMATPds and the control parameter *MAXNOMATPus*. To assist the proper gain setting at the VTU-O, the MAXNOMATPds is communicated from the VTU-O to the VTU-R during the channel discovery phase. + +#### 10.3.4.3 Frequency-domain transmit spectrum shaping ( $tss_i$ ) + +The $tss_i$ are intended for frequency-domain spectrum shaping, both upstream and downstream. The $tss_i$ values are vendor discretionary and shall be in the range between 0 and 1 (linear) in steps of $\frac{1}{1024}$ . The $tss_i$ values shall be set such that the highest $tss_i$ value across all subcarriers is 1. Smaller values of $tss_i$ provide attenuation, and the value $tss_i = 0$ corresponds to no power transmitted on the particular subcarrier. If no frequency-domain spectrum shaping is applied, the $tss_i$ values shall be equal to 1 for all subcarriers. + +The $tss_i$ values in dB ( $\log\_tss_i$ ) are defined as $20 \times \log_{10}(tss_i)$ and shall be converted to linear values of $tss_i$ using the equation: + +$$tss_i = \frac{\text{Round} \left( 1024 \times 10^{\frac{\log\_tss_i}{20}} \right)}{1024}$$ + +The values of $tss_i$ for the given direction of transmission shall be determined by the transmitting VTU, and shall be defined as a set of breakpoints $\{(i_1, \log\_tss_{i1}), \dots, (i_n, \log\_tss_{in})\}$ , where $i$ is the subcarrier index. This set shall be communicated to the receiving VTU during the channel discovery phase of the initialization using O-PRM and R-PRM messages, as described in clause 12.3.3.2. Both transmitting and receiving VTUs shall derive the $tss_i$ values for subcarriers between the breakpoints using linear interpolation of the defined $\log\_tss_i$ values over the linear scale of subcarrier indexes. The receiving VTU shall assign $tss_i$ values equal to $tss_{in}$ for $i > i_n$ , and equal to $tss_{i1}$ for $i < i_1$ . + +The obtained values of $tss_i$ are relevant only for subcarriers that are actually transmitted. The receiver shall ignore the $tss_i$ values that are either received or obtained by interpolation for the subcarriers that are not used for transmission ( $Z_i=0$ , see Table 10-4). + +The combined accuracy of the linear interpolation of $\log\_tss_i$ values and of the conversion to linear $tss_i$ values shall be less than one half LSB for the 10-bit representation format of the linear $tss_i$ values. No error shall be introduced when $\log\_tss_i$ equals 0 dB or is interpolated between $\log\_tss_i$ values that equal 0 dB. + +The transmitters of the VTU-O and VTU-R, respectively, shall set the $tss_i$ values such that, prior to the gain adjustment (i.e., assuming $g_i=1$ ), the PSD of the transmit signal as measured in the reference impedance at the U interface, from the start of the training phase and for the remainder of initialization, shall not deviate from the values of MREFPSDds and MREFPSDus, communicated in O-PRM and R-PRM, respectively, by more than 1 dB (parameter "MEDLEY reference PSD", see clause 12.3.3.2). Thus, $tss_i$ settings shall take into consideration any additional spectrum shaping caused by time-domain filters and analog filters included in the transmission path between the output of the modulator and U interface. + +#### 10.3.4.4 Summary of subcarrier constellation mapping and constellation point scaling + +Table 10-4 summarizes the subcarrier constellation mapping and constellation point scaling requirements for the stages of initialization and during showtime. + +**Table 10-4 – Summary of subcarrier modulation in initialization and showtime** + +| Phase | Subcarrier index (i) | | $Z_i$ | +|----------------------------------------|-------------------------------------|----------------------------------------------------------------------|----------------------------------------------------------| +| Channel discovery (12.3.3) | $i \in \text{SUPPORTEDCARRIERS}$ | | $tss_i \times (X_i + jY_i)$ | +| | $i \notin \text{SUPPORTEDCARRIERS}$ | | 0 | +| Training (12.3.4) | $i \in \text{MEDLEY}$ | | $tss_i \times (X_i + jY_i)$ | +| | $i \notin \text{MEDLEY}$ (Note 1) | | 0 | +| Channel analysis and exchange (12.3.5) | $i \in \text{MEDLEY}$ | | $tss_i \times (X_i + jY_i)$ | +| | $i \notin \text{MEDLEY}$ | | 0 | +| Showtime | $i \in \text{MEDLEY}$ | $b_i > 0, g_i > 0$ | $g_i \times tss_i \times \chi(b_i) \times (X_i + jY_i)$ | +| | | Monitored subcarriers
( $b_i = 0, g_i > 0$ , modulated by 4-QAM) | $g_i \times tss_i \times \chi(b = 2) \times (X_i + Y_i)$ | +| | | Pilot tones
( $b_i = 0, g_i > 0$ , modulated by 4-QAM) | $g_i \times tss_i \times \chi(b = 2) \times (X_i + Y_i)$ | +| | | Others with $b_i = 0, g_i = 0$ | 0 | +| | $i \notin \text{MEDLEY}$ | $i \in \text{SUPPORTEDCARRIERS}$ , and
$i \in \text{BLACKOUT}$ | 0 | +| | | $i \in \text{SUPPORTEDCARRIERS}$ , and
$i \notin \text{BLACKOUT}$ | Vendor discretionary
(Note 2) | +| | | $i \notin \text{SUPPORTEDCARRIERS}$ | 0 | + +NOTE 1 – The O-P-TEQ and R-P-TEQ signals used during the training phase include subcarriers that are outside the MEDLEY set. See clause 12.3.4.3 for details. + +NOTE 2 – The PSD of vendor-discretionary signals on these subcarriers shall be below MREFMASK by 10 dB. + +## 10.4 Modulation + +### 10.4.1 Data subcarriers + +The subcarriers shall be indexed from $i = 0$ to $i = MSI$ , where $MSI$ is the index of the highest loaded subcarrier (i.e., the maximum index in the MEDLEY set). The values of $MSI$ may be different for upstream and downstream transmission and are denoted as $MSI_{us}$ and $MSI_{ds}$ respectively. The index of the highest loaded subcarrier ( $MSI_{us}$ or $MSI_{ds}$ ) will be restricted by the selected profile and band plan as shown in Table 6-1. Specifically, $MSI_{us}$ shall be equal to or lower than the "index of the highest supported upstream data-bearing subcarrier" (6.2.10) and $MSI_{ds}$ shall be equal to or lower than the "index of the highest supported downstream data-bearing subcarrier" (6.2.9). Transmission will take place on $NSC$ subcarriers, with $NSC_{us} \leq MSI_{us}$ and $NSC_{ds} \leq MSI_{ds}$ ; the subcarrier with index $i=0$ shall not be used. $NSC_{us} + NSC_{ds}$ shall always be less than 4096. + +The subcarriers to be used for data transport in the upstream and downstream directions (MEDLEYus and MEDLEYds sets, respectively) shall be determined during initialization, as specified in clause 12.3.3. + +NOTE – The subcarriers used for data transmission depend on channel characteristics, such as loop attenuation and noise, and on the specific requirements on the PSD of the transmit signal, such as notching of amateur radio bands, PSD reduction at low frequencies to share the loop with POTS or ISDN, and others. + +### 10.4.2 Subcarrier spacing + +Subcarrier spacing is the frequency spacing, $\Delta f$ , between the subcarriers. The subcarriers shall be centered at frequencies $f_i = i \times \Delta f$ . The subcarrier index $i$ takes the values $i = 0, 1, 2, \dots, MSI$ . Valid values of subcarrier spacing are 4.3125 kHz and 8.625 kHz, both with a tolerance of $\pm 50$ ppm. + +Subcarrier spacing is profile dependent (see Table 6-1). + +### 10.4.3 Modulation by the inverse discrete Fourier transform (IDFT) + +The IDFT is used to modulate the output of the symbol encoder onto the DMT subcarriers. It converts the $NSC$ complex values $Z_i$ (as defined in clause 10.3.4) generated by the symbol encoder (frequency domain representation) into $2N$ real values $x_n$ ( $n = 0, 1, \dots, 2N-1$ ), which is a time domain representation. The conversion shall be performed with a $2N$ point IDFT, with $N-1 \geq MSI$ , as: + +$$x_n = \sum_{i=0}^{2N-1} \exp\left(j \cdot 2 \cdot \pi \cdot \frac{n \cdot i}{2 \cdot N}\right) \cdot Z_i \quad \text{for } n = 0 \text{ to } 2N-1$$ + +The valid values of $N$ are $N = 2^{n+5}$ , where $n$ can take integer values from 0 to 7. The values of $N$ used for upstream and downstream are exchanged during initialization (see clauses 12.3.2, 12.3.3.2.1.3, and 12.3.3.2.2.3). + +For subcarrier indices $i$ that are not in the MEDLEY set and for $MSI < i < N$ , the corresponding values of $Z_i$ are not generated by the symbol encoder. These values are vendor discretionary, but shall comply with the constraints given in Table 10-4. $Z_0$ shall always be equal to zero and $Z_N$ shall always be a real value. + +In order to generate real values of $x_n$ , the input values $Z_i$ , where $i = 0, 1, \dots, N-1$ and $Z_0 = 0$ , shall be further augmented so that the vector $Z_i$ has a Hermitian symmetry: + +$$Z_i = \text{conj}(Z_{2N-i}) \quad \text{for } i = N+1 \text{ to } 2N-1$$ + +NOTE – Different values of $N$ result in different transmit signal images above the Nyquist frequency. Knowledge of how the additional $Z_i$ values are defined allows the receiver to better estimate the channel during initialization. + +### 10.4.4 Cyclic extension and windowing + +The transmit DMT symbol shall be constructed from the IDFT samples $x_n$ using the following rules. + +The last $L_{CP}$ samples of the IDFT output $x_n$ shall be prepended to the $2N$ output IDFT samples $x_n$ as the cyclic prefix (CP). The first $L_{CS}$ samples of $x_n$ shall be appended to the block of $x_n + L_{CP}$ samples as the cyclic suffix (CS). The first $\beta$ samples of the cyclic prefix and last $\beta$ samples of the cyclic suffix shall be used for shaping the envelope of the transmitted signal (windowing). The values of the window samples are vendor discretionary. The maximum value of $\beta$ shall be $\min(N/16, 255)$ . The windowed parts ( $\beta$ samples) of consecutive symbols shall overlap and be added to one another. + +Figure 10-14 summarizes all of the operations that shall be performed by the transmitter to construct the DMT symbol. + +The cyclic extension (CE) length is defined as $L_{CE} = L_{CP} + L_{CS} - \beta$ . The values $L_{CP}$ , $L_{CS}$ and $\beta$ shall be set in order to satisfy the equation $L_{CE} = (L_{CP} + L_{CS} - \beta) = m \times N/32$ , where valid values of $m$ are integers between 2 and 16, inclusive. Support for the value of $m = 5$ is mandatory. In all cases, the following relations shall hold: $\beta < L_{CP}$ and $\beta < L_{CS}$ . + +NOTE – Partitioning between the CS and CP is vendor discretionary. The specific settings of the CE and CP are exchanged during initialization. + +![Diagram illustrating the cyclic extension, windowing, and overlap of DMT symbols. It shows two consecutive DMT symbols, 's' and 's+1'. Symbol 's' has a total length of 2N samples, with a cyclic prefix (CP) of length L_CP and a cyclic suffix (CS) of length L_CS. A window of length beta is applied to the beginning and end of the symbol. The overlap between the end of symbol 's' and the start of symbol 's+1' is shown, with the total duration of one symbol period being 2N + L_CP + L_CS - beta samples. The diagram includes labels for L_CP, L_CS, beta, 2N samples, and the total symbol duration. A reference code G.993.2_F10-14 is present in the bottom right.](df803281854ce2cbde7019b5aeefd8cd_img.jpg) + +Diagram illustrating the cyclic extension, windowing, and overlap of DMT symbols. It shows two consecutive DMT symbols, 's' and 's+1'. Symbol 's' has a total length of 2N samples, with a cyclic prefix (CP) of length L\_CP and a cyclic suffix (CS) of length L\_CS. A window of length beta is applied to the beginning and end of the symbol. The overlap between the end of symbol 's' and the start of symbol 's+1' is shown, with the total duration of one symbol period being 2N + L\_CP + L\_CS - beta samples. The diagram includes labels for L\_CP, L\_CS, beta, 2N samples, and the total symbol duration. A reference code G.993.2\_F10-14 is present in the bottom right. + +**Figure 10-14 – Cyclic extension, windowing and overlap of DMT symbols** + +For a given setting of the CE length and window length $\beta$ , the DMT symbols will be transmitted at a symbol rate equal to: + +$$f_{DMT} = \frac{2N \times \Delta f}{2N + L_{CP} + L_{CS} - \beta} = \frac{2N \times \Delta f}{2N + L_{CE}}$$ + +If the CE length corresponds to $m = 5$ , this results in symbol rates of 4 ksymbols/s for $\Delta f = 4.3125$ kHz and 8 ksymbols/s for $\Delta f = 8.625$ kHz, independent of the sampling rate used. + +The data symbol rate is equal to: + +$$f_s = \frac{2N \times \Delta f}{2N + L_{CP} + L_{CS} - \beta} \times \frac{256}{257}$$ + +The equivalent 4k DMT symbol length (denoted as $T_{4k}$ ) is defined as: + +$$T_{4k} = \frac{1}{f_{DMT}} \quad \text{for } \Delta f = 4.3125 \text{ kHz, and}$$ + +$$T_{4k} = \frac{2}{f_{DMT}} \quad \text{for } \Delta f = 8.625 \text{ kHz.}$$ + +If the CE length corresponds to $m = 5$ , this results in an equivalent 4k DMT symbol length of 250 $\mu\text{s}$ , independent of the subcarrier spacing and sampling rate used. + +### 10.4.5 Synchronization + +#### 10.4.5.1 Pilot tones + +The VTU-R may select one or more subcarriers to use for timing recovery, called "pilot tones". Pilot tones are selected separately for initialization and showtime. + +*Pilot tones during initialization:* The VTU-R may select initialization pilot tones by indicating its selection of pilot tones in R-MSG 1 (see clause 12.3.3.2.2.1). Initialization pilot tones are used for initialization signals O-P-PILOT1, O-P-PILOT2, O-P-PILOT3 and O-P-ECT as specified in clauses 12.3.3 and 12.3.4. The total number of initialization pilot tones shall not exceed 16. + +*Pilot tones during showtime:* The VTU-R may select showtime pilot tones by indicating its selection of pilot tones in R-PMD (see clause 12.3.5.2.2.4). The VTU-O shall transmit on the selected subcarriers the value of 00 using 4-QAM modulation during every data symbol of showtime. The constellation point scaling for the pilot tone(s) shall follow the same rules as for data carrying subcarriers described in clause 10.3.4. The total number of pilot tones shall not exceed 16. Pilot tones are not transmitted on sync symbols (see clause 10.5.1). + +#### 10.4.5.2 VTU-R timing + +The VTU-R shall perform loop timing (see clause 3.30). + +#### 10.4.5.3 Timing advance + +The VTU-R shall be capable of implementing a timing offset between transmit and receive DMT symbols, called timing advance (TA). It shall set the TX symbol TA reference point prior to the RX symbol TA reference point by the value of TA, see Figure 10-15. For the purpose of implementing TA, the TX symbol TA reference point is $\text{floor}(\beta_{us}/2)$ samples after the first sample of the cyclic prefix. Similarly, for the purpose of implementing TA, the RX symbol TA reference point is $\text{floor}(\beta_{ds}/2)$ samples after the estimated first sample of the cyclic prefix. The estimation of the first sample of the received symbol is vendor discretionary and may depend on loop conditions. However, the VTU-R should make its best effort to meet the TA at the U interface. The TA shall be calculated and set during initialization, as specified in clauses 12.3.3 and 12.3.4. + +If the value of TA is exactly equal to the propagation delay from the VTU-O to the VTU-R, it will force the VTU-O and VTU-R to start transmission of DMT symbols in opposite directions simultaneously (i.e., the DMT symbols in the downstream and upstream transmission directions start at the same absolute time). This results in orthogonality between transmitted and received DMT symbols when the minimum value of CE length is used. + +NOTE – To obtain the desired orthogonality between transmit and receive signals with the minimum value of CE length, the value of TA should apply at the U interface. + +![Figure 10-15 – Illustration of TA (VTU-R). The diagram shows two waveforms: an RX Symbol (top) and a TX Symbol (bottom). The RX Symbol has a cyclic prefix of length beta_ds and a data portion of length beta_ds. Its TA reference point is marked by a dashed vertical line at beta_ds/2 samples after the start of the cyclic prefix. The TX Symbol has a cyclic prefix of length beta_us and a data portion of length beta_us. Its TA reference point is marked by a dashed vertical line at beta_us/2 samples after the start of the cyclic prefix. The Timing Advance (TA) is the time interval between the TX symbol TA reference point and the RX symbol TA reference point. The diagram is labeled G.993.2_F10-15.](c2f5e14ca0ed0f7944c7606451f67d85_img.jpg) + +Figure 10-15 – Illustration of TA (VTU-R). The diagram shows two waveforms: an RX Symbol (top) and a TX Symbol (bottom). The RX Symbol has a cyclic prefix of length beta\_ds and a data portion of length beta\_ds. Its TA reference point is marked by a dashed vertical line at beta\_ds/2 samples after the start of the cyclic prefix. The TX Symbol has a cyclic prefix of length beta\_us and a data portion of length beta\_us. Its TA reference point is marked by a dashed vertical line at beta\_us/2 samples after the start of the cyclic prefix. The Timing Advance (TA) is the time interval between the TX symbol TA reference point and the RX symbol TA reference point. The diagram is labeled G.993.2\_F10-15. + +Figure 10-15 – Illustration of TA (VTU-R) + +#### 10.4.5.4 Synchronous mode + +Support of synchronous mode is optional. In synchronous mode, the out-of-band near-end crosstalk (NEXT) generated by the VDSL2 systems operating in synchronous mode will be nearly orthogonal to the VDSL2 signals received by other VTUs operating in synchronous mode. Therefore, the NEXT will not significantly degrade the SNR on other lines in synchronous mode. + +In synchronous mode, all VTU-Os shall use the same subcarrier spacing and symbol rate, and shall start transmission of DMT symbols at the same time on all of the lines in the synchronized group. The transmit symbol clocks shall be phase-synchronous at all VTU-Os with a 1 $\mu\text{s}$ maximum phase error tolerance. + +In synchronous mode, all VTUs shall use the same value of CE length (see clause 10.4.4). The CE length used for all lines in the synchronized group should have values appropriate for the line in the group that has the largest propagation delay. + +## 10.5 Symbol encoder for sync symbol + +### 10.5.1 Constellation mapper for sync symbol + +Each MEDLEY subcarrier of the sync symbol in either transmission direction (MEDLEYds or MEDLEYus; see clauses 12.3.3.2.1.3 and 12.3.3.2.2.3) shall be modulated by two bits from the sync frame (which will be either 00 or 11 for all MEDLEY subcarriers) using the 4-QAM constellation defined in clause 10.3.3.2.1. The constellation points on these subcarriers shall then be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Pilot tones (as specified in clause 10.4.5.1) are not transmitted on sync symbols. + +NOTE – The first five and last five symbols of initialization signals O-P-SYNCHRO and R-P-SYNCHRO are identical to a sync symbol modulating a sync frame of all ONES. The middle five symbols of O-P-SYNCHRO and R-P-SYNCHRO are identical to a sync symbol modulating a sync frame of all ZEROS. + +An inversion of the bits in the sync frame (i.e., from all ONES to all ZEROS and vice versa) shall be used to signal on-line reconfiguration timing during showtime, as described in clause 10.5.3. + +For the subcarriers in the SUPPORTEDCARRIERS set that are not in the MEDLEY set and are not in the BLACKOUT set, the constellation mapper may select a vendor-discretionary $(X, Y)$ point, which may also change from one sync symbol to another (see Table 10-4). + +### 10.5.2 Constellation point scaling for sync symbol + +The $\chi(b_i)$ , $g_i$ and $tss_i$ values shall be applied to the sync symbol in the same way as they are applied to data symbols in showtime (see clause 10.3.4). + +### 10.5.3 On-line reconfiguration + +The transmitter inserts a sync symbol every 257 symbols, as defined in clause 10.2. Therefore, a sync symbol shall be transmitted after every 256 data symbols. + +To signal on-line reconfiguration timing (see clause 13.3), the responding VTU shall send a Syncflag (see clause 3.64). + +After the transmission of a Syncflag, the sync frame modulated onto subsequent sync symbols shall remain the same (i.e., either all ONES or all ZEROS) until timing for the next on-line reconfiguration needs to be signalled. + +At the beginning of showtime, the first sync symbol transmitted shall be modulated by a sync frame of all ones. + +## 10.6 Symbol encoder for initialization + +Encoding of DMT symbols transmitted during the different phases of initialization is specified in clauses 12.3.3.3, 12.3.4.3, and 12.3.5.3. The values of $X$ and $Y$ of the 4-QAM constellation points during initialization shall be as shown in the constellation diagram of Figure 10-9. These values shall be scaled such that at the output of the constellation mapper the constellation represents the root mean square (rms) energy of a subcarrier transmitted at the relevant PSD level. The applicable PSD levels are specified in clauses 12.3.3.3, 12.3.4.3 and 12.3.5.3. + +# 11 Operation and maintenance (OAM) + +## 11.1 OAM functional model + +The operations, administration and maintenance (OAM) reference model of a VDSL2 link, as shown in Figure 11-1, contains OAM entities intended to manage the following transmission entities: + +- *VDSL2 Line entity*: The physical transmission entity, which includes the PMD and PMS-TC sublayers; +- *VDSL2 Path entity*: The transport protocol path, which includes the TPS-TC sublayer; and +- *VDSL2 System entity*: The application path, which includes all relevant layers above the TPS-TC. + +![Figure 11-1 – OAM reference model diagram showing the interaction between NMS, VTU-O, and VTU-R across various management layers and interfaces.](863f4c0af0db9c27290338ff76162c06_img.jpg) + +The diagram illustrates the OAM reference model for a VDSL2 link between a VTU-O (left) and a VTU-R (right). At the top, an NMS (Network Management System) is connected to the VTU-O's System management block. The VTU-O and VTU-R are shown as stacked boxes representing different layers. The layers and their management blocks are: System management (top), VTU-O/VTU-R (middle), TPS-TC management, PMS-TC management, and PMD management (bottom). Horizontal arrows indicate OAM data flows between corresponding management blocks in the VTU-O and VTU-R. These flows are labeled: 'System-related OAM data' between System management blocks, 'Path-related OAM data' between TPS-TC management blocks, 'Line-related OAM data' between PMS-TC management blocks, and 'Line-related OAM data (initialization)' between PMD management blocks. Vertical dashed lines separate the VTU-O and VTU-R from the NMS and from each other, labeled as $\gamma$ -interface, $\alpha(\beta)$ -interface, $I$ -interface, and $U2$ -interface. On the far left, vertical double-headed arrows categorize the layers into 'System-related entity', 'Path-related entity', and 'Line-related entity'. Adjacent to these are the 'Application layer', 'TPS-TC sublayer', 'PMS-TC sublayer', and 'PMD sublayer'. + +Figure 11-1 – OAM reference model diagram showing the interaction between NMS, VTU-O, and VTU-R across various management layers and interfaces. + +Figure 11-1 – OAM reference model + +The peer OAM entities at the VTU-O and VTU-R exchange management data over OAM-dedicated communication channels arranged over the mentioned transmission entities. The NMS, located at the VTU-O, controls the OAM entities at both VTUs, and collects management data from all OAM entities. The OAM flows across the communication channels convey path-related and line-related primitives and parameters, configuration setups, and maintenance commands and acknowledgments. + +The functional model of the OAM operation and communication over the VDSL2 link is presented in Figure 11-2. The external OAM interface adapter (EIA) provides the interface to the NMS (Q interface), and the interface with the MIB. The MIB contains all of the management information related to the VDSL2 link. It may be implemented to serve an individual VDSL2 line or to be shared between several lines. + +The VME collects the OAM data from and delivers it to all of the VTU transmission entities, thus providing all internal OAM functions for the VTU. It also supports all interactive management functions between the VTU-O and the VTU-R using two OAM-dedicated communication channels: + +- Indicator bits (IB) channel; and +- Embedded operations channel (eoc). + +The VME interfaces with the EIA, thus exchanging management data with the MIB. The VME functionality is specified in clause 11.2.1. The EIA functions concerning operation with the external interfaces (Ext\_OAM\_R interface, Q interface), with the MIB, and the interface between VME and EIA are beyond the scope of this Recommendation. + +![Figure 11-2 – Functional model of OAM of the VDSL2 link. The diagram shows two symmetric sides, VTU-R (left) and VTU-O (right), connected by a physical link (U-R and U-O). Each side consists of a stack of layers: PMD, PMS-TC, MPS-TC, and VME. The VME is connected to an EIA, which is connected to an MIB. The EIA also connects to external interfaces: Ext_OAM_R interface on the VTU-R side and Q interface (SNMP) on the VTU-O side. Management data flows between the VME and the MPS-TC via IB and eoc channels. The eoc channel is labeled 'OAM Data, commands'. The physical link between the PMD layers is labeled 'U-R' and 'U-O'. The diagram is labeled G.993.2_F11-2.](5ec3284657e4df0df3653dd61d0ecd13_img.jpg) + +MIB Management information base +VME VDSL management entity +EIA External interface adapter + +G.993.2\_F11-2 + +Figure 11-2 – Functional model of OAM of the VDSL2 link. The diagram shows two symmetric sides, VTU-R (left) and VTU-O (right), connected by a physical link (U-R and U-O). Each side consists of a stack of layers: PMD, PMS-TC, MPS-TC, and VME. The VME is connected to an EIA, which is connected to an MIB. The EIA also connects to external interfaces: Ext\_OAM\_R interface on the VTU-R side and Q interface (SNMP) on the VTU-O side. Management data flows between the VME and the MPS-TC via IB and eoc channels. The eoc channel is labeled 'OAM Data, commands'. The physical link between the PMD layers is labeled 'U-R' and 'U-O'. The diagram is labeled G.993.2\_F11-2. + +**Figure 11-2 – Functional model of OAM of the VDSL2 link** + +To communicate management data, the VME uses eoc messages (specified in clause 11.2.3) and IB (specified in clause 11.2.4). The eoc messages and IB form a complete set of management data exchanged between the VTU-O and VTU-R, which includes the management data from all data-transmission sublayers of the VTU and the management data incoming from the EIA, including messages sent to the VTU-R. The latter are referred to in [ITU-T G.997.1] and in clause 11.2.3 as a "clear eoc". The interfaces between the VME and the TC sublayer for both OAM communication channels are functional and are defined in clause 8.2.2 (MPS-TC) and in clause 9.5.2.2 (IB). The eoc communication protocol is defined in clause 11.2.2. + +The VME sends eoc messages via the $\gamma_m$ interface to the management TPS-TC (MPS-TC) defined in clause 8.2.2. The MPS-TC encapsulates eoc messages into HDLC frames to transfer them over the VDSL2 link using the PMS-TC overhead channel (the MSG field of the OH frame specified in + +clause 9.5.2.2). At the receive side, the MPS-TC extracts the received eoc messages from HDLC frames and submits them to the VME via the $\gamma_m$ interface. + +For the IB transport no TPS-TC is needed; the IB are directly mapped to the IB field of the OH frame as specified in clause 9.5.2.2. + +### **11.1.1 OAM communication channels** + +#### **11.1.1.1 IB channel** + +The IB channel is shared for communication between the peer OAM entities of the PMD, PMS-TC and TPS-TC. It is intended to transfer time-sensitive primitives (those requiring an immediate action) from the far end. The IB channel operates in a unidirectional mode, i.e., the upstream and downstream directions of the IB channel operate independently, and there are no acknowledgements or retransmissions in the protocol. The IB are specified in clause 11.2.4. + +#### **11.1.1.2 eoc** + +The eoc is shared for communication between the peer OAM entities of the PMD, PMS-TC, TPS-TC and VME (system-related OAM data, such as power-related primitives). The eoc is mostly intended to exchange management data that is not time critical. It is used to transport clear eoc messages and MIB elements specified in [ITU-T G.997.1], to set and query parameters, and to invoke management procedures at the far-end VTU. The eoc provides exchange of the PMD, PMS-TC, TPS-TC and system-related primitives, performance parameters, test parameters, configuration parameters and maintenance commands. The eoc communication protocol is specified in clause 11.2.2. + +## **11.2 VDSL2 management entity (VME)** + +### **11.2.1 VME functionality** + +The VME provides all necessary management functions specified in [ITU-T G.997.1] to communicate with the MIB and with the NMS via the EIA. It shall also manage the OAM communication channels, and support all internal management functions of the VTU, including: + +- performance monitoring; +- performance management; +- configuration management; and +- fault management. + +The VME shall provide all of the functionality to communicate the management data between the VTU-O and the VTU-R. Specifically, the VME shall: + +- originate eoc messages and IB to communicate management data; +- assign priority levels for eoc messages to share the overhead messaging channel; and +- maintain the protocol of eoc message exchange (re-send messages, abandon certain tasks, etc.). + +The VME-O shall update and store the set of near-end test parameters (the ones that can be updated during Showtime) within 10 seconds after receiving the request to do so from the NMS. + +The VME-O shall update and store the set of far-end test parameters (the ones that can be updated during Showtime) within 30 seconds after receiving the request to do so from the NMS. + +### **11.2.2 eoc transmission protocol** + +A VTU invokes eoc communication with the VTU at the other end of the link by sending an eoc command message. The responding VTU, acting as a slave, shall acknowledge a command it has received correctly by sending a response, unless one is not required for the particular command type. + +Furthermore, it shall perform the requested management function. Both VTUs shall be capable of sending eoc commands and responding to received eoc commands. The same eoc protocol format shall be used in both transmission directions. To send commands and responses over the line, the VME originates eoc messages. Each eoc message is a command, a command segment, a response, or a response segment. The VME sends each eoc message to the MPS-TC. + +The MPS-TC encapsulates all incoming messages into HDLC format, as specified in clause 8.2.3. The length of any eoc message shall be less than or equal to 1024 octets, as described in clause 11.2.3.1. + +Each command and the corresponding response are associated with a priority level specified in clause 11.2.3.1. To maintain priorities of eoc commands when sent over the link, the VME shall send messages to the MPS-TC via the $\gamma_m$ interface in accordance with the priority levels of the commands (responses) carried by these messages, as specified in Table 11-1. + +**Table 11-1 – eoc message priority levels** + +| Priority level | Associated time-out value | eoc command (response) | +|----------------|---------------------------|---------------------------------------| +| High | 400 ms | Table 11-2, UTC (see clause 11.2.3.2) | +| Near High | For further study | Table 11-3 | +| Normal | 800 ms | Table 11-4 | +| Low | 1 s | Table 11-5 | + +The VME shall send the eoc command only once and wait for a response, if one is required. No more than one command of each priority level shall be awaiting a response at any time. Upon reception of the response, a new command of the same priority level may be sent. If the command is segmented, all the segments of the command shall be sent and responses received before the next command is sent. + +Accordingly, the VME shall send the message carrying a command or a segment of a command only once and wait for a response message. Upon reception of the response message, a new message may be sent. If a response to a particular message is not received within a specified time period (see Table 11-1), or is received incorrectly, a time-out occurs. After a time-out, the VME shall re-send the message up until REINIT\_TIME\_THRESHOLD seconds from the first time-out after which it shall abandon the message. + +From all of the messages available for sending at any time, the VME shall always send the message with highest priority first. If a message with a higher priority than the one that is currently being sent becomes available for sending, the VME may abort sending the lower priority message (by setting the *Tx\_Stop* signal, as specified in clause 8.2.4.1). The VME shall re-send the aborted message as the priority rule allows (i.e., when its priority level is the highest among all messages available for sending). + +Messages of different priority have different time-out durations, as shown in Table 11-1, except for messages for which a response is not required and hence no timeout period is applicable. Time-outs shall be calculated from the instant the MPS-TC sends the last octet of the message until the instant the VME receives the first octet of the response message. Accordingly, the time-out timer shall be started by the *Sent* signal. If the VME detects an *Rx\_RF* signal and a corresponding *Rx\_PrF* signal within the relevant time-out value specified in Table 11-1, it shall set a time stamp for the preliminary arrival time of the expected response message, and then wait for the *Rx\_Enbl* signal; otherwise the VME shall time-out for the expected response. + +If the VME detects the *Rx\_Enbl* signal in $\leq 300$ ms after *Rx\_RF* and *Rx\_PrF* signals are set, the response message is considered to be received; otherwise, the VME shall consider the received *Rx\_RF* and *Rx\_PrF* signals as false, and shall delete the time stamp and wait for the next *Rx\_RF* and *Rx\_PrF* + +signals within the rest of the time-out value specified in Table 11-1. + +The receiver uses the assigned value specified in clause 11.2.3.2 to determine the type and priority of the received eoc command (response). + +### 11.2.3 eoc commands and responses + +#### 11.2.3.1 General + +The first octet of a command (response) specifies the type of command (response). The second octet specifies the name of the command (response) for the specified type. Other octets carry the management data associated with the command (response). + +The data values to be sent shall be mapped such that the LSB of data is mapped to the LSB of the corresponding octet of the command (response). Data values containing more than one octet shall be mapped with higher order octets preceding lower order octets. A vector of data values shall be mapped in order of the index, from the lowest index value to the highest. + +If a specific command (response) is longer than 1024 octets, the VME shall segment it as specified in clause 11.2.3.3 so that the length of the eoc messages sent is shorter than $P$ octets. The maximum length $P$ of the message shall be based on the assigned message overhead data rate in the relevant transmission direction using the following equation: + +$$P \leq \min (1024, 33 \times msg_p) \text{ octets}$$ + +where: + +$msg_p$ = message overhead data rate for latency path $p$ in kbit/s (specified in clause 9.5.4). + +NOTE – With the defined value of $P$ , the transmission time of any eoc message will not exceed 270 ms (including 3% loss due to HDLC overhead and stuffing). This ensures that in all regular cases the VME will not be forced to stop sending a low-priority message in order to comply with the time-out requirements presented in Table 11-1. The VME should avoid long commands and responses. + +#### 11.2.3.2 Command and response types + +With the exception of control parameter read, which is for further study, the VTU shall support all mandatory eoc command and response types specified in Table 11-2 (high priority commands), Table 11-3 (near high priority commands), Table 11-4 (normal priority commands) and Table 11-5 (low priority commands), and their associated commands and responses specified in clauses 11.2.3.3 to 11.2.3.11, inclusive. The VTU should reply with Unable-To-Comply (UTC) response on the optional commands that the VTU cannot recognize the assigned value for the command type. The UTC response shall include two octets: the first octet of the UTC shall be the same as the first octet of the received command, and the second octet shall be FF16. The UTC is a high priority response. + +NOTE – If the UTC response is not supported, the command will time out. This would reduce the efficiency of the eoc. + +**Table 11-2 – High priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | Support | +|---------------------------------------------------------|-----------------------------------------------------------------|-------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------| +| On-line reconfiguration (OLR)
0000 0001 2 | From the receiver of either VTU to the transmitter of the other | All the necessary PMD and PMS-TC control parameter values for the new configuration | Includes either a line signal marking the instant of re-configuration (Syncflag), or an OLR intermediate acknowledge (for segmented command), or an OLR command to defer or reject the proposed reconfiguration | See Table 11-6 | +| Power Management
0000 0111 2 | From either VTU to the other | High priority LPM commands defined in Annex E of [ITU-T G.998.4] | An acknowledgement or reject of high priority LPM command as defined in Annex E of [ITU-T G.998.4] | Optional | + +**Table 11-3 – Near high priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | Support | +|-----------------------------------------------------|-----------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------|----------------| +| Frequency synchronization
0101 0000 2 | From VTU-O to VTU-R | The ToD phase difference value to run frequency synchronization: the ns_counter value of the RTC-O mod 125000 ns divided by 2, which shall be represented by a 16-bit value. | No response needed | Optional | + +**Table 11-4 – Normal priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | Support | +|----------------------------------------|-----------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------|----------------| +| Diagnostic
0100 0001 2 | From VTU-O to VTU-R | Request to run the self-test, or to update test parameters, or to start and stop transmission of corrupt CRC, or to start and stop reception of corrupt CRC | Acknowledgment | Mandatory | +| | From VTU-R to VTU-O | Request to update test parameters | Acknowledgment | Mandatory | + +**Table 11-4 – Normal priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | Support | +|-------------------------------------------------------|------------------------------|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------| +| Time
0100 0010 2 | From VTU-O to VTU-R | Set or read out the time | Acknowledgment of the set time command, or a response including the time value | Mandatory | +| Inventory
0100 0011 2 | From either VTU to the other | Identification request, auxiliary inventory information request, and self-test results request | Includes the VTU equipment ID auxiliary inventory information, and self-test results | Mandatory | +| Management counter read
0000 0101 2 | From either VTU to the other | Request to read the counters | Includes all counter values | Mandatory | +| Clear eoc
0000 1000 2 | From either VTU to the other | Clear eoc command as defined in [ITU-T G.997.1] | Acknowledgment | Mandatory | +| Power Management
0000 0111 2 | From either VTU to the other | Proposed new power state, or normal priority LPM commands defined in Annex E of [ITU-T G.998.4] | An acknowledgement to either reject or grant the new power state, or acknowledgement or reject of normal priority LPM command as defined in Annex E of [ITU-T G.998.4] | Mandatory | +| Non-standard facility (NSF)
0011 1111 2 | From either VTU to the other | Non-standard identification field followed by vendor proprietary content | An acknowledgment or a negative acknowledgment indicating that the non-standard identification field is not recognized | Mandatory | +| Control parameter read
0000 0100 2 | From either VTU to the other | For further study | For further study | Mandatory | +| Time synchronization
0101 0001 2 | From VTU-O to VTU-R | Includes the time stamps obtained by VTU-O to run time synchronization | Includes either the corresponding time stamp values of events $t_2$ and $t_3$ to accept the time synchronization (ACK) or a reject of the time synchronization command with a reason code | Optional | +| SAVN-Update
1010 0001 2 | From VTU-O to VTU-R | Request to update the showtime adaptive virtual noise (SAVN) | Acknowledgment | Optional | + +**Table 11-5 – Low priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | Support | +|--------------------------------------------------------------------|------------------------------|------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------|----------------------------| +| PMD test parameter read
1000 0001 2 | From either VTU to the other | The identification of test parameters for single read, or for multiple read, or for block read | Includes the requested test parameter values or a negative acknowledgment | See Tables 11-26 and 11-27 | +| Impulse noise monitoring (INM) facility
1000 1001 2 | From VTU-O to VTU-R | Set or readout the INM data | An acknowledgment of the INM facility set command, or a response including the INM data | Optional | +| Non-standard facility (NSF) low priority
1011 1111 2 | From either VTU to the other | Non-standard identification field followed by vendor proprietary content | An acknowledgment or a negative acknowledgment indicating that the non-standard identification field is not recognized | Mandatory | +| Data gathering
1100 1100 2 | From VTU-O to VTU-R | Configure data gathering or request a number of data gathering records | ACK/NACK the data gathering configuration or transfer data gathering records | Optional | + +#### 11.2.3.3 On-line reconfiguration (OLR) commands and responses + +The VTU shall be capable of sending and receiving the OLR commands and responses listed in Tables 11-6 and 11-7, respectively, for the supported type(s) of OLR (see clause 13.1). Any OLR command specified in Table 11-6 may be initiated by either VTU. The responding VTU may either reject the initiator's request using responses listed in Table 11-7 with reason codes listed in Table 11-8, or positively acknowledge the initiator's request by transmitting a time marker for the reconfiguration. The time marker shall be communicated by transmission of a Syncflag (see clause 10.5.3). Changes may be requested concurrently by both VTUs; each transaction shall follow the procedure described in this clause. + +The first octet of all OLR commands and responses shall be the assigned value for the OLR command type, as shown in Table 11-2. The remaining octets shall be as shown in Table 11-6 (for commands) and in Tables 11-7 and 11-8 (for responses). The octets of the OLR commands and responses shall be sent over the link as described in clause 11.2.3.1. + +The list of parameters for any command in Table 11-6 shall be selected such that the length of the eoc message in octets (prior to HDLC encapsulation) does not exceed the maximum length *P* specified in clause 11.2.3.1. If more parameters are to be re-configured simultaneously, the initiator shall segment the Request command to meet the maximum message size. The number of segments shall not exceed 64. The multi-segment transmission is supported by the segment code (SC) octet in the Request command and by the intermediate acknowledge (IACK) octet in the response. The responding VTU shall send an IACK response after every intermediate segment has been received. After all segments have been received, the responding VTU shall send the Defer or Reject response with a reason code if the request cannot be processed, or send the time marker (Syncflag, see clause 10.5.3) to implement the request. The requesting VTU shall not send the next segment until it receives the IACK for the current segment. If an IACK for an intermediate segment is not received before the time-out, the requesting VTU may either re-send it or abandon the request. The responding VTU shall consider the OLR command abandoned if no more valid segments are received within 1 second of the last segment. + +The two MSBs of the SC shall be set to 002 for intermediate segments and set to 112 for the last segment. The 6 LSBs shall contain the serial number of the segment starting from 0000002. The SC octet of an IACK shall be the same as the SC octet of the acknowledged segment. + +**Table 11-6 – OLR commands sent by the initiating VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-------------------------------------|----------------------------------------------|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------| +| Request Type 1 | $5 + 4 \times N_f$
( $N_f \leq 128$ ) | 2 | 04 16 (Note 1) | Mandatory | +| | | 3 to 4 | 2 octets for the number of subcarriers $N_f$ to be modified | | +| | | 5 to $4 + 4 \times N_f$ | $4 \times N_f$ octets describing the subcarrier parameter field for each subcarrier | | +| | | $5 + 4 \times N_f$ | 1 octet for SC | | +| Request Type 2 | For further study | 2 | 05 16 (Note 1) | For further study | +| | | All others | Reserved by ITU-T | | +| Request Type 3
(SRA)
(Note 6) | $5 + 7 N_{LP} + 4 N_f$
( $N_f \leq 128$ ) | 2 | 06 16 (Note 1) | Optional | +| | | 3 to $2 + 2 N_{LP}$ | $2 \times N_{LP}$ octets containing the new $L_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2 and 3) | | +| | | $3 + 2 N_{LP}$ to $2 + 4 N_{LP}$ | $2 \times N_{LP}$ octets containing the new $D_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Note 4) | | +| | | $3 + 4 N_{LP}$ to $2 + 5 N_{LP}$ | $N_{LP}$ octets containing the new $T_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2, 3, 5) | | +| | | $3 + 5 N_{LP}$ to $2 + 6 N_{LP}$ | $N_{LP}$ octets containing the new $G_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2, 3, 5) | | +| | | $3 + 6 N_{LP}$ to $2 + 7 N_{LP}$ | $N_{LP}$ octets containing the new $B_{po}$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2, 3, 5) | | +| | | $3 + 7 N_{LP}$ to $4 + 7 N_{LP}$ | 2 octets for the number of subcarriers $N_f$ to be modified | | +| | | $5 + 7 N_{LP}$ to $4 + 7 N_{LP} + 4 N_f$ | $4 N_f$ octets describing the subcarrier parameter field for each subcarrier | | +| | | $5 + 7 N_{LP} + 4 N_f$ | 1 octet for SC | | + +**Table 11-6 – OLR commands sent by the initiating VTU** + +| Name | Length (octets) | Octet number | Content | | Support | | +|------------------------------|-------------------|--------------------------------|----------------------------|------------------------|----------|--| +| Request Type 4 (SOS) | $N_{TG}/2+11$ | 2 | 07 16 (Note 1) | | Optional | | +| | | 3 | Message ID | | | | +| | | 4 to $N_{TG}/2+3$ | $\Delta b(2)$ | $\Delta b(1)$ | | | +| | | | $\Delta b(4)$ | $\Delta b(3)$ | | | +| | | | ⋮ | | | | +| | | | $\Delta b(N_{TG})$ | $\Delta b(N_{TG} - 1)$ | | | +| | | $N_{TG}/2+4$ to $N_{TG}/2+5$ | New value for $L_0$ | | | | +| | | $N_{TG}/2+6$ to $N_{TG}/2+7$ | New value for $L_1$ | | | | +| | | $N_{TG}/2+8$ to $N_{TG}/2+9$ | New value for $D_0$ | | | | +| | | $N_{TG}/2+10$ to $N_{TG}/2+11$ | New value for $D_1$ | | | | +| Request Type 5 (SRA/G.998.4) | See ITU-T G.998.4 | 2 | 08 16 (Note 1) | | Optional | | +| | | All others | Reserved for ITU-T G.998.4 | | | | +| Request Type 6 (SOS/G.998.4) | See ITU-T G.998.4 | 2 | 09 16 (Note 1) | | Optional | | +| | | All others | Reserved for ITU-T G.998.4 | | | | + +NOTE 1 – All other values for octet number 2 are reserved by ITU-T. +NOTE 2 – For this command, any change in $L_p$ , $T_p$ , $G_p$ , and $B_{p0}$ values shall be such that the length of the MDF (as defined in Table 9-8) remains unchanged for all active latency paths. +NOTE 3 – To keep the $msg_p$ value within its valid range for relatively large changes of $L_p$ , it may be necessary to change all of the $T_p$ , $G_p$ , and $B_{p0}$ values. +NOTE 4 – If a change of $D_p$ is not supported, the value of this parameter shall be identical to that currently used. +NOTE 5 – If a change of $T_p$ , $G_p$ and $B_{p0}$ is not supported, the values of these parameters shall be identical to those currently used. +NOTE 6 – When $N_{LP} = 2$ , the octets associated with latency path 0 are sent first. + +The message ID identifies an SOS request. The message ID shall be an 8 bit wrap-around counter. The initial value of the message ID shall be set to 0 for the first SOS request after entering Showtime. When the SOS message is repeated, the same message ID shall be maintained for as long as the same request is sent. The next SOS request shall use a message ID that is incremented by 1. + +The parameter $N_{TG}$ is the number of SOS tone groups as specified for SOS in the O/R-PMS messages (see Table 12-56, Table 12-64). + +$\Delta b(k)$ is the bit loading reduction in SOS tone group # $k$ . These values shall be coded as 4-bit unsigned integers. The number of SOS tone groups shall be derived from the information exchanged in O-PMS and R-PMS. If that number is odd, the most significant four bits in byte # $N_{TG}/2+3$ shall be set to zero at the transmitter and ignored by the receiver. + +An SOS request may be repeated before the SOS request time-out has expired. It is up to the VTU that receives the request to recognize that this is the same SOS request. Once its transmitter has acknowledged a request with given message ID (by sending a Syncflag), it shall ignore subsequent SOS requests with the same message ID. + +For single latency with ROC mode, the L and D values for latency path #0 shall be ignored by the receiver. + +**Table 11-7 – OLR responses sent by the responding VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-----------------------|-----------------|--------------|--------------------------------------|-------------------| +| Defer Type 1 request | 3 | 2 | 81 16 (Note) | Mandatory | +| | | 3 | 1 octet for reason code (Table 11-8) | | +| Reject Type 2 request | 3 | 2 | 82 16 (Note) | For further study | +| | | 3 | 1 octet for reason code (Table 11-8) | | +| Reject Type 3 request | 3 | 2 | 83 16 (Note) | Optional | +| | | 3 | 1 octet for reason code (Table 11-8) | | +| Reject Type 4 request | 3 | 2 | 84 16 (Note) | Optional | +| | | 3 | 1 octet for reason code (Table 11-8) | | +| Reject Type 5 request | 3 | 2 | 85 16 (Note) | Optional | +| | | 3 | 1 octet for reason code (Table 11-8) | | +| Reject Type 6 request | 3 | 2 | 86 16 (Note) | Optional | +| | | 3 | 1 octet for reason code (Table 11-8) | | +| IACK | 3 | 2 | 8B 16 (Note) | Mandatory | +| | | 3 | 1 octet for SC | | + +NOTE – All other values for octet number 2 are reserved by ITU-T. + +Each subcarrier parameter field shall contain 4 octets formatted as [0000 iiii iiii iiii gggg gggg gggg bbbb] to convey the $g_i$ (12 bits) and the $b_i$ (4 bits) values of the subcarrier index $i$ (12 bits). The subcarrier index $i$ shall be coded in the four LSBs of the first octet and the entire second octet of the subcarrier field. The LSBs of the subcarrier index $i$ shall be contained in the second octet. The $g_i$ shall be contained in the third octet and the four MSBs of the fourth octet. The LSBs of $g_i$ shall be contained in the fourth octet. The $b_i$ shall be contained in the four LSBs of the fourth octet. + +**Table 11-8 – Reason codes for OLR responses** + +| Reason | Octet value | Applicable to Defer Type 1 | Applicable to Reject Type 2 | Applicable to Reject Type 3 | Applicable to Reject Type 4 | +|--------------------|------------------|----------------------------|-----------------------------|-----------------------------|-----------------------------| +| Busy | 01 16 | yes | yes | yes | no | +| Invalid parameters | 02 16 | yes | yes | yes | yes | + +Upon sending an OLR command, the initiator shall await a response. The OLR response may be deferring or rejecting the reconfiguration, or it may be a Syncflag indicating when the reconfiguration shall take effect. If the initiator receives an OLR response to defer or reject the change, it shall abandon the last requested OLR command. A new command may be initiated immediately, including the command abandoned, rejected or deferred earlier. + +NOTE 1 – In the case of reason code 0216, repeating of the OLR request is not expected to be helpful. + +NOTE 2 – When an OLR command has been sent, the initiator has no means to cancel the command. The initiator needs to wait for a response or a time-out before it can send a different OLR command. For example, if the SOS triggering conditions become active when there is a pending bitswap or SRA, the SOS request needs to be delayed until full execution or time-out of the bitswap/SRA procedure. + +Upon reception of an OLR command, the responder shall send either an OLR response to defer or to reject the reconfiguration, or a Syncflag that indicates when the reconfiguration shall take effect. After sending the Syncflag, the responder shall reconfigure the affected PMD, PMS-TC, and TPS-TC functions starting from the tenth symbol in the next DMT superframe, as described in clause 13.3. The responder may defer or reject the OLR request; in this case it shall supply a reason code from those specified in Table 11-8. + +Upon reception of the Syncflag, the initiator shall reconfigure the affected PMD or PMS-TC functions starting from the tenth DMT symbol in the next DMT superframe, as described in clause 13.3. + +#### 11.2.3.4 Diagnostic commands and responses + +The Diagnostic commands shall be used to control the VTU diagnostic capabilities defined in this clause. The Diagnostic commands shown in Table 11-9 may be initiated only by the VTU-O. The Diagnostic commands shown in Table 11-10 may be initiated only by the VTU-R. The responses are shown in Table 11-11. All Diagnostic commands and responses shall consist of two or three octets. The first octet shall be the assigned value for the Diagnostic command type, as shown in Table 11-4. The second and subsequent octets shall be as shown in Tables 11-9 and 11-10 for commands and in Table 11-11 for responses. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-9 – Diagnostic commands sent by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|-------------------------| +| Perform self-test | 2 | 2 | 01 16 (Note) | +| Update Test Parameters | 2 | 2 | 02 16 (Note) | +| Start TX Corrupt CRC | 2 | 2 | 03 16 (Note) | +| End TX Corrupt CRC | 2 | 2 | 04 16 (Note) | +| Start RX Corrupt CRC | 2 | 2 | 05 16 (Note) | +| End RX Corrupt CRC | 2 | 2 | 06 16 (Note) | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-10 – Diagnostic commands sent by the VTU-R** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|-------------------------| +| Update test Parameters | 2 | 2 | 02 16 (Note) | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-11 – Diagnostic responses sent by the VTU** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|-----------------------------------------------------------------------------------------------------| +| Self-test Acknowledge (VTU-R only) | 3 | 2 | 01 16 (Note) | +| | | 3 | 1 octet for the minimum time in seconds the VTU-O shall wait before requesting the self-test result | +| ACK (VTU-O and VTU-R) | 2 | 2 | 80 16 (Note) | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +A Diagnostic command may be sent at any time during showtime, including immediately following the end of the initialization procedure. In all cases, reception of a Diagnostic command shall be acknowledged to the initiator (by an ACK or by a self-test Acknowledge response). + +NOTE – A negative acknowledge (NACK) is not used for Diagnostic commands. + +##### **11.2.3.4.1 Perform self-test** + +Upon reception of the Perform self-test command, the VTU-R shall respond with a self-test Acknowledge, which indicates the minimum amount of time that the VTU-O shall wait before requesting the results of the self-test. Further, the VTU-R shall perform the self-test and generate the self-test result. The self-test procedure is vendor discretionary, but it shall not interfere with the functions of the VTU-R, shall not impact the status of the connection, and its duration shall not exceed 255 s. The VTU-R shall obtain and store the result of the self-test within the number of seconds indicated in the self-test Acknowledge response. The indicated amount of time shall be an integer between 1 s and 255 s. + +The self-test results may be accessed using the Inventory command defined in clause 11.2.3.6. The length of the self-test results shall be 4 octets. The first octet (including the MSB) shall be 0016 if the self-test passed and 0116 if it failed. The meaning of "failure" is vendor discretionary. The contents of the three other octets are vendor discretionary. + +##### **11.2.3.4.2 Update Test Parameters** + +Upon reception of the Update Test Parameters command, the requested VTU shall send the ACK response and update the test parameter set defined in clause 11.4.1. All test parameters that can be updated during showtime shall be updated and stored within 10 s after the request is received. Upon reception of the ACK response, the requesting VTU shall wait at least 10 s before sending the PMD Test Parameter Read commands defined in clause 11.2.3.11 to access the test parameter values defined in clause 11.4.1. + +The test parameter values relating to the most recent initialization procedure shall no longer be accessible through the Test Parameter Read commands within 10 s after the Update Test Parameters command was received. They may be discarded by the responding VTU immediately upon reception of the Update Test Parameter command. + +##### **11.2.3.4.3 Start/End transmitter Corrupt CRC** + +Upon reception of the Start Transmitter (TX) Corrupt CRC command, the VTU-R shall send the ACK response and its PMS-TC shall generate a corrupted CRC value in all transmitted latency paths until cancelled by the End TX Corrupt CRC command. A corrupted CRC value is any one that does not correspond to the CRC procedure specified in clause 9.5.2.3. The Start TX Corrupt CRC command shall affect only the CRC value transmitted by the VTU-R; the PMS-TC function of the VTU-O shall not be affected by this command. + +Upon reception of the End TX Corrupt CRC command, the VTU-R shall send the ACK response and its PMS-TC shall generate CRC values in all latency paths as specified in clause 9.5.2.3. The End TX Corrupt CRC command shall not affect the PMS-TC function of the VTU-R if the Start TX Corrupt CRC command has not been sent earlier. + +##### **11.2.3.4.4 Start/End receiver Corrupt CRC** + +Upon reception of the Start receiver (RX) Corrupt CRC command, the VTU-R shall send the ACK response. Upon reception of this ACK response by the VTU-O, its PMS-TC function shall generate a corrupted CRC value in all transmitted latency paths until cancelled by the End RX corrupt CRC command. A corrupted CRC value is any one that does not correspond to the CRC procedure specified in clause 9.5.2.3. The Start RX Corrupt CRC command shall affect only the CRC value transmitted by the VTU-O; the PMS-TC function of the VTU-R shall not be affected by this command. + +Upon reception of the End RX Corrupt CRC command, the VTU-R shall send the ACK response. Upon reception of this ACK response, the PMS-TC function at the VTU-O shall generate CRC values in all latency paths as specified in clause 9.5.2.3. The End RX Corrupt CRC command shall not affect the PMS-TC function of the VTU-O if the Start RX Corrupt CRC command has not been sent earlier. + +NOTE – The Start RX Corrupt CRC command may be used in conjunction with the Transmit Corrupt CRC command (either previously or subsequently) so that CRC values are set corrupted in both directions of transmission. + +#### 11.2.3.5 Time commands and responses + +Both VTUs shall maintain timers to update performance monitoring counters as described in [ITU-T G.997.1]. The time commands shall be used to synchronize timers at both ends of the link. The timers shall have an accuracy of $\pm 100$ ppm or better. + +NOTE – The counters defined in [ITU-T G.997.1] should be updated each time the time counter contains a time value that is an integer multiple of 15 minutes (e.g., 1:00:00, 3:15:00, 15:30:00, 23:45:00). + +The time commands are shown in Table 11-12, and may only be initiated by the VTU-O. The VTU-R shall reply using one of the responses shown in Table 11-13. The first octet of all time commands and responses shall be the assigned value for the time command type, as shown in Table 11-4. The remaining octets shall be as specified in Tables 11-12 and 11-13 for commands and responses, respectively. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-12 – Time commands sent by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|--------------------------------------------------------------| +| Set Time | 10 | 2 | 01 16 (Note) | +| | | 3 to 10 | 8 octets for time value formatted as HH:MM:SS per [ISO 8601] | +| Read Time | 2 | 2 | 02 16 (Note) | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-13 – Time responses sent by the VTU-R** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|--------------------------------------------------------------| +| ACK | 2 | 2 | 80 16 (Note) | +| Time | 10 | 2 | 82 16 (Note) | +| | | 3 to 10 | 8 octets for time value formatted as HH:MM:SS per [ISO 8601] | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +Upon reception of the Set Time command, the VTU-R shall send the ACK response, and set its timer to the value contained in the message. + +Upon reception of the Read Time command, the VTU-R shall send the Time response that includes the current value of the VTU-R timer. + +#### 11.2.3.6 Inventory commands and responses + +The Inventory commands shall be used to determine the identification and capabilities of the VTU at the far end. The Inventory commands shown in Table 11-14 may be initiated by either VTU. The Inventory responses shall be as shown in Table 11-15. The first octet of all Inventory commands and responses shall be the assigned value for the Inventory command type, as shown in Table 11-4. The + +second octet of the Inventory commands shall be as specified in Table 11-14. The second octet (ACK) and all following octets of the Inventory responses shall be as specified in Table 11-15. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-14 – Inventory commands sent by the requesting VTU** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|-------------------------| +| Identification request | 2 | 2 | 01 16 (Note) | +| Auxiliary Inventory Information request | 2 | 2 | 02 16 (Note) | +| Self-test results request | 2 | 2 | 03 16 (Note) | +| Initialization Flags request | 2 | 2 | 04 16 (Note) | +| Initialization Flags Reset request | 2 | 2 | 05 16 (Note) | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-15 – Inventory responses sent by the responding VTU** + +| Name | Length (Octets) | Octet number | Contents | +|-------------------------------------------------------------------|-----------------|--------------|----------------------------------------------------------------------| +| ACK (Identification) | 58 | 2 | 81 16 (Note) | +| | | 3 to 10 | 8 octets of vendor ID | +| | | 11 to 26 | 16 octets of version number | +| | | 27 to 58 | 32 octets of serial number | +| ACK (Auxiliary Inventory Information) | variable | 2 | 82 16 (Note) | +| | | 3 to 10 | 8 octets of vendor ID | +| | | 11 + | Multiple octets of auxiliary inventory information | +| Self-test Results | 6 | 2 | 83 16 (Note) | +| | | 3 to 6 | 4 octets of self-test results | +| Initialization Flags | 3 | 2 | 84 16 (Note) | +| | | 3 | 1 octet with the value of the initialization flags. | +| Initialization Flags Reset | 3 | 2 | 85 16 (Note) | +| | | 3 | 1 octet with the value of the initialization flags before the reset. | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +Upon reception of one of the Inventory commands, the VTU shall send the corresponding response. Any function of either the requesting or the responding VTU shall not be affected by the command. + +The vendor ID in the response identifies the system integrator and shall be formatted according to the vendor ID of [ITU-T G.994.1]. In the context of this request, the system integrator usually refers to the vendor of the smallest field-replaceable unit; thus, the vendor ID in the response may not be the same as the vendor ID indicated during the ITU-T G.994.1 handshake phase of initialization. + +The VTU-O version number shall be as defined in clause 7.4.5 of [ITU-T G.997.1]. + +The VTU-R version number shall be as defined in clause 7.4.6 of [ITU-T G.997.1]. + +The VTU-O serial number shall be as defined in clause 7.4.7 of [ITU-T G.997.1]. + +The VTU-R serial number shall be as defined in clause 7.4.8 of [ITU-T G.997.1]. + +The auxiliary inventory information shall be assigned with respect to the same system integrator as contained in the vendor ID. The syntax of this field is beyond the scope of this Recommendation. + +The self-test results response shall contain the results from the most recent self-test procedure, initiated either at power-up or by the eoc command Perform self-test. The results shall be formatted as defined in clause 11.2.3.4.1. + +The eoc commands Initialization Flags request and the Initialization Flags Reset request shall only be supported from the VTU-O to the VTU-R. The responses to those commands are optional. + +The Initialization Flags and the Initialization Flags Reset response shall contain the current value of the initialization flags. The following initialization flags are defined: + +- The "previous-loss-of-power" (PLPR) flag: This flag shall be set to 1 after a power-up of the VTU-R due to an interruption in the VTU-R electrical supply (mains) power. The flag shall be set to 0 after sending the Initialization Flags Reset response; +- The "previous host re-init" (PHRI) flag: This flag shall be set to 1 after a power-up of the VTU-R triggered by the CPE host. The flag shall be set to 0 after sending the Initialization Flags Reset response. + +The value of the initialization flags shall be formatted as 1 octet [0000 00ba] where "a" is the value of the PLPR flag and "b" is the value of the PHRI flag. + +#### 11.2.3.7 Management counter read commands and responses + +The Management counter read request command shall be used to retrieve the current value of certain management counters maintained by the far-end VTU in accordance with [ITU-T G.997.1]. The Management counter read request command is shown in Table 11-16, and may be initiated by either VTU and is used to request the values of the counters. The response shall be as shown in Table 11-17. The first octet of the command and response shall be the assigned value for the Management counter read command type, as shown in Table 11-4. The second octet of the command shall be as shown in Table 11-16. The second and all following octets of the response shall be as shown in Table 11-17. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-16 – Management counter read commands sent by the requesting VTU** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|-------------------------| +| Request | 2 | 2 | 01 16 (Note) | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-17 – Management counter read responses sent by the responding VTU** + +| Name | Length (Octets) | Octet number | Content | +|------|-----------------|------------------------------------------------|------------------------------------------------------| +| ACK | variable | 2 | 81 16 (Note 1) | +| | | 3 to $2 + 4 \times (2 \times N_{LP} + 5)$ | Octets for all of the PMS-TC counter values (Note 2) | +| | | $3 + 4 \times (2 \times N_{LP} + 5)$ and above | Octets for all of the TPS-TC counter values (Note 2) | + +NOTE 1 – All other values for octet number 2 are reserved by ITU-T. +NOTE 2 – $N_{LP}$ is the number of enabled latency paths. + +Upon reception of the management counter read request command, the VTU shall send the response. Any function of either the requesting or the responding VTU shall not be affected by the command. + +The management counter values shall be derived according to [ITU-T G.997.1] from locally generated defects and anomalies defined within clause 11.3. The parameters shall be transferred in the order (top to bottom) defined in Table 11-18. The TPS-TC anomaly definitions and relevant management counters are dependent upon the TPS-TC type and shall be as defined in Annex L. All counter values are defined as 32-bit counters and shall be mapped to the response in order of most significant to least significant octet. No octets shall be inserted into the response for latency paths and TPS-TC functions that are currently disabled. + +The counters shall be reset at power-up, and shall not be reset upon a link state transition, and shall not be reset upon read. The time periods when the VTU is powered but not in the showtime state shall be counted as unavailable seconds (see clause 7.2.1.1.5 of [ITU-T G.997.1]). + +**Table 11-18 – VTU management counters** + +| PMS-TC counters | +|-------------------------------------| +| Counter of the FEC-0 anomalies | +| Counter of the FEC-1 anomalies | +| Counter of the CRC-0 anomalies | +| Counter of the CRC-1 anomalies | +| FEC errored seconds counter | +| Errored seconds counter | +| Severely errored seconds counter | +| los errored seconds counter | +| Unavailable errored seconds counter | +| TPS-TC counters | +| Counters for TPS-TC #0 | +| Counters for TPS-TC #1 | + +NOTE – The VTU-O should respond to the request from the NMS to read the values of management counters. It is left to the implementations to store and update the counters as necessary for accurate error monitoring and reporting. + +#### 11.2.3.8 Clear eoc commands and responses + +The Clear eoc Request command may be used by the ITU-T G.997.1 function to transfer management octets between the EIA and the VTU-R and from one VTU to another (see clause 6 of [ITU-T G.997.1]). The Clear eoc Request command is shown in Table 11-19 and may be initiated by + +either VTU. The responses shall be as shown in Table 11-20. The first octet of either the command or a response shall be the assigned value for the Clear eoc command type shown in Table 11-4. The subsequent octets of the command shall be as shown in Table 11-19. The subsequent octets of the responses shall be as shown in Table 11-20. The octets shall be sent using the format described in clause 11.2.3.1. + +NOTE – In accordance with [ITU-T G.997.1], the information payload of the Clear eoc message does not exceed 510 octets. Therefore, the length of either a Clear eoc Request command or a response does not exceed 516 octets. + +**Table 11-19 – Clear eoc commands sent by the initiating VTU** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|---------------------------------------------------------------------------------| +| Request | variable | 2 | 01 16 (Note) | +| | | 3 + | the information payload of the clear eoc message to be delivered to the far end | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-20 – Clear eoc responses sent by the responding VTU** + +| Name | Length (Octets) | Octet number | Content | +|--------------------------------------------------------------------------|-----------------|--------------|-------------------------| +| ACK | 2 | 2 | 80 16 (Note) | +| NACK | 3 | 2 | 81 16 (Note) | +| | | 3 | 04 16 (Note) | +| NOTE – All other values for octet numbers 2 and 3 are reserved by ITU-T. | | | | + +Upon reception of the Clear eoc Request command, the VTU shall respond with an acknowledgement (ACK) and deliver the received clear eoc message to the local ITU-T G.997.1 management function transparently, with the original formatting used by the ITU-T G.997.1 management function of the initiating VTU. The VTU may instead respond with a negative acknowledge (NACK) including the Not Supported (value 0416) reason code, indicating that the received clear eoc message cannot be delivered to the ITU-T G.997.1 management function (because the ITU-T G.997.1 management function may not support clear eoc messages; see clause 6 of [ITU-T G.997.1]). Other reason codes are for further study. + +#### 11.2.3.9 Power management commands and responses + +The Power Management L3 Request command shall be used to propose a power management transition to link state L3. The Power Management L3 Request command is shown in Table 11-21 and may be initiated by either VTU. The responses shall be as shown in Table 11-22. The first octet of either the command or a response shall be the assigned value for the Power Management command type, as shown in Table 11-4. The remaining octets shall be as shown in Tables 11-21 and 11-22 for commands and responses, respectively. + +**Table 11-21 – Power management commands sent by the initiating VTU** + +| Name | Length (Octets) | Octet number | Content | +|--------------------------------------------------------------------------|-----------------|--------------|-------------------------| +| L3 Request | 3 | 2 | 01 16 (Note) | +| | | 3 | 03 16 (Note) | +| NOTE – All other values for octet numbers 2 and 3 are reserved by ITU-T. | | | | + +**Table 11-22 – Power management responses sent by the responding VTU** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------------------------------------------------|-----------------|--------------|-------------------------| +| Grant | 2 | 2 | 80 16 (Note) | +| Reject | 3 | 2 | 81 16 (Note) | +| | | 3 | 1 octet for reason code | +| NOTE – All other values for octet number 2 are reserved by ITU-T. | | | | + +Reason codes associated with the power management commands are shown in Table 11-23. + +**Table 11-23 – Reason codes for power management commands** + +| Reason | Octet value | +|-------------------|------------------| +| Busy | 01 16 | +| Invalid | 02 16 | +| State not desired | 03 16 | + +##### 11.2.3.9.1 L3 Request by VTU-R + +Upon receipt of the L3 Request command, the responding VTU-O shall send either the Grant or Reject response. The proposed link state shall be formatted as 0316 for the L3 link state. If any other link state is received, the Reject response shall be sent with the reason code 0216. + +The VTU-O may reject a request to move to link state L3 using reason code 0116 because it is temporarily too busy, or reject it using code 0316 because it has local knowledge that the L3 state is not desired at this time. Upon receipt of the L3 Request command, the VTU-O may immediately start the protocol to request a transition to the L3 state. + +If the VTU-R receives the Grant response, the VTU-R shall stop transmitting. When the VTU-O observes the stopped transmission, it shall also stop transmitting. + +##### 11.2.3.9.2 L3 Request by VTU-O + +Upon receipt of the L3 Request command, the responding VTU-R shall send either the Grant or Reject response. The proposed link state shall be formatted as 0316 for the L3 link state. If any other link state is received, the Reject response shall be sent with the reason code 0216. + +The VTU-R may reject a request to move to link state L3 using reason code 0116 because it is temporarily too busy, or reject it using code 0316 because it has local knowledge that the L3 state is not desired at this time. Upon receipt of the L3 Request command, the VTU-R may immediately start the protocol to request a transition to the L3 state. + +If the VTU-O receives the Grant response, the VTU-O shall stop transmitting. When the VTU-R observes the stopped transmission, it shall also stop transmitting. + +#### 11.2.3.10 Non-standard facility commands and responses + +The non-standard facility (NSF) commands may be used to exchange vendor-discretionary information between the VTUs. The NSF Request command is shown in Table 11-24 and may be initiated by either VTU to request the non-standard information. The responses shall be as shown in Table 11-25. The first octet of either the command or a response shall be the assigned value for the NSF command type, as shown in Table 11-4 for normal priority NSF commands, or in Table 11-5 for low priority NSF commands. The remaining octets of normal priority and low priority commands shall be as shown in Table 11-24. The second octet of normal priority and low priority responses shall be as shown in Table 11-25. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-24 – NSF commands sent by the requesting VTU** + +| Name | Length (Octets) | Octet number | Content | +|---------|-----------------|--------------|--------------------------------------| +| Request | variable | 2 | 01 16 (Note) | +| | | 3 to 8 | 6 octets of NSF identifier field | +| | | 9 + | multiple octets of NSF message field | + +NOTE – All other values for octet number 2 are reserved by ITU-T. + +**Table 11-25 – NSF responses sent by the responding VTU** + +| Name | Length (Octets) | Octet number | Content | +|------|-----------------|--------------|-------------------------| +| ACK | 2 | 2 | 80 16 (Note) | +| NACK | 2 | 2 | 81 16 (Note) | + +NOTE – All other values for octet number 2 are reserved by ITU-T. + +Upon reception of the NSF Request command, the VTU shall respond with an acknowledgement (ACK) to indicate that both the NSF identifier field and the message field are recognized, or respond with a negative acknowledgement (NACK) if either the NSF identifier field or NSF message field is not recognized. + +The combination of the NSF identifier field and NSF message field corresponds to a non-standard information block as defined in Figure 11 of [ITU-T G.994.1] (without the length-indicator octet). The NSF identifier field shall consist of 6 octets. The first 2 octets shall be a country code, and the remaining 4 octets shall be a provider code as specified by the country. Both values shall be set as defined in [ITU-T T.35]. The NSF message field contains vendor-specific information. The syntax of the NSF message field shall be as defined in Figure 11 of [ITU-T G.994.1] (without the length-indicator octet). + +#### 11.2.3.11 PMD Test Parameter Read commands and responses + +The PMD Test Parameter Read commands shall be used to retrieve the values of the PMD test parameters that are specified in clause 11.4.1 and maintained by the far-end VTU. The PMD Test Parameter Read commands are shown in Table 11-26, and may be initiated by either VTU. The responses shall be as shown in Table 11-27. The first octet of all PMD Test Parameter Read commands and responses shall be the assigned value for the PMD Test Parameter Read command type, as shown in Table 11-5. The subsequent octets of the commands shall be as shown in Table 11-26. The subsequent octets of the responses shall be as shown in Table 11-27. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-26 – PMD test parameter read commands sent by the requesting VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|--------------------|-----------------|--------------|---------------------------|-----------| +| Single Read | 2 | 2 | 01 16 (Note 1) | Mandatory | +| Next Multiple Read | 2 | 2 | 03 16 (Note 1) | Mandatory | +| | 4 | 2 | 04 16 (Note 1) | Mandatory | + +**Table 11-26 – PMD test parameter read commands sent by the requesting VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-------------------|-----------------|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| Multiple Read | | 3 to 4 | 2 octets describing the subcarrier group index | | +| Block Read | 6 | 2 | 05 16 (Note 1) | Mandatory | +| | | 3 to 4 | 2 octets describing the start subcarrier group index | | +| | | 5 to 6 | 2 octets describing the stop subcarrier group index | | +| Vector Block Read | 7 | 2 | 06 16 (Note 1) | Optional | +| | | 3 | 1 octet describing the type of test parameter to read (Note 2)
01 16 : Channel transfer function Hlog( f ) per subcarrier group
03 16 : Quiet Line Noise PSD QLN( f ) per subcarrier group
04 16 : Signal to noise ratio SNR( f ) per subcarrier group. | | +| | | 4 to 5 | 2 octets describing the start subcarrier group index | | +| | | 6 to 7 | 2 octets describing the stop subcarrier group index | | +| | | | | | +| Scalar Read | 3 | 2 | 07 16 (Note 1) | Optional | +| | | 3 | 1 octet describing the type of scalar test parameters to be read (Note 2)
21 16 to 28 16 : the parameter index to read according to the ID of Table 11-28. | | + +NOTE 1 – All other values for octet number 2 are reserved by the ITU-T. +NOTE 2 – All other values for octet number 3 are reserved by the ITU-T. + +**Table 11-27 – PMD test parameter read responses sent by the responding VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-----------------------|------------------------------|--------------|----------------------------------------------------------------------|-----------| +| Single Read ACK | 42 (Note 1) | 2 | 81 16 (Note 2) | Mandatory | +| | | 3 to 42 | Octets for the test parameters arranged for the single read format | | +| Multiple Read ACK | 12 (Note 1) | 2 | 82 16 (Note 2) | Mandatory | +| | | 3 to 12 | Octets for the test parameters arranged for the multiple read format | | +| NACK | 2 | 2 | 80 16 (Note 2) | Mandatory | +| Block Read ACK | Parameter-dependent (Note 1) | 2 | 84 16 (Note 2) | Mandatory | +| | | 3 + | Octets for the test parameters arranged for the block read format | | +| Vector Block Read ACK | Parameter-dependent (Note 1) | 2 | 86 16 (Note 2) | Optional | +| | | 3 + | Octets for the test parameters arranged for the block read format | | + +**Table 11-27 – PMD test parameter read responses sent by the responding VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-----------------|------------------------------|--------------|--------------------------------------------------------------------|----------| +| Scalar Read ACK | Parameter-dependent (Note 1) | 2 | 87 16 (Note 2) | Optional | +| | | 3 + | Octets for the test parameters arranged for the scalar read format | | + +NOTE 1 – Message length equals 2 octets plus the length shown in Table 11-28. +NOTE 2 – All other values for octet number 2 are reserved by the ITU-T. + +**Table 11-28 – PMD test parameter ID values and length of responses** + +| Test parameter ID (Note 1) | Test parameter name | Length for Single Read (octets) | Length for Multiple Read (octets) | Length for Block Read or Vector Block Read (octets) | Length for Scalar Read (octets) | Support | +|----------------------------|--------------------------------------------------------|---------------------------------|-----------------------------------|-----------------------------------------------------------------------------------|---------------------------------|-----------| +| 01 16 | Channel transfer function Hlog(f) per subcarrier group | N/A | 4 | 2 + (stop subcarrier group index – start subcarrier group index + 1) × 2 (Note 2) | N/A | Mandatory | +| 03 16 | Quiet line noise PSD QLN(f) per subcarrier group | N/A | 3 | 2 + (stop subcarrier group index – start subcarrier group index + 1) (Note 2) | N/A | Mandatory | +| 04 16 | Signal-to-noise ratio SNR(f) per subcarrier group | N/A | 3 | 2 + (stop subcarrier group index – start subcarrier group index + 1) (Note 2) | N/A | Mandatory | +| 21 16 | Loop attenuation (LATN) | 2 × 5 | N/A | N/A | 2 × 5 | Mandatory | +| 22 16 | Signal attenuation (SATN) | 2 × 5 | N/A | N/A | 2 × 5 | Mandatory | +| 23 16 | Signal-to-noise ratio margin (SNRM) and SNRM-pb | 2 × 6 | N/A | N/A | 2 × 6 | Mandatory | +| 24 16 | Attainable net data rate ATTNDR (basic method) | 4 | N/A | N/A | 4 | Mandatory | +| 24 16 | Attainable net data rate ATTNDR (improved method) | 8 | N/A | N/A | 8 | Optional | + +**Table 11-28 – PMD test parameter ID values and length of responses** + +| Test parameter ID (Note 1) | Test parameter name | Length for Single Read (octets) | Length for Multiple Read (octets) | Length for Block Read or Vector Block Read (octets) | Length for Scalar Read (octets) | Support | +|----------------------------|--------------------------------------------------------------------------------------|---------------------------------|-----------------------------------|-----------------------------------------------------|---------------------------------|-----------| +| 25 16 | Near-end actual aggregate transmit power ACTATP | 2 | N/A | N/A | 2 | Mandatory | +| 26 16 | Far-end actual aggregate transmit power ACTATP | 2 | N/A | N/A | 2 | Mandatory | +| 27 16 | Far-end actual impulse noise protection INP_act | N/A | N/A | N/A | 2 | Optional | +| 28 16 | Far-end actual signal-to-noise ratio margin for the robust overhead channel SNRM-ROC | N/A | N/A | N/A | 2 | Optional | + +NOTE 1 – All other Test parameter ID values are reserved by the ITU-T. +NOTE 2 – Since the number of subcarriers, $G$ , in the subcarrier group (see clause 11.4.1) may be different for QLN, Hlog, and SNR, the values of QLN, Hlog and SNR communicated by Multiple Read, Block Read, or Vector Block Read for the same subcarrier group index may correspond to different subcarrier indices. The subcarrier index for each parameter equals $G \times \text{subcarrier group\_index}$ , where the value of $G$ is as defined in Table 11-42 of clause 11.4.1 (for showtime) and subcarrier group index = 0 to 511. + +Upon reception of a PMD Test Parameter Read command, the responding VTU shall send the corresponding response. If the format of the Test Parameter Read command is incorrect, the VTU shall respond with the negative acknowledge (NACK). Any function of either the requesting or the responding VTU shall not be affected. + +The Single Read command shall be used to retrieve all test parameters with ID values from 2116 to 2616 inclusive. In response to a Single Read command, the values for the test parameters (one value per parameter) shall be transferred in numerically increasing order of the parameter ID shown in Table 11-28. The format of the octets for each parameter shall be as specified in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The loop attenuation (LATN), signal attenuation (SATN) and signal-to-noise ratio margin (SNRM) format shall include five 2-octet values intended for 5 potentially available frequency bands for each transmission direction. The 2-octet values shall be sent in the order shown in Table 11-29. The value 0016 shall be used to indicate the disabled bands. Octets indicated as reserved shall be set to ZERO in the transmitter and ignored by the receiver. The SNRM test parameter shall, in addition to all SNRM-pb values (clause 11.4.1.1.6.3), include the overall SNRM value (clause 11.4.1.1.6.2). The first 2-octet value is the overall SNRM, followed by the five 2-octet values of the SNRM-pb as specified in Table 11-29. For the ATTNDR, the use of either the basic or the improved method is configured during initialization (see clause 11.4.1.1.7). The ATTNDR test parameter is specified in Table 11-30. + +**Table 11-29 – Order for sending LATN, SATN and SNRM-pb parameters** + +| Octet number | Upstream direction | Downstream direction | +|--------------|--------------------|----------------------| +| 1 | US0 | DS1 | +| 2 | | | +| 3 | US1 | DS2 | +| 4 | | | +| 5 | US2 | DS3 | +| 6 | | | +| 7 | US3 | DS4 | +| 8 | | | +| 9 | US4 | Reserved | +| 10 | | | + +**Table 11-30 – ATTNDR test parameter** + +| Octet number | Basic method | Improved method | +|--------------|---------------|--------------------------------------| +| 1-4 | ATTNDR | ATTNDR | +| 5 | N/A | Reserved and set to 00 16 | +| 6 | N/A | ATTNDR_INP_act0 | +| 7 | N/A | Reserved and set to 00 16 | +| 8 | N/A | ATTNDR_delay_act0 | + +NOTE – The format of the fields is defined in clause 11.4.1.1.7. + +A Scalar Read command shall be used to retrieve a single test parameter. Support of this read command is optional. The ID of the test parameter to retrieve shall be indicated in the third octet of the read command as specified in Table 11-26. In response to a Scalar Read command, the VTU shall send the value of the test parameter if this command and the test parameter are supported by the VTU; otherwise the VTU shall send a NACK. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The format of the LATN, SATN, SNRM and ATTNDR shall be identical to the format used in Single Read Command. The Far-end actual impulse noise protection (ID=2716) shall include two 1-octet values and be sent in the order shown in Table 11-31. The value FF16 shall be used to indicate the disabled bearers. + +**Table 11-31 – Order for sending far-end actual impulse noise protection parameters** + +| Octet number | Parameter | +|--------------|------------------------------| +| 1 | INP_act for bearer channel 0 | +| 2 | INP_act for bearer channel 1 | + +Multiple Read and Next Multiple Read commands shall be used to retrieve test parameters of one subcarrier group. In response to a Multiple Read or Next Multiple Read command, the VTU shall send information for test parameters with ID 0116, 0316, and 0416 associated with the indicated + +subcarrier group. The Multiple Read command contains the index of the requested subcarrier group (see Table 11-26). If a Next Multiple Read command is to be sent, it shall only be sent after a Multiple Read command. In response to each subsequent Next Multiple Read command, the subcarrier group index shall be incremented by one. If the subcarrier group index exceeds 511 (see clause 11.4.1), the response shall be a NACK. The values of the PMD parameters per subcarrier group shall be inserted into the message in numerical order of the parameter ID shown in Table 11-28. The format of the octets for each parameter shall be as described in clause 11.4.1. Values that are formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. + +A Block Read command shall be used to retrieve test parameters over a range of subcarrier groups. In response to a Block Read command, the VTU shall send information for test parameters with ID 0116, 0316, and 0416 associated with the specified block of subcarrier groups. For test parameters specified per subcarrier group, all values for subcarrier groups with indices from #start to #stop are transferred in a single response. If the subcarrier group index exceeds 511, the response shall be a NACK. The values of the PMD parameters per subcarrier group shall be inserted into the message in increasing order of the parameter ID shown in Table 11-28. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The number of octets in a Block Read command shall not exceed the maximum length $P$ of the eoc message specified in clause 11.2.3.1. + +A Vector Block Read command shall be used to retrieve a single test parameter over a range of subcarrier groups. Support of this read command is optional. The ID of the test parameter to retrieve shall be indicated in the third octet of the read command as specified in Table 11-26. In response to a Vector Block Read command, the VTU shall send information for the test parameter associated with the specified block of subcarrier groups if this command is supported by the VTU; otherwise the VTU shall send a NACK. All values for subcarrier groups with indices from #start to #stop are transferred in a single response. If the subcarrier group index exceeds 511, the response shall be a NACK. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. + +When transferring values of the channel transfer function $H\log(f)$ , the quiet line noise $QLN(f)$ , and the signal-to-noise ratio $SNR(f)$ , the measurement time shall be included in the response for each test parameter. The ACK (see Table 11-27) is followed by the $H\log(f)$ measurement time and the value $m$ (see clause 11.4.1.1.1), followed by the $QLN(f)$ measurement time and value $n$ (see clause 11.4.1.1.2), followed by the $SNR(f)$ measurement time and value $SNR$ (see clause 11.4.1.1.3), respectively. The measurement time shall be included only once in a response to a Block Read or Vector Block Read command and shall be included for each test parameter in each response to a Multiple Read or Next Multiple Read command. + +The values of some test parameters are represented using fewer bits than contained in the corresponding field defined for the response in Table 11-28. In the case that the field has more than one octet, the bits shall be mapped to the LSBs of the multi-octet field in the response. Unused MSBs in the multi-octet field shall be set to ZERO for unsigned quantities and to the value of the sign bit for signed quantities. + +#### 11.2.3.12 Control Parameter Read commands and responses + +Control parameter read commands are for further study. + +#### 11.2.3.13 INM facility commands and responses + +A VTU that supports the impulse noise monitoring (INM) facility shall maintain INM counters to measure the impulse noise, as described in [ITU-T G.997.1]. The INM facility commands shall be used to update and read the INM parameters at the VTU-R. + +The INM facility command shall be used also to retrieve the current value of the INM counters maintained by the far-end VTU in accordance with [ITU-T G.997.1]. + +The INM facility commands are described in Table 11-32, and may only be initiated by the VTU-O. The VTU-R shall reply using one of the responses shown in Table 11-33. The first octet of all INM facility commands and responses shall be the assigned value for the INM facility command type, as shown in Table 11-5. The remaining octets shall be as specified in Table 11-32 and Table 11-33 for commands and responses, respectively. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-32 – INM facility commands sent by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|------------------------------------------------------------|-----------------|--------------|--------------------------------------------------| +| Read INM counters | 2 | 2 | 02 16 | +| Set INM parameters | 6 or 7 | 2 | 03 16 | +| | | 3 to 6 or 7 | 4 or 5 octets of INM parameters: see Table 11-36 | +| Read INM parameters | 2 | 2 | 04 16 | +| All other values for octet number 2 are reserved by ITU-T. | | | | + +**Table 11-33 – INM facility responses sent by the VTU-R** + +| Name | Length (Octets) | Octet number | Content | +|------------------------------------------------------------|-----------------|-----------------------|-----------------------------------------------------------| +| ACK | 3 | 2 | 80 16 | +| | | 3 | 1 octet INM acceptance code: see Table 11-34 | +| NACK | 2 | 2 | 81 16 | +| INM counters | 107 | 2 | 82 16 | +| | | 3 to 2 + 4 × (17+1+8) | Octets for all of the INM counter values: see Table 11-35 | +| | | 107 | 1 octet INMDF | +| INM parameters | 6 or 7 | 2 | 84 16 | +| | | 3 to 6 or 7 | 4 or 5 octets of INM parameters: see Table 11-36 | +| All other values for octet number 2 are reserved by ITU-T. | | | | + +Upon reception of any INM facility command, the VTU-R shall send NACK in response if it does not support the INM procedure or the INM command is invalid. Upon reception of an INM facility set INM parameters command, the VTU-R shall send the ACK in response if it does support the INM procedure. + +In case all INM parameter values listed in the set INM parameters command are valid and supported by the VTU-R, the VTU-R shall accept all of the INM parameters contained in the command. The INM acceptance code (see Table 11-34) will indicate that the parameters are accepted. If, for any of the INM parameters, the value in the command is different from the value in active use by the INM, the VTU-R shall activate the new INM parameter values and reset the counters less than 1 second after sending the ACK. + +In case any INM parameter values listed in the set INM parameters command is valid but not supported by the VTU-R, the VTU-R shall not accept any of the INM parameters and shall not reset the counters. + +Upon reception of the INM facility read INM parameters command, the VTU-R shall send the INM parameters response that includes the current value of the VTU-R INM parameters. + +**Table 11-34 – VTU-R INM acceptance code** + +| Name | Octet No. | Content | +|---------------------|-----------|-----------------------------------------------------------| +| ACC-INM_INPEQ_MODE | 3 | 80 16 : value for INM_INPEQ_MODE accepted | +| NACC-INM_INPEQ_MODE | 3 | 81 16 : value for INM_INPEQ_MODE not supported | + +Upon reception of the INM facility read INM counters command, the VTU shall send the INM counters response, which includes the INMDF. Any function of either the requesting or the responding VTU shall not be affected by this command. + +The INM counter values shall be derived according to [ITU-T G.997.1] from locally generated defects and anomalies defined in clause 11.3. The parameters shall be transferred in the order (top to bottom) defined in Table 11-35. All counter values are defined as 32-bit counters and shall be mapped to the response in order of most significant to least significant octet. + +The INM counters shall be reset at power-up, and shall not be reset upon any link state transition, and shall not be reset upon read. They shall be reset at activation of the new INM parameter values. The reset value is zero. The INM counters and the procedure to update the counters shall work continuously and independently of other (proprietary or non-proprietary) features, e.g., the INM shall work in the presence of OLR and without interruption. + +NOTE – The VTU-O should respond to the request from the NMS to read the values of INM counters. It is left to the implementations to store and update the counters as necessary for accurate monitoring and reporting. + +**Table 11-35 – VTU-R INM counters** + +| INM counters | +|--------------------------------------------------| +| Counter of the INMAINPEQ 1 anomalies | +| Counter of the INMAINPEQ 2 anomalies | +| ... | +| Counter of the INMAINPEQ 16 anomalies | +| Counter of the INMAINPEQ 17 anomalies | +| Counter of the INMAIAT 0 anomalies | +| Counter of the INMAIAT 1 anomalies | +| ... | +| Counter of the INMAIAT 6 anomalies | +| Counter of the INMAIAT 7 anomalies | +| Counter of the INNAME anomalies | + +The VTU-R shall set the INM default flag (INMDF) to ONE whenever all active INM parameters are equal to the default values. The VTU-R shall set the INM default flag (INMDF) to ZERO whenever any active INM parameter is different from the default value. + +The INM parameter values shall be transferred in the order defined in Table 11-36 and mapped in order of most significant to least significant octet. + +**Table 11-36 – VTU-R INM parameters** + +| Octet No. | INM parameter | +|-----------|----------------------------------------------------------------------------------------------------------------------------| +| 3-4 | 2 octets:
  • The 9 LSBs are INMIATO
  • The 4 MSBs are INMIATS
| +| 5 | 1 octet: INMCC | +| 6 | 1 octet: INM_INPEQ_MODE | +| 7 | 1 octet: INM_INPEQ_FORMAT
This octet is present only if supported by both VTU-O and VTU-R (see Tables 12-49 and 12-60). | + +#### **11.2.3.14 Frequency Synchronization command** + +The VTU-O shall be capable of sending frequency synchronization command through the eoc if this mechanism is selected during initialization. The command is only in one direction, from VTU-O to VTU-R, and there is no response required. + +The ToD phase difference value and corresponding $t_1$ event number shall be encapsulated in an *eoc* message as follows: + +**Table 11-37 – Frequency Synchronization command sent by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|----------------------|-----------------|--------------|--------------------------------------------------------------------------| +| ToD phase difference | 5 | 2 | 03 16 (Note) | +| | | 3 | 1 octet representing the index of the $t_1$ event | +| | | 4 to 5 | 2 octets representing the ToD phase difference in units of 2 nanoseconds | + +NOTE – All other values for octet number 2 are reserved by ITU-T. + +If the VTU-R selects during initialization that the ToD phase difference values shall be transported through the eoc, then the VTU-O shall generate a ToD phase difference eoc message into the nearly-high priority queue for each super-frame. For each super-frame, the VTU-O shall send the most recent phase difference eoc message in the queue and shall discard older phase difference eoc messages. If the VTU-R selects during initialization to transport the ToD phase difference values through the OH frame, then the VTU-O shall not send phase difference eoc messages. + +#### **11.2.3.15 Time Synchronization command and responses** + +The VTU shall be capable of sending and receiving the Time Synchronization commands and responses listed in Table 11-38 (command sent by VTU-O) and Table 11-39 (response sent by VTU-R), respectively. The Timestamp command specified in Table 11-38 shall only be sent by the VTU-O. The Timestamp response specified in Table 11-39 shall only be sent by the VTU-R. The VTU-R may reject to run time synchronization procedure using responses listed in Table 11-39 with reason codes listed in Table 11-40, or positively acknowledge by transmitting an ACK response. + +The first octet of all Time Synchronization commands and responses shall be the assigned value for the Time Synchronization command type, as shown in Table 11-4. The remaining octets shall be as shown in Tables 11-38 and 11-39. The octets of the Time Synchronization commands and responses shall be set over the link as described in clause 11.2.3.1. + +**Table 11-38 – Time Synchronization commands sent by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|--------------------------------------------|-----------------|--------------|------------------------------------------------------------------------------------------------------------| +| ToD( $t_1$ )
ToD( $t_4$ )
Timestamps | 26 | 2 | 01 16 (Note 1) | +| | | 3 to 4 | 2 octet for the index of time stamp ToD( $t_1$ ) in units of a super-frame. | +| | | 5 to 10 | 6 octets describing the integer portion of the timestamp ToD( $t_1$ ) in units of seconds. | +| | | 11 to 14 | 4 octets describing the fractional portion of the timestamp ToD( $t_1$ ) in units of nanoseconds. (Note 2) | +| | | 15 to 16 | 2 octets for the index of time stamp ToD( $t_4$ ) in units of a superframe. | +| | | 17 to 22 | 6 octets describing the integer portion of the timestamp ToD( $t_4$ ) in units of seconds. | +| | | 23 to 26 | 4 octets describing the fractional portion of the timestamp ToD( $t_4$ ) in units of nanoseconds. (Note 2) | + +NOTE 1 – All other values for octet number 2 are reserved by ITU-T. +NOTE 2 – The nanosecond portion is always less than $10^9$ . + +The octets for the index of time stamp ToD( $t_1$ ) contain the value of the downstream super-frame counter when ToD( $t_1$ ) is taken by the VTU-O (i.e., at the $t_1$ event). This value shall be a multiple of 16. The octets for the index of time stamp ToD( $t_4$ ) contain the value of the upstream super-frame counter when ToD( $t_4$ ) is taken by the VTU-O (i.e., at $t_4$ event). The difference between the downstream super-frame counter at $t_1$ event and the upstream superframe counter at $t_4$ event shall be constant over Showtime (i.e., the pairing of the $t_1$ and $t_4$ events shall not change over Showtime). The $t_1$ event and the $t_4$ event shall be less than 1 superframe apart (i.e., 64.25 ms on the PMD sampling clock timebase if the CE length corresponds to $m = 5$ , see clause 10.4.4). The ToD( $t_1$ ), ToD( $t_2$ ), ToD( $t_3$ ), and ToD( $t_4$ ) time stamps are described as two parts. One is the integer portion of the timestamp in units of seconds and the other is the fractional portion of the timestamp in units of nanoseconds. The ToD( $t_1$ ), and ToD( $t_4$ ) time stamps shall represent the time offset between the current time of the Real-time Clock RTC-O at the VTU-O (i.e., the time elapsed since the epoch) at the $t_1$ and $t_4$ events respectively. The ToD( $t_2$ ), and ToD( $t_3$ ) timestamps shall represent the time of the Real-time Clock RTC-R at the VTU-R, (i.e., the time elapsed since the epoch) at the $t_2$ and $t_3$ events respectively. The epoch shall be the same for the Real-time Clock RTC-O and the Real-time Clock RTC-R, where this common epoch is set over the $\gamma$ -O reference point. + +NOTE – If at the $t_1$ event the Real-time Clock RTC-O shows +2.000000001 seconds have elapsed since the epoch, this is represented in the ToD( $t_1$ ) timestamp by seconds = 0x0000 0000 0002 and nanoseconds = 0x0000 0001. The epoch may be locally set by the DSLAM or may be an absolute instant in time. For example, if the epoch is the PTP epoch, this means that time-of-day = 1 January 1970 00:00:02.000000001. + +**Table 11-39 – Time Synchronization responses sent by the VTU-R** + +| Name | Length (Octets) | Octet number | Content | +|-----------------------------------------------------|-----------------|--------------|-----------------------------------------------------------------------------------------------| +| ToD( $t_2$ )
ToD( $t_3$ )
Timestamps
(ACK) | 26 | 2 | 81 16 (Note 1) | +| | | 3 to 4 | 2 octets for the index of $t_2$ time stamp. | +| | | 5 to 10 | 6 octets describing the integer portion of the timestamp in units of seconds. | +| | | 11 to 14 | 4 octets describing the fractional portion of the timestamp in units of nanoseconds. (Note 2) | +| | | 15 to 16 | 2 octets for the index of $t_3$ time stamp. | +| | | 17 to 22 | 6 octets describing the integer portion of the timestamp in units of seconds. | +| | | 23 to 26 | 4 octets describing the fractional portion of the timestamp in units of nanoseconds. (Note 2) | +| Reject | 3 | 2 | 82 16 (Note 1) | +| | | 1 | 1 octet for reason code (see Table 11-40) | + +NOTE 1 – All other values for octet number 2 are reserved by ITU-T. +NOTE 2 – The nanosecond portion is always less than $10^9$ . + +**Table 11-40 – Reason codes for Time Synchronization responses** + +| Reason | Octet value | +|-------------------------------------------------------------|------------------| +| Busy | 01 16 | +| Invalid parameters | 02 16 | +| $t_2$ and $t_3$ timestamps no longer available at the VTU-R | 03 16 | +| Still acquiring ToD frequency synchronization | 04 16 | + +The Timestamp command is used to send time stamps ToD( $t_1$ ) and ToD( $t_4$ ) from the VTU-O to the VTU-R. Upon reception of a Timestamp command, the VTU-R shall either send the time stamps ToD( $t_2$ ) and ToD( $t_3$ ) in an ACK response to indicate that the time synchronization procedure will be performed with the ToD( $t_1$ ), ToD( $t_2$ ), ToD( $t_3$ ) and ToD( $t_4$ ) timestamps, or send a reject response with a reason code from those specified in Table 11-40. + +The VTU-R shall store the $t_2$ (and related $t_3$ ) values for at least the three most recent downstream (and related upstream) reference samples with a $t_2$ event count that is a multiple of 16. The VTU-O should send the time synchronization command soon enough after the $t_1$ and $t_4$ events to assure the related $t_2$ and $t_3$ timestamps are still available at the VTU-R. + +If the VTU-R accepts the Timestamp command, the Timestamp response is used to send timestamps ToD( $t_2$ ), and ToD( $t_3$ ) from the VTU-R to the VTU-O. The ToD( $t_1$ ), ToD( $t_2$ ), ToD( $t_3$ ) and ToD( $t_4$ ) timestamps (in conjunction with other information) may be used at the network side to e.g., compensate for propagation delay asymmetry. At the customer premises side, propagation delay asymmetry shall not be compensated for. Other uses of the response reported time stamp values at the network side are for further study. + +#### 11.2.3.16 Data gathering commands and responses + +This clause defines the commands and responses to support the data gathering function defined in clause 11.5. If the VTU-R supports the data gathering function, then the VTU-R shall keep a buffer of data gathering records, with each data gathering record relating to one of the event types listed in Table 11-43. Data gathering records shall be transmitted from the VTU-R to the VTU-O in eoc messages upon request of the VTU-O. The VTU-O sends a data gathering command (to configure data gathering or to request a number of data gathering records, see Table 11-40.1). The VTU-R shall respond with a data gathering response (to ACK/NACK the data gathering configuration or to transfer data gathering records, see Table 11-40.2). The VTU-O shall acknowledge (ACK) the response and may simultaneously request more data gathering records. The VTU-R buffer shall be transferred to the VTU-O through a sequence of command and response messages until all records in the VTU-R buffer, up to *act\_logging\_depth\_reporting\_R* records, are reported. + +**Table 11-40.1 – Data gathering commands sent by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|--------------------------------|-----------------|----------------|-----------------------------------------------------------------------| +| Configure data gathering | | 2 | 00 16 | +| | | 3-4 | act_logging_depth_reporting_R | +| | | 5 | logging_reporting_newer_first | +| | | 6 | number of event types configured ( Ntyp ) | +| | | 7 | logging_depth_event_percentage_R_1 | +| | | ... | ... | +| | | 7+ Ntyp | logging_depth_event_percentage_R_Ntyp | +| Request data gathering records | 1 | 2 | 01 16 | +| | 1 | 3 | ACK_ID | +| | 1 | 4 | Sequence_ID | +| | 1 | 5 | Number of event records to report in response message ( Nreq ) | + +**Table 11-40.2 – Data gathering response sent by the VTU-R** + +| Name | Length (Octets) | Octet number | Content | +|--------------------------------------|-----------------------------------------------------------------|-----------------------------|-------------------------------------------------------------------------| +| Configure data gathering ACK | 4 | 4 | 80 16 | +| | | 5-6 | logging_depth_R | +| Configure data gathering NACK | 4 | 4 | 81 16 | +| | | 5-6 | logging_depth_R | +| Response with data gathering records | 10
(if Nreq =0)
up to 778
(if Nreq =128) | 2 | 90 16 | +| | | 3 | Sequence_ID | +| | | 4-7 | Current VTU-R timestamp | +| | | 8-9 | Number of event records in the buffer
not yet ACKed ( Nnack ) | +| | | 10 | Number of event records reported
in this message ( Nrep ) | +| | | 11 ...
10+6× Nrep | 6× Nrep octets with the data gathering records | + +##### 11.2.3.16.1 Data gathering configuration + +The control parameter *act\_logging\_depth\_reporting\_R* is defined in clause 11.5. The control parameter *logging\_report\_newer\_first* indicates the order in which the VTU-R shall report the records in the VTU-R buffer. If set to TRUE, then the VTU-R shall report the record related to the most recent event first. If set to FALSE, then the VTU-R shall report the record related to the least recent event first. The control parameter *logging\_report\_newer\_first* shall have a value equal to the CO-MIB configuration parameter LOGGING\_REPORT\_NEWER\_FIRST (see clause 7.3.6.5 of [ITU-T G.997.1]). + +The control parameters *logging\_depth\_event\_percentage\_Ri* are defined in clause 11.5. The *logging\_depth\_event\_percentage\_Ri* is configured for event type ID = 1 up to event type ID = *Ntyp*, with event type IDs as listed in Table 11-43. For all event types with ID > *Ntyp*, the VTU-R shall set *logging\_depth\_event\_percentage\_Ri* = 0. + +If the VTU-R supports the last received data gathering configuration, then the VTU-R shall send a configure data gathering ACK response. If the VTU-R does not support the last received data gathering configuration (e.g., because *act\_logging\_depth\_reporting\_R* is higher than *logging\_depth\_R*), then the VTU-R shall send a configure data gathering NACK response. Upon sending an ACK, the VTU-R shall apply the last received data gathering configuration. Upon receiving a NACK, the VTU-O shall send a new configure data gathering command. + +If a new data gathering configuration is applied with an *act\_logging\_depth\_reporting\_R* larger than or equal to the actual number of records in the VTU-R buffer, then existing records shall stay in the VTU-R buffer. Otherwise, the VTU-R may apply a vendor discretionary method (including reset of the entire VTU-R buffer) to discard records in the buffer. + +If a new data gathering configuration is applied with an *act\_logging\_depth\_reporting\_O* larger than or equal to the actual number of records in the VTU-O buffer, then existing records shall stay in the VTU-O buffer. Otherwise, the VTU-O may apply a vendor discretionary method (including reset of the entire VTU-O buffer) to discard records in the buffer. + +##### 11.2.3.16.2 Transfer of the VTU-R buffer from the VTU-R to the VTU-O + +The VTU-R buffer is transferred to the VTU-O through a sequence of command and response messages until all records in the VTU-R buffer, up to *act\_logging\_depth\_reporting\_R* records, are reported. + +The VTU-O allocates a sequence ID to each request data gathering records command message. The first command message in a sequence of command and response messages shall have Sequence\_ID = 0016. If the response message to a command message is received by the VTU-O, then the next command message shall have the Sequence\_ID incremented by one. If the response message to a command message is not received, then the next command message shall be a retransmission of the previous command message or a command message with sequence\_ID = 0016. If a sequence of more than 128 command and response messages is needed to transfer the whole VTU-R buffer, then the sequence\_ID following sequence\_ID = 7F16 shall be sequence\_ID = 0116. + +In the response with data gathering records message, the VTU-R shall copy the same sequence\_ID allocated by the VTU-O to the request data gathering records command message. + +In the command message with Sequence\_ID = 0016, the VTU-O shall set the ACK\_ID to 0016. + +When receiving a command message with Sequence\_ID = 0016, the VTU-R shall ignore the ACK\_ID in this command message. Before sending a response message, the VTU-R shall mark all records in the VTU-R buffer (except dummy records) as "not yet ACKed". In the response message (with Sequence\_ID = 0016), the value *Nnack* indicate the number of records in the VTU-R buffer. With a VTU-R buffer full condition, *Nnack* = *act\_logging\_depth\_reporting\_R*. + +When receiving a command message with $Sequence\_ID > 00_{16}$ , and before sending a response message, the VTU-R shall mark the set of records which were reported in the response message with $sequence\_ID$ equal to $ACK\_ID$ as having been ACKed. The VTU-R shall keep the ACKed records in the VTU-R buffer (i.e., not delete the ACKed records from the VTU-R buffer). + +NOTE 1 – The records are not marked as ACKed until the $ACK\_ID$ is received because eoc messages (requests or responses) can get lost. + +The command message shall include the number of records requested to be reported ( $Nreq$ ). The value of $Nreq$ shall be at most 128. If the VTU-O chooses to use multiple eoc command/response messages to transfer the whole VTU-R buffer, then the value of $Nreq$ may be less than *act\_logging\_depth\_reporting\_R*. + +The response message shall include the number of records stored in the VTU-R buffer that are not yet ACKed by the VTU-O ( $Nnack$ ), so the VTU-O knows how many more records are to be transferred. + +The response message shall include the number of records reported in the response message ( $Nrep$ ). The value $Nrep$ shall be the minimum of $Nreq$ and $Nnack$ . If $Nrep < Nreq$ , then $Nrep = Nnack$ . If all records in the VTU-R buffer have been ACKed, then $Nrep = Nnack = 0$ . + +If *logging\_report\_newer\_first* is FALSE, then the response message shall include the $Nrep$ least recent records in the VTU-R buffer that have not yet been ACKed by the VTU-O. The response message shall include the $Nrep$ records in ascending order of timestamp, with the least recent record starting at octet 11. + +If *logging\_report\_newer\_first* is TRUE, then the response message with $sequence\_ID = 0$ shall include the $Nrep$ most recent records in the VTU-R buffer that have not yet been ACKed by the VTU-O. The response messages with $sequence\_ID > 0$ shall include the $Nrep$ most recent records in the VTU-R buffer that have not yet been ACKed by the VTU-O and have a timestamp older than the timestamps of the records ACKed by the VTU-O in the command message. The response message shall include the $Nrep$ records in descending order of timestamp, with most recent record starting at octet 11. + +The response message includes the current VTU-R timestamp. This allows the VTU-O to offset all the VTU-R timestamps with a fixed offset so that they are stored in the CO-MIB in the same NTP format, with nearly the same timing, as the VTU-O timestamps. This also limits the time error due to VTU-R clock drift to the accumulated error between the time the event is recorded and the time that it is transferred to the VTU-O. + +Upon receiving the response message containing the last of *act\_logging\_depth\_reporting\_R* records to be transferred, or upon receiving a response message with $Nnack = Nrep$ , the VTU-O shall send the last command message in the sequence of command and response messages that is an acknowledgement of the last transferred $Nrep$ records, and has $Nreq = 0$ , denoting no further records are to be transferred. Only in this last command message in a sequence of command and response messages shall $Nreq = 0$ . All preceding command messages shall have $Nreq > 0$ . + +NOTE 2 – If no new records are generated at the VTU-R during the eoc transfer, then the entire VTU-R buffer is transferred to the VTU-O. + +NOTE 3 – If new event records are generated at the VTU-R during the eoc transfer, leading to already transferred records being removed from the VTU-R buffer due to buffer management rules, and *logging\_report\_newer\_first* is FALSE, then the VTU-R buffer will not be entirely transferred to the VTU-O because *act\_logging\_depth\_reporting\_R* records will have been ACKed by the VTU-O while $Nnack$ is still larger than zero at the VTU-R. + +NOTE 4 – If new event records are generated at the VTU-R during the eoc transfer, leading to not yet transferred records being removed from the VTU-R buffer due to buffer management rules, and *logging\_report\_newer\_first* is TRUE, then the VTU-R buffer will not be entirely transferred to the VTU-O + +because *Nnack* will be zero at the VTU-R before *act\_logging\_depth\_reporting\_R* records have been ACKed by the VTU-O. + +##### 11.2.3.16.3 Write of the transferred VTU-R buffer to the CO-MIB + +If *logging\_report\_newer\_first* is TRUE, then (see Notes 3, 4 and 5 below): + +- When the VTU-O sends a data gathering command message with *sequence\_ID* = 0016, the VTU-O shall reset the *EVENT\_TRACE\_BUFFER\_R* to all zero values by setting all records to be dummy records, where a dummy record is defined as a record which has all fields set to the value 0; +- The VTU-O shall write the block of records contained in the data gathering response message with *Sequence\_ID* = 0016 in the *EVENT\_TRACE\_BUFFER\_R* in the locations corresponding to the most recent block of records; +- The VTU-O shall write blocks of records contained in subsequent data gathering response messages in the *EVENT\_TRACE\_BUFFER\_R* in the locations corresponding to the next most recent block of records; +- The VTU-O may choose to update the *EVENT\_TRACE\_BUFFER\_R* with every received data gathering response message, or may choose to update after having received several data gathering response messages; + +NOTE 1 – Subsequent readings of the *EVENT\_TRACE\_BUFFER\_R* over the Q-interface while a transfer of the VTU-R buffer is ongoing may show a steadily increasing number of records in the CO-MIB element. + +- The order of the records in the *EVENT\_TRACE\_BUFFER\_R* shall correspond to the order of the records inside a received data gathering response message (i.e., no reordering inside a block), and concatenated in the order of subsequently received data gathering response messages (i.e., no reordering of blocks). + +If *logging\_report\_newer\_first* is FALSE, then (see Notes 4 and 5 below): + +- Then the VTU-O sends a data gathering command with *sequence\_ID* = 0016, then the *EVENT\_TRACE\_BUFFER\_R* is not reset; +- The VTU-O shall write the block of records contained in the data gathering response message with *Sequence\_ID* = 0016 in the *EVENT\_TRACE\_BUFFER\_R* in the locations corresponding to the least recent block of records and thereby overwrite the existing records at those locations; +- The VTU-O shall write blocks of records contained in subsequent data gathering response messages in the *EVENT\_TRACE\_BUFFER\_R* in the locations corresponding to the next least recent block of records and thereby overwrite the existing records at those locations; +- The VTU-O may choose to update the *EVENT\_TRACE\_BUFFER\_R* with every received data gathering response message, or may choose to update after having received several data gathering response messages; + +NOTE 2 – Subsequent readings of the *EVENT\_TRACE\_BUFFER\_R* over the Q-interface while a transfer of the VTU-R buffer is ongoing may show some duplicate records. + +- The order of the records in the *EVENT\_TRACE\_BUFFER\_R* shall correspond to the order of the records inside a received data gathering response message (i.e., no reordering inside a block), and concatenated in the order of subsequently received data gathering response messages (i.e., no reordering of blocks). + +NOTE 3 – Setting *logging\_report\_newer\_first* to TRUE allows the rapid transfer of a relatively small number of recent event records with a relatively small number of data gathering commands. + +NOTE 4 – If no new event records are generated at the VTU-R during the transfer of the VTU-R buffer, then the entire VTU-R buffer is transferred into *EVENT\_TRACE\_BUFFER\_R*. + +NOTE 5 – If new records are generated at the VTU-R during the transfer of the VTU-R buffer, then the CO-MIB parameter EVENT\_TRACE\_BUFFER\_R may not contain some records that are present in the VTU-R buffer at the end of the transfer, may not contain some records that were present in the VTU-R buffer at the start of the transfer, and may contain records that are not present in the VTU-R buffer at the end of the transfer because of buffer management. + +#### 11.2.3.17 SAVN-Update command and responses + +The VTU-O shall send the SAVN-Update command to communicate the updated value of the downstream transmitter referred showtime adaptive virtual noise (TXREFSAVNs) to the VTU-R. Upon reception of the SAVN-Update command, the VTU-R shall send a SAVN-Update response. + +The first octet of both the command and the response indicates the SAVN-Update command type, as defined in Table 11-4 (normal priority). The other octets of the SAVN-Update command are defined in Table 11-40.3. The SAVN-Update response shall be a simple acknowledgement that indicates the serial number of the update, as defined in Table 11-40.4. The SAVN-Update command shall be initiated by the VTU-O only. The SAVN-Update response shall be sent by the VTU-R only. + +**Table 11-40.3 – SAVN-Update command (sent by the VTU-O)** + +| Name | Length (Octets) | Octet number | Content | +|-------------|----------------------------------------------------------------------|-------------------------------------------------------------------------|-----------------------------------------------------------------| +| SAVN-Update | 7+(stop sub-carrier group index – start sub-carrier group index + 1) | 2 | 09 16 (Note 1) | +| | | 3 | One octet containing the sequence number of the update (Note 2) | +| | | 4 to 5 | 2 octets describing the start subcarrier group index | +| | | 6 to 7 | 2 octets describing the stop subcarrier group index | +| | | 8 to 7+(stop subcarrier group index – start subcarrier group index + 1) | The transmitter-referred SAVN PSD, TXREFSAVNs | + +NOTE 1 – All other values for octet numbers 2 are reserved by ITU-T. + +NOTE 2 – The sequence number of the update shall be "1" for the first SAVN-Update command, and shall be incremented by 1 for each subsequent SAVN-Update command, wrapping around to "0" after "255". + +TXREFSAVNs indicates the PSD of the SAVN that shall be taken into account when determining bit loading and active tone set using SNRM\_MODE = 5 (see clause 11.4.1.1.6.1.5). In case SAVN is not used, both the start subcarrier group index and the stop subcarrier group index shall be equal to 0 and the TXREFSAVNs field shall be of zero length. + +TXREFSAVNs( $k \times G \times \Delta f$ ) shall be the value of the transmitter referred SAVN PSD for subcarriers with indices from $k \times G$ to $((k+1) \times G) - 1$ , inclusive. It shall be represented as an 8 bit unsigned integer *savn(k)*, where $k = 0$ to 511. The value of TXREFSAVNs( $k \times G \times \Delta f$ ) shall be defined as $TXREFSAVNs(k \times G \times \Delta f) = -23 - (savn(k)/2)$ dBm/Hz. This data format supports a TXREFSAVNs(*f*) granularity of 0.5 dB with a valid range of values for TXREFSAVNs(*f*) from –150 (coded 254) to –23 (coded 0) dBm/Hz. The value coded 255 is reserved for future use by ITU-T. + +The group size for TXREFSAVNs shall be $G = 8$ . + +**Table 11-40.4 – SAVN-Update response (sent by the VTU-R)** + +| Name | Length (Octets) | Octet number | Content | +|-----------------------------------------------------------------|-----------------|--------------|---------------------------------------------------------------------------------------------------------------------------------------------| +| SAVN-ACK | 4 | 2 | 0A 16 (Note 1) | +| | | 3 | One octet containing the sequence number of the acknowledged SAVN-Update command | +| | | 4 | One octet indicating whether or not an SRA will follow (Note 1):
00 16 SRA will follow
01 16 No SRA will follow | +| SAVN-NACK | 3 | 2 | 0B 16 (Note 1) | +| | | 3 | Reason code (Note 1):
00 16 Invalid parameter set
01 16 Violation of initialization policy | +| NOTE 1 – All other values for this octet are reserved by ITU-T. | | | | + +The VTU-R shall compute the bit loading and framing parameters corresponding to the updated value of the TXREFSAVNs. The updated value of TXREFSAVNs may require a modification of the bit loading, or framing parameters, or both, with the aim of maintaining operation of the line within the boundaries set at initialization (e.g., SNRM boundaries). If no modification of the bit loading, or framing parameters is required, then the VTU-R shall reply with the SAVN-ACK response, indicating no SRA will follow. If modification of the bit loading or framing parameters is required and the required modification of the bit loading or framing parameters is within the boundaries set at initialization (e.g., related to ETR), then the VTU-R shall reply with the SAVN-ACK response indicating an SRA will follow and shall initiate an SRA (Request Type 3 for ITU-T G.993.2 and Request Type 5 for ITU-T G.998.4) within 1 second after sending the SAVN-ACK response. If the required modification cannot be made within the boundaries set at initialization (e.g., related to ETR), then the VTU-R shall reply with the SAVN-NACK response using a reason code 0116, which means that the requested SAVN PSD cannot be applied within the initialization policy. + +Upon receiving a SAVN-NACK response, the VTU-O may either send another SAVN PSD update or re-initialize the line with new boundaries for performance parameters, which can fit the required SAVN settings. + +VTU-O shall not send SAVN-Update command when the VTU-R is involved in an OLR procedure associated with change of the bit loading or framing parameters in the downstream direction. + +### 11.2.4 Indicator bits (IB) + +The IB are used to send the far-end anomalies and defects specified in Table 11-41. Sending IB is mandatory, both upstream and downstream. The IB shall be set to ZERO if in the active state. Mapping of the IB to the overhead channel shall be as specified in clause 9.5.2.2. + +**Table 11-41 – Content of IB** + +| IB | Description | Reference | +|--------------------|---------------------------------------------------------------|---------------------| +| los | Loss of signal defect | See clause 11.3.1.3 | +| rdi | Remote defect indication defect | See clause 11.3.1.4 | +| lpr | Loss of power primitive | See clause 11.3.3.1 | +| TIB#0-1 to TIB#0-4 | Four indicator bits reserved for the TPS-TC serving bearer #0 | See Annex L | +| TIB#1-1 to TIB#1-4 | Four indicator bits reserved for the TPS-TC serving bearer #1 | See Annex L | + +## 11.3 OAM primitives + +Among the standard OAM primitives, this Recommendation specifies only anomalies and defects. The system shall use the corresponding failure specifications of [ITU-T G.997.1]. + +Both the near-end and the far-end primitives shall be represented at the VTU-O; representation of the far-end anomalies and defects at the VTU-R is optional. + +OAM primitives shall not be generated for the overhead-only latency path (ROC). + +### 11.3.1 Line-related primitives + +Line-related primitives represent anomalies, defects, and other primitives related to PMD and PMS-TC sublayers. + +#### 11.3.1.1 Near-end anomalies + +- Forward error correction (*fec-p*): This anomaly occurs when a received FEC codeword in the latency path *#p* indicates that errors have been corrected. This anomaly is not asserted if errors are detected and are not correctable. +- Cyclic redundancy check (*crc-p*): This anomaly occurs when a received CRC byte for the latency path *#p* is not identical to the corresponding locally generated CRC byte. +- Rate adaptation upshift (*rau*): For further study. +- Rate adaptation downshift (*rad*): For further study. +- Loss-of-power interruption (*lpr\_intrpt*): Excluding re-initializations triggered by the VTU-O host, this anomaly occurs upon entry into showtime when at least one of the following conditions is met: + - a far-end loss-of-power (*flpr*) primitive was declared before the exit from showtime; or + - the PLPR flag (retrieved from the VTU-R) is set to ONE at the entry into showtime (see clause 11.2.3.6). + +This anomaly is only defined at the VTU-O; + +- Host-Reinit interruption (*hri\_intrpt*): Excluding re-initializations triggered by the VTU-O host, this anomaly occurs upon entry into showtime when the PHRI flag (retrieved from the VTU-R) is set to ONE at the entry into Showtime (see clause 11.2.3.6). + +This anomaly is only defined at the VTU-O. + +- Spontaneous interruption (*spont\_intrpt*): Excluding re-initializations triggered by the VTU-O host, this anomaly occurs upon entry into showtime after a successful full initialization, if the following conditions are met: + - the time between the exit from showtime of the VTU-O and the first successful reception of a [ITU-T G.994.1] message is less than 23 seconds; and + +- neither an *lpr\_intrpt* anomaly nor an *hri\_intrpt* anomaly occurs at the entry into showtime. + +The PLPR flag and the PHRI flag are optional at the VTU-R. If not supported by the VTU-R, then the VTU-O shall consider these flags as set to ZERO. + +This anomaly is only defined at the VTU-O. + +#### 11.3.1.2 Far-end anomalies + +- Far-end forward error correction (*ffec-p*): This anomaly occurs when an *fec-p* anomaly detected at the far end is reported. This anomaly terminates when the received report on the *fec-p* anomaly is terminated. +- Far-end block error (*febe-p*): This anomaly occurs when a *crc-p* anomaly detected at the far end is reported. This anomaly terminates when the received report on the *crc-p* anomaly is terminated. + +#### 11.3.1.3 Near-end defects + +- Loss of signal (*los*): A reference power is established by averaging the VDSL2 receive power over a 0.1 s period and over a subset of subcarriers used for Showtime, and a threshold shall be set 6 dB below this level. An *los* occurs when the level of the VDSL2 receive power averaged over a 0.1 s period and over the same subset of subcarriers is lower than the threshold, and terminates when this level, measured in the same way, is at or above the threshold. The subset of subcarriers is implementation dependent. +- Severely errored frame (*sef*): This defect occurs when the content of two consecutively received sync symbols does not correlate with the expected content over a subset of the subcarriers. An *sef* terminates when the content of two consecutively received sync symbols correlates with the expected content over the same subset of the subcarriers. The correlation method, the selected subset of subcarriers, and the threshold for declaring these defect conditions are vendor discretionary. +- Loss of margin (*lom*): This defect occurs when the signal-to-noise ratio margin (SNRM), see clause 11.4.1.1.6, observed by the near-end receiver is below the minimum signal-to-noise ratio margin (MINSNRM, see clause 12.3.5.2.1.1) and an increase of SNRM is no longer possible within the far-end aggregate transmit power and transmit PSD level constraints. This defect terminates when the SNRM is above the MINSNRM. The SNRM measurement update rate shall be at least once every 5 seconds. + +#### 11.3.1.4 Far-end defects + +- Far-end loss of signal (*los-fe*): This defect occurs when an *los* detected at the far end is reported in at least 4 of 6 consecutively received far-end *los* indicator reports. An *los-fe* terminates when fewer than two far-end *los* indicators are reported out of 6 consecutively received reports. +- Remote defect indication (*rdi*): This defect occurs when an *sef* detected at the far end is reported. An *rdi* terminates when the received report on *sef* is terminated, i.e., when the value of the corresponding IB is reset to ONE. +- Far-end loss of margin (*lom-fe*): This defect occurs when the SNRM, see clause 11.4.1.1.6, at the far-end receiver, retrieved by the near-end transmitter is below the minimum signal-to-noise ratio margin (MINSNRM, see clause 12.3.5.2.1.1) and an increase of SNRM is no longer possible within the near-end aggregate transmit power and transmit PSD level constraints. This defect terminates when the SNRM is above the MINSNRM. + +#### 11.3.1.5 Near-end OLR primitives + +Successful SOS (*success\_SOS*): This primitive occurs each time a successful SOS procedure is performed through the near-end initiating an OLR type 4 or 6 for SOS (see Table 11-6 and clause 12.1.4). + +Successful autonomous SRA (*success\_SRA*): This primitive occurs each time the bit loading on the data symbols is changed through the SRA initiated by the near-end (using Request Type 3, see Table 11-6). + +#### 11.3.1.6 Far-end OLR primitives + +Successful SOS (*success\_SOS-fe*): This primitive occurs each time a successful SOS procedure is performed through the far-end initiating an OLR type 4 or 6 for SOS (see Table 11-6 and clause 12.1.4). + +Successful autonomous SRA (*success\_SRA\_FE*): This primitive occurs each time the bit loading on the data symbols is changed through the SRA initiated by the far-end (using Request Type 3, see Table 11-6). + +### 11.3.2 Path-related primitives + +Path-related primitives are defined separately for each path, terminated by the corresponding TPS-TC. The primitives for each TPS-TC (ATM, PTM, STM, etc.) shall be represented by relevant OAM indicators specified for this protocol. + +#### 11.3.2.1 Anomalies and defects for ATM transport + +The specified set of anomalies and defects for the ATM transport shall be supported by the ATM-TC. In the case of multiple bearer channels, the corresponding ATM-TCs shall be represented by independent sets of indicators. The anomalies and defect indicators shall comply with clause L.2. + +#### 11.3.2.2 Anomalies and defects for STM transport + +The specified set of anomalies and defects for the STM transport shall be supported by the STM-TC. In the case of multiple bearer channels, the corresponding STM-TCs shall be represented by independent sets of indicators. The anomalies and defect indicators shall comply with clause L.1. + +#### 11.3.2.3 Anomalies and defects for PTM transport + +The anomalies and defects for the PTM transport shall be supported by the PTM-TC. In the case of multiple bearer channels, the corresponding PTM-TCs shall be represented by independent sets of indicators. The anomalies and defect indicators shall comply with clause L.3. + +### 11.3.3 Power-related primitives + +### 11.3.3.1 Near-end primitives + +Loss of power (*lpr*): This primitive occurs when the VTU power supply (mains) voltage drops below the manufacturer-determined level required for proper VTU operation. An *lpr* terminates when the power level exceeds the manufacturer-determined minimum power level. + +### 11.3.3.2 Far-end primitives + +Far-end loss of power (*flpr*): This primitive detected at the far end is reported by the *flpr* indicator, which shall be coded 1 to indicate that no *lpr* is being reported and shall be coded 0 for the next 3 *lpr* indicator transmissions to indicate that an *flpr* (i.e., "dying gasp") is being reported. An *flpr* occurs when 2 or more out of 3 consecutively received *lpr* indicators are set to ZERO. An *flpr* terminates when, for a period of 0.5 seconds, the received *lpr* indicator bit is set to ONE and no near-end *los* is present. + +### 11.3.4 INM primitives + +INM-related primitives represent anomalies related to PMD and PMS-TC sublayers. + +#### 11.3.4.1 INM INPEQ histogram primitives + +If INM\_INPEQ\_FORMAT=0, then the INM INPEQ histogram shall be configured with a linear scale as follows: + +- INMAINPEQ1..INMAINPEQ16: every INMAINPEQi is a primitive detected at the near-end only. This anomaly occurs when the equivalent INP (as defined in clause 11.4.2.2.1) is exactly *i* DMT symbols; +- INMAINPEQ17 is a primitive detected at the near-end only. This anomaly occurs when the equivalent INP (as defined in clause 11.4.2.2.1) is strictly more than 16 DMT symbols. + +If INM\_INPEQ\_FORMAT=1 then the INM INPEQ histogram shall be configured with a logarithmic scale as follows ( $\lfloor x \rfloor$ denotes rounding to the lower integer): + +- INMAINPEQ1..INMAINPEQ16: every INMAINPEQi is a primitive detected at the near-end only. This anomaly occurs when the equivalent INP (as defined in clause 11.4.2.2.1) falls in the range from $\lfloor 1.33^{i+1} \rfloor$ to $\lfloor 1.33^{i+2} \rfloor - 1$ DMT symbols, both boundaries inclusive; +- INMAINPEQ17 is a primitive detected at the near-end only. This anomaly occurs when the equivalent INP (as defined in clause 11.4.2.2.1) is at least $\lfloor 1.33^{17+1} \rfloor = 169$ DMT symbols. + +NOTE – The logarithmic scale gives rise to the following possible INMAINPEQ histogram ranges (in DMT symbols). It gives a finer granularity for the higher probability short duration impulses, whilst still capturing some information about the longer duration events. + +| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | +|----------|----------|----------|----------|----------|----------|-----------|------------|------------|------------|------------|------------|------------|------------|-------------|--------------|----------| +| 1 –
1 | 2 –
2 | 3 –
3 | 4 –
4 | 5 –
6 | 7 –
8 | 9 –
12 | 13 –
16 | 17 –
22 | 23 –
29 | 30 –
39 | 40 –
53 | 54 –
71 | 72 –
94 | 95 –
126 | 127 –
168 | ≥
169 | + +#### 11.3.4.2 INM total measurement primitive + +- INMAME: is a primitive detected at the near-end only. This indication occurs every time a data symbol is processed by the impulse noise sensor (INS). + +#### 11.3.4.3 INM inter-arrival time histogram primitives + +- INMAIAT0 is a primitive detected at the near-end only. This anomaly occurs when the reported value of IAT falls in the range from 2 to INMIATO-1, both boundaries inclusive; +- INMAIAT1..INMAIAT6: every INMAIATi is a primitive detected at the near-end only. This anomaly occurs when the reported value of IAT falls in the range from (INMIATO + (i – 1) × (2INMIATS)) to (INMIATO – 1) + i × (2INMIATS), both boundaries inclusive; +- INMAIAT7 is a primitive detected at the near-end only. This anomaly occurs when the reported value of IAT falls in the range from INMIATO + 6 × (2INMIATS) to infinity. + +### 11.4 OAM parameters + +The system may support and use the relevant OAM parameters for the VTU-O and VTU-R, as specified in clauses 7.2 and 7.3 of [ITU-T G.997.1]. Specifically, these are: + +- Line-related and Path-related performance parameters; +- Line-related and Path-related configuration parameters; and +- Inventory parameters. + +Test parameters shall be computed and formatted as specified in clause 11.4.1 to be reported in the format specified in [ITU-T G.997.1]. + +### 11.4.1 Test parameters + +The test parameters are measured by the PMD transmit or receive function and shall be reported on request to the near-end VME. Test parameters can be used to identify possible issues with the physical loop and to check for adequate physical media performance margin at acceptance and after repair verification, or at any other time following the initialization of the VDSL2 system. + +The following test parameters shall be passed on request from the receive PMD function to the near-end VME: + +- Channel characteristics function $H(f)$ per subcarrier (CCF-ps); +- Quiet line noise PSD $QLN(f)$ per subcarrier (QLN-ps); +- Signal-to-noise Ratio $SNR(f)$ per subcarrier (SNR-ps); +- Loop attenuation per band (LATN-pb); +- Signal attenuation per band (SATN-pb); +- Signal-to-noise ratio margin per band (SNRM-pb); +- Signal-to-noise ratio margin for the ROC (SNRM-ROC); +- Attainable net data rate (ATTNDR); +- Far-end actual aggregate transmit power (ACTATP); +- Far-end actual impulse noise protection (INP\_act); and +- Far-end actual impulse noise protection of the ROC (INP\_act-ROC). + +The following test parameter shall be passed on request from the transmit PMD function to the near-end VME: + +- Near-end actual aggregate transmit power (ACTATP). + +The purposes of making the above information available are: + +- $H(f)$ can be used to analyse the physical copper loop condition; +- $QLN(f)$ can be used to analyse the crosstalk; +- $SNR(f)$ can be used to analyse time-dependent changes in crosstalk levels and loop attenuation (such as due to moisture and temperature variations); and +- The combination of $H(f)$ , $QLN(f)$ and $SNR(f)$ can be used to help determine why the data rate is not equal to the maximum data rate for a given loop. + +The detailed diagnostic information $H(f)$ and $QLN(f)$ would be most useful during showtime. However, requesting this would place an undue computational burden on the VTUs. Thus, the combination of complete information on the channel ( $H(f)$ and $QLN(f)$ ) during initialization combined with initialization and showtime $SNR(f)$ is provided as a reasonable compromise. This combination of data will allow greater analysis of the loop conditions than traditional methods and will reduce interruptions to both VDSL2 and the underlying service that traditional diagnostic methods require. + +The quiet line noise (QLN), signal-to-noise ratio (SNR), and channel characteristics in format (Hlin, Hlog) shall be represented by subcarrier groups. The number of subcarriers, $G$ , in one subcarrier group shall be equal to: + +$$G = pow2(\Theta/512)$$ + +where the function $pow2(x)$ takes the nearest power of 2 greater than or equal to $x$ and $\Theta$ is the highest subcarrier index of the transmitter SUPPORTEDCARRIERS set if the parameter is measured during the channel discovery phase; or the last subcarrier index of the transmitter MEDLEY set in other cases. + +Specific carrier sets to be used during showtime and loop diagnostic mode are summarized in Table 11-42 (N/A indicates that a parameter is not applicable). + +**Table 11-42 – Value of $G$ for various phases of operation** + +| Test parameter | Normal operation | Loop diagnostic mode | | +|----------------|-------------------|----------------------|-------------------------------| +| | Showtime | Channel discovery | Channel analysis and exchange | +| QLN | SUPPORTEDCARRIERS | SUPPORTEDCARRIERS | N/A | +| HLOG | SUPPORTEDCARRIERS | SUPPORTEDCARRIERS | N/A | +| HLIN | N/A | N/A | MEDLEY | +| SNR | MEDLEY | N/A | MEDLEY | + +Valid values of $G$ are 1, 2, 4 and 8. + +#### 11.4.1.1 Definition of test parameters + +##### 11.4.1.1.1 Channel characteristics function per subcarrier group (CCF-ps) + +The channel characteristics function $H(f)$ is a quantity that is related to the values of the (complex) source and load impedances. A simplified definition is used in which the source and load impedances are the same and equal to a real value $R_N$ . The channel characteristics function $H(f)$ is associated with a two-port network, normalized to a chosen reference resistance $R_N$ . $H(f)$ shall be defined as a complex value, equal to the $U_2/U_1$ voltage ratio (see Figures 11-3 and 11-4). + +![Figure 11-3: Circuit diagram showing a voltage source connected in series with a resistor R_N. This is connected to a two-port network (represented by a box). The output of the two-port network is connected to a load resistor R_N. The voltage across the load resistor is labeled U1. The diagram is labeled G.993.2_F11-3.](ff722ae9516b94709d721deaf5523d2e_img.jpg) + +Figure 11-3: Circuit diagram showing a voltage source connected in series with a resistor R\_N. This is connected to a two-port network (represented by a box). The output of the two-port network is connected to a load resistor R\_N. The voltage across the load resistor is labeled U1. The diagram is labeled G.993.2\_F11-3. + +**Figure 11-3 – Voltage across the load** + +![Figure 11-4: Circuit diagram showing a voltage source connected in series with a resistor R_N. This is connected to a two-port network (represented by a box). The output of the two-port network is connected to a load resistor R_N. The voltage across the load resistor is labeled U2. The diagram is labeled G.993.2_F11-4.](8792c5728b4e100e0a00432bbfcab87b_img.jpg) + +Figure 11-4: Circuit diagram showing a voltage source connected in series with a resistor R\_N. This is connected to a two-port network (represented by a box). The output of the two-port network is connected to a load resistor R\_N. The voltage across the load resistor is labeled U2. The diagram is labeled G.993.2\_F11-4. + +**Figure 11-4 – Voltage across the load with a two-port network inserted** + +The measurement of a channel characteristics function is the result of the cascade of three functions: + +- 1) The transmitter filter characteristics function; +- 2) The channel characteristics function; and +- 3) The receiver filter characteristics function. + +NOTE – The channel characteristics function corresponds to the $H_{\text{channel}}(f)$ function used in the definition of the far-end crosstalk (see clause 7.4.1 of [ITU-T G.996.1]). + +The objective is to provide means by which the channel characteristics can be accurately identified. Therefore, it is necessary for the receive PMD function to report an estimate of the channel characteristics. This task may prove to be a difficult one given the fact that the receive PMD function only observes the cascade of all three elements of the channel. The passband part of the reported $H(f)$ , which is most essential to debug possible issues with the physical loop, is not expected to significantly depend upon the receiver filter characteristics (not including receiver automatic gain control (AGC)). The receive PMD function shall therefore invert the gain (AGC) it has applied to the received signal and do a best effort attempt to remove the impact of the near-end receiver filter characteristics. The result is then a best estimate of how the receiver views the passband channel characteristics plus the transmitter filter characteristics. Because the in-band portion of the spectrum is also expected not to significantly depend upon the transmitter filter characteristics, this result is considered a sufficient estimate of the channel characteristics for desired loop conditioning applications. + +Two formats for the channel characteristics are defined: + +- $Hlin(f)$ : a format providing complex values on a linear scale; and +- $Hlog(f)$ : a format providing magnitude values on a base 10 logarithmic scale. + +For $Hlog(f)$ , the receive PMD function shall also use the value of the PSD at the U interface of the transmit PMD function (as conveyed in messages during initialization) to remove the impact of the far-end transmit filter characteristics. + +For $Hlin(f)$ , if the channel characteristics are reported over the VTU-O OAM interface (see Figure 5-3), the VTU-O shall do a best effort attempt to remove the impact of the near-end transmit filter characteristics from the channel characteristics measured at the VTU-R. If the channel characteristics are reported over the VTU-R OAM interface, the VTU-R shall do a best effort attempt to remove the impact of the near-end transmit filter characteristics from the channel characteristics measured at the VTU-O. + +$Hlin(f)$ shall be sent to the far-end VME during the loop diagnostic mode and shall be sent on request to the near-end VME during the loop diagnostic mode. + +$Hlog(f)$ shall be measured by the receive PMD function during the loop diagnostic mode and initialization. The measurement shall not be updated during showtime. $Hlog(f)$ shall be sent to the far-end VME during the loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send $Hlog(f)$ to the far-end VME on request during showtime. + +In loop diagnostic mode, both $Hlin(f)$ and $Hlog(f)$ shall be measured, because the corrections that can be done, relative to the receiver and/or transmitter filter characteristics with $Hlin(f)$ and $Hlog(f)$ , may differ. + +$Hlin(f)$ and $Hlog(f)$ shall be measured over a 1 second time period in loop diagnostic mode. In initialization, the VTU should do its best to optimize the accuracy of the $Hlog(f)$ measurement; however, it shall measure at least 256 symbols, and shall indicate the measurement period (in symbols, represented as a 16-bit unsigned value) to the far-end VME (see clause 11.2.3.11). + +The channel characteristics function $Hlin(k \times G \times \Delta f)$ shall be the value of the channel characteristics on the subcarrier $i = k \times G$ . It shall be represented in linear format by a scale factor and a normalized complex number $a(k) + j \times b(k)$ , $k = 0$ to 511. The scale factor shall be coded as a 16-bit unsigned integer. Both $a(k)$ and $b(k)$ shall be coded as 16-bit twos complement signed integers. The value of $Hlin(k \times G \times \Delta f)$ shall be defined as: + +$$Hlin(k \times G \times \Delta f) = (scale/2^{15}) \times (a(k) + j \times b(k))/2^{15}$$ + +In order to maximize precision, the scale factor, $scale$ , shall be chosen such that $\max(|a(k)|, |b(k)|)$ over all $k$ is equal to $2^{15} - 1$ . + +This data format supports an $Hlin(f)$ granularity of $2^{-15}$ and an $Hlin(f)$ dynamic range of approximately 96 dB (+6 dB to -90 dB). The portion of the scale factor range above 0 dB is necessary because, due to manufacturing variations in signal path gains and filter responses, short loops may appear to have a gain rather than a loss. + +An $\text{Hlin}(k \times G \times \Delta f)$ value indicated as $a(k) = b(k) = -2^{15}$ is a special value. It indicates that: + +- no measurement could be done for this subcarrier because it is out of the transmitter MEDLEY set or its $g_i = 0$ ; or +- the attenuation is out of the range to be represented. + +The channel characteristics function $\text{Hlog}(k \times G \times \Delta f)$ shall be the magnitude of the channel characteristics at subcarrier $k \times G$ . It shall be represented in base 10 logarithmic format by an integer number $m(k)$ , where $k = 0$ to 511. The $m(k)$ shall be coded as 10-bit unsigned integers. The value of $\text{Hlog}(k \times G \times \Delta f)$ shall be defined as: + +$$\text{Hlog}(k \times G \times \Delta f) = 6 - (m(k)/10)$$ + +This data format supports an $\text{Hlog}(f)$ granularity of 0.1 dB and an $\text{Hlog}(f)$ dynamic range of approximately 102 dB (+6 dB to -96 dB). + +An $\text{Hlog}(k \times G \times \Delta f)$ value indicated as $m(k) = 2^{10} - 1$ is a special value. It indicates: + +- that no measurement could be done for this subcarrier because it is out of the transmitter SUPPORTEDCARRIERS set; or +- that the attenuation is out of the range to be represented. + +#### 11.4.1.1.2 Quiet line noise PSD per subcarrier group (QLN-ps) + +The quiet line noise PSD $\text{QLN}(f)$ for a particular subcarrier is the rms level of the noise present on the loop when no VDSL2 signals are present on the loop. The received virtual noise PSD as defined in SNRM\_MODE=2, SNRM\_MODE=3, SNRM\_MODE=4, and SNRM\_MODE=5 shall not be taken into account in $\text{QLN}(f)$ . + +The quiet line noise PSD $\text{QLN}(f)$ per subcarrier shall be measured by the receive PMD function during loop diagnostic mode and initialization. The measurement shall not (i.e., cannot) be updated during showtime. The $\text{QLN}(f)$ shall be sent to the far-end VME during loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the $\text{QLN}(f)$ to the far-end VME on request during showtime. + +The objective is to provide means by which the quiet line noise PSD can be accurately identified. Therefore, it would be necessary for the receive PMD function to report an estimate of the quiet line noise PSD. This task may prove to be a difficult one given the fact that the receive PMD function observes the noise through the receiver filter. The passband part of the reported QLN-ps, which is most essential to debug possible issues with the physical loop, is not expected to significantly depend upon the receiver filter characteristics (not including receiver AGC). The receive PMD function shall therefore invert the gain (AGC) it has applied to the received signal and do a best effort attempt to remove the impact of the near-end receiver filter characteristics. The result is then a best estimate of how the receiver views the passband quiet line noise PSD. This result is considered a sufficient estimate of the quiet line noise PSD for desired loop conditioning applications. + +The receive PMD function shall measure the $\text{QLN}(f)$ in a time interval when no VDSL2 signals are present on the loop (i.e., the near-end and far-end transmitters are inactive). The quiet line noise PSD $\text{QLN}(i \times \Delta f)$ shall be measured over a 1 second time interval in loop diagnostic mode. In initialization, the VTU should do its best to optimize the accuracy of the $\text{QLN}(f)$ measurement, however, it shall measure over at least 256 symbols, and shall indicate the measurement period (in symbols, represented as a 16-bit unsigned value) to the far-end VME (see clause 11.2.3.11). + +The quiet line noise PSD $\text{QLN}(k \times G \times \Delta f)$ shall be the average of the power values of quiet line noise on the subcarriers $k \times G$ to $((k+1) \times G) - 1$ . It shall be represented as an 8-bit unsigned integer $n(k)$ , where $k = 0$ to 511. The value of $\text{QLN}(k \times G \times \Delta f)$ shall be defined as $\text{QLN}(k \times G \times \Delta f) = -23 - (n(k)/2)$ dBm/Hz. This data format supports a $\text{QLN}(f)$ granularity of 0.5 dB with a range of values for $\text{QLN}(f)$ from -150 to -23 dBm/Hz. + +A QLN( $k \times G \times \Delta f$ ) value indicated as $n(k) = 255$ is a special value. It indicates that: + +- no measurement could be done for this subcarrier group because one of its subcarriers is out of the transmitter SUPPORTEDCARRIERS set; or +- the quiet line noise PSD is out of the range to be represented. + +#### 11.4.1.1.3 Signal-to-noise ratio per subcarrier group (SNR-ps) + +The signal-to-noise ratio $\text{SNR}(f)$ for a particular subcarrier is a real value that shall represent the ratio between the received signal power and the received noise power for that subcarrier. The received virtual noise PSD as defined in SNRM\_MODE=2, SNRM\_MODE=3, and SNRM\_MODE=4 shall not be taken into account in $\text{SNR}(f)$ . + +The signal-to-noise ratio $\text{SNR}(f)$ per subcarrier shall be measured by the receive PMD function in loop diagnostic mode and initialization. The measurement may be updated autonomously and shall be updated on request during showtime. The $\text{SNR}(f)$ shall be sent to the far-end VME during loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the $\text{SNR}(f)$ to the far-end VME on request during showtime. + +The receive PMD function shall measure the signal-to-noise ratio $\text{SNR}(f)$ with the transmit PMD function in a MEDLEY or showtime state. The signal-to-noise ratio $\text{SNR}(f)$ shall be measured over a 1 second time interval in loop diagnostic mode. In initialization and showtime, the VTU should do its best to minimize the $\text{SNR}(f)$ measurement time, however it shall measure over at least 256 symbols, and it shall indicate the measurement period (in symbols, represented as a 16-bit unsigned value) to the far-end VME (see clause 11.2.3.11). + +The signal-to-noise ratio $\text{SNR}(k \times G \times \Delta f)$ shall be the average of the base 10 logarithmic value of the signal-to-noise ratio on the subcarriers $k \times G$ to $((k+1) \times G) - 1$ . It shall be represented as an 8-bit unsigned integer $\text{snr}(k)$ , where $k = 0$ to 511. The value of $\text{SNR}(k \times G \times \Delta f)$ shall be defined as $\text{SNR}(k \times G \times \Delta f) = -32 + (\text{snr}(k)/2)$ dB. This data format supports an $\text{SNR}(k \times G \times \Delta f)$ granularity of 0.5 dB and an $\text{SNR}(k \times G \times \Delta f)$ dynamic range of 127 dB (-32 to 95 dB). + +An $\text{SNR}(k \times G \times \Delta f)$ value indicated as $\text{snr}(k) = 255$ is a special value. It indicates that: + +- no measurement could be done for this subcarrier group because one of its subcarriers is out of the transmitter MEDLEY set or its $g_i = 0$ ; or +- the signal-to-noise ratio is out of the range to be represented. + +#### 11.4.1.1.4 Loop attenuation per band (LATN-pb) + +The loop attenuation in the $m^{\text{th}}$ downstream band is denoted as LATN\_D( $m$ ), and the loop attenuation in the $m^{\text{th}}$ upstream band is denoted as LATN\_U( $m$ ). For ease of notation, this clause provides requirements and definitions in terms of the downstream loop attenuation, but the same definitions and requirements also apply to LATN\_U( $m$ ). + +The loop attenuation of the $m^{\text{th}}$ downstream band (LATN\_D( $m$ )) is the squared magnitude of the channel characteristics function $H(f)$ (as defined in clause 11.4.1.1.1) averaged over all subcarriers of the $m^{\text{th}}$ downstream band, converted to dB. LATN\_D( $m$ ) shall be defined as: + +$$\text{LATN\_D}(m) = -10 \times \log_{10} \left( \frac{\sum_{i=n1}^{n2} |H(i \times \Delta f)|^2}{N\_D(m)} \right)$$ + +with $N\_D(m)$ (the number of subcarriers in the $m^{\text{th}}$ downstream band) = $n2 - n1 + 1$ where $n1$ and $n2$ are the indices of the first and the last subcarriers of this band, respectively, and $H(f)$ is represented by Hlin( $f$ ) in loop diagnostic mode and by Hlog( $f$ ) in initialization (with conversion of $\log_{10}$ to linear values for use in the above equation). + +If one or more $H(f)$ values could not be measured because they are out of the transmitter SUPPORTEDCARRIERS set (see clause 11.4.1.1.1), then the $LATN\_D(m)$ shall be calculated as an average of $H(f)$ values over the number of subcarriers for which valid values of $H(f)$ are available. + +The loop attenuation shall be calculated by the receive PMD function during loop diagnostic mode and initialization. The calculation shall not be updated during showtime. The loop attenuation shall be sent to the far-end VME during initialization and loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the $LATN$ to the far-end VME on request during showtime. + +The loop attenuation per downstream band $LATN\_D(m)$ shall be represented as a 10-bit unsigned integer *latn*, with the value of $LATN\_D(m)$ defined as $LATN\_D(m) = latn/10$ dB. This data format supports a $LATN\_D(m)$ granularity of 0.1 dB and an $LATN\_D(m)$ dynamic range of 102.2 dB (0 to 102.2 dB). + +A $LATN\_D(m)$ value indicated as *latn* = 1023 is a special value. It indicates that the loop attenuation is out of the range that can be represented. + +#### 11.4.1.1.5 Signal attenuation per band (SATN-pb) + +The signal attenuation in the $m^{\text{th}}$ downstream band is denoted as $SATN\_D(m)$ , and the signal attenuation in the $m^{\text{th}}$ upstream band is denoted as $SATN\_U(m)$ . For ease of notation, this clause provides requirements and definitions in terms of the downstream signal attenuation, but the same definitions and requirements also apply to $SATN\_U(m)$ . + +The signal attenuation of the $m^{\text{th}}$ downstream band, $SATN\_D(m)$ , is defined as the difference in dB between the power received at the near-end and that transmitted from the far end in the $m^{\text{th}}$ downstream band. + +Mathematically, this corresponds to: + +$$SATN\_D(m) = TXpower\_dBm\_D(m) - RXpower\_dBm\_D(m)$$ + +During initialization and loop diagnostic mode, the received signal power in dBm, $RXpower\_dBm\_D(m)$ , shall be computed as the received subcarrier power, summed over those subcarriers of this band that are in the MEDLEYds set. During transmission of O-P-MEDLEY and R-P-MEDLEY, the transmit PSD for subcarriers in the MEDLEYds set is at the MREFPSDds level. Therefore, the received signal power shall be fine-tuned with the $g_i$ values for each subcarrier in the MEDLEYds set to estimate the signal power that will be received during showtime. + +Mathematically, this corresponds to: + +$$RXpower\_dBm\_D(m) = 10 \times \log_{10} \left( \sum_{i \in (MEDLEYds \cap DS(m))} \left( \text{Received\_subcarrier\_power\_mW}(i) \times g_i^2 \right) \right)$$ + +During showtime, the received signal power in dBm, $RXpower\_dBm\_D(m)$ , shall be computed as the received subcarrier power in showtime, summed over those subcarriers of this band that are in the MEDLEYds set. + +Mathematically, this corresponds to: + +$$RXpower\_dBm\_D(m) = 10 \times \log_{10} \left( \sum_{i \in (MEDLEYds \cap DS(m))} \left( \text{Received\_subcarrier\_power\_mW}(i) \right) \right)$$ + +In both equations, $MEDLEYds \cap DS(m)$ denotes all subcarriers of the MEDLEYds set that fall into the $m^{\text{th}}$ downstream band, $\text{Received\_subcarrier\_power\_mW}$ is the received power on subcarrier $i$ expressed in milli-Watts, and $g_i$ is the gain (linear scale) for subcarrier $i$ . + +The received power for $SATN\_U(m)$ shall be computed in the same way, but using subcarriers from the MEDLEYus set falling into the $m^{\text{th}}$ upstream band. + +For the SATN value determined during initialization, the received signal power for each subcarrier $i$ in the MEDLEYds set shall be fine-tuned with the $g_i$ value conveyed in the O-PMD (for the upstream direction) and R-PMD (for the downstream direction) messages to estimate the signal power that will be received during showtime. During loop diagnostic mode, the fine tuning shall be restricted to using $g_i$ values 0 (for subcarriers to which no bits can be allocated) and 1 (for subcarriers to which at least one bit can be allocated). For the SATN value determined during Showtime, the received signal subcarrier power shall be taken as measured. + +The transmitted signal power in dBm, $TXpower\_dBm\_D(m)$ , corresponds to the part of the NOMATP (see clause 10.3.4.2.1) falling in this band. It shall be computed as the aggregate transmit power, summed over the subcarriers of this band that are in the MEDLEYds set. During transmission of O-P-MEDLEY, the transmit PSD for subcarriers in the MEDLEYds set is at the MREFPSDds level. Therefore, the transmitted signal power shall be fine-tuned with the $g_i$ values for each subcarrier in the MEDLEYds set to estimate the signal power that will be transmitted during showtime. + +Mathematically, this corresponds to: + +$$TXpower\_dBm\_D(m) = 10 \times \log_{10} \Delta f + 10 \times \log_{10} \left( \sum_{i \in \text{MEDLEYds} \cap \text{DS}(m)} \left( 10^{\frac{\text{MREFPSD}[i]}{10}} \times g_i^2 \right) \right)$$ + +where $\text{MEDLEYds} \cap \text{DS}(m)$ denotes all subcarriers of the MEDLEYds set that fall into the $m^{\text{th}}$ downstream band, $\text{MREFPSD}[i]$ is the value of MREFPSDds for subcarrier $i$ in dBm/Hz as conveyed by the O-PRM message, $g_i$ is the gain (linear scale) for subcarrier $i$ , and $\Delta f$ is the subcarrier spacing in Hz. + +The transmit power for $SATN\_U(m)$ shall be computed in the same way, but using subcarriers from the MEDLEYus set falling into the $m^{\text{th}}$ upstream band, and the value of $\text{MREFPSD}[i]$ is the value of MREFPSDus for subcarrier $i$ in dBm/Hz as conveyed by the R-PRM message. + +For the SATN value determined during initialization, the transmit signal power for each subcarrier $i$ in the MEDLEYds set shall be fine-tuned with the $g_i$ value conveyed in the O-PMD (for the upstream direction) and R-PMD (for the downstream direction) messages to estimate the transmit signal power during showtime. During loop diagnostic mode, the fine tuning shall be restricted to using $g_i$ values 0 (for subcarriers to which no bits can be allocated) and 1 (for subcarriers to which at least one bit can be allocated). For the SATN value determined during showtime, the transmitted signal power shall be fine-tuned with the active $g_i$ values for each subcarrier in the MEDLEY set. + +The signal attenuation shall be measured by the receive PMD function during loop diagnostic mode and initialization (i.e., estimate the signal attenuation at the start of showtime). The measurement may be updated autonomously and shall be updated on request during showtime. The signal attenuation shall be sent to the far-end VME during initialization and loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the $SATN\_D(m)$ to the far-end VME on request during showtime. + +The signal attenuation per downstream band, $SATN\_D(m)$ , shall be represented as a 10-bit unsigned integer $satn$ , with the value of $SATN\_D(m)$ defined as $SATN\_D(m) = satn/10$ dB. This data format supports an $SATN\_D(m)$ granularity of 0.1 dB and an $SATN\_D(m)$ dynamic range of 102.2 dB (0 to 102.2 dB). + +An $SATN\_D(m)$ value indicated as $satn = 1023$ is a special value. It indicates that the signal attenuation is out of range to be represented. + +#### 11.4.1.1.6 Signal-to-noise ratio margin + +##### 11.4.1.1.6.1 General definition of signal-to-noise ratio margin + +The signal-to-noise ratio margin is the maximum increase (scalar gain, in dB) of the reference noise PSD (at all relevant frequencies), such that the BER of each bearer channel does not exceed $10^{-7}$ (see clause 9.8), without any change of PMD parameters (e.g., bits and gains) and PMS-TC parameters (e.g., $L_p$ , FEC parameters). The BER is referenced to the output of the PMS-TC function (i.e., the $\alpha/\beta$ interface). + +The definition of the reference noise PSD depends on the control parameter SNRM\_MODE. + +###### 11.4.1.1.6.1.1 SNRM\_MODE = 1 + +SNRM\_MODE = 1 is a mandatory capability for both VTUs. + +The reference noise PSD equals the received current-condition external noise PSD only, as measured by the near-end transceiver (i.e., equal to the PSD of the noise measured by the near-end transceiver at the constellation decoder or other relevant internal reference point when the only noise source is the external stationary noise applied to the U interface and no internal noise sources are present). + +NOTE – Mathematically this can be illustrated by: + +$$\text{Received\_External\_Noise\_PSD} = |H_{\text{RXfilter}}(f)|^2 \times \text{External\_Noise\_PSD\_at\_U\_interface}$$ + +###### 11.4.1.1.6.1.2 SNRM\_MODE = 2 + +SNRM\_MODE = 2 is an optional capability for both VTUs. + +The reference noise PSD equals the maximum of the received current-condition external noise PSD (as defined in SNRM\_MODE=1) and the received virtual noise PSD, at a common internal reference point. + +The received virtual noise PSD shall be determined by the transceiver as defined in the following equation. + +$$\text{Received\_Virtual\_Noise\_PSD} = |H(f)|^2 \times \text{TXREFVN}$$ + +where TXREFVN is the transmitter-referred virtual noise PSD MIB parameter. + +$|H(f)|^2$ is calculated as: + +$$|H(f)|^2 = \frac{\text{Actual\_Received\_Signal\_PSD}}{\text{Actual\_Transmit\_Signal\_PSD}}$$ + +where: + +- Actual\_Transmit\_Signal\_PSD is the actual transmit signal PSD at the far-end transmitter as calculated by the near-end transceiver. +- Actual\_Received\_Signal\_PSD is the actual received signal PSD at the near-end transceiver as measured by the near-end transceiver (i.e., equal to the PSD measured by the near-end transceiver at the constellation decoder or other relevant internal reference point) during initialization and Showtime. + +Mathematically this can be expressed as: + +$$\text{Actual\_Received\_Signal\_PSD} = |H_{\text{RXfilter}}(f)|^2 \times \text{Received\_Signal\_PSD\_at\_U\_interface}$$ + +NOTE – A measurement of the current-condition external noise PSD could be overly optimistic, as it only represents a snapshot in time, not taking into account the future increase in noise PSD (e.g., due to additional VDSL2 lines being switched on). The SNRM\_MODE=2 is defined to prevent the VTU's bit loading algorithm from assigning an overly optimistic number of bits to a subcarrier. This is achieved by defining (via the transmitter-referred virtual noise PSD parameter TXREFVN) an anticipated noise PSD, which may be a function of frequency that can be used for bit loading. + +This method can be used to avoid or reduce periods with excessive BER and retrains, in order to assure service quality and stability. It is expected that the configuration, via the MIB, is based on anticipated service penetration and noise environment. + +#### 11.4.1.1.6.1.3 SNRM\_MODE = 3 + +SNRM\_MODE = 3 is an optional capability for upstream (i.e., VTU-O receiver) only. + +The reference noise PSD equals the maximum of the received current-condition external noise PSD (as defined in SNRM\_MODE=1) and the received virtual noise PSD, at a common internal reference point. + +The received virtual noise PSD shall be determined by the transceiver as defined in the following equation. + +$$\text{Received\_Virtual\_Noise\_PSD} = |H_{\text{RXfilter}}(f)|^2 \times \text{RXREFVN}$$ + +where: + +$|H_{\text{RXfilter}}(f)|$ is the magnitude of the transfer function between the U-interface and the common internal reference point, and + +RXREFVN is the receiver-referred virtual noise PSD MIB parameter. + +NOTE – A measurement of the current-condition external noise PSD could be overly optimistic, as it only represents a snapshot in time, not taking into account the future increase in noise PSD (e.g., due to additional VDSL2 lines being switched on). The SNRM\_MODE = 3 is defined to prevent the VTU's bit loading algorithm from assigning an overly optimistic number of bits to a subcarrier. This is achieved by defining (via the receiver-referred virtual noise PSD parameter RXREFVN) an anticipated noise PSD, which may be a function of frequency that can be used for bit loading. + +This method can be used to avoid or reduce periods with excessive BER and retrains, in order to assure service quality and stability. It is expected that the configuration, via the MIB, is based on anticipated service penetration and noise environment. + +#### 11.4.1.1.6.1.4 SNRM\_MODE = 4 + +SNRM\_MODE = 4 is an optional capability for both upstream and downstream. + +The reference noise PSD equals the maximum of the received current-condition external noise PSD (as defined in SNRM\_MODE=1) and the received virtual noise PSD, at a common internal reference point. + +In the downstream direction, the received virtual noise PSD shall be determined by the transceiver as defined in the following equation: + +$$\text{Received\_Virtual\_Noise\_PSD} = |H(f)|^2 \times \text{TXREFVNdS}$$ + +where: + +$|H(f)|^2$ is calculated as in SNRM\_MODE=2, and + +TXREFVNdS is the transmitter-referred virtual noise PSD control parameter as conveyed in O-SIGNATURE. + +In SNRM\_MODE= 4, the control parameter TXREFVNdS is a combination of the configuration parameter TXREFVNdS and the configuration parameter TXREFVNSFds as described in clause 11.4.2.5. + +In the upstream direction, the received virtual noise PSD shall be determined by the transceiver as defined in the following equation: + +$$\text{Received\_Virtual\_Noise\_PSD} = |H_{\text{RXfilter}}(f)|^2 \times \text{RXREFVNUs}$$ + +where: + +$|H_{RXfilter}(f)|$ is the magnitude of the transfer function between the U-interface and the common internal reference point, and + +RXREFVNus is the receiver-referred virtual noise PSD control parameter. + +In SNRM\_MODE=4, the control parameter RXREFVNus is a combination of the configuration parameter RXREFVNus and the configuration parameter RXREFVNSFus as described in clause 11.4.2.4. + +NOTE 1 – A measurement of the current-condition external noise PSD could be overly optimistic, as it only represents a snapshot in time, not taking into account the future increase in noise PSD (e.g., due to additional VDSL2 lines being switched on). SNRM\_MODE = 4 is defined to prevent the VTU's bit loading algorithm from assigning an overly optimistic number of bits to a subcarrier. This is achieved by defining (via the virtual noise PSD parameter and the virtual noise scaling factor parameter) an anticipated noise PSD, which may be a function of frequency that can be used for bit loading. This method can be used to avoid or reduce periods with excessive BER and retrains, in order to assure service quality and stability. It is expected that the configuration, via the MIB, is based on anticipated service penetration and noise environment. + +NOTE 2 – SNRM\_MODE=4 is similar to SNRM\_MODE=3 in the upstream direction and SNRM\_MODE=2 in the downstream direction. Per line configuration in SNRM\_MODE=2, 3 and 4 may be accomplished by configuration of a different value for the configuration parameter Virtual Noise (VNus or VNdS, see clauses 7.3.1.7.3 and 7.3.1.7.4 of [ITU-T G.997.1]) on a line by line basis. Per line configuration in SNRM\_MODE=4 may also be accomplished by the configuration of a common value for the configuration parameter Virtual Noise (VNus or VNdS) for a group of lines combined with the configuration of a scaling factor (TXREFVNSFds or RXREFVNSFus) on a line by line basis. + +#### 11.4.1.1.6.1.5 SNRM\_MODE = 5 + +SNRM\_MODE = 5 is an optional capability for both upstream and downstream. A transceiver supporting operation with SNRM\_MODE = 5 shall also support SRA. + +The SNRM\_MODE = 5 can be applied in both directions (i.e., for both VTU-O and VTU-R receivers). If SNRM\_MODE = 5 is applied in at least one direction, then an *msg* bit rate of at least 64 kbit/s shall be used in both directions. + +The reference noise PSD is equal to the maximum of the received current-condition external noise PSD (as defined in SNRM\_MODE=1) and the received showtime adaptive virtual noise (SAVN) PSD, at a common internal reference point. + +The received SAVN PSD value shall be determined by the transceiver as defined in the following equation. + +$$\text{Received\_SAVN\_PSD} = |H(f)|^2 \times \text{TXREFSAVN}(f)$$ + +where TXREFSAVN(*f*) is the transmitter-referred SAVN PSD parameter at frequency *f*, and $|H(f)|^2$ is calculated as defined in clause 11.4.1.1.6.1.2. + +The value of TXREFSAVN is set at initialization and may be updated during showtime. At initialization, the downstream SAVN PSD and upstream SAVN PSD are determined by the VTU-O. The initial value of the downstream SAVN PSD (TXREFSAVNdS) is communicated to the VTU-R in the TXREFVNdS field in the O-SIGNATURE message (see clause 12.3.3.2.1.1). During showtime, the VTU-O may update the value of the downstream SAVN PSD based on noise estimations or actual noise measurements at the VTU-R, e.g., noise changes due to other lines going in and out of the low power mode (see Annex E of [ITU-T G.998.4]). The update of TXREFSAVNdS is communicated to the VTU-R via a SAVN-Update eoc command (see clause 11.2.3.16). During showtime, the VTU-O may also update the value of the upstream SAVN PSD based on noise estimations or actual noise measurements at the near-end. The VTU-O may estimate the SNR at the remote end by using the Test Parameter Read command defined in clause 11.2.3.11. Other estimation methods are for further study. Upon an update of the received SAVN PSD, the VTU shall verify whether the update requires + +a modification of the bit loading. If a modification is required, the VTU shall perform an SRA to adjust the bit loading in accordance with the updated value of the received SAVN PSD. + +NOTE 1 – To identify changes in the SNR, the VTU-O ME may request the SNR read right after implementation of an SRA command, or a bit swap command, or after SOS. + +The range of TXREFSAVNds, TXREFSAVNus values shall be in the boundaries determined by the CO-MIB (parameters TXREFSAVNds-MIN/MAX, TXREFSAVNus-MIN/MAX defined in Table 11-42.1). + +NOTE 2 – To set the initial values of TXREFSAVNds, TXREFSAVNus, the VTU-O may take in account the values TXREFVNds and TXREFVNus (see clause 11.4.2.1) provided by the CO-MIB, respectively. + +**Table 11-42.1 – CO-MIB configuration parameters related to SAVN** + +| Configuration parameter | Definition | +|-------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TXREFSAVNds-MIN | TXREFSAVNds-MIN indicates a minimum value, such that TXREFSAVNds is greater than or equal to TXREFSAVNds-MIN for all applicable subcarriers. The valid range is –150 to –23 dBm/Hz in steps of 0.5dB. | +| TXREFSAVNds-MAX | TXREFSAVNds-MAX indicates a maximum value, such that TXREFSAVNds is less than or equal to TXREFSAVNds-MAX for all applicable subcarriers. The valid range is –150 to –23 dBm/Hz in steps of 0.5dB. | +| TXREFSAVNus-MIN | TXREFSAVNus-MIN indicates a minimum value, such that TXREFSAVNus is greater than or equal to TXREFSAVNus-MIN for all applicable subcarriers. The valid range is –150 to –23 dBm/Hz in steps of 0.5dB. | +| TXREFSAVNus-MAX | TXREFSAVNus-MAX indicates a maximum value, such that TXREFSAVNus is less than or equal to TXREFSAVNus-MAX for all applicable subcarriers. The valid range is –150 to –23 dBm/Hz in steps of 0.5dB. | + +#### 11.4.1.1.6.2 Signal-to-noise ratio margin parameter (SNRM) + +The signal-to-noise ratio margin parameter, SNRM, is the signal-to-noise ratio margin (as defined in clause 11.4.1.1.6.1) measured over all subcarriers, except the subcarriers assigned to the ROC, in a transmission direction for which $b_i > 0$ . The received virtual noise PSD as defined in clauses 11.4.1.1.6.1.2, 11.4.1.1.6.1.3, 11.4.1.1.6.1.4, and 11.4.1.1.6.1.5 shall be taken into account, respectively, when configured in SNRM\_MODE=2, SNRM\_MODE=3, SNRM\_MODE=4, and SNRM\_MODE=5. + +The signal-to-noise ratio margin shall be measured by the receive PMD function during initialization. The measurement may be updated autonomously and shall be updated on request during showtime. The SNRM shall be sent to the far-end VTU during initialization and loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the SNRM to the far-end VME on request during showtime. + +To determine the SNRM, the receive PMD function must be able to first determine the bits and gains table. During loop diagnostic mode, the receive PMD function shall use the special value to indicate that the SNRM value was not measured. + +The signal-to-noise ratio margin in the downstream direction shall be represented as a 10-bit twos complement signed integer *snrm*, with the value of SNRMds defined as $SNRMds = snrm/10$ dB. This data format supports an SNRMds granularity of 0.1 dB and an SNRMds dynamic range of 102.2 dB (–51.1 to +51.1 dB). + +An SNRMds value indicated as $snrm = -512$ is a special value. It indicates that the signal-to-noise ratio margin is out of the range to be represented. During loop diagnostic mode, the special value shall be used to indicate that the SNRMds value was not measured. + +The same definition and representation shall apply to the signal-to-noise ratio margin in the upstream direction, SNRMus. + +#### 11.4.1.1.6.3 Signal-to-noise ratio margin per band (SNRM-pb) + +The signal-to-noise ratio margin in the $m^{\text{th}}$ downstream band is denoted as SNRM\_D( $m$ ), and the signal-to-noise ratio margin in the $m^{\text{th}}$ upstream band is denoted as SNRM\_U( $m$ ). For ease of notation, this clause provides requirements and definitions in terms of the downstream signal-to-noise ratio margin, but the same definitions and requirements also apply to SNRM\_U( $m$ ). + +The signal-to-noise ratio margin per band parameter SNRM-pb is the signal-to-noise ratio margin (as defined in clause 11.4.1.1.6.1) measured over all subcarriers in a particular band for which $b_i > 0$ . The received virtual noise PSD as defined in clauses 11.4.1.1.6.1.2, 11.4.1.1.6.1.3, 11.4.1.1.6.1.4, and 11.4.1.1.6.1.5 shall be taken into account, respectively, when configured in SNRM\_MODE=2, SNRM\_MODE=3, SNRM\_MODE=4, and SNRM\_MODE=5. + +The signal-to-noise ratio margin per band is the maximum increase (in dB) in the received noise power that can be tolerated in this band, such that the VTU can still meet all target BERs over all bearer channels. + +The signal-to-noise ratio margin per band shall be measured by the receive PMD function during initialization. The measurement may be updated autonomously and shall be updated on request during showtime. The signal-to-noise ratio margin per band shall be sent to the far-end VME during initialization and loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the SNRM-pb to the far-end VME on request during showtime. + +To determine the SNRM-pb, the receive PMD function must be able to first determine the bits and gains table. During loop diagnostic mode, the receive PMD function shall use the special value to indicate that the SNRM-pb value was not measured. + +The signal-to-noise ratio margin per downstream band shall be represented as a 10-bit twos complement signed integer $snrm$ , with the value of SNRM\_D( $m$ ) defined as $\text{SNRM\_D}(m) = snrm/10$ dB. This data format supports an SNRM\_D( $m$ ) granularity of 0.1 dB and an SNRM\_D( $m$ ) dynamic range of 102.2 dB (-51.1 to +51.1 dB). + +An SNRM\_D( $m$ ) value indicated as $snrm = -512$ is a special value. It indicates that the signal-to-noise ratio margin is out of the range to be represented. During loop diagnostic mode, the special value shall be used to indicate that the SNRM\_D( $m$ ) value was not measured. + +#### 11.4.1.1.6.4 Signal-to-noise ratio margin for the ROC (SNRM-ROC) + +The SNRM-ROC is the signal-to-noise ratio margin related to transmission of the ROC, as defined in clause 9.1, Figure 9-2. The definition of SNRM-ROC is as in clause 11.4.1.1.6.1 applied to the MPS-TC and BER= $10^{-7}$ for all bits transmitted over latency path #0, Figure 9-2. The SNRM-ROC shall be measured over all subcarriers assigned to the ROC for which $b_i > 0$ in a transmission direction. The received virtual noise PSD as defined in clause 11.4.1.1.6.1.2 shall be taken into account when configured in SNRM\_MODE=2. + +The SNRM-ROC shall be measured by the receive PMD function during initialization. The measurement may be updated autonomously and shall be updated on request during Showtime. The SNRM-ROC shall be sent to the far-end VTU during initialization and shall be sent on request to the near-end VME at any time. The near-end VME shall send the SNRM-ROC to the far-end VME on request during Showtime. The receive PMD function shall use a special value to indicate that the SNRM value was not measured (e.g., in Loop Diagnostic mode or if the ROC is not enabled or not supported). + +The SNRM-ROC shall use the same representation as defined for SNRM in clause 11.4.1.1.6.2. + +#### 11.4.1.1.7 Attainable net data rate (ATTNDR) + +The attainable net data rate (ATTNDR) is the maximum net data rate that the receive PMS-TC and PMD functions are designed to support, assuming certain conditions. Assumed conditions depend on the control parameter *attndr\_method* (single method applicable to both upstream and downstream directions): either the basic method (*attndr\_method*=0, see clause 11.4.1.1.7.1) or the improved methods (*attndr\_method*=1 or 2, see clause 11.4.1.1.7.2). The *attndr\_method* value is sent to the VTU-R during initialization (see clause 12.3.5.2.2.1). The actual *attndr\_method* value is reported through the CO-MIB parameter ATTNDR\_ACTMETHOD (see clause 7.5.1.41.1 of [ITU-T G.997.1]). + +The improved Attainable net data rate method shall be used if the CO-MIB parameter ATTNDR\_METHOD (see clause 7.3.1.15.1 of [ITU-T G.997.1]) is set to a value of 1 or 2, and the mode is supported by the VTU-O and by the VTU-R. In this case the value of the control parameter *attndr\_method* shall have the same value as the CO-MIB configuration parameter ATTNDR\_METHOD (i.e., *attndr\_method*=ATTNDR\_METHOD). Otherwise, the basic attainable net data rate method shall be used. In this case the value of the control parameter *attndr\_method* is zero (i.e., *attndr\_method*=0). + +To accurately determine the attainable net data rate (ATTNDR), the receive PMD function must be able to first determine the bits and gains table. Therefore, during loop diagnostic mode, the ATTNDR value for upstream and downstream shall be calculated as: + +$$\text{ATTNDR} = \sum_{i=0}^{MSI} \min \left\{ \text{round} \left[ \log_2 \left( 1 + 10^{(\text{SNR}(i \times \Delta f) - \text{SNRGAP} - \text{TARSNRM})/10} \right) \right], 15 \right\} \times 4 \text{ kbit/s}$$ + +with $\text{SNR}(i \times \Delta f)$ in dB as defined in clause 11.4.1.1.3, but accounting for the received virtual noise PSD when configured in SNRM\_MODE=2, SNRM\_MODE=3, SNRM\_MODE=4, or SNRM\_MODE=5 and SNRGAP= 9.75 dB (Note 1). + +NOTE 1 – The SNRGAP value is defined for a $10^{-7}$ bit error ratio on 4-QAM (no coding gain, $\text{INP\_min}_0 = 0$ ). + +NOTE 2 – The value calculated for ATTNDR during loop diagnostic mode may not be identical to the value calculated during Showtime with the same PMD parameters and under the same loop conditions. + +The attainable net data rate shall be calculated by the receive PMS-TC and PMD functions during loop diagnostic mode and initialization. The measurement may be updated autonomously and shall be updated on request during showtime. The attainable net data rate shall be sent to the far-end VME during loop diagnostic mode and shall be sent on request to the near-end VME at any time. The near-end VME shall send the ATTNDR to the far-end VME on request during showtime. + +The attainable net data rate shall be represented as a 32-bit unsigned integer *attndr*, with the value of ATTNDR defined as $\text{ATTNDR} = \text{attndr}$ bit/second. This data format supports an ATTNDR granularity of 1 bit/s. + +No special value is defined. + +##### 11.4.1.1.7.1 The basic attainable net data rate method + +Support of the basic attainable net data rate method is mandatory. + +The attainable net data rate is the maximum net data rate that the receive PMS-TC and PMD functions are designed to support, assuming the following conditions: + +- single bearer channel and single latency operation; +- target SNR margin equal to the configured TARSNRMds/TARSNRMus downstream and upstream, respectively; + +- latency not to exceed the highest latency configured for the bearer channel ( $delay\_act_0 \leq delay\_max_0$ ); +- accounting for all coding gains available (e.g., trellis coding, FEC) within the latency bound; +- accounting for the channel characteristics at the instant of measurement; and +- accounting for the received virtual noise PSD when configured in SNRM\_MODE=2, SNRM\_MODE=3, SNRM\_MODE=4, or SNRM\_MODE=5. + +NOTE – The conditions of the basic method in this version of the Recommendation are unchanged compared to the conditions for ATTNDR calculation in previous versions of this Recommendation. This set of conditions did not specify a number of conditions to calculate ATTNDR, which lead to vendor discretionary behaviour in the reported ATTNDR values. It is recommended that implementations that are upgraded from a previous version of this Recommendation to this version of this Recommendation, in case of *atndr\_method*=0 use the same vendor discretionary behaviour as used when operating according to the previous version of this Recommendation. + +#### 11.4.1.1.7.2 The improved attainable net data rate method + +Support of the improved attainable net data rate method is optional. + +The attainable net data rate is the maximum net data rate that the receive PMS-TC and PMD functions are designed to support, assuming the conditions of the basic attainable net data rate method (see clause 11.4.1.1.7.1) and the following conditions: + +- if operating in single bearer channel mode, the ATTNDR calculation shall use single bearer channel mode. If operating in dual bearer channel mode, the ATTNDR calculation shall use single bearer channel mode (see clause 8.1.3.1); +- if operating in single latency mode, the ATTNDR calculation shall use single latency mode. If operating in dual latency mode, the ATTNDR calculation shall use single latency mode. If operating in single latency with ROC mode, the ATTNDR calculation shall use single latency with ROC mode (see clause 9.1); +- if the control parameter *atndr\_method* is set to a value of 1, the VTU-O and VTU-R shall use the impulse noise protection limit *INP\_min0* with value as indicated in O-TPS (see clause 12.3.5.2.1.2). If O-TPS configures for dual bearer channel mode, then the highest *INP\_minn* over the bearer channels shall be used; +- if the control parameter *atndr\_method* is set to a value of 2, the VTU-O and VTU-R shall use an impulse noise protection limit *INP\_min0* = 0; +- the VTU-O and VTU-R shall use the maximum delay *delay\_max0* with value as indicated in O-TPS (see clause 12.3.5.2.1.2). If O-TPS configures for dual bearer channel mode, then the lowest *delay\_maxn* over the bearer channels shall be used; +- use of Erasure decoding or not is identical to usage on the bearer channels; +- taking into account the framing limitations; +- if ATM bonding is set in the ITU-T G.994.1 bonding code tree, the VTU-O and VTU-R shall use the minimum delay *delay\_min0* as defined in clause L.2.7. If O-TPS configures for dual bearer channel mode, then the lowest *delay\_minn* over the bearer channels shall be used; +- Taking into account the value of the ATTNDR\_MDOSPLITparameter; +- Net data rate is not limited by the configured maximum net data rate; +- Channel initialization policy CIP = 0; +- Transmit PSD is equal to MREFPSD for all subcarriers for which $g_i \neq 0$ . + +NOTE 1 – The ATTNDR value may be lower due to possible transmit power reductions, as a consequence of configured MAXMARGIN setting, configured MAXNDR setting and vendor discretionary transmit power reductions (e.g., subcarriers with $g_i = 0$ , due to AFE dynamic range, ...). + +NOTE 2 – The basic method does not specify a number of conditions to calculate ATTNDR, which leads to vendor discretionary behaviour in the reported ATTNDR values. The improved method defines additional conditions to reduce variation of reported ATTNDR values over implementations. + +When the ATTNDR value is reported during Showtime, the following parameters used in the calculation of the ATTNDR shall also be reported over the eoc with the ATTNDR value (see Table 11-30), and also be reported in the CO-MIB with the ATTNDR value (see clauses 7.5.1.19 and 7.5.1.20 of [ITU-T G.997.1]): + +- *ATTNDR\_INP\_act0* (see clauses 7.5.1.41.2 and 7.5.41.3 of [ITU-T G.997.1]); +- *ATTNDR\_delay\_act0* (see clauses 7.5.1.41.6 and 7.5.41.7 of [ITU-T G.997.1]). + +The parameter *ATTNDR\_INP\_act0* is the far-end actual impulse noise protection used in the calculation of the ATTNDR. The actual impulse noise protection *ATTNDR\_INP\_act0* shall be represented as an 8-bit unsigned integer *attnr\_inp\_act0*, with the value of *ATTNDR\_INP\_act0* defined as *ATTNDR\_INP\_act0* = *attnr\_inp\_act0* / 10 DMT symbols. This data format supports an *ATTNDR\_INP\_act0* granularity of 0.1 DMT symbol. The range is from 0 DMT symbols (represented as 0) to 25.4 DMT symbols (represented as 254). The value 255 is a special value indicating an *ATTNDR\_INP\_act0* higher than 25.4 DMT symbols. + +The parameter *ATTNDR\_delay\_act0* is the far-end actual delay used in the calculation of the ATTNDR. The actual delay *ATTNDR\_delay\_act0* shall be represented as an 8-bit unsigned integer *attnr\_delay\_act0*, with the value of *ATTNDR\_delay\_act0* defined as *ATTNDR\_delay\_act0* = *attnr\_delay\_act0* / 10 ms. This data format supports an *ATTNDR\_delay\_act0* granularity of 0.1 ms. The range is from 0 ms (represented as 0) to 25.4 ms (represented as 254). The value 255 is a special value indicating an *ATTNDR\_DELAY\_act0* higher than 25.4 ms. + +#### 11.4.1.1.8 Actual aggregate transmit power (ACTATP) + +The actual aggregate transmit power (ACTATP) is the total amount of output power delivered by the transmit PMD function to the U reference point at tip-and-ring (in dB), at the instant of measurement. The transmit PMD function shall take the NOMATP (see clause 10.3.4.2.1) as a best estimate of the near-end actual aggregate transmit power. + +The receive PMD function shall take NOMATP (see clause 10.3.4.2.1) as a best estimate of the far-end actual aggregate transmit power. + +The near-end and far-end actual aggregate transmit power shall be calculated by the VTU during initialization using the assigned values of $g_i$ . The measurement may be updated autonomously and shall be updated on request during showtime. The near-end and far-end actual aggregate transmit power shall be sent on request to the near-end VME. The near-end VME shall send the near-end and far-end ACTATP to the far-end VME on request during showtime. + +To determine the near-end ACTATP, the transmit PMD function must first receive the bits and gains table from the receive PMD function. Therefore, during loop diagnostic mode, the $g_i$ values shall be determined as value 1 (for all subcarriers in the MEDLEY set). + +The actual aggregate transmit power shall be represented as a 10-bit twos complement signed integer *actatp*, with the value of ACTATP defined as *ACTATP* = *actatp*/10 dBm. This data format supports an ACTATP granularity of 0.1 dB, with an ACTATP dynamic range of 62 dB (–31 to + 31 dBm). + +An ACTATP value indicated as *actatp* = –512 is a special value. It indicates that the actual aggregate transmit power is out of the range to be represented. + +#### 11.4.1.1.9 Actual impulse noise protection (INP\_act) + +The actual impulse noise protection *INP\_actn* of bearer channel #*n* is defined in clause 9.6. + +The actual impulse noise protection *INP\_actn* of bearer channel #*n* shall be represented as an 8-bit unsigned integer *inp\_actn*, with the value of *INP\_actn* defined as *INP\_actn* = *inp\_actn* / 10 DMT + +symbols. This data format supports an $INP\_act_n$ granularity of 0.1 DMT symbol. The range is from 0 DMT symbols (represented as 0) to 25.4 DMT symbols (represented as 254). The value 255 is a special value indicating an $INP\_act_n$ higher than 25.4 DMT symbols. + +#### 11.4.1.1.10 Actual impulse noise protection of the ROC ( $INP\_act-ROC$ ) + +The $INP\_act-ROC$ is the actual impulse noise protection of the ROC, as defined in clause 9.1, Figure 9-2. It shall be computed as $INP\_act-ROC = INP\_no\_erasure_0$ (see clause 9.6). + +The parameter $INP\_act-ROC$ is expressed in DMT symbols. + +The parameter $ACTINP-ROC$ in the CO-MIB is expressed in multiples of $T_{4k}$ . The value is coded in fractions of $T_{4k}$ periods with a granularity of 0.1 of a period. The range is from 0 to 25.4. At the Q-reference point, a special value indicates an $ACTINP-ROC$ higher than 25.4. The $T_{4k}$ is defined in clause 10.4.4. + +The VTU-O shall calculate $ACTINP-ROC$ as follows: + +- For 4.3125 kHz subcarrier spacing: + +$$ACTINP-ROC = \text{MIN}(\lfloor 10 \times INP\_act-ROC \rfloor / 10; 25.5)$$ +- For 8.625 kHz subcarrier spacing: + +$$ACTINP-ROC = \text{MIN}(\lfloor 5 \times INP\_act-ROC \rfloor / 10; 25.5)$$ + +#### 11.4.1.2 Accuracy of test parameters + +This clause defines accuracy requirements for test parameters defined in clause 11.4.1.1. The accuracy requirement is expressed as a tolerance relative to a reference value. Both the reference value and the allowed tolerance are defined in this clause. + +The accuracy requirements of test parameters are optional. A VTU may comply with the accuracy requirements for all or a subset of the test parameters. For subcarriers and subcarrier groups to which accuracy requirements do not apply (see clauses 11.4.1.2.1 to 11.4.1.2.8), the VTU shall report test parameters as defined in clause 11.4.1.1 but the accuracy of these reported values may not comply with the accuracy requirements further defined in this clause. + +NOTE – The measurement of test parameter reference values involves the use of test equipment. The accuracy requirements defined in this clause do not take into account test equipment tolerance. Test equipment tolerance is out of the scope of this Recommendation and is to be added to the tolerances defined in this clause. + +##### 11.4.1.2.1 Accuracy of channel characteristics function per subcarrier group (CCF-ps) + +###### 11.4.1.2.1.1 Accuracy of $H_{log}(k \times G \times \Delta f)$ + +The downstream $H_{LOG}(f)$ reference value for frequency $k \times G \times \Delta f$ shall be defined as: + +$$H_{LOG\_reference\_ds}(k \times G \times \Delta f) = MREFPSD_{ds}(k \times G \times \Delta f) - PSD\_UR2(k \times G \times \Delta f),$$ + +where $PSD\_UR2(k \times G \times \Delta f)$ is the PSD measured at the U-R2 reference point with the VTU-O connected to the loop and frozen in the O-P-MEDLEY stage of initialization with the SOC in the O-IDLE state, and with the VTU-R replaced by an $R_N=100$ Ohm resistance terminating the loop. + +The upstream $H_{LOG}(f)$ reference value for frequency $k \times G \times \Delta f$ shall be defined as: + +$$H_{LOG\_reference\_us}(k \times G \times \Delta f) = MREFPSD_{us}(k \times G \times \Delta f) - PSD\_UO2(k \times G \times \Delta f),$$ + +where $PSD\_UO2(k \times G \times \Delta f)$ is the PSD measured at the U-O2 reference point with the VTU-R connected to the loop and frozen in the R-P-MEDLEY stage of initialization with the SOC in the R-IDLE state, and with the VTU-O replaced by an $R_N=100$ Ohm resistance terminating the loop. + +NOTE 1 – The feature to freeze a VTU in the MEDLEY stage of initialization exists solely to allow a test bed to be constructed for the purpose of measuring the $H_{log}(f)$ reference values. It applies only to specific + +transceivers serving as the 'transmit transceiver' of the test environment and is not a requirement for compliance with this Recommendation. + +The receiving VTU shall measure the $H\log(f)$ values under the same loop, noise, temperature, and configuration settings that are used for measuring the $H\log(f)$ reference values. + +The accuracy requirements for the $H\log(k \times G \times \Delta f)$ shall only apply to those subcarrier groups with an SNR (as defined in clause 11.4.1.1.3) $\geq 12$ dB, where the SNR is the SNR value measured during initialization, after the channel discovery phase. + +The accuracy requirements for the downstream $H\log(k \times G \times \Delta f)$ (ITU-T G.997.1 parameter HLOGpsds): + +- shall not apply to subcarrier groups that contain subcarriers from the downstream BLACKOUT set; +- shall not apply to subcarrier groups that contain subcarriers in the RFI bands or that contain any of the 15 subcarriers adjacent to each side of the RFI bands, and +- shall only apply to subcarrier groups for which all subcarriers within the group fall within the following frequency ranges (defined as a part of the passband): + - For Annex A, Masks D-32, D-48, and D-64 of Table A.8: + - Subcarrier 92 to Subcarrier 869 and Subcarrier 1206 to Subcarrier 1971 for profiles 8a, 8b, 8c, 8d, 12a, 12b and 17a. + - For Annex A Mask D-128 of Table A.8: + - Subcarrier 184 to Subcarrier 869 and Subcarrier 1206 to Subcarrier 1971 for profiles 8a, 8b, 8c, 8d, 12a, 12b and 17a. + - For Annex B band plan 998 of Table B.1: + - Subcarrier 92 to Subcarrier 869 and Subcarrier 1206 to Subcarrier 1971 for profiles 8a, 8b, 8c, 8d, 12a, 12b and 17a. + - For Annex B band plan 997 of Table B.1: + - Subcarrier 92 to Subcarrier 695 and Subcarrier 1183 to Subcarrier 1634 for profiles 8a, 8b, 8c, 8d, 12a, 12b and 17a. + - For Annex C, Masks in Tables C.1, C.2, C.5 and C.6: + - Subcarrier 92 to Subcarrier 869 and Subcarrier 1206 to Subcarrier 1971 for profiles 8a, 8b, 8c, 8d, 12a, 12b and 17a. + - For Annex C, Masks in Table C.9: + - Subcarrier 214 to Subcarrier 869 and Subcarrier 1206 to Subcarrier 1971 for profiles 8a, 8b, 8c, 8d, 12a, 12b and 17a. + +Accuracy requirements for Annex B band plans 998ADE are for further study. + +Accuracy requirements for Profile 30a are for further study. + +Accuracy requirements for Annex N band plans are for further study. + +Accuracy requirements outside these specified ranges are for further study. + +The accuracy requirements for the upstream $H\log(k \times G \times \Delta f)$ (ITU-T G.997.1 parameter HLOGpsus): + +- shall not apply to subcarrier groups that contain subcarriers from the upstream BLACKOUT set; +- shall not apply to subcarrier groups that contain subcarriers in the RFI bands or that contain any of the 15 subcarriers adjacent to each side of the RFI bands; and + +- shall only apply to subcarrier groups for which all subcarriers within the group fall within the following frequency ranges (defined as a part of the passband): + - For Annex A, Annex B Band Plan 998 of Table B.1 and Annex C: + - Subcarrier 870 to Subcarrier 1205 for profiles 8a, 8b, 8c and 8d. + - Subcarrier 870 to Subcarrier 1205 and Subcarrier 1972 to Subcarrier 2782 for profiles 12a, 12b and 17a. + - For Annex B Band Plan 997 of Table B.1: + - Subcarrier 696 to Subcarrier 1182 for profile 8c. + - Subcarrier 696 to Subcarrier 1182 and Subcarrier 1635 to Subcarrier 2047 for profiles 8a, 8b and 8d. + - Subcarrier 696 to Subcarrier 1182 and Subcarrier 1635 to Subcarrier 2782 for profiles 12a, 12b and 17a. + +Accuracy requirements for Annex B band plans 998ADE are for further study. + +Accuracy requirements for Profile 30a are for further study. + +Accuracy requirements for Annex N band plans are for further study. + +Accuracy requirements for the US0 band (for all relevant profiles) are for further study. + +Accuracy requirements outside these frequency ranges are for further study. + +NOTE 2 – Having such specified ranges for accuracy requirements avoids variations due to the tolerances and effects of the filtering at the low ends of the passband and of the effects of folding at the high end of the passband. + +The accuracy requirements for downstream and upstream $H\log(k \times G \times \Delta f)$ shall only apply for those subcarrier groups where the loop impedance ( $Z_{loop}$ ) falls within the following ranges for all the subcarriers in the group: + +- Impedance magnitude is between 100 Ohm and 120 Ohm; +- Impedance imaginary component is between –20 Ohm and 0 Ohm. + +$Z_{loop}$ is defined as the impedance seen by the receiving transceiver under test, looking into the loop, including the transmitting transceiver connected to the loop at the far end. + +Accuracy requirements for downstream and upstream $H\log(k \times G \times \Delta f)$ , for frequencies where $Z_{loop}$ falls outside this range, are for further study. + +NOTE 3 – Appendix II provides an informative discussion of the effects on the accuracy of $H\log(f)$ measurements caused by impedance mismatch between a nominal 100 Ohm termination of the loop and possible termination impedances ( $Z_{VTU}$ ) actually provided by a VTU. + +For each subcarrier group where the accuracy requirement for downstream $H\log(k \times G \times \Delta f)$ applies (based on its subcarrier indexes and downstream $SNR(k \times G \times \Delta f)$ value only, and not considering restrictions related to its $Z_{loop}$ values), and where $HLOGps\_reference\_ds(k \times G \times \Delta f)$ is above –90 dB, a downstream $H\log(k \times G \times \Delta f)$ value different from the special value defined in clause 11.4.1.1.1 shall be reported. + +For each subcarrier group where the accuracy requirement for downstream $H\log(k \times G \times \Delta f)$ applies, and where $HLOGps\_reference\_ds(k \times G \times \Delta f)$ is above –90 dB, the absolute error between the downstream $H\log(k \times G \times \Delta f)$ and $HLOGps\_reference\_ds(k \times G \times \Delta f)$ shall be $\leq 3$ dB. + +The accuracy requirements for downstream $H\log(k \times G \times \Delta f)$ shall apply to its measurement either during Initialization or in Loop Diagnostic mode. + +For each subcarrier group where the accuracy requirement for upstream $H\log(k \times G \times \Delta f)$ applies (based on its subcarrier indexes and upstream $SNR(k \times G \times \Delta f)$ value only, and not considering + +restrictions related to its $Z_{loop}$ values), and where HLOGps\_reference\_us( $k \times G \times \Delta f$ ) is above $-90$ dB, an upstream Hlog( $k \times G \times \Delta f$ ) value different from the special value defined in clause 11.4.1.1.1 shall be reported. + +For each subcarrier group where the accuracy requirement for upstream Hlog( $k \times G \times \Delta f$ ) applies, and where HLOGps\_reference\_us( $k \times G \times \Delta f$ ) is above $-90$ dB, the absolute error between the upstream Hlog( $k \times G \times \Delta f$ ) and the HLOGps\_reference\_us( $k \times G \times \Delta f$ ) shall be $\leq 3$ dB. + +The accuracy requirements for upstream Hlog( $k \times G \times \Delta f$ ) shall apply to its measurement either during Initialization or in Loop Diagnostic mode. + +#### 11.4.1.2.1.2 Accuracy of Hlin( $k \times G \times \Delta f$ ) + +The accuracy requirements for the magnitude of Hlin( $k \times G \times \Delta f$ ) are the same as those for Hlog( $k \times G \times \Delta f$ ) in clause 11.4.1.2.1.1. + +There is no accuracy requirement for the phase of Hlin( $k \times G \times \Delta f$ ). + +#### 11.4.1.2.2 Accuracy of quiet line noise PSD per subcarrier group (QLN-ps) + +The downstream QLN( $f$ ) reference value for subcarrier group $k$ including subcarriers $i = k \times G$ to $((k + 1) \times G) - 1$ shall be defined as: + +$$\text{QLNps\_reference\_ds}(k \times G \times \Delta f) = \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{PSDps\_UR2}(i \times \Delta f)$$ + +where PSDps\_UR2( $i \times \Delta f$ ) is the PSD (in logarithmic scale) at frequency $i \times \Delta f$ measured at the U-R2 reference point in the downstream bands, after initialization of the line up to an O-P-QUIET stage, in which stage the VTU-O is frozen and the VTU-R subsequently replaced by an $R_N=100$ Ohm resistance. + +The upstream QLN( $f$ ) reference value for subcarrier group $k$ including subcarriers $i = k \times G$ to $((k + 1) \times G) - 1$ shall be defined as: + +$$\text{QLNps\_reference\_us}(k \times G \times \Delta f) = \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{PSDps\_UO2}(i \times \Delta f)$$ + +where PSDps\_UO2( $i \times \Delta f$ ) is the PSD (in logarithmic scale) at frequency $i \times \Delta f$ measured at the U-O2 reference point in the upstream bands, after initialization of the line up to an R-P-QUIET stage, in which stage the VTU-R is frozen and the VTU-O subsequently replaced by an $R_N=100$ Ohm resistance. + +NOTE 1 – The feature to freeze a VTU in a QUIET stage exists solely to allow a test bed to be constructed for the purpose of measuring the QLN( $f$ ) reference value. It applies only to specific transceivers serving as the 'transmit transceiver' of the test environment and is not a requirement for compliance with this Recommendation. + +The receiving VTU shall measure the QLN( $f$ ) values under the same loop, noise, temperature, and configuration settings as are used for measuring the QLN( $f$ ) reference values. + +The accuracy requirements for the downstream QLN( $k \times G \times \Delta f$ ) (ITU-T G.997.1 parameter QLNpsds) shall apply to the subcarrier groups in the same frequency bands and with the same loop impedance ( $Z_{loop}$ ) restrictions as where the downstream Hlog( $k \times G \times \Delta f$ ) accuracy requirements apply (see clause 11.4.1.1.2). + +The accuracy requirements for the upstream QLN( $k \times G \times \Delta f$ ) (ITU-T G.997.1 parameter QLNpsus) shall apply to the subcarrier groups in the same frequency bands and with the same loop impedance ( $Z_{loop}$ ) restrictions as where the upstream Hlog( $k \times G \times \Delta f$ ) accuracy requirements apply (see clause 11.4.1.1.2). + +Accuracy requirements outside these frequency ranges are for further study. + +NOTE 2 – Having such specified ranges for accuracy requirements avoids variations due to the tolerances and effects of the filtering at the low ends of the passband and of the effects of folding at the high end of the passband. + +For each subcarrier group where the accuracy requirement for downstream $QLN(k \times G \times \Delta f)$ applies (based on its subcarrier indexes only, and not considering restrictions related to its $Z_{loop}$ values), and where $QLNps\_reference\_ds(k \times G \times \Delta f)$ is above $-130$ dBm/Hz, a downstream $QLN(k \times G \times \Delta f)$ value different from the special value defined in clause 11.4.1.1.2 shall be reported. + +For each subcarrier group where the accuracy requirement for downstream $QLN(k \times G \times \Delta f)$ applies, and where $QLNps\_reference\_ds(k \times G \times \Delta f)$ is above $-130$ dBm/Hz, the absolute error between the downstream $QLN(k \times G \times \Delta f)$ and the $QLNps\_reference\_ds(k \times G \times \Delta f)$ shall be $\leq 3.0$ dB. To account for sinusoidal noise sources internal to the VTU-R, this requirement does not apply to up to 5 clusters of N consecutive subcarrier groups per 2.2 MHz bandwidth, which can be selected at the VTU-R vendor's discretion, with $N = 1 + \text{ceil}(W/G)$ and $W = 12$ . + +For each subcarrier group where the accuracy requirement for downstream $QLN(k \times G \times \Delta f)$ applies, and where $QLNps\_reference\_ds(k \times G \times \Delta f)$ is above $-130$ dBm/Hz, the sample variance of downstream $QLN(k \times G \times \Delta f)$ measurements (within a 10 minute measurement window, and under the same loop, noise, temperature, and configuration settings) shall be $\leq 0.5$ dB. To account for sinusoidal noise sources internal to the VTU-R, this requirement does not apply to up to 5 clusters of N consecutive subcarrier groups per 2.2 MHz bandwidth, which can be selected at the VTU-R vendor's discretion, with $N = 1 + \text{ceil}(W/G)$ and $W = 12$ . + +The accuracy requirements for downstream $QLN(k \times G \times \Delta f)$ shall apply to its measurement either during Initialization or in Loop Diagnostic mode. + +For each subcarrier group where the accuracy requirement for upstream $QLN(k \times G \times \Delta f)$ applies (based on its subcarrier indexes only, and not considering restrictions related to its $Z_{loop}$ values), and where $QLNps\_reference\_us(k \times G \times \Delta f)$ is above $-120$ dBm/Hz, an upstream $QLN(k \times G \times \Delta f)$ value different from the special value defined in clause 11.4.1.1.2 shall be reported. + +For each subcarrier group where the accuracy requirement for upstream $QLN(k \times G \times \Delta f)$ applies, and where $QLNps\_reference\_us(k \times G \times \Delta f)$ is above $-120$ dBm/Hz, the absolute error between the upstream $QLN(k \times G \times \Delta f)$ and the $QLNps\_reference\_us(k \times G \times \Delta f)$ shall be $\leq 3.0$ dB. To account for sinusoidal noise sources internal to the VTU-O, this requirement does not apply to up to 10 clusters of N consecutive subcarrier groups per 2.2 MHz bandwidth, which can be selected at the VTU-O vendor's discretion, with $N = 1 + \text{ceil}(W/G)$ and $W = 12$ . + +For each subcarrier group where the accuracy requirement for upstream $QLN(k \times G \times \Delta f)$ applies, and where $QLNps\_reference\_us(k \times G \times \Delta f)$ is above $-120$ dBm/Hz, the statistical sample variance of upstream $QLN(k \times G \times \Delta f)$ measurements (within a 10 minute measurement window, and under the same loop, noise, temperature, and configuration settings) shall be $\leq 0.5$ dB. To account for sinusoidal noise sources internal to the VTU-O, this requirement does not apply to up to 10 clusters of N consecutive subcarrier groups per 2.2 MHz bandwidth, which can be selected at the VTU-O vendor's discretion, with $N = 1 + \text{ceil}(W/G)$ and $W = 12$ . + +The accuracy requirements for upstream $QLN(k \times G \times \Delta f)$ shall apply to its measurement either during Initialization or in Loop Diagnostic mode. + +#### 11.4.1.2.3 Accuracy of signal-to-noise ratio per subcarrier group (SNR-ps) + +Noise PSD changes over time shall be reflected in the reported $SNR(k \times G \times \Delta f)$ . This clause defines accuracy requirements for the change in $SNR(k \times G \times \Delta f)$ over a time interval $[T1, T2]$ , relative to a reference value. The downstream and upstream reference values for subcarrier group $k$ including subcarriers $i = k \times G$ to $((k + 1) \times G) - 1$ are defined as: + +$$\Delta SNRps\_reference\_ds(k \times G \times \Delta f) = \text{Noise\_PSDps\_UR2\_T1}(k \times G \times \Delta f) - \text{Noise\_PSDps\_UR2\_T2}(k \times G \times \Delta f)$$ + +$$\Delta\text{SNRps\_reference\_us}(k \times G \times \Delta f) = \text{Noise\_PSDps\_UO2\_T1}(k \times G \times \Delta f) - \text{Noise\_PSDps\_UO2\_T2}(k \times G \times \Delta f)$$ + +where: + +- Noise\_PSDps\_UR2\_T1 is the stationary noise PSD (in dBm/Hz) present on the line at the U-R2 reference point at time instant T1, and for at least one minute before T1; +- Noise\_PSDps\_UR2\_T2 is the stationary noise PSD (in dBm/Hz) present on the line at the U-R2 reference point at time instant T2, and for at least one minute before T2; +- Noise\_PSDps\_UO2\_T1 is the stationary noise PSD (in dBm/Hz) present on the line at the U-O2 reference point at time instant T1, and for at least one minute before T1; +- Noise\_PSDps\_UO2\_T2 is the stationary noise PSD (in dBm/Hz) present on the line at the U-O2 reference point at time instant T2, and for at least one minute before T2. + +These four Noise\_PSDps's shall be measured by the same method as is used to measure the QLNps\_reference (see clause 11.4.1.1.2) and before the SNR measurements. Before the actual measurements of SNR, the two noise PSDs (for time T1 and T2) shall be measured while the transmitting VTU is frozen in a QUIET state. Then the transmitting VTU is allowed to enter SHOWTIME and the SNR measurements are made under the same two Noise\_PSDps's. The SNR measurements shall be made under the same loop and temperature conditions as the Noise\_PSDps measurements. + +The accuracy requirements for the downstream $\text{SNR}(k \times G \times \Delta f)$ (ITU-T G.997.1 parameter SNRpsds) shall apply to those subcarrier groups in the downstream passband where all of the following conditions hold: + +- Subcarriers in the subcarrier group are at least 50 kHz away from the lower and higher passband edge; +- $\text{bi\_T1}(i) > 0$ and $\text{bi\_T2}(i) > 0$ for at least one subcarrier $i$ in the subcarrier group ( $i$ between $k \times G$ and $(k+1) \times G - 1$ for subcarrier group $k$ ); +- $\text{Noise\_PSDps\_UR2\_T1}(k \times G \times \Delta f)$ and $\text{Noise\_PSDps\_UR2\_T2}(k \times G \times \Delta f)$ are larger than $-110$ dBm/Hz; +- $(\text{SNRps\_T1}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T1}(i))$ and $(\text{SNRps\_T2}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T2}(i))$ are both smaller than 40 dB, + +where: + +- $\text{gi\_T1}(i)$ and $\text{gi\_T2}(i)$ are the downstream fine gains (in dB) at time instants T1 and T2; +- $\text{bi\_T1}(i)$ and $\text{bi\_T2}(i)$ are the downstream bit loading at time instants T1 and T2; +- $\text{SNRps\_T1}(k \times G \times \Delta f)$ and $\text{SNRps\_T2}(k \times G \times \Delta f)$ are the downstream SNRs (in dB), measured during showtime, at time instants T1 and T2. + +The accuracy requirements for the upstream $\text{SNR}(k \times G \times \Delta f)$ (ITU-T G.997.1 parameter SNRpsus) shall apply to those subcarrier groups in the upstream passband where all of the following conditions hold: + +- Subcarriers in the subcarrier group are at least 50kHz away from the lower and higher passband edge; +- $\text{bi\_T1}(i) > 0$ and $\text{bi\_T2}(i) > 0$ , for at least one subcarrier $i$ in the subcarrier group ( $i$ between $k \times G$ and $(k+1) \times G - 1$ for subcarrier group $k$ ); +- $\text{Noise\_PSDps\_UO2\_T1}(k \times G \times \Delta f)$ and $\text{Noise\_PSDps\_UO2\_T2}(k \times G \times \Delta f)$ are larger than $-120$ dBm/Hz; + +- $(\text{SNRps\_T1}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T1}(i))$ and $(\text{SNRps\_T2}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T2}(i))$ are both smaller than 40 dB, + +where: + +- $\text{gi\_T1}(i)$ and $\text{gi\_T2}(i)$ are the upstream fine gains (in dB) at time instants T1 and T2; +- $\text{bi\_T1}(i)$ and $\text{bi\_T2}(i)$ are the upstream bit loading at time instants T1 and T2; +- $\text{SNRps\_T1}(k \times G \times \Delta f)$ and $\text{SNRps\_T2}(k \times G \times \Delta f)$ are the upstream SNRs (in dB), measured during showtime, at time instants T1 and T2. + +If the line does not re-initialize over a time period T1 to T2, the following requirements shall be met for downstream subcarrier groups where the $\text{SNR}(k \times G \times \Delta f)$ accuracy requirement applies: + +$$|(\text{SNRps\_T2}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T2}(i)) - (\text{SNRps\_T1}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T1}(i)) - \Delta \text{SNRps\_reference\_ds}(k \times G \times \Delta f)| \leq 0.8 \text{ dB}.$$ + +Accuracy requirements for downstream subcarrier groups where $(\text{SNRps\_T1} - \text{gi\_T1})$ or $(\text{SNRps\_T2} - \text{gi\_T2})$ is greater than 40 dB, are for further study. + +For each downstream subcarrier group where the $\text{SNR}(k \times G \times \Delta f)$ accuracy requirement applies, the sample variance of $\text{SNR}(k \times G \times \Delta f)$ measurements (expressed in dB and all samples taken within a 10 minute time interval, without line re-initialization in this time interval, and under the same loop, noise, temperature, and configuration settings) shall be equal to or smaller than 0.5, calculated as follows: + +$$\text{SNRps\_variance} \leq 0.5$$ + +where + +$$\text{SNRps\_variance} = \frac{1}{N} \left( \sum_{i=1}^N (\text{SNRps}(i) - \text{SNRps\_avg})^2 \right)$$ + +$$\text{SNRps\_avg} = \frac{1}{N} \left( \sum_{i=1}^N \text{SNRps}(i) \right)$$ + +If the line does not re-initialize over a time period T1 to T2, the following requirements shall be met for upstream subcarrier groups where the $\text{SNR}(k \times G \times \Delta f)$ accuracy requirement applies: + +$$|(\text{SNRps\_T2}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T2}(i)) - (\text{SNRps\_T1}(k \times G \times \Delta f) - \frac{1}{G} \sum_{i=kG}^{(k+1)G-1} \text{gi\_T1}(i)) - \Delta \text{SNRps\_reference\_us}(k \times G \times \Delta f)| \leq 0.8 \text{ dB}.$$ + +Accuracy requirements for upstream subcarrier groups where $(\text{SNRps\_T1} - \text{gi\_T1})$ or $(\text{SNRps\_T2} - \text{gi\_T2})$ is greater than 40 dB, are for further study. + +For each upstream subcarrier group where the $\text{SNR}(k \times G \times \Delta f)$ accuracy requirement applies, the sample variance of $\text{SNR}(k \times G \times \Delta f)$ measurements (expressed in dB and all samples taken within a 10 minute interval, without line re-initialization in this time interval, and under the same loop, noise, temperature, and configuration settings) shall be equal to or smaller than 0.5, calculated as follows: + +$$SNRps\_variance \leq 0.5$$ + +where + +$$SNRps\_variance = \frac{1}{N} \left( \sum_{i=1}^N (SNRps(i) - SNRps\_avg)^2 \right)$$ + +$$SNRps\_avg = \frac{1}{N} \left( \sum_{i=1}^N SNRps(i) \right)$$ + +NOTE – In verification tests, noise changes should be applied gradually over time, and not simultaneously at the U-O2 and U-R2 reference point, as not to force a re-initialization of the line. + +#### 11.4.1.2.4 Accuracy of loop attenuation per band (*LATN-pb*) + +The downstream LATN reference value shall be defined as follows: + +$$LATN\_reference\_ds(m) = -10 \times \log_{10} \left( \frac{\sum_{k=n1}^{n2} |H\_reference\_ds(k \times \Delta f)|^2}{N\_D(m)} \right)$$ + +In the equation above, $N\_D(m)$ (the number of subcarriers in the $m$ th downstream band) = $n2 - n1 + 1$ where $n1$ and $n2$ are the indices of the first and the last subcarriers of this band, respectively, and $H\_reference\_ds(k \times \Delta f)$ is defined as: + +$$|H\_reference\_ds(k \times \Delta f)|^2 = 10^{HLOG\_reference\_ds(k \times \Delta f)/10} = 10^{(MREFPSDds(k \times \Delta f) - PSD\_UR2(k \times \Delta f))/10},$$ + +where $PSD\_UR2(k \times \Delta f)$ is the PSD measured at the U-R2 reference point with the VTU-O connected to the loop and frozen in the O-P-MEDLEY stage of initialization with the SOC in the O-IDLE state, and with the VTU-R replaced by an $R_N=100$ Ohm resistance terminating the loop. + +If one or more $H\_reference\_ds(f)$ values could not be measured because they are out of the transmitter SUPPORTEDCARRIERS set (see clause 11.4.1.1.1), then the $LATN\_D(m)$ shall be calculated as an average of $H(f)$ values over the number of subcarriers for which valid values of $H(f)$ are available. Also, + +The upstream LATN reference value shall be defined as follows: + +$$LATN\_reference\_us(m) = -10 \times \log_{10} \left( \frac{\sum_{k=n1}^{n2} |H\_reference\_us(k \times \Delta f)|^2}{N\_U(m)} \right)$$ + +with $N\_U(m)$ (the number of subcarriers in the $m$ th upstream band) = $n2 - n1 + 1$ where $n1$ and $n2$ are the indices of the first and the last subcarriers of this band, respectively. The value of $H\_reference\_ds(k \times \Delta f)$ is defined as: + +$$|H\_reference\_us(k \times \Delta f)|^2 = 10^{HLOG\_reference\_us(k \times \Delta f)/10} = 10^{(MREFPSDus(k \times \Delta f) - PSD\_UO2(k \times \Delta f))/10}$$ + +where $PSD\_UO2(k \times \Delta f)$ is the PSD measured at the U-O2 reference point with the VTU-R connected to the loop and frozen in the R-P-MEDLEY stage of initialization with the SOC in the R-IDLE state, and with the VTU-O replaced by an $R_N=100$ Ohm resistance terminating the loop. + +If one or more $H\_reference\_us(f)$ values could not be measured because they are out of the transmitter SUPPORTEDCARRIERS set (see clause 11.4.1.1.1), then the $LATN\_U(m)$ shall be calculated as an average of $H(f)$ values over the number of subcarriers for which valid values of $H(f)$ are available. + +NOTE – The feature to freeze a VTU in the MEDLEY stage of initialization exists solely to allow a test bed to be constructed for the purpose of measuring the $H(f)$ reference values. It applies only to specific transceivers serving as the 'transmit transceiver' of the test environment and is not a requirement for compliance with this Recommendation. + +The receiving VTU shall measure the LATN values under the same loop, noise, temperature, and configuration settings that are used for measuring the LATN reference values. + +For all downstream bands, $m$ , that are active during loop diagnostics or initialization, the absolute error between $LATN\_D(m)$ and $LATN\_reference\_ds(m)$ shall be equal to or smaller than 3 dB. + +The accuracy requirements for downstream $LATN\_D(m)$ shall apply to its measurement either during Initialization or in Loop Diagnostic mode. + +For all upstream bands, $m$ , that are active during loop diagnostics or initialization, the absolute error between $LATN\_U(m)$ and $LATN\_reference\_us(m)$ shall be equal to or smaller than 3 dB. + +The accuracy requirements for upstream $LATN\_U(m)$ shall apply to its measurement either during Initialization or in Loop Diagnostic mode. + +#### 11.4.1.2.5 Accuracy of signal attenuation (SATN) + +The downstream SATN reference value shall be defined as follows: + +$$SATN\_reference\_ds(m) = TXpower\_dBm\_reference\_ds(m) - RXpower\_dBm\_reference\_ds(m)$$ + +The $TXpower\_dBm\_reference\_ds(m)$ is defined as: + +$$TXpower\_dBm\_reference\_ds(m) = 10 \times \log_{10} \Delta f + 10 \times \log_{10} \left( \sum_{i \in MEDLEYds \cap DS(m)} \left( 10^{\frac{MREFPSD[i]}{10}} \times g_i^2 \right) \right)$$ + +where $MEDLEYds \cap DS(m)$ denotes all subcarriers of the $MEDLEYds$ set that fall into the $m$ th downstream band, $MREFPSD[i]$ is the value of $MREFPSD$ for subcarrier $i$ in dBm/Hz, $g_i$ is as defined in clause 11.4.1.1.5, and $\Delta f$ is the subcarrier spacing in Hz. + +The $RXpower\_dBm\_reference\_ds(m)$ is defined as: + +$$RXpower\_dBm\_reference\_ds(m) = 10 \times \log_{10} \left( \sum_{i \in MEDLEYds \cap DS(m)} \left( 10^{\frac{PSD\_UR2(i \times \Delta f)}{10}} \times g_i^2 \right) \right)$$ + +where $PSD\_UR2(i \times \Delta f)$ is the PSD measured at the U-R2 reference point with the VTU-O connected to the loop and frozen in the O-P-MEDLEY stage of initialization with the SOC in the O-IDLE state, and with the VTU-R replaced by an $R_N=100$ Ohm resistance terminating the loop. + +The upstream SATN reference value shall be defined as follows: + +$$SATN\_reference\_us(m) = TXpower\_dBm\_reference\_us(m) - RXpower\_dBm\_reference\_us(m)$$ + +The $TXpower\_dBm\_reference\_us(m)$ is defined as: + +$$TXpower\_dBm\_reference\_us(m) = 10 \times \log_{10} \Delta f + 10 \times \log_{10} \left( \sum_{i \in MEDLEYus \cap US(m)} \left( 10^{\frac{MREFPSD[i]}{10}} \times g_i^2 \right) \right)$$ + +where $MEDLEYus \cap US(m)$ denotes all subcarriers of the $MEDLEYus$ set that fall into the $m$ th upstream band, $MREFPSD[i]$ is the value of $MREFPSD$ for subcarrier $i$ in dBm/Hz, $g_i$ is as defined in clause 11.4.1.1.5, and $\Delta f$ is the subcarrier spacing in Hz. + +The $RXpower\_dBm\_reference\_us(m)$ is defined as: + +$$RXpower\_dBm\_reference\_us(m) = 10 \times \log_{10} \left( \sum_{i \in MEDLEYus \cap US(m)} \left( 10^{\frac{PSD\_UO2(i \times \Delta f)}{10}} \times g_i^2 \right) \right)$$ + +where $PSD\_UO2(i \times \Delta f)$ is the PSD measured at the U-O2 reference point with the VTU-R connected to the loop and frozen in the R-P-MEDLEY stage of initialization with the SOC in the R-IDLE state, and with the VTU-O replaced by an $R_N=100$ Ohm resistance terminating the loop. + +NOTE – The feature to freeze a VTU in the MEDLEY stage of initialization exists solely to allow a test bed to be constructed for the purpose of measuring the $H(f)$ reference values. It applies only to specific transceivers serving as the 'transmit transceiver' of the test environment and is not a requirement for compliance with this Recommendation. + +The receiving VTU shall measure the SATN values under the same loop, noise, temperature and configuration settings that are used for measuring the SATN reference values. + +For all downstream bands, $m$ , that are active during loop diagnostics or initialization, the absolute error between $SATN\_D(m)$ and $SATN\_reference\_ds(m)$ shall be equal to or smaller than 3 dB. + +The accuracy requirements for downstream $SATN\_D(m)$ shall apply to its measurement after Initialization during showtime. + +For all upstream bands, $m$ , that are active during loop diagnostics or initialization, the absolute error between $SATN\_U(m)$ and $SATN\_reference\_us(m)$ shall be equal to or smaller than 3 dB. + +The accuracy requirements for upstream $SATN\_U(m)$ shall apply to its measurement after Initialization during showtime. + +#### 11.4.1.2.6 Accuracy of signal-to-noise ratio margin (*SNRM*) + +For further study. + +#### 11.4.1.2.7 Accuracy of attainable net data rate (*ATTNDR*) + +For further study. + +#### 11.4.1.2.8 Accuracy of actual aggregate transmit power (*ACTATP*) + +The VTU-O near-end ACTATP reference value shall be defined as follows: + +$$ACTATP\_reference\_UO2 = \text{sum\_over\_all\_frequencies} [PSDps\_UO2(i)],$$ + +where $PSDps\_UO2(i)$ is the downstream PSD measured at the U-O2 reference point, after initialization of the line up to the SHOWTIME state, in which state the VTU-O is frozen and the VTU-O subsequently connected to an $R_N=100$ Ohms. + +The VTU-R near-end ACTATP reference value shall be defined as follows: + +$$ACTATP\_reference\_UR2 = \text{sum\_over\_all\_frequencies} [PSDps\_UR2(i)]$$ + +where $PSDps\_UR2(i)$ is the upstream PSD measured at the U-R2 reference point, after initialization of the line up to the SHOWTIME state, in which state the VTU-R is frozen and the VTU-R subsequently connected to an $R_N=100$ Ohms. + +NOTE 1 – The ACTATP should be measured first. Subsequently, the VTU should be frozen in SHOWTIME and the $PSDps\_Ux$ should then be measured without re-initialization. + +NOTE 2 – The measurement of the $PSDps\_Ux$ involves freezing in SHOWTIME of the transceiver under test. Specification of special test modes for the transceiver under test is outside the scope of this Recommendation. + +The absolute error between the VTU-O near-end $ACTATP\_ds$ and the $ACTATP\_reference\_UO2$ shall be equal to or smaller than 1.0 dB. + +The sample variance of the VTU-O near-end $ACTATP\_ds$ measurements (all samples taken over a 10 minutes time interval, without line re-initialization and bit/gain-swaps in this time interval, and + +under the same loop, noise, temperature, and configuration settings) shall be equal to or smaller than 0.5 dB. + +NOTE 3 – The ACTATP\_ds samples are to be taken after sufficient time is allowed after initialization for bit and gain swaps to stabilize. + +The absolute error between the VTU-R near-end ACTATP\_us and the ACTATP\_reference\_UR2 shall be equal to or smaller than 1.0 dB. + +The sample variance of the VTU-R near-end ACTATP\_us measurements (all samples taken over a 10 minute time interval, without line re-initialization and bit/gain-swaps in this time interval, and under the same loop, noise, temperature, and configuration settings) shall be equal to or smaller than 0.5 dB. + +NOTE 4 – The ACTATP\_us samples are to be taken after sufficient time is allowed after initialization for bit and gain swaps to stabilize. + +## 11.4.2 Configuration parameters + +### 11.4.2.1 Transmitter-referred virtual noise PSD + +This clause describes the transmitter-referred virtual noise PSD parameter TXREFVN, used only in the optional SNR margin mode SNRM\_MODE = 2, SNRM\_MODE = 4, and SNRM\_MODE=5. + +#### 11.4.2.1.1 Definition of parameter TXREFVN + +Configuration parameter TXREFVN defines the transmitter-referred virtual noise PSD to be used in determining the SNR margin. + +For SNRM\_MODE = 2 and SNRM\_MODE = 4, the CO-MIB shall provide a TXREFVN parameter set for each utilized band. + +NOTE – For SNRM\_MODE=5, the TXREFVN parameter provided by the CO-MIB may be taken into account by the VTU-O to determine the initial value of TXREFSAVN (see clause 11.4.1.1.6.1.5). + +The transmitter-referred virtual noise PSD in the CO-MIB shall be specified by a set of breakpoints. + +Each breakpoint shall consist of a subcarrier index $t_n$ and a noise PSD (expressed in dBm/Hz). The TXREFVN parameter for each utilized band shall be a set of breakpoints that are represented by $[(t_1, PSD_1), (t_2, PSD_2), \dots, (t_n, PSD_n), (t_{NBP}, PSD_{NBP})]$ , where $t_1$ and $t_{NBP}$ are, respectively, the lower and higher band edge frequencies of the band. + +The subcarrier indices $t_i$ shall be coded in the CO-MIB as unsigned integers in the range from $t_1 = \text{roundup}(f_x/Df)$ to $t_{NBP} = \text{rounddown}(f_{x+1}/Df)$ , where $f_x$ , $f_{x+1}$ are the low and the high band separating frequencies determined by the applied band plan and specified in clause 7.1, and $Df = 4.3125$ kHz. The breakpoints shall be defined so that $t_n < t_{n+1}$ for $n = 1$ to $N - 1$ ; the frequency $f_n$ corresponding to the index $t_n$ can be found as: $f_n = t_n \times Df$ . The value of $Df$ is independent of the subcarrier spacing $\Delta f$ used for DMT modulation. When the VTU operates with 8.625 kHz subcarrier spacing, all odd values of $t_i$ shall be converted by the VTU, by rounding down to the next lower even value, and values $t_1$ and $t_{NBP}$ shall be rounded (up and down, respectively) to even values. + +The values for the transmitter-referred virtual noise PSD shall be coded as 8-bit unsigned integers representing virtual noise PSDs from $-40$ dBm/Hz (coded as 0) to $-140$ dBm/Hz (coded as 200), in steps of 0.5 dBm/Hz. Values from 201 to 255, inclusive, correspond to a virtual noise PSD of zero Watt/Hz (minus infinity dBm/Hz). + +The maximum number of breakpoints is 32 in the downstream and 16 in the upstream. + +The parameter in the downstream direction is TXREFVNd, and the parameter in the upstream direction is TXREFVNus. + +NOTE – TXREFVN is configured via the ITU-T G.997.1 parameter VN, whose interpretation depends on the value of SNRM\_MODE. + +#### 11.4.2.1.2 Use of parameter TXREFVN + +The transmitter-referred virtual noise PSD to be used by the transceiver for calculation of the SNR margin for each subcarrier $i$ , shall be obtained by linear interpolation in dB on a linear frequency scale as follows: + +$$TX\_referred\_Virtual\_Noise\_PSD(i) = PSD_n + (PSD_{n+1} - PSD_n) \times \frac{\left(\frac{i \cdot \Delta f}{Df}\right) - t_n}{t_{n+1} - t_n} \quad t_n < \left(\frac{i \cdot \Delta f}{Df}\right) \leq t_{n+1}$$ + +where $\Delta f$ is the actual subcarrier spacing used by the DMT modulation. + +In downstream, the breakpoints ( $t_i$ , $PSD_i$ ) are those communicated to the VTU-R in O-SIGNATURE and are a combination of the configuration parameter TXREFVNs and the configuration parameter TXRFVNSFs as described in clause 11.4.2.5. + +In upstream, the breakpoints ( $t_i$ , $PSD_i$ ) are equal to the breakpoints of the configuration parameter TXREFVNs as in the CO-MIB. + +The near-end transceiver should apply the Received\_Virtual\_Noise\_PSD (see clause 11.4.1.1.6.1.2) at the constellation decoder point (i.e., the transceiver does not need to account for DFT leakage effects from one subcarrier to another subcarrier). All effects are to be taken into account in the setting of the TXREFVN in the CO-MIB. + +NOTE 1 – The above method is equivalent to the near-end transceiver calculating its bit loading using the following Virtual\_Noise\_SNR for the subcarrier with index $i$ , at the constellation decoder (all terms are expressed in dB): + +$$Virtual\_Noise\_SNR(i) = S\_tx(i) - N\_tx(i) + 20 \times \log_{10}(g_i)$$ + +where: + +$$S\_tx(i) = MREFPSD(i)$$ + +$$N\_tx(i) = TX\_referred\_Virtual\_Noise\_PSD(i)$$ + +and MREFPSD( $i$ ) is the MEDLEY reference PSD value at the far-end transmitter for the subcarrier with index $i$ , obtained by interpolation of the breakpoints of the MEDLEY reference PSD (MREFPSD) information exchanged in the O-PRM and R-PRM messages during initialization. + +TX\_referred\_Virtual\_Noise\_PSD( $i$ ) is the transmitter-referred virtual noise PSD value for subcarrier with index $i$ , obtained by interpolation of the breakpoints of TXREFVN sent in the O-SIGNATURE message during initialization. + +$g_i$ is the gain adjuster for the subcarrier with index $i$ as defined in clause 10.3.4. + +NOTE 2 – Improper setting of TXREFVN can interact with the setting of one or more of the following parameters: maximum net data rate, downstream maximum SNR margin, impulse noise protection, and maximum interleaving delay. This interaction can result in high levels of transmit power that can lead to high crosstalk experienced by DSLs on other pairs in the same binder. + +#### 11.4.2.2 INM procedure and control parameters + +This clause describes the INM procedure and associated INM control parameters. + +##### 11.4.2.2.1 INM procedure + +Figure 11-5 shows the INM functional block diagram. + +![Figure 11-5 – Impulse noise monitor functional block diagram. The diagram shows a flow from left to right: Impulse noise sensor (INS) outputs 'Indication of severely degraded data symbols' to a 'Cluster indicator'. The 'Cluster indicator' outputs to two parallel blocks: 'Eq INP generation' and 'IAT generation'. Both of these blocks output to a combined block 'Eq INP and IAT anomalies generation'. This block outputs 'Anomalies' to 'INM counters'. A dashed line separates the 'Eq INP and IAT anomalies generation' block from the 'INM counters' block. The text 'G.993.2(06)Amd2_F11.5' is at the bottom right.](2fa686ed8033ac35efddee0c7be47d59_img.jpg) + +``` + +graph LR + INS[Impulse noise sensor (INS)] -- "Indication of severely degraded data symbols" --> CI[Cluster indicator] + CI --> EQ[Eq INP generation] + CI --> IAT[IAT generation] + EQ --> EQIAT[Eq INP and IAT anomalies generation] + IAT --> EQIAT + EQIAT -- "Anomalies" --> INM[INM counters] + +``` + +Figure 11-5 – Impulse noise monitor functional block diagram. The diagram shows a flow from left to right: Impulse noise sensor (INS) outputs 'Indication of severely degraded data symbols' to a 'Cluster indicator'. The 'Cluster indicator' outputs to two parallel blocks: 'Eq INP generation' and 'IAT generation'. Both of these blocks output to a combined block 'Eq INP and IAT anomalies generation'. This block outputs 'Anomalies' to 'INM counters'. A dashed line separates the 'Eq INP and IAT anomalies generation' block from the 'INM counters' block. The text 'G.993.2(06)Amd2\_F11.5' is at the bottom right. + +**Figure 11-5 – Impulse noise monitor functional block diagram** + +The INS indicates whether a data symbol is severely degraded or not. A data symbol is considered to be severely degraded when it would lead to severe errors on the gamma interface when there would be no impulse noise protection (i.e., RS only used for coding gain). The implementation details for this sensor are vendor-discretionary. + +NOTE 1 – Performance requirements for the INS are for further study. + +If a sync symbol occurs between two data symbols (severely degraded or not), the INS shall disregard it. + +NOTE 2 – If a sync symbol occurs between two groups of respectively N1 and N2 consecutive severely degraded data symbols, the two groups will form a single group of consecutive severely degraded data symbols of length N1 + N2 data symbols. + +The cluster indicator indicates short groups of severely degraded data symbols as clusters. The cluster can contain a single severely degraded data symbol, a group of consecutive severely degraded data symbols, or several groups of one or more consecutive severely degraded data symbols with gaps between the groups. + +The cluster indicator shall use the following rule to identify the cluster. A gap is defined as a group of non-severely degraded data symbols in-between two severely degraded data symbols. A cluster is defined as the largest group of consecutive data symbols, starting and ending with a severely degraded data symbol, containing severely degraded data symbols, separated by gaps smaller than or equal to INMCC (the cluster continuation parameter, see clause 11.4.2.2.4). + +As a consequence of the above definition of a cluster, each cluster starts with a severely degraded data symbol preceded by a gap larger than INMCC and ends with a severely degraded data symbol followed by a gap larger than INMCC, while gaps inside the cluster are all smaller than or equal to INMCC. + +In the Eq INP generation block, the "equivalent INP" of the cluster is generated. For each cluster, the following characteristics shall be determined: + +- The impulse noise cluster length (INCL), defined as the number of data symbols from the first to the last severely degraded data symbol in the cluster; +- The impulse noise cluster degraded data symbols (INCD), defined as the number of severely degraded data symbols in the cluster; +- The impulse noise cluster number of gaps (INCG), defined as the number of gaps in the cluster, with gap as defined above. + +Depending on the value of the control parameter INM\_INPEQ\_MODE, the equivalent INP is generated as: + +- $INM\_INPEQ\_MODE = 0: \quad INP\_eq = INCL$ with $INMCC = 0$ +- $INM\_INPEQ\_MODE = 1: \quad INP\_eq = INCL$ with $INMCC$ as configured (see clause 11.4.2.2.4) + +- INM\_INPEQ\_MODE = 2: $INP\_eq = INCD$ with INMCC as configured (see clause 11.4.2.2.4) +- INM\_INPEQ\_MODE = 3: + +$$\text{For INCG} < (8 \times \text{erasuregain}): INP\_eq = \min \left( INCL, \text{ceil} \left[ INCD \times \left( \frac{1}{1 - \frac{INCG}{8 \times \text{erasuregain}}} \right) \right] \right)$$ + +For INCG $\geq (8 \times \text{erasuregain})$ : $INP\_eq = INCL$ + +with INMCC as configured (see clause 11.4.2.2.4) + +where the erasure gain is defined as: + +$$\text{erasuregain} = \frac{INP}{INP\_no\_erasure} \text{ with INP, and } INP\_no\_erasure \text{ as defined in clause 9.6.}$$ + +NOTE 3 – In case the bit "INP\_no\_erasure\_required" (bit 8 in the "impulse noise protection and dynamic interleaver reconfiguration" field in Table 12-51, clause 12.3.5.2.1.1) is set, the erasure gain is equal to 1. + +- INM\_INPEQ\_MODE = 4: In this mode, the value of INP\_eq shall correspond with the VTU's own estimate (i.e., VTU-R's estimate in the downstream, VTU-O's estimate in the upstream) of the INP\_min setting required to provide error-free operation for the cluster, with INMCC as configured (see clause 11.4.2.2.4). The method of computation of the VTU's own estimate is vendor-discretionary. For INM\_INPEQ\_MODE = 4 only, if INMCC is set to 64, the VTU shall use its own method for cluster indication. If INMCC < 64, the VTU shall use the cluster indicator as described in this clause for the INM\_INPEQ\_MODE = 1, 2 and 3. + +Anomalies are generated for several values of INP\_eq, as defined in clause 11.3.4.1. The counters of these anomalies represent the INP\_eq histogram. + +In the IAT generation block, the inter-arrival time (IAT) is generated as the number of data symbols from the start of a cluster to the start of the next cluster. If sync symbols occur between two clusters, they shall not be counted in the IAT. Anomalies are generated for several ranges of inter arrival time, as defined in clause 11.3.4.3. The counters of these anomalies represent the IAT histogram. + +For every data symbol, the total measurement count INMAME is increased by 1. + +#### 11.4.2.2.2 Definition of parameter INMIATO + +Configuration parameter INMIATO defines the INM inter-arrival time offset for the IAT anomaly generation in order to determine in which bin of the inter-arrival time histogram the IAT is reported (see clause 11.3.4.3). + +The CO MIB shall provide the value for the INMIATO parameter. The parameter in the downstream direction is INMIATODs, and the parameter in the upstream direction is INMIATOUS. + +The valid values for INMIATO in both directions range from 3 to 511 DMT symbols in steps of 1 DMT symbol. If the VTU supports the INM facility, it shall support all valid values. + +Upon entering the first showtime after power-up, the VTU-R shall use a default value of INMIATODs = 3. During showtime, this value may be overwritten by the VTU-O using an INM facility command defined in clause 11.2.3.13. A link state transition shall not affect the INMIATODs value (e.g., not reset the value to the default value). + +The VTU-O shall use the current value of INMIATOUS stored in the CO MIB. + +#### 11.4.2.2.3 Definition of parameter INMIATS + +Configuration parameter INMIATS defines the INM inter-arrival time step for the IAT anomaly generation in order to determine in which bin of the inter-arrival time histogram the IAT is reported (see clause 11.3.4.3). + +The CO MIB shall provide the value for the INMIATS parameter. The parameter in the downstream direction is INMIATSds, and the parameter in the upstream direction is INMIATSus. + +The valid values for INMIATS range from 0 to 7 in steps of 1. If the VTU supports the INM facility, it shall support all valid values. + +Upon entering the first showtime after power-up, the VTU-R shall use a default value of INMIATSds = 0. During showtime, this value may be overwritten by the VTU-O using an INM facility command defined in clause 11.2.3.13. A link state transition shall not affect the INMIATSds value (e.g., not reset the value to the default value). + +The VTU-O shall use the current value of INMIATSus stored in the CO MIB. + +#### 11.4.2.2.4 Definition of parameter INMCC + +Configuration parameter INMCC defines the INM cluster continuation value to be used in the cluster indication process described in clause 11.4.2.2.1. If INM\_INPEQ\_MODE = 0, INMCC is equal to zero, independent of the CO MIB setting. If INM\_INPEQ\_MODE > 0, the CO MIB shall provide the value for the INMCC parameter. The parameter in the downstream direction is INMCCds, and the parameter in the upstream direction is INMCCus. + +The valid values for INMCC range from 0 to 64 DMT symbols in steps of 1 DMT symbol. If the VTU supports the INM facility, it shall support INMCC = 0. If the VTU supports the INM facility, and supports any INM\_INPEQ\_MODE > 0, it shall support all valid values. + +Upon entering the first showtime after power-up, the VTU-R shall use a default value of INMCCds = 0. During showtime, this value may be overwritten by the VTU-O using an INM facility command defined in clause 11.2.3.13. + +A link state transition shall not affect the INMCCds value (e.g., not reset the value to the default value). + +The VTU-O shall use the current value of INMCCus stored in the CO MIB. + +#### 11.4.2.2.5 Definition of parameter INM\_INPEQ\_MODE + +Configuration parameter INM\_INPEQ\_MODE defines the way of computation of equivalent INP, as defined in clause 11.4.2.2.1. The CO MIB shall provide the value for the INM\_INPEQ\_MODE parameter. The parameter in the downstream direction is INM\_INPEQ\_MODEds, and the parameter in the upstream direction is INM\_INPEQ\_MODEus. + +The valid values for INM\_INPEQ\_MODE are 0, 1, 2, 3 and 4. If the VTU supports the INM facility, it shall support INM\_INPEQ\_MODE = 0. All other modes are optional. If the VTU supports any INM\_INPEQ\_MODE > 0, it shall support at least INM\_INPEQ\_MODE = 1, 2 and 3. + +Upon entering the first showtime after power-up, the VTU-R shall use a default value of INM\_INPEQ\_MODEds = 0. During showtime, this value may be overwritten by the VTU-O using an INM facility command defined in clause 11.2.3.13. + +A link state transition shall not affect the INM\_INPEQ\_MODE value (e.g., not reset the value to the default value). + +The VTU-O shall use the current value of INM\_INPEQ\_MODEus stored in the CO MIB. + +#### 11.4.2.2.6 Definition of parameter INM\_INPEQ\_FORMAT + +Configuration parameter INM\_INPEQ\_FORMAT defines the way the scale is configured for the INM\_INPEQ histogram, as defined in clause 11.3.4.1. The CO MIB shall provide the value for the INM\_INPEQ\_FORMAT parameter. The parameter in the downstream direction is INM\_INPEQ\_FORMATds, and the parameter in the upstream direction is INM\_INPEQ\_FORMATus. + +The valid values for INM\_INPEQ\_FORMAT are 0 and 1. If the VTU supports the INM facility, it shall support INM\_INPEQ\_FORMAT = 0 and may support INM\_INPEQ\_FORMAT = 1. + +Upon entering the first showtime after power-up, the VTU-R shall use a default value of INM\_INPEQ\_FORMAT = 0. During showtime, this value may be overwritten by the VTU-O using an INM facility command defined in clause 11.2.3.13 if the VTU-R supports INM\_INPEQ\_FORMAT = 1. + +A link state transition shall not affect the INM\_INPEQ\_FORMAT value (e.g., not reset the value to the default value). + +The VTU-O shall use the current value of INM\_INPEQ\_FORMATus stored in the CO-MIB. + +#### 11.4.2.3 Receiver-referred virtual noise PSD + +This clause describes the receiver-referred virtual noise PSD parameter RXREFVN, used only in the optional SNR margin mode SNRM\_MODE = 3 and SNRM\_MODE=4. + +##### 11.4.2.3.1 Definition of parameter RXREFVN + +Configuration parameter RXREFVN defines the receiver-referred virtual noise PSD to be used in determining the SNR margin. + +For SNRM\_MODE=3 and SNRM\_MODE=4, the CO-MIB shall provide a RXREFVN parameter set for each utilized band. + +The receiver-referred virtual noise PSD in the CO-MIB shall be specified by a set of breakpoints. Each breakpoint shall consist of a subcarrier index $t_n$ and a noise PSD value (expressed in $\text{dBm/Hz}$ ). The RXREFVN parameter for each band shall be a set of breakpoints that are represented by $[(t_1, PSD_1), (t_2, PSD_2), \dots, (t_n, PSD_n), \dots, (t_{NBP}, PSD_{NBP})]$ , where $t_1$ and $t_{NBP}$ are, respectively, the lower and higher band edge frequencies of the band. The VTU shall ignore any frequency information that does not belong to the utilized (upstream) bands. + +The subcarrier indices $t_i$ shall be coded in the CO-MIB as unsigned integers in the range from $t_1 = \text{roundup}(f_x/Df)$ to $t_{NBP} = \text{rounddown}(f_{x+1}/Df)$ , where $f_x$ , $f_{x+1}$ are the low and the high band separating frequencies determined by the applied band plan and specified in clause 7.1, and $Df = 4.3125 \text{ kHz}$ . The breakpoints shall be defined so that $t_n < t_{n+1}$ for $n = 1$ to $N - 1$ ; the frequency $f_n$ corresponding to the index $t_n$ can be found as: $f_n = t_n \times Df$ . The value of $Df$ is independent of the subcarrier spacing $\Delta f$ used for DMT modulation. When the VTU operates with 8.625 kHz subcarrier spacing, all odd values of $t_i$ shall be converted by the VTU, by rounding down to the next lower even value, and values $t_1$ and $t_{NBP}$ shall be rounded (up and down, respectively) to even values. + +The values for the virtual noise PSD shall be coded as 8-bit unsigned integers representing virtual noise PSD values from $-40 \text{ dBm/Hz}$ (coded as 0) to $-140 \text{ dBm/Hz}$ (coded as 200), in steps of $0.5 \text{ dBm/Hz}$ . Values from 201 to 255, inclusive, correspond to a virtual noise PSD of zero Watt/Hz (minus infinity $\text{dBm/Hz}$ ). + +The maximum number of breakpoints is 16. + +The parameter in the upstream direction is RXREFVNUus. + +NOTE – RXREFVN is configured via the ITU-T G.997.1 parameter VN, whose interpretation depends on the value of SNRM\_MODE. + +### 11.4.2.3.2 Use of parameter RXREFVN + +For each frequency band, the receiver-referred virtual noise PSD, for each subcarrier $i$ , shall be obtained by linear interpolation in $dB$ on a linear frequency scale as follows: + +$$RX\_referred\_Virtual\_Noise\_PSD(i) = PSD_n + (PSD_{n+1} - PSD_n) \times \frac{\left(\frac{i \cdot \Delta f}{Df}\right) - t_n}{t_{n+1} - t_n} \quad t_n < \left(\frac{i \cdot \Delta f}{Df}\right) \leq t_{n+1}$$ + +where $\Delta f$ is the actual subcarrier spacing used by the DMT modulation. + +In SNRM\_MODE=3, the breakpoints $(t_i, PSD_i)$ are equal to the breakpoints of the configuration parameter RXREFVNus as in the CO-MIB. + +In SNRM\_MODE=4, the breakpoints $(t_i, PSD_i)$ are a combination of the configuration parameter RXREFVNus and the configuration parameter RXREFVNSFus as described in clause 11.4.2.4. + +The near-end transceiver should apply the Received\_Virtual\_Noise\_PSD (see clause 11.4.1.1.6.1.3) over the upstream frequencies at the constellation decoder point (i.e., the transceiver does not need to account for DFT leakage effects from one subcarrier to another subcarrier). All effects are to be taken into account in the setting of the RXREFVN in the CO-MIB. + +NOTE 1 – The above method is equivalent to the near-end transceiver calculating its bit loading using the following Virtual\_Noise\_SNR for the subcarrier with index $i$ , at the constellation decoder (all terms are expressed in $dB$ ): + +$$Virtual\_Noise\_SNR(i) = S\_rx(i) - N\_rx(i)$$ + +where: + +$$S\_tx(i) = \text{Actual\_Received\_Signal\_PSD} = |H_{RXfilter}(f)|^2 + \text{Actual\_Received\_Signal\_at\_U\_interface}$$ + +$$N\_tx(i) = \text{Received\_Virtual\_Noise\_PSD} = |H_{RXfilter}(f)|^2 + RXREFVN + RXREFVNSF$$ + +NOTE 2 – Improper setting of RXREFVN and RXREFVNSF can interact with the setting of one or more of the following parameters: maximum net data rate, downstream maximum SNR margin, impulse noise protection, and maximum interleaving delay. This interaction can result in high levels of transmit power that can lead to high crosstalk experienced by DSLs on other pairs in the same binder. + +### 11.4.2.4 Receiver-referred virtual noise scaling factor + +This clause describes the receiver-referred virtual noise scaling factor parameter RXREFVNSF, used only in the optional SNR margin mode SNRM\_MODE = 4. + +Configuration parameter RXREFVNSF defines the receiver-referred virtual noise scaling factor to be used together with the receiver-referred virtual noise PSD in determining the SNR margin. + +The CO-MIB shall provide an upstream RXREFVNSF parameter when SNRM\_MODE = 4. + +The values for the receiver-referred virtual noise PSD scaling factor shall be coded as 8-bit signed integers representing scaling factors from $-64.0$ $dB$ (coded as $-128$ ) to $63.5$ $dB$ (coded as $127$ ), in steps of $0.5$ $dB$ . + +The parameter in the upstream direction is RXREFVNSFus. + +The VTU-O shall combine the value of the configuration parameter RXREFVNSFus as in the CO-MIB with the value of the configuration parameter RXREFVNus as in the CO-MIB to a control parameter RXREFVNus as follows: + +Control parameter RXREFVNus in $dBm/Hz$ = configuration parameter RXREFVNus in $dBm/Hz$ + configuration parameter RXREFVNSFus in $dB$ . + +#### 11.4.2.5 Transmitter-referred virtual noise scaling factor + +This clause describes the transmitter-referred virtual noise scaling factor parameter TXREFVNSF, used only in the optional SNR margin mode SNRM\_MODE = 4. + +Configuration parameter TXREFVNSF defines the transmitter-referred virtual noise scaling factor to be used together with the transmitter-referred virtual noise PSD in determining the SNR margin. + +The CO-MIB shall provide a TXREFVNSF parameter for downstream when SNRM\_MODE = 4. + +The values for the receiver-referred virtual noise PSD scaling factor shall be coded as 8-bit signed integers representing scaling factors from -64.0 dB (coded as -128) to +63.5 dB (coded as +127), in steps of 0.5 dB. + +The parameter in the downstream direction is TXREFVNSFds. + +The VTU-O shall combine the value of the configuration parameter TXREFVNSFds as in the CO-MIB with the value of the configuration parameter TXREFVNs as in the CO-MIB to a control parameter TXREFVNs as communicated to the VTU-R in O-SIGNATURE as follows: + +Control parameter TXREFVNs in $\text{dBm/Hz} = \min(\max((\text{configuration parameter TXREFVNs in dBm/Hz} + \text{configuration parameter TXREFVNSFds in dB}), -140 \text{ dBm/Hz}), -40 \text{ dBm/Hz})$ . + +#### 11.4.2.6 Re-Initialization policy parameters + +##### 11.4.2.6.1 Re-Initialization policy selection (RIPOLICY) + +The RIPOLICY configuration parameter (see clause 7.3.1.1.12 of [ITU-T G.997.1]) indicates which policy shall be applied to determine the triggers for re-initialization in a specific direction. The parameter in the downstream direction is RIPOLICYds, and the parameter in the upstream direction is RIPOLICYus. + +The control parameter $\text{RIPolicyds}_n$ shall have the same value as the configuration parameter RIPOLICYds in the CO-MIB for all downstream bearer channels. However, if configuration parameter RIPOLICYds=1 and the VTU-R indicates during ITU-T G.993.2 initialization in R-MSG 2 (see clause 12.3.5.2.2.1) that $\text{RIPolicyds}_n=1$ is not supported for a particular bearer channel, the VTU-O shall fall back to indicate $\text{RIPolicyds}_n=0$ in O-TPS (see clause 12.3.5.2.1.2) for that bearer channel. + +The control parameter $\text{RIPolicyus}_n$ shall have the same value as the configuration parameter RIPOLICYus in the CO-MIB for all upstream bearer channels. However, if $\text{RIPolicyus}_n=1$ is not supported by the VTU-O for a particular bearer channel, the VTU-O shall fall back to $\text{RIPolicyus}_n=0$ for that bearer channel. + +The valid values for RIPOLICY are 0 and 1. + +##### 11.4.2.6.2 REINIT\_TIME\_THRESHOLD + +Configuration parameter REINIT\_TIME\_THRESHOLD (see clause 7.3.1.1.13 of [ITU-T G.997.1]) defines the threshold for re-initialization based on SES, to be used by the VTU receiver when Re-Initialization Policy 1 is used (see clause 12.1.4). + +The downstream and upstream values of REINIT\_TIME\_THRESHOLD shall be configured in the CO-MIB. The parameter in the downstream direction is REINIT\_TIME\_THRESHOLDds, and the parameter in the upstream direction is REINIT\_TIME\_THRESHOLDus. + +The control parameter $\text{REINIT\_TIME\_THRESHOLDds}$ conveyed in O-MSG 1 shall have the same value as the configuration parameter REINIT\_TIME\_THRESHOLDds in the CO-MIB. The control parameter $\text{REINIT\_TIME\_THRESHOLDus}$ shall have the same value as the configuration parameter REINIT\_TIME\_THRESHOLDus in the CO-MIB. + +The value shall be coded as an unsigned integer representing the maximum number of SES. The valid range is from 5 to 31. + +#### 11.4.2.7 MAXDELAYOCTET-split (MDOSPLIT) + +The line configuration parameter MAXDELAYOCTET-split (MDOSPLIT) defines the percentage of the MAXDELAYOCTET allocated to the downstream direction. All of the remaining MAXDELAYOCTET shall be allocated for use in the upstream direction. + +MAXDELAYOCTET is the parameter "aggregate interleaver and de-interleaver delay", in octets, specified in Table 6-1 for the profile. A single MAXDELAYOCTET-split parameter is defined. The allocated number of octets shall be the total allocated to a given transmission direction for interleaving, and for all latency paths. + +Configuration of a split in percentage would result in fractional octets. Therefore, the following rounding rule shall apply ( $\lceil x \rceil$ denotes rounding to the higher integer): + +$$\text{MAXDELAYOCTET\_DS} = \lceil \text{MDOSPLIT} \times \text{MAXDELAYOCTET} \rceil$$ + +$$\text{MAXDELAYOCTET\_US} = \text{MAXDELAYOCTET} - \text{MAXDELAYOCTET\_DS}$$ + +The number of octets used in downstream direction (aggregated over both transceivers) shall be no higher than MAXDELAYOCTETS\_DS. The number of octets used in upstream direction (aggregated over both transceivers) shall be no higher than MAXDELAYOCTETS\_US. + +The sum of the max\_delay\_octet values specified in O-PMS (see clause 12.3.5.2.1.3) shall be limited to: + +$$\text{max\_delay\_octet}_{\text{DS},0} + \text{max\_delay\_octet}_{\text{DS},1} \leq \text{MAXDELAYOCTETS\_DS}$$ + +$$\text{max\_delay\_octet}_{\text{US},0} + \text{max\_delay\_octet}_{\text{US},1} \leq \text{MAXDELAYOCTETS\_US}$$ + +The above constraints depend only on the MAXDELAYOCTET-split parameter configured through the CO-MIB. The VTU-O shall not re-distribute the allocated max\_delay\_octets over downstream and upstream directions based on line conditions. As a result, some octets allocated to a given direction may remain unused. + +In case of dual latency (i.e., two bearer channels each in a different latency path), the VTU-O shall determine the max\_delay\_octet values allocated to each of the latency paths to optimize the data rate within the constraint given by the Rate Adaptation Ratio parameter defined in clause 7.3.2.1.4 of [ITU-T G.997.1]. + +MDOSPLIT shall be expressed as a percentage, with valid range from 5 percent to 95 percent inclusive, in steps of 1 percent. The value 0% is valid only if the maximum downstream interleaving delay is configured with the special value S1 (see clause 7.3.2.2 of [ITU-T G.997.1]). The value 100% is valid only if the maximum upstream interleaving delay is configured with the special value S1 (see clause 7.3.2.2 of [ITU-T G.997.1]). A special value shall indicate that the VTU-O is allowed to use a vendor discretionary algorithm to determine the max\_delay\_octet values specified in O-PMS. + +NOTE – A special value is introduced to ensure backward compatibility. + +#### 11.4.2.8 ATTNDR\_MAXDELAYOCTET-split (ATTNDR\_MDOSPLIT) + +The line configuration parameter ATTNDR\_MAXDELAYOCTET-split (ATTNDR\_MDOSPLIT) defines the percentage of the MAXDELAYOCTET allocated to the downstream direction to be used in the calculation of the ATTNDR. All of the remaining MAXDELAYOCTET shall be allocated for use in the upstream direction. + +MAXDELAYOCTET is the parameter "aggregate interleaver and de-interleaver delay", in octets, specified in Table 6-1 for the profile. A single ATTNDR\_MDOSPLIT parameter is defined. The allocated number of octets shall be the total allocated to a given transmission direction for interleaving, and for all latency paths. + +Configuration of a split in percentage would result in fractional octets. Therefore, the following rounding rule shall apply ( $\lceil x \rceil$ denotes rounding to the higher integer): + +$$\text{ATTNDR\_MAXDELAYOCTET\_DS} = \lceil \text{ATTNDR\_MDOSPLIT} \times \text{MAXDELAYOCTET} \rceil$$ + +$$\text{ATTNDR\_MAXDELAYOCTET\_US} = \text{MAXDELAYOCTET} - \text{ATTNDR\_MAXDELAYOCTET\_DS}$$ + +The number of octets used in downstream direction (aggregated over both transceivers) shall be no higher than ATTNDR\_MAXDELAYOCTET\_DS. The number of octets used in upstream direction (aggregated over both transceivers) shall be no higher than ATTNDR\_MAXDELAYOCTET\_US. + +If the ATTNDR calculation uses single latency mode, the ATTNDR\_max\_delay\_octet values shall be defined as: + +$$\text{ATTNDR\_max\_delay\_octet}_{\text{DS},0} = \text{ATTNDR\_MAXDELAYOCTET\_DS}$$ + +$$\text{ATTNDR\_max\_delay\_octet}_{\text{US},0} = \text{ATTNDR\_MAXDELAYOCTET\_US}$$ + +where the ATTNDR\_max\_delay\_octetDS,0 specifies the maximum of delay\_octetDS,0 that the VTU-R shall assume in the calculation of ATTNDR in downstream (see clause 12.3.5.2.1.3), and the ATTNDR\_max\_delay\_octetUS,0 specifies the maximum of delay\_octetUS,0 that the VTU-O shall assume in the calculation of ATTNDR in upstream. + +If the ATTNDR calculation uses single latency with ROC mode, the ATTNDR\_max\_delay\_octet values shall be defined as: + +$$\text{ATTNDR\_max\_delay\_octet}_{\text{DS},1} = \text{ATTNDR\_MAXDELAYOCTET\_DS} - \text{delay\_octet}_{\text{DS},0}$$ + +$$\text{ATTNDR\_max\_delay\_octet}_{\text{US},1} = \text{ATTNDR\_MAXDELAYOCTET\_US} - \text{delay\_octet}_{\text{US},0}$$ + +where the delay\_octetDS,0 and delay\_octetUS,0 values correspond to the actual configuration of the latency path #0 as applicable at the instant of ATTNDR calculation, + +and the ATTNDR\_max\_delay\_octetDS,1 specifies the maximum of delay\_octetDS,1 that the VTU-R shall assume in the calculation of ATTNDR in downstream (see clause 12.3.5.2.1.3), + +and the ATTNDR\_max\_delay\_octetUS,1 specifies the maximum of delay\_octetUS,1 that the VTU-O shall assume in the calculation of ATTNDR in upstream. + +The above constraints depend only on the ATTNDR\_MDOSPLIT parameter configured through the CO-MIB. + +ATTNDR\_MDOSPLIT shall be expressed as a percentage, with valid range from 5 per cent to 95 per cent inclusive, in steps of 1 per cent. The value 0% is valid only if the maximum downstream interleaving delay is configured with the special value S1 (see clause 7.3.2.2 of [ITU-T G.997.1]). The value 100% is valid only if the maximum upstream interleaving delay is configured with the special value S1 (see clause 7.3.2.2 of [ITU-T G.997.1]). A special value shall indicate that the VTU-O is allowed to use a vendor discretionary algorithm to determine the ATTNDR\_max\_delay\_octet values specified in O-PMS. + +## 11.5 Data gathering function + +The data gathering function stores records in a buffer, with each record entered in the buffer upon occurrence of a particular event type. These records may be used for diagnosing troubles and analysing functions. Different event types are defined; these are relevant to the operation of the line and are useful for determining what is functioning properly or what is not. Each event is recorded with a timestamp, the ID of the event type, and additional event data as defined for each event type. + +The VTU-O may optionally support the data gathering function. If supported, then the data gathering function shall comply with this clause, as applicable to the VTU-O. + +The VTU-R may optionally support the data gathering function. If supported, then the data gathering function shall comply with this clause, as applicable to the VTU-R. + +The data gathering function uses both the ITU-T G.993.2 transceiver functionality and the ITU-T G.997.1 functionality. Support of some ITU-T G.997.1 functionality is required to implement this clause. The data gathering function shall include a buffer of *logging\_depth* records. Each record shall include the following three fields: Event Timestamp, Event Type and Event Data. + +For each event type, a logging depth is defined as the minimum number of records of the event type that shall be kept in the buffer when deleting entries of this event type in case of buffer full condition. Per event type, the logging depth shall be configurable as a parameter derived from the configuration parameter *logging\_depth\_event\_percentagei* as follows: + +$$\text{logging\_depth\_event}_i = \lfloor (\text{logging\_depth\_event\_percentage}_i / 100\%) \times \text{logging\_depth} \rfloor$$ + +The sum over all event types of the configured *logging\_depth\_event\_percentagei* shall not exceed 100%, i.e., + +$$\sum_i \text{logging\_depth\_event\_percentage}_i \leq 100 \%$$ + +NOTE – If the sum of *logging\_depth\_eventi* is smaller than *logging\_depth*, then the remaining part of the buffer is used as a pool that can be used for any event type, within the buffer management rules defined in clause 11.5.2. + +The control parameter, *logging\_depth\_eventi*, is the minimum logging depth for event type *i* in number of 6-byte records, i.e., *logging\_depth\_eventi* is the minimum number of records of event type *i* that shall be kept in the event buffer of the VTU. This is logically the same as having a separate buffer for each event type, with each of these buffers able to store at least *logging\_depth\_eventi* records. + +The maximum depth of the entire event buffer is reported by the VTU as *logging\_depth*. + +The parameter *logging\_depth* is defined separately for the VTU-R and the VTU-O respectively as *logging\_depth\_R* and *logging\_depth\_O*. The reporting parameter *logging\_depth\_R* is the maximum depth of the buffer stored at the VTU-R and is reported in the CO-MIB as LOGGING\_DEPTH\_R (see clause 7.5.3.2 of [ITU-T G.997.1]). The reporting parameter *logging\_depth\_O* is the maximum depth of the buffer stored at the VTU-O and is reported in the CO-MIB as LOGGING\_DEPTH\_O (see clause 7.5.3.1 of [ITU-T G.997.1]). + +The control parameter *logging\_depth\_event\_percentagei* is defined separately for the VTU-R and the VTU-O respectively as *logging\_depth\_event\_percentage\_Ri* and *logging\_depth\_event\_percentage\_Oi*. The control parameter *logging\_depth\_event\_percentage\_Ri* shall have a value equal to the CO-MIB configuration parameter LOGGING\_DEPTH\_EVENT\_PERCENTAGE\_Ri (see clause 7.3.6.2 of [ITU-T G.997.1]). The control parameter *logging\_depth\_event\_percentage\_Oi* shall have a value equal to the CO-MIB configuration parameter LOGGING\_DEPTH\_EVENT\_PERCENTAGE\_Oi (see clause 7.3.6.1 of [ITU-T G.997.1]). + +At the VTU-O and VTU-R, the record length shall be fixed at 6 bytes (consisting of 4 bytes for the timestamp, 1 byte for the event type, and 1 byte for the event data). + +At the VTU-O, the timestamps as presented at the Q-interface (towards the MIB) shall be the number of seconds since Jan 1, 1900 as defined in [IETF RFC 5905] (NTP) coded in a 32-bit format. At the VTU-R, the timestamp as presented towards the U-interface (on the DSL) shall be the number of seconds since the last power cycle (mains power turned off/on) of the VTU-R, coded in a 32-bit format (with accuracy of time clock within $\pm 50$ ppm). The VTU-R timestamp shall be recorded in the CO-MIB in the same format as it presented toward the U-interface. + +A single record of each event type shall be stored once each second, unless no event of this type occurred during that second. In case an event (with a particular event ID, as per Table 11-43) has occurred multiple times during a one-second period, a single event shall be recorded with the + +timestamp for that one second period, and within this record the number of occurrences of the event may be reflected as part of the event data. + +The following subclauses identify which event types shall be supported by the VTU-O and/or VTU-R. The reporting of all supported event types is mandatory, i.e., there are no event types that are optionally supported. + +Clause 11.5.2 defines the buffer management rules. + +Clause 11.2.3.16 defines the mechanism for the VTU-O to retrieve over the eoc channel the data gathered in the VTU-R buffer. + +The logging depth that is applied for reporting the VTU-R buffer over the eoc channel is *logging\_depth\_reporting*. + +The VTU-O shall set *act\_logging\_depth\_reporting\_R* in the eoc configuration command message. The *act\_logging\_depth\_reporting\_R* shall be the minimum of: + +- The *logging\_depth\_R* (indicated by the VTU-R in the eoc configuration response message); +- The maximum depth of the buffer at the VTU-O that stores the records originated at the VTU-R as reported over the eoc channel; +- The CO-MIB configuration parameter LOGGING\_DEPTH\_REPORTING\_R (see clause 7.3.6.4 of [ITU-T G.997.1]). + +When sending a first configuration command, the VTU-O is not aware of the *logging\_depth\_R*. If the configuration command message indicates an *act\_logging\_depth\_reporting\_R* that is higher than *logging\_depth\_R*, then the VTU-R shall send a NACK response, and the VTU-O shall send a new configuration command to satisfy the above three conditions. + +The control parameter *act\_logging\_depth\_reporting\_R* is reported in the CO-MIB as ACT\_LOGGING\_DEPTH\_REPORTING\_R (see clause 7.5.3.4 of [ITU-T G.997.1]). + +The VTU-O shall set *act\_logging\_depth\_reporting\_O*. The *act\_logging\_depth\_reporting\_O* shall be the minimum of: + +- the *logging\_depth\_O*; +- the CO-MIB configuration parameter LOGGING\_DEPTH\_REPORTING\_O (see clause 7.3.6.3 of [ITU-T G.997.1]). + +The control parameter *act\_logging\_depth\_reporting\_O* is reported in the CO-MIB as ACT\_LOGGING\_DEPTH\_REPORTING\_O (see clause 7.5.3.3 of [ITU-T G.997.1]). + +If *act\_logging\_depth\_reporting\_R* is strictly less than *logging\_depth\_R*, then the VTU-R may store more than *act\_logging\_depth\_reporting\_R* records. In this case however, the VTU-R shall virtually reduce the number of stored records to no more than *act\_logging\_depth\_reporting\_R* records by applying the buffer management rules of clause 11.5.2 before reporting records over the eoc channel. For the data gathering functionality defined in this Recommendation, the term "VTU-R buffer" shall refer to the storage of up to *act\_logging\_depth\_reporting\_R* records. + +Upon a power cycle, the VTU-R: + +- shall reset the entire buffer by setting all records to be dummy records, where a dummy record is defined as a record which has all fields set to the value 0; and, +- shall set *Nnack* = 0; and, +- shall start data gathering with a reset of the timestamp to value 0, *act\_logging\_depth\_reporting\_R* = *logging\_depth\_R* and *logging\_depth\_percentage\_Ri* = 0 for all event types (i.e., the VTU-R buffer operates as a pure FIFO until the *logging\_depth\_reporting* and *logging\_depth\_event\_percentage\_Ri* are configured). + +A VTU-R supporting the data gathering functionality shall support the "previous-loss-of-power" (PLPR) flag. + +The records originated at the VTU-R (and reported to the VTU-O over the eoc channel) are contained in the CO-MIB parameter EVENT\_TRACE\_BUFFER\_R (see clause 7.5.3.6 of [ITU-T G.997.1]). The maximum number of records contained in this CO-MIB parameter is ACT\_LOGGING\_DEPTH\_REPORTING\_R (see clause 7.5.3.4 of [ITU-T G.997.1]). In the case that the number of records contained in this CO-MIB parameter is less than ACT\_LOGGING\_DEPTH\_REPORTING\_R, the remainder of the EVENT\_TRACE\_BUFFER\_R shall be set to all dummy records. + +The records originated at the VTU-O are contained in the CO-MIB parameter EVENT\_TRACE\_BUFFER\_O (see clause 7.5.3.5 of [ITU-T G.997.1]). The maximum number of records contained in this CO-MIB parameter is ACT\_LOGGING\_DEPTH\_REPORTING\_O (see clause 7.5.3.3 of [ITU-T G.997.1]). In the case that the number of records contained in this CO-MIB parameter is less than ACT\_LOGGING\_DEPTH\_REPORTING\_O, the remainder of the EVENT\_TRACE\_BUFFER\_O shall be set to all dummy records. + +### 11.5.1 Event types and event data + +Table 11-43 lists the event types defined for the data gathering function and the identifier that shall be used in the record to identify the event type. Table 11-43 also indicates whether the event type shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support" and O indicates "optional support"). + +**Table 11-43 – List of event types** + +| Event type | ID | VTU-O | VTU-R | Definition | +|-----------------------------------------------|--------------------------------------|-------|-------|----------------------| +| Dummy | 00 16 | M | M | See clause 11.5 | +| End of Showtime | 01 16 | M | M | See clause 11.5.1.1 | +| Previous End of Showtime | 02 16 | M | M | See clause 11.5.1.2 | +| Failed Init | 03 16 | M | M | See clause 11.5.1.3 | +| Successful Init | 04 16 | M | M | See clause 11.5.1.4 | +| Downstream Init Net Data Rate | 05 16 | M | M | See clause 11.5.1.5 | +| Upstream Init Net Data Rate | 06 16 | M | M | See clause 11.5.1.6 | +| Line Failure | 07 16 | M | M | See clause 11.5.1.7 | +| CRC-8 Anomalies | 08 16 | M | M | See clause 11.5.1.8 | +| OLR | 09 16 | M | M | See clause 11.5.1.9 | +| Bitswap | 0A 16 | M | M | See clause 11.5.1.10 | +| Downstream Net Data Rate After Successful SRA | 0B 16 | M | M | See clause 11.5.1.11 | +| Upstream Net Data Rate After Successful SRA | 0C 16 | M | M | See clause 11.5.1.12 | +| Downstream Net Data Rate After Successful SOS | 0D 16 | M | M | See clause 11.5.1.13 | +| Upstream Net Data Rate After Successful SOS | 0E 16 | M | M | See clause 11.5.1.14 | +| Defect | 0F 16 | M | M | See clause 11.5.1.15 | +| Retransmission event | 10 16 | M | M | See clause 11.5.1.16 | +| Reserved for use by ITU-T | 11 16 to 7F 16 | | | | + +**Table 11-43 – List of event types** + +| Event type | ID | VTU-O | VTU-R | Definition | +|----------------------------------|--------------------------------------|-------|-------|------------| +| Vendor-discretionary event types | 80 16 to FF 16 | | | | + +NOTE – Event types that are optional in this Recommendation are mandatory for the data gathering function only if the particular event type is supported by the VTU. + +### 11.5.1.1 Event type "End of Showtime" + +The event type "End of Showtime" shall occur when the VTU transitions from the SHOWTIME state to the SILENT state (see VTU-O state diagram in Figure 12-2 and VTU-R state diagram in Figure 12-3). The related event data shall identify the trigger issued at VTU-O or VTU-R for this transition. + +Table 11-44 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-44 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support" and RI1 indicates "mandatory only if *RIpolicyn*=1".) + +**Table 11-44 – Event data for event type "End of Showtime"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|-------------------------------------------------------------------------------------|--------------------------------------|-------|-------|----------------------------------------| +| Reserved for future use | 00 16 | | | | +| VTU-O host triggered re-initialization | 01 16 | M | M | L3_request and L3_grant in Figure 12-2 | +| VTU-R host triggered re-initialization | 02 16 | M | M | L3_request and L3_grant in Figure 12-3 | +| Persistent ne-LOS | 03 16 | M | M | See clause 12.1.4 | +| Persistent ne-LOF | 04 16 | M | M | See clause 12.1.4 | +| Contiguous ne-SES | 05 16 | M | M | See Table 12-4 (Note 2) | +| Persistent ne-LOM | 06 16 | M | M | See clause 12.1.4 | +| Persistent ne-TPS-TC out-of-sync | 07 16 | M | M | See clause 12.1.4 | +| MAX-SOS | 08 16 | M | M | See Table 12-3 | +| SOS rate low timeout | 09 16 | M | M | See Table 12-3 | +| EOC no response | 0A 16 | M | M | See Table 12-3 | +| Other vendor specific VTU-O or VTU-R near-end conditions declaring a high_BER event | 0B 16 | M | M | See Table 12-3 (Note 1) | +| Other vendor specific VTU-O or VTU-R far-end conditions declaring a high_BER event | 0C 16 | M | M | See Table 12-3 (Note 1) | +| High BER-hs event as defined for RIpolicyn =1 | 0D 16 | RI1 | RI1 | See Table 12-4 | +| Reserved for use by ITU-T | 0E 16 to FF 16 | | | | + +NOTE 1 – This event data ID shall only be used with *RIpolicyn* = 0. +NOTE 2 – Only if *RIpolicyn*=1, Table 12-4 defines this event data, otherwise it is vendor specific. + +### 11.5.1.2 Event type "Previous End of Showtime" + +The event type "Previous End of Showtime" shall occur when the VTU enters the SHOWTIME state (see VTU-O state diagram in Figure 12-2 and VTU-R state diagram in Figure 12-3) and the VTU-R has an initialization flag set to 1 (see clause 11.2.3.6). The purpose of this event is to indicate that the previous End of Showtime was due to a power cycle or host reinit at the VTU-R. This is important + +because the VTU-R's timestamp is reset when either of these actions occurs. The related event data shall represent the initialization flag set at the VTU-R (PLPR and PHPR as indicated by the VTU-R in the inventory commands and response, see clause 11.2.3.6). + +Table 11-45 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-45 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support" and NA indicates "not applicable"). + +**Table 11-45 – Event data for event type "Previous End of Showtime"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|-----------------------------------------------------------------------------------------------------|--------------------------------------|-------|-------|---------------------| +| Reserved for future use | 00 16 | | | | +| Previous-loss-of-power (PLPR) | 01 16 | NA | M | See clause 11.2.3.6 | +| Previous-host-reinit (PHRI) | 02 16 | NA | M | See clause 11.2.3.6 | +| Reserved for use by ITU-T | 03 16 to FF 16 | | | | +| NOTE – The timestamp for this event type is recorded immediately after the VTU-R is re-initialized. | | | | | + +### 11.5.1.3 Event type "Failed Init" + +The event type "Failed Init" shall occur when the VTU transitions from the INIT/TRAIN or INIT/HS state to the SILENT state (see VTU-O state diagram in Figure 12-2 and VTU-R state diagram in Figure 12-3). The related event data shall identify the last initialization phase the VTU-O or VTU-R entered before the initialization failed, e.g., channel discovery phase. + +Table 11-46 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-46 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). The octet specifying the event data for this event type is split in half, with the four MSB defining in which phase the initialization failed, and the four LSB specifying the initialization failure cause. The initialization failure cause shall be as defined in clause 7.5.1.6 of [ITU-T G.997.1] and shall be coded as a 4-bit unsigned integer (as shown in Table 11-45). + +**Table 11-46 – Event data for event type "Failed Init"** + +| Event data | Four MSB of ID | VTU-O | VTU-R | Definition | +|----------------------------------------|------------------------------------|-------|-------|---------------------------------------| +| Reserved for use by ITU-T | 0 16 | | | | +| ITU-T G.994.1 phase | 1 16 | M | M | See Figure 12-5 | +| Channel discovery phase | 2 16 | M | M | See Figure 12-5 | +| Training phase | 3 16 | M | M | See Figure 12-5 | +| Channel analysis and exchange phase | 4 16 | M | M | See Figure 12-5 | +| Reserved for future use | 5 16 to F 16 | | | | +| Event data | Four LSB of ID | VTU-O | VTU-R | Definition | +| Successful | 0 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | +| Configuration error | 1 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | +| Configuration not feasible on the line | 2 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | +| Communication problem | 3 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | + +**Table 11-46 – Event data for event type "Failed Init"** + +| Event data | Four MSB of ID | VTU-O | VTU-R | Definition | +|------------------------------------------------------------------------------------------------------------|------------------------------------|-------|-------|---------------------------------------| +| No peer xTU detected | 4 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | +| Any other or unknown initialization failure cause | 5 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | +| ITU-T G.998.4 retransmission mode was not selected while RTX_MODE = FORCED or with RTX_MODE = RTX_TESTMODE | 6 16 | M | M | See clause 7.5.1.6 of [ITU-T G.997.1] | +| Reserved for use by ITU-T | 7 16 to F 16 | | | | + +#### 11.5.1.4 Event type "Successful Init" + +The event type "Successful Init" shall occur when the VTU transitions from the INIT/TRAIN to the SHOWTIME state (see VTU-O state diagram in Figure 12-2 and VTU-R state diagram in Figure 12-3). The related event data shall be the number of the bit to be set in xTU Transmission System Enabling (XTSE) as defined in clause 7.3.1.1.1 of [ITU-T G.997.1] for the representation of the transmission system type. For example, event data = 3916 (57 decimal) is ITU-T G.993.2 Region A (North America) (Annex A). + +Table 11-47 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-47 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). + +**Table 11-47 – Event data for event type "Successful Init"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|-------------------------------------------------------------------------------------------|--------------------------------------|-------|-------|------------| +| Reserved for use by ITU-T | 00 16 | | | | +| Transmission system type | 01 16 to 40 16 | M | M | | +| Reserved for use by ITU-T | 41 16 to FF 16 | | | | +| NOTE – This event may be used to correlate the timestamps in the VTU-O and VTU-R buffers. | | | | | + +#### 11.5.1.5 Event type "Downstream Init Net Data Rate" + +The event type "Downstream Init Net Data Rate" shall occur when the VTU transitions from the INIT/TRAIN to the SHOWTIME state (see VTU-O state diagram in Figure 12-2 and VTU-R state diagram in Figure 12-3). The related event data shall identify the downstream net data rate applicable at the instant of entry into SHOWTIME. + +The Downstream Init Net Data Rate (NDR) shall be recorded in the event data as an index, represented as an unsigned single octet integer, which shall be the integer value closest to: + +$$63 \times \log_{10} \left( \frac{NDR}{0.2 \text{ Mbit/s}} \right) + 1, \text{ with } 1 \leq \text{index} \leq 253 \text{ for } 0.2 \text{ Mbit/s} \leq NDR \leq 2000 \text{ Mbit/s}.$$ + +If $NDR \leq 0.2 \text{ Mbit/s}$ , then the index shall be 0. If $NDR \geq 2000 \text{ Mbit/s}$ , then index shall be 254. The index value 255 shall be reserved. + +NOTE – This results in 3.7% granularity between recordable downstream net data rates. + +### 11.5.1.6 Event type "Upstream Init Net Data Rate" + +The event type "Upstream Init Net Data Rate" shall occur when the VTU transitions from the INIT/TRAIN to the SHOWTIME state (see VTU-O state diagram in Figure 12-2 and VTU-R state diagram in Figure 12-3). The related event data shall identify the upstream net data rate applicable at the instant of entry into SHOWTIME. + +The Upstream Init Net Data Rate shall be recorded in the event data in the same way as the Downstream Init Net Data Rate (see clause 11.5.1.5). + +### 11.5.1.7 Event type "Line Failure" + +The event type "Line Failure" shall occur every time instant when one or more near-end line failures occurs or terminates (see Table 7-10 of [ITU-T G.997.1]). These line failures may or may not result in a retrain. The related event data shall consist of a bitmap identifying each of the line failures, which can simultaneously record multiple types of line failures. The event data indicates whether each line failure initially occurs or terminates in the reported second. If there are no line failures occurring or terminating in this second, then this event is not recorded. + +Line failures are generated by the ITU-T G.997.1 functionality (see Figure 7-1 of [ITU-T G.997.1]). Therefore, the data gathering functionality gathers records from both the transceiver functionality and the ITU-T G.997.1 functionality. + +Table 11-48 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-48 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). + +**Table 11-48 – Event data for event type "Line Failure"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|----------------------------|-----------------|-------|-------|-----------------------------------------| +| LOS occurs | 0 0 x x x x 1 | M | M | See clause 7.1.1.1.1 of [ITU-T G.997.1] | +| LOS terminates | 0 0 x x x x 1 x | M | M | See clause 7.1.1.2.1 of [ITU-T G.997.1] | +| Loss of frame (LOF) occurs | 0 0 x x x 1 x x | M | M | See clause 7.1.1.1.2 of [ITU-T G.997.1] | +| LOF terminates | 0 0 x x 1 x x x | M | M | See clause 7.1.1.2.2 of [ITU-T G.997.1] | +| LPR occurs | 0 0 x 1 x x x x | M | M | See clause 7.1.1.1.3 of [ITU-T G.997.1] | +| LPR terminates | 0 0 1 x x x x x | M | M | See clause 7.1.1.2.3 of [ITU-T G.997.1] | + +NOTE – Event data denoted by "occurs" indicate the first occurrence of the event in a contiguous series. + +### 11.5.1.8 Event type "CRC-8 Anomalies" + +The event type "CRC-8 Anomaly" records one or more contiguous seconds with CRC-8 anomalies at the near-end (see clause 9.5.2.3). The event data shall consist of a bitmap identifying the start and end of the CRC-8 anomalies at the near-end, which can simultaneously record multiple CRC-8 starting and ending events. For this event type; event data "1 or more CRC-8s anomalies per second started" shall occur at the first occurrence of a contiguous series of seconds with one or more CRC-8 anomalies; event data "1 or more CRC-8s anomalies per second ended" shall occur in the second immediately following the last occurrence of a contiguous series of seconds with one or more CRC-8 anomalies; event data "18 or more normalized CRC-8s anomalies per second started" shall occur at the first occurrence of a contiguous series of seconds with 18 or more normalized CRC-8 anomalies; and event data "18 or more normalized CRC-8s anomalies per second ended" shall occur in the second immediately following the last occurrence of a contiguous series of seconds with 18 or more normalized CRC-8 anomalies. + +Table 11-49 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-49 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). + +**Table 11-49 – Event data for event type "CRC-8 Anomalies"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|----------------------------------------------------------|-----------------|-------|-------|--------------------| +| One or more CRC-8s anomalies per second starts | 0 0 0 0 x x 0 1 | M | M | See clause 9.5.2.3 | +| One or more CRC-8s anomalies per second ended | 0 0 0 0 x x 1 0 | M | M | See clause 9.5.2.3 | +| 18 or more normalized CRC-8s anomalies per second starts | 0 0 0 0 0 1 x x | M | M | See clause 9.5.2.3 | +| 18 or more normalized CRC-8s anomalies per second ended | 0 0 0 0 1 0 x x | M | M | See clause 9.5.2.3 | + +NOTE – One or more CRC-8 anomalies per second is one possible cause of an ES-L (see clause 7.2.1.1.2 of [ITU-T G.997.1]). 18 or more normalized CRC-8 anomalies per second is one possible cause of an SES-L (see clause 7.2.1.1.3 of [ITU-T G.997.1]). + +### 11.5.1.9 Event type "OLR" + +The event type "OLR" shall occur when an (sent or received) OLR command is deferred, rejected or positively acknowledged (i.e., successful) (see clause 13.1) and when no response to a sent OLR command is received within the specified time period (i.e., failed) (see Table 11-1). The related event data shall identify the result of the OLR procedure. Table 11-50 lists the event data, and the identifier that shall be used in the record to identify the event data. If there are one or more events with a given event data in this second, then the indicator bit corresponding to that event data is set to 1; the indicator bit is set to 0 otherwise. Multiple instances of different event data for this event that occur during the same second shall be recorded by setting multiple indicator bits to 1 as indicated in Table 11-50. + +Table 11-50 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). + +**Table 11-50 – Event data for event type "OLR"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|----------------------------------------------|-----------------|-------------------|-------------------|-----------------| +| Successful SRA downstream | x x x x x x x 1 | M | M | See clause 13.1 | +| Failed, deferred, or rejected SRA downstream | x x x x x x 1 x | M
(see Note 1) | M | See clause 13.1 | +| Successful SRA upstream | x x x x x 1 x x | M | M | See clause 13.1 | +| Failed, deferred, or rejected SRA upstream | x x x x 1 x x x | M | M
(see Note 1) | See clause 13.1 | +| Successful SOS downstream | x x x 1 x x x x | M | M | See clause 13.1 | +| Failed, deferred, or rejected SOS downstream | x x 1 x x x x x | M
(see Note 1) | M | See clause 13.1 | +| Successful SOS upstream | x 1 x x x x x x | M | M | See clause 13.1 | + +**Table 11-50 – Event data for event type "OLR"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|-------|-------------------|-----------------| +| Failed, deferred, or rejected SOS upstream | 1 x x x x x x | M | M
(see Note 1) | See clause 13.1 | +| NOTE 1 – A failed event would not be recorded in this case. | | | | | +| NOTE 2 – Event types that are optional in this Recommendation are mandatory for the data gathering function only if the particular event type is supported by the VTU. | | | | | + +#### 11.5.1.10 Event type "Bitswap" + +The event type "Bitswap" shall occur when a bitswap command is deferred, rejected or positively acknowledged (i.e., successful), (see clause 13.1) and when no response to a sent bit swapping command is received within the specified time period (i.e., failed) (see Table 11-1). The related event data as per Table 11-51 shall identify the result of the bit swapping procedure. + +If a particular bitswap event data occurs at least once, then the bit corresponding to the Bitswap event data in Table 11-51 shall be set to "1". If a particular bitswap event data did not occur, then the bit corresponding to the Bitswap event data in Table 11-51 shall be set to "0". The two highest MSB of the ID shall indicate the number of occurrences of this event during this second, i.e., one event, two events, and more than two events. Multiple instances of this event that occur in the same second shall be recorded simultaneously in a single record using the first two bits of the event data ID to record the total number of Bitswap events. Table 11-51 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-51 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). + +**Table 11-51 – Event data for event type "Bitswap"** + +| Event data | Two MSB of ID | VTU-O | VTU-R | Definition | +|-------------------------------------------------------------|---------------|--------------|--------------|----------------------------------| +| Number of Bitswap events | 0 1 | M | M | 1 = Number of Bitswap events | +| | 1 0 | M | M | 2 = Number of Bitswap events | +| | 1 1 | M | M | 3 = More than two Bitswap events | +| | Six LSB of ID | VTU-O | VTU-R | Definition | +| Event data | | | | | +| Successful bitswap downstream | x x x x x 1 | M | M | See clause 13.1 | +| Failed, deferred or rejected bitswap downstream | x x x x 1 x | M (see Note) | M | See clause 13.1 | +| Successful bitswap upstream | x x x 1 x x | M | M | See clause 13.1 | +| Failed, deferred or rejected bitswap upstream | x x 1 x x x | M | M (see Note) | See clause 13.1 | +| NOTE – A failed bitswap would not be recorded in this case. | | | | | + +#### 11.5.1.11 Event type "Downstream Net Data Rate after Successful SRA" + +The event type "Downstream Net Data Rate after Successful SRA" shall occur when a downstream SRA request is positively acknowledged (i.e., successful). The related event data shall identify the downstream net data rate applicable at the completion of the SRA procedure. + +The Downstream Net Data Rate after Successful SRA shall be recorded in the event data in the same way as the Downstream Init Net Data Rate (see clause 11.5.1.5). + +#### **11.5.1.12 Event type "Upstream Net Data Rate after Successful SRA"** + +The event type "Upstream Net Data Rate after Successful SRA" shall occur when an upstream SRA request is positively acknowledged (i.e., successful). The related event data shall identify the upstream net data rate applicable at the completion of the SRA procedure. + +The Upstream Net Data Rate after Successful SRA shall be recorded in the event data in the same way as the Downstream Init Net Data Rate (see clause 11.5.1.5). + +#### **11.5.1.13 Event type "Downstream Net Data Rate after Successful SOS"** + +The event type "Downstream Net Data Rate after Successful SOS" shall occur when a downstream SOS request is positively acknowledged (i.e., successful). The related event data shall identify the downstream net data rate applicable at the completion of the SOS procedure. + +The Downstream Net Data Rate after Successful SOS shall be recorded in the event data in the same way as the Downstream Init Net Data Rate (see clause 11.5.1.5). + +#### **11.5.1.14 Event type "Upstream Net Data Rate after Successful SOS"** + +The event type "Upstream Net Data Rate after Successful SOS" shall occur when an upstream SOS request is positively acknowledged. The related event data shall identify the upstream net data rate applicable at the completion of the SOS procedure. + +The Upstream Net Data Rate after Successful SOS shall be recorded in the event data in the same way as the Downstream Init Net Data Rate (see clause 11.5.1.5). + +#### **11.5.1.15 Event type "Defect"** + +If a *los*, *lom*, or *sef* defect (see clauses 11.3.1.3 and 11.3.1.4) occurs during any part of a second, then that second is considered to be a *los* defected second, a *lom* defected second, or a *sef* defected second, respectively. The event type "Defect" shall occur each second when any type of defected second starts or ended. A type of defected second shall be recorded as "starts" when that type of defected second occurs in the current second but did not occur in the previous second. A type of defected second shall be recorded as having "ended" when that type of defected second occurred in the previous second but does not occur in the current second. A particular type of defected second (*los* defected second, *lom* defected second, or *sef* defected second) cannot both start and stop in the same second. In order to gather multiple types of defected second events in one record, the event data shall consist of a bitmap identifying the start and end each of each type of defected second. + +Table 11-52 lists the event data and the identifier that shall be used in the event record to identify the event data. Table 11-52 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support" and "NA" indicates "not applicable"). + +**Table 11-52 – Event data for event type "Defect"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|--------------------------|-----------------|-------|-------|---------------------| +| los second starts | x x x x x 0 1 | M | M | See clause 11.3.1.3 | +| los second ended | x x x x x 1 0 | M | M | See clause 11.3.1.3 | +| lom second starts | x x x x 0 1 x x | M | M | See clause 11.3.1.3 | +| lom second ended | x x x x 1 0 x x | M | M | See clause 11.3.1.3 | +| sef second starts | x x 0 1 x x x x | M | M | See clause 11.3.1.3 | +| sef second ended | x x 1 0 x x x x | M | M | See clause 11.3.1.3 | + +#### 11.5.1.16 Event type "Retransmission Event" + +The event type "Retransmission Event" shall occur when the VTU operates in ITU-T G.998.4 (retransmission) mode and one of the retransmission events (see Table 11-53) occurs. The related event data shall identify the retransmission event that occurred. + +Table 11-53 lists the event data, and the identifier that shall be used in the record to identify the event data. Table 11-53 also indicates whether the event data shall be supported by the VTU-O and/or VTU-R (M indicates "mandatory support"). + +**Table 11-53 – Event data for event type "Retransmission Event"** + +| Event data | ID | VTU-O | VTU-R | Definition | +|---------------------------|--------------------------------------|-------|-------|--------------------------------------| +| Reserved for future use | 00 16 | | | | +| leftfr defect | 01 16 | M | M | See clause 11.3.3 of [ITU-T G.998.4] | +| Reserved for use by ITU-T | 02 16 to FF 16 | | | | + +NOTE – The *leftfr* defect is recorded only for upstream at the VTU-O, and it is reported only for downstream at the VTU-R. This is because the *leftfr* defect is near-end only. + +#### 11.5.2 Buffer management rules + +In order to obtain a fair mixing of event types in the buffer, while guaranteeing that the oldest entries per event type are removed first, the following buffer management rules shall apply: + +- The sum of the configured logging depths, *logging\_depth\_eventi*, over all event types shall be smaller than or equal to the number of storable records in the buffer, *logging\_depth*; +- When the buffer is not yet full, a new entry can be added without constraints; +- When the buffer is full, before adding a new entry, one entry shall be removed. The entry that shall be removed is the oldest entry out of all event types which are already above their configured logging depths or which would get above their configured logging depths if the new entry was to be added without a removal; + +NOTE – The third rule is described as a "remove before add". It can also be rephrased as "remove after add" as follows: "when the buffer is full, the new entry is added to a spare location. The entry that shall be removed is the oldest entry out of all event types which are above their configured logging depths." + +These buffer management rules are illustrated in Figure 11-6. + +![Figure 11-6: Illustration of the buffer management rules. A timeline shows seven buffer states over time, with events B1, B2, C2, A4, B3, and C3 occurring. Red 'X' marks indicate deletions. A text box specifies FIFO size: 6 records and configured logging depths: Event Type A: 2, Event Type B: 1, Event Type C: 2.](ca7e6c1823b101e869d4f177c147bea6_img.jpg) + +newest 6 + +5 + +4 + +3 + +2 + +oldest 1 + +Event B1 happens   Event B2 happens   Event C2 happens   Event A4 happens   Event B3 happens   Event C3 happens       **TIME LINE** + +| | | | | | | | +|---------|---------|----|----|----|----|----| +| C1 | B1 | B2 | C2 | A4 | B3 | C3 | +| A3 | C1 | B1 | B2 | C2 | A4 | B3 | +| A2 | A3 | C1 | B1 | B2 | C2 | A4 | +| A1 | A2 | A3 | C1 | B1 | B2 | C2 | +| | A1 | A2 | A3 | C1 | C1 | B2 | +| | | A1 | A2 | A3 | A3 | A3 | + +FIFO size: **6 records** + +Configured logging depth: +Event Type A: 2 +Event Type B: 1 +Event Type C: 2 + +A1 deleted, as oldest one of types A and B which are both above their logging depth. + +A2 deleted, as oldest entry of types A and B, where B is above its logging depth and A is getting above its logging depth. + +B1 deleted, as oldest one of type B which is only type that is above its logging depth. + +C1 deleted, as oldest entry of types B and C, where B is above its logging depth and C is getting above its logging depth. + +Figure 11-6: Illustration of the buffer management rules. A timeline shows seven buffer states over time, with events B1, B2, C2, A4, B3, and C3 occurring. Red 'X' marks indicate deletions. A text box specifies FIFO size: 6 records and configured logging depths: Event Type A: 2, Event Type B: 1, Event Type C: 2. + +**Figure 11-6 – Illustration of the buffer management rules** + +## 12 Link activation methods and procedures + +### 12.1 Overview + +#### 12.1.1 Link states and link state diagram + +The VDSL2 link states and activation/deactivation procedures diagram is illustrated in Figure 12-1. + +![Figure 12-1: VDSL2 link states and link state diagram. A state transition diagram showing two link states (L0 and L3) and three procedures (Loop Diagnostic mode, Initialization, Deactivation) with various transitions between them.](4df70569f4cc27db5625fc75bdff68cf_img.jpg) + +``` + +graph TD + L3([L3 link state]) + L0([L0 link state]) + Loop[Loop Diagnostic mode procedures] + Init[Initialization procedures] + Deact[Deactivation procedure] + + L3 -- Activation --> Init + Init -- Pass --> L0 + Init -- Fail --> L3 + Init -- Grant --> Deact + Deact -- Reject --> L0 + Deact -- "Power loss, persistent link failure" --> L0 + L0 -- "L3 request" --> Deact + L3 -- Pass/Fail --> Loop + Loop -- Pass/Fail --> L3 + +``` + +G.993.2\_F12-1 + +Figure 12-1: VDSL2 link states and link state diagram. A state transition diagram showing two link states (L0 and L3) and three procedures (Loop Diagnostic mode, Initialization, Deactivation) with various transitions between them. + +**Figure 12-1 – VDSL2 link states and link state diagram** + +Figure 12-1 has two link states (L0 and L3), and also contains the procedures that allow the link to change from one link state to another. The link states are shown in rounded boxes, whilst the procedures are shown as rectangular boxes. + +L3 is the link state where the VTU is provisioned through a management interface for the service desired by the operator. In this link state, both the VTU-O and VTU-R do not transmit any signal. + +L0 is the link state achieved after the initialization procedure has completed successfully by both VTUs. In this link state, the link shall transport user information with standard performance characteristics according to the CO-MIB configuration. + +### 12.1.2 Transceiver states and transceiver state diagram + +State diagrams are given in Figure 12-2 for the VTU-O, and in Figure 12-3 for the VTU-R. States are indicated by ovals, with the name of the state given within the oval. The states are defined in Table 12-1 for the VTU-O and in Table 12-2 for the VTU-R. Transitions between states are indicated by arrows, with the event causing the transition listed next to the arrow. All states are mandatory. + +A variety of "host controller" commands (events preceded by "c:" and "r:") are shown as non-mandatory in either state diagram to provide example events and transitions between states. The way in which these events are implemented is left to the vendor since many options are possible. + +In the state diagram for the VTU-O, a C-IDLE state would be desired to guarantee a quiet mode, which may be useful to allow certain tests (e.g., MLT), or to discontinue service. + +In the state diagram for the VTU-R, a self-test function is desirable, but it may be a vendor/customer option to define when self-test occurs (e.g., always at power-up or only under VTU-O control), and which transition to take after successfully completing self-test (e.g., enter R-IDLE, or enter R-SILENT). + +IDLE is the state where the VTU is provisioned through a management interface for the service desired by the operator. In this state, the VTU does not transmit any signal. A VTU that receives a higher layer signal to activate (c: L0\_request for VTU-O or r: L0\_request for VTU-R) shall use the initialization procedure defined in clause 12.3 to transition the link from the L3 to the L0 state. A VTU that detects the signals of the initialization procedure at the U reference point, if enabled, shall respond by using the initialization procedure. If disabled, the VTU shall remain in the IDLE state. + +The link transitions to the L0 state once the initialization procedure has completed successfully and both VTUs are in the SHOWTIME state. A VTU-O shall return to the O-SILENT state upon a guided power management (c: L3\_request, see clause 11.2.3.9), or upon a re-initialization triggered by Re-Initialization Policy (see clause 12.1.4). A VTU-R shall return to the R-SILENT state upon a guided power management (r: L3\_request, see clause 11.2.3.9), or upon a re-initialization triggered by Re-Initialization Policy (see clause 12.1.4). With the former, a VTU-R shall set AUTO\_init=OFF to disable autonomous proceeding to the R-INIT/HS state. With the latter, a VTU-R shall set AUTO\_init=ON to enable autonomous proceeding to the R-INIT/HS state. + +The receiving VTU shall transition state upon Persistent LOS and/or LOF failure (see clause 12.1.4). This implies that if no high\_BER-hs or high\_BER-fs events cause the receiving VTU to transition state earlier, then the persistency allows the transmitting VTU to detect the LOS or LOF failure condition through the indicator bits, before the receiving VTU transitions state (i.e., removes the Showtime signal from the line). + +NOTE – High\_BER-fs event relates to fast start-up, which is for further study (see clause 12.5). + +The receiving VTU shall also transition state upon a high\_BER event (see clause 12.1.4). This event relates to near-end and/or far-end performance primitives and performance counters for which thresholds may be configured through the CO-MIB as to declare a high\_BER event upon threshold crossing. + +If the VTU-O transitions from O-SHOWTIME to O-SILENT, then the VTU-R shall detect a Persistent LOS Failure, shall transition to R-SILENT followed by R-INIT/HS and shall transmit R-TONES-REQ within a maximum of 6 s after the VTU-O transitioning to O-SILENT. + +If the VTU-R transitions from R-SHOWTIME to R-SILENT, then the VTU-O shall detect a Persistent LOS Failure, shall transition to O-SILENT, either followed by waiting to receive R-TONES-REQ (VTU-R initiated HS) or followed by O-INIT/HS (VTU-O initiated HS). + +![State diagram for the VTU-O showing transitions between states like O-IDLE, O-SILENT, O-INIT/HS, O-INIT/TRAIN, O-SHOWTIME, O-SELFTEST, O-UNIT-FAIL, and O-INIT/DIAG.](6fd13a25b57a43ec4327cca60c294973_img.jpg) + +The diagram illustrates the operational states and transitions of a VTU-O. + - **Power on** leads to **O-SELFTEST**. + - **O-SELFTEST** transitions to **O-IDLE** on 'Pass' or **O-UNIT-FAIL** on 'Fail'. + - **O-IDLE** (ignore VTU-R) transitions to **O-SILENT** on 'o:\_L0\_request'. + - **O-SILENT** (monitor VTU-R) transitions to **O-INIT/HS** on 'o:\_L0\_request or r-tones-req'. + - **O-INIT/HS** (ITU-T G.994.1 session) transitions to **O-INIT/TRAIN** on 'Pass with mode selected', to **O-INIT/DIAG** on 'Diagnostics', or back to **O-SILENT** on 'Fail' or 'Pass with silent or no mode selected'. + - **O-INIT/TRAIN** (training) transitions to **O-SHOWTIME** on 'Pass' or back to **O-SILENT** on 'Fail'. + - **O-SHOWTIME** can transition back to **O-SILENT** due to 'Re-initialization triggered by Re-initialization policy' or 'high\_BER-fs'. It also has self-transitions for L3 requests/rejects and a transition to **O-SILENT** for L3 grant conditions. + - **O-INIT/DIAG** (loop diagnostics) transitions back to **O-SILENT** on 'Pass or fail'. + - A legend indicates that an oval denotes a state and a curved arrow denotes a transition under a specific condition. + +State diagram for the VTU-O showing transitions between states like O-IDLE, O-SILENT, O-INIT/HS, O-INIT/TRAIN, O-SHOWTIME, O-SELFTEST, O-UNIT-FAIL, and O-INIT/DIAG. + +**Figure 12-2 – State diagram for the VTU-O** + +Rec. ITU-T G.993.2 (02/2019) 185 + +![State diagram for the VTU-R showing states R-IDLE, R-SILENT, R-INIT/HS, R-INIT/TRAIN, R-SHOWTIME, R-SELFTEST, and R-UNIT-FAIL with transitions between them based on various conditions like r:_idle_ignore, r:_L0_request, auto_init, Pass, Fail, Diagnostics, high_BER-fs, and L3 requests/grants.](bd0fe87fe6e236bc4778830b4f26d9e2_img.jpg) + +``` + +stateDiagram-v2 + [*] --> R-SELFTEST : Power on + R-SELFTEST --> R-IDLE : r:_selftest, Pass and auto_init = OFF + R-SELFTEST --> R-SILENT : Pass and auto_init = ON + R-SELFTEST --> R-UNIT-FAIL : Fail + R-IDLE --> R-SILENT : r:_L0_request, auto_init = ON + R-IDLE --> [*] : r:_idle_ignore + R-SILENT --> R-INIT/HS : auto_init = ON or r:_L0_request or c-tones + R-SILENT --> R-INIT/TRAIN : Fail + R-SILENT --> [*] : Pass with silent or no mode selected + R-INIT/HS --> R-INIT/DIAG : Diagnostics + R-INIT/HS --> R-INIT/TRAIN : Pass with mode selected + R-INIT/HS --> R-SILENT : Fail + R-INIT/DIAG --> R-INIT/HS : Pass or fail + R-INIT/DIAG --> R-SILENT : auto_init = OFF + R-INIT/TRAIN --> R-SHOWTIME : Pass + R-INIT/TRAIN --> R-SILENT : high_BER-fs + R-SHOWTIME --> R-INIT/TRAIN : r:_L3_request and o:_L3_reject, o:_L3_request and r:_L3_reject + R-SHOWTIME --> R-INIT/HS : Re-initialization triggered by Re-initialization policy + R-SHOWTIME --> R-SILENT : auto_init = ON + R-SHOWTIME --> R-INIT/DIAG : r:_L3_request and o:_L3_grant, o:_L3_request and r:_L3_grant + +``` + +State diagram for the VTU-R showing states R-IDLE, R-SILENT, R-INIT/HS, R-INIT/TRAIN, R-SHOWTIME, R-SELFTEST, and R-UNIT-FAIL with transitions between them based on various conditions like r:\_idle\_ignore, r:\_L0\_request, auto\_init, Pass, Fail, Diagnostics, high\_BER-fs, and L3 requests/grants. + +G.993.2(15)\_F12-3 + +![Legend for the state diagram: an oval denotes a state, a rectangle denotes an action, and a curved arrow with condition 'c' denotes a transition under condition c.](9a8f8276c7199f1dd9f3754cf60555c6_img.jpg) + +○ denotes a state + □ denotes an action + ⌒c denotes a transition under condition c + +Legend for the state diagram: an oval denotes a state, a rectangle denotes an action, and a curved arrow with condition 'c' denotes a transition under condition c. + +Figure 12-3 – State diagram for the VTU-R + +**Table 12-1 – VTU-O state definitions** + +| State name | Description | +|-----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| O-SELFTEST
(mandatory) |
  • Temporary state entered after power-up in which the VTU performs a self-test;
  • Transmitter off (QUIET at U-O interface);
  • Receiver off (no response to R-TONES-REQ signal);
  • No response to host control channel;
  • If self-test pass then transition to O-IDLE;
  • If self-test fail then transition to O-UNIT-FAIL.
| +| O-UNIT-FAIL
(mandatory) |
  • Steady state entered after an unsuccessful VTU self-test;
  • Transmitter off (QUIET at U-O interface);
  • Receiver off (no response to R-TONES-REQ signal);
  • Monitor host control channel if possible (allows the host controller to retrieve self-test results).
| +| O-IDLE
(mandatory) |
  • Steady state entered after successful self-test;
  • Transmitter off (QUIET at U-O interface);
  • Receiver off (no response to R-TONES-REQ signal);
  • Monitor host control channel.
| +| O-SILENT
(mandatory) |
  • Steady state defined in ITU-T G.994.1, entered upon host controller command;
  • Transmitter off (QUIET at U-O interface);
  • Receiver on (monitor for R-TONES-REQ signal, if detected, transition to O-INIT/HS state);
  • Monitor host control channel.
| +| O-INIT/HS
(mandatory) |
  • Temporary state entered to perform ITU-T G.994.1 phase of initialization;
  • Transmitter on (start with transmitting C-TONES signal);
  • Receiver on (start with monitoring for R-SILENT0 signal);
  • Monitor host control channel;
  • If silent period or no mode selected then transition to O-SILENT1;
  • If loop diagnostics mode then transition to O-INIT/DIAG;
  • If operating mode selected then transition to O-INIT/TRAIN.
| +| O-INIT/TRAIN
(mandatory) |
  • Temporary state entered to perform other phases of initialization;
  • Transmitter on (start with O-P-QUIET1);
  • Receiver on (start with monitoring for R-P-QUIET1);
  • If init pass then transition to O-SHOWTIME;
  • If init fail then transition to O-SILENT;
  • Monitor host control channel.
| +| O-INIT/DIAG
(mandatory) |
  • Temporary state entered to perform other phases of initialization in loop diagnostics mode;
  • Transmitter on (start with O-P-QUIET1);
  • Receiver on (start with monitoring for R-P-QUIET1);
  • Transition to O-SILENT;
  • Monitor host control channel.
| +| O-SHOWTIME
(mandatory) |
  • Steady state entered to perform bit pump functions (frame bearers active);
  • On-line reconfigurations occur within this state;
  • Upon conditions satisfying the Re-Initialization Policy (RIpolicyn) then transition to O-SILENT;
  • If link transition to L3 state is granted, then transition to O-SILENT;
  • Monitor host control channel.
| + +**Table 12-2 – VTU-R state definitions** + +| State name | Description | +|-----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| R-SELFTEST
(mandatory) |
  • Temporary state entered after power-up in which the VTU performs a self-test;
  • Transmitter off (QUIET at U-R interface);
  • Receiver off (no response to C-TONES signal);
  • No response to host control channel;
  • If self-test pass then transition to R-IDLE if VTU is under host control or transition to R-SILENT if VTU is in automatic training mode;
  • If self-test fail then transition to R-UNIT-FAIL.
| +| R-UNIT-FAIL
(mandatory) |
  • Steady state entered after an unsuccessful VTU self-test;
  • Transmitter off (QUIET at U-R interface);
  • Receiver off (no response to C-TONES signal);
  • Monitor host control channel if possible (allows the host controller to retrieve self-test results).
| +| R-IDLE
(mandatory) |
  • Steady state entered after successful self-test if VTU is under host control;
  • Transmitter off (QUIET at U-R interface);
  • Receiver off (no response to C-TONES signal);
  • Monitor host control channel.
| +| R-SILENT
(mandatory) |
  • Temporary state defined in[ITU-T G.994.1] entered after self-test pass if VTU is in automatic training mode or with host controller command;
  • Transmitter off (transmit R-SILENT0 signal);
  • Receiver on (monitor for C-TONES signal, if detected, transition to R-INIT/HS state);
  • Automatic training: immediate transition to R-INIT/HS (unless delayed for silent period or in orderly shutdown condition);
  • Monitor host control channel.
| +| R-INIT/HS
(mandatory) |
  • Temporary state entered to perform ITU-T G.994.1 phase of initialization;
  • Transmitter on (start with transmitting R-TONES-REQ signal);
  • Receiver on (start with monitoring for C-TONES signal);
  • Monitor host control channel;
  • If silent period or no mode selected then transition to R-SILENT;
  • If loop diagnostics mode then transition to R-INIT/DIAG;
  • If operating mode selected then transition to R-INIT/TRAIN.
| +| R-INIT/TRAIN
(mandatory) |
  • Temporary state entered to perform other phases of initialization;
  • Transmitter on (start with R-P-QUIET1 signal);
  • Receiver on (start with monitoring for C-P-QUIET1 signal);
  • If init pass then transition to R-SHOWTIME;
  • If init fail then transition to R-SILENT;
  • Monitor host control channel.
| +| R-INIT/DIAG
(mandatory) |
  • Temporary state entered to perform other phases of initialization in loop diagnostics mode;
  • Transmitter on (start with R-P-QUIET1);
  • Receiver on (start with monitoring for C-P-QUIET1);
  • Transition to R-SILENT;
  • Monitor host control channel.
| + +**Table 12-2 – VTU-R state definitions** + +| State name | Description | +|---------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| R-SHOWTIME
(mandatory) |
  • • Steady state entered to perform bit pump functions (frame bearers active);
  • • On-line reconfigurations occur within this state;
  • • Upon conditions satisfying the Re-Initialization Policy (RIpolicyn) then transition to R-SILENT;
  • • If link transition to L3 state is granted, then transition to R-SILENT;
  • • Monitor host control channel.
| + +### 12.1.3 Initialization procedures + +During the ITU-T G.994.1 handshake phase of the initialization procedure, the VTUs exchange capability lists and agree on a common mode for training and operation using the ITU-T G.994.1 protocol. A successful completion of the ITU-T G.994.1 handshake phase will lead to either the channel discovery phase of initialization or the loop diagnostic mode (depending on which one is selected). Failure of the ITU-T G.994.1 handshake phase leads the VTU back to the SILENT state and leads the link back to the L3 state. The handshake procedure is described in clause 12.3.2 and [ITU-T G.994.1]. + +During the channel discovery, training, and channel analysis and exchange phases of initialization, the VTUs train their respective transceivers after identifying the common mode of operation. During these phases, the transceivers identify channel conditions, exchange parameters for Showtime operation, etc. After successful completion of the initialization procedure, the transceivers transition to the SHOWTIME state (Showtime). Upon unsuccessful completion of the initialization procedure, the VTUs return to the SILENT state and the link returns to the L3 state. The initialization phases are described in clauses 12.3.3 through 12.3.5. + +### 12.1.4 Deactivation, power loss, persistent link failure and high\_BER events + +The deactivation procedure allows an orderly shutdown of the link. The VTUs shall follow the procedures described in clause 11.2.3.9 to transition the link from the L0 state to the L3 state. + +The link is in the L3 state, after both VTU-O and VTU-R have transitioned from the SHOWTIME state to the SILENT state. + +Two policies are defined for the VTU to trigger a transition from the SHOWTIME state to the SILENT state. The selection of the policy is controlled via the parameter "Re-Initialization Policy" (*RIpolicyn*). + +In the first policy (*RIpolicyn*=0) (mandatory), a VTU shall transition from the SHOWTIME state to the SILENT state in the case of: + +1. loss of receive power (power loss); or +2. persistent link failure; or +3. upon a high\_BER-hs event as defined below for *RIpolicyn*=0. + +The VTU shall declare a power loss when a persistent LOS failure is declared. Persistent LOS failure is declared after $2.5 \pm 0.5$ s of near-end LOS failure with the *los* (see clause 11.3.1.3) still present. An LOS failure is declared after $2.5 \pm 0.5$ s of contiguous *los*, or, if *los* is present when the criteria for LOF failure declaration have been met (see LOF Failure definition below). An LOS failure is cleared after $10 \pm 0.5$ s of no *los*. + +The VTU shall declare a persistent link failure when a persistent LOF failure is declared. A persistent LOF failure is declared after $2.5 \pm 0.5$ s of near-end LOF failure with the *sef* (see clause 11.3.1.3) still present. An LOF failure is declared after $2.5 \pm 0.5$ s of contiguous near-end *sef*, except when a *los* or + +LOS failure is present (see LOS failure definition above). An LOF failure is cleared when LOS failure is declared, or after $10 \pm 0.5$ s of no *sef*. + +The high\_BER-hs event in *RIpolicyn=0* shall be declared whenever any of the parameters listed in Table 12-3 exceeds the listed threshold. Other conditions are vendor-specific and are (but are not required to be) related to near-end and/or far-end performance primitives. As an example, the VTU may also declare a high\_BER event after 30 s of persistent near-end or far-end *lom* defect. The VTU should trade-off the persistency in the high\_BER events to, on the one hand, quickly recover data integrity, but on the other hand, not to unnecessarily interrupt data transmission. This trade-off may be enhanced if the VTU is able to detect and quantify instantaneous changes in line conditions. + +**Table 12-3 – Conditions for declaring a high\_BER-hs event in *RIpolicyn=0*** + +| Parameter | Threshold | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------| +| Number of successful SOS procedures performed within a 120-second interval | MAX-SOS threshold configured in CO-MIB | +| Number of seconds the actual net data rate ( net_actn ) is below the minimum net data rate ( net_minn ) for any bearer channel after a successful SOS procedure | 20 seconds | +| Duration of time interval with consecutive eoc message time-outs without a single successful eoc command/response exchange | Vendor discretionary | +| NOTE – Other conditions declaring a high_BER event are vendor specific. | | + +In determining the number of successful SOS procedures performed within a 120-second interval, the 120-second measurement interval shall be started at the first successful SOS procedure after getting into Showtime and re-started at the first successful SOS procedure occurring after a previous 120-second period interval has expired with the number of successful SOS procedures being less than MAX-SOS. The 120 second measurement intervals shall be sequential periods, not a sliding window. The SOS procedure shall be considered as successful when the VTU initiating the SOS receives the SyncFlag in response (regardless whether the SyncFlag was received after a single or multiple SOS requests). + +In the second policy (*RIpolicyn=1*) (optional), a VTU shall transition from the SHOWTIME state to the SILENT state in the case of: + +- 1) loss of receive power (power loss); or +- 2) persistent link failure; or +- 3) persistent near-end loss of margin failure; or +- 4) persistent TPS-TC out-of-sync failure; or +- 5) upon a high\_BER-hs event as defined below for *RIpolicyn=1*. + +The VTU shall declare a power loss identical to Re-Initialization Policy 0. + +The VTU shall declare a persistent link failure identical to Re-Initialization Policy 0. + +The VTU shall declare a persistent loss of margin failure after $60 \pm 1$ s of contiguous near-end loss of margin defect (*lom*). + +The VTU shall declare a persistent TPS-TC out-of-sync failure after $15 \pm 1$ s of contiguous near-end TPS-TC out-of-sync condition. + +In the case that the TPS-TC is ATM, the TPS-TC out-of-sync condition corresponds with near-end loss of cell delineation defect (*lcd-n*). (See clause L.2). + +In the case that the TPS-TC is PTM, the TPS-TC out-of-sync condition corresponds with near-end + +TC\_out\_of\_sync (*oos-n*) anomaly. (See clause N.4 of [ITU-T G.992.3]). + +The high\_BER-hs event in *RIpolicyn=1* shall be declared whenever any of the parameters listed in Table 12-4 exceeds the listed threshold. + +**Table 12-4 – Conditions for declaring a high\_BER-hs event in *RIpolicyn=1*** + +| Parameter | Threshold | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------| +| Number of contiguous near-end SES | REINIT_TIME_THRESHOLD configured in CO-MIB | +| Number of successful SOS procedures performed within a 120-second interval | MAX-SOS threshold configured in CO-MIB | +| Number of seconds the actual net data rate ( net_actn ) is below the minimum net data rate ( net_minn ) for any bearer channel after a successful SOS procedure | 20 seconds | +| Duration of time interval with consecutive eoc message time-outs without a single successful eoc command/response exchange | REINIT_TIME_THRESHOLD configured in CO-MIB | +| NOTE – At the VTU-R, no other conditions shall declare a high_BER-hs event. At the VTU-O, no other near-end conditions shall declare a high_BER-hs event. Declaration of a high_BER-hs event based on far-end conditions are vendor specific. | | + +### 12.1.5 Loop diagnostic procedure + +Loop diagnostic mode is intended to identify channel conditions at both ends of the loop without transitioning to the SHOWTIME state. The VTUs will return to the SILENT state after completion of the loop diagnostic mode. Loop diagnostic mode is described in clause 12.4. + +## 12.2 Special operations channel (SOC) + +The SOC provides a bidirectional communication of messages between the VTU-O and the VTU-R to support initialization, fast start-up, and loop diagnostic procedures. + +The SOC has 2 states; active and inactive. Its state is determined by the stages of initialization and is indicated in the timing diagrams in Figures 12-6, 12-9 and 12-11 and described in the signal and message summary tables in clauses 12.3.3, 12.3.4, and 12.3.5. + +### 12.2.1 Message format + +The SOC shall use an HDLC-like format with byte stuffing (octet transparency) and an FCS to monitor errors as specified in [ITU-T G.997.1]. + +The structure of an HDLC frame shall be as illustrated in Figure 12-4. + +| Size in octets | Meaning | Value | +|----------------|----------------------|--------------------| +| 1 | Flag | 7E 16 | +| 1 | Address field | Message index | +| 1 | Control field | Segmentation index | +| Up to 1024 | Information payload | Payload bytes | +| 1 | Frame check sequence | FCS | +| 1 | Frame check sequence | FCS | +| 1 | Flag | 7E 16 | + +**Figure 12-4 – Structure of HDLC frames used in the SOC protocol** + +The message index is dependent on the acknowledgment mode (i.e., AR or RQ) and whether a message is being repeated. It is defined in clause 12.2.2. + +The segmentation index facilitates the message segmentation as described in clause 12.2.6. If no segmentation is used, the segmentation index shall be set to 1116. The number of SOC bytes (before byte stuffing) transmitted in a single HDLC frame shall not exceed 1024. + +### 12.2.2 Communication protocol + +The SOC shall use either an automatic repeat (AR) mode or a repeat request (RQ) mode. + +#### 12.2.2.1 Automatic repeat (AR) mode + +In AR mode, messages encapsulated in HDLC frames shall be automatically repeated. At least four idle flags (7E16) shall be inserted between successive frames. + +The message index shall always be set to 0116 in AR mode. The segmentation index shall be set to 1116 if the message is not segmented, and as specified in clause 12.2.6 if the message is segmented. + +Table 12-5 shows the structure of each HDLC frame in AR mode. + +**Table 12-5 – HDLC frames in AR mode** + +| Field | Content | +|---------------------|------------------------------------------------------------------------| +| Flag | 7E 16 | +| Message index | 01 16 | +| Segmentation index | 11 16 if not segmented;
as in clause 12.2.6 if segmented | +| Information payload | Variable, up to 1024 bytes | +| FCS | Variable | +| FCS | Variable | +| Flag | 7E 16 | + +The sending of a message in AR mode shall be terminated by receipt of an acknowledgment of the message. The acknowledgment may be sent at any time. + +### 12.2.2.2 Repeat request (RQ) mode + +In RQ mode, each message encapsulated in an HDLC frame shall be sent only once. However, the VTU expecting the message shall have the opportunity to request the remote side to repeat the message by sending an O/R-REPEAT\_REQUEST message when the expected message has a wrong FCS or when a time-out has expired. After two unsuccessful O/R-REPEAT\_REQUEST attempts, the activation shall be aborted (i.e., considered an unsuccessful activation). The value of the time-out shall be 2 s. The VTU shall start the time-out counter as it transmits the last byte of the message (segment) and stop the counter as it receives the Control field of the expected incoming message (segment). For the first message (segment) following activation/re-activation of the SOC, the VTU shall count the time-out from this activation time to the reception of the Control field of the message (segment) in accordance with the specific message exchange protocol defined in clauses 12.3.3, 12.3.4, and 12.3.5. + +In RQ mode, a VTU shall never send a message (segment) prior to receiving an acknowledgement of the previously sent message (segment). This acknowledgement could be either a message in accordance with the message exchange protocol of the specific initialization phase, or a special signal (O-P-SYNCHRO or R-P-SYNCHRO), as described in clauses 12.3.3, 12.3.4, and 12.3.5. Once acknowledged, messages (segments) shall not be re-sent. + +Upon entering the RQ mode, the message index shall initially be set to 0116 and shall be incremented by 1 as the acknowledgement of a message is received. The index shall wrap around in case of overflow. The value 0016 has a special meaning, as described below, and shall be skipped. This means that index value FF16 shall be followed by 0116. The index shall not be incremented if an O/R-REPEAT\_REQUEST message is received. The segmentation index shall be set to 1116 if the message is not segmented, and as specified in clause 12.2.6 if the message is segmented. The message index and segmentation index of the message (segment) shall not be changed if the message (segment) is re-sent. + +The message index and segmentation index of the O/R-REPEAT\_REQUEST message shall be set to 0016. These fields shall be ignored by the receiver (because there can be only one unacknowledged message or segment at a time). + +### 12.2.3 Mapping of SOC data + +An SOC message shall contain an integer number of octets. All octets shall be sent LSB first. An SOC message may be subdivided into fields. A field can contain parameter values expressed in more than one byte. In this case, the field shall be split into bytes with the byte containing the MSBs of the parameter value sent first. For example, a field carrying a 16-bit value $m_{15}, \dots, m_0$ shall be split into a first byte $B_0 = m_{15} \dots m_8$ and a second byte $B_1 = m_7 \dots m_0$ . The description of fields for specific messages is given in detail in clauses 12.3.3, 12.3.4, and 12.3.5. All fields that follow the fields defined for a specific message shall be ignored. + +NOTE – If future versions of this Recommendation add extra fields to the ones already defined, for reasons of backward compatibility, these fields must be appended to the currently defined ones. + +Some SOC messages may contain several fields. Some fields can be merged together to form a logical entity called a macro-field, such as "PSD descriptor" and "Bands descriptor", which are described in clause 12.3.3.2.1.1. + +### 12.2.4 SOC idle (O-IDLE, R-IDLE) + +When the VTU-O's SOC is in the active state but idle (i.e., it has no message to send), it shall send O-IDLE. Similarly, the VTU-R shall send R-IDLE when its SOC is in the active state but idle. + +O-IDLE and R-IDLE shall consist of HDLC flags: 7E16. This octet shall be sent repeatedly instead of HDLC frames. + +## 12.2.5 SOC messages + +### 12.2.5.1 Message codes + +The information payload of every SOC message shall start with a one byte field containing a unique code to identify the type of message. For one-byte messages the message code is the entire content of the message. The message codes for all defined messages are shown in Table 12-6. + +NOTE – Other than O/R-REPEAT\_REQUEST and O/R-ACK-SEG, which have special message codes, messages sent by the VTU-O have the MSB equal to ZERO, whilst messages sent by the VTU-R have the MSB equal to ONE. + +**Table 12-6 – Message codes for the SOC messages** + +| SOC message | Message code | Notes | +|---------------------------------------------------|------------------|-------------------------| +| O/R-REPEAT_REQUEST | 55 16 | (Note) | +| O/R-ACK-SEG | 0F 16 | (Note) | +| VTU-O messages | | | +| O-ACK | 00 16 | (Note) | +| O-SIGNATURE | 01 16 | see clause 12.3.3.2.1.1 | +| O-UPDATE | 02 16 | see clause 12.3.3.2.1.2 | +| O-MSG 1 | 03 16 | see clause 12.3.5.2.1.1 | +| O-PRM | 04 16 | see clause 12.3.3.2.1.3 | +| O-TA_UPDATE | 05 16 | see clause 12.3.4.2.1.1 | +| O-TPS | 06 16 | see clause 12.3.5.2.1.2 | +| O-PMS | 07 16 | see clause 12.3.5.2.1.3 | +| O-PMD | 08 16 | see clause 12.3.5.2.1.4 | +| O-PRM-LD | 09 16 | see clause 12.4.2.1.1 | +| O-MSG-LD | 0A 16 | see clause 12.4.3.1.1 | +| VTU-R messages | | | +| R-ACK | 80 16 | (Note) | +| R-MSG 1 | 81 16 | see clause 12.3.3.2.2.1 | +| R-UPDATE | 82 16 | see clause 12.3.3.2.2.2 | +| R-MSG 2 | 83 16 | see clause 12.3.5.2.2.1 | +| R-PRM | 84 16 | see clause 12.3.3.2.2.3 | +| R-TA_UPDATE | 85 16 | see clause 12.3.4.2.2.1 | +| R-TPS-ACK | 86 16 | see clause 12.3.5.2.2.2 | +| R-PMS | 87 16 | see clause 12.3.5.2.2.3 | +| R-PMD | 88 16 | see clause 12.3.5.2.2.4 | +| R-PRM-LD | 89 16 | see clause 12.4.2.1.2 | +| R-MSG-LD | 8A 16 | see clause 12.4.3.1.2 | +| NOTE – This is the entire payload of the message. | | | + +#### 12.2.5.2 O/R-REPEAT\_REQUEST + +This message shall be used in RQ mode to request the remote side to resend the last unacknowledged message (segment), as described in clause 12.2.2.2. The format of the message shall be as specified in clause 12.2.1, and the payload shall be as specified in Table 12-6. + +In AR mode, O/R-REPEAT\_REQUEST messages shall be ignored. + +#### 12.2.5.3 O/R-ACK-SEG + +This message shall be used in RQ mode to acknowledge the reception of intermediate segments of a segmented message, as described in clause 12.2.2.2. The format of the message shall be as specified in clause 12.2.1 and the payload shall be as specified in Table 12-6. + +In AR mode, and when no segmentation is used, any O/R-ACK-SEG messages shall be ignored. + +#### 12.2.5.4 VTU-O and VTU-R messages + +These messages are described in detail in clauses 12.3.3, 12.3.4, and 12.3.5. + +### 12.2.6 Segmentation of messages + +Messages that are larger than the maximum allowed size (1024 bytes) shall be segmented before transmission; messages shorter than 1024 bytes may also be segmented to improve robustness. To allow segmentation, a segmentation index is included in the control field of the HDLC frame. The four MSBs of this field shall indicate the number of segments, to a maximum of 15, into which the message has been segmented. The four LSBs of this field shall indicate the index of the current segment, starting from 116. For example, a segmentation index value of 9316 indicates the third segment of a total of nine. In case the message is not segmented, the value of the field shall be 1116. + +In RQ mode, an acknowledgement (O/R-ACK-SEG) shall be sent for all but the last segment. Typically, the last segment signals the end of the message and will therefore be acknowledged by the reply to the message. The O/R-ACK-SEG message (see Table 12-6) shall be used to acknowledge the reception of the other segments. The O/R-ACK-SEG message shall have its message index assigned by the generic rule defined in clause 12.2.2.2 and shall be increased by 1 when a new segment is received. The segmentation index of each O/R-ACK-SEG message shall be set to 1116. Once acknowledged, segments shall not be retransmitted and re-transmission shall not be requested. + +In AR mode, segmentation shall be done in the same way, but there will be no acknowledgements (O/R-ACK-SEG) between different segments of the same message. Segments shall be sent in sequential order. All segments shall be sent before the message is repeated. + +## 12.3 Initialization procedure + +### 12.3.1 Overview + +Initialization of a VTU-O/VTU-R pair includes the following main tasks: + +- Definition of a common mode of operation (profile, band plan and initial values of basic modulation parameters); +- Synchronization (sample clock alignment and symbol alignment); +- Transfer from the VTU-O to the VTU-R of transmission parameters, including information on the PSD masks to be used, RFI bands (e.g., amateur radio bands) to be protected, and target data rates in both transmission directions; +- Channel identification; +- Noise identification; +- Calculation of framer, interleaver, and coding parameters, as well as the bit loading and gain tables; and +- Exchange of VTU parameters (including RS settings, interleaver parameters, framer settings, bit loading and gain tables). + +The common mode of operation shall be negotiated during the ITU-T G.994.1 handshake phase. Information such as the PSD mask, locations of RFI bands to be notched, and target data rates shall be initially available at the VTU-O through the MIB. + +The time line in Figure 12-5 provides an overview of the initialization procedure, which contains four phases. Following the initial ITU-T G.994.1 handshake phase, upstream power back-off is applied and a full duplex link between the VTU-O and the VTU-R is established during the channel discovery phase to set the PSDs of the transmit signals and the main modulation parameters. During the training phase, any time-domain equalizers (TEQs) and echo cancellers may be trained, and the timing advance is refined. During the channel analysis and exchange phase, the two VTUs shall measure the characteristics of the channel and exchange parameters to be used in showtime. + +![](f4aaee6522d9ab40472939a4a178e5a3_img.jpg) + +| | | | | | +|--------------|----------------------------------|----------------------------|-------------------|----------------------------------------| +| VTU-O | ITU-T G.994.1 handshake (12.3.2) | Channel discovery (12.3.3) | Training (12.3.4) | Channel analysis and exchange (12.3.5) | +| VTU-R | ITU-T G.994.1 handshake (12.3.2) | Channel discovery (12.3.3) | Training (12.3.4) | Channel analysis and exchange (12.3.5) | + +G.992.3(15)\_F 12-5 + +**Figure 12-5 – Overview of initialization procedure** + +The transition to the next phase of initialization shall occur after all tasks in a phase have been completed. A time-out period is defined for each phase to avoid suspension of the initialization procedure. Violation of the time-out or an inability to complete a task results in abortion of the activation process (unsuccessful activation). + +The initialization procedure shall be aborted immediately after any of the following events is discovered: + +- Time-out of any phase; +- Missing or incomplete task during any phase; +- Violation of the initialization protocol during any phase (including time-out for acknowledging an SOC message); or +- Detection of 250 ms of unscheduled silence. + +In all phases, the time-out counter shall be started as the VTU enters the phase and shall be reset upon completion of the phase. The following values for the time-outs shall be used: + +- ITU-T G.994.1 handshake phase: As defined in [ITU-T G.994.1]; +- Channel discovery phase: 10 s; +- Training phase: 10 s; and +- Channel analysis and exchange phase: 10 s. + +Exchange of information between the VTU-O and VTU-R during all phases of initialization, excluding the ITU-T G.994.1 handshake phase, shall be performed using the messaging protocol over the special operations channel (SOC) defined in clause 12.2. + +### 12.3.2 ITU-T G.994.1 handshake phase + +The detailed procedures for the ITU-T G.994.1 handshake phase are defined in [ITU-T G.994.1]. + +### 12.3.2.1 Handshake – VTU-O + +A VTU-O, after power-up, loss of signal, or recovery from errors during the initialization procedure, shall enter the initial ITU-T G.994.1 state, C-SILENT1. The VTU-O may either activate the link or respond to R-TONES-REQ (VTU-R initiated activation) by transitioning to C-TONES. Operation shall then proceed according to the procedures defined in [ITU-T G.994.1]. + +If ITU-T G.994.1 procedures select this Recommendation as the mode of operation, the VTU-O shall continue with ITU-T G.993.2 initialization at the conclusion of ITU-T G.994.1 operation. + +#### 12.3.2.1.1 CL messages + +A VTU-O wishing to indicate ITU-T G.993.2 capabilities in an ITU-T G.994.1 CL message shall do so by setting to ONE the ITU-T G.993.2 SPar(1) bit as defined in Table 11.0.4 of [ITU-T G.994.1]. The NPar(2) (Table 11.67 of [ITU-T G.994.1]) and SPar(2) (Table 11.68 of [ITU-T G.994.1]) fields corresponding to the ITU-T G.993.2 SPar(1) bit are defined in Tables 12-7 and 12-8, respectively. For each ITU-T G.993.2 SPar(2) bit set to ONE, a corresponding NPar(3) field shall also be present (beginning with Table 11.68.1 in clause 9.4 of [ITU-T G.994.1]). Table 12-9 shows the definitions and coding for the VTU-O CL NPar(3) fields. + +**Table 12-7 – VTU-O CL message NPar(2) bit definitions** + +| ITU-T G.994.1 NPar(2) Bit | Definition of NPar(2) bit | +|----------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------| +| All-digital mode | If set to ONE, signifies that the VTU-O supports all-digital mode. | +| Support of downstream virtual noise | If set to ONE, signifies that the VTU-O supports the use of the downstream virtual noise mechanism. | +| Lineprobe | Always set to ONE in a VTU-O CL message. | +| Loop Diagnostic mode | Set to ONE if the VTU-O requests loop diagnostic mode. | +| Support of PSD shaping in US0 | Always set to ONE in a VTU-O CL message. | +| Support of equalized FEXT UPBO | If set to ONE, signifies that the VTU-O supports equalized FEXT UPBO. | +| ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction | See Annex X, Table X.1. | +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | See Annex Y, Table Y.1. | +| Alternative electrical length estimation method | If set to ONE, signifies that the VTU-O supports the Alternative Electrical Length Estimation Method (ELE-M1) | +| Support of downstream SAVN | If set to ONE, signifies that the VTU-O supports the use of the downstream SAVN mechanism. | + +**Table 12-8 – VTU-O CL message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of Spar(2) bit | +|------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Always set to ONE. | +| Bands Upstream | Always set to ONE. | +| Bands Downstream | Always set to ONE. | +| RFI Bands | If set to ONE, indicates that RFI band transmit PSD reductions are enabled. If set to ZERO, indicates that RFI band transmit PSD reductions are disabled (Note 1). | +| Initial IDFT Size ( $2N$ ) | Always set to ONE. | +| CE Lengths | If set to ZERO, indicates that the VTU-O can support only the mandatory CE length of $5N/32$ for the IDFT size equal to $2N$ . If set to ONE, indicates that the VTU-O supports optional CE lengths in addition to the mandatory one. | +| Annex A US0 (Note 2) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex A are supported by the VTU-O. | +| Annex B US0 (Note 2) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex B are supported by the VTU-O. | +| Annex C US0 (Note 2) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex C are supported by the VTU-O. | +| Annex N US0 (Note 2) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex N are supported by the VTU-O. | +| NOTE 1 – The RFI Bands shall apply to both directions of transmission. | | +| NOTE 2 – At least one of these bits shall be set to ONE. | | + +**Table 12-9 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of NPar(3) bits | +|----------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 8 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a and 30a. Each profile supported by the VTU-O is indicated by setting its corresponding bit to ONE. | +| Bands Upstream | For a given band plan as defined in the regional annexes, this NPar(3) field shall include all of the upstream bands in ascending order starting at $f_2$ (as shown in Figure A.1, Table B.1, Figure C.1) and ending at the highest band required for the highest frequency profile for which support is indicated. Up to four upstream bands may be defined. Each band shall be defined by a start subcarrier index and stop subcarrier index using 13 bits per index value. The subcarrier indices shall represent 4.3125 kHz subcarrier spacing. Adjacent upstream bands shall be coded as separate bands. | +| Bands Downstream | For a given band plan as defined in the regional annexes, this NPar(3) field shall include all of the downstream bands in ascending order starting at $f_1$ (as shown in Figure A.1, Table B.1, Figure C.1) and ending at the highest band required for the highest frequency profile for which support is indicated. Up to four downstream bands may be defined. Each band shall be defined by a start subcarrier index and stop subcarrier index using 13 bits per index value. The subcarrier indices shall represent 4.3125 kHz subcarrier spacing. Adjacent downstream bands shall be coded as separate bands. | + +**Table 12-9 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| RFI Bands | This NPar(3) shall indicate in ascending order the start subcarrier index and stop subcarrier index for each RFI band in which the transmit PSD is to be reduced below $-80$ dBm/Hz. Each index is represented by 13 bits. Up to 16 RFI bands may be defined. The subcarrier indices shall represent 4.3125 kHz subcarrier spacing. | +| Initial IDFT Size ( $2N$ ) | This NPar(3) indicates the initial downstream IDFT size that the VTU-O shall use at the beginning of the channel discovery phase, encoded as a number from 7 to 13 representing $n$ , where IDFTsize $2N = 2^n$ | +| CE Lengths | This NPar(3) is a field of 15 bits representing the valid CE lengths: $2N/32$ , $3N/32$ , $4N/32$ , ..., $16N/32$ inclusive. For each CE length that the VTU-O can support, the corresponding bit shall be set to ONE. The bit corresponding to $5N/32$ shall always be set to ONE. | +| Annex A US0 |

A parameter block of 5 octets encoding the Annex A US0 capabilities. This block shall be coded as follows:

  • – Bits 1-6 of octet 1 and bits 1-4 of octet 2 shall be individually set to ONE to indicate support by a VTU-O of the corresponding Annex A US0 masks EU-32 through EU-128.
  • – Bits 1-6 of octet 3 and bits 1-4 of octet 4 shall be individually set to ONE to indicate support by the VTU-O of the corresponding Annex A US0 masks ADLU-32 through ADLU-128.
  • – Bit 1 of octet 5 shall be set to ONE to indicate that all supported Annex A US0 masks are also supported by the VTU-O for profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 5 shall be set to ONE to indicate that all supported Annex A US0 masks are also supported by the VTU-O for profile 17a. This bit may be set to ONE if profile 17a is supported.
  • – Bit 3 of octet 5 shall be set to ONE to indicate that all supported Annex A US0 masks are also supported by the VTU-O for profile 35b. This bit may be set to ONE if profile 35b is supported (Note).
| +| Annex B US0 |

A parameter block of 2 octets encoding the Annex B US0 capabilities. This block shall be coded as follows:

  • – Bits 1-3 of octet 1 shall be individually set to ONE to indicate support of the corresponding Annex B US0 masks by the VTU-O.
  • – Bit 1 of octet 2 shall be set to ONE to indicate that all supported Annex B US0 masks are also supported by the VTU-O for profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 2 shall be set to ONE to indicate that all supported Annex B US0 masks are also supported by the VTU-O for profile 17a. This bit may be set to ONE if profile 17a is supported.
| + +**Table 12-9 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|--------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Annex C US0 |

A parameter block of 3 octets encoding the Annex C US0 capabilities. This block shall be coded as follows:

  • – Bits 1-2 of octet 1 shall be individually set to ONE to indicate the support of the corresponding Annex C US0 Type(b) masks by the VTU-O.
  • – Bits 1-2 of octet 2 shall be individually set to ONE to indicate the support of the corresponding Annex C US0 Type(co) masks by the VTU-O.
  • – Bit 1 of octet 3 shall be set to ONE to indicate that all supported Annex C US0 masks are also supported by the VTU-O in the profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 3 shall be set to ONE to indicate that all supported Annex C US0 masks are also supported by the VTU-O in the profile 17a. This bit may be set to ONE if profile 17a is supported.
| +| Annex N US0 |

A parameter block of 2 octets encoding the Annex N US0 capabilities. This block shall be coded as follows:

  • – Bits 1-3 of octet 1 shall be individually set to ONE to indicate support of the corresponding Annex N US0 masks by the VTU-O.
  • – Bit 2 of octet 2 shall be set to ONE to indicate that all supported Annex N US0 masks are also supported by the VTU-O for profile 17a. This bit may be set to ONE if profile 17a is supported.
  • – Bit 3 of octet 2 shall be set to ONE to indicate that all supported Annex N US0 masks are also supported by the VTU-O for profile 35b. This bit may be set to ONE if profile 35b is supported.
| +| NOTE – The ADLU US0 masks are not applicable to profile 35b. | | + +### 12.3.2.1.2 MS messages + +A VTU-O selecting the ITU-T G.993.2 mode of operation in an ITU-T G.994.1 MS message shall do so by setting to ONE the SPar(1) ITU-T G.993.2 bit as defined in Table 11.0.4 of [ITU-T G.994.1]. The NPar(2) (Table 11.67 of [ITU-T G.994.1]) and SPar(2) (Table 11.68 of [ITU-T G.994.1]) fields corresponding to this bit are defined in Tables 12-10 and 12-11, respectively. For each ITU-T G.993.2 SPar(2) bit set to ONE, a corresponding NPar(3) field shall also be present (beginning with Table 11.68.1 in clause 9.4 of [ITU-T G.994.1]). Table 12-12 shows the definitions and coding for the VTU-O MS NPar(3) fields. + +**Table 12-10 – VTU-O MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) Bit | Definition of NPar(2) bit | +|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| All-digital mode | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that both the VTU-O and the VTU-R shall be configured for operation in all-digital mode. | +| Support of downstream virtual noise | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the downstream virtual noise mechanism may be used. | + +**Table 12-10 – VTU-O MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) Bit | Definition of NPar(2) bit | +|----------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Lineprobe | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the channel discovery phase of initialization shall include a lineprobe stage. | +| Loop Diagnostic mode | Set to ONE if either the last previous CLR or the last previous CL message has set this bit to ONE. Indicates that both VTUs shall enter loop diagnostic mode. | +| Support of PSD shaping in US0 | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the VTU-R supports PSD shaping in the US0 band. | +| Support of equalized FEXT UPBO | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that both the VTU-O and the VTU-R shall use equalized FEXT UPBO. | +| ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction | See Table X.2 | +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | See Table Y.2. | +| Alternative electrical length estimation method | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that both the VTU-O and the VTU-R shall use electrical length estimation method ELE-M1. | +| Support of downstream SAVN | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the downstream SAVN mechanism may be used. | + +**Table 12-11 – VTU-O MS message SPar(2) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of SPar(2) bit | +|--------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Always set to ONE. | +| Bands Upstream | Always set to ZERO. | +| Bands Downstream | Always set to ZERO | +| RFI Bands | Always set to ZERO. | +| Initial IDFT Size ( $2^N$ ) | Always set to ZERO. | +| CE Lengths | Shall be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that the initial CE length to be used by both the VTU-O and the VTU-R shall be communicated in the corresponding NPar(3) field. If set to ZERO, the mandatory value shall be used. | +| Annex A US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| Annex B US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| Annex C US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | + +**Table 12-11 – VTU-O MS message SPar(2) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of SPar(2) bit | +|------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------| +| Annex N US0
(Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| NOTE – One and only one of these bits shall be set to ONE. | | + +**Table 12-12 – VTU-O MS message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 8 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a and 30a. The profile selected by the VTU-O is indicated by setting its corresponding bit to ONE. | +| CE Lengths | This NPar(3) is a field of 15 bits representing the valid CE lengths $2N/32, 3N/32, 4N/32, \dots, 16N/32$ inclusive. The VTU-O shall indicate by setting to ONE the bit corresponding to the selected initial CE length. All other bits shall be set to ZERO. The selected CE length shall be one whose bit was set to ONE in both the last previous CLR and the last previous CL messages. | +| Annex A US0
(Note) | A parameter block of 5 octets encoding the Annex A US0 selection. The VTU-O shall indicate its selection of the Annex A US0 mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-3 of octet 5 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| Annex B US0
(Note) | A parameter block of 2 octets encoding the Annex B US0 selection. The VTU-O shall indicate its selection of the Annex B US0 PSD mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages, and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-2 of octet 2 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| Annex C US0
(Note) | A parameter block of 3 octets encoding the Annex C US0 selection. The VTU-O shall indicate its selection of the Annex C US0 PSD mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages, and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-2 of octet 3 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | + +**Table 12-12 – VTU-O MS message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Annex N US0
(Note) | A parameter block of 2 octets encoding the Annex N US0 selection. The VTU-O shall indicate its selection of the Annex N US0 PSD mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages, and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-3 of octet 2 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| NOTE – Support of US0 means the capability of the VTU-R to transmit US0 and the capability of the VTU-O to receive it. | | + +### 12.3.2.2 Handshake – VTU-R + +A VTU-R, after power-up, loss of signal, or recovery from errors during the initialization procedure, shall enter the initial ITU-T G.994.1 state, R-SILENT0. The VTU-R may activate the link by transitioning to R-TONES-REQ. Alternatively, upon detection of C-TONES (VTU-O initiated activation), the VTU-R may transition to R-TONE1. Operation shall then continue in accordance with the procedures defined in [ITU-T G.994.1]. + +If ITU-T G.994.1 procedures select this Recommendation as the mode of operation, the VTU-R shall continue with ITU-T G.993.2 initialization at the conclusion of ITU-T G.994.1 operation. + +#### 12.3.2.2.1 CLR messages + +A VTU-R wishing to indicate ITU-T G.993.2 capabilities in an ITU-T G.994.1 CLR message shall do so by setting to ONE the ITU-T G.993.2 SPar(1) bit as defined in Table 11.0.4 of [ITU-T G.994.1]. The NPar(2) (Table 11.67 of [ITU-T G.994.1]) and SPar(2) (Table 11.68 of [ITU-T G.994.1]) fields corresponding to the ITU-T G.993.2 SPar(1) bit are defined in Tables 12-13 and 12-14, respectively. For each ITU-T G.993.2 SPar(2) bit set to ONE, a corresponding NPar(3) field shall also be present (beginning with Table 11.68.1 in clause 9.4 of [ITU-T G.994.1]). Table 12-15 shows the definitions and coding for the VTU-R CLR NPar(3) fields. + +**Table 12-13 – VTU-R CLR message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) Bit | Definition of NPar(2) bit | +|-----------------------------------------|-----------------------------------------------------------------------------------------------------| +| All-digital mode | If set to ONE, signifies that the VTU-R supports all-digital mode. | +| Support of downstream virtual noise | If set to ONE, signifies that the VTU-R supports the use of the downstream virtual noise mechanism. | +| Lineprobe | Set to ONE if the VTU-R requests the inclusion of a lineprobe stage in initialization. | +| Loop Diagnostic mode | Set to ONE if the VTU-R requests loop diagnostic mode. | +| Support of PSD shaping in US0 | If set to ONE, signifies that the VTU-R supports PSD shaping in the US0 band. | +| Support of equalized FEXT | If set to ONE, signifies that the VTU-R supports equalized FEXT UPBO. | +| ITU-T G.993.5-friendly
ITU-T G.993.2 | If set to ONE, signifies that the VTU-R supports Annex X. | + +**Table 12-13 – VTU-R CLR message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) Bit | Definition of NPar(2) bit | +|-----------------------------------------------------|---------------------------------------------------------------------------------------------------------------| +| operation in the downstream direction | | +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | If set to ONE, signifies that VTU-R supports Annex Y. | +| Alternative electrical length estimation method | If set to ONE, signifies that the VTU-R supports the Alternative Electrical Length Estimation Method (ELE-M1) | +| Support of downstream SAVN | If set to ONE, signifies that the VTU-R supports the use of the downstream SAVN mechanism. | + +**Table 12-14 – VTU-R CLR message SPar(2) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of SPar(2) bit | +|--------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Always set to ONE. | +| Bands Upstream | Always set to ZERO. | +| Bands Downstream | Always set to ZERO. | +| RFI Bands | Always set to ZERO. | +| Initial IDFT Size ( $2N$ ) | Always set to ONE. | +| CE Lengths | If set to ZERO, indicates that the VTU-R can support only the mandatory CE length of $5N/32$ for the IDFT size equal to $2N$ . If set to ONE, indicates that the VTU-R supports optional CE lengths in addition to the mandatory one. | +| Annex A US0 (Note) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex A are supported by the VTU-R. | +| Annex B US0 (Note) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex B are supported by the VTU-R. | +| Annex C US0 (Note) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex C are supported by the VTU-R. | +| Annex N US0 (Note) | If set to ONE, indicates that the corresponding NPar(3) shall indicate which of the US0 PSD masks described in Annex N are supported by the VTU-R. | +| NOTE – At least one of these bits shall be set to ONE. | | + +**Table 12-15 – VTU-R CLR message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 8 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a and 30a. Each profile supported by the VTU-R is indicated by setting its corresponding bit to ONE. | +| Initial IDFT Size ( $2N$ ) | This NPar(3) indicates the initial upstream IDFT size that the VTU-R shall use at the beginning of the channel discovery phase, encoded as a number from 6 to 13 representing $n$ , where IDFTsize $2N = 2^n$ | +| CE Lengths | This NPar(3) is a field of 15 bits representing the valid CE lengths $2N/32$ , $3N/32$ , $4N/32$ , ..., $16N/32$ , inclusive. For each supported CE length, the corresponding bit shall be set to ONE. The bit corresponding to $5N/32$ shall always be set to ONE. | +| Annex A US0 |

A parameter block of 5 octets encoding the Annex A US0 capabilities. This block shall be coded as follows:

  • – Bits 1-6 of octet 1 and bits 1-4 of octet 2 shall be individually set to ONE to indicate support by a VTU-R of Annex A US0 masks EU-32 through EU-128. If bit 4 of octet 2 is set to ONE, the VTU-R shall also set the "Support of PSD shaping in US0" NPar(2) bit to ONE (see Table 12-13).
  • – Bits 1-6 of octet 3 and bits 1-4 of octet 4 shall be individually set to ONE to indicate support by the VTU-R of Annex A US0 masks ADLU-32 through ADLU-128. If bit 4 of octet 4 is set to ONE, the VTU-R shall also set the "Support of PSD shaping in US0" NPar(2) bit to ONE (see Table 12-13).
  • – Bit 1 of octet 5 shall be set to ONE to indicate that all supported Annex A US0 masks are also supported by the VTU-R in the profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 5 shall be set to ONE to indicate that all supported Annex A US0 masks are also supported by the VTU-R in the profile 17a. This bit may be set to ONE if profile 17a is supported.
  • – Bit 3 of octet 5 shall be set to ONE to indicate that all supported Annex A US0 masks are also supported by the VTU-R in the profile 35b. This bit may be set to ONE if profile 35b is supported (Note).
| +| Annex B US0 |

A parameter block of 2 octets encoding the Annex B US0 capabilities. This block shall be coded as follows:

  • – Bits 1-3 of octet 1 shall be individually set to ONE to indicate support of the corresponding Annex B US0 masks by the VTU-R.
  • – Bit 1 of octet 2 shall be set to ONE to indicate that all supported Annex B US0 masks are also supported by the VTU-R for profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 2 shall be set to ONE to indicate that all supported Annex B US0 masks are also supported by the VTU-R for profile 17a. This bit may be set to ONE if profile 17a is supported.
| +| Annex C US0 |

A parameter block of 3 octets encoding the Annex C US0 capabilities. This block shall be coded as follows:

  • – Bits 1-2 of octet 1 shall be individually set to ONE to indicate the support of the corresponding Annex C US0 Type(b) masks by the VTU-R.
  • – Bits 1-2 of octet 2 shall be individually set to ONE to indicate the support of the corresponding Annex C US0 Type(co) masks by the VTU-R.
| + +**Table 12-15 – VTU-R CLR message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|--------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| |
  • – Bit 1 of octet 3 shall be set to ONE to indicate that all supported Annex C US0 masks are also supported by the VTU-R in the profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 3 shall be set to ONE to indicate that all supported Annex C US0 masks are also supported by the VTU-R in the profile 17a. This bit may be set to ONE if profile 17a is supported.
| +| Annex N US0 |

A parameter block of 2 octets encoding the Annex N US0 capabilities. This block shall be coded as follows:

  • – Bits 1-3 of octet 1 shall be individually set to ONE to indicate support of the corresponding Annex N US0 masks by the VTU-R.
  • – Bit 1 of octet 2 shall be set to ONE to indicate that all supported Annex N US0 masks are also supported by the VTU-R for profile 12b. This bit may be set to ONE if profile 12b is supported.
  • – Bit 2 of octet 2 shall be set to ONE to indicate that all supported Annex N US0 masks are also supported by the VTU-R for profile 17a. This bit may be set to ONE if profile 17a is supported.
  • – Bit 3 of octet 2 shall be set to ONE to indicate that all supported Annex N US0 masks are also supported by the VTU-R for profile 35b. This bit may be set to ONE if profile 35b is supported.
| +| NOTE – The ADLU US0 masks are not applicable to profile 35b. | | + +#### 12.3.2.2.2 MS messages + +A VTU-R selecting ITU-T G.993.2 mode of operation in an ITU-T G.994.1 MS message shall do so by setting to ONE the ITU-T G.993.2 SPar(1) bit as defined in Table 11.0.4 of [ITU-T G.994.1]. The NPar(2) (Table 11.67 of [ITU-T G.994.1]) and SPar(2) (Table 11.68 of [ITU-T G.994.1]) fields corresponding to the ITU-T G.993.2 SPar(1) bit are defined in Tables 12-16 and 12-17, respectively. For each ITU-T G.993.2 SPar(2) bit set to ONE, a corresponding NPar(3) field shall also be present (beginning with Table 11.68.1 in clause 9.4 of [ITU-T G.994.1]). Table 12-18 shows the definitions and coding for the VTU-R MS NPar(3) fields. + +**Table 12-16 – VTU-R MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) Bit | Definition of NPar(2) bit | +|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| All-digital mode | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that both the VTU-O and the VTU-R shall be configured for operation in all-digital mode. | +| Support of downstream virtual noise | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the downstream virtual noise mechanism may be used. | +| Lineprobe | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the channel discovery phase of initialization shall include a lineprobe stage. | +| Loop Diagnostic mode | Set to ONE if either the last previous CLR or the last previous CL message has set this bit to ONE. Indicates that both VTUs shall enter loop diagnostic mode. | + +**Table 12-16 – VTU-R MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) Bit | Definition of NPar(2) bit | +|-------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of PSD shaping in US0 | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the VTU-R shall support PSD shaping in the US0 band. | +| Support of equalized FEXT | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that both the VTU-O and the VTU-R shall use equalized FEXT UPBO. | +| ITU-T G.993.5-friendly
ITU-T G.993.2 operation in the downstream direction | See Table X.4 | +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | See Table Y.4. | +| Alternative electrical length estimation method | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that both the VTU-O and the VTU-R shall use ELE-M1. | +| Support of downstream SAVN | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. Indicates that the downstream SAVN mechanism may be used. | + +**Table 12-17 – VTU-R MS message SPar(2) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of SPar(2) bit | +|------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Always set to ONE. | +| Bands Upstream | Always set to ZERO. | +| Bands Downstream | Always set to ZERO | +| RFI Bands | Always set to ZERO. | +| Initial IDFT Size ( $2N$ ) | Always set to ZERO. | +| CE Lengths | Shall be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that the initial CE length to be used by both the VTU-O and the VTU-R shall be communicated in the corresponding NPar(3) field. If set to ZERO, the mandatory value shall be used. | +| Annex A US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| Annex B US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| Annex C US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| Annex N US0 (Note) | May be set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. | +| NOTE – One and only one of these bits shall be set to ONE. | | + +**Table 12-18 – VTU-R MS message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 8 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a and 30a. The profile selected by the VTU-R is indicated by setting its corresponding bit to ONE. | +| CE Lengths | This NPar(3) is a field of 15 bits representing the valid CE lengths 2N/32, 3N/32, 4N/32, ..., 16N/32, inclusive. The VTU-R shall indicate by setting to ONE the bit corresponding to the selected initial CE length. All other bits shall be set to ZERO. The selected CE length shall be one whose bit was set to ONE in both the last previous CLR and the last previous CL messages. | +| Annex A US0
(Note) | A parameter block of 5 octets encoding the Annex A US0 selection. The VTU-R shall indicate its selection of the Annex A US0 mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-3 of octet 5 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| Annex B US0
(Note) | A parameter block of 2 octets encoding the Annex B US0 selection. The VTU-R shall indicate its selection of the Annex B US0 mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-2 of octet 2 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| Annex C US0
(Note) | A parameter block of 3 octets encoding the Annex C US0 selection. The VTU-R shall indicate its selection of the Annex C US0 mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-2 of octet 3 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| Annex N US0
(Note) | A parameter block of 2 octets encoding the Annex N US0 selection. The VTU-R shall indicate its selection of the Annex N US0 mask by setting to ONE the bit corresponding to that PSD mask. No more than one bit in this NPar(3) shall be set to ONE. The selected bit shall be set to ONE if and only if it was set to ONE in both the last previous CLR and the last previous CL messages and the selected profile supports US0 either explicitly or implicitly by its definition in Table 6-1. Bits 1-3 of octet 2 shall always be set to ZERO. If all bits are set to ZERO, the US0 band shall not be enabled. | +| NOTE – Support of US0 means the capability of the VTU-R to transmit US0 and the capability of the VTU-O to receive it. | | + +### 12.3.3 Channel discovery phase + +#### 12.3.3.1 Overview + +The channel discovery phase is the first phase when VDSL2 signals are exchanged between VTUs. The following tasks are completed during channel discovery: + +- Timing recovery and selection of pilot tone(s); +- Establish communication between the VTUs over the SOC; +- Exchange information necessary to set up the PSDs for both transmission directions; and +- Verify, adjust and exchange various parameter values necessary to enter the training phase (IDFT sizes, CE length, window length and others). + +During the channel discovery phase, if the optional equalized FEXT UPBO method is not supported, the VTU-R shall determine the required UPBO based on the estimation of the electrical length of the loop and on the values of parameters for the UPBO reference PSD (UPBOPSD) it receives from the VTU-O. If the optional equalized FEXT UPBO method is supported, the VTU-R shall use in addition the parameter UPBO reference electrical length (UPBOREFEL) it receives from the VTU-O, to determine the required UPBO. Both VTUs may perform additional PSD cut-back. + +NOTE 1 – In regions of the spectrum not expected to be useable in showtime, the transceiver may reduce the value of the PSD from the beginning of channel discovery to prevent unnecessary crosstalk into other systems. A VTU may, for example, determine the tones where CDPSD can be reduced based on the received signal level and known transmit level of the ITU-T G.994.1 tones. A specific mechanism is vendor discretionary. + +Figure 12-6 presents the timing diagram for the stages of the channel discovery phase. It gives an overview of the sequence of signals transmitted and the sequence of SOC messages sent by the VTU-O and VTU-R during the channel discovery phase. The two inner columns show the sequences of signals that are transmitted (see clause 12.3.3.3). The two outer columns show the messages that are sent over the SOC (see clause 12.3.3.2). The shaded areas correspond to periods of time when the SOC is in its inactive state. + +![Timing diagram for the stages of the channel discovery phase. The diagram shows the sequence of signals and SOC messages exchanged between Downstream and Upstream entities. The vertical axis represents time, and the horizontal axis separates Downstream and Upstream. The 'CHANNEL DISCOVERY phase (VTU-O)' is indicated on the left, and 'CHANNEL DISCOVERY phase (VTU-R)' on the right. The sequence includes O-IDLE, O-SIGNATURE, O-P-QUIET 1, O-P-CHANNEL-DISCOVERY 1, O-P-SYNCHRO 1, O-P-QUIET 2, O-P-PILOT 1, O-P-PERIODIC 1, O-P-SYNCHRO 2, O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, O-IDLE, and O-P-SYNCHRO 3 on the Downstream side. On the Upstream side, the sequence includes ITU-T G.994.1 Handshake, R-P-QUIET 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1, R-P-LINEPROBE, R-P-PERIODIC 1, R-P-SYNCHRO 2, R-IDLE, R-UPDATE, R-IDLE, R-PRM, R-IDLE, and R-P-SYNCHRO 3. SOC Messages on the Downstream side include O-IDLE, O-SIGNATURE, O-P-QUIET 1, O-P-CHANNEL-DISCOVERY 1, O-P-SYNCHRO 1, O-P-QUIET 2, O-P-PILOT 1, O-P-PERIODIC 1, O-P-SYNCHRO 2, O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, O-IDLE, and O-P-SYNCHRO 3. SOC Messages on the Upstream side include ITU-T G.994.1 Handshake, R-P-QUIET 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1, R-P-LINEPROBE, R-P-PERIODIC 1, R-P-SYNCHRO 2, R-IDLE, R-UPDATE, R-IDLE, R-PRM, R-IDLE, and R-P-SYNCHRO 3.](fd4b2ee19b709bcb11190893e23f8453_img.jpg) + +| Downstream | | Upstream | | +|--------------|-------------------------|-------------------------|--------------| +| SOC Messages | Signals | Signals | SOC Messages | +| | ITU-T G.994.1 Handshake | ITU-T G.994.1 Handshake | | +| | O-P-QUIET 1 | | | +| O-IDLE | | R-P-QUIET 1 | | +| | O-P-CHANNEL-DISCOVERY 1 | | | +| O-SIGNATURE | | R-P-CHANNEL-DISCOVERY 1 | R-IDLE | +| | O-P-SYNCHRO 1 | | R-MSG 1 | +| | O-P-QUIET 2 | R-P-SYNCHRO 1 | | +| | O-P-PILOT 1 | R-P-LINEPROBE | | +| | O-P-PERIODIC 1 | R-P-PERIODIC 1 | | +| | O-P-SYNCHRO 2 | R-P-SYNCHRO 2 | | +| O-IDLE | | | | +| O-UPDATE | | | R-IDLE | +| O-IDLE | | | | +| O-PRM | | | R-UPDATE | +| O-IDLE | | | | +| O-ACK | | | R-IDLE | +| O-IDLE | | | | +| | O-P-SYNCHRO 3 | R-P-SYNCHRO 3 | | + +Timing diagram for the stages of the channel discovery phase. The diagram shows the sequence of signals and SOC messages exchanged between Downstream and Upstream entities. The vertical axis represents time, and the horizontal axis separates Downstream and Upstream. The 'CHANNEL DISCOVERY phase (VTU-O)' is indicated on the left, and 'CHANNEL DISCOVERY phase (VTU-R)' on the right. The sequence includes O-IDLE, O-SIGNATURE, O-P-QUIET 1, O-P-CHANNEL-DISCOVERY 1, O-P-SYNCHRO 1, O-P-QUIET 2, O-P-PILOT 1, O-P-PERIODIC 1, O-P-SYNCHRO 2, O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, O-IDLE, and O-P-SYNCHRO 3 on the Downstream side. On the Upstream side, the sequence includes ITU-T G.994.1 Handshake, R-P-QUIET 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1, R-P-LINEPROBE, R-P-PERIODIC 1, R-P-SYNCHRO 2, R-IDLE, R-UPDATE, R-IDLE, R-PRM, R-IDLE, and R-P-SYNCHRO 3. SOC Messages on the Downstream side include O-IDLE, O-SIGNATURE, O-P-QUIET 1, O-P-CHANNEL-DISCOVERY 1, O-P-SYNCHRO 1, O-P-QUIET 2, O-P-PILOT 1, O-P-PERIODIC 1, O-P-SYNCHRO 2, O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, O-IDLE, and O-P-SYNCHRO 3. SOC Messages on the Upstream side include ITU-T G.994.1 Handshake, R-P-QUIET 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1, R-P-LINEPROBE, R-P-PERIODIC 1, R-P-SYNCHRO 2, R-IDLE, R-UPDATE, R-IDLE, R-PRM, R-IDLE, and R-P-SYNCHRO 3. + +**Figure 12-6 – Timing diagram for the stages of the channel discovery phase** + +NOTE 2 – In the exchange of the SOC messages identified in Figure 12-6, the rules of the communication protocol of clause 12.2.2 apply. Some messages sent in the SOC may require segmentation; although this is not shown in Figure 12-6, the segmented message elements and their corresponding acknowledgements are sent via the SOC per the communication protocol of clause 12.2.2. + +The VTU-O shall initiate the start of the channel discovery phase with O-P-QUIET 1. During this stage, both VTUs are silent and a quiet line noise measurement can be performed. The duration of O-P-QUIET 1 shall be at least 512 symbols but not longer than 1024 symbols. After completing the O-P-QUIET 1 stage, the VTU-O shall start transmitting O-P-CHANNEL DISCOVERY 1. The VTU-O shall send O-IDLE for a period of between 1500 and 2000 DMT symbols. It shall then send its first message, O-SIGNATURE. O-SIGNATURE shall be sent over the SOC in AR mode, as described in clause 12.2.2.1, and carries the information listed in Table 12-21. + +The VTU-R shall start the channel discovery phase with R-P-QUIET 1 (no signal) until it correctly receives the O-SIGNATURE message. During the R-P-QUIET 1 stage, the VTU-R shall complete the timing lock prior to transmitting R-P-CHANNEL DISCOVERY 1. Upon receiving the O-SIGNATURE message, the VTU-R has all of the necessary information needed to perform UPBO (see clause 7.2.1.3). If AELE-MODE = 1, 2, or 3, UPBO shall be performed according to AELE-MODE=1 until final $kI_0$ values are provided in the O-UPDATE message. After performing UPBO, the VTU-R shall transmit R-P-CHANNEL DISCOVERY 1. The VTU-R shall transmit R-P-CHANNEL DISCOVERY 1 using the initial timing advance value received in the O-SIGNATURE message. The VTU-R shall send R-IDLE for at least 512 DMT symbols. It shall then send its first message, R-MSG 1, in AR mode. The VTU-R shall send R-MSG 1 until the VTU-O indicates it has correctly received R-MSG 1. The R-MSG 1 message conveys to the VTU-O the upstream PSD and other VTU-R parameters, as presented in Table 12-32. + +The VTU-O shall indicate correct reception of the R-MSG 1 message by transmitting O-P-SYNCHRO 1, which shall be followed by transmission of O-P-PERIODIC 1 if a lineprobe stage is not requested. If a lineprobe stage is requested, the VTU-O shall transmit O-P-QUIET 2/O-P-PILOT 1 and transition to O-P-PERIODIC 1 640 symbols after the end of transmission of O-P-SYNCHRO 1. The request for a lineprobe stage is indicated by the parameter "Lineprobe" during the ITU-T G.994.1 handshake phase (see clause 12.3.2). + +The VTU-R shall reply to O-P-SYNCHRO 1 by transmitting R-P-SYNCHRO 1 within a time period of 64 symbols after detection of O-P-SYNCHRO 1. This shall be followed by transmission of either R-P-PERIODIC 1 if a lineprobe stage is not requested, or R-P-LINEPROBE if a lineprobe stage is requested. The duration of R-P-LINEPROBE shall be 512 symbols. After R-P-LINEPROBE, the VTU-R shall transmit R-P-PERIODIC 1. + +The VTU-O shall transmit O-P-PERIODIC 1 for a duration of 2 048 symbols and shall then transition to O-P-SYNCHRO 2. The VTU-R shall transmit R-P-PERIODIC 1 for a duration of 2 048 symbols and shall then transition to R-P-SYNCHRO 2. During the period of time that O-P-PERIODIC 1 and R-P-PERIODIC 1 are transmitted, the VTUs may perform SNR measurements. + +Immediately after transmission of O-P-SYNCHRO 2, the VTU-O shall transmit O-P-CHANNEL DISCOVERY 2 while sending O-IDLE over the SOC. + +After detection of R-P-SYNCHRO 2 and the end of transmission of O-P-SYNCHRO 2, the VTU-O shall send O-UPDATE after a time period of between 48 and 64 symbols, inclusive, to update the parameters of the VTU-R, specifically the PSD of the VTU-R. The O-UPDATE message may also include corrections to the UPBO settings, and additional power cut-back. The parameters conveyed by O-UPDATE are presented in Table 12-28. + +The O-UPDATE message and all subsequent SOC messages from the VTU-O shall be sent only once, using the RQ protocol described in clause 12.2.2.2, which allows the receiving VTU to ask for a retransmission of incorrectly received or missing messages. + +The VTU-R shall start transmitting R-P-CHANNEL DISCOVERY 2 immediately after transmission of R-P-SYNCHRO 2, while sending R-IDLE over the SOC. All messages sent by the VTU-R starting from those sent during R-P-CHANNEL DISCOVERY 2 shall be sent using the RQ protocol described in clause 12.2.2.2. + +After the VTU-R receives the O-UPDATE message, it shall send R-UPDATE to request an update of the downstream PSD and other parameters of the VTU-O, which may include downstream power cut-back. The list of parameters subject to update at the VTU-O and the VTU-R are listed in Table 12-35 and Table 12-28, respectively. + +The R-UPDATE message shall be acknowledged by the VTU-O by sending O-PRM over the SOC. O-PRM shall contain the final values of the modulation parameters and PSDs to be used in the training phase. The content of O-PRM is presented in Table 12-30. The VTU-R shall acknowledge O-PRM by sending R-PRM (see Table 12-36), which reports settings of VTU-R modulation parameters, including those requested to be updated in O-UPDATE. + +The VTU-O shall acknowledge the reception of the R-PRM message by sending O-ACK. Upon reception of the O-ACK message, the VTU-R shall complete the channel discovery phase in the upstream direction by transmitting R-P-SYNCHRO 3. The VTU-O shall reply by transmitting O-P-SYNCHRO 3 within a time period of 64 symbols. The transmission of O-P-SYNCHRO 3 completes the channel discovery phase in the downstream direction. + +All parameter value changes and PSD changes negotiated during the channel discovery phase relative to those indicated in O-SIGNATURE and R-MSG 1 shall be applied in the downstream direction from the first symbol following O-P-SYNCHRO 3 and in the upstream direction from the first symbol following R-P-SYNCHRO 3. + +NOTE 3 – A change in modulation parameters (such as CE length) may result in the transmission of several corrupt symbols in the downstream direction and a temporary loss of synchronization at the VTU-R receiver. At the start of the training phase, there is a period of time to recover synchronization. + +The signals and SOC messages sent by the VTU-O during the channel discovery phase are summarized in Table 12-19, and the signals and SOC messages sent by the VTU-R during the channel discovery phase are summarized in Table 12-20. The protocol used for SOC messages is provided, where applicable, in parentheses in the column labelled "SOC state". + +**Table 12-19 – VTU-O signals and SOC messages in the channel discovery phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages | SOC state | +|-------------------------|--------------|----------------------------------------|---------------------------|-------------| +| O-P-QUIET 1 | None | 512 to 1024 | None | Inactive | +| O-P-CHANNEL DISCOVERY 1 | Non-periodic | Variable | O-SIGNATURE | Active (AR) | +| O-P-SYNCHRO 1 | Non-periodic | 15 | None | Inactive | +| O-P-PILOT 1 | Non-periodic | 640 | None | Inactive | +| O-P-QUIET 2 | None | 640 | None | Inactive | +| O-P-PERIODIC 1 | Periodic | 2048 | None | Inactive | +| O-P-SYNCHRO 2 | Non-periodic | 15 | None | Inactive | +| O-P-CHANNEL DISCOVERY 2 | Non-periodic | Variable | O-UPDATE,
O-PRM, O-ACK | Active (RQ) | +| O-P-SYNCHRO 3 | Non-periodic | 15 | None | Inactive | + +**Table 12-20 – VTU-R signals and SOC messages in the channel discovery phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages | SOC state | +|-------------------------|----------------------|----------------------------------------|--------------------|-------------| +| R-P-QUIET 1 | None | Variable | None | Inactive | +| R-P-CHANNEL DISCOVERY 1 | Non-periodic | Variable | R-MSG 1 | Active (AR) | +| R-P-SYNCHRO 1 | Non-periodic | 15 | None | Inactive | +| R-P-LINEPROBE | Vendor Discretionary | 512 | None | Inactive | +| R-P-PERIODIC 1 | Periodic | 2048 | None | Inactive | +| R-P-SYNCHRO 2 | Non-periodic | 15 | None | Inactive | +| R-P-CHANNEL DISCOVERY 2 | Non-periodic | Variable | R-UPDATE,
R-PRM | Active (RQ) | +| R-P-SYNCHRO 3 | Non-periodic | 15 | None | Inactive | + +### 12.3.3.2 SOC message exchange during the channel discovery phase + +Figure 12-7 illustrates the SOC message exchange between the VTU-O and VTU-R during the channel discovery phase. It also summarizes the content of each message. + +The messages sent by the VTU-O are described in detail in clause 12.3.3.2.1. The messages sent by the VTU-R are described in detail in clause 12.3.3.2.2. + +![](36790164991deef00875cc7875965a92_img.jpg) + +| | | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +|

O-SIGNATURE (see Table 12-21)

  • Information on downstream (DS) and upstream (US) PSDs and spectrum use
  • DS modulation parameters in channel discovery phase
  • Maximum target total data rate
  • Margin parameters
  • Transmitter-referred virtual noise PSD parameters
| | +| |

R-MSG 1 (see Table 12-32)

  • Information on US PSD
  • US modulation parameters in channel discovery phase
  • Indication of selected pilot tones
| +|

O-UPDATE (see Table 12-28)

  • US PSD and timing advance modification request
  • Conveys US blackout subcarriers
| | +| |

R-UPDATE (see Table 12-35)

  • DS PSD modification request
  • Conveys DS blackout subcarriers
| +|

O-PRM (see Table 12-30)

  • DS MEDLEY reference PSD and spectrum use
  • Updated DS modulation parameters for use in training phase and thereafter
  • Request for training phase durations
| | +| |

R-PRM (see Table 12-36)

  • US MEDLEY reference PSD and spectrum use
  • Updated upstream modulation parameters for use in training phase and thereafter
  • Request for training phase durations
| +|

O-ACK

  • Acknowledgement of R-PRM
| | + +**Figure 12-7 – SOC message exchange during the channel discovery phase** + +### 12.3.3.2.1 VTU-O messages sent during the channel discovery phase + +#### 12.3.3.2.1.1 O-SIGNATURE + +The full list of parameters carried by the O-SIGNATURE message is shown in Table 12-21. + +**Table 12-21 – Description of message O-SIGNATURE** + +| | Field name | Format | +|----|-----------------------------------------------------------------------------|--------------------------------------| +| 1 | Message descriptor | Message code | +| 2 | Supported subcarriers in the downstream direction (SUPPORTEDCARRIERSds set) | Bands descriptor | +| 3 | Supported subcarriers in the upstream direction (SUPPORTEDCARRIERSus set) | | +| 4 | Downstream transmit PSD mask (PSDMASKds) | PSD descriptor | +| 5 | Upstream transmit PSD mask (PSDMASKus) | | +| 6 | Channel discovery downstream PSD (CDPSDds) | | +| 7 | Initial downstream PSD ceiling (CDMAXMASKds) | 2 bytes | +| 8 | Downstream nominal maximum aggregate transmit power (MAXNOMATPds) | 2 bytes | +| 9 | Parameters for UPBO reference PSD (UPBOPSD) | UPBOPSD descriptor | +| 10 | Maximum target total data rate | 2 bytes | +| 11 | Downstream maximum SNR margin (MAXSNRMds) | 2 bytes | +| 12 | Downstream target SNR margin (TARSNRMds) | 2 bytes | +| 13 | Downstream transmit window length ( $\beta_{ds}$ ) | 1 byte | +| 14 | Downstream cyclic prefix | 2 bytes | +| 15 | Initial value of timing advance | 2 bytes | +| 16 | Downstream transmitter-referred virtual noise PSD (TXREFVNdS) | PSD descriptor | +| 17 | SNRM_MODE | 1 byte | +| 18 | Upstream transmitter-referred virtual noise PSD (TXREFVNus) | PSD descriptor | +| 19 | UPBO reference electrical length (UPBOREFEL) | UPBOREFEL descriptor | +| 20 | ITU-T G.998.4 parameter field | Variable length | +| 21 | ITU-T G.993.5 parameter field A | Variable length | +| 22 | Alternative electrical length estimation mode control | 2 bytes AELE-MODE Control descriptor | +| 23 | Reserved for operation according to Annex X | 1 byte | +| 24 | ITU-T G.993.5 parameter field B | Variable length | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Supported subcarriers in the downstream direction (SUPPORTEDCARRIERSds)" conveys information about the subcarriers that are allocated for transmission in the downstream direction. It allows the operator to specify exactly which subcarriers are available for the downstream direction. No more than 32 bands shall be specified. + +Field #3 "Supported subcarriers in the upstream direction (SUPPORTEDCARRIERSus)" conveys information about the subcarriers that are allocated for transmission in the upstream direction. It allows the operator to specify exactly which subcarriers are available for the upstream direction. No more than 32 bands shall be specified. + +Fields #2 and #3 shall be formatted as "bands descriptors". The format of the bands descriptor shall be as shown in Table 12-22. + +**Table 12-22 – Bands descriptor** + +| Octet | Content of field | +|---------------------|----------------------------------------------------------------------------------------------------------| +| 1 | Number of bands to be described | +| 2-4 | Bits 0-11: Index of the first subcarrier in band 1
Bits 12-23: Index of the last subcarrier in band 1 | +| 5-7 (if applicable) | Bits 0-11: Index of the first subcarrier in band 2
Bits 12-23: Index of the last subcarrier in band 2 | +| etc. | etc. | + +The first octet of the bands descriptor shall contain the number of bands to be described. This number can be zero. In that case, there shall be no further octets in the descriptor. If the number of bands is not equal to zero, each group of three consecutive octets in the descriptor shall describe the first and last subcarrier in a band. + +The first 12 bits (0-11) in the group of three octets shall contain the index of the subcarrier at the lower edge of the band. The last 12 bits (12-23) shall contain the index of the subcarrier at the upper edge of the band. The first and last subcarriers shall be included in the band. For example, a field value $400200_{16}$ means that all subcarriers from $200_{16} = 512$ to $400_{16} = 1024$ , including subcarriers 512 and 1024, are included in the set. + +Field #4 "Downstream transmit PSD mask (PSDMASKds)" indicates the PSD mask, for both the passband and the stopbands (see clauses 7.2.1 and 7.2.2), that is allowed in the downstream direction. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 48$ . This information shall be taken into account when performing the downstream PSD updates during the channel discovery phase. The VTU-O shall comply with this constraint at all times. In addition, VTU-O shall comply with the requirements in the RFI bands specified during the ITU-T G.994.1 handshake phase, as specified in clause 12.3.2. + +Field #5 "Upstream transmit PSD mask (PSDMASKus)" indicates the PSD mask, for both the passband and the stopbands (see clauses 7.2.1 and 7.2.2), that is allowed in the upstream direction. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 32$ . This information shall be taken into account when performing the upstream PSD updates during the channel discovery phase. The VTU-R shall comply with this constraint at all times. In addition, the VTU-R shall always comply with the UPBO requirements, which may further reduce the upstream transmit PSD to below the upstream transmit PSD mask, as specified in clause 7.2.1.3, and with the requirements in the RFI bands specified during the ITU-T G.994.1 handshake phase, as specified in clause 12.3.2. + +Field #6 "Channel discovery downstream PSD (CDPSDds)" indicates the PSD at the U interface in the downstream direction during the channel discovery phase. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 48$ . The only valid PSD values obtained by the receiver using the interpolation procedure specified are for those subcarriers that belong to the SUPPORTEDCARRIERSds set, excluding the RFI bands communicated during the ITU-T G.994.1 handshake phase. PSD values out of this set shall be ignored by the receiver. The valid CDPSDds values shall be at least 3.5 dB below the downstream transmit + +PSD mask (Field #4) and at least 3.5 dB below the initial downstream PSD ceiling (Field #7). Moreover, the valid values of CDPSDds, either those which are directly communicated or those obtained at the receiver by interpolation, shall not deviate from the actual values of the transmit PSD, as measured in the reference impedance at the U interface, by more than 1 dB. + +**Table 12-23 – PSD descriptor** + +| Octet | Content of field | +|---------------------|---------------------------------------------------------------------------------------------------------------------------------| +| 1 | Number of subcarriers (or breakpoints) being described | +| 2-4 | Bits 0-11: Index of first subcarrier being described
Bits 12-23: PSD level in steps of 0.1 dB with an offset of –140 dBm/Hz | +| 5-7 (if applicable) | Bits 0-11: Index of second subcarrier being described
Bits 12-23: PSD level in steps of 0.1 dB with an offset of –140 dBm/Hz | +| etc. | etc. | + +The first octet of the descriptor shall contain the number of breakpoints being specified. This number can be zero. In that case, there shall be no additional octets in the descriptor. If the number of breakpoints is not equal to zero, each group of three consecutive octets shall describe one breakpoint as a PSD value at a certain subcarrier index. + +The first 12 bits (0-11) in the group of three octets shall contain the index of the subcarrier. The last 12 bits (12-23) shall contain the PSD level. The PSD level shall be an integer multiple of 0.1 dB with an offset of –140 dBm/Hz. For example, a field value of $320400_{16}$ means a PSD of $320_{16} \times 0.1 - 140 = -60$ dBm/Hz on subcarrier index $400_{16} = 1024$ . The PSD level of intermediate unspecified subcarriers shall be obtained using a linear interpolation between the given PSD points (in dBm/Hz) with the frequency axis expressed in a linear scale. The subcarrier indices of the specified breakpoints may be either determined by the CO-MIB or vendor discretionary. + +NOTE 1 – Breakpoints should be selected such that the PSD between the breakpoints obtained using linear interpolation is sufficiently close to the PSD that is being described. + +Field #7 "Initial downstream PSD ceiling (CDMAXMASKds)" indicates the PSD level that is used to impose a ceiling on the downstream transmit PSD mask to form the downstream PSD mask of the signals transmitted during the channel discovery phase, on which the downstream channel discovery PSD (CDPSDds) is based (see Field #6). The field shall be coded as a 16-bit value with the LSB weight of –0.1 dBm/Hz. The valid values are in the range from 0 dBm/Hz to –90 dBm/Hz in 0.1 dB steps. + +Field #8 "Downstream nominal maximum aggregate transmit power (MAXNOMATPds)" indicates the maximum wide-band power that the VTU-O is allowed to transmit. The value shall be expressed in dBm (10.3.4.2.1). This field shall be coded as a 9-bit twos complement signed integer with the LSB weight of 0.1 dBm and the valid range from –25.6 dBm to +25.6 dBm. The spare MSBs shall be set to the value of the sign bit. + +Field #9 "UPBO reference PSD (UPBOPSD)" contains the parameters to compute the reference PSD that shall be used for the calculation of UPBO as specified in clause 7.2.1.3. One set of UPBOPSD parameters ( $a'$ , $b'$ ) is defined per upstream band. The values of $a'$ and $b'$ are positive and shall be formatted as shown in Table 12-24. + +**Table 12-24 – UPBOPSD descriptor** + +| Octet | Content of field | +|--------------------------------------------|---------------------------------------------------------------------------------------------| +| 1 | Number of US bands | +| 2-4 | bits 0-11: value of $a'$ for US1
bits 12-23: value of $b'$ for US1 | +| 5-7 (if applicable) | bits 0-11: value of $a'$ for US2
bits 12-23: value of $b'$ for US2 | +| etc. | etc. | +| $3 \times n_{us} - 1, 3 \times n_{us} + 1$ | bits 0-11: value of $a'$ for US( $n_{us}$ )
bits 12-23: value of $b'$ for US( $n_{us}$ ) | + +The length of the field is variable and depends on the number of upstream bands exchanged during the ITU-T G.994.1 handshake phase of initialization ( $n_{us}$ ), except US0. Parameters $a'$ and $b'$ shall be coded as 12-bit unsigned integers. The value of $a$ is obtained by multiplying $a'$ by 0.01 and adding it to 40. The range of values for $a$ is between 40 and 80.96. The value of $b$ is obtained by multiplying $b'$ by 0.01. This allows values of $b$ between 0 and 40.96 (see clause 7.2.1.3.2). For those upstream bands in which UPBO shall not be applied, all 12 bits representing values $a'$ and $b'$ shall be set to ZERO (which corresponds to $a = 40, b = 0$ ). + +NOTE 2 – The granularity of 0.01 may be finer than needed for practical purposes, but it has been chosen to be able to transmit the values of $b$ specified in regional VDSL standards referred to in [ITU-T G.993.1]. + +Field #10 "Maximum target total data rate" is the VTU-O's estimate of the maximum downstream total data rate that will be required during the operation of the VTU. The VTU-R may use this information to determine the amount of downstream power cut-back (the downstream PSD ceiling) and the spectrum to be used for downstream transmission (e.g., the highest downstream subcarrier) that is allowed to be used during the channel discovery phase. + +NOTE 3 – The CO should determine an appropriate value of the maximum target total data rate based on the configuration parameters of the bearer channels, such as minimum INP ( $INP\_min_n$ ), maximum delay ( $delay\_max_n$ ), and minimum and maximum net data rates ( $net\_min_n, net\_max_n$ ), provided in the MIB. The knowledge of the minimum INP and maximum delay can be used to estimate the coding overhead $r_n$ , which is the main factor determining the relation between the net data rate assigned for the bearer channel $n$ and the corresponding total data rate: + +$$r_n = \frac{total\_data\_rate_n}{net\_data\_rate_n} = \frac{1}{1 - \frac{2 \times INP\_min_n}{delay\_max_n \times f_s}}$$ + +where $delay\_max_n$ is in milliseconds and $f_s$ is the data symbol rate in ksymbols/s. Knowledge of the net data rates and of the overhead rates of the bearer channels in use allows the VTU-O to make an estimate of the maximum downstream total data rate. + +The field shall be coded as an unsigned integer representing the total data rate as a multiple of 8 kbit/s. + +Field #11 "Downstream maximum SNR margin (MAXSNRMds)" indicates the maximum SNR margin the VTU-R receiver shall try to sustain. The definition and use of this parameter shall be the same as for the parameter "downstream maximum noise margin (MAXSNRMds)" specified in [ITU-T G.997.1]. The field shall be formatted as a 16-bit unsigned integer with LSB weight of 0.1 dB and the valid range between 0 and 31 dB. The special value defined in [ITU-T G.997.1] shall be coded as $FFFF_{16}$ . + +Field #12 "Downstream target SNR margin (TARSNRMds)" indicates the target SNR margin of the VTU-R receiver. The definition and use of this parameter shall be the same as for the parameter "downstream target noise margin (TARSNRMds)" specified in [ITU-T G.997.1]. The format used shall be the same as for Field #11 of the O-SIGNATURE message. + +Field #13 "Downstream transmit window length ( $\beta_{ds}$ )" shall contain the length of the downstream transmit window, ( $\beta_{ds}$ ), expressed in samples at the downstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be coded as an 8-bit integer. + +Field #14 "Downstream cyclic prefix" shall contain the length of the downstream cyclic prefix expressed in samples at the downstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be coded as a 16-bit integer. + +Field #15 "Initial value of timing advance" indicates the initial timing advance and shall be expressed in samples at the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be encoded in a 16-bit field using twos complement format. The special value of $7FFF_{16}$ indicates that the VTU-R shall select the initial setting of the timing advance. + +NOTE 4 – The optimal value of the timing advance is a function of loop length (see clause 10.4.5.3). The initial value should be applicable for most loop lengths. It is suggested to choose an initial value that corresponds to a loop length of 1500 m. This value can be updated later in the initialization. + +Field #16 "Downstream transmitter referred virtual noise PSD (TXREFVNs)" indicates the PSD of the virtual noise in the downstream direction for SNRM\_MODE=2 and SNRM\_MODE=4. For SNRM\_MODE=5, this field indicates the initial value of the downstream SAVN PSD (TXREFSAVNs, see clause 11.4.1.1.6.1.5). This information shall be taken into account when determining the SNR margin (for optional SNRM\_MODE=2, optional SNRM\_MODE=4, and optional SNRM\_MODE=5), which in turn shall be taken into account in determining the possible power cutback during the channel discovery phase, and for performing the bit loading later in initialization. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 32$ . When SNRM\_MODE = 1, the PSD descriptor field shall contain zero breakpoints (only 1 byte with a value of zero). + +NOTE 5 – For SNRM\_MODE=5, the TXREFVNs parameter provided by the CO-MIB may be taken into account by the VTU-O to determine the initial value of TXREFSAVNs (see clause 11.4.1.1.6.1.5). + +Field #17 "SNRM\_MODE" indicates the mode of downstream and upstream SNRM computation as described in clause 11.4.1.1.6. Bits 0 to 3 of the field shall be used to indicate the downstream SNR mode with valid values of $0_{16}$ (Downstream SNRM\_MODE=1, mandatory), $1_{16}$ (Downstream SNRM\_MODE=2, optional), $3_{16}$ (Downstream SNRM\_MODE=4, optional), and $4_{16}$ (Downstream SNRM\_MODE=5, optional). All other values are reserved. Bits 4 to 7 of the field shall be used to indicate the upstream SNR mode with valid values of $0_{16}$ (Upstream SNRM\_MODE=1, mandatory), $1_{16}$ (Upstream SNRM\_MODE=2, optional), $2_{16}$ (Upstream SNRM\_MODE=3, optional), $3_{16}$ (Upstream SNRM\_MODE = 4, optional), and $4_{16}$ (Upstream SNRM\_MODE=5, optional). All other values are reserved. + +Field #18 "Upstream transmitter referred virtual noise PSD (TXREFVNus)" indicates the PSD of the virtual noise in the upstream direction. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 16$ . When SNRM\_MODE = 1, 3, 4 or 5, the PSD descriptor field shall contain zero breakpoints (only 1 byte with a value of zero). + +NOTE 5 – Improper setting of TXREFVN or RXREFVN can interact with the setting of one or more of the following parameters: maximum net data rate, downstream maximum SNR margin, impulse noise protection, and maximum interleaving delay. This interaction can result in high levels of transmit power that can lead to high crosstalk experienced by DSLs on other pairs in the same binder. + +Field #19 "UPBO reference electrical length (UPBOREFEL)" contains the $kl_{0\_REF}$ parameters for the calculation of UPBO according to the optional equalized FEXT UPBO method, as specified in clause 7.2.1.3. One value of the parameter $kl_{0\_REF}$ is defined per upstream band. The values of $kl_{0\_REF}$ shall be formatted as shown in Table 12-25. + +The length of the field is variable and depends on the number of upstream bands ( $n_{us}$ ) exchanged during the ITU-T G.994.1 handshake phase of initialization, except USO. The value shall be coded as a 16-bit unsigned integer with an LSB weight of 0.1 dB. The valid range of values is from 1.8 to 63.0 dB with a 0.1 dB step, and a special value 0. The use of the special value 0 is described in clause 7.2.1.3. + +**Table 12-25 – UPBOREFEL descriptor** + +| Octet | Content of field | +|----------------------------------------|------------------------------------------------------| +| 1 | Number of US bands | +| 2-3 | bits 0-15: value of $kl_{0\_REF}$ for US1 | +| 4-5 (if applicable) | bits 0-15: value of $kl_{0\_REF}$ for US2 | +| ... | | +| $2 \times n_{us}, 2 \times n_{us} + 1$ | bits 0-15: value of $kl_{0\_REF}$ for US( $n_{us}$ ) | + +Field #20 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #21 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +**Table 12-26 – Format of variable length fields #20 and #21** + +| Octet | Name | Format | Description | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|-----------|--------------------------------------------------------------------------------------------------------------| +| 1 | Data length | 1 byte | Number of bytes in the Data field (i.e., N-1). This is the number of bytes following this octet (see Note 1) | +| 2-N | Data | N-1 bytes | N-1 data bytes, with N-1 being equal to the number contained in Octet #1 (see Note 2). | +| NOTE 1 – The number of bytes in the Data field could be zero. In that case, the variable length field consists of a single byte (i.e., N=1) with value 00 16 . | | | | +| NOTE 2 – The N represents the length of the variable length field in bytes. | | | | + +The actual data in the variable length fields #20 and #21 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0016. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field A shall be a single byte with value 0016. + +Field #22 "Alternative Electrical Length Estimation Mode Control" has 2 bytes containing parameters: Alternative Electrical Length Estimation Mode (AELE-MODE), UPBO Electrical Length Minimum Threshold (UPBOELMT), and RXTHRSHDS as shown in Table 12-27, with the parameters specified in clause 7.2.1.3.2.1.2. + +**Table 12-27 – AELE-MODE Control Descriptor** + +| Octet | Content of field | +|-------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Bits 0 to 3: UPBOELEMТ values expressed as 4-bits unsigned integer in percent (Note).
Bits 4 to 5: reserved by ITU and set to 0.
Bits 6 to 7: value AELE-MODE expressed as 2-bit unsigned integer. | +| 2 | RXTHRSHDS parameter coded as an eight bit signed integer $n$ , with valid values being all integers in the range from -64 to 0, representing an offset from -100 dBm/Hz as $RXTHRSHDS = (-100 + n)$ dBm/Hz. | + +NOTE – The only valid value of UPBOELEMТ is 10. Other values are reserved for future use. + +Field #23 is reserved for operation according to Annex X (see clause X.2.2.1.1.1.1). This field shall be set to $00_{16}$ if the selected mode of operation is not according to Annex X, and have a value as defined in Table X.5a otherwise. + +Field #24 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-27a. + +**Table 12-27a – Format of variable length field #24** + +| Octet | Name | Format | Description | +|-------|-------------|-----------|-------------------------------------------------------------------------------------------------------------------| +| 1-2 | Data length | 2 bytes | Number of bytes in the Data field (i.e., N-2). This is the number of bytes following these 2 octets (see Note 1). | +| 3-N | Data | N-2 bytes | N-2 data bytes, with N-2 being equal to the number contained in Octets #1-2 (see Note 2). | + +NOTE 1 – The number of bytes in the Data field could be zero. In that case, the variable length field consists of 2 bytes long (i.e., N=2) with value $0000_{16}$ . + +NOTE 2 – The N represents the length of the variable length field in bytes. + +The actual data in the variable length field #24 is beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of [ITU-T G.993.5] is required. However, support of [ITU-T G.993.5] is not implied or required for compliance with this Recommendation. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field B shall be 2 bytes long with value $0000_{16}$ . + +#### 12.3.3.2.1.2 O-UPDATE + +The full list of parameters carried by the O-UPDATE message is shown in Table 12-28. + +**Table 12-28 – Description of message O-UPDATE** + +| | Field name | Format | +|---|------------------------------------------|------------------| +| 1 | Message descriptor | Message code | +| 2 | Final electrical length | 2 bytes | +| 3 | Updated upstream PSD ceiling (MAXMASKus) | 2 bytes | +| 4 | Highest allowed upstream subcarrier | 2 bytes | +| 5 | Lowest allowed upstream subcarrier | 2 bytes | +| 6 | BLACKOUTus set | Bands descriptor | +| 7 | Timing advance correction | 2 bytes | + +**Table 12-28 – Description of message O-UPDATE** + +| | Field name | Format | +|----|----------------------------------|---------------------| +| 8 | ITU-T G.998.4 parameter field | Variable length | +| 9 | ITU-T G.993.5 parameter field | Variable length | +| 10 | Extended final electrical length | UPBOXFEL descriptor | + +Field #1 "Message descriptor" is a one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Final electrical length" contains the electrical length expressed in dB at 1 MHz (see clause 7.2.1.3.2) that the VTU-R shall use to set its upstream PSD starting from the training phase onward. The value shall be coded as a 16-bit number with the LSB weight of 0.1 dB. The valid range of values is from 0 dB to 128 dB with a 0.1 dB step. This value may be different from the value reported by the VTU-R in R-MSG 1 and shall be used by the VTU-R to determine the UPBOMASK, as specified in clause 7.2.1.3.2. This updated UPBOMASK shall be used to form the upstream MEDLEY reference PSD mask (Field #2 of R-PRM). + +Field #3 "Updated upstream PSD ceiling (MAXMASKus)" indicates the PSD ceiling level of the upstream transmit PSD mask. This field shall be coded the same as Field #7 of O-SIGNATURE. If this level is lower than the upstream PSD ceiling indicated in R-MSG 1, the VTU-R shall apply this new ceiling level to PSDMASKus. Otherwise, the VTU-R may increase the ceiling of the upstream PSD mask up to MAXMASKus. This new ceiling level shall be used to form the upstream MEDLEY reference PSD mask (MREFMASKus). A special value 100016 shall indicate no limit to the upstream PSD ceiling level (under the constraints of the upstream transmit PSD mask). + +Field #4 "Highest allowed upstream subcarrier" contains the index of the highest frequency upstream subcarrier that is allowed to be used by the VTU-R. The format shall be a 16-bit value. The subcarrier index shall be described as 12 bits. The four MSBs of the field shall be set to ZERO. The VTU-R shall not allocate power to subcarriers above the highest allowed upstream subcarrier. + +Field #5 "Lowest allowed upstream subcarrier" contains the index of the lowest-frequency upstream subcarrier that is allowed to be used by the VTU-R. The format shall be a 16-bit value. The subcarrier index shall be described as 12 bits. The four MSBs of the field shall be set to ZERO. The VTU-R shall not allocate power to subcarriers below the lowest allowed upstream subcarrier. + +Field #6 "BLACKOUTus set" contains the BLACKOUT set of subcarriers in the upstream direction. The field shall be formatted as a "bands descriptor" (see Table 12-22) with a maximum number of 16 bands. If there are no blackout subcarriers, the field shall consist of one octet, 0016. + +Field #7 "Timing advance correction" contains the timing advance correction with respect to the currently used timing advance expressed in samples at the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be encoded in a 16-bit field using twos complement format. Positive values shall indicate that the transmitted symbol will be advanced more with respect to the received symbol. + +Field #8 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #9 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 8 and 9 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +Field #10 "Extended final electrical length" contains the electrical length. The UPBOXFEL descriptor has the parameter $kl_0[band]$ for each upstream band expressed in dB at 1 MHz (see Table 12-29, with the parameter specified in clause 7.2.1.3.2.1.2) that the VTU-R shall use to set its upstream PSD starting from the training phase onward. The value shall be coded as a 16-bit number with the LSB weight of 0.1 dB. The valid range of values is from 0 dB to 128 dB with a 0.1 dB step. This value may be different from the value reported by the VTU-R in R-MSG 1 and shall be used by the VTU-R to determine the UPBOMASK, as specified in clause 7.2.1.3.2.3. This updated UPBOMASK shall be used to form the upstream MEDLEY reference PSD mask (Field #2 of R-PRM). + +One value of the parameter $kl_0[band]$ is defined per upstream band. The values of $kl_0$ shall be formatted as shown in Table 12-29. If defined with a valid value, this parameter overrides "Final Electrical Length". + +**Table 12-29 – UPBOXFEL descriptor** + +| Octet | Content of field | +|----------------------------------------|-----------------------------------------------------------| +| 1 | Number of US bands ( $n_{us}$ ) | +| 2-3 | bits 0-15: value of $kl_0[US1]$ for US1 | +| 4-5 (if applicable) | bits 0-15: value of $kl_0[US2]$ for US2 | +| ... | | +| $2 \times n_{us}, 2 \times n_{us} + 1$ | bits 0-15: value of $kl_0[US(n_{us})]$ for US( $n_{us}$ ) | + +### 12.3.3.2.1.3 O-PRM + +O-PRM contains the downstream MEDLEY reference PSD following the modifications proposed in the R-UPDATE message. It also contains the modulation parameters that shall be used in the downstream direction from the beginning of the training phase and requests for the durations of training periods in the training phase. The full list of parameters carried by the O-PRM message is shown in Table 12-30. + +**Table 12-30 – Description of message O-PRM** + +| | Field name | Format | +|----|-----------------------------------------------------|---------------------| +| 1 | Message descriptor | Message code | +| 2 | Downstream MEDLEY reference PSD (MREFPSDds) | PSD descriptor | +| 3 | MEDLEYds set | Bands descriptor | +| 4 | Cyclic extension length | 1 byte | +| 5 | Downstream cyclic prefix length | 2 bytes | +| 6 | Downstream transmit window length ( $\beta_{ds}$ ) | 1 byte | +| 7 | VTU-O IDFT size | 1 byte | +| 8 | Duration of the VTU-O EC training period | 1 byte | +| 9 | Requested duration of the VTU-O TEQ training period | 1 byte | +| 10 | Requested duration of the VTU-R TEQ training period | 1 byte | +| 11 | Requested minimum duration of the periodic signal | 1 byte | +| 12 | Downstream frequency-domain spectrum shaping | Log_tss; descriptor | +| 13 | ITU-T G.998.4 parameter field | Variable length | +| 14 | ITU-T G.993.5 parameter field | Variable length | + +Field #1 "Message descriptor" is a one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Downstream MEDLEY reference PSD (MREFPSDds)" indicates the updated PSD at the U interface, following the request from the VTU-R in R-UPDATE. This PSD shall be used in the downstream direction starting from the beginning of the training phase and for the remainder of initialization. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 48$ . The only valid PSD values obtained by the receiver using the interpolation procedure specified are those for subcarriers that belong to the MEDLEYds set (communicated in Field #3 of O-PRM), excluding the RFI bands communicated during the ITU-T G.994.1 handshake phase. PSD values out of this set shall be ignored by the VTU-R. The values of MREFPSDds shall be at least 3.5 dB below the downstream MEDLEY reference PSD mask (MREFMASKds, see clause 7.2.1), which, excluding the RFI bands, is the minimum of the transmit PSD mask (PSDMASKds, Field #4 of O-SIGNATURE), and the downstream PSD ceiling determined by the VTU-O. Moreover, the valid values of MREFPSDds, either those that are directly communicated or those obtained at the receiver by interpolation, shall not deviate from the downstream transmit PSD, as measured in the reference impedance at the U interface, by more than 1 dB. + +Field #3 "MEDLEYds set" contains the MEDLEY set of subcarriers in the downstream direction. The MEDLEYds subcarriers shall be used starting from the beginning of the training phase. The "bands descriptor" format described in Table 12-22 shall be used. No more than 32 bands shall be specified. + +Field #4 "Cyclic extension length" contains the value of $L_{CE}$ that shall be used starting from the beginning of the training phase. This value may be different from the initial value that was exchanged during the ITU-T G.994.1 handshake phase if the VTUs have indicated that they support a change in CE length. The CE length shall be expressed as $L_{CE} = m \times N/32$ . This field shall encode the value of $m$ as an 8-bit value with valid values from 2 to 16. + +NOTE – The duration of the CE is the same in the upstream and downstream directions. If the IDFT sizes used for both directions are the same, then the number of samples in the CE is also the same. If the IDFT sizes are + +not the same, then the number of samples in the CE in the downstream and upstream directions will differ but can be easily derived using the value of $m$ provided by the VTU-O. + +Field #5 "Downstream cyclic prefix length" contains the value of $L_{CP}$ that shall be applied in the downstream direction starting from the beginning of the training phase. The value shall be expressed in samples of the downstream sampling rate corresponding to the IDFT size communicated in Field #7. The format shall be the same as for Field #14 of the O-SIGNATURE message (Table 12-21). + +Field #6 "Downstream transmit window length ( $\beta_{ds}$ )" contains the length of the transmit window that shall be used in the downstream direction starting from the beginning of the training phase. The value shall be expressed in samples of the downstream sampling rate corresponding to the IDFT size communicated in Field #7. The format shall be the same as for Field #13 of the O-SIGNATURE message (Table 12-21). + +Field #7 "VTU-O IDFT size" indicates the updated size of the IDFT at the VTU-O that shall be used in the downstream direction starting from the beginning of the training phase. This value may be different from the initial value that was exchanged during the ITU-T G.994.1 handshake phase. The value shall be expressed as the IDFT size $2N_{ds}$ . The format shall be an 8-bit field coded as $\log_2(2N_{ds})$ with valid values from 7 to 13. + +Field #8 "Duration of VTU-O EC training period" indicates the duration of the EC training signal the VTU-O shall transmit, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 1024. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #9 "Requested duration of the VTU-O TEQ training period" indicates the minimum duration of the VTU-O TEQ training period that the VTU-O requests, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 16320. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #10 "Requested duration of the VTU-R TEQ training period" indicates the minimum duration of the VTU-R TEQ training period that the VTU-O requests, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 16320. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #11 "Requested minimum duration of the periodic signal" indicates the minimum duration of the R-P-PERIODIC 2 signal that the VTU-O requests, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 2048. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #12 "Downstream frequency-domain spectrum shaping" indicates the $tss_i$ values used by the VTU-O. The field shall be formatted as a "Log\_tss\_i descriptor", shown in Table 12-31, with a maximum number of 64 breakpoints. + +**Table 12-31 – Log\_tss\_i descriptor** + +| Octet | Content of field | +|---------------------|-------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Number of breakpoints (subcarriers) to be described | +| 2-4 | Bits 0-11: Subcarrier index of the first breakpoint
Bits 12-23: $\log\_tss_i$ value of the first breakpoint in steps of 0.1 dB | +| 5-7 (if applicable) | Bits 0-11: Subcarrier index of the second breakpoint
Bits 12-23: $\log\_tss_i$ value of the second breakpoint in steps of 0.1 dB | +| etc. | etc. | + +The first octet of the descriptor shall contain the number of breakpoints being specified. This number can be zero. In that case, there shall be no further octets in the descriptor, and the field shall be interpreted as all $\log\_tss_i = 0$ for all transmitted subcarriers. If the number of breakpoints is not equal + +to zero, each group of three consecutive octets shall describe one breakpoint as a $\log\_tss_i$ value (see clause 10.3.4.3) at a certain subcarrier index. The $tss_i$ values shall be determined by the transmitter such that, with combined frequency domain and time domain spectrum shaping, the downstream PSD at the U interface during the training phase and subsequent initialization phases shall be identical to the value MREFPSDds. + +The first 12 bits (0-11) in the group of three octets shall contain the index of the subcarrier. The last 12 bits (12-23) shall contain the $\log\_tss_i$ value of the subcarrier in dB calculated as specified in clause 10.3.4.3, such that the maximum $\log\_tss_i$ value across all breakpoints shall be 0 dB. Each $\log\_tss_i$ value shall be an integer multiple of -0.1 dB. The receiver shall obtain the $\log\_tss_i$ values for unspecified subcarriers using a linear interpolation between the $\log\_tss_i$ values of the assigned breakpoints as specified in clause 10.3.4.3. + +The VTU-O shall provide non-zero $tss_i$ values for all out-of-band subcarriers with indices from 1 to $t_{DS1\_stop} + 32$ , where $t_{DS1\_stop}$ is the highest-index subcarrier in DS1. The out-of-band $tss_i$ values shall only be used during O-P-TEQ, as described in clause 12.3.4.3.1.4. The out-of-band $tss_i$ values shall be set to ensure that the PSD of O-P-TEQ at the U interface is close to, but below, the relevant stopband limit PSD mask. + +Field #13 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #14 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 13 and 14 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +#### 12.3.3.2.1.4 O-ACK + +O-ACK is a one-byte message that acknowledges correct reception of the R-PRM message. The format of the message shall be as specified in clause 12.2.1, and the payload shall be as specified in Table 12-6. + +#### 12.3.3.2.2 VTU-R messages sent during the channel discovery phase + +##### 12.3.3.2.2.1 R-MSG 1 + +The full list of parameters carried by the R-MSG 1 message is shown in Table 12-32. + +**Table 12-32 – Description of message R-MSG 1** + +| | Field name | Format | +|---|--------------------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | Estimate of electrical length | 2 bytes | +| 3 | Initial upstream PSD ceiling (CDMAXMASKus) | 2 bytes | +| 4 | Channel discovery upstream PSD (CDPSDus) | PSD descriptor | +| 5 | Initialization pilot tones | Tone descriptor | +| 6 | Timing advance | 2 bytes | + +**Table 12-32 – Description of message R-MSG 1** + +| | Field name | Format | +|----|--------------------------------------------------|---------------------| +| 7 | O-P-PILOT settings | 1 byte | +| 8 | Upstream transmit window length ( $\beta_{us}$ ) | 1 byte | +| 9 | Upstream cyclic prefix length | 2 bytes | +| 10 | ITU-T G.998.4 parameter field | Variable length | +| 11 | ITU-T G.993.5 parameter field | Variable length | +| 12 | Extended estimate of electrical length | UPBOXEEL descriptor | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Estimate of electrical length" shall convey the estimate of the electrical length, expressed in dB at 1 MHz (see clause 7.2.1.3.2), as determined by the VTU-R. The value shall be coded as a 16-bit number. The value of the electrical length is obtained by multiplying this 16-bit value by 0.1 dB. The valid range of the electrical length is from 0 dB to 128 dB in 0.1 dB steps. Using this estimate of the electrical length, the VTU-R shall derive the upstream power back-off (UPBO) as described in clause 7.2.1.3. When using the alternative electrical length estimation method (ELE-M1) this parameter contains the value ELEDS. + +Field #3 "Initial upstream PSD ceiling (CDMAXMASKus)" indicates the PSD level that is used to impose a ceiling on the upstream transmit PSD mask (after UPBO is performed) to form the upstream PSD mask for the signals transmitted during the channel discovery phase. The upstream channel discovery PSD (CDPSDus, see Field #4) is derived using the value of CDMAXMASKus. This field shall be coded the same as Field #7 of O-SIGNATURE. + +Field #4 "Channel discovery upstream PSD (CDPSDus)" indicates the PSD at the U interface transmitted in the upstream direction during the channel discovery phase. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 32$ . The only valid PSD values obtained by the receiver using the interpolation procedure specified are those for subcarriers that belong to the SUPPORTEDCARRIERsus set, excluding the RFI bands communicated during the ITU-T G.994.1 handshake phase. PSD values out of this set shall be ignored by the receiver. The CDPSDus values shall be at least 3.5 dB below the upstream transmit PSD mask (Field #5 of O-SIGNATURE), and at least 3.5 dB below the initial upstream PSD ceiling (Field #3 of R-MSG 1), and at least 3.5 dB below the UPBOMASK that corresponds to the electrical length value defined in Field #2. Moreover, the valid values of CDPSDus, either those which are directly communicated or those obtained at the receiver by interpolation, shall not deviate from the actual value of the transmit PSD, as measured in the reference impedance at the U interface, by more than 1 dB. + +Field #5 "Initialization pilot tones" indicates the selection of pilot tones by the VTU-R for timing recovery during the O-P-PILOT 1, O-P-PILOT 2, O-P-PILOT 3 and O-P-ECT stages. This information shall be used by the VTU-O during the lineprobe stage (if selected), and during the TEQ and echo canceller training stages of the training phase. The field shall be formatted as shown in Table 12-33. The total number of initialization pilot tones shall not exceed 16. + +**Table 12-33 – Tone descriptor** + +| Octet | Content of field | +|---------------------|-----------------------------------------------------------| +| 1 | Number of tones | +| 2-4 | Bits 0-11: index of tone 1
Bits 12-23: index of tone 2 | +| 5-7 (if applicable) | Bits 0-11: index of tone 3
Bits 12-23: index of tone 4 | +| etc. | etc. | + +The first octet of the tone descriptor shall contain the number of pilot tones selected by the VTU-R. If this number is zero, there shall be no further octets in the descriptor. If the number of tones is not equal to zero, each group of three consecutive octets in the descriptor shall describe the location of two pilot tones. + +The first 12 bits (0-11) and the last 12 bits (12-23) in each group of three octets shall contain the indices of two tones. For example, a field value 40020016 means tone 20016 = 512 and tone 40016 = 1024. If the number of pilot tones is odd, the last 12 bits in the field shall be set to ZERO. + +Field #6 "Timing advance" indicates the timing advance selected by the VTU-R (which is either the initial value conveyed by the O-SIGNATURE message or a vendor-discretionary setting if no initial value was set by the VTU-O). It shall be expressed in samples at the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be encoded in a 16-bit field using twos complement format. + +Field #7 "O-P-PILOT settings" indicates the setting of pilot tone power in O-P-PILOT signals during various stages. The format is one byte with the following encoding: + +- the first MSB indicates whether the selected pilot tone(s) shall be allocated power in O-P-PILOT 1 during the channel discovery phase (1=ON, 0=OFF); +- the second and third MSBS indicate, respectively, whether the selected pilot tone(s) shall be allocated power in O-P-PILOT 2 and O-P-PILOT 3 during the training phase (1=ON, 0=OFF); +- other bits shall be set to ZERO. + +Field #8 "Upstream transmit window length ( $\beta_{us}$ )" contains the length of the transmit window that shall be used in the upstream direction during the channel discovery phase. The value shall be expressed in the samples of the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The format shall be the same as for Field #13 of the O-SIGNATURE message (Table 12-21). + +Field #9 "Upstream cyclic prefix length" contains the length of the upstream cyclic prefix expressed in samples of the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be coded as a 16-bit unsigned integer. + +Field #10 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #11 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 10 and 11 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +Field #12 "Extended estimated electrical length" contains the estimated electrical length. The UPBOXEEL descriptor has the parameter *ELE[band]* in dB for each downstream band (see Table 12-34, with the parameter specified in clause 7.2.1.3.2.1.2). The value shall be coded as a 16-bit number with the LSB weight of 0.1 dB. The valid range of values is from 0 dB to 128 dB with a 0.1 dB step. + +**Table 12-34 – UPBOXEEL descriptor** + +| Octet | Content of field | +|----------------------------------------|----------------------------------------------------| +| 1 | Number of DS bands ( nds ) | +| 2-3 | bits 0-15: value of ELE[DS1] | +| 4-5 (if applicable) | bits 0-15: value of ELE[DS2] | +| ... | | +| $2 \times n_{ds}, 2 \times n_{ds} + 1$ | bits 0-15: value of ELE[DS(nds)] | + +#### 12.3.3.2.2.2 R-UPDATE + +The R-UPDATE message is a request to modify the downstream PSD. The full list of parameters carried by the R-UPDATE message is shown in Table 12-35. + +**Table 12-35 – Description of message R-UPDATE** + +| | Field name | Format | +|---|--------------------------------------------|------------------| +| 1 | Message descriptor | Message code | +| 2 | Updated downstream PSD ceiling (MAXMASKds) | 2 bytes | +| 3 | Proposed highest downstream subcarrier | 2 bytes | +| 4 | Proposed lowest downstream subcarrier | 2 bytes | +| 5 | BLACKOUTds set | Bands descriptor | +| 6 | Suggested cyclic extension length | 1 byte | +| 7 | ITU-T G.998.4 parameter field | Variable length | +| 8 | ITU-T G.993.5 parameter field | Variable length | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Updated downstream PSD ceiling (MAXMASKds)" indicates the PSD ceiling level of the downstream transmit PSD mask. This field shall be coded the same as Field #7 of O-SIGNATURE. If this level is lower than the downstream PSD ceiling indicated in O-SIGNATURE, the VTU-O shall apply this new ceiling level to PSDMASKds. Otherwise, the VTU-O may increase the ceiling of the downstream PSD mask up to MAXMASKds. This new ceiling level shall be used to form the downstream MEDLEY reference PSD mask (MREFMASKds). A special value $1000_{16}$ shall indicate that there is no limit on the downstream PSD ceiling level (under the constraints of the downstream transmit PSD mask). + +Field #3 "Proposed highest downstream subcarrier" contains an estimate by the VTU-R of the highest-index downstream subcarrier that can be loaded with data bits. The format shall be the same + +as for Field #4 of the O-UPDATE message. The VTU-O may transmit subcarriers with indices higher than this value, as long as those subcarriers are in the SUPPORTEDCARRIERSds set. + +Field #4 "Proposed lowest downstream subcarrier" contains an estimate by the VTU-R of the lowest-index downstream subcarrier that can be loaded with data bits. The format shall be the same as for Field #5 of the O-UPDATE message. The VTU-O may transmit subcarriers with indices lower than this value, as long as those subcarriers are in the SUPPORTEDCARRIERSus set. + +Field #5 "BLACKOUTds set" contains the BLACKOUT set of subcarriers in the downstream direction. The field shall be formatted as a "bands descriptor" (see Table 12-22), with a maximum number of 16 bands. If there are no blackout subcarriers, the field shall consist of one octet, 0016. + +Field #6 "Suggested cyclic extension length" contains the value of the CE length suggested by the VTU-R. This value may be different from the initial value exchanged during the ITU-T G.994.1 handshake phase if both VTUs support a change in CE length. The final CE length shall be decided by the VTU-O (see O-PRM message in clause 12.3.3.2.1.3). The format shall be the same as for Field #4 of the O-PRM message (Table 12-30). + +Field #7 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #8 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 7 and 8 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +#### 12.3.3.2.2.3 R-PRM + +The R-PRM message is sent in response to the O-PRM message. It contains the upstream MEDLEY reference PSD following the modifications proposed in the O-UPDATE message. It also contains the modulation parameters that shall be used in the upstream direction from the beginning of the training phase and requests for the durations of training periods in the training phase. The full list of parameters carried by the R-PRM message is shown in Table 12-36. + +**Table 12-36 – Description of message R-PRM** + +| | Field name | Format | +|---|-----------------------------------------------------|------------------| +| 1 | Message descriptor | Message code | +| 2 | Upstream MEDLEY reference PSD (MREFPSDus) | PSD descriptor | +| 3 | MEDLEYus set | Bands descriptor | +| 4 | Upstream cyclic prefix length | 2 bytes | +| 5 | Upstream transmit window length ( $\beta_{us}$ ) | 1 byte | +| 6 | VTU-R IDFT size | 1 byte | +| 7 | Duration of the VTU-R EC training period | 1 byte | +| 8 | Requested duration of the VTU-R TEQ training period | 1 byte | +| 9 | Requested duration of the VTU-O TEQ training period | 1 byte | + +**Table 12-36 – Description of message R-PRM** + +| | Field name | Format | +|----|-----------------------------------------------------------------------|---------------------------------| +| 10 | Requested minimum duration of the periodic signal | 1 byte | +| 11 | Minimum duration of the R-P-TRAINING 1 signal ( $T_{MIN-R-P-Train}$ ) | 1 byte | +| 12 | Upstream frequency-domain spectrum shaping | Log_tss i descriptor | +| 13 | ITU-T G.998.4 parameter field | Variable length | +| 14 | ITU-T G.993.5 parameter field | Variable length | + +Field #1 "Message descriptor" is a one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Upstream MEDLEY reference PSD (MREFPSDus)" indicates the updated PSD at the U interface following the request from the VTU-O in O-UPDATE. This PSD shall be used in the upstream direction from the beginning of the training phase and for the remainder of initialization. The "PSD descriptor" format specified in Table 12-23 shall be used, and the number of subcarriers being described shall be limited to $\leq 32$ . The only valid PSD values obtained by the receiver using the interpolation procedure specified are those for the subcarriers that belong to the MEDLEYus set (communicated in Field #3), excluding the RFI bands communicated during the ITU-T G.994.1 handshake phase. PSD values out of this set shall be ignored by the VTU-O. The values of MREFPSDus shall be at least 3.5 dB below the upstream MEDLEY reference PSD mask (MREFMASKus, see clause 7.2.1) which, excluding the RFI bands, is the minimum of the transmit PSD mask (PSDMASKus, Field #5 of O-SIGNATURE), the UPBOMASK determined by the VTU-R (which corresponds to the electrical length value defined in Field #2 of O-UPDATE), and the upstream PSD ceiling determined by the VTU-R. Moreover, the valid values of MREFPSDus, either those that are directly communicated or those obtained at the receiver by interpolation, shall not deviate from the upstream transmit PSD, as measured in the reference impedance at the U interface, by more than 1 dB. + +Field #3 "MEDLEYus set" contains the MEDLEY set of subcarriers in the upstream direction. The MEDLEYus subcarriers shall be used starting from the beginning of the training phase. The "bands descriptor" format described in Table 12-22 shall be used. No more than 32 bands shall be specified. + +Field #4 "Upstream cyclic prefix length" contains the value of the cyclic prefix that shall be applied in the upstream direction starting from the beginning of the training phase. The value shall be expressed in samples of the upstream sampling rate corresponding to the IDFT size communicated in Field #6. The format of the selected cyclic prefix length shall be the same as for Field #14 of the O-SIGNATURE message (Table 12-21). + +NOTE – The value of the CE length used in the calculation of the upstream cyclic prefix length is the value communicated in O-PRM, not the one sent in R-UPDATE. + +Field #5 "Upstream transmit window length ( $\beta_{us}$ )" contains the length of the transmit window that shall be used in the upstream direction starting from the beginning of the training phase. The value shall be expressed in samples of the upstream sampling rate corresponding to the IDFT size communicated in Field #6. The format shall be the same as for Field #13 of the O-SIGNATURE message (Table 12-21). + +Field #6 "VTU-R IDFT size" communicates the IDFT size, $2N_{us}$ , that shall be used by the VTU-R starting from the beginning of the training phase. The format shall be an 8-bit field coded as $\log_2(2N_{us})$ , with valid values from 6 to 13. This value may be different from the initial value that was exchanged during the ITU-T G.994.1 handshake phase. + +Field #7 "Duration of VTU-R EC training period" indicates the duration of the VTU-R EC training signal that the VTU-R shall transmit, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 1024. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #8 "Requested duration of the VTU-R TEQ training period" indicates the minimum duration of the VTU-R TEQ training period that the VTU-R requests, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 16320. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #9 "Requested duration of the VTU-O TEQ training period" indicates the minimum duration of the VTU-O TEQ training period that the VTU-R requests, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 16320. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #10 "Requested minimum duration of the periodic signal" indicates the minimum duration of the *O-P-PERIODIC 2* signal the VTU-R requests, expressed in DMT symbols. It shall be an integer multiple of 64 in the range from 0 to 2048. The duration divided by 64 shall be encoded as an 8-bit value. + +Field #11 "Minimum duration of the R-P-TRAINING 1 signal ( $T_{MIN-R-P-Train}$ )" indicates the minimum duration of the *R-P-TRAINING 1* signal that the VTU-R shall transmit. The value, $T_{MIN-R-P-Train}$ , shall be expressed in DMT symbols. The duration shall be an integer multiple of 64 symbols. The integer multiple (i.e., the duration divided by 64) shall be encoded as an 8-bit value. + +Field #12: "Upstream frequency-domain spectrum shaping" indicates the updated $tss_{i}$ values used by the VTU-R. The field shall be formatted as a "Log\_ $tss_{i}$ descriptor" as shown in Table 12-31. + +The VTU-R shall provide non-zero $tss_{i}$ values for all out-of-band subcarriers with indices from 1 to $t_{US0\_stop} + 32$ , where $t_{US0\_stop}$ is the highest-index subcarrier in US0. The out-of-band $tss_{i}$ values (virtual values, since no out-of-band subcarriers are transmitted during channel discovery) shall only be used during *R-P-TEQ*, as described in clause 12.3.4.3.2.4. The out-of-band $tss_{i}$ values shall be set to ensure that the PSD of *R-P-TEQ* at the U interface is close to, but below, the relevant stopband Limit PSD mask. + +Field #13 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #14 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 13 and 14 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +### 12.3.3.3 Signals transmitted during the channel discovery phase + +All signals transmitted during the channel discovery phase shall use only subcarriers from the SUPPORTEDCARRIERds set in the downstream direction and subcarriers from the SUPPORTEDCARRIERus set in the upstream direction. + +The transmit PSD of all downstream signals with non-zero output power shall comply with the downstream transmit PSD mask (PSDMASKds), in both the passband and the stopbands, capped at the level of the initial downstream PSD ceiling (Field #7 of O-SIGNATURE). The downstream PSD + +shall not exceed $-80$ dBm/Hz in any RFI bands that were defined during the ITU-T G.994.1 handshake phase. The values of CE and $2N_{ds}$ shall be as defined during the ITU-T G.994.1 handshake phase. The values of $\beta_{ds}$ and the cyclic prefix length shall be as communicated in Fields #13 and #14 of O-SIGNATURE, respectively. + +The transmit PSD of all upstream signals with non-zero output power shall comply with the upstream transmit PSD mask (PSDMASKus), in both the passband and the stopbands, capped at the level of the initial upstream PSD ceiling (Field #3 of R-MSG 1). The upstream PSD shall comply with UPBO requirements specified in clause 7.2.1.3 and shall not exceed $-80$ dBm/Hz in any RFI bands that were defined during the ITU-T G.994.1 handshake phase. The values of CE and $2N_{us}$ shall be as defined during the ITU-T G.994.1 handshake phase. The values of $\beta_{us}$ and timing advance shall be as communicated in Field #8 and Field #6 of R-MSG 1, respectively. The cyclic prefix length shall be as communicated in Field #9 of R-MSG 1. + +### 12.3.3.3.1 Signals transmitted by the VTU-O + +#### 12.3.3.3.1.1 O-P-QUIET 1 + +O-P-QUIET 1 shall provide a zero output voltage at the U reference point. All subcarriers shall be allocated zero power. + +The duration of O-P-QUIET 1 is variable between 512 and 1 024 symbols. Its duration is at the discretion of the VTU-O. + +#### 12.3.3.3.1.2 O-P-CHANNEL DISCOVERY 1 + +O-P-CHANNEL DISCOVERY 1 is a signal that allows the VTU-R to synchronize and to measure the attenuation of the channel. During transmission of O-P-CHANNEL DISCOVERY 1, the SOC is in its active state. + +The duration of O-P-CHANNEL DISCOVERY 1 is variable. O-P-CHANNEL DISCOVERY 1 is terminated by transmission of O-P-SYNCHRO 1. + +O-P-CHANNEL DISCOVERY 1 shall be composed of all subcarriers in SUPPORTEDCARRIERsd modulated by 4-QAM. Each DMT symbol of O-P-CHANNEL DISCOVERY 1 shall carry one byte of information. The mapping of bits to subcarriers shall be as summarized in Table 12-37. + +**Table 12-37 – Bit mapping for O-P-CHANNEL DISCOVERY 1** + +| Subcarrier index | Constellation point | +|-------------------------------|--------------------------| +| Even | 00 | +| 1, 11, 21, ..., $10n+1$ , ... | SOC message bits 0 and 1 | +| 3, 13, 23, ..., $10n+3$ , ... | SOC message bits 2 and 3 | +| 5, 15, 25, ..., $10n+5$ , ... | SOC message bits 4 and 5 | +| 7, 17, 27, ..., $10n+7$ , ... | SOC message bits 6 and 7 | +| 9, 19, 29, ..., $10n+9$ , ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1,b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of the subcarriers from the SUPPORTEDCARRIERs set of the O-P-CHANNEL DISCOVERY 1 signal shall be equal to CDPSDds (communicated in Field #6 of O-SIGNATURE). + +#### **12.3.3.3.1.3 O-P-SYNCHRO 1** + +O-P-SYNCHRO 1 is a signal that provides an exact time marker for transitions from O-P-CHANNEL DISCOVERY 1 to either O-P-QUIET 2/O-P-PILOT 1 or O-P-PERIODIC 1. During transmission of O-P-SYNCHRO 1, the SOC is in its inactive state. + +The duration of O-P-SYNCHRO 1 is 15 DMT symbols. + +O-P-SYNCHRO 1 shall use all subcarriers in the SUPPORTEDCARRIERs set modulated by 4-QAM. The value 11 shall be mapped to all of the SUPPORTEDCARRIERs subcarriers for the first 5 and the last 5 DMT symbols. The value 00 shall be mapped to all SUPPORTEDCARRIERs subcarriers for the middle 5 DMT symbols. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of the SUPPORTEDCARRIERs subcarriers in O-P-SYNCHRO 1 shall be the same as for O-P-CHANNEL DISCOVERY 1. + +#### **12.3.3.3.1.4 O-P-PILOT 1** + +The O-P-PILOT 1 signal is intended to allow the VTU-R to maintain loop timing during the lineprobe stage. During the transmission of O-P-PILOT 1, the SOC is in its inactive state. + +The duration of O-P-PILOT 1 is 640 DMT symbols with CE. + +O-P-PILOT 1 consists only of the pilot tones that were chosen by the VTU-R and communicated to the VTU-O in Field #5 of R-MSG 1. A value of 00 shall be mapped to all pilot tones with 4-QAM modulation during every symbol of O-P-PILOT 1. + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of O-P-PILOT 1 shall comply with the downstream transmit PSD mask (PSDMASKds) capped at the level of the initial downstream PSD ceiling communicated in Field #7 of O-SIGNATURE. The transmit power of the pilot tones shall be set to 0 if the first MSB of the O-P-PILOT settings field of R-MSG 1 is set to ZERO. + +#### **12.3.3.3.1.5 O-P-QUIET 2** + +O-P-QUIET 2 is identical to O-P-QUIET 1 except that its duration shall be a fixed 640 DMT symbols with CE. + +#### **12.3.3.3.1.6 O-P-PERIODIC 1** + +O-P-PERIODIC 1 is a periodic signal intended to allow both VTUs to make accurate SNR measurements. During transmission of O-P-PERIODIC 1, the SOC is in its inactive state. + +The duration of O-P-PERIODIC 1 shall be 2048 DMT symbols with CE. + +O-P-PERIODIC 1 shall be composed of all subcarriers in the SUPPORTEDCARRIERs set. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to all subcarriers in the SUPPORTEDCARRIERs set. The constellation points on all subcarriers shall be rotated based on + +the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +O-P-PERIODIC 1 shall be constructed as described in clause 12.3.6.1. + +The transmit PSD of the SUPPORTEDCARRIERs subcarriers in O-P-PERIODIC 1 shall be the same as for O-P-CHANNEL DISCOVERY 1. + +#### **12.3.3.3.1.7 O-P-SYNCHRO 2** + +O-P-SYNCHRO 2 is a signal that provides an exact time marker for transitions from O-P-PERIODIC 1 to O-P-CHANNEL DISCOVERY 2. During transmission of O-P-SYNCHRO 2, the SOC is in its inactive state. + +O-P-SYNCHRO 2 shall be identical to O-P-SYNCHRO 1. + +#### **12.3.3.3.1.8 O-P-CHANNEL DISCOVERY 2** + +O-P-CHANNEL DISCOVERY 2 allows the VTU-O to send updated modulation parameters as well as information needed for the training phase (such as signal durations). During transmission of O-P-CHANNEL DISCOVERY 2, the SOC is in its active state. + +The duration of O-P-CHANNEL DISCOVERY 2 is variable. O-P-CHANNEL DISCOVERY 2 is terminated by the transmission of O-P-SYNCHRO 3. + +The symbols of O-P-CHANNEL DISCOVERY 2 shall be constructed in the same manner as the symbols of O-P-CHANNEL DISCOVERY 1 (see clause 12.3.3.3.1.2). + +The transmit PSD of the subcarriers from the SUPPORTEDCARRIERs set of the O-P-CHANNEL DISCOVERY 2 signal shall be equal to CDPSDd (communicated in Field #6 of O-SIGNATURE). + +#### **12.3.3.3.1.9 O-P-SYNCHRO 3** + +O-P-SYNCHRO 3 is a signal that provides an exact time marker for transitions from O-P-CHANNEL DISCOVERY 2 to O-P-TRAINING 1 (training phase). + +O-P-SYNCHRO 3 shall be identical to O-P-SYNCHRO 1. + +### **12.3.3.3.2 Signals transmitted by the VTU-R** + +#### **12.3.3.3.2.1 R-P-QUIET 1** + +R-P-QUIET 1 shall provide a zero output voltage at the U reference point. All subcarriers shall be allocated zero power. The duration of R-P-QUIET 1 is variable. Its duration is at the discretion of the VTU-R. + +#### **12.3.3.3.2.2 R-P-CHANNEL DISCOVERY 1** + +R-P-CHANNEL DISCOVERY 1 is a signal used by the VTU-R to send information about the upstream PSD, timing advance, and its selection of pilot tones (if any). During transmission of R-P-CHANNEL DISCOVERY 1, the SOC is in its active state. + +The duration of R-P-CHANNEL DISCOVERY 1 is variable. R-P-CHANNEL DISCOVERY 1 is terminated by transmission of R-P-SYNCHRO 1. + +R-P-CHANNEL DISCOVERY 1 shall be composed of all subcarriers in SUPPORTEDCARRIERs modulated by 4-QAM. Each DMT symbol of R-P-CHANNEL DISCOVERY 1 shall carry one byte of information. The mapping of bits to subcarriers is summarized in Table 12-38. + +**Table 12-38 – Bit mapping for R-P-CHANNEL DISCOVERY 1** + +| Subcarrier index | Constellation point | +|-------------------------------|--------------------------| +| Even | 00 | +| 1, 11, 21, ..., $10n+1$ , ... | SOC message bits 0 and 1 | +| 3, 13, 23, ..., $10n+3$ , ... | SOC message bits 2 and 3 | +| 5, 15, 25, ..., $10n+5$ , ... | SOC message bits 4 and 5 | +| 7, 17, 27, ..., $10n+7$ , ... | SOC message bits 6 and 7 | +| 9, 19, 29, ..., $10n+9$ , ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1,b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +The constellation points of all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{us}$ . + +The transmit PSD of the subcarriers from the SUPPORTEDCARRIERus set of the R-P-CHANNEL DISCOVERY 1 signal shall be equal to CDPSDus (communicated in Field #4 of R-MSG 1). + +#### 12.3.3.3.2.3 R-P-SYNCHRO 1 + +R-P-SYNCHRO 1 is a signal that provides an exact time marker for transitions from R-P-CHANNEL DISCOVERY 1 to R-P-PERIODIC 1 or R-P-LINEPROBE if requested during the G.994.1 handshake phase. During transmission of R-P-SYNCHRO 1, the SOC is in its inactive state. + +The duration of R-P-SYNCHRO 1 is 15 DMT symbols. + +R-P-SYNCHRO 1 shall use all subcarriers in the SUPPORTEDCARRIERus set modulated by 4-QAM. The value 11 shall be mapped to all SUPPORTEDCARRIERus subcarriers for the first 5 and the last 5 DMT symbols. The value 00 shall be mapped to all of the SUPPORTEDCARRIERus subcarriers for the middle 5 DMT symbols. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{us}$ . + +The transmit PSD of the SUPPORTEDCARRIERus subcarriers in R-P-SYNCHRO 1 shall be the same as for R-P-CHANNEL DISCOVERY 1. + +#### 12.3.3.3.2.4 R-P-LINEPROBE + +R-P-LINEPROBE is a vendor-discretionary signal that allows the VTU-R to perform line probing. During transmission of R-P-LINEPROBE, the SOC is in its inactive state. + +The duration of R-P-LINEPROBE is 512 DMT symbols with CE. + +The transmit PSD of R-P-LINEPROBE shall respect PSDMASKus, in both the passband and the stopbands, capped at the level of the initial upstream PSD ceiling (Field #3 of R-MSG 1). The PSD of R-P-LINEPROBE shall comply with UPBO requirements specified in clause 7.2.1.3 and shall not exceed $-80$ dBm/Hz in any RFI bands that were defined during the ITU-T G.994.1 handshake phase. + +#### **12.3.3.3.2.5 R-P-PERIODIC 1** + +R-P-PERIODIC 1 is a periodic signal intended to allow both VTUs to make accurate SNR measurements. During transmission of R-P-PERIODIC 1, the SOC is in its inactive state. + +The duration of R-P-PERIODIC shall be 2048 DMT symbols with CE. + +R-P-PERIODIC 1 shall be composed of all subcarriers in the SUPPORTEDCARRIERSus set. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to all subcarriers in the SUPPORTEDCARRIERSus set. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +R-P-PERIODIC 1 shall be constructed as described in clause 12.3.6.1. + +The transmit PSD of the SUPPORTEDCARRIERSus subcarriers in R-P-PERIODIC 1 shall be the same as for R-P-CHANNEL DISCOVERY 1. + +#### **12.3.3.3.2.6 R-P-SYNCHRO 2** + +R-P-SYNCHRO 2 is a signal that provides an exact time marker for transitions from R-P-PERIODIC 1 to R-P-CHANNEL DISCOVERY 2. During transmission of R-P-SYNCHRO 2, the SOC is in its inactive state. + +R-P-SYNCHRO 2 shall be identical to R-P-SYNCHRO 1. + +#### **12.3.3.3.2.7 R-P-CHANNEL DISCOVERY 2** + +R-P-CHANNEL DISCOVERY 2 allows the VTU-R to request modifications to the downstream transmit signal, to send updated modulation parameters, and to send information needed for the training phase (such as signal durations). During transmission of R-P-CHANNEL DISCOVERY 2, the SOC is in its active state. + +The duration of R-P-CHANNEL DISCOVERY 2 is variable. R-P-CHANNEL DISCOVERY 2 is terminated by the transmission of R-P-SYNCHRO 3. + +The symbols of R-P-CHANNEL DISCOVERY 2 shall be constructed in the same manner as the symbols of R-P-CHANNEL DISCOVERY 1 (see clause 12.3.3.3.2.2). + +The transmit PSD of the subcarriers from the SUPPORTEDCARRIERSus set of the R-P-CHANNEL DISCOVERY 2 signal shall be equal to CDPSDus (communicated in Field #4 of R-MSG 1). + +#### **12.3.3.3.2.8 R-P-SYNCHRO 3** + +R-P-SYNCHRO 3 is a signal that provides an exact time marker for transitions from R-P-CHANNEL DISCOVERY 2 to R-P-QUIET 2 (training phase). + +R-P-SYNCHRO 3 shall be identical to R-P-SYNCHRO 1. + +### **12.3.4 Training phase** + +#### **12.3.4.1 Overview** + +During the training phase, the VTUs may train their TEQ and echo canceller (EC). In the case that a TEQ or EC or both are not required, the corresponding stages may be shortened to accelerate completion of the initialization procedure. Also, the value of timing advance may be adjusted during this phase. + +Figure 12-8 presents the timing diagram for the stages of the training phase. It gives an overview of the sequence of signals transmitted and SOC messages sent by the VTU-O and VTU-R during the training phase. The two inner columns show the sequences of signals that are transmitted (see clause 12.3.4.3). The two outer columns show the messages that are sent over the SOC (see clause 12.3.4.2). The shaded areas correspond to periods of time when the SOC is in its inactive state. + +![Timing diagram for the stages of the training phase showing Downstream and Upstream signals and SOC messages over time.](b35608e925cb6a7c0aa0db30d2db9d66_img.jpg) + +The diagram illustrates the timing of the training phase between a Downstream and an Upstream entity. The vertical axis represents time, with the main training duration labeled 'TRAINING phase (VTU-O)' on the left and 'TRAINING phase (VTU-R)' on the right. + +**Downstream (Left Side):** + +- SOC Messages:** + - Initial state: Gray block. + - First active state: O-IDLE. + - Second active state: O-TA\_UPDATE. + - Third active state: O-IDLE. + - Final state: Gray block. +- Signals:** + - Initial state: Gray block. + - First active state: O-P-TRAINING 1. + - Second active state: O-P-SYNCHRO 4. + - Third active state: O-P-PILOT 2. + - Fourth active state: O-P-ECT. + - Fifth active state: O-P-TEQ. + - Sixth active state: O-P-PILOT 3. + - Seventh active state: O-P-PERIODIC 2. + - Eighth active state: Gray block. + - Ninth active state: O-P-TRAINING 2. + - Tenth active state: Gray block. + - Eleventh active state: O-P-SYNCHRO 5. + - Final state: Gray block. + +**Upstream (Right Side):** + +- Signals:** + - Initial state: R-P-QUIET 2. + - First active state: R-P-TRAINING 1. + - Second active state: R-P-SYNCHRO 4. + - Third active state: R-P-TEQ. + - Fourth active state: R-P-QUIET 3. + - Fifth active state: R-P-ECT. + - Sixth active state: R-P-PERIODIC 2. + - Seventh active state: Gray block. + - Eighth active state: R-P-TRAINING 2. + - Ninth active state: Gray block. + - Tenth active state: R-P-SYNCHRO 5. + - Final state: Gray block. +- SOC Messages:** + - Initial state: Gray block. + - First active state: R-IDLE. + - Second active state: R-TA\_UPDATE. + - Third active state: R-IDLE. + - Fourth active state: R-ACK. + - Fifth active state: R-IDLE. + - Final state: Gray block. + +Horizontal dashed lines connect corresponding states between the Downstream and Upstream entities to show synchronization. + +Timing diagram for the stages of the training phase showing Downstream and Upstream signals and SOC messages over time. + +G.993.2(15)\_F12-8 + +Figure 12-8 – Timing diagram for the stages of the training phase + +NOTE 1 – In the exchange of the SOC messages identified in Figure 12-8, the rules of the communication protocol of clause 12.2.2 apply. Some messages sent in the SOC may require segmentation; although this is not shown in Figure 12-8, the segmented message elements and their corresponding acknowledgements are sent via the SOC per the communication protocol of clause 12.2.2. + +At the start of the training phase, the VTU-O shall transmit O-P-TRAINING 1, and the VTU-R shall be silent (R-P-QUIET 2). This time may be used by the VTU-R to recover timing or symbol boundaries in case one or more of the modulation parameters (CE length, IDFT size, etc.) was changed at the completion of the channel discovery phase. + +After not more than 4 096 symbols, the VTU-R shall transition from R-P-QUIET 2 to transmitting R-P-TRAINING 1. During the period that R-P-TRAINING 1 is transmitted, both VTUs can re-adjust their AGC settings to adapt to changes in the transmit PSD at the completion of the channel discovery phase. After the VTU-O receives at least $T_{MIN-R-P-Train}$ R-P-TRAINING 1 symbols (Field #11 of R-PRM, see clause 12.3.3.2.2.3), it shall transmit O-P-SYNCHRO 4 to indicate the start of the TEQ and EC training stages. After detecting O-P-SYNCHRO 4, the VTU-R shall respond within a time period between 48 and 64 symbols by transmitting R-P-SYNCHRO 4. + +The durations of the TEQ training signals, the EC training signals, and the periodic signal transmitted after TEQ and EC training are determined from the values requested by the VTU-O and VTU-R during the channel discovery phase. They shall be defined as: + +- $T_{VTU-O\_TEQ}$ : duration of the VTU-O TEQ training, equal to the greater of the values requested by the VTU-O in Field # 9 of O-PRM and by the VTU-R in Field #9 of R-PRM; +- $T_{VTU-R\_TEQ}$ : duration of the VTU-R TEQ training, equal to the greater of the values requested by the VTU-O in Field #10 of O-PRM and by the VTU-R in Field #8 of R-PRM; +- $T_{VTU-O\_EC}$ : duration of the VTU-O EC training, equal to the value communicated by the VTU-O in Field #8 of O-PRM; +- $T_{VTU-R\_EC}$ : duration of the VTU-R EC training, equal to the value communicated by the VTU-R in Field #7 of R-PRM; and +- $T_{Periodic}$ : duration of the O-P-PERIODIC 2 and R-P-PERIODIC 2 signals following TEQ and EC training, equal to the greater of the values requested by the VTU-O in Field #11 of O-PRM and by the VTU-R in Field #10 of R-PRM. + +The VTUs shall determine when to transition from one stage to the next by counting the number of symbols transmitted during each stage. + +Immediately after transmission of O-P-SYNCHRO 4, the VTU-O shall transmit O-P-PILOT 2 and shall continue transmitting O-P-PILOT 2 for $T_{VTU-O\_TEQ}$ symbols. Immediately after transmission of R-P-SYNCHRO 4, the VTU-R shall transmit R-P-TEQ for $T_{VTU-O\_TEQ}$ symbols. During this stage, the VTU-O may train its TEQ. + +NOTE 2 – It is expected that the timing recovery at the VTU-R will be stable during the last 512 symbols of R-P-TEQ transmission. + +Immediately after all $T_{VTU-O\_TEQ}$ symbols of O-P-PILOT 2 have been transmitted, the VTU-O shall transmit O-P-ECT for $T_{VTU-O\_EC}$ symbols. During transmission of O-P-ECT, the VTU-O may train its echo canceller. + +After all $T_{VTU-O\_EC}$ symbols of O-P-ECT have been transmitted, the VTU-O shall transmit O-P-TEQ for $T_{VTU-R\_TEQ}$ symbols. The VTU-R shall transmit $T_{VTU-O\_EC} + T_{VTU-R\_TEQ}$ symbols of R-P-QUIET 3 immediately after all $T_{VTU-O\_TEQ}$ symbols of R-P-TEQ have been transmitted. During the transmission of O-P-TEQ, the VTU-R may train its TEQ. + +Immediately after the VTU-O has transmitted all $T_{VTU-R\_TEQ}$ symbols of O-P-TEQ, it shall transmit O-P-PILOT 3 for $T_{VTU-R\_EC}$ symbols. After the VTU-R has transmitted all $T_{VTU-O\_EC} + T_{VTU-R\_TEQ}$ symbols of R-P-QUIET 3, it shall transmit R-P-ECT for $T_{VTU-R\_EC}$ symbols. During this stage, the VTU-R may train its echo canceller. + +After transmitting the last symbol of O-P-PILOT 3, the VTU-O shall transmit $T_{\text{Periodic}}$ symbols of O-P-PERIODIC 2. After transmitting the last symbol of R-P-ECT, the VTU-R shall likewise transmit $T_{\text{Periodic}}$ symbols of R-P-PERIODIC 2. During this stage, there is bidirectional transmission of periodic signals that may be used to make further adjustments to the TEQ at each receiver. After transmitting the last symbol of O-P-PERIODIC 2, the VTU-O shall transmit O-P-TRAINING 2. After transmitting the last symbol of R-P-PERIODIC 2, the VTU-R shall transmit R-P-TRAINING 2. At this point, the SOC shall be re-activated and the VTU-O shall send O-IDLE and the VTU-R shall send R-IDLE. + +The VTU-R shall send R-IDLE for at least the first 128 symbols of R-P-TRAINING 2. The first message after that shall be R-TA\_UPDATE. R-TA\_UPDATE is used to communicate the current setting of the timing advance and to indicate the preferred and maximum values of the timing advance that the VTU-R can accommodate. The VTU-O shall acknowledge the reception of R-TA\_UPDATE by sending O-TA\_UPDATE containing the final value of the timing advance. The VTU-R shall acknowledge the reception of the O-TA\_UPDATE message by sending R-ACK. The adjusted timing advance value shall be activated 5 symbols after the completion of R-ACK. The messages R-TA\_UPDATE and O-TA\_UPDATE also establish the number of SOC bytes per DMT symbol that will be used during the channel analysis and exchange phase. + +To provide high robustness, both VTUs shall use the RQ protocol, as described in clause 12.2.2.2. Thus, the receiving VTU may ask for a retransmission of any message that was not correctly received. + +After receiving R-ACK, the VTU-O shall continue to transmit O-P-TRAINING 2 for a duration of at least 64 symbols, and then shall indicate the end of the training phase by transmitting O-P-SYNCHRO 5. The VTU-R shall acknowledge the detection of O-P-SYNCHRO 5 by transmitting R-P-SYNCHRO 5 within a time period of 64 DMT symbols. After that, the VTU-R shall transition into the channel analysis and exchange phase. The VTU-O shall transition to the channel analysis and exchange phase after transmission of O-P-SYNCHRO 5. + +NOTE 3 – Figure 12-8 shows the complete training phase with TEQ and EC training stages, both upstream and downstream. The training phase may be shortened if some or all of these stages are not required. Since the lengths are determined based on the values communicated by the VTU-O and VTU-R during the channel discovery phase, one or more of the training stages can be reduced to the minimum length, thereby shortening the overall training time. + +From the start of the training phase and for the remainder of initialization, the VTU-O and VTU-R shall transmit signals with the PSDs that are determined at the end of the channel discovery phase (i.e., including power cut-backs in the upstream and downstream transmission directions), as described in clause 12.3.4.3. + +The signals and SOC messages sent by the VTU-O during the training phase are summarized in Table 12-39, and the signals and SOC messages sent by the VTU-R during the training phase are summarized in Table 12-40. The protocol used for SOC messages is provided, where applicable, in parentheses in the column labelled "SOC state". + +**Table 12-39 – VTU-O signals and SOC messages in the training phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages and IDLE flags | SOC state | +|----------------|----------------------|----------------------------------------|-----------------------------|-----------| +| O-P-TRAINING 1 | Non-periodic | Variable | None | Inactive | +| O-P-SYNCHRO 4 | Non-periodic | 15 | None | Inactive | +| O-P-PILOT 2 | Non-periodic | $T_{\text{VTU-O\_TEQ}}$ | None | Inactive | +| O-P-TEQ | Periodic | $T_{\text{VTU-R\_TEQ}}$ | None | Inactive | +| O-P-ECT | Vendor discretionary | $T_{\text{VTU-O\_EC}}$ | None | Inactive | +| O-P-PILOT 3 | Non-periodic | $T_{\text{VTU-R\_EC}}$ | None | Inactive | + +**Table 12-39 – VTU-O signals and SOC messages in the training phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages and IDLE flags | SOC state | +|----------------|--------------|----------------------------------------|-----------------------------|-------------| +| O-P-PERIODIC 2 | Periodic | $T_{\text{Periodic}}$ | None | Inactive | +| O-P-TRAINING 2 | Non-periodic | Variable | O-IDLE,
O-TA_UPDATE | Active (RQ) | +| O-P-SYNCHRO 5 | Non-periodic | 15 | None | Inactive | + +**Table 12-40 – VTU-R signals and SOC messages in the training phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages and IDLE flags | SOC state | +|----------------|----------------------|------------------------------------------------|-----------------------------|-------------| +| R-P-QUIET 2 | None | Variable, $\leq 4\,096$ | None | Inactive | +| R-P-TRAINING 1 | Non-periodic | Variable, $> T_{\text{MIN-R-P-Train}}$ | None | Inactive | +| R-P-SYNCHRO 4 | Non-periodic | 15 | None | Inactive | +| R-P-TEQ | Periodic | $T_{\text{VTU-O\_TEQ}}$ | None | Inactive | +| R-P-QUIET 3 | None | $T_{\text{VTU-R\_TEQ}} + T_{\text{VTU-O\_EC}}$ | None | Inactive | +| R-P-ECT | Vendor discretionary | $T_{\text{VTU-R\_EC}}$ | None | Inactive | +| R-P-PERIODIC 2 | Periodic | $T_{\text{Periodic}}$ | None | Inactive | +| R-P-TRAINING 2 | Non-periodic | Variable | R-IDLE,
R-TA_UPDATE | Active (RQ) | +| R-P-SYNCHRO 5 | Non-periodic | 15 | None | Inactive | + +#### 12.3.4.2 SOC message exchange during the training phase + +Figure 12-9 illustrates the SOC message exchange between the VTU-O and VTU-R during the training phase. It also summarizes the content of each message. + +![Diagram showing the SOC message exchange during the training phase. It consists of three stacked boxes representing messages: R-TA_UPDATE (top), O-TA_UPDATE (middle), and R-ACK (bottom).](bf2e682e30eceee92acd2243018fa614_img.jpg) + +The diagram illustrates the sequence of SOC messages exchanged during the training phase. It consists of three stacked rectangular boxes, each representing a message. The top box is labeled **R-TA\_UPDATE** and contains four bullet points: Current value of timing advance, Timing advance correction, Maximum value of timing advance, and Desired number of SOC bytes in O-P-MEDLEY and R-P-MEDLEY. The middle box is labeled **O-TA\_UPDATE** and contains two bullet points: Adjustment of timing advance and Desired number of SOC bytes in O-P-MEDLEY and R-P-MEDLEY. The bottom box is labeled **R-ACK** and contains one bullet point: Acknowledges the reception of the O-TA-UPDATE message. + +Diagram showing the SOC message exchange during the training phase. It consists of three stacked boxes representing messages: R-TA\_UPDATE (top), O-TA\_UPDATE (middle), and R-ACK (bottom). + +**Figure 12-9 – SOC message exchange during the training phase** + +##### 12.3.4.2.1 VTU-O messages sent during the training phase + +###### 12.3.4.2.1.1 O-TA\_UPDATE + +The full list of parameters carried by the O-TA\_UPDATE message is shown in Table 12-41. + +**Table 12-41 – Description of message O-TA\_UPDATE** + +| | Field name | Format | +|---|---------------------------------------------------------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | Timing advance correction | 2 bytes | +| 3 | B ex-ds-O (Desired number of SOC bytes per DMT symbol in O-P-MEDLEY) | 1 byte | +| 4 | B ex-us-O (Desired number of SOC bytes per DMT symbol in R-P-MEDLEY) | 1 byte | +| 5 | ITU-T G.998.4 parameter field | Variable length | +| 6 | ITU-T G.993.5 parameter field | Variable length | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Timing advance correction" defines the timing advance correction that shall be used with respect to the current timing advance. It shall be expressed in samples at the upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. Positive values shall indicate that the transmitted symbol will be advanced more with respect to the received symbol. + +Field #3 "Bex-ds-O" specifies the VTU-O's choice for the number of SOC bytes per DMT symbol that should be used to modulate O-P-MEDLEY. This number shall be either one or two. The actual number of SOC bytes per DMT symbol shall be the minimum of the values indicated in O-TA\_UPDATE and R-TA\_UPDATE (i.e., equal to $\min(B_{ex-ds-O}, B_{ex-ds-R})$ ). + +Field #4 "Bex-us-O" specifies the VTU-O's choice for the number of SOC bytes per DMT symbol that should be used to modulate R-P-MEDLEY. This number shall be either one or two. The actual number of SOC bytes per DMT symbol shall be the minimum of the values indicated in O-TA\_UPDATE and R-TA\_UPDATE (i.e., equal to $\min(B_{ex-us-O}, B_{ex-us-R})$ ). + +Field #5 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #6 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 5 and 6 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +#### 12.3.4.2.2 VTU-R messages sent during the training phase + +##### 12.3.4.2.2.1 R-TA\_UPDATE + +The full list of parameters carried by the R-TA\_UPDATE message is shown in Table 12-42. + +**Table 12-42 – Description of message R-TA\_UPDATE** + +| | Field name | Format | +|---|---------------------------------------------------------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | Current timing advance | 2 bytes | +| 3 | Timing advance correction | 2 bytes | +| 4 | Maximum value of timing advance | 2 bytes | +| 5 | B ex-ds-R (Desired number of SOC bytes per DMT symbol in O-P-MEDLEY) | 1 byte | +| 6 | B ex-us-R (Desired number of SOC bytes per DMT symbol in R-P-MEDLEY) | 1 byte | +| 7 | ITU-T G.998.4 parameter field | Variable length | +| 8 | ITU-T G.993.5 parameter field | Variable length | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Current timing advance" gives the timing advance currently being used by the VTU-R. The field is expressed in samples at the upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. + +Field #3 "Timing advance correction" indicates the timing advance correction, with respect to the current timing advance, preferred by the VTU-R in samples at the upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. Positive values shall indicate that the transmitted symbol will be advanced more with respect to the received symbol. + +Field #4 "Maximum value of timing advance" indicates the maximum value of timing advance that the VTU-R can accommodate in samples at the current upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. + +Field #5 "Bex-ds-R" specifies the VTU-R's choice for the number of SOC bytes per DMT symbol that should be used to modulate O-P-MEDLEY. This number shall be either one or two. The actual number of SOC bytes per DMT symbol shall be the minimum of the values indicated in O-TA\_UPDATE and R-TA\_UPDATE (i.e., equal to $\min(B_{ex-ds-O}, B_{ex-ds-R})$ ). + +Field #6 "Bex-us-R" specifies the VTU-R's choice for the number of SOC bytes per DMT symbol that should be used to modulate R-P-MEDLEY. This number shall be either one or two. The actual number of SOC bytes per DMT symbol shall be the minimum of the values indicated in O-TA\_UPDATE and R-TA\_UPDATE (i.e., equal to $\min(B_{ex-us-O}, B_{ex-us-R})$ ). + +Field #7 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #8 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 7 and 8 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +#### 12.3.4.2.2.2 R-ACK + +R-ACK is a one-byte message that acknowledges correct reception of the O-TA\_UPDATE message. The format of the message shall be as specified in clause 12.2.1, and the payload shall be as specified in Table 12-6. + +#### 12.3.4.3 Signals transmitted during the training phase + +All signals transmitted during the training phase, except O-P-TEQ and R-P-TEQ, shall use only subcarriers from the MEDLEYds set in the downstream direction and subcarriers from the MEDLEYus set in the upstream direction. O-P-TEQ and R-P-TEQ also use out-of-MEDLEY subcarriers, as described in clauses 12.3.4.3.1.4 and 12.3.4.3.2.4. + +The transmit PSD of downstream signals with non-zero output power shall comply with the downstream MEDLEY reference PSD mask (MREFMASKds) that was established at the end of the channel discovery phase in both the passband and the stopbands. The values of $2N_{ds}$ and CE shall be those determined at the end of the channel discovery phase and communicated in Fields #7 and #4 in O-PRM, respectively. The values of $\beta_{ds}$ and cyclic prefix length shall be as communicated in Field #6 and Field #5 of O-PRM, respectively. + +The transmit PSD of all upstream signals with non-zero output power shall comply with the upstream MEDLEY reference PSD mask (MREFMASKus) that was established at the end of the channel discovery phase in both the passband and the stopbands. The values of $2N_{us}$ and CE shall be those determined at the end of the channel discovery phase and communicated in Field #6 of R-PRM and Field #4 in O-PRM, respectively. The values of $\beta_{us}$ and cyclic prefix length shall be those communicated in Fields #5 and #4 of R-PRM, respectively. + +##### 12.3.4.3.1 Signals transmitted by the VTU-O + +###### 12.3.4.3.1.1 O-P-TRAINING 1 + +The O-P-TRAINING 1 signal allows the VTU-R to re-synchronize and establish correct symbol timing. During transmission of O-P-TRAINING 1, the SOC is in its inactive state. + +The duration of O-P-TRAINING 1 is variable. The VTU-O terminates O-P-TRAINING 1 by transmitting O-P-SYNCHRO 4. + +O-P-TRAINING 1 shall be composed of all subcarriers in the MEDLEYds set. These subcarriers shall be modulated by 4-QAM. O-P-TRAINING 1 carries one byte per DMT symbol. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +The one byte carried by O-P-TRAINING 1 shall be the output of a PRBS generator with the same polynomial as the PRBS used for the quadrant scrambler (see clause 12.3.6.2). This PRBS generator shall not be reset and shall not skip any bits between DMT symbols. The initial state of this PRBS (for the first symbol of O-P-TRAINING 1) shall be all ones. The mapping of bits to subcarriers shall be as shown in Table 12-43. + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of the MEDLEYds subcarriers shall be equal to the downstream MEDLEY reference PSD (MREFPSDds) communicated in Field #2 of O-PRM. + +**Table 12-43 – Bit mapping for O-P-TRAINING 1** + +| Subcarrier index | Constellation point | +|-------------------------------|----------------------------------| +| Even | 00 | +| 1, 11, 21, ..., $10n+1$ , ... | First 2 bits from the PRBS byte | +| 3, 13, 23, ..., $10n+3$ , ... | Second 2 bits from the PRBS byte | +| 5, 15, 25, ..., $10n+5$ , ... | Third 2 bits from the PRBS byte | +| 7, 17, 27, ..., $10n+7$ , ... | Fourth 2 bits from the PRBS byte | +| 9, 19, 29, ..., $10n+9$ , ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1,b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +#### 12.3.4.3.1.2 O-P-SYNCHRO 4 + +O-P-SYNCHRO 4 provides an exact time marker for transitions from O-P-TRAINING 1 to O-P-PILOT 2. During transmission of O-P-SYNCHRO 4, the SOC is in its inactive state. + +The duration of O-P-SYNCHRO 4 is 15 DMT symbols. + +O-P-SYNCHRO 4 shall use all subcarriers in the MEDLEYds set modulated by 4-QAM. The value 11 shall be mapped to all MEDLEYds subcarriers for the first 5 and the last 5 DMT symbols. The value 00 shall be mapped to all of the MEDLEYds subcarriers for the middle 5 DMT symbols. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of the MEDLEYds subcarriers in O-P-SYNCHRO 4 shall be the same as for O-P-TRAINING 1. + +#### 12.3.4.3.1.3 O-P-PILOT 2 + +The O-P-PILOT 2 signal is intended to allow the VTU-R to maintain loop timing during VTU-O TEQ training. During O-P-PILOT 2 the SOC is in its inactive state. + +The duration of O-P-PILOT 2 is $T_{VTU-O\_TEQ}$ DMT symbols with CE. The value of $T_{VTU-O\_TEQ}$ shall be set to the maximum of the durations requested by the VTU-R in R-PRM and by the VTU-O in O-PRM. + +O-P-PILOT 2 consists only of the pilot tones that were chosen by the VTU-R and communicated to the VTU-O in the Field #5 of R-MSG 1 during the channel discovery phase. A value of 00 shall be mapped to all pilot tones with 4-QAM modulation during every symbol of O-P-PILOT 2. + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The O-P-PILOT 2 signal shall respect MREFMASKds as established at the conclusion of the channel discovery phase. The transmit power of pilot tones shall be set to 0 if the second MSB of the O-P-PILOT settings field of R-MSG 1 during the channel discovery phase is set to ZERO. + +#### 12.3.4.3.1.4 O-P-TEQ + +O-P-TEQ is a periodic signal. It allows the VTU-R to train its TEQ. During the transmission of O-P-TEQ, the SOC is in its inactive state. + +The duration of O-P-TEQ is $T_{\text{VTU-R\_TEQ}}$ DMT symbols with CE. The value of $T_{\text{VTU-R\_TEQ}}$ shall be set to the maximum of the durations requested by the VTU-R in R-PRM and by the VTU-O in O-PRM. + +O-P-TEQ shall use all subcarriers from the MEDLEYds set, as well as the out-of-MEDLEYds subcarriers with indices between 1 and $t_{\text{DS1\_stop}} + 32$ , where $t_{\text{DS1\_stop}}$ is the highest-index subcarrier in the MEDLEYds set included in DS1. + +O-P-TEQ shall map the 4-QAM value of 11 on each subcarrier. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +O-P-TEQ shall be constructed as described in clause 12.3.6.1. + +The transmit PSD of the MEDLEYds subcarriers in O-P-TEQ shall be the same as for O-P-TRAINING 1. The transmit PSD shall incorporate the $tss_i$ values that were sent by the VTU-O during the channel discovery phase (see clause 12.3.3.2.1.3). + +#### 12.3.4.3.1.5 O-P-ECT + +The O-P-ECT signal allows the VTU-O to train its echo canceller. During transmission of O-P-ECT, the SOC is in its inactive state. + +The duration of O-P-ECT is $T_{\text{VTU-O\_EC}}$ DMT symbols with CE. The value of $T_{\text{VTU-O\_EC}}$ shall be as indicated by the VTU-O in O-PRM. + +O-P-ECT is a vendor-discretionary signal. However, in order to allow the VTU-R to maintain loop timing, O-P-ECT shall include any pilot tones selected by the VTU-R during the channel discovery phase. + +The PSD of O-P-ECT shall respect MREFMASKds as established at the conclusion of the channel discovery phase. + +#### 12.3.4.3.1.6 O-P-PILOT 3 + +The O-P-PILOT 3 signal is intended to allow the VTU-R to maintain loop timing during echo canceller training. During the transmission of O-P-PILOT 3, the SOC is in its inactive state. + +The duration of O-P-PILOT 3 is $T_{\text{VTU-R\_EC}}$ DMT symbols with CE. The value of $T_{\text{VTU-R\_EC}}$ shall be as indicated by the VTU-R in R-PRM. + +O-P-PILOT 3 consists only of the pilot tones that were chosen by the VTU-R and communicated to the VTU-O in Field #5 of R-MSG 1 during the channel discovery phase. A value of 00 shall be mapped to all pilot tones with 4-QAM modulation during every symbol of O-P-PILOT 3. + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The O-P-PILOT 3 signal shall respect MREFMASKds as established at the conclusion of the channel discovery phase. The transmit power of pilot tones shall be set to 0 if the third MSB of the O-P-PILOT settings field of R-MSG 1 during the channel discovery phase is set to ZERO. + +#### 12.3.4.3.1.7 O-P-PERIODIC 2 + +O-P-PERIODIC 2 is a periodic signal. During the transmission of O-P-PERIODIC 2, the SOC is in its inactive state. + +The duration of O-P-PERIODIC 2, $T_{\text{Periodic}}$ DMT symbols with CE, is the maximum of the durations requested by the VTU-R in R-PRM and by the VTU-O in O-PRM. + +O-P-PERIODIC 2 shall be composed of all subcarriers in the MEDLEYds set. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to all of the subcarriers. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +O-P-PERIODIC 2 shall be constructed as described in clause 12.3.6.1. + +The transmit PSD of the MEDLEYds subcarriers in O-P-PERIODIC 2 shall be the same as for O-P-TRAINING 1. + +#### 12.3.4.3.1.8 O-P-TRAINING 2 + +The O-P-TRAINING 2 signal allows the VTU-R to re-establish SOC message exchange between the VTU-O and VTU-R. During the transmission of O-P-TRAINING 2, the SOC is in its active state. + +The duration of O-P-TRAINING 2 is variable. The VTU-O terminates O-P-TRAINING 2 by transmitting O-P-SYNCHRO 5, which completes the training phase. + +O-P-TRAINING 2 shall be composed of all subcarriers in the MEDLEYds set modulated by 4-QAM. + +O-P-TRAINING 2 shall carry one byte of information per DMT symbol. The mapping of bits to subcarriers shall be as summarized in Table 12-44. + +**Table 12-44 – Bit mapping for O-P-TRAINING 2** + +| Subcarrier index | Constellation point | +|-------------------------------|--------------------------| +| Even | 00 | +| 1, 11, 21, ..., $10n+1$ , ... | SOC message bits 0 and 1 | +| 3, 13, 23, ..., $10n+3$ , ... | SOC message bits 2 and 3 | +| 5, 15, 25, ..., $10n+5$ , ... | SOC message bits 4 and 5 | +| 7, 17, 27, ..., $10n+7$ , ... | SOC message bits 6 and 7 | +| 9, 19, 29, ..., $10n+9$ , ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1,b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of the MEDLEYds subcarriers in O-P-TRAINING 2 shall be the same as for O-P-TRAINING 1. + +#### 12.3.4.3.1.9 O-P-SYNCHRO 5 + +The O-P-SYNCHRO 5 is a signal that provides an exact time marker for transitions from O-P-TRAINING 2 to O-P-MEDLEY (the beginning of the channel analysis and exchange phase). + +O-P-SYNCHRO 5 shall be identical to O-P-SYNCHRO 4. + +#### 12.3.4.3.2 Signals transmitted by the VTU-R + +##### 12.3.4.3.2.1 R-P-QUIET 2 + +R-P-QUIET 2 shall provide a zero output voltage at the U reference point. All subcarriers shall be + +transmitted at zero power. The duration of R-P-QUIET 2 is left to the discretion of the VTU-R but shall not exceed 4 096 DMT symbols with CE. + +#### 12.3.4.3.2.2 R-P-TRAINING 1 + +The R-P-TRAINING 1 signal is the first signal sent by the VTU-R after re-establishing synchronization. During transmission of R-P-TRAINING 1, the SOC is in its inactive state. + +The duration of R-P-TRAINING 1 is variable. + +R-P-TRAINING 1 shall be composed of all subcarriers in the MEDLEYus set. These subcarriers shall be modulated by 4-QAM. R-P-TRAINING 1 carries one byte per DMT symbol. The one byte and the mapping of bits to subcarriers shall be as shown in Table 12-45. + +**Table 12-45 – Bit mapping for R-P-TRAINING 1** + +| Subcarrier index | Constellation point | +|----------------------------|---------------------| +| Even | 00 | +| 1, 11, 21, ..., 10n+1, ... | 01 | +| 3, 13, 23, ..., 10n+3, ... | 11 | +| 5, 15, 25, ..., 10n+5, ... | 11 | +| 7, 17, 27, ..., 10n+7, ... | 10 | +| 9, 19, 29, ..., 10n+9, ... | 00 | + +The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{us}$ . + +The transmit PSD of the MEDLEYus subcarriers in R-P-TRAINING 1 shall be equal to the upstream MEDLEY reference PSD (MREFPSDus) communicated in Field #2 of R-PRM. + +#### 12.3.4.3.2.3 R-P-SYNCHRO 4 + +R-P-SYNCHRO 4 provides an exact time marker for transition from R-P-TRAINING 1 to R-P-TEQ. During transmission of R-P-SYNCHRO 4, the SOC is in its inactive state. + +The duration of R-P-SYNCHRO 4 is 15 DMT symbols. + +R-P-SYNCHRO 4 shall use all subcarriers in the MEDLEYus set modulated by 4-QAM. The value 11 shall be mapped to all MEDLEYus subcarriers for the first 5 and the last 5 DMT symbols. The value 00 shall be mapped to all MEDLEYus subcarriers for the middle 5 DMT symbols. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{us}$ . + +The transmit PSD of the MEDLEYus subcarriers in R-P-SYNCHRO 4 shall be the same as for R-P-TRAINING 1. + +#### 12.3.4.3.2.4 R-P-TEQ + +R-P-TEQ is a periodic signal. It allows the VTU-O to train its TEQ. During the transmission of R-P-TEQ, the SOC is in its inactive state. + +The duration of R-P-TEQ is $T_{VTU-O\_TEQ}$ DMT symbols with CE. The value of $T_{VTU-O\_TEQ}$ shall be set + +to the maximum of the durations requested by the VTU-R in R-PRM and by the VTU-O in O-PRM. + +R-P-TEQ shall use all of the subcarriers from the MEDLEYus set, as well as the out-of-MEDLEYus subcarriers with indices between 1 and $tUSO\_stop + 32$ , where $tUSO\_stop$ is the highest-index subcarrier included in US0. + +R-P-TEQ shall map the 4-QAM value of 11 on each subcarrier. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +R-P-TEQ shall be constructed as described in clause 12.3.6.1. + +The transmit PSD of the MEDLEYus subcarriers in R-P-TEQ shall be the same as for R-P-TRAINING 1. The transmit PSD shall incorporate the $tss_i$ values that were sent by the VTU-R during the channel discovery phase (see clause 12.3.3.2.2.3). + +#### **12.3.4.3.2.5 R-P-QUIET 3** + +R-P-QUIET 3 shall provide a zero output voltage at the U reference point. All subcarriers shall be transmitted at zero power. The duration of R-P-QUIET 3 shall be $T_{VTU-R\_TEQ} + T_{VTU-O\_EC}$ DMT symbols with CE. + +#### **12.3.4.3.2.6 R-P-ECT** + +The R-P-ECT signal allows the VTU-R to train its echo canceller. R-P-ECT is a vendor-discretionary signal. During transmission of R-P-ECT, the SOC is in its inactive state. + +The duration of R-P-ECT is $T_{VTU-R\_EC}$ DMT symbols with CE. The value $T_{VTU-R\_EC}$ shall be as indicated by the VTU-R in R-PRM. + +The PSD of R-P-ECT shall respect MREFMASKus as established at the conclusion of the channel discovery phase. + +#### **12.3.4.3.2.7 R-P-PERIODIC 2** + +R-P-PERIODIC 2 is a periodic signal. During the transmission of R-P-PERIODIC 2, the SOC is in its inactive state. + +The duration of R-P-PERIODIC 2, $T_{Periodic}$ DMT symbols with CE, is the maximum of the durations requested by the VTU-O in O-PRM and by the VTU-R in R-PRM. + +R-P-PERIODIC 2 shall be composed of all subcarriers in the MEDLEYus set. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to each subcarrier. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +R-P-PERIODIC 2 shall be constructed as described in clause 12.3.6.1. + +The transmit PSD of the MEDLEYus subcarriers in R-P-PERIODIC 2 shall be the same as for R-P-TRAINING 1. + +#### **12.3.4.3.2.8 R-P-TRAINING 2** + +The R-P-TRAINING 2 signal re-establishes SOC message exchange between the VTU-O and VTU-R. During transmission of R-P-TRAINING 2, the SOC is in its active state. + +The duration of R-P-TRAINING 2 is variable. The VTU-R terminates R-P-TRAINING 2 when it receives O-P-SYNCHRO 5. + +R-P-TRAINING 2 shall be composed of all subcarriers in the MEDLEYus set. These subcarriers shall be modulated by 4-QAM. R-P-TRAINING 2 shall carry one byte of information per DMT symbol. The bit mapping shall be as summarized in Table 12-46. + +**Table 12-46 – Bit mapping for R-P-TRAINING 2** + +| Subcarrier index | Constellation point | +|----------------------------|--------------------------| +| Even | 00 | +| 1, 11, 21, ..., 10n+1, ... | SOC message bits 0 and 1 | +| 3, 13, 23, ..., 10n+3, ... | SOC message bits 2 and 3 | +| 5, 15, 25, ..., 10n+5, ... | SOC message bits 4 and 5 | +| 7, 17, 27, ..., 10n+7, ... | SOC message bits 6 and 7 | +| 9, 19, 29, ..., 10n+9, ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers 10n+1 means that the two-bit value (b1,b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{us}$ . + +The transmit PSD of the MEDLEYus subcarriers in R-P-TRAINING 2 shall be the same as for R-P-TRAINING 1. + +#### 12.3.4.3.2.9 R-P-SYNCHRO 5 + +R-P-SYNCHRO 5 is a signal that provides an exact time marker for transition from R-P-TRAINING 2 to R-P-MEDLEY (the beginning of the channel analysis and exchange phase). + +R-P-SYNCHRO 5 shall be identical to R-P-SYNCHRO 4. + +### 12.3.5 Channel analysis and exchange phase + +#### 12.3.5.1 Overview + +During the channel analysis and exchange phase, SNR estimation is performed. Both VTUs exchange their capabilities and the final configuration for both upstream and downstream transmission is selected on the basis of these capabilities. + +Figure 12-10 presents the timing diagram for the stages of the channel analysis and exchange phase. It gives an overview of the sequence of signals transmitted and the sequence of SOC messages sent by the VTU-O and VTU-R during the channel analysis and exchange phase. The two inner columns show the sequences of signals that are transmitted (see clause 12.3.5.3). The two outer columns show the messages that are sent over the SOC (see clause 12.3.5.2). The shaded areas correspond to periods of time when the SOC is in its inactive state. + +![Timing diagram for the stages of the channel analysis and exchange phase. The diagram is divided into Downstream and Upstream sections. Downstream includes SOC Messages (O-IDLE, O-MSG 1, O-TPS, O-PMS, O-PMD) and Signals (O-P-MEDLEY, O-P-SYNCHRO 6). Upstream includes Signals (R-P-MEDLEY, R-P-SYNCHRO 6) and SOC Messages (R-IDLE, R-MSG 2, R-TPS-ACK, R-PMS, R-PMD). Vertical arrows on the sides indicate the CHANNEL ANALYSIS and EXCHANGE phase (VTU-O and VTU-R).](09da3f926780c5e1a7db91a5abfaa3d0_img.jpg) + +The diagram illustrates the timing sequence for the channel analysis and exchange phase between a VTU-O (Downstream) and a VTU-R (Upstream). + +**Downstream (VTU-O) Stages:** + +- SOC Messages:** O-IDLE, O-MSG 1, O-TPS, O-PMS, O-PMD. +- Signals:** O-P-MEDLEY, O-P-SYNCHRO 6. + +**Upstream (VTU-R) Stages:** + +- Signals:** R-P-MEDLEY, R-P-SYNCHRO 6. +- SOC Messages:** R-IDLE, R-MSG 2, R-TPS-ACK, R-PMS, R-PMD. + +The vertical arrows on the left and right sides of the diagram are labeled "CHANNEL ANALYSIS and EXCHANGE phase (VTU-O)" and "CHANNEL ANALYSIS and EXCHANGE phase (VTU-R)" respectively, indicating the duration of the phase. + +G.993.2(15)\_F12-10 + +Timing diagram for the stages of the channel analysis and exchange phase. The diagram is divided into Downstream and Upstream sections. Downstream includes SOC Messages (O-IDLE, O-MSG 1, O-TPS, O-PMS, O-PMD) and Signals (O-P-MEDLEY, O-P-SYNCHRO 6). Upstream includes Signals (R-P-MEDLEY, R-P-SYNCHRO 6) and SOC Messages (R-IDLE, R-MSG 2, R-TPS-ACK, R-PMS, R-PMD). Vertical arrows on the sides indicate the CHANNEL ANALYSIS and EXCHANGE phase (VTU-O and VTU-R). + +**Figure 12-10 – Timing diagram for the stages of the channel analysis and exchange phase** + +NOTE – In the exchange of the SOC messages identified in Figure 12-10, the rules of the communication protocol of clause 12.2.2 apply. Some messages sent in the SOC may require segmentation; although this is not shown in Figure 12-10, the segmented message elements and their corresponding acknowledgements are sent via the SOC as per the communication protocol of clause 12.2.2. + +The channel analysis and exchange phase involves the following steps as shown in Figure 12-10: + +- 1) The VTU-O sends the O-MSG 1 message, which contains its capabilities and a number of (downstream) configuration parameters. +- 2) The VTU-R replies by sending the R-MSG 2 message, which indicates its capabilities. +- 3) The VTU-O sends the O-TPS message to indicate the configuration of the bearer channels and their required capabilities for both the upstream and the downstream directions. +- 4) The VTU-R acknowledges the O-TPS message with the R-TPS-ACK message. +- 5) The VTU-O conveys the upstream PMS-TC (framing) parameters by sending the O-PMS message. +- 6) The VTU-R conveys the downstream PMS-TC (framing) parameters by sending the R-PMS message. +- 7) The VTU-O sends the O-PMD message, which contains the bits, gains and tone ordering tables for the upstream PMD. +- 8) The VTU-R sends the R-PMD message, which contains the bits, gains and tone ordering tables for the downstream PMD. + +After sending R-PMD, the VTUs are ready to transition to showtime. The trigger for stepping into showtime shall be given by O-P-SYNCHRO 6 and R-P-SYNCHRO 6 for the downstream and upstream transmission directions, respectively. R-P-SYNCHRO 6 shall be transmitted within 64 symbols of detecting O-P-SYNCHRO 6. + +The first DMT symbol following O-P-SYNCHRO 6 shall be the first downstream symbol of showtime. Likewise, the first DMT symbol following R-P-SYNCHRO 6 shall be the first upstream symbol of showtime. The PMD, PMS-TC and TPS-TC parameter settings negotiated during the channel analysis and exchange phase shall be set starting from the first symbol of showtime. + +The signals and SOC messages sent by the VTU-O during the channel analysis and exchange phase are summarized in Table 12-47, and the signals and SOC messages sent by the VTU-R during the channel analysis and exchange phase are summarized in Table 12-48. The protocol used for SOC messages is provided, where applicable, in parentheses in the column labelled "SOC state". + +**Table 12-47 – VTU-O signals and SOC messages in the channel analysis and exchange phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages | SOC state | +|---------------|--------------|----------------------------------------|------------------------------|-------------| +| O-P-MEDLEY | Non-periodic | Variable | O-MSG 1, O-TPS, O-PMS, O-PMD | Active (RQ) | +| O-P-SYNCHRO 6 | Non-periodic | 15 | None | Inactive | + +**Table 12-48 – VTU-R signals and SOC messages in the channel analysis and exchange phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages | SOC state | +|---------------|--------------|----------------------------------------|----------------------------------------|-------------| +| R-P-MEDLEY | Non-periodic | Variable | R-MSG 2,
R-TPS-ACK, R-PMS,
R-PMD | Active (RQ) | +| R-P-SYNCHRO 6 | Non-periodic | 15 | None | Inactive | + +### 12.3.5.2 SOC messages exchanged during channel analysis and exchange phase + +Figure 12-11 illustrates the SOC message exchange between the VTU-O and VTU-R during the channel analysis and exchange phase. It also summarizes the content of each message. + +![Diagram of SOC message exchange between VTU-O and VTU-R](e8548116529ee9e05c70ce229d67d749_img.jpg) + +| | | | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--| +|

O-MSG 1

  • Convey VTU-O capabilities (e.g., TPS-TC, PMS-TC, ToD-TC)
  • Convey DS configuration parameters
| | | +| |

R-MSG 2

  • Convey VTU-R capabilities (e.g., TPS-TC, PMS-TC, ToD-TC)
| | +|

O-TPS

  • Select combinations of TPS-TC and bearer channels
  • Set properties of TPS-TCs
  • Set properties of ToD-TC
| | | +| |

R-TPS-ACK

  • Acknowledge reception of the O-TPS message
| | +|

O-PMS

  • PMS-TC and framing parameter selection for upstream
| | | +| |

R-PMS

  • PMS-TC and framing parameter selection for downstream
  • Indication of whether erasure decoding is used
| | +|

O-PMD

  • Transmission of (b_i, g_i, t_i) for use in upstream
  • Selection of trellis coding for upstream
| | | +| |

R-PMD

  • Transmission of (b_i, g_i, t_i) for use in downstream
  • Selection of trellis coding for downstream
| | + +Diagram of SOC message exchange between VTU-O and VTU-R + +**Figure 12-11 – SOC messages exchanged during the channel analysis and exchange phase** + +#### 12.3.5.2.1 VTU-O messages sent during the channel analysis and exchange phase + +##### 12.3.5.2.1.1 O-MSG 1 + +The O-MSG 1 message contains the capabilities of the VTU-O and the requirements for downstream transmission (such as margin). The full list of parameters carried by the O-MSG 1 message is shown in Table 12-49. + +**Table 12-49 – Description of message O-MSG 1** + +| | Field name | Format | +|----|-------------------------------------------------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | Downstream target SNR margin (TARSNRMds) | 2 bytes | +| 3 | Downstream minimum SNR margin (MINSNRMsds) | 2 bytes | +| 4 | Downstream maximum SNR margin (MAXSNRMds) | 2 bytes | +| 5 | RA-MODE | 1 byte | +| 6 | NTR | 1 byte | +| 7 | TPS-TC capabilities | see Table 12-50 | +| 8 | PMS-TC capabilities | see Table 12-52 | +| 9 | Downstream Rate adaptation downshift SNR margin (RA-DSNRMsds) | 2 bytes | +| 10 | Downstream Rate adaptation downshift time interval (RA-DTIMEds) | 2 bytes | +| 11 | Downstream Rate adaptation upshift SNR margin (RA-USNRMsds) | 2 bytes | +| 12 | Downstream Rate adaptation upshift time interval (RA-UTIMEds) | 2 bytes | +| 13 | Support of "Flexible OH frame Type 2" downstream and INM_INPEQ_FORMATds | 1 byte | +| 14 | SOS Multi-step activation downstream | 1 byte | +| 15 | SOS Multi-step activation upstream | 1 byte | +| 16 | MIN-SOS-BR-ds0 | 2 bytes | +| 17 | MIN-SOS-BR-ds1 | 2 bytes | +| 18 | SOS-TIME-ds | 1 byte | +| 19 | SOS-NTONES-ds | 1 byte | +| 20 | SOS-CRC-ds | 2 bytes | +| 21 | MAX-SOS-ds | 1 byte | +| 22 | SNRMOFFSET-ROC-ds | 2 bytes | +| 23 | INPMIN-ROC-ds | 1 byte | +| 24 | ITU-T G.998.4 parameter field | Variable length | +| 25 | ITU-T G.993.5 parameter field | Variable length | +| 26 | REINIT_TIME_THRESHOLDSds | 1 byte | +| 27 | Time synchronization capability | 1 byte | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Downstream target SNR margin (TARSNRMds)" indicates the target SNR margin of the VTU-R receiver. The definition and use of this parameter shall be the same as for the parameter "Downstream Target Noise Margin (TARSNRMds)" specified in [ITU-T G.997.1]. The value and format of this parameter shall be the same as that in Field #12 of O-SIGNATURE (see clause 12.3.3.2.1.1). + +Field #3 "Downstream minimum SNR margin (MINSNRMsds)" is the minimum SNR margin the VTU-R shall tolerate. The definition and use of this parameter shall be the same as for the parameter "Downstream Minimum Noise Margin (MINSNRMsds)" specified in [ITU-T G.997.1]. The field shall be formatted as a 16-bit unsigned integer with LSB weight of 0.1 dB and a valid range between 0 and 31 dB. + +Field #4 "Downstream maximum SNR margin (MAXSNRMds)". The value and format for this parameter shall be the same as in Field #11 of O-SIGNATURE (see clause 12.3.3.2.1.1). + +NOTE – Improper setting of one or more of the following parameters – maximum net data rate, downstream maximum SNR margin, impulse noise protection, maximum interleaving delay (in SNRM\_MODE=1), and TXREFVN (in SNRM\_MODE=2) – can result in high levels of transmit power that can lead to high crosstalk experienced by DSLs on other pairs in the same binder. Specifically, high values of maximum net data rate, downstream maximum SNR margin, impulse noise protection, low values of maximum interleaving delay (in SNRM\_MODE=1), and high values of TXREFVN (in SNRM\_MODE=2) are of concern. + +Field #5 "RA-MODE" specifies the mode of operation of a rate-adaptive VTU-O in the downstream direction as defined in [ITU-T G.997.1]. This field shall be coded as an 8-bit integer with valid values 0116, 0216, 0316 and 0416 for RA-MODE 1, 2, 3 and 4, respectively. + +Field #6 "NTR" shall be set to 0116 if the VTU-O is transporting the NTR signal in the downstream direction, otherwise it shall be set to 0016. + +Field #7 "TPS-TC capabilities" indicates the TPS-TC capabilities of the VTU-O as shown in Table 12-50. + +Field #8 "PMS-TC capabilities" indicates the PMS-TC capabilities of the VTU-O. This includes the supported latency paths at the VTU-O (DS and US) and the capabilities per path (such as supported coding and interleaver parameters), as shown in Table 12-52. + +Field #9 "Downstream Rate adaptation downshift SNR margin (RA-DSNRMds)": The definition and use of this parameter is specified in clause 13.4. The field shall be formatted as a 16-bit unsigned integer with LSB weight of 0.1 dB and has a valid range between 0 and 31.0 dB. + +Field #10 "Downstream Rate adaptation downshift time interval (RA-DTIMEds)": The definition and use of this parameter is specified in clause 13.4. The field shall be formatted as a 16-bit unsigned integer with LSB weight of 1 s and has a valid range between 0 and 16 383 s. + +Field #11 "Downstream Rate adaptation upshift SNR margin (RA-USNRMds)": The definition and use of this parameter is specified in clause 13.4. The field shall be formatted as a 16-bit unsigned integer with LSB weight of 0.1 dB and has a valid range between 0 and 31.0 dB. + +Field #12 "Downstream Rate adaptation upshift time interval (RA-UTIMEds)": The definition and use of this parameter is specified in clause 13.4. The field shall be formatted as a 16-bit unsigned integer with LSB weight of 1 s and has a valid range between 0 and 16 383 s. + +Field #13 indicates the support by the VTU-O of the "Flexible OH Frame Type 2" and INM\_INPEQ\_FORMATds in the downstream direction. The field shall be formatted as [0000 00ba]. The VTU-O shall indicate support by setting, respectively, a=1 and b=1 in this field. Other bits shall be set to 0 and are reserved by ITU-T. + +Field #14 indicates the capabilities of the VTU-O to execute the SOS request in one step or in multiple steps in the downstream direction. The field is formatted as [gggg 0000]. The first four MSBs [gggg] indicate the maximum number of tones (Gsos) that can be executed in a single step in the downstream direction. The valid values are: + +- [0000]: All tones +- [0010]: Gsos = 256 tones +- [0011]: Gsos = 512 tones +- [0100]: Gsos = 1 024 tones + +If SOS is supported, value Gsos = 256 tones is a mandatory capability. If the VTU supports a particular value of Gsos, it shall support all smaller values of Gsos (and values Tsos associated with them, as presented in Table 13-4). + +Each Gsos has a value of Tsos associated with it, where Tsos is the time (in symbols) between the execution of two successive groups of tones (see clause 13.3). + +If the CO does not support SOS in the downstream direction, this field shall contain a value within the specified valid range. This value shall be ignored at the receiver. + +Field #15 indicates the capabilities of the VTU-O to execute the SOS request in one step or in multiple steps in the upstream direction. The format of the field and the valid values shall be the same as for field #14. + +If the CO does not support SOS in the upstream direction, this field shall contain a value within the specified valid range. This value shall be ignored at the receiver. Field #16 Contains the value of the MIN-SOS-BR-ds0 as specified in the MIB. The parameter MIN-SOS-BR-ds0 is defined as the minimum net data rate required for a valid SOS request in the downstream direction (see clause 13.4) for bearer channel 0. The value shall be coded as an unsigned integer representing the data rate as a multiple of 8 kbit/s. + +Field #17 Contains the value of the MIN-SOS-BR-ds1 as specified in the MIB. The parameter MIN-SOS-BR-ds1 is defined as the minimum net data rate required for a valid SOS request in the downstream direction (see clause 13.4) for bearer channel 1. The value shall be coded as an unsigned integer representing the data rate as a multiple of 8 kbit/s. + +When only one bearer channel is supported, the value of Field #16 or Field #17 corresponding to the other bearer channel shall be set to FFFF16. When two bearer channels are supported (as would be the case for dual latency or single latency with two bearer channels mapped into the single latency path) both fields shall contain valid values. + +Field #18 Contains the value of the SOS triggering parameter SOS-TIME-ds as specified in the MIB. The parameter is used in the specification of the receiver initiated SOS (see clause 13.4.3). The special value zero, indicates that the standard SOS triggering criteria are disabled. If the value of this parameter is not zero, the standard SOS triggering criteria are enabled, and the value corresponds with duration of the time window used in the standard SOS triggering criteria. + +The value shall be coded as an unsigned integer representing the duration of the time window as a multiple of 64 ms. The valid range of the non-zero values is from 64 to 16 320 ms. + +Field #19 Contains the value of the SOS triggering parameter SOS-NTONES-ds as specified in the MIB. The parameter is used in the specification of the receiver initiated SOS (see clause 13.4.3). The parameter SOS-NTONES-ds is defined as a percentage of tones. + +The valid range of values is from 0 to 100 in steps of 1. A special value of 0 indicates that SOS-NTONES-ds is not used in the decision criteria. + +Field #20 Contains the value of the SOS triggering parameter SOS-CRC-ds as specified in the MIB. The parameter is used in the specification of the receiver initiated SOS (see clause 13.4.3). + +The valid range of SOS-CRC-ds values is 0.02 to $((2^{16}-1) \times 0.02)$ , in steps of 0.02. + +Field #21 Contains the value of MAX-SOS-ds as specified in the MIB. This parameter contains the maximum allowed number of successful SOS procedures within 120 seconds before the VTU-R shall transition to L3 state (see clause 12.1.4). The valid range of values is from 0 to 15. A special value of 0 indicates that there is no limit on the maximum allowed number of SOS recoveries within this time interval. + +If the CO does not support SOS in the downstream direction, the fields #16 to #21 shall contain a value within the specified valid range for each of the parameters. These values shall be ignored at the receiver. + +Field #22 contains the value of SNRMOFFSET-ROCds as specified in the MIB. The parameter is defined as the SNR Margin offset for the ROC in the downstream direction. This means that the target margin for the ROC is obtained by adding this value to TARSNRM (i.e., $\text{TARSNRM-ROC} = \text{TARSNRM} + \text{SNRMOFFSET-ROC}$ ). + +The parameter TARSNRM-ROC is used in the specification of the channel initialization policy (see clause 12.3.7.1). + +The value shall be coded as an 16 bit unsigned integer with LSB weight of 0.1 dB. The valid range of values is from 0 to 31 dB with 0.1 dB steps. Field #23 contains the value of INPMIN-ROCds expressed in multiples of $T_{4k}$ as specified in the MIB. The value of INPMIN-ROCds expressed in DMT symbols (as to be used by the VTU-R receiver as specified in clause 9.6), is calculated as follows: + +For 4.3125 kHz subcarrier spacing: + +$\text{INPMIN-ROCds in DMT symbols} = \text{INPMIN-ROCds in multiples of } T_{4k}$ . + +For 8.625 kHz subcarrier spacing: + +$\text{INPMIN-ROCds in DMT symbols} = 2 \times (\text{INPMIN-ROCds in multiples of } T_{4k})$ . + +with $T_{4k}$ as defined in clause 10.4.4. + +The parameter INPMIN-ROCds (in DMT symbols) is defined as the required INP\_no\_erasure value for the ROC (see clause 9.6). The value of field #23 is an integer in the range from 0 to 8. + +If the CO does not support a robust overhead channel in the downstream direction, the fields #22 and #23 shall contain a value within the specified valid range for each of the parameters. These values shall be ignored at the receiver. + +Field #24 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #25 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 24 and 25 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +Field #26 control parameter "*REINIT\_TIME\_THRESHOLDS*" contains the threshold for re-initialization based on SES as specified in the CO-MIB, to be used in downstream by the VTU-R receiver when Re-Initialization Policy 1 is used (see clause 12.4.1). The value shall be coded as an unsigned integer representing the maximum number of SES. The valid range is from 5 to 31. + +Field #27 "Time Synchronization capability" indicates the time synchronization capability of the VTU-O. The field shall be coded as a single byte [0000 000t], where: + +- t=0 indicates that time synchronization is not supported; +- t=1 indicates that time synchronization is supported. + +**Table 12-50 – TPS-TC capabilities of the VTU-O** + +| Field name | Format | Description | +|----------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Maximum number of downstream TPS-TCs of each type | 1 byte: [ssaapp00] | Indicates the maximum number of TPS-TCs of each type that the VTU-O supports in the downstream direction:
  • ss=max number of downstream STM TPS-TCs (0,1,2);
  • aa=max number of downstream ATM TPS-TCs (0,1,2); and
  • pp=max number of downstream PTM TPS-TCs (0,1,2)
| +| Maximum number of upstream TPS-TCs of each type | 1 byte: [ssaapp00] | Indicates the maximum number of TPS-TCs of each type that the VTU-O supports in the upstream direction:
  • ss=max number of upstream STM TPS-TCs (0,1,2);
  • aa=max number of upstream ATM TPS-TCs (0,1,2); and
  • pp=max number of upstream PTM TPS-TCs (0,1,2)
| +| Supported combinations of downstream bearer channels and TPS-TCs | 1 byte: [s 0 a 0 p 0 0 s 1 a 1 p 1 0] | s 0 : equal to 1 if STM can be supported on bearer channel 0
a 0 : equal to 1 if ATM can be supported on bearer channel 0
p 0 : equal to 1 if PTM can be supported on bearer channel 0
s 1 : equal to 1 if STM can be supported on bearer channel 1
a 1 : equal to 1 if ATM can be supported on bearer channel 1
p 1 : equal to 1 if PTM can be supported on bearer channel 1 | +| Supported combinations of upstream bearer channels and TPS-TCs | 1 byte: [s 0 a 0 p 0 0 s 1 a 1 p 1 0] | s 0 : equal to 1 if STM can be supported on bearer channel 0
a 0 : equal to 1 if ATM can be supported on bearer channel 0
p 0 : equal to 1 if PTM can be supported on bearer channel 0
s 1 : equal to 1 if STM can be supported on bearer channel 1
a 1 : equal to 1 if ATM can be supported on bearer channel 1
p 1 : equal to 1 if PTM can be supported on bearer channel 1 | +| For each supported TPS-TC, a bearer channel descriptor (see Table 12-51) shall be appended to the message. | | | +| Downstream STM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported downstream STM TPS-TCs. | +| Downstream ATM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported downstream ATM TPS-TCs. | +| Downstream PTM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported downstream PTM TPS-TCs. | +| Upstream STM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported upstream STM TPS-TCs. | +| Upstream ATM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported upstream ATM TPS-TCs. | +| Upstream PTM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported upstream PTM TPS-TCs. | +| NOTE – The number of bearer channel descriptors for the TPS-TC capabilities depends on the fields "Maximum number of downstream/upstream TPS-TCs". | | | + +**Table 12-51 – Bearer channel descriptor** + +| Octet | Content of field | +|-------|------------------------------------------------------------------| +| 1-2 | Minimum net data rate ( net_minn ) | +| 3-4 | Maximum net data rate ( net_maxn ) | +| 5-6 | Reserved net data rate ( net_reserven ) (Note) | +| 7 | Maximum interleaving delay | +| 8 | Impulse noise protection and dynamic interleaver reconfiguration | +| 9 | TPS-TC options | + +NOTE – This parameter is not used in this version of this Recommendation and shall be set to the value of the minimum net data rate in octets 1 and 2. The OLR procedures that utilize this parameter will be defined in a future revision of this Recommendation. + +In the fields "Minimum net data rate", "Maximum net data rate" and "Reserved net data rate", the parameter values for *net\_minn*, *net\_maxn* and *net\_reserven*, respectively, shall be coded as unsigned integers representing the data rate as a multiple of 8 kbit/s. + +The fields "Maximum interleaving delay" and "Impulse noise protection" are not applicable in O-MSG 1 (which communicates capabilities), and the values of octets 7 and 8 in each bearer channel descriptor shall be ignored by the VTU-R receiver. + +The field "TPS-TC options" shall contain one octet to negotiate and select the options for this bearer. The content depends on the type of TPS-TC mapped on this bearer. + +For a bearer mapped to a PTM TPS-TC, the octet shall be coded as follows: + +- Bit 0: If the VTU-O supports pre-emption in this bearer (N.3.1.2 of [ITU-T G.992.3]), the bit shall be set to ONE. +- Bit 1: If the VTU-O supports short packets in this bearer (N.3.1.3 of [ITU-T G.992.3]), the bit shall be set to ONE. +- Bits 2-7 are reserved by ITU-T and set to ZERO. + +For a bearer mapped to an ATM or STM TPS-TC, the TPS-TC options field is reserved by the ITU-T and shall be set to 0016. + +**Table 12-52 – PMS-TC capabilities of the VTU-O** + +| Field name | Format | Description | +|------------------------------------------------|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Downstream OLR capabilities | 1 byte
[rrufdsii] | Indicates the support of optional OLR mechanisms in the downstream direction.
f = 0 if downstream framing reconfiguration (change of $T_p$ , $G_p$ and $B_{p0}$ ) is not supported, f = 1 otherwise (Note 1).
d is reserved by ITU-T for future use and shall be set to ZERO.
s = 0 if downstream SRA (change of $L_p$ , $b_i$ , $g_i$ ) is not supported, s = 1 otherwise.
ii = 00 if interleaver reconfiguration (change of $D_p$ ) is not supported, ii = 01 if interleaver reconfiguration is supported on one downstream latency path, ii = 11 if interleaver reconfiguration is supported on both downstream latency paths (Note 2).
ii = 10 is reserved by the ITU-T.
u = 0 if downstream SOS is not supported, u = 1 otherwise (Notes 3, 4)
rr = 00 indicates that the ROC in the downstream direction is not supported at the VTU-O.
rr = 01 indicates that the ROC in the downstream direction is supported, but dual latency mode is not.
rr = 11 indicates that both the ROC and dual latency mode shall be supported in the downstream direction, but only one of these can be enabled at a given time.
rr = 10 is reserved by the ITU-T. | +| Upstream OLR capabilities | 1 byte
[rrufdsii] | Indicates the support of optional OLR mechanisms in the upstream direction.
f = 0 if upstream framing reconfiguration (change in $T_p$ , $G_p$ and $B_{p0}$ ) is not supported, f = 1 otherwise (Note 1).
d is reserved by ITU-T for future use and shall be set to ZERO.
s = 0 if upstream SRA (change of $L_p$ , $b_i$ , $g_i$ ) is not supported, s = 1 otherwise.
ii = 00 if interleaver reconfiguration (change of $D_p$ ) is not supported, ii = 01 if interleaver reconfiguration is supported on one upstream latency path, ii = 11 if interleaver reconfiguration is supported on both upstream latency paths (Note 2).
ii = 10 is reserved by the ITU-T.
u = 0 if upstream SOS is not supported, u = 1 otherwise (Notes 3, 4)
rr = 00 indicates that the ROC in the upstream direction is not supported at the VTU-O.
rr = 01 indicates that the ROC in the upstream direction is supported, but dual latency mode is not.
rr = 11 indicates that both the ROC and dual latency mode shall be supported in the upstream direction, but only one of these can be enabled at a given time.
rr = 10 is reserved by the ITU-T. | +| Downstream message overhead data rate (Note 5) | 1 byte | Minimum message overhead data rate that is needed by the VTU-O in the downstream direction. The unsigned 8-bit value is the message overhead data rate divided by 1 000 bits per second minus 1 (covering the range 1 to 256 kbit/s). | + +**Table 12-52 – PMS-TC capabilities of the VTU-O** + +| Field name | Format | Description | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Upstream message overhead data rate (Note 5) | 1 byte | Minimum message overhead data rate that is needed by the VTU-O in the upstream direction. The unsigned 8-bit value is the message overhead data rate divided by 1 000 bits per second minus 1 (covering the range 1 to 256 kbit/s). | +| Max DS net data rate for latency path 0 | 2 bytes | Parameter block of 2 octets that describes the maximum downstream net data rate supported in latency path #0. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| Max US net data rate for latency path 0 | 2 bytes | Parameter block of 2 octets that describes the maximum upstream net data rate supported in latency path #0. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| Max DS net data rate for latency path 1 | 2 bytes | Parameter block of 2 octets that describes the maximum downstream net data rate supported in latency path #1. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| Max US net data rate for latency path 1 | 2 bytes | Parameter block of 2 octets that describes the maximum upstream net data rate supported in latency path #1. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| DS (1/S) max | 1 byte | Parameter block of 1 octet that describes the maximum value of 1/S supported by the VTU-O in the downstream direction as defined in clause 9.5.5. The unsigned 8-bit value is coded as 1 to 64 in steps of 1. | +| US (1/S) max | 1 byte | Parameter block of 1 octet that describes the maximum value of 1/S supported by the VTU-O in the upstream direction as defined in clause 9.5.5. The unsigned 8-bit value is coded as 1 to 64 in steps of 1. | +| NOTE 1 – If support for SOS is indicated, support for framing reconfiguration (change of $T_p$ , $G_p$ and $B_{p0}$ ) shall also be indicated. | | | +| NOTE 2 – In the case of single latency mode (i.e., without the ROC), the values for latency path 1 shall be set to ZERO. In the case of single latency with ROC mode, the values for latency path 0 shall be set to ZERO. | | | +| NOTE 3 – If downstream SOS is supported, support for interleaver depth reconfiguration in the downstream direction shall also be indicated. If upstream SOS is supported, support for interleaver depth reconfiguration in the upstream direction shall also be indicated. | | | +| NOTE 4 – If support for SOS is indicated, support for SRA shall also be indicated. | | | +| NOTE 5 – When the ROC is enabled, all overhead data shall be carried in latency path #0 (the ROC). | | | + +### 12.3.5.2.1.2 O-TPS + +The O-TPS message conveys the TPS-TC configuration for both the upstream and the downstream directions. It is based on the capabilities that were indicated in O-MSG 1 and R-MSG 2. The full list of parameters carried by the O-TPS message is shown in Table 12-53. + +**Table 12-53 – Description of message O-TPS** + +| | Field name | Format | +|---|-------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | TPS-TC configuration | See Table 12-54 | +| 3 | Maximum delay variation | See Table 12-55 | +| 4 | ROC and SOS enable | 1 byte | +| 5 | ITU-T G.998.4 parameter field | Variable length | +| 6 | ITU-T G.993.5 parameter field | Variable length | +| 7 | Time synchronization enable | 1 byte | +| 8 | attndr_method | 1 byte | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "TPS-TC configuration" specifies the TPS-TC configuration in the upstream and downstream directions, and is structured as shown in Table 12-54. + +Field #3 "Maximum delay variation" specifies the maximum delay variation for each active bearer channel in the downstream direction, and is structured as shown in Table 12-55. + +Field #4 indicates whether the ROC and SOS are enabled. It is a one byte value [ssss rrrr]. + +The value rrrr shall be coded as follows: + +- A value rrrr=0000 indicates that the ROC is not enabled in either upstream or downstream; +- A value rrrr=0001 indicates that the ROC is enabled in upstream but not in downstream; +- A value rrrr=0010 indicates that the ROC is enabled in downstream but not in upstream; +- A value rrrr=0011 indicates that the ROC is enabled in both upstream and downstream. + +The value ssss shall be coded as follows: + +- A value ssss=0000 indicates that SOS is not enabled; +- A value ssss=0001 indicates that SOS is enabled in upstream but not in downstream; +- A value ssss=0010 indicates that SOS is enabled in downstream but not in upstream; +- A value ssss=0011 indicates that SOS is enabled in both upstream and downstream. + +The value of ssss shall be set in accordance with ITU-T G.997.1 parameters RA-MODEds and RA-MODEus and the OLR capabilities in O-MSG 1 and R-MSG 2. + +**Table 12-54 – TPS-TC configuration** + +| Field name | Format | Description | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Mapped configurations of downstream bearer channels and TPS-TC types (Note 1) | 1 byte: [aaaa bbbb] |

aaaa = TPS-TC type that is mapped to DS bearer channel 0

  • • aaaa=1000: STM-TC
  • • aaaa=0100: ATM-TC
  • • aaaa=0010: PTM-TC
  • • aaaa =0000: inactive bearer channel

bbbb = TPS-TC type that is mapped to DS bearer channel 1

  • • bbbb =1000: STM-TC
  • • bbbb =0100: ATM-TC
  • • bbbb =0010: PTM-TC
  • • bbbb =0000: inactive bearer channel
| +| Mapped configurations of upstream bearer channels and TPS-TC types (Note 1) | 1 byte: [cccc dddd] |

cccc = TPS-TC type that is mapped to US bearer channel 0

  • • cccc =1000: STM-TC
  • • cccc =0100: ATM-TC
  • • cccc =0010: PTM-TC
  • • cccc =0000: inactive bearer channel

dddd = TPS-TC type that is mapped to US bearer channel 1

  • • dddd =1000: STM-TC
  • • dddd =0100: ATM-TC
  • • dddd =0010: PTM-TC
  • • dddd =0000: inactive bearer channel
| +| Downstream rate adaptation ratio | 1 byte | This field contains the rate adaptation ratio of downstream bearer channel 0 as specified in [ITU-T G.997.1]. This field shall be coded as an unsigned integer in the range from 0 to 100. A value of 100 means that the whole excess capacity is allocated to bearer channel 0. | +| For each active bearer channel in each direction, a bearer channel descriptor (see Table 12-51) shall be appended to the message: | | | +| Downstream bearer channel 0 configuration | 0, or 1 bearer channel descriptor | Contains the required configuration of the downstream bearer 0 | +| Downstream bearer channel 1 configuration | 0, or 1 bearer channel descriptor | Contains the required configuration of the downstream bearer 1 | +| Upstream bearer channel 0 configuration | 0, or 1 bearer channel descriptor | Contains the required configuration of the upstream bearer 0 | +| Upstream bearer channel 1 configuration | 0 or 1 bearer channel descriptor | Contains the required configuration of the upstream bearer 1 | +| NOTE 1 – Some simultaneous mappings of TPS-TCs are invalid (see clause 8.1.3.1).
NOTE 2 – The number of bearer channel descriptors for the bearer channel configurations depends on the number of active bearer channels in each direction. | | | + +In each bearer channel descriptor, the fields "Minimum net data rate", "Maximum net data rate" and "Reserved net data rate" shall contain the values for *net\_minn*, *net\_maxn* and *net\_reserven*, + +respectively, selected by the VTU-O. Each shall be coded as an unsigned integer representing the data rate as a multiple of 8 kbit/s. + +In the field "Maximum interleaving delay", the parameter $delay\_max_n$ shall be coded as an unsigned integer expressing delay in ms as follows: + +- The valid values are $0 \leq delay\_max_n \leq 63$ , and $delay\_max_n = 255$ ; +- The value $delay\_max_n = 1$ is a special value indicating that the interleaver depth $D_p$ shall be set to $D_p = 1$ , corresponding to the lowest possible delay; +- The value $delay\_max_n = 0$ is a special value indicating that no bound on the maximum delay is being imposed; +- The value $delay\_max_n = 255$ is a special value indicating an interleaving delay of 1 ms. + +If the bearer channel is operated without physical layer retransmission as defined in [ITU-T G.998.4], then the field "Impulse noise protection and dynamic interleaver reconfiguration" shall be coded as follows: + +- Bits 0-5 shall contain the required $INP\_min_n$ value expressed in DMT symbols; +- The valid values are $0 \leq INP\_min_n \leq 16$ ; +- The value $INP\_min_n = 0$ is a special value indicating that no minimum level of impulse noise protection is required; +- Bit 6 shall be set to 1 to indicate that the bearer should be mapped in a latency path that supports dynamic interleaver reconfiguration. When no latency paths support dynamic interleaver reconfiguration or when the bearer chooses not to use it, the value of this bit shall be ZERO; + +NOTE 1 – For both upstream and downstream transmission, the number of bearer channels that set the value of bit 6 to ONE cannot be higher than the number of latency paths that support interleaver reconfiguration. + +- Bit 7: $INP\_no\_erasure\_required$ (see clause 9.6) + - When set to ONE, it indicates that the VTU-R receiver shall set $INP_p = INP\_no\_erasure_p$ ; + - When set to ZERO, it indicates that the VTU-R receiver is not required to set $INP_p = INP\_no\_erasure_p$ . + +If the bearer channel is operated with physical layer retransmission, as defined in [ITU-T G.998.4], then the field "Impulse noise protection and dynamic interleaver reconfiguration" shall be coded as follows: + +- Bits 0-6 shall contain the required $INP\_min_n$ value expressed in DMT symbols; +- Bit 7 shall be reserved for use by ITU-T and shall be set to ZERO. + +NOTE 2 – Improper setting of one or more of the following parameters – maximum net data rate, downstream maximum SNR margin, impulse noise protection, maximum interleaving delay (in SNRM\_MODE=1), TXREFVN (in SNRM\_MODE=2 and SNRM\_MODE=4), RXREFVN (in SNRM\_MODE=3 and SNRM\_MODE=4), and TXREFVNSF and RXREFVNSF (in SNRM\_MODE=4) can result in high levels of transmit power that can lead to high crosstalk experienced by DSLs on other pairs in the same binder. Specifically, high values of maximum net data rate, downstream maximum SNR margin, impulse noise protection, low values of maximum interleaving delay (in SNRM\_MODE=1), and high values of TXREFVN (in SNRM\_MODE=2 and SNRM\_MODE=4), RXREFVN (in SNRM\_MODE=3 and SNRM\_MODE=4), and TXREFVNSF and RXREFVNSF (in SNRM\_MODE=4) are of concern. + +The field "TPS-TC options" shall be coded as follows: + +- Bit 0: The bit shall be set to ONE to enable pre-emption in this bearer, if and only if the bit was set to ONE for this bearer in both O-MSG 1 and R-MSG 2; + +- Bit 1: The bit shall be set to ONE to enable short packets in this bearer, if and only if the bit was set to ONE for this bearer in both O-MSG 1 and R-MSG 2. + +For a bearer mapped to an ATM or STM TPS-TC, bits 0 and 1 of the TPS-TC options field are reserved by ITU-T and shall be set to ZERO. + +For the upstream bearer channel(s), bits 2-7 shall be set to ZERO. + +For the downstream bearer channel(s), bits 2-7 shall be coded as follows: + +- Bits 3-2 contains the selection of the CIpolicy that shall be used in the downstream direction. A value of 002 indicates that the mandatory CIpolicy shall be used. A value of 012 indicates that the optional CIpolicy 1 (see clause 12.3.7) shall be used. A value of 102 indicates that the optional CIpolicy 2 (see clause 12.3.7) shall be used. The CO shall only select optional CIpolicies for which the VTU-R has indicated support (see clause 12.3.5.2.2.1). A value different from 002 can only be selected if no more than one bearer channel is active; +- Bit 4 contains the selection of the Re-Initialization Policy that shall be used in the downstream direction for that bearer channel (*RIpolicydsn*). A value of ZERO indicates that the mandatory Re-Initialization Policy 0 shall be used. A value of ONE indicates that the optional Re-Initialization Policy 1 (see clause 12.1.4) shall be used. The same value shall be indicated for all bearer channels. The CO shall only select optional Re-Initialization Policies for which the VTU-R has indicated support (see clause 12.3.5.2.2.1); +- Bits 5-7 are reserved by the ITU-T and shall be set to ZERO. + +**Table 12-55 – Maximum delay variation** + +| Field name | Format | Description | +|---------------------------------------------------------------------------------------------------------------------------|---------------------|---------------------------------------------------------| +| For each active bearer channel in downstream direction, a maximum delay variation field shall be present in this message: | | | +| Downstream bearer channel 0 DV_max | 0, or 1 byte (Note) | Contains the required DV_max of the downstream bearer 0 | +| Downstream bearer channel 1 DV_max | 0, or 1 byte (Note) | Contains the required DV_max of the downstream bearer 1 | +| NOTE – The number of bytes is 0 if the bearer is disabled and is 1 if the bearer is enabled. | | | + +The fields "Downstream bearer channel 0 DV\_max" and "Downstream bearer channel 1 DV\_max" describe the maximum allowed value for the delay variation and shall be coded as an unsigned integer equal to the DV\_max divided by 0.1 ms. + +- The valid values are $0 \leq DV\_max_n \leq 25.4$ ; +- The value FF16 is a special value indicating that no delay variation bound is imposed. + +Field #5 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #6 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 5 and 6 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +Field #7 "Time Synchronization enable" indicates whether time synchronization is enabled. The field shall be formatted as [0000 00b1b0]. The valid values are: + +- If b1b0=00, time synchronization is not enabled; +- If b1b0=01, frequency synchronization with the PMD sampling clock being frequency locked to the ToD network clock is used for time synchronization; +- If b1b0=10, frequency synchronization via the processing of ToD phase difference values is used for time synchronization; +- b1b0=11 is reserved by ITU-T. + +Field #8 describes which method shall be used for the calculation of ATTNDR in the downstream direction. The field shall be formatted as [0000 00mm]. + +The value mm=00b, respectively 01b, respectively 10b indicates that the VTU-R shall calculate the downstream ATTNDR using *attndr\_method* = 0, respectively 1, respectively 2, as defined in clause 11.4.1.1.7.1, respectively clause 11.4.1.1.7.2. + +The value mm=11b is reserved by the ITU-T. + +### 12.3.5.2.1.3 O-PMS + +The O-PMS message conveys the initial PMS-TC parameter settings that shall be used in the upstream direction during Showtime. It also specifies the portion of shared interleaver memory that the VTU-R can use to de-interleave the downstream data stream. The full list of parameters carried by the O-PMS message is shown in Table 12-56. + +**Table 12-56 – Description of message O-PMS** + +| | Field name | Format | +|----|---------------------------------------------|-------------------------| +| 1 | Message descriptor | Message code | +| 2 | MSGGLP (Note 1) | 1 byte | +| 3 | Mapping of bearer channels to latency paths | 1 byte | +| 4 | B x0 | 1 byte | +| 5 | B x1 | 1 byte | +| 6 | LP 0 (Note 2) | Latency path descriptor | +| 7 | LP 1 | Latency path descriptor | +| 8 | max_delay_octet DS,0 | 3 bytes | +| 9 | max_delay_octet DS,1 | 3 bytes | +| 10 | max_delay_octet US,0 | 3 bytes | +| 11 | max_delay_octet US,1 | 3 bytes | +| 12 | Upstream SOS tone groups | Band descriptor | +| 13 | Upstream ROC parameters | ROC descriptor | +| 14 | ITU-T G.998.4 parameter field | Variable length | +| 15 | ITU-T G.993.5 parameter field | Variable length | +| 16 | ATTNDR_max_delay_octet SDS,p | 3 bytes | + +NOTE 1 – If the ROC is enabled, MSGGLP shall be equal to 0. +NOTE 2 – If the ROC is enabled, the framing parameters for latency path #0 shall be contained in the ROC descriptor. + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "MSGLP" is a one-byte field that indicates which latency path is selected for OH frames of Type 1 (which carries message overhead) in the upstream direction. The seven MSBs of the byte shall always be set to ZERO. The LSB shall be set to ZERO to indicate latency path #0 or ONE to indicate latency path #1. + +Field #3 "Mapping of bearer channels to latency paths" is a one-byte field that indicates which bearer channels shall be carried in each of the upstream latency paths. The byte is denoted as [cccc dddd]. The bits cccc shall be set to 0000 if bearer channel #0 is to be carried in latency path #0, and to 0001 if bearer channel #0 is to be carried in latency path #1. The bits cccc shall be set to 1111 if the bearer channel #0 is disabled. The bits dddd indicate which latency path carries bearer channel #1 using the same encoding method as used for cccc. + +Field #4 "Bx0" is a one-byte field that indicates the number of octets from bearer channel #0 that shall be transported in each MDF in the upstream direction. The value shall be either zero or the non-zero value from the set {B00, B10}. + +Field #5 "Bx1" is a one-byte field that indicates the number of octets from bearer channel #1 that shall be transported in each MDF in the upstream direction. The value shall be either zero or the non-zero value from the set {B01, B11}. + +Field #6 "LP0" is a 10-byte field that contains the PMS-TC parameters for latency path #0 in the upstream direction. The "Latency path descriptor" format specified in Table 12-57 shall be used. + +Field #7 "LP1" is a 10-byte field that contains the PMS-TC parameters for latency path #1 in the upstream direction. The "Latency path descriptor" format specified in Table 12-57 shall be used. If latency path #1 is not used, all bytes of LP1 shall be set to ZERO. + +Field #8 "max\_delay\_octetDS,0" is a 3-byte field that specifies the maximum value of delay\_octetDS,0 (defined in clause 6.2.8), specified in bytes as an unsigned integer. + +Field #9 "max\_delay\_octetDS,1" is a 3-byte field that specifies the maximum value of delay\_octetDS,1 (defined in clause 6.2.8), specified in bytes as an unsigned integer. If the value of this field is set to the special value FFFFFF16, the Field #8 (max\_delay\_octetDS,0) specifies the maximum value of (delay\_octetDS,0 + delay\_octetDS,1) and the VTU-R shall autonomously partition the number of octets between both downstream latency paths. The value FFFFFF16 is not allowed if the VTU intends to use interleaver reconfiguration in the downstream direction. + +Field #10 "max\_delay\_octetUS,0" is a 3-byte field that specifies the maximum value of delay\_octetUS,0 (defined in clause 6.2.8), specified in bytes as an unsigned integer. + +Field #11 "max\_delay\_octetUS,1" is a 3-byte field that specifies the maximum value of delay\_octetUS,1 (defined in clause 6.2.8), specified in bytes as an unsigned integer. + +The values exchanged in Fields #8 to #11 shall be valid during initialization and showtime. In particular, interleaver reconfiguration in a given latency path shall not lead to an interleaver delay that exceeds the values exchanged in O-PMS for that latency path. Any OLR command that results in a delay value that is higher than the one exchange during initialization shall be rejected. + +Field #12 contains the start and stop frequencies of the SOS tone groups (as defined in clause 13.3) for the upstream direction. It shall be formatted as a band descriptor (see Table 12-22), with a maximum of 64 bands. + +If SOS is not enabled in the upstream direction, the band descriptor shall contain zero bands (see Table 12-22) and shall be ignored by the receiver. + +Field #13 specifies the parameters that define the ROC in the upstream direction. It is formatted as an ROC descriptor, as defined in Table 12-58. + +If the ROC is not enabled in the upstream direction, the values in the ROC descriptor shall all be set to zero and shall be ignored by the receiver. + +The latency path descriptor is described in Table 12-57. It contains the primary parameters of the framer, as specified in Table 9-8, and the interleaver settings for one latency path. All values are unsigned integers. + +**Table 12-57 – Latency path descriptor** + +| Octet | Field | Format | Description | +|----------|-------|---------|----------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | T | 1 byte | The number of MDFs in an OH subframe for the latency path; $T = k \times M$ , where $k$ is an integer. The value of $T$ shall not exceed 64. | +| 2 | G | 1 byte | The total number of overhead octets in an OH subframe for the latency path; $1 \leq G \leq 32$ . | +| 3 | F | 1 byte | Number of OH frames in the OH superframe for the latency path. $1 \leq F \leq 255$ . | +| 4 | M | 1 byte | The number of MDFs in an RS codeword for the latency path. Only the values 1, 2, 4, 8, 16 are allowable. | +| 5 and 6 | L | 2 bytes | Contains the value of $L$ for the latency path. | +| 7 | R | 1 byte | Contains the value of $R$ for the latency path. | +| 8 | I | 1 byte | Contains the value of $I$ for the latency path. | +| 9 and 10 | D | 2 bytes | Interleaver depth $D$ for the latency path. | + +**Table 12-58 – ROC descriptor** + +| Octet | Field | Format | Description | +|----------|-------|---------|-----------------------------------------------------------------------------------------------------------------------------------------| +| 1 | T | 1 byte | The number of MDFs in an OH subframe of the ROC. $T = k \times M$ , where $k$ is an integer. The value of $T$ shall not exceed 64. | +| 2 | G | 1 byte | The total number of overhead octets in an OH subframe of the ROC; The valid values of $G$ are $1 \leq G \leq 32$ . | +| 3 | F | 1 byte | Number of OH frames in the OH superframe for the ROC. The value of $F$ shall be 1. | +| 4 | M | 1 byte | The number of MDFs in an RS codeword for the ROC. The valid values of $M$ are 1, 2, 4, 8 and 16. | +| 5 and 6 | L | 2 bytes | Contains the value of $L$ for the ROC. The valid values of $L$ are from 8 to 128 in multiples of 8. | +| 7 | R | 1 byte | Contains the value of $R$ for the ROC. The value of $R$ shall be 16. | +| 8 | I | 1 byte | Contains the value of $I$ for the ROC. $I$ shall be set to $I = M \times (G/T) + R$ . The valid values of $I$ are $32 \leq I \leq 66$ . | +| 9 and 10 | D | 2 bytes | Interleaver depth $D$ for the ROC. The valid values of $D$ are $1 \leq D \leq 20$ . | + +Field #14 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #15 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 14 and 15 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +Field #16 "ATTNDR\_max\_delay\_octetDS,p" is a 3-byte field that specifies the maximum of delay\_octetDS,p that the VTU-R shall assume in the calculation of ATTNDR in downstream, for the latency path carrying the single bearer channel (see clause 11.4.1.1.7.2). The ATTNDR\_max\_delay\_octetDS,p shall be specified in bytes as an unsigned integer. + +#### 12.3.5.2.1.4 O-PMD + +The O-PMD message conveys the initial PMD parameter settings that shall be used in the upstream direction during showtime. The full list of parameters carried by the O-PMD message is shown in Table 12-59. + +**Table 12-59 – Description of message O-PMD** + +| Field name | | Format | +|-------------------------------------------------------------------------------------------|-------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Message descriptor | Message code | +| 2 | Trellis | 1 byte | +| 3 | Bits and gains table | $2 \times NSC_{us}$ bytes | +| 4 | Tone ordering table | $3 \times \lceil NSC_{us}/2 \rceil$ bytes coded as follows:
  • • Bits 0-11: t_{2n-1}
  • • Bits 12-23: t_{2n}
| +| 5 | Initialization status | 1 byte | +| 6 | ITU-T G.998.4 parameter field | Variable length | +| 7 | ITU-T G.993.5 parameter field | Variable length | +| NOTE – The $\lceil x \rceil$ notation represents rounding to the nearest greater integer. | | | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Trellis" indicates whether trellis coding shall be used in the upstream direction (0016 = trellis disabled, 0116 = trellis enabled). + +Field #3 "Bits and gains table" contains the $b_i$ and $g_i$ values for every subcarrier in MEDLEYus. The $b_i$ shall indicate the number of bits to be mapped by the VTU-R to the subcarrier $i$ ; the $g_i$ shall indicate the scale factor that shall be applied to subcarrier $i$ , relative to the gain that was used for that subcarrier during the transmission of R-P-MEDLEY. + +The $b_i$ 's and $g_i$ 's shall only be defined for subcarriers from the MEDLEYus set (as indicated in R-PRM), and shall be sent in ascending order of subcarrier indices $i$ . + +Each $b_i$ value shall be represented as an unsigned 4-bit integer. Each $g_i$ value shall be represented as an unsigned 12-bit fixed-point quantity, with the binary point assumed just to the right of the third most significant bit. For example, a $g_i$ with binary representation (MSB listed first) 001.0100000002 would instruct the VTU-R to scale the constellation for subcarrier $i$ by a gain of 1.25, so that the power of that subcarrier would be 1.94 dB higher than it was during R-P-MEDLEY. + +Each pair of $b_i$ and $g_i$ values shall be mapped on a 16-bit field as follows: [bMbbb gMggg gggg gggg], where bM and gM are the MSBs of the $b_i$ and $g_i$ binary representations, respectively. + +Field #4 "Tone ordering table" contains the tone ordering table $t$ for the upstream direction. The tone ordering table contains the order in which the subcarriers shall be assigned bits in the upstream direction. The table shall include all subcarriers of the MEDLEYus set and only these subcarriers. Each subcarrier index shall be represented as a 12-bit value. Pairs of subcarrier indices shall be mapped to a field of 3 bytes as shown in Table 12-59. For example, if the value of the $n^{\text{th}}$ field is $400200_{16}$ , $t_{2n-1} = 200_{16} = 512$ and $t_{2n} = 400_{16} = 1\,024$ . If the number of subcarriers in the MEDLEYus set is odd, the last 12 bits of the field shall be set to ZERO (and ignored by the receiver). The value of the first index sent shall be equal to the index of the first entry in the tone ordering table ( $t_1$ , see clause 10.3.1). The remaining indices shall be sent in increasing order of the tone ordering table $t$ entries ( $t_2, t_3, \dots, t_{NSCus}$ ). + +Field #5: indicates the "Initialization status". + +If, within the constraints of the channel initialization policies defined in clause 12.3.7, the receiver is unable to select a set of configuration parameters, the "Initialization success/failure code" indicates the initialization failure cause as defined in [ITU-T G.997.1]. If, within the constraints of the channel initialization policies defined in clause 12.3.7, the receiver is able to select a set of configuration parameters, the "Initialization success/failure code" indicates the initialization success. Valid Initialization success/failure codes are as follows: + +- $80_{16}$ : Initialization success; +- $81_{16}$ : Configuration error; +- $82_{16}$ : Configuration not feasible on line; +- $00_{16}$ : Feature not supported. + +Other values are reserved by the ITU-T. + +If an initialization success/failure code $81_{16}$ or $82_{16}$ is set: + +- All values in Field #2 to 4 shall be set to 0; and +- The VTU-O shall return to L3 link state instead of L0 link state at the completion of the initialization procedures. + +Field #6 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #7 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 6 and 7 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-O does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-O does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +### **12.3.5.2.2 VTU-R messages sent during the channel analysis and exchange phase** + +#### **12.3.5.2.2.1 R-MSG 2** + +The R-MSG 2 message conveys VTU-R information to the VTU-O. The full list of parameters carried by the R-MSG 2 message is shown in Table 12-60. + +**Table 12-60 – Description of message R-MSG 2** + +| | Field name | Format | +|----|-----------------------------------------------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | TPS-TC capabilities | See Table 12-61 | +| 3 | PMS-TC capabilities | See Table 12-62 | +| 4 | Support of "Flexible OH frame Type 2" upstream and INM_INPEQ_FORMATds | 1 byte | +| 5 | SOS multi-step activation downstream | 1 byte | +| 6 | SOS multi-step activation upstream | 1 byte | +| 7 | ITU-T G.998.4 parameter field | Variable length | +| 8 | ITU-T G.993.5 parameter field | Variable length | +| 9 | Time synchronization capability | 1 byte | +| 10 | Time synchronization period (TSP) | 1 byte | +| 11 | ATTNDR method capability | 1 byte | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "TPS-TC capabilities" indicates the TPS-TC capabilities of the VTU-R, as shown in Table 12-61. + +Field #3 "PMS-TC capabilities" indicates the PMS-TC capabilities of the VTU-R. This includes the supported latency paths at the VTU-R (DS and US) and the capabilities per path (such as supported coding and interleaver parameters), as shown in Table 12-62. + +Field #4 indicates the support by the VTU-R of the "Flexible OH Frame Type 2" in the upstream direction and the INM\_INPEQ\_FORMATds in the downstream direction. The field shall be formatted as [0000 00ba]. The VTU-R shall indicate support by setting, respectively, a=1 and b=1 in this field. Other bits shall be set to 0 and are reserved by ITU-T. + +Field #5 indicates the capabilities of the VTU-R to execute the SOS request in one step or in multiple steps in the downstream direction. The field is formatted as [gggg 0000]. The first four MSBs [gggg] indicate the maximum number of tones ( $G_{SOS}$ ) that can be executed in a single step in the downstream direction. The valid values are: + +- [0000]: No limitation; +- [0010]: $G_{SOS} = 256$ tones; +- [0011]: $G_{SOS} = 512$ tones; +- [0100]: $G_{SOS} = 1\,024$ tones. + +If SOS is supported, value $G_{SOS} = 256$ tones is a mandatory capability. If the VTU supports a particular value of $G_{SOS}$ , it shall support all smaller values of $G_{SOS}$ (and values $T_{SOS}$ associated with them, as presented in Table 13-4). + +Each $G_{SOS}$ has a value of $T_{SOS}$ associated with it, where $T_{SOS}$ is the time (in symbols) between the execution of two successive groups of tones (see clause 13.3). + +If the CPE does not support SOS in the downstream direction, this field shall contain a value within the specified valid range. This value shall be ignored by the receiver. + +Field #6 indicates the capabilities of the VTU-R to execute the SOS request in one step or in multiple steps in the upstream direction. The format of the field and the valid values shall be the same as for field #5. + +If the CPE does not support SOS in the upstream direction, this field shall contain a value within the specified valid range. This value shall be ignored by the receiver. + +Field #7 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #8 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 7 and 8 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +Field #9 "Time Synchronization capability" indicates the time synchronization capability of the VTU-R. The field shall be coded as a single byte [0000 00pt], where: + +- t=0 indicates that time synchronization is not supported; +- t=1 indicates that time synchronization is supported; +- p = 0 indicates that, if time synchronization is enabled, the ToD phase difference values shall be transported through the OH frame; +- p = 1 indicates that, if time synchronization is enabled, the ToD phase difference values shall be transported through the eoc. + +NOTE – If time synchronization is not supported, then t=0 and the value of p and the contents of field #10 should be ignored by the VTU-O. + +Field #10 indicates the Time Synchronization Period (*TSP*), defined as maximum increment in number of superframes of the $t_1$ instant number contained in two consecutive transmissions of the time synchronization eoc message. *TSP* is represented in one byte with valid values $n = 10 \dots 255$ , indicating $TSP = 16 \times n$ . + +Field #11 indicates the ATTNDR method capability of the VTU-R in the downstream direction. The field shall be formatted as [0000 000m]. + +A value m=1 indicates the VTU-R supports the improved method as defined in clause 11.4.1.1.7.2. + +A value m=0 indicates the VTU-R does not support the improved method, and therefore only supports the basic method as defined in clause 11.4.1.1.7.1. + +Other bits shall be set to 0 and are reserved by ITU-T. + +**Table 12-61 – TPS-TC capabilities of VTU-R** + +| Field name | Format | Description | +|----------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Maximum number of downstream TPS-TCs of each type | 1 byte: [ssaapp00] | Indicates the maximum number of TPS-TCs of each type that the VTU-R supports in the downstream direction:
  • ss=max number of downstream STM TPS-TCs (0,1,2);
  • aa=max number of downstream ATM TPS-TCs (0,1,2); and
  • pp=max number of downstream PTM TPS-TCs (0,1,2).
| +| Maximum number of upstream TPS-TCs of each type | 1 byte: [ssaapp00] | Indicates the maximum number of TPS-TCs of each type that the VTU-R supports in the upstream direction:
  • ss=max number of upstream STM TPS-TCs (0,1,2);
  • aa=max number of upstream ATM TPS-TCs (0,1,2); and
  • pp=max number of upstream PTM TPS-TCs (0,1,2).
| +| Supported combinations of downstream bearer channels and TPS-TCs | 1 byte: [s 0 a 0 p 0 0 s 1 a 1 p 1 0] | s 0 : equal to 1 if STM can be supported on bearer channel 0
a 0 : equal to 1 if ATM can be supported on bearer channel 0
p 0 : equal to 1 if PTM can be supported on bearer channel 0
s 1 : equal to 1 if STM can be supported on bearer channel 1
a 1 : equal to 1 if ATM can be supported on bearer channel 1
p 1 : equal to 1 if PTM can be supported on bearer channel 1 | +| Supported combinations of upstream bearer channels and TPS-TCs | 1 byte: [s 0 a 0 p 0 0 s 1 a 1 p 1 0] | s 0 : equal to 1 if STM can be supported on bearer channel 0
a 0 : equal to 1 if ATM can be supported on bearer channel 0
p 0 : equal to 1 if PTM can be supported on bearer channel 0
s 1 : equal to 1 if STM can be supported on bearer channel 1
a 1 : equal to 1 if ATM can be supported on bearer channel 1
p 1 : equal to 1 if PTM can be supported on bearer channel 1 | +| For each supported TPS-TC, a bearer channel descriptor (see Table 12-51) shall be appended to the message. | | | +| Downstream STM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported downstream STM TPS-TCs. | +| Downstream ATM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported downstream ATM TPS-TCs. | +| Downstream PTM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported downstream PTM TPS-TCs. | +| Upstream STM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported upstream STM TPS-TCs. | +| Upstream ATM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported upstream ATM TPS-TCs. | +| Upstream PTM TPS-TC capabilities | 0, 1, or 2 bearer channel descriptors | Contains the capabilities of the supported upstream PTM TPS-TCs. | +| NOTE – The number of bearer channel descriptors for the TPS-TC capabilities depends on the fields "Maximum number of downstream/upstream TPS-TCs". | | | + +Each bearer channel descriptor (see Table 12-51) shall be coded as follows. + +In the fields "Minimum net data rate", "Maximum net data rate" and "Reserved net data rate", the parameter values for *net\_minn*, *net\_maxn* and *net\_reserven*, respectively, shall be coded as unsigned integers representing the data rate as a multiple of 8 kbit/s. + +The fields "Maximum interleaving delay" and "Impulse noise protection" are not applicable in R-MSG 2 (which communicates capabilities), and the values of octets 7 and 8 in each bearer channel + +descriptor shall be ignored by the VTU-O receiver. + +The field "TPS-TC options" shall be coded as follows: + +- Bit 0: If the VTU-R supports pre-emption in this bearer (N.3.1.2 of [ITU-T G.992.3]), the bit shall be set to ONE; +- Bit 1: If the VTU-R supports short packets in this bearer (N.3.1.3 of ITU-T [G.992.3]), the bit shall be set to ONE. + +For a bearer mapped to an ATM or STM TPS-TC, bits 0 and 1 shall be set to ZERO at the transmitter and ignored by the receiver. + +Bit 2 indicates whether the optional channel initialization policy 1 is supported for that bearer channel. This bit shall be set to ONE to indicate support for this policy. + +Bit 3 indicates whether the optional channel initialization policy 2 is supported for that bearer channel. This bit shall be set to ONE to indicate support for this policy. + +Bit 4 indicates whether the optional Re-Initialization Policy 1 (i.e., $Rlpolicyds_n=1$ ) is supported (see clause 12.1.4) for that bearer channel. This bit shall be set to ONE to indicate support for this policy. This bit shall be set to the same value for all bearer channels. + +Bits 5-7 are reserved by ITU-T and shall be set to ZERO. + +**Table 12-62 – PMS-TC capabilities of VTU-R** + +| Field name | Format | Description | +|-----------------------------|----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Downstream OLR capabilities | 1 byte
[rrufdsii] |

Indicates the support of optional OLR mechanisms in the downstream direction.

f = 0 if downstream framing reconfiguration (change of T_p, G_p and B_{p0}) is not supported, f = 1 otherwise (Note 1).

d is reserved by ITU-T for future use and shall be set to zero.

s = 0 if downstream SRA (change of L_p, b_i, g_i) is not supported, s = 1 otherwise.

ii = 00 if interleaver reconfiguration (change of D_p) is not supported, ii = 01 if interleaver reconfiguration is supported on one downstream latency path, ii = 11 if interleaver reconfiguration is supported on both downstream latency paths (Note 2).

ii = 10 is reserved by the ITU-T.

u = 0 if downstream SOS is not supported, u = 1 otherwise (Notes 3, 4)

rr = 00 indicates that the ROC in the downstream direction is not supported at the VTU-R.

rr = 01 indicates that the ROC in the downstream direction is supported, but dual latency mode is not.

rr = 11 indicates that both the ROC and dual latency mode shall be supported in the downstream direction, but only one of these can be enabled at a given time.

rr = 10 is reserved by the ITU-T.

| + +**Table 12-62 – PMS-TC capabilities of VTU-R** + +| Field name | Format | Description | +|------------------------------------------------|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Upstream OLR capabilities | 1 byte
[rrufdsii] | Indicates the support of optional OLR mechanisms in the upstream direction.
f = 0 if upstream framing reconfiguration (change of $T_p$ , $G_p$ and $B_{p0}$ ) is not supported, f = 1 otherwise (Note 1).
d is reserved by ITU-T for future use and shall be set to zero.
s = 0 if upstream SRA (change of $L_p$ , $b_i$ , $g_i$ ) is not supported, s = 1 otherwise.
ii = 00 if interleaver reconfiguration (change of $D_p$ ) is not supported,
ii = 01 if interleaver reconfiguration is supported on one upstream latency path,
ii = 11 if interleaver reconfiguration is supported on both upstream latency paths (Note 2).
ii = 10 is reserved by the ITU-T.
u = 0 if upstream SOS is not supported, u = 1 otherwise (Notes 3, 4)
rr = 00 indicates that the ROC in the upstream direction is not supported at the VTU-R.
rr = 01 indicates that the ROC in the upstream direction is supported, but dual latency mode is not.
rr = 11 indicates that both the ROC and dual latency mode shall be supported in the upstream direction, but only one of these can be enabled at a given time.
rr = 10 is reserved by the ITU-T. | +| Downstream message overhead data rate (Note 5) | 1 byte | Minimum message overhead data rate that is needed by the VTU-R in the downstream direction. The unsigned 8-bit value is the message overhead data rate divided by 1 000 bits per second minus 1 (covering the range 1 to 256 kbit/s). | +| Upstream message overhead data rate (Note 5) | 1 byte | Minimum message overhead data rate that is needed by the VTU-R in the upstream direction. The unsigned 8-bit value is the message overhead data rate divided by 1 000 bits per second minus 1 (covering the range 1 to 256 kbit/s). | +| Max DS net data rate for latency path 0 | 2 bytes | The maximum downstream net data rate supported in latency path #0. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| Max US net data rate for latency path 0 | 2 bytes | The maximum upstream net data rate supported in latency path #0. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| Max DS net data rate for latency path 1 | 2 bytes | Parameter block of 2 octets that describes the maximum downstream net data rate supported in latency path #1. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| Max US net data rate for latency path 1 | 2 bytes | Parameter block of 2 octets that describes the maximum upstream net data rate supported in latency path #1. The unsigned 16-bit value is the net data rate divided by 8 000 bits per second. | +| DS $(1/S)_{max}$ | 1 byte | Parameter block of 1 octet that describes the maximum value of $1/S$ supported by the VTU-R in the downstream direction as defined in clause 9.5.5. The unsigned 8-bit value is coded as 1 to 64 in steps of 1. | + +**Table 12-62 – PMS-TC capabilities of VTU-R** + +| Field name | Format | Description | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| US (1/S) max | 1 byte | Parameter block of 1 octet that describes the maximum value of 1/S supported by the VTU-R in the upstream direction as defined in clause 9.5.5. The unsigned 8-bit value is coded as 1 to 64 in steps of 1. | +| NOTE 1 – If support for SOS is indicated, support for framing reconfiguration (change of $T_p$ , $G_p$ and $B_{p0}$ ) shall also be indicated.
NOTE 2 – In the case of single latency mode (i.e., without the ROC), the values for latency path 1 shall be set to ZERO. In the case of single latency with ROC mode, the values for latency path 0 shall be set to ZERO.
NOTE 3 – If upstream SOS is supported, support for interleaver depth reconfiguration in the upstream direction shall also be indicated. If downstream SOS is supported, support for interleaver depth reconfiguration in the downstream direction shall also be indicated.
NOTE 4 – If support for SOS is indicated, support for SRA shall also be indicated.
NOTE 5 – When the ROC is enabled, all overhead data shall be carried in latency path #0 (the ROC). | | | + +#### 12.3.5.2.2.2 R-TPS-ACK + +R-TPS-ACK is a message that acknowledges correct reception of the O-TPS message. The content shall be as specified in Table 12-63. + +**Table 12-63 – Description of message R-TPS-ACK** + +| | Field name | Format | +|---|-------------------------------|-----------------| +| 1 | Message descriptor | Message code | +| 2 | ITU-T G.998.4 parameter field | Variable length | +| 3 | ITU-T G.993.5 parameter field | Variable length | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #3 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 2 and 3 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +#### 12.3.5.2.2.3 R-PMS + +The R-PMS message conveys the initial PMS-TC parameter settings that shall be used in the downstream direction during showtime. The full list of parameters carried by the R-PMS message is shown in Table 12-64. + +**Table 12-64 – Description of message R-PMS** + +| | Field name | Format | +|----|---------------------------------------------|-------------------------| +| 1 | Message descriptor | Message code | +| 2 | MSGGLP (Note 1) | 1 byte | +| 3 | Mapping of bearer channels to latency paths | 1 byte | +| 4 | B x0 | 1 byte | +| 5 | B x1 | 1 byte | +| 6 | LP 0 (Note 2) | Latency path descriptor | +| 7 | LP 1 | Latency path descriptor | +| 8 | Erasure decoding used | 1 byte | +| 9 | Downstream SOS tone groups | Band descriptor | +| 10 | Downstream ROC parameters | ROC descriptor | +| 11 | ITU-T G.998.4 parameter field | Variable length | +| 12 | ITU-T G.993.5 parameter field | Variable length | + +NOTE 1 – If the ROC is enabled, MSGGLP shall be equal to 0. +NOTE 2 – If the ROC is enabled, the framing parameters for latency path #0 shall be contained in the ROC descriptor. + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "MSGGLP" is a one-byte field that indicates which latency path is selected for OH frames of Type 1 (which carries message overhead) in the downstream direction. The seven MSBs of the byte shall always be set to ZERO. The LSB shall be set to ZERO to indicate latency path #0 or ONE to indicate latency path #1. + +Field #3 "Mapping of bearer channels to latency paths" is a one-byte field that indicates which bearer channels shall be carried in each of the downstream latency paths. The byte is denoted as [cccc dddd]. The bits cccc shall be set to 0000 if bearer channel #0 is to be carried in latency path #0, and to 0001 if bearer channel #0 is to be carried in latency path #1. The bits cccc shall be set to 1111 if the bearer channel #0 is disabled. The bits dddd indicate which latency path carries bearer channel #1 using the same encoding method as used for cccc. + +Field #4 "Bx0" is a one-byte field that indicates the number of octets from bearer channel #0 that shall be transported in each MDF in the downstream direction. The value shall be either zero or the non-zero value from the set {B00, B10}. + +Field #5 "Bx1" is a one-byte field that indicates the number of octets from bearer channel #1 that shall be transported in each MDF in the downstream direction. The value shall be either zero or the non-zero value from the set {B01, B11}. + +Field #6 "LP0" is a 10-byte field that contains the PMS-TC parameters for latency path #0 in the downstream direction. The "Latency path descriptor" format specified in Table 12-57 shall be used. + +Field #7 "LP1" is a 10-byte field that contains the PMS-TC parameters for latency path #1 in the downstream direction. The "Latency path descriptor" format specified in Table 12-57 shall be used. If latency path #1 is not used, all bytes of LP1 shall be set to ZERO. + +Field #8 "Erasure decoding used" is a 1-byte field that indicates whether the VTU-R is using erasure decoding. The value shall be: + +- 0016 if erasure decoding is not used on any downstream latency path; +- 0116 if erasure decoding is used on downstream latency path #0; + +- $10_{16}$ if erasure decoding is used on downstream latency path #1; or +- $11_{16}$ if erasure decoding is used on both downstream latency paths. + +Field #9 contains the start and stop frequencies of the SOS tone groups (as defined in clause 13.3) for the downstream direction. It shall be formatted as a band descriptor (see Table 12-22), with a maximum of 64 bands. + +If SOS is not activated in the downstream direction, the band descriptor shall contain zero bands (see Table 12-22) and shall be ignored by the receiver. + +Field #10 specifies the parameters that define the ROC in the downstream direction. It is formatted as an ROC descriptor, as defined in Table 12-58. + +If the ROC is not enabled in the downstream direction, the values in the ROC descriptor shall all be set to zero and shall be ignored by the receiver. + +Field #11 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #12 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 11 and 12 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +#### 12.3.5.2.2.4 R-PMD + +The R-PMD message conveys the initial PMD parameter settings that shall be used in the downstream direction during showtime. The content of R-PMD is shown in Table 12-65. + +**Table 12-65 – Description of message R-PMD** + +| | Field name | Format | +|-------------------------------------------------------------------------------------------|-------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Message descriptor | Message code | +| 2 | Trellis | 1 byte | +| 3 | Bits and gains table | $2 \times NSC_{ds}$ bytes | +| 4 | Tone ordering table | $3 \times \lceil NSC_{ds}/2 \rceil$ bytes coded as follows:
  • • Bits 0-11: t_{2n-1}
  • • Bits 12-23: t_{2n}
| +| 5 | Showtime pilot tones | Tone descriptor | +| 6 | Initialization status | 1 byte | +| 7 | ITU-T G.998.4 parameter field | Variable length | +| 8 | ITU-T G.993.5 parameter field | Variable length | +| NOTE – The $\lceil x \rceil$ notation represents rounding to the nearest greater integer. | | | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 "Trellis" indicates whether trellis coding shall be used in the downstream direction ( $00_{16}$ = trellis disabled, $01_{16}$ = trellis enabled). + +Field #3 "Bits and gains table" contains the $b_i$ and $g_i$ values for every subcarrier in MEDLEYds. The $b_i$ shall indicate the number of bits to be mapped by the VTU-O to the subcarrier $i$ ; the $g_i$ shall indicate the scale factor that shall be applied to subcarrier $i$ , relative to the gain that was used for that subcarrier during the transmission of O-P-MEDLEY. + +The $b_i$ 's and $g_i$ 's shall only be defined for subcarriers from the MEDLEYds set (as indicated in O-PRM), and shall be sent in ascending order of the subcarrier indices $i$ . + +Each $b_i$ value shall be represented as an unsigned 4-bit integer. Each $g_i$ value shall be represented as an unsigned 12-bit fixed-point quantity, with the binary point assumed just to the right of the third most significant bit. For example, a $g_i$ with binary representation (MSB listed first) $001.010000000_2$ would instruct the VTU-O to scale the constellation for subcarrier $i$ by a gain of 1.25, so that the power of that subcarrier would be 1.94 dB higher than it was during O-P-MEDLEY. + +Each pair of $b_i$ and $g_i$ values shall be mapped on a 16-bit field as follows: [ $b_{Mbbb}$ $g_{Mggg}$ $gggg$ $gggg$ ], where $b_M$ and $g_M$ are the MSBs of the $b_i$ and $g_i$ binary representations, respectively. + +Field #4 "Tone ordering table" contains the tone ordering table $t$ for the downstream direction. The tone ordering table contains the order in which the subcarriers shall be assigned bits in the downstream direction. The table shall include all subcarriers of the MEDLEYds set and only these subcarriers. Each subcarrier index shall be represented as a 12-bit value. Pairs of subcarrier indices shall be mapped to a field of 3 bytes as shown in Table 12-65. For example, if the value of the $n^{\text{th}}$ field is $400200_{16}$ , $t_{2n-1} = 200_{16} = 512$ and $t_{2n} = 400_{16} = 1\,024$ . If the number of subcarriers in the MEDLEYds set is odd, the last 12 bits of the field shall be set to ZERO (and ignored by the receiver). The value of the first index sent shall be equal to the index of the first entry in the tone ordering table ( $t_1$ , see clause 10.3.1). The remaining indices shall be sent in increasing order of the tone ordering table $t$ entries ( $t_2, t_3, \dots, t_{NSCds}$ ). + +Field #5 "Showtime pilot tones" indicates the selection of pilot tones that the VTU-R intends to use during showtime. The field shall be formatted as a tone descriptor, as shown in Table 12-33. The first octet of the tone descriptor shall contain the number of pilot tones selected by the VTU-R. If this number is zero, there shall be no further octets in the descriptor. If the number of tones is not equal to zero, each group of three consecutive octets in the descriptor shall describe the location (i.e., the subcarrier index) of two pilot tones. If the number of pilot tones is odd, the last 12 bits shall be ignored. + +The VTU-R shall only select a tone as a pilot tone if the bit loading for that tone, as given in the bits and gains table (Field #3), is equal to zero. The showtime pilot tones shall be modulated as specified in clause 10.4.5.1. The total number of showtime pilot tones shall not exceed 16. + +Field #6: indicates the "Initialization status". + +If, within the constraints of the channel initialization policies defined in clause 12.3.7, the receiver is unable to select a set of configuration parameters, the "Initialization success/failure code" indicates the initialization failure cause as defined in [ITU-T G.997.1]. If, within the constraints of the channel initialization policies defined in clause 12.3.7, the receiver is able to select a set of configuration parameters, the "Initialization success/failure code" indicates the initialization success. Valid Initialization success/failure codes are as follows: + +- $80_{16}$ : Initialization success; +- $81_{16}$ : Configuration error; +- $82_{16}$ : Configuration not feasible on line; +- $00_{16}$ : Feature not supported. + +Other values are reserved by the ITU-T. + +If an initialization success/failure code $81_{16}$ or $82_{16}$ is set: + +- all values in Field #2 to 4 shall be set to 0; and + +- the VTU-R shall return to L3 link state instead of L0 link state at the completion of the initialization procedures. + +Field #7 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +Field #8 is a variable length field consisting of an integer number of bytes. It is formatted as shown in Table 12-26. + +The actual data in the variable length fields 5 and 6 are beyond the scope of this Recommendation. For a correct interpretation at the receiver, support of either [ITU-T G.998.4] or [ITU-T G.993.5] or both is required. However, support of those Recommendations is not implied or required for compliance with Recommendation ITU-T G.993.2. + +If the VTU-R does not support [ITU-T G.998.4], the ITU-T G.998.4 parameter field shall be a single byte with value 0. + +If the VTU-R does not support [ITU-T G.993.5], the ITU-T G.993.5 parameter field shall be a single byte with value 0. + +### 12.3.5.3 Signals transmitted during the channel analysis and exchange phase + +All signals transmitted during the channel analysis and exchange phase shall use only subcarriers from the MEDLEYds set in the downstream direction and subcarriers from the MEDLEYus set in the upstream direction. + +The transmit PSD of downstream signals shall comply with the downstream MEDLEY reference PSD mask (MREFMASKds) that was established at the end of the channel discovery phase in both the passband and the stopbands. The values of $2N_{ds}$ and CE shall be those determined at the end of the channel discovery phase and communicated in Fields #7 and #4 in O-PRM, respectively. The values of $\beta_{ds}$ and cyclic prefix length shall be as communicated in Field #6 and Field #5 of O-PRM, respectively. + +The transmit PSD of all upstream signals shall comply with the upstream MEDLEY reference PSD mask (MREFMASKus) that was established at the end of the channel discovery phase in both the passband and the stopbands. The values of $2N_{us}$ and CE shall be those determined at the end of the channel discovery phase and communicated in Field #6 of R-PRM and Field #4 in O-PRM, respectively. The values of $\beta_{us}$ and cyclic prefix length shall be those communicated in Fields #5 and #4 of R-PRM, respectively. + +#### 12.3.5.3.1 Signals transmitted by the VTU-O + +##### 12.3.5.3.1.1 O-P-MEDLEY + +O-P-MEDLEY is used by the VTU-R to estimate the downstream SNR and to communicate the SOC messages specified in clause 12.3.5.2.1. During transmission of O-P-MEDLEY, the SOC is in its active state. + +The duration of O-P-MEDLEY is variable. The VTU-O terminates O-P-MEDLEY by transmitting O-P-SYNCHRO 6. + +O-P-MEDLEY shall use all MEDLEYds subcarriers modulated by 4-QAM. O-P-MEDLEY shall carry either one byte ( $b_7 b_6 \dots b_0$ ) or two bytes ( $b_{15} b_{14} \dots b_0$ ) of information per DMT symbol. The bits shall be mapped to the subcarriers as described in Table 12-66 for two bytes per DMT symbol and in Table 12-67 for one byte per DMT symbol. The number of bytes per DMT symbol shall be the minimum of the values of $B_{ex-ds-O}$ and $B_{ex-ds-R}$ requested by the VTU-O and VTU-R in O-TA\_UPDATE and R-TA\_UPDATE, respectively. + +The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in free-running mode (see clause 12.3.6.2.2). The scrambler shall reset when the VTU-O enters the channel analysis and exchange phase. + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds}+L_{CE}$ samples. The overall window length shall be $\beta_{ds}$ . + +**Table 12-66 – Bit mapping for O-P-MEDLEY with two bytes per DMT symbol** + +| Subcarrier index | Constellation point | +|---------------------------------|----------------------------| +| 5, 10, 15, ..., 5 $n$ , ... | 00 | +| 1, 11, 21, ..., 10 $n$ + 1, ... | SOC message bits 0 and 1 | +| 2, 12, 22, ..., 10 $n$ + 2, ... | SOC message bits 2 and 3 | +| 3, 13, 23, ..., 10 $n$ + 3, ... | SOC message bits 4 and 5 | +| 4, 14, 24, ..., 10 $n$ + 4, ... | SOC message bits 6 and 7 | +| 6, 16, 26, ..., 10 $n$ + 6, ... | SOC message bits 8 and 9 | +| 7, 17, 27, ..., 10 $n$ + 7, ... | SOC message bits 10 and 11 | +| 8, 18, 28, ..., 10 $n$ + 8, ... | SOC message bits 12 and 13 | +| 9, 19, 29, ..., 10 $n$ + 9, ... | SOC message bits 14 and 15 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1, b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +**Table 12-67 – Bit mapping for O-P-MEDLEY with one byte per DMT symbol** + +| Subcarrier index | Constellation point | +|---------------------------------|--------------------------| +| Even | 00 | +| 1, 11, 21, ..., 10 $n$ + 1, ... | SOC message bits 0 and 1 | +| 3, 13, 23, ..., 10 $n$ + 3, ... | SOC message bits 2 and 3 | +| 5, 15, 25, ..., 10 $n$ + 5, ... | SOC message bits 4 and 5 | +| 7, 17, 27, ..., 10 $n$ + 7, ... | SOC message bits 6 and 7 | +| 9, 19, 29, ..., 10 $n$ + 9, ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1, b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +The transmit PSD of the MEDLEYds subcarriers in O-P-MEDLEY shall be equal to the downstream MEDLEY reference PSD (MREFPSDds) communicated in Field #2 of O-PRM. + +#### 12.3.5.3.1.2 O-P-SYNCHRO 6 + +O-P-SYNCHRO 6 is a signal that provides an exact time marker for the transition from O-P-MEDLEY to Showtime. During transmission of O-P-SYNCHRO 6, the SOC is in its inactive state. + +The duration of O-P-SYNCHRO 6 is 15 DMT symbols. + +O-P-SYNCHRO 6 shall use all subcarriers in the MEDLEYds set modulated by 4-QAM. The value 11 shall be mapped to all of the MEDLEYds subcarriers for the first 5 and the last 5 DMT symbols. The value 00 shall be mapped to all of the MEDLEYds subcarriers for the middle 5 DMT symbols. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the + +quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{ds}+L_{CE}$ samples. The overall window length shall be equal to $\beta_{ds}$ . + +The transmit PSD of the MEDLEYds subcarriers in O-P-SYNCHRO 6 shall be the same as for O-P-MEDLEY. + +### 12.3.5.3.2 Signals transmitted by the VTU-R + +#### 12.3.5.3.2.1 R-P-MEDLEY + +R-P-MEDLEY is used by the VTU-O to estimate the upstream SNR and to communicate the SOC messages specified in clause 12.3.5.2.2. During transmission of R-P-MEDLEY, the SOC is in its active state. + +The duration of R-P-MEDLEY is variable. The VTU-R terminates R-P-MEDLEY by transmitting R-P-SYNCHRO 6. + +R-P-MEDLEY shall use all MEDLEYus subcarriers modulated by 4-QAM. R-P-MEDLEY shall carry either one byte ( $b_7 b_6 \dots b_0$ ) or two bytes ( $b_{15} b_{14} \dots b_0$ ) of information per DMT symbol. The bits shall be mapped to subcarriers as described in Table 12-68 for two bytes per DMT symbol and in Table 12-69 for one byte per DMT symbol. The number of bytes per DMT symbol shall be the minimum of the values of $B_{ex-us-O}$ and $B_{ex-us-R}$ requested by the VTU-O and VTU-R in O-TA\_UPDATE and R-TA\_UPDATE, respectively. + +The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in free-running mode (see clause 12.3.6.2.2). The scrambler shall reset when the VTU-R enters the channel analysis and exchange phase. + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us}+L_{CE}$ samples. The overall window length shall be $\beta_{us}$ . + +**Table 12-68 – Bit mapping for R-P-MEDLEY with two bytes per DMT symbol** + +| Subcarrier index | Constellation point | +|------------------------------------|----------------------------| +| $5, 10, 15, \dots, 5n, \dots$ | 00 | +| $1, 11, 21, \dots, 10n + 1, \dots$ | SOC message bits 0 and 1 | +| $2, 12, 22, \dots, 10n + 2, \dots$ | SOC message bits 2 and 3 | +| $3, 13, 23, \dots, 10n + 3, \dots$ | SOC message bits 4 and 5 | +| $4, 14, 24, \dots, 10n + 4, \dots$ | SOC message bits 6 and 7 | +| $6, 16, 26, \dots, 10n + 6, \dots$ | SOC message bits 8 and 9 | +| $7, 17, 27, \dots, 10n + 7, \dots$ | SOC message bits 10 and 11 | +| $8, 18, 28, \dots, 10n + 8, \dots$ | SOC message bits 12 and 13 | +| $9, 19, 29, \dots, 10n + 9, \dots$ | SOC message bits 14 and 15 | + +NOTE – The byte is given as ( $b_7 b_6 b_5 b_4 b_3 b_2 b_1 b_0$ ), where $b_7$ is the MSB and $b_0$ is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value ( $b_1 b_0$ ) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +**Table 12-69 – Bit mapping for R-P-MEDLEY with one byte per DMT symbol** + +| Subcarrier index | Constellation point | +|---------------------------------|--------------------------| +| Even | 00 | +| 1, 11, 21, ..., $10n + 1$ , ... | SOC message bits 0 and 1 | +| 3, 13, 23, ..., $10n + 3$ , ... | SOC message bits 2 and 3 | +| 5, 15, 25, ..., $10n + 5$ , ... | SOC message bits 4 and 5 | +| 7, 17, 27, ..., $10n + 7$ , ... | SOC message bits 6 and 7 | +| 9, 19, 29, ..., $10n + 9$ , ... | 00 | + +NOTE – The byte is given as (b7, b6, b5, b4, b3, b2, b1, b0), where b7 is the MSB and b0 is the LSB. Mapping, e.g., "SOC message bits 0 and 1" to subcarriers $10n+1$ means that the two-bit value (b1, b0) shall be used to determine the constellation point in accordance with the encoding rules given in clause 10.3.3.2. This constellation point will then be scrambled using the quadrant scrambler described in clause 12.3.6.2. + +The transmit PSD of the MEDLEYus subcarriers in R-P-MEDLEY shall be equal to the upstream MEDLEY reference PSD (MREFPSDus) communicated in the Field #2 of R-PRM. + +### 12.3.5.3.2.2 R-P-SYNCHRO 6 + +R-P-SYNCHRO 6 is a signal that provides an exact time marker for the transition from R-P-MEDLEY to Showtime. During transmission of R-P-SYNCHRO 6, the SOC is in its inactive state. + +The duration of R-P-SYNCHRO 6 is 15 DMT symbols. + +R-P-SYNCHRO 6 shall use all subcarriers in the MEDLEYus set modulated by 4-QAM. The value 11 shall be mapped to all of the MEDLEYus subcarriers for the first 5 and the last 5 DMT symbols. The value 00 shall be mapped to all of the MEDLEYus subcarriers for the middle 5 DMT symbols. The constellation points on all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +Symbols shall be generated as described in clause 10.4.4. The symbol length shall be $2N_{us} + L_{CE}$ samples. The overall window length shall be equal to $\beta_{us}$ . + +The transmit PSD of the MEDLEYus subcarriers in R-P-SYNCHRO 6 shall be the same as for R-P-MEDLEY. + +## 12.3.6 General initialization signal requirements + +### 12.3.6.1 Periodic signal requirements + +The periodic signals used in initialization (O-P-PERIODIC 1, R-P-PERIODIC 1, and others) shall meet the requirements specified in this clause. + +Implementers may choose to generate periodic signals using cyclically extended symbols or directly using the $2N$ samples out of the IDFT. The duration of each periodic signal shall be selected by a VTU such that it contains an integer number of cyclically extended symbols and an integer multiple of $2N$ samples. Specifically, $N_{Sym\_CE} \times (2N + L_{CE}) = k \times 2N$ , where $N_{Sym\_CE}$ is the number of cyclically extended symbols needed to construct the periodic signal, and $k$ is the number of periodic symbols in the periodic signal. + +To ensure a smooth transition from an initialization signal with cyclically extended symbols to one that is periodic, the first symbol of each periodic signal shall be prepended by a cyclic prefix of $\beta$ samples, where $\beta = \beta_{ds}$ for downstream signals and $\beta = \beta_{us}$ for upstream signals. These $\beta$ samples shall be windowed and overlapped with the last $\beta$ samples of the last symbol of the previous signal, as described in clause 10.4.4. Likewise, to ensure a smooth transition from a periodic signal to a signal + +using cyclically extended symbols, the last $\beta$ samples of the last symbol in the periodic signal shall be windowed and overlapped with the first $\beta$ samples of the first symbol of the next signal. + +### 12.3.6.2 Quadrant scrambler + +The constellation point of each subcarrier shall be pseudo-randomly rotated by $0$ , $\pi/2$ , $\pi$ or $3\pi/2$ depending on the value of a 2-bit pseudo-random number. The subcarrier with index 0 (DC) shall not be rotated. The rotation shall be implemented by transforming the $(X, Y)$ coordinates of the constellation point as shown in Table 12-70, where $X$ and $Y$ are the coordinates before scrambling. + +**Table 12-70 – Pseudo-random transformation** + +| $d_{2n}, d_{2n+1}$ | Angle of rotation | Final coordinates | +|--------------------|-------------------|-------------------| +| 0 0 | 0 | $(X, Y)$ | +| 0 1 | $\pi/2$ | $(-Y, X)$ | +| 1 1 | $\pi$ | $(-X, -Y)$ | +| 1 0 | $3\pi/2$ | $(Y, -X)$ | + +The 2-bit values shown in the first column of Table 12-70 shall be the output of a PRBS generator defined by the equation: + +$$d_n = d_{n-9} \oplus d_{n-11}$$ + +The bit generator is illustrated in Figure 12-12. + +![Figure 12-12 – Bit generator diagram. It shows a sequence of delay blocks labeled d_{n-1}, d_{n-2}, ..., d_{n-9}, d_{n-10}, d_{n-11}. The input enters from the left and splits: one path goes directly to an output labeled d_n, and the other path passes through the delay blocks. The output of the d_{n-11} block is fed into an XOR gate (represented by a circle with a plus sign). The other input to the XOR gate is the direct input path. The output of the XOR gate is fed back into the input of the d_{n-1} block. A small label 'G.993.2(15)_F 12-12' is present in the bottom right corner of the diagram area.](357536e18f2ad306db16dc51ab0bb30b_img.jpg) + +Figure 12-12 – Bit generator diagram. It shows a sequence of delay blocks labeled d\_{n-1}, d\_{n-2}, ..., d\_{n-9}, d\_{n-10}, d\_{n-11}. The input enters from the left and splits: one path goes directly to an output labeled d\_n, and the other path passes through the delay blocks. The output of the d\_{n-11} block is fed into an XOR gate (represented by a circle with a plus sign). The other input to the XOR gate is the direct input path. The output of the XOR gate is fed back into the input of the d\_{n-1} block. A small label 'G.993.2(15)\_F 12-12' is present in the bottom right corner of the diagram area. + +**Figure 12-12 – Bit generator** + +Two bits from the scrambler shall be mapped to each subcarrier, including DC. The two bits corresponding to DC shall be overwritten with 00. + +For a VDSL2 system that uses an IDFT size = $2N$ , $2N$ bits shall be generated by the scrambler every DMT symbol ( $b_0 b_1 b_2 \dots b_{2N-2} b_{2N-1}$ ) in each transmission direction. The first two bits ( $b_0 b_1$ ) shall correspond to subcarrier 0, the next two bits ( $b_2 b_3$ ) to subcarrier 1, and so on; bits ( $b_{2i} b_{2i+1}$ ) shall correspond to subcarrier $i$ . Bits shall be generated for all subcarriers, not just those being transmitted. Bits generated for subcarriers that are not in use shall be discarded. + +At the beginning of initialization, all registers of the scrambler shall be set to ONE. Two modes of scrambler operation are used: reset mode and free-running mode. + +#### 12.3.6.2.1 Reset mode + +In reset mode, the scrambler shall be reset at the beginning of every symbol period. Therefore, the same $2N$ bits will be generated for each symbol, and each subcarrier will be assigned the same two-bit pseudo-random number for rotation of its constellation point in successive symbols. + +### 12.3.6.2.2 Free-running mode + +In free-running mode, the scrambler shall not be reset at the beginning of each symbol period, but instead shall continue running from one symbol to the next. As a result, there should be no correlation between the two bits that are mapped on subcarrier $i$ during symbol $s$ and the two bits mapped to subcarrier $i$ during symbol $s+1$ . To guarantee that the bits on a particular subcarrier are uncorrelated from one DMT symbol to the next, for all values of IDFT size, four scrambler bits shall be skipped between symbols $s$ and $s+1$ . Practically, this means the scrambler generates $2N$ bits that are allocated to symbol $s$ . The next four bits generated by the scrambler are not used. The next $2N$ bits from the scrambler are then allocated to symbol $s+1$ . + +### 12.3.7 Channel initialization policies + +The method used by the receiver to select the values of transceiver parameters described in this clause is implementation dependent. However, within the limit of the total data rate provided by the local PMD, the selected values shall meet all of the constraints communicated by the transmitter prior to the channel analysis and exchange phase, including: + +- Message overhead data rate $\geq$ Minimum message overhead data rate; +- Net data rate $\geq$ Minimum net data rate for all bearer channels; +- Impulse noise protection $\geq$ Minimum impulse noise protection for all bearer channels; +- Delay $\leq$ Maximum delay for all bearer channels; +- SNR Margin $\geq$ TARSNRM. + +Within those constraints, the receiver shall select the values as to optimize in the priority given in one of the priority lists below, where the selection of the list is configured through the CO-MIB channel initialization policy parameter (CIPOLICY, see clause 7.3.2.10 of [ITU-T G.997.1]). The channel initialization policy applies only for the selection of the values exchanged during initialization, and does not apply during showtime. + +Due to use of the specific modulation pattern of O/R-P-MEDLEY signal (modulation with SOC bytes followed by a quadrant scrambler), after the VTU enters the SHOWTIME state, the reported SNRM value can be inaccurate and lower than the TARSNRM value. + +If OLR type 3 (SRA) is supported and enabled, the VTU may initiate an SRA with vendor discretionary triggering criteria for a period of 10 seconds after the VTU has entered the SHOWTIME state in order to achieve a more accurate reported SNRM value greater than or equal to the TARSNRM value. + +The following channel initialization policies are defined: + +- Policy ZERO if $Cipolicy_n=0$ , then: + - 1) Maximize net data rate for all bearer channels, per the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 12.3.5). + - 2) Minimize excess margin with respect to the maximum SNR margin (MAXSNRM) through gain adjustments (see clause 10.3.4.2). Other control parameters may be used to achieve this (e.g., MAXMASK, see clause 7.2.3). +- Policy ONE if $Cipolicy_n=1$ , then: + - a) If the minimum net data rate (see clause 7.3.2.1.1 of [ITU-T G.997.1]) is set equal to the maximum net data rate (see clause 7.3.2.1.3 of [ITU-T G.997.1]) then + - 1) Maximize $INP\_act_n$ for bearer channel $\#n$ . + - b) If the minimum net data rate (see clause 7.3.2.1.1 of [ITU-T G.997.1]) is not set equal to the maximum net data rate (see clause 7.3.2.1.3 of [ITU-T G.997.1]) then + +- 1) Maximize net data rate for all the bearer channels, per the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 12.3.5). + - 2) If such maximized net data rate is equal to the maximum net data rate (see clause 7.3.2.1.3 of [ITU-T G.997.1]), maximize $INP\_act_n$ for the bearer channel # $n$ . + - 3) Minimize excess margin with respect to the maximum noise margin MAXSNRM through gain scalings (see clause 10.3.4.2). Other control parameters may be used to achieve this (e.g., MAXMASK, see clause 7.2.3). +- Policy TWO if $CIPolicy_n = 2$ , then: + - 1) Maximize net data rate for all the bearer channels, per the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 12.3.5). + - 2) If such maximized net data rate is equal to the maximum net data rate (see clause 7.3.2.1.3 of [ITU-T G.997.1]), maximize $SNRM_n$ for the bearer channel # $n$ . + - 3) Minimize excess margin with respect to the maximum noise margin MAXSNRM through gain scalings (see clause 10.3.4.2). Other control parameters may be used to achieve this (e.g., MAXMASK, see clause 7.2.3). + +If only a single bearer channel is configured through the CO-MIB, then the CIPOLICY shall be set to ZERO, ONE or TWO. If multiple bearer channels are configured through the CO-MIB, then the CIPOLICY shall be set to ZERO for each of the bearer channels. The use of the channel initialization policy ONE or TWO with multiple bearer channels is for further study. + +Support of channel initialization policy ZERO is mandatory. Support of channel initialization policy ONE or TWO is optional. Additional channel initialization policies are for further study. The $CIPolicy_n$ parameter values other than 0, 1 and 2 are reserved for use by the ITU-T. + +### 12.3.7.1 Channel initialization policies with ROC + +The method used by the receiver to select the values of transceiver parameters described in this clause is implementation dependent. However, within the limit of the total data rate provided by the local PMD, the selected values shall meet all of the constraints communicated by the transmitter prior to the channel analysis and exchange phase, including: + +- Message overhead data rate $\geq$ Minimum message overhead data rate; +- Net data rate $\geq$ Minimum net data rate for all bearer channels; +- Impulse noise protection $\geq$ Minimum impulse noise protection for all bearer channels; +- Delay $\leq$ Maximum delay for all bearer channels; +- SNR Margin $\geq$ TARSNRM; +- SNR Margin for the ROC $\geq$ TARSNRM. + +Within those constraints, the receiver shall select the values as to optimize in the priority given in one of the priority lists below, where the selection of the list is configured through the CO-MIB channel initialization policy parameter (CIPOLICY, see clause 7.3.2.10 of [ITU-T G.997.1]). The channel initialization policy applies only for the selection of the values exchanged during initialization and does not apply during SHOWTIME. + +Due to use of the specific modulation pattern of O/R-P-MEDLEY signal (modulation with SOC bytes followed by a quadrant scrambler), after the VTU enters the SHOWTIME state, the reported SNRM-ROC value can be inaccurate and lower than the TARSNRM value. + +If OLR type 3 (SRA) is supported and enabled, the VTU may initiate an SRA with vendor discretionary triggering criteria for a period of 10 seconds after the VTU has entered the SHOWTIME state in order to achieve a more accurate reported SNRM-ROC value greater than or equal to the TARSNRM value, preferably up to TARSNRM-ROC, as defined in the channel initialization policy below. + +The following channel initialization policy is defined: + +- Policy ZERO if $CIpolicy_n=0$ , then: + - 1) Maximize the SNR Margin for the ROC up to TARSNRM-ROC. + - 2) Maximize net data rate for all bearer channels, per the allocation of the net data rate, in excess of the sum of the minimum net data rates over all bearer channels (see clause 12.3.5). + - 3) Maximize the SNR Margin for the ROC above TARSNRM-ROC. + - 4) Minimize excess margin with respect to the maximum SNR margin MAXSNRM through gain adjustments (see clause 10.3.4.2). Other control parameters may be used to achieve this (e.g., MAXMASK, see clause 7.2.3). + +Support of channel initialization policy ZERO is mandatory. Additional channel initialization policies are for further study. The $CIpolicy_n$ parameter values other than 0 are reserved for use by the ITU-T. + +## 12.4 Loop diagnostic mode procedures + +### 12.4.1 Overview + +The built-in loop diagnostic function defined in this clause enables the immediate measurement of channel conditions at both ends of the loop without dispatching maintenance technicians to attach test equipment to the loop. The resulting information helps to isolate the location (inside the premises, near the customer end of the loop, or near the network end of the loop) and the sources (crosstalk, radio frequency interference, and bridged taps) of impairments. + +The loop diagnostic mode shall be entered after completion of the ITU-T G.994.1 handshake phase, when the loop diagnostic mode codepoint in the MS message is set (see clauses 12.3.2.1.2 and 12.3.2.2.2). Loop diagnostic mode shall be entered upon request by either VTU. Both VTUs shall support the loop diagnostic mode. + +The sequence of stages in the loop diagnostic mode shall be the same as for initialization (defined in clause 12.3) up to the channel analysis and exchange phase, where the test parameters listed in Table 12-71 and defined in clause 11.4.1 are exchanged. However, the test parameters for the quiet line noise (QLN) and the channel characteristics function (Hlog) shall be measured and exchanged during the channel discovery phase, as described in clause 12.4.3. + +The time-outs specified in clause 12.3.1 do not apply to loop diagnostic mode. Time-out values are for further study. + +**Table 12-71 – Test parameters exchanged during the loop diagnostic mode** + +| Abbreviation | Name | +|------------------------------------|-----------------------------------------------------------| +| $Hlin(k \times G \times \Delta f)$ | Channel characteristics per subcarrier group, linear | +| $Hlog(k \times G \times \Delta f)$ | Channel characteristics per subcarrier group, $\log_{10}$ | +| $QLN(k \times G \times \Delta f)$ | Quiet line noise per subcarrier group | +| $SNR(k \times G \times \Delta f)$ | Signal-to-noise ratio per subcarrier group | +| LATN-pb | Loop attenuation per band | +| SATN-pb | Signal attenuation per band | +| SNRM-pb | Signal-to-noise ratio margin per band | +| ATTNDR | Attainable net data rate | +| ACTATP | Actual aggregate transmit power (far-end) | + +The test parameters are mapped to messages using an integer number of octets per parameter value. + +In case the parameter value as defined in clause 11.4.1 is represented by a number of bits that is not an integer number of octets, the parameter value shall be mapped to the LSBs of the message octets. Unused more significant bits shall be set to ZERO for unsigned parameter values and shall be set to the sign bit for signed parameter values. + +#### 12.4.1.1 SOC message mapping during loop diagnostic mode + +In order to increase the robustness of the messages exchanged during the channel discovery and training phases of the loop diagnostic mode, all SOC messages shall be sent using 1 information bit per DMT symbol, where each bit is sent 5 times in 5 consecutive DMT symbols. The mapping of the SOC bits to subcarriers during loop diagnostic mode shall be as summarized in Table 12-72. + +**Table 12-72 – Bit mapping during loop diagnostic mode** + +| Subcarrier index | Constellation bits for
SOC bit = 0 | Constellation bits for
SOC bit = 1 | +|-------------------------------|---------------------------------------|---------------------------------------| +| Even | 00 | 00 | +| 1, 11, 21, ..., $10n+1$ , ... | 00 | 11 | +| 3, 13, 23, ..., $10n+3$ , ... | 00 | 11 | +| 5, 15, 25, ..., $10n+5$ , ... | 00 | 11 | +| 7, 17, 27, ..., $10n+7$ , ... | 00 | 11 | +| 9, 19, 29, ..., $10n+9$ , ... | 00 | 00 | + +When the SOC is inactive, the symbols shall be transmitted as described in clause 12.3.3 without modification. + +#### 12.4.2 Channel discovery and training phases of loop diagnostic mode + +##### 12.4.2.1 SOC messages exchanged during the channel discovery and training phases of loop diagnostic mode + +Other than O-PRM and R-PRM, the SOC messages for the channel discovery phase and the training phase of the loop diagnostic mode shall be the same as for the initialization procedure described in clauses 12.3.3 and 12.3.4, respectively. The test parameters for the quiet line noise (QLN) and the channel characteristics function (Hlog) shall be measured and exchanged during the channel discovery phase in the O-PRM-LD and R-PRM-LD messages, which replace O-PRM and R-PRM. The test parameters are listed in Table 12-73 and defined in clause 11.4.1. + +**Table 12-73 – Test parameters exchanged during the channel discovery phase in loop diagnostic mode** + +| Abbreviation | Name | +|--------------------------------------|--------------------------------------------------| +| Hlog( $k \times G \times \Delta f$ ) | Channel characteristics per subcarrier group, dB | +| QLN( $k \times G \times \Delta f$ ) | Quiet line noise per subcarrier group, dBm/Hz | + +##### 12.4.2.1.1 VTU-O message O-PRM-LD + +**Table 12-74 – Description of message O-PRM-LD** + +| | Field name | Format | +|---|---------------------------------------------|----------------| +| 1 | Message descriptor | Message code | +| 2 | Downstream MEDLEY reference PSD (MREFPSDds) | PSD descriptor | + +**Table 12-74 – Description of message O-PRM-LD** + +| | Field name | Format | +|----|------------------------------------------------------------------------------------------------|----------------------| +| 3 | MEDLEYds set | Bands descriptor | +| 4 | Cyclic extension length | 1 byte | +| 5 | Downstream cyclic prefix length | 2 bytes | +| 6 | Downstream transmit window length ( $\beta_{ds}$ ) | 1 byte | +| 7 | VTU-O IDFT size | 1 byte | +| 8 | Duration of the VTU-O EC training period | 1 byte | +| 9 | Requested duration of the VTU-O TEQ training period | 1 byte | +| 10 | Requested duration of the VTU-R TEQ training period | 1 byte | +| 11 | Requested minimum duration of the periodic signal | 1 byte | +| 12 | Downstream frequency-domain spectrum shaping | Log_tssi descriptor | +| 13 | Quiet line noise per subcarrier group, $QLN(k \times G \times \Delta f)$ | 512 bytes | +| 14 | Channel characteristics function Hlog per subcarrier group, $Hlog(k \times G \times \Delta f)$ | $2 \times 512$ bytes | + +Fields #1 to #12 shall be formatted the same as O-PRM (see clause 12.3.3.2.1.3). + +Field #13 "Quiet line noise per subcarrier group, $QLN(k \times G \times \Delta f)$ " indicates the parameter QLN for 512 subcarrier groups in the upstream direction (measured at the VTU-O receiver). The parameter QLN for each group shall be represented as an 8-bit value as specified in clause 11.4.1.1.2, mapped to a single octet. The octets representing QLN values for different groups shall be mapped to Field #13 so that they are transmitted in ascending order of group index $k$ , for $k = 0$ to 511. The groups shall be formed as specified in clause 11.4.1. + +Field #14 "Channel characteristics function Hlog per subcarrier, $Hlog(k \times G \times \Delta f)$ " indicates the parameter Hlog for 512 subcarrier groups in the upstream direction. The parameter Hlog for each group shall be represented as a 10-bit value as specified in clause 11.4.1.1.1, mapped to 2 octets by adding six MSBs equal to 0. The pairs of octets representing Hlog values for different groups shall be mapped to Field #14 so that they are transmitted in ascending order of group index $k$ , for $k = 0$ to 511. The groups shall be formed as specified in clause 11.4.1. + +#### 12.4.2.1.2 VTU-R message R-PRM-LD + +**Table 12-75 – Description of message R-PRM-LD** + +| | Field name | Format | +|---|-----------------------------------------------------|------------------| +| 1 | Message descriptor | Message code | +| 2 | Upstream MEDLEY reference PSD (MREFPSDus) | PSD descriptor | +| 3 | MEDLEYus set | Bands descriptor | +| 4 | Upstream cyclic prefix length | 2 bytes | +| 5 | Upstream transmit window length ( $\beta_{us}$ ) | 1 byte | +| 6 | VTU-R IDFT size | 1 byte | +| 7 | Duration of the VTU-R EC training period | 1 byte | +| 8 | Requested duration of the VTU-R TEQ training period | 1 byte | +| 9 | Requested duration of the VTU-O TEQ training period | 1 byte | + +**Table 12-75 – Description of message R-PRM-LD** + +| | Field name | Format | +|----|------------------------------------------------------------------------------------------|----------------------| +| 10 | Requested minimum duration of the periodic signal | 1 byte | +| 11 | Minimum duration of the R-P-TRAINING 1 signal ( $T_{MIN-R-P-Train}$ ) | 1 byte | +| 12 | Upstream frequency-domain shaping | Log_tss; descriptor | +| 13 | Quiet line noise per subcarrier, $QLN(k \times G \times \Delta f)$ | 512 bytes | +| 14 | Channel characteristics function Hlog per subcarrier, $Hlog(k \times G \times \Delta f)$ | $2 \times 512$ bytes | + +Fields #1 to #12 shall be formatted the same as R-PRM (see clause 12.3.3.2.2.3). + +Field #13 "Quiet line noise per subcarrier group, $QLN(k \times G \times \Delta f)$ " indicates the parameter QLN for 512 subcarrier groups in the downstream direction (measured at the VTU-R receiver). The parameter QLN for each group shall be represented as an 8-bit value as specified in clause 11.4.1.1.2, mapped into a single octet. The octets representing QLN values for different groups shall be mapped to Field #13 so that they are transmitted in ascending order of group index $k$ , for $k = 0$ to 511. The groups shall be formed as specified in clause 11.4.1. + +Field #14 "Channel characteristics function Hlog per subcarrier, $Hlog(k \times G \times \Delta f)$ " indicates the parameter Hlog for 512 subcarrier groups in the downstream direction. The parameter Hlog for each group shall be represented as a 10-bit value as specified in clause 11.4.1.1.1, mapped into 2 octets by adding six MSBs equal to 0. The pairs of octets representing Hlog values for different groups shall be mapped to Field #14 so that they are transmitted in ascending order of group index $k$ , for $k = 0$ to 511. The groups shall be formed as specified in clause 11.4.1. + +#### 12.4.2.2 Signals transmitted during the channel discovery and training phases + +The signals transmitted during the channel discovery and training phases are the same as defined in initialization (see clauses 12.3.3 and 12.3.4) with the following exceptions: + +- The SOC message mapping shall be as defined in clause 12.4.1.1; +- The duration of O-P-QUIET 1 shall be at least 8 192 symbols but not longer than 16 384 symbols. + +#### 12.4.3 Channel analysis and exchange phase of loop diagnostic mode + +Figure 12-13 presents the timing diagram for the stages of the channel analysis and exchange phase of the loop diagnostic mode. It gives an overview of the sequence of signals transmitted and the sequence of SOC messages sent by the VTU-O and VTU-R during the channel analysis and exchange phase of the loop diagnostic mode. The shaded areas correspond to periods of time when the SOC is in its inactive state. + +![Timing diagram for the stages of the channel analysis and exchange phase of the loop diagnostic mode. The diagram is split into Downstream (left) and Upstream (right) sections. Downstream shows VTU-O transmitting O-P-MEDLEY, O-P-SYNCHRO 6, O-P-TRAINING 3, and O-P-SYNCHRO 7 signals, with corresponding SOC messages (O-IDLE, O-MSG-LD). Upstream shows VTU-R transmitting R-P-MEDLEY, R-P-SYNCHRO 6, R-P-TRAINING 3, and R-P-SYNCHRO 7 signals, with corresponding SOC messages (R-IDLE, R-MSG-LD). Vertical arrows on both sides indicate the 'Channel analysis and exchange phase of the loop diagnostic mode (VTU-O)' and '(VTU-R)'.](7ac0d7b4763471d7c6dee8a2ce125b6a_img.jpg) + +The diagram illustrates the timing for channel analysis and exchange in a loop diagnostic mode, divided into Downstream (VTU-O) and Upstream (VTU-R) phases. + +**Downstream (VTU-O) Phases:** + +- SOC Messages:** O-IDLE, (blank), O-IDLE, O-MSG-LD, O-IDLE, (blank). +- Signals:** O-P-MEDLEY, O-P-SYNCHRO 6, (blank), O-P-TRAINING 3, (blank), O-P-SYNCHRO 7. + +**Upstream (VTU-R) Phases:** + +- Signals:** R-P-MEDLEY, (blank), R-P-SYNCHRO 6, (blank), R-P-TRAINING 3, (blank), R-P-SYNCHRO 7. +- SOC Messages:** (blank), R-IDLE, (blank), R-IDLE, R-MSG-LD, R-IDLE, (blank). + +Vertical arrows on the left and right sides of the diagram indicate the duration of the "Channel analysis and exchange phase of the loop diagnostic mode (VTU-O)" and "(VTU-R)" respectively. + +Timing diagram for the stages of the channel analysis and exchange phase of the loop diagnostic mode. The diagram is split into Downstream (left) and Upstream (right) sections. Downstream shows VTU-O transmitting O-P-MEDLEY, O-P-SYNCHRO 6, O-P-TRAINING 3, and O-P-SYNCHRO 7 signals, with corresponding SOC messages (O-IDLE, O-MSG-LD). Upstream shows VTU-R transmitting R-P-MEDLEY, R-P-SYNCHRO 6, R-P-TRAINING 3, and R-P-SYNCHRO 7 signals, with corresponding SOC messages (R-IDLE, R-MSG-LD). Vertical arrows on both sides indicate the 'Channel analysis and exchange phase of the loop diagnostic mode (VTU-O)' and '(VTU-R)'. + +**Figure 12-13 – Timing diagram for the stages of the channel analysis and exchange phase of the loop diagnostic mode** + +Upon entering this phase the VTU-O shall transmit 80 000 DMT symbols of O-P-MEDLEY with O-IDLE being sent over the SOC. Upon entering this phase the VTU-R shall transmit 80 000 DMT symbols of R-P-MEDLEY with R-IDLE being sent over the SOC. + +O-P-MEDLEY and R-P-MEDLEY shall be followed by O-P-SYNCHRO 6 and R-P-SYNCHRO 6, respectively. O-P-SYNCHRO 6 and R-P-SYNCHRO 6 shall be as defined in clause 12.3.5.3. + +After transmitting O-P-SYNCHRO 6, the VTU-O shall transmit O-P-TRAINING 3. While transmitting O-P-TRAINING 3, the VTU-O shall send O-IDLE over the SOC for at least 256 DMT symbols, and shall then send O-MSG-LD. Similarly, after transmitting R-P-SYNCHRO 6, the VTU-R shall transmit R-P-TRAINING 3. While transmitting R-P-TRAINING 3, the VTU-R shall send R-IDLE over the SOC. The VTU-R shall acknowledge the reception of O-MSG-LD by sending R-MSG-LD. Both VTUs shall use the RQ mode, as specified in clause 12.2.2.2. + +The VTU-O shall acknowledge the reception of R-MSG-LD by transmitting O-P-SYNCHRO 7, which also indicates that the VTU-O has completed the channel analysis and exchange phase. The VTU-R acknowledges O-P-SYNCHRO 7 by transmitting R-P-SYNCHRO 7, indicating full completion of the loop diagnostic mode. + +**Table 12-76 – VTU-O signals and SOC messages in the channel analysis and exchange phase of loop diagnostic mode** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages and IDLE flags | SOC state | +|----------------|--------------|----------------------------------------|-----------------------------|-------------| +| O-P-MEDLEY | Non-periodic | 80 000 | O-IDLE | Active | +| O-P-SYNCHRO 6 | Non-periodic | 15 | None | Inactive | +| O-P-TRAINING 3 | Non-periodic | Variable | O-MSG-LD | Active (RQ) | +| O-P-SYNCHRO 7 | Non-periodic | 15 | None | Inactive | + +**Table 12-77 – VTU-R signals and SOC messages during the channel analysis and exchange phase of loop diagnostic mode** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages and IDLE flags | SOC state | +|----------------|--------------|----------------------------------------|-----------------------------|-------------| +| R-P-MEDLEY | Non-periodic | 80 000 | R-IDLE | Active | +| R-P-SYNCHRO 6 | Non-periodic | 15 | None | Inactive | +| R-P-TRAINING 3 | Non-periodic | Variable | R-MSG-LD | Active (RQ) | +| R-P-SYNCHRO 7 | Non-periodic | 15 | None | Inactive | + +#### **12.4.3.1 SOC messages exchanged during the channel analysis and exchange phase of loop diagnostic mode** + +##### **12.4.3.1.1 VTU-O messages** + +In the loop diagnostic mode, the VTU-O shall send the O-MSG-LD message containing the upstream test parameters defined in clause 11.4.1. + +The information fields of O-MSG-LD shall be as shown in Table 12-78. + +**Table 12-78 – Description of message O-MSG-LD** + +| | Field name | Format | +|---|------------------------------------|--------------------------| +| 1 | Message descriptor | Message code | +| 2 | $Hlin(k \times G \times \Delta f)$ | $6 \times 512$ | +| 3 | $SNR(k \times G \times \Delta f)$ | 512 | +| 4 | LATN-pb | $(2 \times 5)$ bytes | +| 5 | SATN-pb | $(2 \times 5)$ bytes | +| 6 | SNRM and SNRM-pb | $2 + (2 \times 5)$ bytes | +| 7 | ATTNDR | 4 bytes | +| 8 | ACTATP | 2 bytes | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 " $Hlin(k \times G \times \Delta f)$ " indicates the parameter Hlin for 512 subcarrier groups in the upstream direction. The parameter Hlin for each group shall be mapped to 6 octets as $[scale\ a(k)\ b(k)]$ , where *scale*, *a(k)*, and *b(k)* are 16-bit values as specified in clause 11.4.1.1.1. The 6 octets representing Hlin values for different groups shall be mapped to Field #2 so that they are transmitted in ascending order of group index *k*, for *k* = 0 to 511. The groups shall be formed as specified in clause 11.4.1. + +Field #3 " $SNR(k \times G \times \Delta f)$ " indicates the parameter SNR for 512 subcarrier groups in the upstream direction. The SNR for each group shall be represented as an 8-bit value as specified in clause 11.4.1.1.3, and mapped into 1 octet. The octets representing SNR values for different groups shall be mapped to Field #3 so that they are transmitted in ascending order of group index *k*, for *k* = 0 to 511. The groups shall be formed as specified in clause 11.4.1. The values of SNR for the groups containing at least one subcarrier that is not in the MEDLEYus set shall be set to FF16. + +Field #4 "LATN-pb" shall indicate the parameter LATN\_U(*m*) for each of 5 potentially available upstream bands. The parameter LATN\_U(*m*) for each band shall be represented as a 10-bit value as specified in clause 11.4.1.1.4, and mapped into 2 octets by adding six MSBs equal to 0. The pairs of octets representing LATN\_U(*m*) values for different bands shall be mapped to Field #4 as described in Table 11-29. The value 000016 shall be used to indicate disabled bands. Octets indicated as reserved in Table 11-29 shall be set to ZERO in the transmitter and ignored by the receiver. + +Field #5 "SATN-pb" shall indicate the parameter SATN\_U(*m*) for each of 5 potentially available upstream bands. The parameter SATN\_U(*m*) for each band shall be represented as a 10-bit value as specified in clause 11.4.1.1.5, and mapped into 2 octets by adding six MSBs equal to 0. The pairs of octets representing SATN\_U(*m*) values for different bands shall be mapped to Field #5 as described in Table 11-29. The value 000016 shall be used to indicate disabled bands. Octets indicated as reserved in Table 11-29 shall be set to ZERO in the transmitter and ignored by the receiver. + +Field #6 "SNRM and SNRM-pb" shall indicate the overall upstream SNRM value, as specified in clause 11.4.1.1.6.2, and parameter SNRM\_U(*m*), as specified in clause 11.4.1.1.6.3. The first two octets shall indicate parameter SNRM and the rest of the octets shall indicate parameter SNRM\_U(*m*) for each of 5 potentially available upstream bands. The value of SNRM shall be represented as a 10-bit value as specified in clause 11.4.1.1.6.2. The parameter SNRM\_U(*m*) for each band shall be represented as a 10-bit value as specified in clause 11.4.1.1.6.3. Both SNRM and SNRM\_U(*m*) shall be mapped into 2 octets by adding six MSBs equal to the sign bit of the SNRM or SNRM\_U(*m*) 10-bit representations, respectively. The pairs of octets representing SNRM\_U(*m*) values for different bands shall be mapped to Field #6 as described in Table 11-29. The value 000016 shall be used to indicate disabled bands. Octets indicated as reserved in Table 11-29 shall be set to ZERO in the transmitter and ignored by the receiver. + +Field #7 "ATTNDR" shall indicate the parameter ATTNDR in the upstream direction computed as specified in clause 11.4.1.1.7 for all subcarriers from the MEDLEYus set. The parameter shall be represented as a 32-bit value as defined in clause 11.4.1.1.7. + +Field #8 "ACTATP" shall indicate the parameter ACTATP in the upstream direction computed as specified in clause 11.4.1.1.8 for all subcarriers from the MEDLEYus set. The parameter shall be represented as a 10-bit value as defined in clause 11.4.1.1.8 and mapped to the 2-byte Field #8 by adding six MSBs equal to the sign bit of the ACTATP representation. + +#### 12.4.3.1.2 VTU-R messages + +In the loop diagnostic mode, the VTU-R shall send the R-MSG-LD message containing the downstream test parameters defined in clause 11.4.1. + +The information fields of R-MSG-LD shall be as shown in Table 12-79. + +**Table 12-79 – Description of message R-MSG-LD** + +| | Field name | Format | +|---|------------------------------------|--------------------------| +| 1 | Message descriptor | Message code | +| 2 | $Hlin(k \times G \times \Delta f)$ | $6 \times 512$ | +| 3 | $SNR(k \times G \times \Delta f)$ | 512 | +| 4 | LATN-pb | $(2 \times 5)$ bytes | +| 5 | SATN-pb | $(2 \times 5)$ bytes | +| 6 | SNRM and SNRM-pb | $2 + (2 \times 5)$ bytes | +| 7 | ATTNDR | 4 bytes | +| 8 | ACTATP | 2 bytes | + +Field #1 "Message descriptor" is a unique one-byte code that identifies the message. See Table 12-6 for a complete list of codes. + +Field #2 " $Hlin(k \times G \times \Delta f)$ " indicates the parameter Hlin for 512 subcarrier groups in the downstream direction. The parameter Hlin for each group shall be mapped into 6 octets as $[scale\ a(k)\ b(k)]$ , where *scale*, *a(k)*, and *b(k)* are 16-bit values as specified in clause 11.4.1.1.1. The 6 octets representing Hlin values for different groups shall be mapped to Field #2 so that they are transmitted in ascending order of group index *k*, for *k* = 0 to 511. The groups shall be formed as specified in clause 11.4.1. + +Field #3 " $SNR(k \times G \times \Delta f)$ " indicates the parameter SNR for 512 subcarrier groups in the downstream direction. The SNR for each group shall be represented as an 8-bit value as specified in clause 11.4.1.1.3, and mapped into a single octet. The octets representing SNR values for different groups shall be mapped to Field #3 so that they are transmitted in ascending order of group index *k*, for *k* = 0 to 511. The groups shall be formed as specified in clause 11.4.1. The values of SNR for the groups containing at least one subcarrier that is not in MEDLEYds set shall be set to FF16. + +Field #4 "LATN-pb" shall indicate the parameter LATN\_D(*m*) for each of 5 potentially available downstream bands. The parameter LATN\_D(*m*) for each band shall be represented as a 10-bit value as specified in clause 11.4.1.1.4, and mapped into 2 octets by adding six MSBs equal to 0. The pairs of octets representing LATN\_D(*m*) values for different bands shall be mapped to Field #4 as described in Table 11-29. The value 000016 shall be used to indicate the disabled bands. Octets indicated as reserved in Table 11-29 shall be set to ZERO in the transmitter and ignored by the receiver. + +Field #5 "SATN-pb" shall indicate the parameter $SATN\_D(m)$ for each of 5 potentially available downstream bands. The parameter $SATN\_D(m)$ for each band shall be represented as a 10-bit value as specified in clause 11.4.1.1.5, and mapped into 2 octets by adding six MSBs equal to 0. The pairs of octets representing $SATN\_D(m)$ values for different bands shall be mapped to Field #5 as described in Table 11-29. The value $0000_{16}$ shall be used to indicate the disabled bands. Octets indicated as reserved in Table 11-29 shall be set to ZERO in the transmitter and ignored by the receiver. + +Field #6 "SNRM and SNRM-pb" shall indicate the overall downstream SNRM value, as specified in clause 11.4.1.1.6.2, and the parameter $SNRM\_D(m)$ , as specified in clause 11.4.1.1.6.3. The first two octets shall indicate parameter SNRM, and the rest of the octets shall indicate parameter $SNRM\_D(m)$ for each of 5 potentially available downstream bands. The value of SNRM shall be represented as a 10-bit value as specified in clause 11.4.1.1.6.2. The value of $SNRM\_D(m)$ for each band shall be represented as a 10-bit value as specified in clause 11.4.1.1.6.3. Both SNRM and $SNRM\_D(m)$ shall be mapped into 2 octets by adding six MSBs equal to the sign bit of the SNRM and $SNRM\_D(m)$ 10-bit representation, respectively. The pairs of octets representing $SNRM\_D(m)$ values for different bands shall be mapped to Field #6 as described in Table 11-29. The value $0000_{16}$ shall be used to indicate the disabled bands. Octets indicated as reserved in Table 11-29 shall be set to ZERO in the transmitter and ignored by the receiver. + +Field #7 "ATTNDR" shall indicate the parameter ATTNDR in the downstream direction computed as specified in clause 11.4.1.1.7 for all subcarriers from the MEDLEYds set. The parameter shall be represented as a 32-bit value as defined in clause 11.4.1.1.7. + +Field #8 "ACTATP" shall indicate the parameter ACTATP in the downstream direction computed as specified in clause 11.4.1.1.8 for all subcarriers from the MEDLEYds set. The parameter shall be represented as a 10-bit value as defined in clause 11.4.1.1.8 and mapped into the 2-byte Field #8 by adding six MSBs equal to the sign bit of the ACTATP representation. + +#### 12.4.3.2 Signals transmitted during the channel analysis and exchange phase of loop diagnostic mode + +The O-P-MEDLEY and R-P-MEDLEY signals shall be as defined in clause 12.3.5.3 for initialization with the following exceptions: + +- the duration of O-P-MEDLEY and R-P-MEDLEY shall each be 80 000 symbols; and +- the SOC message mapping shall be as defined in clause 12.4.1.1. + +O-P-SYNCHRO 6, R-P-SYNCHRO 6, O-P-SYNCHRO 7 and R-P-SYNCHRO 7 shall be as defined in clause 12.3.5.3 for initialization. + +##### 12.4.3.2.1 O-P-TRAINING 3 + +The O-P-TRAINING 3 signal is used to send the O-MSG-LD SOC message. During transmission of O-P-TRAINING 3, the SOC is in its active state. + +The duration of O-P-TRAINING 3 is variable. The VTU-O terminates O-P-TRAINING 3 by transmitting O-P-SYNCHRO 7. + +O-P-TRAINING 3 shall be composed of all subcarriers in the MEDLEYds set. These subcarriers shall be modulated by 4-QAM with SOC bit mapping as described in clause 12.4.1.1. + +The constellation points of all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +The symbol length shall be $2N_{ds}+L_{CE}$ samples. Windowing shall be applied at the transmitter, and the overall window length shall be equal to $\beta_{ds}$ (see clause 10.4.4). The values of $2N_{ds}$ , $L_{CE}$ , $\beta_{ds}$ and cyclic prefix length shall be set to the values communicated by the VTU-O in O-PRM-LD. + +The transmit PSD of the MEDLEYds subcarriers in O-P-TRAINING 3 shall be the same as for O-P-TRAINING 2. + +#### 12.4.3.2.2 R-P-TRAINING 3 + +The R-P-TRAINING 3 signal is used to send the R-MSG-LD SOC message. During transmission of R-P-TRAINING 3, the SOC is in its active state. + +The duration of R-P-TRAINING 3 is variable. The VTU-O terminates R-P-TRAINING 3 by transmitting R-P-SYNCHRO 7. + +R-P-TRAINING 3 shall be composed of all subcarriers in the MEDLEYus set. These subcarriers shall be modulated by 4-QAM with SOC bit mapping as described in clause 12.4.1.1. + +The constellation points of all subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler, as described in clause 12.3.6.2. The scrambler shall be used in reset mode (see clause 12.3.6.2.1). + +The symbol length shall be $2N_{us}+L_{CE}$ samples. Windowing shall be applied at the transmitter, and the overall window length shall be equal to $\beta_{us}$ (see clause 10.4.4). The values of $2N_{us}$ , $\beta_{us}$ and cyclic prefix length shall be set to the values communicated by the VTU-R in R-PRM-LD. The value of $L_{CE}$ shall be as communicated by the VTU-O in O-PRM-LD. + +The transmit PSD of the MEDLEYus subcarriers in R-P-TRAINING 3 shall be the same as for R-P-TRAINING 2. + +### 12.5 Fast start-up + +For further study. + +## 13 On-line reconfiguration (OLR) + +On-line reconfiguration allows changes to the PMD without interruption of service and without errors. The defined procedures for on-line reconfiguration of the PMD function provide means for adapting to slowly varying channel conditions. They provide transparency to the PMS-TC, TPS-TC and higher layers by providing means for configuration parameter changes that introduce no transport errors, no latency changes, and no interruption of service. + +### 13.1 Types of on-line reconfiguration + +Types of OLR include bit swapping, SRA, and SOS. + +Bit swapping reallocates bits and power (i.e., margin) among the allowed subcarriers without modification of the higher layer features of the physical layer. Bit swapping reconfigures the bit and gain ( $b_i$ , $g_i$ ) parameters without changing any other PMD or PMS-TC control parameters. After a bit swapping reconfiguration, the total data rate $(\sum L_p) \times f_s$ is unchanged, and the total data rate on each latency path ( $L_p \times f_s$ ) is unchanged. + +Because bit swapping is used autonomously to maintain the operating conditions of the VTU during changing environment conditions, bit swapping is a mandatory capability. The procedure for bit swapping is defined in clause 11.2.3.3 (OLR commands) and shall be implemented using Type 1 OLR messages as shown in Tables 11-5 and 11-6. + +NOTE – When the ROC is enabled, bits $L_0$ and $L_1$ do not share the same subcarrier (see clause 10.3.1). + +SRA is used to reconfigure the total data rate ( $\sum L_p$ ) by modifying the framing parameters ( $L_p$ ) and modifications to the bits and fine gains ( $b_i$ , $g_i$ ) parameters. Since the total data rate is modified, at least one latency path (or more) will have a new data rate ( $L_p$ ) after the SRA. Since SRA is optional, the ability to support it is identified during the initialization procedure. The procedure for SRA is defined in clause 11.2.3.3 (OLR commands) and shall be implemented using Type 3 OLR messages as shown in Tables 11-6 and 11-7. + +Save our showtime (SOS) provides the receiver with a means to rapidly perform a bit loading reduction in a specified part of the frequency spectrum. This can be used in case of sudden noise increases. During initialization, the VTUs may define a number of SOS tone groups in both the upstream and downstream directions. An SOS request reduces the bit loading on all tones in a group by the same number of bits (multiple groups can be changed in a single command). The SOS request can also explicitly reconfigure the framing parameters $L_p$ and the interleaver depth $D_p$ in each of the latency paths. + +NOTE 1 – For a wideband sudden noise increase, it is a goal that VTUs improve the data transmission within 1 second after the SOS trigger to achieve a $\text{BER} \leq 1\text{E-}7$ . The desired data rate after this time is at least 80% of the data rate that would be obtained if the VTU were to (re-) initialize in the high noise condition using the same Transmit PSD level. + +NOTE 2 – Sudden noise increases of up to 30 dB may occur in real networks. + +Interleaver reconfiguration (within SRA) allows to dynamically change the interleaver depth $D_p$ on one or more latency paths. SRA may be accompanied by a change of the framing parameters $T_p$ , $G_p$ and $B_{p0}$ . Interleaver reconfiguration and modification of framing parameters $T_p$ , $G_p$ and $B_{p0}$ are optional. + +The procedure for interleaver reconfiguration is defined in clauses 9.4.1 and 11.2.3.3 (OLR commands) and shall be implemented using Type 3 OLR messages as shown in Tables 11-6 and 11-7. + +## 13.2 Control parameters + +### 13.2.1 Control parameters controlled by the OLR procedures + +On-line reconfiguration of the PMD is accomplished by a coordinated change to the bits and gain values on two or more subcarriers. The bit and gain parameters described in Table 13-1 may be changed through on-line reconfiguration within the limits described. + +**Table 13-1 – Reconfigurable control parameters of the PMD function** + +| Parameter | Definition | +|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $b_i$ | The number of bits per subcarrier with valid values all integers in the [0 ... 15] range. A change of the $b_i$ values may be performed without modifying the L value (e.g., bit swap) or with a change of the $L$ value (e.g., seamless rate adaptation). | +| $g_i$ | The subcarrier gain adjustments with valid values in the [-14.5 ... +2.5] dB range. | + +The receiver shall support all valid $b_i$ values and shall support increment and decrement of $b_i$ values in steps of 1 bit in the OLR procedures. Incrementing or decrementing by steps larger than 1 bit are optional. + +NOTE – The support of $b_i = 0$ is mandatory for the receiver in order to meet the requirement of $10^{-7}$ bit error ratio specified in clause 9.8. + +The transmitter shall support of all valid values of $b_i$ and shall support increment and decrement of $b_i$ values in any step in the OLR procedures. + +The updated bits and gains table shall comply with the bits and gains table requirements listed in clauses 10.3.1 and 10.3.4. + +On-line reconfiguration of the PMS-TC is accomplished by a coordinated change to the value of one or more of the framing parameters shown in Table 13-2. The framing parameters displayed in Table 13-2 may be changed through on-line reconfiguration within the limits described. + +**Table 13-2 – Reconfigurable framing parameters of the PMS-TC function** + +| Parameter | Definition | +|-----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $L_p$ | If latency path # $p$ is used, the number of bits from latency path # $p$ transmitted in each DMT symbol may be increased or decreased; the value of $L_p$ is determined by the total data rate assigned for the latency path. | +| $D_p$ | The interleaver depth on latency path $p$ may be increased or decreased, as long as the resulting interleaver delay on that latency path does not exceed the bounds determined during initialization. | +| $T_p$ | The number of MDFs in an overhead subframe: This value can be increased or decreased within the set of valid values (see Table 9-8). | +| $G_p$ | The total number of overhead octets in an OH subframe: This value can be increased or decreased within the set of valid values (see Table 9-8). | +| $B_{p0}$ | The total number of octets from bearer channel #0 in a mux data frame: This value can be increased or decreased within the set of valid values (see Table 9-8). | + +NOTE – Any change in $L_p$ , $T_p$ , $G_p$ , and $B_{p0}$ values shall be such that the length of the MDF (as defined in Table 9-8) remains unchanged for all active latency paths. + +### 13.2.2 Parameters controlling the OLR procedures + +The list of parameters controlling OLR procedure Type 3 is presented in Table 13-3. + +**Table 13-3 – Control parameters controlling the OLR procedures** + +| Parameter | Definition | +|------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| RA-USNRM
RA-UTIME |

The rate adaptation upshift noise margin and time interval (defined in [ITU-T G.997.1]). The parameter can be different for the VTU-O (RA-USNRMus and RA-UTIMEus) and the VTU-R (RA-UTIMEds, RA-USNRMds).

VTU-O: Configured through CO-MIB.

VTU-R: Configured through CO-MIB and communicated to the VTU-R during initialization (O-MSG 1).

The valid values for RA-USNRMus and RA-USNRMds are values between 0 and 31.0 dB in steps of 0.1 dB.

The valid values for RA-UTIMEus and RA-UTIMEds are values between 0 and 16 383 s in steps of 1 s.

| +| RA-DSNRM
RA-DTIME |

The rate adaptation downshift noise margin and time interval (defined in [ITU-T G.997.1]). The parameter can be different for the VTU-O (RA-DSNRMus and RA-DTIMEus) and the VTU-R (RA-DTIMEds, RA-DSNRMds).

VTU-O: Configured through the CO-MIB.

VTU-R: Configured through the CO-MIB and communicated to the VTU-R during initialization (O-MSG 1).

The valid values for RA-DSNRMus and RA-DSNRMds are values between 0 and 31.0 dB in steps of 0.1 dB.

The valid values for RA-DTIMEus and RA-DTIMEds are values between 0 to 16 383 s in steps of 1 s.

| + +**Table 13-3 – Control parameters controlling the OLR procedures** + +| Parameter | Definition | +|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $DVmax_n$ |

The maximum allowed value for the delay variation DV_n of bearer channel #n.

It ranges from 0.1 to 25.4 in steps of 0.1 ms.

The value 25.5 indicates that no delay variation bound is imposed.

The parameter can be different for the VTU-O and the VTU-R.

VTU-O: Configured through the CO-MIB.

VTU-R: Configured through the CO-MIB and communicated to the VTU-R during initialization (O-TPS).

| + +### 13.3 Timing of changes in subcarrier configuration + +In both the upstream and the downstream directions, the reconfiguration of the PMD functions shall take effect starting with the tenth symbol that follows transport of the Syncflag for OLR Type 1. As defined in clause 10.2, the sync symbol is transmitted after every 256 data symbols. The reconfiguration of the PMD function shall take effect starting with the symbol at symbol count 9 in the next DMT superframe, where the first symbol in each DMT superframe is the symbol at symbol count 0. + +For OLR Type 3, when performed in the latency path $p$ , the change in $L_p$ values and $b_i, g_i$ values shall take effect starting from the 66th symbol that follows the Syncflag, i.e., the symbol with symbol count 65 in the DMT superframe following the Syncflag, where the first symbol in the DMT superframe is the symbol at symbol count 0. + +The change of framing parameters $T_p, G_p$ and $B_{p0}$ shall take effect on the first OH frame of the first OH superframe that follows the 66th DMT symbol after the Syncflag. + +The change in $D_p$ shall take effect on the first byte of an interleaved RS codeword (byte $k$ as defined in clause 9.4.1). This codeword shall be determined as follows: + +- For a decrease in interleaver depth, this shall be the first RS codeword that starts at or after the beginning of the 66th DMT symbol. +- For an increase in interleaver depth, this shall be the last RS codeword that starts at or before the beginning of the 66th DMT symbol. + +The location of the RS codeword relative to the 66th DMT symbol is illustrated in Figure 13-1. + +![Figure 13-1: Finding the byte where the change in Dp is activated. The diagram shows a sequence of symbols starting with 'Sync', followed by symbols 0, 1, 2, ..., 64, 65. A horizontal arrow labeled Lp spans symbols 1 and 2. A horizontal arrow labeled '65 Lp/8 - ΔNFECp bytes' spans from the start of symbol 1 to the start of symbol 65. Below the symbols, a sequence of bytes is shown: ΔNFECp, NFECp, ..., NFECp, NFECp. Vertical arrows indicate 'Increase in D' and 'Decrease in D'. The 'Increase in D' arrow points to the formula ΔNP + [ (65Lp/8 - ΔNFECp) / NFECp ] * NFECp. The 'Decrease in D' arrow points to the formula ΔNFECp + [ (65Lp/8 - ΔNFECp) / NFECp ] * NFECp. The text G.993.2(15)_F13-1 is at the bottom right.](49a6a2f291a53db753faa3d3faf30cdd_img.jpg) + +Figure 13-1 illustrates the timing and byte location for activating a change in the interleaver depth $D_p$ . The top part shows a sequence of DMT symbols: Sync, 0, 1, 2, ..., 64, 65. A horizontal arrow labeled $L_p$ spans symbols 1 and 2. Another horizontal arrow labeled $65 L_p/8 - \Delta N_{FECp}$ bytes spans from the start of symbol 1 to the start of symbol 65. The bottom part shows a sequence of bytes: $\Delta N_{FECp}$ , $N_{FECp}$ , ..., $N_{FECp}$ , $N_{FECp}$ . Vertical arrows indicate 'Increase in D' and 'Decrease in D'. The 'Increase in D' arrow points to the formula $\Delta N_p + \left[ \frac{65 L_p/8 - \Delta N_{FECp}}{N_{FECp}} \right] * N_{FECp}$ . The 'Decrease in D' arrow points to the formula $\Delta N_{FECp} + \left[ \frac{65 L_p/8 - \Delta N_{FECp}}{N_{FECp}} \right] * N_{FECp}$ . The text G.993.2(15)\_F13-1 is at the bottom right. + +Figure 13-1: Finding the byte where the change in Dp is activated. The diagram shows a sequence of symbols starting with 'Sync', followed by symbols 0, 1, 2, ..., 64, 65. A horizontal arrow labeled Lp spans symbols 1 and 2. A horizontal arrow labeled '65 Lp/8 - ΔNFECp bytes' spans from the start of symbol 1 to the start of symbol 65. Below the symbols, a sequence of bytes is shown: ΔNFECp, NFECp, ..., NFECp, NFECp. Vertical arrows indicate 'Increase in D' and 'Decrease in D'. The 'Increase in D' arrow points to the formula ΔNP + [ (65Lp/8 - ΔNFECp) / NFECp ] \* NFECp. The 'Decrease in D' arrow points to the formula ΔNFECp + [ (65Lp/8 - ΔNFECp) / NFECp ] \* NFECp. The text G.993.2(15)\_F13-1 is at the bottom right. + +**Figure 13-1 – Finding the byte where the change in $D_p$ is activated** + +Figure 13-1 shows the DMT symbol counter and the byte counter at which the interleaver depth change is activated, relative to the Syncflag. For an increase in depth, the change in $D_p$ will always happen at the same time or before the change in $L_p$ , but as close to it as possible (i.e., the change in $D_p$ happens during the DMT symbol with count 64 or sooner). Likewise, for a decrease in depth, the change in $D_p$ will always happen at the same time or after the change in $L_p$ , but as close to it as possible (i.e., the change in $D_p$ happens during the DMT symbol with count 65 or later). + +For OLR Type 4 (SOS), the change in $L_p$ values and $b_i$ values shall take effect starting from the 66th symbol that follows the Syncflag, i.e., the symbol with symbol count 65 in the DMT superframe following the Syncflag, where the first symbol in the DMT superframe is the symbol at symbol count 0. + +For all the used tones in an SOS tone group $k$ , the same $b_i$ reduction $\Delta b(k)$ is applied, except for tones that belong to the ROC. Specifically, the new $b_i' = b_i - \Delta b(k)$ . If the new $b_i'$ value is $< 2$ , it shall be set to 0. Thus, no new 1-bit loading will be created in SOS. If the resulting $b_i'$ contains an odd number of 1-bit constellation points and trellis is enabled, the last (according to reordered tone ordering table) 1-bit constellation should be set to $b_i' = 0$ . + +When the SOS request is executed in multiple steps, the tones shall be updated in groups of size $G_{\text{sos}}$ , where $G_{\text{sos}}$ is the minimum of the values indicated by VTU-R and VTU-O in R-MSG2 and O-MSG1 respectively. The tones shall be updated in the order determined by the reordered tone ordering table. To insure that the bit-loading after each step contains an even number of 1-bit constellation, the tone with the unpaired 1-bit constellation shall be removed from this step and included in the next step. + +The change in bit loading for the first group of tones shall be done at the 66th symbol that follows the Syncflag. The change for subsequent groups shall be done $T_{\text{sos}}$ symbols after the execution of the previous group (on the symbol count $65 + s \times T_{\text{sos}}$ , $s = 1, 2, \dots, N-1$ , sync symbols are not counted) until all tones have been changed. The last group may have less than $G_{\text{sos}}$ tones. The value of $T_{\text{sos}}$ depends on the selected value of $G_{\text{sos}}$ and shall be as presented in Table 13-4. + +NOTE – The number of steps $N$ depends on the total number of tones, $W$ , subject to bit loading change during the SOS. It can be computed as $N = \text{ceiling}(W/G_{\text{sos}})$ . Assuming the maximum number of tones in the transmit direction for the band plans defined in Annexes A, B and C, $N$ does not exceed 12 for $G_{\text{sos}} = 256$ , 6 for $G_{\text{sos}} = 512$ , and 3 for $G_{\text{sos}} = 1\,024$ . + +**Table 13-4 – $G_{\text{sos}}$ and associated values of $T_{\text{sos}}$** + +| $G_{\text{sos}}$ | $T_{\text{sos}}$ (4.3125 kHz) | $T_{\text{sos}}$ (8.625 kHz) | +|------------------|-------------------------------|------------------------------| +| 256 | 48 | 96 | +| 512 | 72 | 144 | +| 1 024 | 96 | 192 | +| All tones | N/A | N/A | + +In the case of multi-step, the value of $D$ (interleaver depth) shall be changed with the last group of tones. The change shall happen at the same symbol or at the first opportunity after the change of bit loading for the last group of tones (during the DMT symbol with count $65 + (N-1) \times T_{\text{sos}}$ or later). + +When the SOS request is executed in a single step, the value of $D$ shall be changed as described in this clause for OLR type 3. + +After it has received an SOS request, the VTU shall respond within 200 ms with either a Syncflag or a reject type 4 invalid parameters response (see Table 11-8). When the execution is done in multiple steps, the total time between reception of the message and full execution of the command shall not exceed 300 ms. In addition, the VTU shall respond within 146.5 ms after it has received an SOS request with either a Syncflag or a reject type 4 invalid parameters response. The response shall be + +sent at the first opportunity after the SOS request is received provided there is enough time to execute the first step of a multi-step activation. + +During the transition of OLR type 4 in single or multiple steps, bit errors may occur. Once the transition is completed, the VTU shall operate at a BER not exceeding the nominal BER, unless the line conditions do not allow it. + +### 13.4 Receiver initiated procedure + +If a VTU receiver initiates a reconfiguration, it computes the necessary change in the related parameters (e.g., bits and gains table) and requests this change in the transmit PMD function of the VTU at the other end of the line. After it receives a positive acknowledgment, as specified in clause 11.2.3.3, the VTU shall change the relevant control parameters of its own receive PMD function and the PMS-TC function at the time specified in clause 13.3. + +A VTU receiver may initiate an OLR Type 1 (Bit Swapping). A bit swap request shall change only the bits and gains table. It shall not modify the *L* value. Bit swapping reconfigurations involve changes of only the PMD sublayer configuration parameters. They do not change the TPS-TC and PMS-TC sublayer configuration parameters. + +The transmit PMD function shall support bit swaps requested by the receive PMD function. + +If OLR type 3 (SRA) is supported (in downstream or upstream direction, respectively), and enabled (through RA-MODE=3), a VTU receiver shall initiate an SRA when the conditions in clause 13.4.1 or clause 13.4.2 are satisfied. + +If OLR type 3 (SRA) is supported (in downstream or upstream direction, respectively), and enabled (through RA-MODE=4), a VTU receiver shall initiate an SRA when the conditions in clause 13.4.1, clause 13.4.2 or clause 13.4.3 are satisfied. A VTU receiver may initiate a SRA when the conditions in clause 13.4.4 are satisfied. + +If OLR type 4 (SOS) is supported (in downstream or upstream direction, respectively), and enabled (through RA-MODE=4), a VTU receiver shall initiate an SOS when the conditions in clause 13.4.3 are satisfied. + +A VTU receiver shall only send OLR request commands that meet all of following constraints: + +- Impulse noise protection $\geq$ Minimum impulse noise protection for all bearer channels; +- Delay $\leq$ Maximum delay for all bearer channels; + +A VTU receiver shall only send SOS requests that meet the following constraints: + +- Net data rate ( $NDR_n$ ) $\geq$ Minimum SOS net data rate ( $MIN-SOS-BR_n$ ) for all bearer channels; + +NOTE – An SOS request could result in a message overhead data rate that is temporarily below the configured minimum message overhead data rate. This will be corrected by a subsequent SRA procedure. See clause 13.4.3.3. + +A VTU receiver shall only send SRA requests that meet the following constraints: + +- Maximum net data rate $\geq$ Net data rate $\geq$ Minimum net data rate for all bearer channels, unless the actual net data rate is below the minimum net data rate as a result of an SOS procedure. In that case, SRA is only allowed to ask for rate increases, but the requested Net data rate is allowed to be below Minimum net data rate; +- Message overhead data rate $\geq$ Minimum message overhead data rate; +- $DV_n \leq DVmax_n$ for all bearer channels. + +#### 13.4.1 Receiver Initiated SRA downshift procedure + +If the noise margin is below the downshift noise margin (*RA-DSNRM*) and stays below that for more than the time specified by the minimum downshift rate adaptation interval (*RA-DTIME*), the VTU + +shall attempt to decrease the net data rate, such that the noise margin is increased to a level higher than or equal to the Downshift Noise Margin + 1 dB (see Figure 13-2). + +![Figure 13-2 – SRA downshift procedure diagram](3c51c7ad97fe744faddbbdc1053bdbeb_img.jpg) + +The diagram illustrates the SRA downshift procedure. It shows a vertical timeline representing the progression of the system. At the top, 'Steady state operation' is indicated. Below this, a dashed horizontal line represents the 'Downshift noise margin + 1 dB' threshold. A solid horizontal line represents the 'Downshift noise margin' threshold. The procedure starts with 'Start rate decrease' at the bottom, indicated by a right-pointing arrow. This is followed by 'Continue rate decrease' (right-pointing arrow) and 'Continue margin decrease' (left-pointing arrow) as the system moves between the two thresholds. The process ends at the 'Downshift noise margin + 1 dB' threshold. The identifier 'G.993.2(15)\_F13-2' is located in the bottom right corner. + +Figure 13-2 – SRA downshift procedure diagram + +**Figure 13-2 – SRA downshift procedure** + +If a $DVmax_p$ parameter specifies a bound on delay variation, it is possible that the rate decrease allowed by this maximum delay variation in a single SRA request is not sufficient to re-establish the margin to downshift noise margin + 1 dB. In this case, a number of consecutive SRA requests shall be executed until the margin is higher than or equal to the downshift noise margin + 1 dB. + +### 13.4.2 Receiver initiated SRA upshift procedure + +If the noise margin is above the upshift noise margin ( $RA-USNRM$ ) and stays above that for more than the time specified by the minimum upshift rate adaptation interval ( $RA-UTIME$ ), the VTU shall attempt to increase the net data rate, such that the noise margin is decreased to a level lower than or equal to the upshift noise margin – 1 dB (see Figure 13-3). + +![Figure 13-3 – SRA upshift procedure diagram](5c62022cb5436e57bc6748b98ce6d2c8_img.jpg) + +The diagram illustrates the SRA upshift procedure. It shows a vertical timeline representing the progression of the system. At the bottom, 'Steady state operation' is indicated. Above this, a dashed horizontal line represents the 'Upshift noise margin – 1 dB' threshold. A solid horizontal line represents the 'Upshift noise margin' threshold. The procedure starts with 'Start rate increase' at the bottom, indicated by a right-pointing arrow. This is followed by 'Continue rate increase' (right-pointing arrow) and 'Continue margin increase' (left-pointing arrow) as the system moves between the two thresholds. The process ends at the 'Upshift noise margin' threshold. The identifier 'G.993.2(15)\_F13-3' is located in the bottom right corner. + +Figure 13-3 – SRA upshift procedure diagram + +**Figure 13-3 – SRA upshift procedure** + +If a $DVmax_p$ parameter specifies a bound on delay variation, it is possible that the rate increase allowed by this maximum delay variation in a single SRA request, is not sufficient to re-establish the margin to upshift noise margin – 1 dB. In this case, a number of consecutive SRA requests shall be executed until the margin is lower than or equal to the upshift noise margin – 1 dB. + +### 13.4.3 Receiver initiated SOS + +#### 13.4.3.1 SOS triggering parameters + +For each direction, three SOS triggering parameters are defined to support the standard SOS triggering criteria defined in clause 13.4.3.2. + +#### 13.4.3.1.1 SOS time Window (SOS-TIME) + +The special value zero indicates that the standard SOS triggering criteria are disabled, i.e., vendor discretionary values may be used instead of the values configured in the MIB for the following parameters: SOS-NTONES, SOS-CRC, and SOS-TIME. + +A non-zero value indicates that the standard SOS triggering criteria are enabled. In this case, SOS-TIME is the duration of the time window used in the standard SOS triggering criteria (see clause 13.4.3.2). This time window shall be applied to sequential time steps (i.e., not a sliding window). + +The SOS-TIME defined for the downstream and upstream are denoted as SOS-TIME-ds and SOS-TIME-us, respectively. + +#### 13.4.3.1.2 Minimum Percentage of Degraded Tones (SOS-NTONES) + +SOS-NTONES is the minimum percentage of loaded tones (i.e., tones with $b_i > 0$ ) that must be persistently degraded throughout the time window SOS-TIME, in order to arm the first subcondition of the standard SOS triggering criteria (see clause 13.4.3.2). + +A degraded tone is a tone that has been identified as needing a reduction in bit loading because, with its current bit loading, it contributes substantially to the increase of the BER above the nominal value. The degraded tones are not necessarily contiguous. + +The SOS-NTONES defined for the downstream and upstream are denoted as SOS-NTONES-ds and SOS-NTONES-us, respectively. + +#### 13.4.3.1.3 Minimum Number of normalized CRC anomalies (SOS-CRC) + +SOS-CRC is the minimum number of normalized CRC anomalies received in SOS-TIME seconds, in order to arm the second subcondition of the standard SOS triggering criteria (see clause 13.4.3.2). + +The "count of normalized CRC anomalies" shall be incremented by the $\Delta$ CRCsecp (the one-second normalized CRC anomaly counter increment, as defined in Table 9-8 of this Recommendation) for each occurrence of a crc-p anomaly. + +The SOS-CRC defined for the downstream and upstream are denoted as SOS-CRC-ds and SOS-CRC-us, respectively. + +#### 13.4.3.2 Standard SOS triggering criteria + +If the following conditions hold: + +- the standard SOS triggering criteria are enabled (through SOS-TIME $\neq 0$ ); +- the percentage of tones in the MEDLEY SET that are persistently degraded throughout the time window SOS-TIME exceeds SOS-NTONES; and +- the count of normalized CRC anomalies throughout the same time window SOS-TIME exceeds SOS-CRC. + +then the VTU: + +- shall send either an SOS request or an SRA request if the number of degraded tones is $\leq 128$ and the message length of the SRA request has a duration less than 100 ms; or +- shall send an SOS request if the number of degraded tones $> 128$ or if the message length of the SRA request has a duration more than 100 ms. + +These SRA requests are not required to respect either RA-TIME or RA-SNRM. + +The time between the moment that the SOS trigger conditions have become valid, and the SOS request or SRA request sent by the VTU appears at the U-interface, shall be less than 128 ms if there is no other outstanding OLR request. + +If the standard SOS triggering criteria are disabled (through $SOS-TIME = 0$ ), the VTU may send SOS requests or SRA requests based on vendor-discretionary SOS triggering criteria. After each successful SOS, or SRA based on SOS triggering criteria, the count of normalized CRC anomalies shall be reset and a new time window shall be started. + +### 13.4.3.3 Generic requirements for receiver initiated SOS + +The VTU shall not send an SOS request if SOS is disabled ( $RA-MODE \neq 4$ ). + +In the case the SOS results in a $PER_p$ value outside the bounds given in Table 9-8, the VTU that initiated the SOS request shall send a subsequent SRA request within 1 second to bring the $PER_p$ back within these bounds. + +In the case the SOS results in an $msg_p$ value outside the bounds given in Table 9-8, the VTU that initiated the SOS request shall send a subsequent SRA request within 1 second to bring the $msg_p$ back within these bounds. + +### 13.4.4 Receiver Initiated SRA following an SOS procedure + +A VTU shall send one or more SRA requests following an SOS procedure to remediate the situation in which the current rate is less than Minimum Net Data Rate, or the actual noise margin is greater than the target noise margin. As long as the current bit rate is less than Minimum Net Data Rate, or the actual noise margin is greater than the target noise margin, these SRA requests are not required to respect either $RA-UTIME$ or $RA-USNRM$ . + +NOTE – Although these SRA requests can be issued at the discretion of the VTU, the Note in clause 13.1 defines a goal for the overall duration of the SOS procedure. + +## 14 Electrical requirements + +### 14.1 Termination impedance model + +The termination impedance model is for further study. + +NOTE – The reference impedance model is intended to be used for splitter testing only, and is not intended to imply requirements on the values of the input impedance to be implemented in the transceiver. + +### 14.2 Service splitters + +For further study. + +### 14.3 Input capacitance + +Input capacitance requirements are shown in Table 14-1. + +**Table 14-1 – Input capacitance requirements** + +| Underlying service | | | Min capacitance (nF) | Max capacitance (nF) | +|---------------------------|----------------|-------------|-----------------------------|-----------------------------| +| POTS | Integrated HPF | With US0 | 20 | 34 | +| | | Without US0 | For further study | 34 | +| | External HPF | With US0 | 30 | 78 | +| | | Without US0 | For further study | 78 | +| ISDN | Integrated HPF | With US0 | 6 | 11 | +| | | Without US0 | For further study | 11 | +| | External HPF | With US0 | 10.8 | 59 | +| | | Without US0 | For further study | 59 | +| No underlying service | N/A | N/A | No requirement | No requirement | + +NOTE – Capacitance shall be measured at a single frequency $\leq 4$ kHz for over POTS and $\leq 30$ kHz for over ISDN. + +## Annex A + +### Region A (North America) + +(This annex forms an integral part of this Recommendation.) + +#### A.1 Band plan + +The band plan for North America is shown in Figures A.1 and A.1.1. The US0 band, if present, has a lower frequency, $f_{0L}$ , which can vary from 4 kHz (without POTS) to 25 kHz (with POTS), and an upper frequency, $f_{0H}$ , which can vary from 138 to 276 kHz. + +![Figure A.1: Band plan 998-30 for North America. A frequency spectrum diagram showing segments US0, DS1, US1, DS2, US2, DS3, and US3. Breakpoints are marked at f_0L, f_0H, f_1, 3.75, 5.2, 8.5, 12, 23, and 30 MHz. Reference G.993.2(15)_FA-1.](e4a32ec6d1b56eec38fd6f6313f83b06_img.jpg) + +| | | | | | | | | | +|----------|----------|-------|------|-----|-----|-----|-----|----| +| US0 | (shaded) | DS1 | US1 | DS2 | US2 | DS3 | US3 | | +| $f_{0L}$ | $f_{0H}$ | $f_1$ | 3.75 | 5.2 | 8.5 | 12 | 23 | 30 | + +G.993.2(15)\_FA-1 + +Figure A.1: Band plan 998-30 for North America. A frequency spectrum diagram showing segments US0, DS1, US1, DS2, US2, DS3, and US3. Breakpoints are marked at f\_0L, f\_0H, f\_1, 3.75, 5.2, 8.5, 12, 23, and 30 MHz. Reference G.993.2(15)\_FA-1. + +Figure A.1 – Band plan 998-30 for North America + +![Figure A.1.1: Band plan 998-35b for North America. A frequency spectrum diagram showing segments US0, DS1, US1, DS2, US2, and DS3. Breakpoints are marked at f_0L, f_0H, f_1, 3.75, 5.2, 8.5, 12, and 35 MHz. Reference G.993.2(15)-Amd.4(18)_FA.1.1.](3ea2a1f3b801526c45a1a02c3f983822_img.jpg) + +| | | | | | | | | +|----------|----------|-------|------|-----|-----|-----|----| +| US0 | (shaded) | DS1 | US1 | DS2 | US2 | DS3 | | +| $f_{0L}$ | $f_{0H}$ | $f_1$ | 3.75 | 5.2 | 8.5 | 12 | 35 | + +G.993.2(15)-Amd.4(18)\_FA.1.1 + +Figure A.1.1: Band plan 998-35b for North America. A frequency spectrum diagram showing segments US0, DS1, US1, DS2, US2, and DS3. Breakpoints are marked at f\_0L, f\_0H, f\_1, 3.75, 5.2, 8.5, 12, and 35 MHz. Reference G.993.2(15)-Amd.4(18)\_FA.1.1. + +Figure A.1.1 – Band plan 998-35b for North America + +NOTE – Deployments for these two band plans are not spectrally compatible over 23 MHz. + +#### A.2 Limit PSD masks + +The breakpoint frequencies and PSD values in Tables A.1 through A.8 are exact. The indicated slopes shown in corresponding Figures A.2 through A.6 are approximate. + +NOTE 1 – The out-of-band specification above 1.1 MHz is governed by the stopband specification in Table 7-2. + +NOTE 2 – It is expected that methods to verify compliance to the Limit PSD mask will be defined by the regional bodies. + +##### A.2.1 VTU-R Limit PSD masks + +The Limit PSD mask between the breakpoints is determined using the following interpolation rules: + +- For frequencies less than (3 750 – 175) kHz, the breakpoints in Tables A.1 through A.8 shall be connected linearly on a plot with the abscissa $\log_{10}(f)$ and the ordinate the Limit PSD mask in dBm/Hz; +- For frequencies above (3 750 – 175) kHz, the breakpoints in Tables A.1 through A.8 shall be connected linearly on a plot with the abscissa $f$ and the ordinate the Limit PSD mask in dBm/Hz. + +### A.2.1.1 VTU-R operation over POTS + +![Figure A.2: VTU-R US0 Limit PSD mask for operation over POTS. The graph shows PSD in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, f_0H, f_int, 686, and (3750-175). The y-axis has markers at -97.5 peak +15 dBm (0-4 kHz), -92.5 dBm/Hz, and PSD1. The PSD mask starts at -97.5 dBm/Hz at 0 kHz, rises to -92.5 dBm/Hz at 4 kHz with a slope of (PSD1+92.5)/Log2(25.875/4) dB/octave, reaches PSD1 at 25.875 kHz, remains constant until f_0H, then drops with a slope of -72 dB/octave to -15 dB/dec at f_int, then drops with a slope of -15 dB/dec to -100 dBm/Hz at 686 kHz, and finally rises with a slope of -100 dBm/Hz to the end of the band at (3750-175) kHz. A label PSD_int dBm/Hz is also present.](0a86aca34c8cee8cba99b633fb7a9726_img.jpg) + +Figure A.2: VTU-R US0 Limit PSD mask for operation over POTS. The graph shows PSD in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, f\_0H, f\_int, 686, and (3750-175). The y-axis has markers at -97.5 peak +15 dBm (0-4 kHz), -92.5 dBm/Hz, and PSD1. The PSD mask starts at -97.5 dBm/Hz at 0 kHz, rises to -92.5 dBm/Hz at 4 kHz with a slope of (PSD1+92.5)/Log2(25.875/4) dB/octave, reaches PSD1 at 25.875 kHz, remains constant until f\_0H, then drops with a slope of -72 dB/octave to -15 dB/dec at f\_int, then drops with a slope of -15 dB/dec to -100 dBm/Hz at 686 kHz, and finally rises with a slope of -100 dBm/Hz to the end of the band at (3750-175) kHz. A label PSD\_int dBm/Hz is also present. + +Figure A.2 – VTU-R US0 Limit PSD mask for operation over POTS + +![Figure A.3: VTU-R EU-128 Limit PSD mask for operation over POTS. The graph shows PSD in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, 138, f_0H = 552, 989, and (3750-175). The y-axis has markers at -97.5 peak +15 dBm (0-4 kHz), -92.5 dBm/Hz, -34.5 dBm/Hz, and -40.6 dBm/Hz. The PSD mask starts at -97.5 dBm/Hz at 0 kHz, rises to -92.5 dBm/Hz at 4 kHz with a slope of 58/Log2(25.875/4) dB/octave, reaches -34.5 dBm/Hz at 25.875 kHz, remains constant until 138 kHz, then drops with a slope of -40.6 dBm/Hz to -72 dB/octave at f_0H = 552 kHz, then drops with a slope of -72 dB/octave to -100 dBm/Hz at 989 kHz, and finally rises with a slope of -100 dBm/Hz to the end of the band at (3750-175) kHz.](8ce9decfe331b11186a76f813e5dd62c_img.jpg) + +Figure A.3: VTU-R EU-128 Limit PSD mask for operation over POTS. The graph shows PSD in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, 138, f\_0H = 552, 989, and (3750-175). The y-axis has markers at -97.5 peak +15 dBm (0-4 kHz), -92.5 dBm/Hz, -34.5 dBm/Hz, and -40.6 dBm/Hz. The PSD mask starts at -97.5 dBm/Hz at 0 kHz, rises to -92.5 dBm/Hz at 4 kHz with a slope of 58/Log2(25.875/4) dB/octave, reaches -34.5 dBm/Hz at 25.875 kHz, remains constant until 138 kHz, then drops with a slope of -40.6 dBm/Hz to -72 dB/octave at f\_0H = 552 kHz, then drops with a slope of -72 dB/octave to -100 dBm/Hz at 989 kHz, and finally rises with a slope of -100 dBm/Hz to the end of the band at (3750-175) kHz. + +Figure A.3 – VTU-R EU-128 Limit PSD mask for operation over POTS + +Table A.1 – VTU-R Limit PSD mask for operation over POTS as a function of profile + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | Limit PSD mask level (dBm/Hz) for profile 35b | +|-----------------|-----------------------------------------------------------|----------------------------------------------------------|-----------------------------------------------|-----------------------------------------------| +| 0 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -92.5 | -92.5 | -92.5 | -92.5 | +| 25.875 | PSD1 (see Table A.2) | PSD1 | PSD1 (see Table A.2) | PSD1 (see Table A.2) | +| $f_{0H}$ | PSD1 (see Table A.2) | PSD1 | PSD1 (see Table A.2) | PSD1 (see Table A.2) | + +**Table A.1 – VTU-R Limit PSD mask for operation over POTS as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | Limit PSD mask level (dBm/Hz) for profile 35b | +|-----------------|-----------------------------------------------------------|----------------------------------------------------------|-----------------------------------------------|-----------------------------------------------| +| $f\_int$ | $PSD\_int$ (see Table A.2) | $PSD\_int$ | $PSD\_int$ (see Table A.2) | $PSD\_int$ (see Table A.2) | +| 686 | -100 | -100 | -100 | -100 | +| 1 104 | -100 | -100 | -100 | -100 | +| 3 750 – 175 | -100 | -100 | -100 | -100 | +| 3 750 | -80 | -80 | -80 | -80 | +| 3 750 | -53 + 3.5 | -53 + 3.5 | -53 + 3.5 | -53 + 3.5 | +| 5 200 | -53 + 3.5 | -53 + 3.5 | -53 + 3.5 | -53 + 3.5 | +| 5 200 | -80 | -80 | -80 | -80 | +| 5 200 + 175 | -100 | -100 | -100 | -100 | +| 8 500 – 175 | -100 | -100 | -100 | -100 | +| 8 500 | -100 | -80 | -80 | -80 | +| 8 500 | -100 | -54 + 3.5 | -54 + 3.5 | -54 + 3.5 | +| 12 000 | -100 | -54 + 3.5 | -54 + 3.5 | -54 + 3.5 | +| 12 000 | -100 | -80 | -80 | -80 | +| 12 000 + 175 | -100 | -100 | -100 | -100 | +| 23 000 – 175 | -100 | -100 | -100 | -100 | +| 23 000 | -100 | -100 | -80 | -100 | +| 23 000 | -100 | -100 | -60 + 3.5 | -100 | +| 30 000 | -100 | -100 | -60 + 3.5 | -100 | +| 30 000 | -110 | -110 | -80 | -110 | +| 30 175 | -110 | -110 | -110 | -110 | +| $\geq 30 175$ | -110 | -110 | -110 | -110 | + +**Table A.2 – $PSD1$ , $PSD\_int$ and the frequencies $f_{OH}$ and $f\_int$** + +| Upstream mask-number | Designator | $PSD1$ (dBm/Hz) | Frequency $f_{OH}$ (kHz) | Intercept frequency $f\_int$ (kHz) | Intercept PSD level $PSD\_int$ (dBm/Hz) | +|----------------------|------------|-----------------|--------------------------|------------------------------------|-----------------------------------------| +| 1 | EU-32 | -34.5 | 138.00 | 242.92 | -93.2 | +| 2 | EU-36 | -35.0 | 155.25 | 274.00 | -94.0 | +| 3 | EU-40 | -35.5 | 172.50 | 305.16 | -94.7 | +| 4 | EU-44 | -35.9 | 189.75 | 336.40 | -95.4 | +| 5 | EU-48 | -36.3 | 207.00 | 367.69 | -95.9 | +| 6 | EU-52 | -36.6 | 224.25 | 399.04 | -96.5 | +| 7 | EU-56 | -36.9 | 241.50 | 430.45 | -97.0 | + +**Table A.2 – *PSD1*, *PSD\_int* and the frequencies *fOH* and *fint*** + +| Upstream mask-number | Designator | PSD1 (dBm/Hz) | Frequency fOH (kHz) | Intercept frequency fint (kHz) | Intercept PSD level PSD_int (dBm/Hz) | +|-------------------------------------------------------------------------|------------|----------------------|---------------------------------------|--------------------------------------------------|---------------------------------------------| +| 8 | EU-60 | -37.2 | 258.75 | 461.90 | -97.4 | +| 9 | EU-64 | -37.5 | 276.00 | 493.41 | -97.9 | +| NOTE – EU-32 through EU-64 shall not be used in conjunction with D-128. | | | | | | + +**Table A.3 – VTU-R EU-128 Limit PSD mask for operation over POTS as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | Limit PSD mask level (dBm/Hz) for profile 35b | +|-----------------------------|-----------------------------------------------------------|----------------------------------------------------------|----------------------------------------------------------|----------------------------------------------------------| +| 0 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -92.5 | -92.5 | -92.5 | -92.5 | +| 25.875 | -34.5 | -34.5 | -34.5 | -34.5 | +| 138 | -34.5 | -34.5 | -34.5 | -34.5 | +| fOH = 552 | -34.5
$- 10 \times \log_{10}(f_{OH} - 3) / (138 - 3)$ | -34.5
$- 10 \times \log_{10}(f_{OH} - 3) / (138 - 3)$ | -34.5
$- 10 \times \log_{10}(f_{OH} - 3) / (138 - 3)$ | -34.5
$- 10 \times \log_{10}(f_{OH} - 3) / (138 - 3)$ | +| 989 | -100 | -100 | -100 | -100 | +| 1 104 | -100 | -100 | -100 | -100 | +| 3 750 – 175 | -100 | -100 | -100 | -100 | +| 3 750 | -80 | -80 | -80 | -80 | +| 3 750 | $-53 + 3.5$ | $-53 + 3.5$ | $-53 + 3.5$ | $-53 + 3.5$ | +| 5 200 | $-53 + 3.5$ | $-53 + 3.5$ | $-53 + 3.5$ | $-53 + 3.5$ | +| 5 200 | -80 | -80 | -80 | -80 | +| 5 200 + 175 | -100 | -100 | -100 | -100 | +| 8 500 – 175 | -100 | -100 | -100 | -100 | +| 8 500 | -100 | -80 | -80 | -80 | +| 8 500 | -100 | $-54 + 3.5$ | $-54 + 3.5$ | $-54 + 3.5$ | +| 12 000 | -100 | $-54 + 3.5$ | $-54 + 3.5$ | $-54 + 3.5$ | +| 12 000 | -100 | -80 | -80 | -80 | +| 12 000 + 175 | -100 | -100 | -100 | -100 | +| 23 000 – 175 | -100 | -100 | -100 | -100 | +| 23 000 | -100 | -100 | -80 | -100 | +| 23 000 | -100 | -100 | $-60 + 3.5$ | -100 | +| 30 000 | -100 | -100 | $-60 + 3.5$ | -100 | + +**Table A.3 – VTU-R EU-128 Limit PSD mask for operation over POTS as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | Limit PSD mask level (dBm/Hz) for profile 35b | +|-----------------|-----------------------------------------------------------|----------------------------------------------------------|-----------------------------------------------|-----------------------------------------------| +| 30 000 | -110 | -110 | -80 | -110 | +| 30 175 | -110 | -110 | -110 | -110 | +| $\geq 30\ 175$ | -110 | -110 | -110 | -110 | + +**A.2.1.2 VTU-R All-digital mode operation** + +![Graph of PSD in dBm/Hz vs Frequency in kHz for VTU-R US0. The graph shows a piecewise linear mask with segments labeled PSD1 and PSDint. Key points include a peak at 46.5 dBm/Hz, a flat section at PSD1, a steep drop at -72 dB/octave, a shallower drop at -15 dB/dec, and a final flat section at -100 dBm/Hz. Frequency markers include 0, 1.5, 3, f_oh, f_int, 686, and (3750-175) kHz.](e77f9abb052e12e90a8480b9e1e4b571_img.jpg) + +Figure A.4 shows the VTU-R US0 Limit PSD mask for all-digital mode operation. The y-axis represents PSD in dBm/Hz, and the x-axis represents Frequency in kHz. The mask is defined by several segments: + + +- From 0 to 1.5 kHz: A horizontal segment at $-46.5\ \text{dBm/Hz}$ (peak). +- From 1.5 to 3 kHz: An upward sloping segment with a slope of $(PSD1 + 46.5) / \log_2(3/1.5)\ \text{dB/octave}$ . +- From 3 to $f_{oh}$ : A horizontal segment at level $PSD1$ . +- From $f_{oh}$ to $f_{int}$ : A steep downward sloping segment with a slope of $-72\ \text{dB/octave}$ . +- From $f_{int}$ to 686 kHz: A downward sloping segment with a slope of $-15\ \text{dB/dec}$ . +- From 686 kHz to $(3750-175)$ kHz: A horizontal segment at level $PSDint$ . +- Below 686 kHz and above $(3750-175)$ kHz: A floor level of $-100\ \text{dBm/Hz}$ . + +Graph of PSD in dBm/Hz vs Frequency in kHz for VTU-R US0. The graph shows a piecewise linear mask with segments labeled PSD1 and PSDint. Key points include a peak at 46.5 dBm/Hz, a flat section at PSD1, a steep drop at -72 dB/octave, a shallower drop at -15 dB/dec, and a final flat section at -100 dBm/Hz. Frequency markers include 0, 1.5, 3, f\_oh, f\_int, 686, and (3750-175) kHz. + +**Figure A.4 – VTU-R US0 Limit PSD mask for all-digital mode operation** + +![Graph of PSD in dBm/Hz vs Frequency in kHz for VTU-R ADLU-128. The graph shows a piecewise linear mask with segments labeled PSD1 and PSDint. Key points include a peak at 46.5 dBm/Hz, a flat section at -34.5 dBm/Hz, a drop at -40.6 dBm/Hz, a steep drop at -72 dB/octave, and a final flat section at -100 dBm/Hz. Frequency markers include 0, 1.5, 3, 138, f_oh = 552, 989, and (3750-175) kHz.](17f63ca1463dd3a235a7bea317eceba2_img.jpg) + +Figure A.5 shows the VTU-R ADLU-128 limit PSD mask for all-digital mode operation. The y-axis represents PSD in dBm/Hz, and the x-axis represents Frequency in kHz. The mask is defined by several segments: + + +- From 0 to 1.5 kHz: A horizontal segment at $-46.5\ \text{dBm/Hz}$ (peak). +- From 1.5 to 3 kHz: An upward sloping segment with a slope of $12 / \log_2(3/1.5)\ \text{dB/octave}$ . +- From 3 to 138 kHz: A horizontal segment at level $-34.5\ \text{dBm/Hz}$ . +- From 138 to $f_{oh} = 552$ kHz: A downward sloping segment with a slope of $-40.6\ \text{dBm/Hz}$ . +- From $f_{oh} = 552$ to 989 kHz: A steep downward sloping segment with a slope of $-72\ \text{dB/octave}$ . +- From 989 kHz to $(3750-175)$ kHz: A horizontal segment at level $PSDint$ . +- Below 989 kHz and above $(3750-175)$ kHz: A floor level of $-100\ \text{dBm/Hz}$ . + +Graph of PSD in dBm/Hz vs Frequency in kHz for VTU-R ADLU-128. The graph shows a piecewise linear mask with segments labeled PSD1 and PSDint. Key points include a peak at 46.5 dBm/Hz, a flat section at -34.5 dBm/Hz, a drop at -40.6 dBm/Hz, a steep drop at -72 dB/octave, and a final flat section at -100 dBm/Hz. Frequency markers include 0, 1.5, 3, 138, f\_oh = 552, 989, and (3750-175) kHz. + +**Figure A.5 – VTU-R ADLU-128 limit PSD mask for all-digital mode operation** + +**Table A.4 – VTU-R limit PSD mask for all-digital mode operation as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | +|-----------------|-----------------------------------------------------------|----------------------------------------------------------|-----------------------------------------------| +| 0 | -46.5 | -46.5 | -46.5 | +| 1.5 | -46.5 | -46.5 | -46.5 | +| 3 | PSDI (see Table A.5) | PSDI | PSDI (see Table A.5) | +| $f_{0H}$ | PSDI (see Table A.5) | PSDI | PSDI (see Table A.5) | +| $f_{int}$ | PSDint (see Table A.5) | PSDint | PSDint (see Table A.5) | +| 686 | -100 | -100 | -100 | +| 1 104 | -100 | -100 | -100 | +| 3 750 – 175 | -100 | -100 | -100 | +| 3 750 | -80 | -80 | -80 | +| 3 750 | -53 + 3.5 | -53 + 3.5 | -53 + 3.5 | +| 5 200 | -53 + 3.5 | -53 + 3.5 | -53 + 3.5 | +| 5 200 | -80 | -80 | -80 | +| 5 200 + 175 | -100 | -100 | -100 | +| 8 500 – 175 | -100 | -100 | -100 | +| 8 500 | -100 | -80 | -80 | +| 8 500 | -100 | -54 + 3.5 | -54 + 3.5 | +| 12 000 | -100 | -54 + 3.5 | -54 + 3.5 | +| 12 000 | -100 | -80 | -80 | +| 12 000 + 175 | -100 | -100 | -100 | +| 23 000 – 175 | -100 | -100 | -100 | +| 23 000 | -100 | -100 | -80 | +| 23 000 | -100 | -100 | -60 + 3.5 | +| 30 000 | -100 | -100 | -60 + 3.5 | +| 30 000 | -110 | -110 | -80 | +| 30 175 | -110 | -110 | -110 | +| $\geq 30\ 175$ | -110 | -110 | -110 | + +**Table A.5 – *PSDI*, *PSDint* and the frequencies $f_{0H}$ and $f_{int}$** + +| Upstream mask-number | Designator | PSDI (dBm/Hz) | Frequency $f_{0H}$ (kHz) | Intercept frequency $f_{int}$ (kHz) | Intercept PSD level PSDint (dBm/Hz) | +|----------------------|------------|----------------------|--------------------------|-------------------------------------|--------------------------------------------| +| 1 | ADLU-32 | -34.5 | 138.00 | 242.92 | -93.2 | +| 2 | ADLU-36 | -35.0 | 155.25 | 274.00 | -94.0 | +| 3 | ADLU-40 | -35.5 | 172.50 | 305.16 | -94.7 | +| 4 | ADLU-44 | -35.9 | 189.75 | 336.40 | -95.4 | + +**Table A.5 – *PSD1*, *PSDint* and the frequencies $f_{0H}$ and $f_{int}$** + +| Upstream mask-number | Designator | PSD1 (dBm/Hz) | Frequency $f_{0H}$ (kHz) | Intercept frequency $f_{int}$ (kHz) | Intercept PSD level PSDint (dBm/Hz) | +|----------------------|------------|----------------------|--------------------------|-------------------------------------|--------------------------------------------| +| 5 | ADLU-48 | –36.3 | 207.00 | 367.69 | –95.9 | +| 6 | ADLU-52 | –36.6 | 224.25 | 399.04 | –96.5 | +| 7 | ADLU-56 | –36.9 | 241.50 | 430.45 | –97.0 | +| 8 | ADLU-60 | –37.2 | 258.75 | 461.90 | –97.4 | +| 9 | ADLU-64 | –37.5 | 276.00 | 493.41 | –97.9 | + +NOTE – ADLU-32 through ADLU-64 shall not be used in conjunction with D-128. + +**Table A.6 – VTU-R ADLU-128 Limit PSD mask for all-digital mode operation as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | +|-----------------|-----------------------------------------------------------|----------------------------------------------------------|-------------------------------------------------------| +| 0 | –46.5 | –46.5 | –46.5 | +| 1.5 | –46.5 | –46.5 | –46.5 | +| 3 | –34.5 | –34.5 | –34.5 | +| 138 | –34.5 | –34.5 | –34.5 | +| $f_{0H} = 552$ | $-34.5 - 10 \times \log_{10}(f_{0H} - 3) / (138 - 3)$ | $-34.5 - 10 \times \log_{10}(f_{0H} - 3) / (138 - 3)$ | $-34.5 - 10 \times \log_{10}(f_{0H} - 3) / (138 - 3)$ | +| 989 | –100 | –100 | –100 | +| 1 104 | –100 | –100 | –100 | +| 3 750 – 175 | –100 | –100 | –100 | +| 3 750 | –80 | –80 | –80 | +| 3 750 | –53 + 3.5 | –53 + 3.5 | –53 + 3.5 | +| 5 200 | –53 + 3.5 | –53 + 3.5 | –53 + 3.5 | +| 5 200 | –80 | –80 | –80 | +| 5 200 + 175 | –100 | –100 | –100 | +| 8 500 – 175 | –100 | –100 | –100 | +| 8 500 | –100 | –80 | –80 | +| 8 500 | –100 | –54 + 3.5 | –54 + 3.5 | +| 12 000 | –100 | –54 + 3.5 | –54 + 3.5 | +| 12 000 | –100 | –80 | –80 | +| 12 000 + 175 | –100 | –100 | –100 | +| 23 000 – 175 | –100 | –100 | –100 | +| 23 000 | –100 | –100 | –80 | +| 23 000 | –100 | –100 | –60 + 3.5 | +| 30 000 | –100 | –100 | –60 + 3.5 | + +**Table A.6 – VTU-R ADLU-128 Limit PSD mask for all-digital mode operation as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d | Limit PSD mask level (dBm/Hz) for profiles 12a, 12b, 17a | Limit PSD mask level (dBm/Hz) for profile 30a | +|-----------------|-----------------------------------------------------------|----------------------------------------------------------|-----------------------------------------------| +| 30 000 | -110 | -110 | -80 | +| 30 175 | -110 | -110 | -110 | +| $\geq 30\ 175$ | -110 | -110 | -110 | + +NOTE – The actual transmit PSD shape is further constrained by the total power limit of 14.5 dBm as well as additional spectral compatibility rules imposed by regional authorities. + +### A.2.2 VTU-O Limit PSD masks + +The Limit PSD mask between the breakpoints is determined using the following interpolation rules: + +- For frequencies less than $f_i$ , the breakpoints in Tables A.1 through A.8 shall be connected linearly on a plot with the abscissa $\log_{10}(f)$ and the ordinate the Limit PSD mask in dBm/Hz. +- For frequencies above $f_i$ , the breakpoints in Tables A.1 through A.8 shall be connected linearly a plot with the abscissa $f$ and the ordinate the Limit PSD mask in dBm/Hz. + +![Figure A.6 – VTU-O DS1 limit PSD mask. This is a line graph showing the Power Spectral Density (PSD) in dBm/Hz on the y-axis against Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, f_a, f_int, f_i, 1104, 1622, 3750, and 3750+175. The y-axis has markers at -97.5 peak +15 dB m (0-4 kHz), -44.2 dBm/Hz, -36.5 dBm/Hz peak PSD, -46.5 dBm/Hz, -50 dBm/Hz, -80 dBm/Hz, and -100 dBm/Hz. The graph shows a piecewise linear mask with segments labeled PSDa and PSDint. Slopes are indicated as -0.019 dB/kHz and -0.00164 dB/kHz.](5d4267cc07adeb0c8c5234bf5d605522_img.jpg) + +G.993.2(15)\_FA.6 + +Figure A.6 – VTU-O DS1 limit PSD mask. This is a line graph showing the Power Spectral Density (PSD) in dBm/Hz on the y-axis against Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, f\_a, f\_int, f\_i, 1104, 1622, 3750, and 3750+175. The y-axis has markers at -97.5 peak +15 dB m (0-4 kHz), -44.2 dBm/Hz, -36.5 dBm/Hz peak PSD, -46.5 dBm/Hz, -50 dBm/Hz, -80 dBm/Hz, and -100 dBm/Hz. The graph shows a piecewise linear mask with segments labeled PSDa and PSDint. Slopes are indicated as -0.019 dB/kHz and -0.00164 dB/kHz. + +**Figure A.6 – VTU-O DS1 limit PSD mask** + +**Table A.7 – VTU-O Limit PSD mask as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d, 12a and 12b | Limit PSD mask level (dBm/Hz) for profile 17a | Limit PSD mask level (dBm/Hz) for profile 30a | Limit PSD Mask level (dBm/Hz) for profile 35b | +|-----------------|------------------------------------------------------------------------|-----------------------------------------------|-----------------------------------------------|-----------------------------------------------| +| 0 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | PSDa (see Table A.8) | PSDa (see Table A.8) | PSDa (see Table A.8) | PSDa (see Table A.8) | + +**Table A.7 – VTU-O Limit PSD mask as a function of profile** + +| Frequency (kHz) | Limit PSD mask level (dBm/Hz) for profiles 8a, 8b, 8c, 8d, 12a and 12b | Limit PSD mask level (dBm/Hz) for profile 17a | Limit PSD mask level (dBm/Hz) for profile 30a | Limit PSD Mask level (dBm/Hz) for profile 35b | +|-----------------|------------------------------------------------------------------------|-----------------------------------------------|-----------------------------------------------|-----------------------------------------------| +| $f_a$ | PSDa (see Table A.8) | PSDa (see Table A.8) | PSDa (see Table A.8) | PSDa (see Table A.8) | +| $f_{int}$ | PSDint (see Table A.8) | PSDint (see Table A.8) | PSDint (see Table A.8) | PSDint (see Table A.8) | +| $f_1$ | -44.2 | -44.2 | -44.2 | -44.2 | +| $f_1$ | -36.5 | -36.5 | -36.5 | -36.5 | +| 1 104 | -36.5 | -36.5 | -36.5 | -36.5 | +| 1 622 | -50 + 3.5 | -50 + 3.5 | -50 + 3.5 | -50 + 3.5 | +| 3 750 | -53.5 + 3.5 | -53.5 + 3.5 | -53.5 + 3.5 | -53.5 + 3.5 | +| 3 750 | -80 | -80 | -80 | -80 | +| 3 750 + 175 | -100 | -100 | -100 | -100 | +| 5 200 - 175 | -100 | -100 | -100 | -100 | +| 5 200 | -80 | -80 | -80 | -80 | +| 5 200 | -55 + 3.5 | -55 + 3.5 | -55 + 3.5 | -55 + 3.5 | +| 8 500 | -55 + 3.5 | -55 + 3.5 | -55 + 3.5 | -55 + 3.5 | +| 8 500 | -80 | -80 | -80 | -80 | +| 8 500 + 175 | -100 | -100 | -100 | -100 | +| 12 000 - 175 | -100 | -100 | -100 | -100 | +| 12 000 | -100 | -80 | -80 | -80 | +| 12 000 | -100 | -60 + 3.5 | -60 + 3.5 | -60 + 3.5 | +| 17 664 | -100 | -60 + 3.5 | -60 + 3.5 | -60 + 3.5 | +| 21 000 | -100 | -80 | -60 + 3.5 | -60 + 3.5 | +| 21 450 | -100 | -100 | -60 + 3.5 | -60 + 3.5 | +| 23 000 | -100 | -100 | -60 + 3.5 | -60 + 3.5 | +| 23 000 | -100 | -100 | -80 | -60 + 3.5 | +| 23 000 + 175 | -100 | -100 | -100 | -60 + 3.5 | +| 30 000 | -100 | -100 | -100 | -60 + 3.5 | +| 30 000 | -110 | -110 | -110 | -73 | +| 35 328 | -110 | -110 | -110 | -73.4 | +| 37 000 | -110 | -110 | -110 | -83 | +| 40 656 | -110 | -110 | -110 | -110 | +| > 40 656 | -110 | -110 | -110 | -110 | + +**Table A.8 – *PSD\_int* and *PSDa* and the frequencies *fi*, *f\_int*, and *fa*** + +| Designator | fi
(kHz) | fint
(kHz) | PSDint
(dBm/Hz) | fa
(kHz) | PSDa
(dBm/Hz) | +|-------------------------------------------------------------------------|---------------------------------------|-----------------------------------------|----------------------------------------------|---------------------------------------|--------------------------------------------| +| D-32 | 138.00 | 80 | -72.5 | 4 | -92.5 | +| D-48 | 207.00 | 155 | -62 | 53 | -90 | +| D-64 | 276.00 | 227.1 | -62 | 101.2 | -90 | +| D-128 (Note) | 552.00 | 440 | -68 | 240 | -90 | +| NOTE – D-128 shall only be used in conjunction with EU-128 or ADLU-128. | | | | | | + +### **A.3 UPBO reference PSDs** + +ATIS Committee NIPP has published a technical report [b-ATIS-0600023] that provides guidance on the configuration of the UPBO parameters 'a' and 'b' for the North American environment. + +## Annex B + +### Region B (Europe) + +(This annex forms an integral part of this Recommendation.) + +#### B.1 Band plans + +This annex defines the various band plans required for European deployment of VDSL2 systems operating at a maximum frequency of 12, 17, 30 or 35 MHz. These are based on [ITU-T G.993.1] band plans A and B (also referred to as plan 998 and plan 997, respectively). The various band plans are defined in Table B.1 below and can be summarized as follows: + +| | | +|----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Plan 997 | The original plan 997 ( $f_{max} = 12$ MHz). | +| Plan 997E17 | Plan 997 directly extended to $f_{max} = 17.664$ MHz. | +| Plan 997E30 | Plan 997 directly extended to $f_{max} = 30$ MHz.
NOTE – Plan 997E17 and plan 997 are truncated versions of plan 997E30. | +| Plan 998 | The original plan 998 ( $f_{max} = 12$ MHz). | +| Plan 998E17 | Plan 998 directly extended to $f_{max} = 17.664$ MHz. | +| Plan 998E30 | Plan 998 directly extended to $f_{max} = 30$ MHz.
NOTE – Plan 998E17 and plan 998 are truncated versions of plan 998E30. | +| Plan 998E35 | Plan 998 directly extended to $f_{max} = 35.328$ MHz (frequencies above 14 MHz are for downstream transmission only).
NOTE – Plan 998E17 and plan 998 are truncated versions of plan 998E30 and plan 998E35. | +| Plan 998ADE17 | Plan 998 extended to $f_{max} = 17.664$ MHz (downstream transmission only above 12 MHz) | +| Plan 998ADE30 | Plan 998 extended to $f_{max} = 30$ MHz. | +| Plan 998ADE35 | Plan 998 extended to $f_{max} = 35.328$ MHz (frequencies above 12 MHz are for downstream transmission only).
NOTE – Plan 998ADE17 and plan 998 are truncated versions of plan 998ADE30 and plan 998ADE35. | + +Different variants are defined for band plans 997, 998, 998E17, 998E30, 998E35, 998ADE17, 998ADE30 and 998ADE35 to accommodate different underlying services (POTS and ISDN), and different US0 bandwidths. + +**Table B.1 – Band-edge frequencies for European VDSL2 band plans** + +| Band plan | Band-edge frequencies
(as defined in the generic band plan in clause 7.1.2) | | | | | | | | | | | +|-----------|--------------------------------------------------------------------------------|-----------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------| +| | $f_{0L}$
kHz | $f_{0H}$
kHz | $f_1$
kHz | $f_2$
kHz | $f_3$
kHz | $f_4$
kHz | $f_5$
kHz | $f_6$
kHz | $f_7$
kHz | $f_8$
kHz | $f_9$
kHz | +| | US0 | | DS1 | | US1 | DS2 | US2 | DS3 | | US3 | DS4 | +| 997 | 25 | 138 | 138 | 3 000 | 5 100 | 7 050 | 12 000 | N/A | N/A | N/A | N/A | +| | 25 | 276 | 276 | | | | | | | | | +| 997E17 | 25 | 138 | 138 | 3 000 | 5 100 | 7 050 | 12 000 | 14 000 | 17 664 | N/A | N/A | +| 997E30 | N/A | N/A | 138 | 3 000 | 5 100 | 7 050 | 12 000 | 14 000 | 19 500 | 27 000 | 30 000 | +| | US0 | | DS1 | | US1 | DS2 | US2 | US3 | | DS3 | US4 | +| 998 | 25 | 138 | 138 | 3 750 | 5 200 | 8 500 | 12 000 | N/A | N/A | N/A | N/A | +| | 25 | 276 | 276 | | | | | | | | | +| | 120 | 276 | 276 | | | | | | | | | +| | N/A | N/A | 138 | | | | | | | | | +| 998E17 | N/A | N/A | 138 | 3 750 | 5 200 | 8 500 | 12 000 | 14 000 | 17 664 | N/A | N/A | +| | N/A | N/A | 276 | | | | | | | | | +| | 25 | 138 | 138 | | | | | | | | | +| 998E30 | N/A | N/A | 138 | 3 750 | 5 200 | 8 500 | 12 000 | 14 000 | 21 450 | 24 890 | 30 000 | +| | N/A | N/A | 276 | | | | | | | | | +| 998E35 | 25 | 138 | 138 | 3 750 | 5 200 | 8 500 | 12 000 | 14 000 | 35 328 | N/A | N/A | +| | US0 | | DS1 | | US1 | DS2 | US2 | DS3 | | US3 | | +| 998ADE17 | 25 | 138 | 138 | 3 750 | 5 200 | 8 500 | 12 000 | 17 664 | | N/A | | +| | 120 | 276 | 276 | | | | | | | | | +| | 25 | 276 | 276 | | | | | | | | | + +**Table B.1 – Band-edge frequencies for European VDSL2 band plans** + +| Band plan | Band-edge frequencies
(as defined in the generic band plan in clause 7.1.2) | | | | | | | | | | | +|-----------|--------------------------------------------------------------------------------|-----------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------| +| | $f_{0L}$
kHz | $f_{0H}$
kHz | $f_1$
kHz | $f_2$
kHz | $f_3$
kHz | $f_4$
kHz | $f_5$
kHz | $f_6$
kHz | $f_7$
kHz | $f_8$
kHz | $f_9$
kHz | +| | N/A | N/A | 276 | | | | | | | | | +| 998ADE30 | N/A | N/A | 138 | 3 750 | 5 200 | 8 500 | 12 000 | 24 890 | | 30 000 | | +| | N/A | N/A | 276 | | | | | | | | | +| 998ADE35 | 25 | 138 | 138 | 3 750 | 5 200 | 8 500 | 12 000 | 35 328 | | N/A | | +| | 120 | 276 | 276 | | | | | | | | | +| | 25 | 276 | 276 | | | | | | | | | + +NOTE 1 – N/A in the columns $f_{0L}$ and $f_{0H}$ designates a band plan variant that does not use US0. + +NOTE 2 – The capability to support US0 together with profile 17a is required for European VDSL2. + +NOTE 3 – The capability to support US0 together with profile 35b is required for European VDSL2. + +The $f_i$ in Table B.1 are defined as follows: + +- $f_{0L}$ and $f_{0H}$ : define lower and upper frequency of US0; +- $f_1$ to $f_5$ are the boundary frequencies of the bands DS1, US1, DS2, US2 as defined for VDSL1 for 997 and 998; +- $f_5$ to $f_9$ are the boundary frequencies for the bands US3, DS3, US4 and DS4 (extended bands); +- The extension of an existing band is considered as a separate band (e.g., 998E17: US3 12 MHz-14 MHz). + +## B.2 Limit PSD mask options + +The Limit PSD mask options defined in this annex are shown in Tables B.2, B.3 and B.4, for various band plans. + +**Table B.2 – European Limit PSD mask options for band plan 997 (and its extensions)** + +| Short name | Limit PSD mask (Long name) | Frequency | | +|------------|----------------------------|---------------------|-----------------------------------------------------| +| | | US0 type A/M (Note) | Highest used upstream or downstream frequency (kHz) | +| B7-1 | 997-M1c-A-7 | A | 7 050 | +| B7-3 | 997-M1x-M | M | 12 000 | +| B7-9 | 997E17-M2x-A | A | 17 664 | +| B7-10 | 997E30-M2x-NUS0 | N/A | 30 000 | + +NOTE – The US0 types stand for: + +- US0 type A corresponds to Annex A of [ITU-T G.992.5]; +- US0 type M corresponds to Annex M of [ITU-T G.992.3] or of [ITU-T G.992.5]; +- US0 type N/A designates a band plan variant that does not use US0. + +**Table B.3 – European limit PSD mask options for band plan 998 (and its extensions)** + +| Short name | Limit PSD mask (Long name) | Frequency | | +|------------|----------------------------|-----------------------|-----------------------------------------------------| +| | | US0 type A/B/M (Note) | Highest used upstream or downstream frequency (kHz) | +| B8-4 | 998-M2x-A | A | 12 000 | +| B8-5 | 998-M2x-M | M | 12 000 | +| B8-6 | 998-M2x-B | B | 12 000 | +| B8-7 | 998-M2x-NUS0 | N/A | 12 000 | +| B8-8 | 998E17-M2x-NUS0 | N/A | 17 664 | +| B8-9 | 998E17-M2x-NUS0-M | N/A | 17 664 | +| B8-10 | 998ADE17-M2x-NUS0-M | N/A | 17 664 | +| B8-11 | 998ADE17-M2x-A | A | 17 664 | +| B8-12 | 998ADE17-M2x-B | B | 17 664 | +| B8-13 | 998E30-M2x-NUS0 | N/A | 30 000 | +| B8-14 | 998E30-M2x-NUS0-M | N/A | 30 000 | +| B8-15 | 998ADE30-M2x-NUS0-M | N/A | 30 000 | +| B8-16 | 998ADE30-M2x-NUS0-A | N/A | 30 000 | +| B8-17 | 998ADE17-M2x-M | M | 17 664 | +| B8-18 | 998E17-M2x-A | A | 17 664 | + +**Table B.3 – European limit PSD mask options for band plan 998 (and its extensions)** + +| Short name | Limit PSD mask
(Long name) | Frequency | | +|------------|-------------------------------|-----------------------------|--------------------------------------------------------------| +| | | US0 type
A/B/M
(Note) | Highest used
upstream or
downstream
frequency (kHz) | +| B8-19 | 998E35-M2x-A | A | 35 328 | +| B8-20 | 998ADE35-M2x-A | A | 35 328 | +| B8-21 | 998ADE35-M2x-B | B | 35 328 | +| B8-22 | 998ADE35-M2x-M | M | 35 328 | + +NOTE – The US0 types stand for: + +- US0 type A corresponds to Annex A of [ITU-T G.992.5]; +- US0 type B corresponds to Annex B of [ITU-T G.992.5]; +- US0 type M corresponds to Annex M of [ITU-T G.992.3] or of [ITU-T G.992.5]; +- US0 type N/A designates a band plan variant that does not use US0; +- 998ADExx-M2x-NUS0-M designate the variants in which DS1 starts at 276 kHz instead of 138 kHz. + +### B.2.1 General requirements in the band below 4 kHz + +The noise in the voice band measured with psophometric weighting according to [ITU-T O.41] clause 3.3 shall not exceed –68 dBm. The psophometer shall be used in bridging mode and shall be calibrated for 600-ohm termination. + +## B.2.2 VTU-R Limit PSD masks for band plan 997 (and its extensions) + +The VTU-R limit PSD masks for band plan 997 (and its extensions) are shown in Table B.4. + +**Table B.4 – VTU-R limit PSD masks for band plan 997 (and its extensions)** + +| Name | B7-1 | B7-3 | B7-9 | B7-10 | +|-----------|--------------|------------|--------------|-----------------| +| Long name | 997-M1-c-A-7 | 997-M1-x-M | 997E17-M2x-A | 997E30-M2x-NUS0 | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 0 | -97.5 | -97.5 | -97.5 | -100 | +| 4 | -97.5 | -97.5 | -97.5 | -100 | +| 4 | -92.5 | -92.5 | -97.5 | -100 | +| 25.875 | -34.5 | -37.5 | -34.5 | -100 | +| 50 | -34.5 | -37.5 | -34.5 | -100 | +| 80 | -34.5 | -37.5 | -34.5 | -100 | +| 120 | -34.5 | -37.5 | -34.5 | -100 | +| 138 | -34.5 | -37.5 | -34.5 | -100 | +| 225 | Interp | -37.5 | Interp | -100 | +| 243 | -93.2 | -37.5 | -93.2 | -100 | +| 276 | Interp | -37.5 | Interp | -100 | +| 493.41 | Interp | -97.9 | Interp | -100 | +| 686 | -100 | -100 | -100 | -100 | +| 2 825 | -100 | -100 | -100 | -100 | +| 3 000 | -80 | -80 | -80 | -80 | +| 3 000 | -56.5 | -56.5 | -50.3 | -50.3 | +| 3 575 | -56.5 | -56.5 | Interp | Interp | +| 3 750 | -56.5 | -56.5 | Interp | Interp | +| 5 100 | -56.5 | -56.5 | -52.6 | -52.6 | +| 5 100 | -80 | -80 | -80 | -80 | +| 5 275 | -100 | -100 | -100 | -100 | +| 6 875 | -100 | -100 | -100 | -100 | +| 7 050 | -100 | -80 | -80 | -80 | +| 7 050 | -100 | -56.5 | -54 | -54 | +| 8 325 | -100 | -56.5 | Interp | Interp | +| 9 950 | -100 | -56.5 | Interp | Interp | +| 10 125 | -100 | -56.5 | -55.5 | -55.5 | +| 10 125 | -100 | -56.5 | -55.5 | -55.5 | +| 11 825 | -100 | -56.5 | -55.5 | -55.5 | +| 12 000 | -100 | -56.5 | -55.5 | -55.5 | +| 12 000 | -100 | -80 | -80 | -80 | +| 12 175 | -100 | -100 | -100 | -100 | +| 13 825 | -100 | -100 | -100 | -100 | +| 14 000 | -100 | -100 | -80 | -80 | + +**Table B.4 – VTU-R limit PSD masks for band plan 997 (and its extensions)** + +| Name | B7-1 | B7-3 | B7-9 | B7-10 | +|-----------|--------------|------------|--------------|-----------------| +| Long name | 997-M1-c-A-7 | 997-M1-x-M | 997E17-M2x-A | 997E30-M2x-NUS0 | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 14 000 | -100 | -100 | -56.5 | -56.5 | +| 14 175 | -100 | -100 | Interp | Interp | +| 17 664 | -100 | -100 | -56.5 | -56.5 | +| 19 500 | -100 | -100 | -80 | -56.5 | +| 19 500 | -100 | -100 | -80 | -80 | +| 19 675 | -100 | -100 | -100 | -100 | +| 21 275 | -100 | -100 | -100 | -100 | +| 21 450 | -100 | -100 | -100 | -100 | +| 21 450 | -100 | -100 | -100 | -100 | +| 24 890 | -100 | -100 | -100 | -100 | +| 24 890 | -100 | -100 | -100 | -100 | +| 25 065 | -100 | -100 | -100 | -100 | +| 26 825 | -100 | -100 | -100 | -100 | +| 27 000 | -100 | -100 | -100 | -80 | +| 27 000 | -100 | -100 | -100 | -56.5 | +| 30 000 | -100 | -100 | -100 | -56.5 | +| 30 000 | -110 | -110 | -110 | -80 | +| 30 175 | -110 | -110 | -110 | -110 | +| > 30 175 | -110 | -110 | -110 | -110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: +– below 2 825 kHz on a dB/log(*f*) basis; and +– above 2 825 kHz on a dB/*f* basis. + +### B.2.3 VTU-O Limit PSD masks for band plans 997 (and its extensions) + +The VTU-O limit PSD masks for band plan 997 (and its extensions) are shown in Table B.5. + +**Table B.5 – VTU-O Limit PSD masks for band plan 997 (and its extensions)** + +| Name | B7-1 | B7-3 | B7-9 | B7-10 | +|-----------|--------------|------------|--------------|-----------------| +| Long name | 997-M1-c-A-7 | 997-M1-x-M | 997E17-M2x-A | 997E30-M2x-NUS0 | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 0 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -92.5 | -92.5 | -92.5 | -92.5 | +| 80 | -72.5 | -92.5 | -72.5 | -72.5 | + +**Table B.5 – VTU-O Limit PSD masks for band plan 997 (and its extensions)** + +| Name | B7-1 | B7-3 | B7-9 | B7-10 | +|-----------|-------------|-----------|--------------|-----------------| +| Long name | 997-M1c-A-7 | 997-M1x-M | 997E17-M2x-A | 997E30-M2x-NUS0 | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 101.2 | Interp | -92.5 | Interp | Interp | +| 138 | -49.5 | Interp | -44.2 | -44.2 | +| 138 | -49.5 | Interp | -36.5 | -36.5 | +| 227.11 | -49.5 | -62 | -36.5 | -36.5 | +| 276 | -49.5 | -48.5 | -36.5 | -36.5 | +| 276 | -49.5 | -36.5 | -36.5 | -36.5 | +| 1 104 | -49.5 | -36.5 | -36.5 | -36.5 | +| 1 622 | -49.5 | -46.5 | -46.5 | -46.5 | +| 2 208 | -49.5 | -48 | Interp | Interp | +| 2 236 | -49.5 | Interp | Interp | Interp | +| 2 249 | -49.5 | -49.5 | Interp | Interp | +| 2 423 | -56.5 | Interp | Interp | Interp | +| 2 500 | -56.5 | -56.5 | Interp | Interp | +| 3 000 | -56.5 | -56.5 | -49.6 | -49.6 | +| 3 000 | -80 | -80 | -80 | -80 | +| 3 175 | -100 | -100 | -100 | -100 | +| 4 925 | -100 | -100 | -100 | -100 | +| 5 100 | -80 | -80 | -80 | -80 | +| 5 100 | -56.5 | -56.5 | -52.6 | -52.6 | +| 5 200 | -56.5 | -56.5 | Interp | Interp | +| 6 875 | -56.5 | -56.5 | Interp | Interp | +| 7 050 | -56.5 | -56.5 | -54 | -54 | +| 7 050 | -80 | -80 | -80 | -80 | +| 7 225 | -100 | -100 | -100 | -100 | +| 10 125 | -100 | -100 | -100 | -100 | +| 10 125 | -100 | -100 | -100 | -100 | +| 10 300 | -100 | -100 | -100 | -100 | +| 11 825 | -100 | -100 | -100 | -100 | +| 12 000 | -100 | -100 | -80 | -80 | +| 12 000 | -100 | -100 | -56.5 | -56.5 | +| 13 825 | -100 | -100 | -56.5 | -56.5 | +| 14 000 | -100 | -100 | -56.5 | -56.5 | +| 14 000 | -100 | -100 | -80 | -80 | +| 14 175 | -100 | -100 | -100 | -100 | +| 17 489 | -100 | -100 | -100 | -100 | +| 17 664 | -100 | -100 | -100 | -100 | +| 17 664 | -100 | -100 | -100 | -100 | + +**Table B.5 – VTU-O Limit PSD masks for band plan 997 (and its extensions)** + +| Name | B7-1 | B7-3 | B7-9 | B7-10 | +|-----------|-------------|-----------|--------------|-----------------| +| Long name | 997-M1c-A-7 | 997-M1x-M | 997E17-M2x-A | 997E30-M2x-NUS0 | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 19 325 | -100 | -100 | -100 | -100 | +| 19 500 | -100 | -100 | -100 | -80 | +| 19 500 | -100 | -100 | -100 | -56.5 | +| 21 000 | -100 | -100 | -100 | -56.5 | +| 21 450 | -100 | -100 | -100 | -56.5 | +| 21 450 | -100 | -100 | -100 | -56.5 | +| 21 625 | -100 | -100 | -100 | -56.5 | +| 24 715 | -100 | -100 | -100 | -56.5 | +| 24 890 | -100 | -100 | -100 | -56.5 | +| 24 890 | -100 | -100 | -100 | -56.5 | +| 27 000 | -100 | -100 | -100 | -56.5 | +| 27 000 | -100 | -100 | -100 | -80 | +| 27 175 | -100 | -100 | -100 | -100 | +| 30 000 | -100 | -100 | -100 | -100 | +| 30 000 | -110 | -110 | -110 | -110 | +| 30 175 | -110 | -110 | -110 | -110 | +| > 30 175 | -110 | -110 | -110 | -110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: + +- below $f_i$ on a $\text{dB}/\log(f)$ basis; and +- above $f_i$ on a $\text{dB}/f$ basis. + +### B.2.4 VTU-R limit PSD masks for band plan 998 (and its extensions) + +The VTU-R limit PSD masks for band plan 998 (and its extensions) with a highest used upstream or downstream frequency of 12 MHz or 17.664 MHz (see Table B.3 for the band plan 998 PSD mask options) are shown in Table B.6A. + +**Table B.6A – VTU-R limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 12 MHz or 17.664 MHz** + +| Name | B8-4 | B8-5 | B8-6 | B8-7 | B8-8 | B8-9 | B8-10 | B8-11 | B8-12 | B8-17 | B8-18 | +|------------------|------------------|------------------|------------------|---------------------|-------------------------|---------------------------|-----------------------------|------------------------|------------------------|------------------------|----------------------| +| Long name | 998-M2x-A | 998-M2x-M | 998-M2x-B | 998-M2x-NUS0 | 998-E17-M2x-NUS0 | 998-E17-M2x-NUS0-M | 998-ADE17-M2x-NUS0-M | 998-ADE17-M2x-A | 998-ADE17-M2x-B | 998-ADE17-M2x-M | 998-E17-M2x-A | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 0 | –97.5 | –97.5 | –97.5 | –100 | –100 | –100 | –100 | –97.5 | –97.5 | –97.5 | –97.5 | +| 4 | –97.5 | –97.5 | –97.5 | –100 | –100 | –100 | –100 | –97.5 | –97.5 | –97.5 | –97.5 | +| 4 | –92.5 | –92.5 | –92.5 | –100 | –100 | –100 | –100 | –92.5 | –92.5 | –92.5 | –92.5 | +| 25.875 | –34.5 | –37.5 | –92.5 | –100 | –100 | –100 | –100 | –34.5 | –92.5 | –37.5 | –34.5 | +| 50 | –34.5 | –37.5 | –90 | –100 | –100 | –100 | –100 | –34.5 | –90 | –37.5 | –34.5 | +| 80 | –34.5 | –37.5 | –81.8 | –100 | –100 | –100 | –100 | –34.5 | –81.8 | –37.5 | –34.5 | +| 120 | –34.5 | –37.5 | –34.5 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –37.5 | –34.5 | +| 138 | –34.5 | –37.5 | –34.5 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –37.5 | –34.5 | +| 225 | Interp | –37.5 | –34.5 | –100 | –100 | –100 | –100 | Interp | –34.5 | –37.5 | Interp | +| 243 | –93.2 | –37.5 | –34.5 | –100 | –100 | –100 | –100 | –93.2 | –34.5 | –37.5 | –93.2 | +| 276 | Interp | –37.5 | –34.5 | –100 | –100 | –100 | –100 | Interp | –34.5 | –37.5 | Interp | +| 493.41 | Interp | –97.9 | Interp | –100 | –100 | –100 | –100 | Interp | Interp | –97.9 | Interp | +| 508.8 | Interp | Interp | –98 | –100 | –100 | –100 | –100 | Interp | –98 | Interp | Interp | +| 686 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 3 575 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 3 750 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 3 750 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | +| 5 200 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | + +**Table B.6A – VTU-R limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 12 MHz or 17.664 MHz** + +| Name | B8-4 | B8-5 | B8-6 | B8-7 | B8-8 | B8-9 | B8-10 | B8-11 | B8-12 | B8-17 | B8-18 | +|-----------|-----------|-----------|-----------|--------------|------------------|--------------------|----------------------|-----------------|-----------------|-----------------|---------------| +| Long name | 998-M2x-A | 998-M2x-M | 998-M2x-B | 998-M2x-NUS0 | 998-E17-M2x-NUS0 | 998-E17-M2x-NUS0-M | 998-ADE17-M2x-NUS0-M | 998-ADE17-M2x-A | 998-ADE17-M2x-B | 998-ADE17-M2x-M | 998-E17-M2x-A | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 5 200 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | +| 5 375 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 8 325 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 8 500 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | +| 8 500 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | +| 10 000 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | +| 12 000 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | -55.5 | +| 12 000 | -80 | -80 | -80 | -80 | -56.5 | -56.5 | -80 | -80 | -80 | -80 | -56.5 | +| 12 175 | -100 | -100 | -100 | -100 | -56.5 | -56.5 | -100 | -100 | -100 | -100 | -56.5 | +| 14 000 | -100 | -100 | -100 | -100 | -56.5 | -56.5 | -100 | -100 | -100 | -100 | -56.5 | +| 14 000 | -100 | -100 | -100 | -100 | -80 | -80 | -100 | -100 | -100 | -100 | -80 | +| 14 175 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 21 275 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 30 000 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 30 000 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| 30 175 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| > 30 175 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: +– below 3 575 kHz on a dB/log(*f*) basis; and +– above 3 575 kHz on a dB/*f* basis. + +The VTU-R limit PSD masks for band plan 998 (and its extensions) with a highest used upstream or downstream frequency of 30 MHz or 35.328 MHz (see Table B.3 for the band plan 998 PSD mask options) are shown in Table B.6B. + +**Table B.6B – VTU-R limit PSD masks for band plan 998 (and its extensions) +with highest used frequency of 30 MHz or 35.328 MHz** + +| Name | B8-13 | B8-14 | B8-15 | B8-16 | B8-19 | B8-20 | B8-21 | B8-22 | +|------------------|---------------------------------------|-----------------------------------------|-------------------------------------------|-------------------------------------------|-------------------------------|---------------------------------|---------------------------------|---------------------------------| +| Long name | 998
E30-
M2x-
NUS0 | 998
E30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-A | 998
E35-
M2x-A | 998
ADE35-
M2x-A | 998
ADE35-
M2x-B | 998
ADE35-
M2x-M | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| 0 | –100 | –100 | –100 | –100 | –97.5 | –97.5 | –97.5 | –97.5 | +| 4 | –100 | –100 | –100 | –100 | –97.5 | –97.5 | –97.5 | –97.5 | +| 4 | –100 | –100 | –100 | –100 | –92.5 | –92.5 | –92.5 | –92.5 | +| 25.875 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –92.5 | –37.5 | +| 50 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –90 | –37.5 | +| 80 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –81.8 | –37.5 | +| 120 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –34.5 | –37.5 | +| 138 | –100 | –100 | –100 | –100 | –34.5 | –34.5 | –34.5 | –37.5 | +| 225 | –100 | –100 | –100 | –100 | Interp | Interp | –34.5 | –37.5 | +| 243 | –100 | –100 | –100 | –100 | –93.2 | –93.2 | –34.5 | –37.5 | +| 276 | –100 | –100 | –100 | –100 | Interp | Interp | –34.5 | –37.5 | +| 493.41 | –100 | –100 | –100 | –100 | Interp | –97.9 | Interp | –97.9 | +| 508.8 | –100 | –100 | –100 | –100 | Interp | Interp | –98 | Interp | +| 686 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 3 575 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 3 750 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 3 750 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | +| 5 100 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 5 200 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | +| 5 200 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 5 375 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | + +**Table B.6B – VTU-R limit PSD masks for band plan 998 (and its extensions) +with highest used frequency of 30 MHz or 35.328 MHz** + +| Name | B8-13 | B8-14 | B8-15 | B8-16 | B8-19 | B8-20 | B8-21 | B8-22 | +|----------------------|---------------------------------------|-----------------------------------------|-------------------------------------------|-------------------------------------------|-------------------------------|---------------------------------|---------------------------------|---------------------------------| +| Long
name | 998
E30-
M2x-
NUS0 | 998
E30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-A | 998
E35-
M2x-A | 998
ADE35-
M2x-A | 998
ADE35-
M2x-B | 998
ADE35-
M2x-M | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| 8 325 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 8 500 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 8 500 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | +| 10 000 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | +| 12 000 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | +| 12 000 | –56.5 | –56.5 | –80 | –80 | –56.5 | –80 | –80 | –80 | +| 12 175 | –56.5 | –56.5 | –100 | –100 | –56.5 | –100 | –100 | –100 | +| 14 000 | –56.5 | –56.5 | –100 | –100 | –56.5 | –100 | –100 | –100 | +| 14 000 | –80 | –80 | –100 | –100 | –80 | –100 | –100 | –100 | +| 14 175 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 21 275 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 21 450 | –80 | –80 | –100 | –100 | –100 | –100 | –100 | –100 | +| 21 450 | –56.5 | –56.5 | –100 | –100 | –100 | –100 | –100 | –100 | +| 24 715 | –56.5 | –56.5 | –100 | –100 | –100 | –100 | –100 | –100 | +| 24 890 | –56.5 | –56.5 | –80 | –80 | –100 | –100 | –100 | –100 | +| 24 890 | –80 | –80 | –56.5 | –56.5 | –100 | –100 | –100 | –100 | +| 25 065 | –100 | –100 | –56.5 | –56.5 | –100 | –100 | –100 | –100 | +| 30 000 | –100 | –100 | –56.5 | –56.5 | –100 | –100 | –100 | –100 | +| 30 000 | –110 | –110 | –80 | –80 | –110 | –110 | –110 | –110 | +| 30 175 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | +| 35 328 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | +| > 35 328 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | + +**Table B.6B – VTU-R limit PSD masks for band plan 998 (and its extensions) +with highest used frequency of 30 MHz or 35.328 MHz** + +| Name | B8-13 | B8-14 | B8-15 | B8-16 | B8-19 | B8-20 | B8-21 | B8-22 | +|-----------|-----------------------------|-------------------------------|---------------------------------|---------------------------------|----------------------|------------------------|------------------------|------------------------| +| Long name | 998
E30-
M2x-
NUS0 | 998
E30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-A | 998
E35-
M2x-A | 998
ADE35-
M2x-A | 998
ADE35-
M2x-B | 998
ADE35-
M2x-M | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: +– below 3 575 kHz on a dB/log(*f*) basis; and +– above 3 575 kHz on a dB/*f* basis. + +### B.2.5 VTU-O Limit PSD masks for band plan 998 (and its extensions) + +The VTU-O limit PSD masks for band plan 998 (and its extensions) with a highest used upstream or downstream frequency of 12 MHz or 17.664 MHz (see Table B.3 for the band plan 998 PSD mask options) are shown in Table B.7A. + +**Table B.7A– VTU-O limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 12 MHz or 17.664 MHz** + +| Name | B8-4 | B8-5 | B8-6 | B8-7 | B8-8 | B8-9 | B8-10 | B8-11 | B8-12 | B8-17 | B8-18 | +|-----------|---------------|---------------|---------------|----------------------|-----------------------------|-------------------------------|---------------------------------|------------------------|------------------------|------------------------|----------------------| +| Long name | 998-
M2x-A | 998-
M2x-M | 998-
M2x-B | 998-
M2x-
NUS0 | 998
E17-
M2x-
NUS0 | 998
E17-
M2x-
NUS0-M | 998
ADE17-
M2x-
NUS0-M | 998
ADE17-
M2x-A | 998
ADE17-
M2x-B | 998
ADE17-
M2x-M | 998
E17-
M2x-A | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| 0 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | +| 80 | -72.5 | -92.5 | -92.5 | -72.5 | -72.5 | -92.5 | -92.5 | -72.5 | -92.5 | -92.5 | -72.5 | + +**Table B.7A – VTU-O limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 12 MHz or 17.664 MHz** + +| Name | B8-4 | B8-5 | B8-6 | B8-7 | B8-8 | B8-9 | B8-10 | B8-11 | B8-12 | B8-17 | B8-18 | +|------------------|-----------------------|-----------------------|-----------------------|-------------------------------|---------------------------------------|-----------------------------------------|-------------------------------------------|---------------------------------|---------------------------------|---------------------------------|-------------------------------| +| Long name | 998-
M2x-A | 998-
M2x-M | 998-
M2x-B | 998-
M2x-
NUS0 | 998
E17-
M2x-
NUS0 | 998
E17-
M2x-
NUS0-M | 998
ADE17-
M2x-
NUS0-M | 998
ADE17-
M2x-A | 998
ADE17-
M2x-B | 998
ADE17-
M2x-M | 998
E17-
M2x-A | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| 101.2 | Interp | -92.5 | -92.5 | Interp | Interp | -92.5 | -92.5 | Interp | -92.5 | -92.5 | Interp | +| 138 | -44.2 | Interp | Interp | -44.2 | -44.2 | Interp | Interp | -44.2 | Interp | Interp | -44.2 | +| 138 | -36.5 | Interp | Interp | -36.5 | -36.5 | Interp | Interp | -36.5 | Interp | Interp | -36.5 | +| 227.11 | -36.5 | -62 | -62 | -36.5 | -36.5 | -62 | -62 | -36.5 | -62 | -62 | -36.5 | +| 276 | -36.5 | -48.5 | -48.5 | -36.5 | -36.5 | -48.5 | -48.5 | -36.5 | -48.5 | -48.5 | -36.5 | +| 276 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | +| 1 104 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | -36.5 | +| 1 622 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | -46.5 | +| 2 208 | -48 | -48 | -48 | -48 | -48 | -48 | -48 | -48 | -48 | -48 | -48 | +| 2 249 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 2 500 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 3 750 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | -51.2 | +| 3 750 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | +| 3 925 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 5 025 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 5 200 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | +| 5 200 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | -52.7 | +| 8 500 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | -54.8 | +| 8 500 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | +| 8 675 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 11 825 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | + +**Table B.7A– VTU-O limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 12 MHz or 17.664 MHz** + +| Name | B8-4 | B8-5 | B8-6 | B8-7 | B8-8 | B8-9 | B8-10 | B8-11 | B8-12 | B8-17 | B8-18 | +|-----------|-----------|-----------|-----------|--------------|------------------|--------------------|----------------------|-----------------|-----------------|-----------------|---------------| +| Long name | 998-M2x-A | 998-M2x-M | 998-M2x-B | 998-M2x-NUS0 | 998-E17-M2x-NUS0 | 998-E17-M2x-NUS0-M | 998-ADE17-M2x-NUS0-M | 998-ADE17-M2x-A | 998-ADE17-M2x-B | 998-ADE17-M2x-M | 998-E17-M2x-A | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 12 000 | -100 | -100 | -100 | -100 | -100 | -100 | -80 | -80 | -80 | -80 | -100 | +| 12 000 | -100 | -100 | -100 | -100 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | -100 | +| 13 825 | -100 | -100 | -100 | -100 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | -100 | +| 14 000 | -100 | -100 | -100 | -100 | -80 | -80 | -56.5 | -56.5 | -56.5 | -56.5 | -80 | +| 14 000 | -100 | -100 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 17 664 | -100 | -100 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 21 000 | -100 | -100 | -100 | -100 | -80 | -80 | -80 | -80 | -80 | -80 | -80 | +| 21 450 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 30 000 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 30 000 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| 30 175 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| > 30 175 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: + +- below $f_i$ on a dB/log( $f$ ) basis; and +- above $f_i$ on a dB/ $f$ basis, + +where $f_i$ is defined in Table B.1 as either 138 kHz or 276 kHz. + +The VTU-O limit PSD masks for band plan 998 (and its extensions) with a highest used upstream or downstream frequency of 30 MHz or 35.328 MHz (see Table B.3 for the band plan 998 PSD mask options) are shown in Table B.7B. + +**Table B.7B – VTU-O limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 30 MHz or 35.328 MHz** + +| Name | B8-13 | B8-14 | B8-15 | B8-16 | B8-19 | B8-20 | B8-21 | B8-22 | +|------------------|---------------------------------------|-----------------------------------------|-------------------------------------------|-------------------------------------------|-------------------------------|---------------------------------|---------------------------------|---------------------------------| +| Long name | 998
E30-
M2x-
NUS0 | 998
E30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-A | 998
E35-
M2x-A | 998
ADE35-
M2x-A | 998
ADE35-
M2x-B | 998
ADE35-
M2x-M | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| 0 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | +| 4 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | –97.5 | +| 4 | –92.5 | –92.5 | –92.5 | –92.5 | –92.5 | –92.5 | –92.5 | –92.5 | +| 80 | –72.5 | –92.5 | –92.5 | –72.5 | –72.5 | –72.5 | –92.5 | –92.5 | +| 101.2 | Interp | –92.5 | –92.5 | Interp | Interp | Interp | –92.5 | –92.5 | +| 138 | –44.2 | Interp | Interp | –44.2 | –44.2 | –44.2 | Interp | Interp | +| 138 | –36.5 | Interp | Interp | –36.5 | –36.5 | –36.5 | Interp | Interp | +| 227.11 | –36.5 | –62 | –62 | –36.5 | –36.5 | –36.5 | –62 | –62 | +| 276 | –36.5 | –48.5 | –48.5 | –36.5 | –36.5 | –36.5 | –48.5 | –48.5 | +| 276 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | +| 1 104 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | +| 1 622 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | +| 2 208 | –48 | –48 | –48 | –48 | –48 | –48 | –48 | –48 | +| 3 750 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | +| 3 750 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 3 925 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 5 025 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 5 200 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 5 200 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | +| 8 500 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | +| 8 500 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 8 675 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | + +**Table B.7B – VTU-O limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 30 MHz or 35.328 MHz** + +| Name | B8-13 | B8-14 | B8-15 | B8-16 | B8-19 | B8-20 | B8-21 | B8-22 | +|-----------|-----------------------------|-------------------------------|---------------------------------|---------------------------------|----------------------|------------------------|------------------------|------------------------| +| Long name | 998
E30-
M2x-
NUS0 | 998
E30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-A | 998
E35-
M2x-A | 998
ADE35-
M2x-A | 998
ADE35-
M2x-B | 998
ADE35-
M2x-M | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| 11 825 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 12 000 | -100 | -100 | -80 | -80 | -100 | -80 | -80 | -80 | +| 12 000 | -100 | -100 | -56.5 | -56.5 | -100 | -56.5 | -56.5 | -56.5 | +| 13 825 | -100 | -100 | -56.5 | -56.5 | -100 | -56.5 | -56.5 | -56.5 | +| 14 000 | -80 | -80 | -56.5 | -56.5 | -80 | -56.5 | -56.5 | -56.5 | +| 14 000 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 21 450 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 21 450 | -80 | -80 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 21 625 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 24 715 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 24 890 | -80 | -80 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | -56.5 | +| 24 890 | -56.5 | -56.5 | -80 | -80 | -56.5 | -56.5 | -56.5 | -56.5 | +| 25 065 | -56.5 | -56.5 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | +| 30 000 | -56.5 | -56.5 | -100 | -100 | -56.5 | -56.5 | -56.5 | -56.5 | +| 30 000 | -80 | -80 | -110 | -110 | -73 | -73 | -73 | -73 | +| 30 175 | -110 | -110 | -110 | -110 | Interp | Interp | Interp | Interp | +| 35 328 | -110 | -110 | -110 | -110 | -73.4 | -73.4 | -73.4 | -73.4 | +| 37 000 | -110 | -110 | -110 | -110 | -83 | -83 | -83 | -83 | +| 40 656 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| > 40 656 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: + +**Table B.7B – VTU-O limit PSD masks for band plan 998 (and its extensions) +with a highest used frequency of 30 MHz or 35.328 MHz** + +| Name | B8-13 | B8-14 | B8-15 | B8-16 | B8-19 | B8-20 | B8-21 | B8-22 | +|-------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------|-----------------------------------------|-------------------------------------------|-------------------------------------------|-------------------------------|---------------------------------|---------------------------------|---------------------------------| +| Long
name | 998
E30-
M2x-
NUS0 | 998
E30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-M | 998
ADE30-
M2x-
NUS0-A | 998
E35-
M2x-A | 998
ADE35-
M2x-A | 998
ADE35-
M2x-B | 998
ADE35-
M2x-M | +| kHz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | dBm/
Hz | +| – below $f_i$ on a dB/log( $f$ ) basis; and
– above $f_i$ on a dB/ $f$ basis,
where $f_i$ is defined in Table B.1 as either 138 kHz or 276 kHz. | | | | | | | | | + +### **B.3 UPBO reference PSDs** + +UPBO parameters '*a*' and '*b*' are set by network management. + +NOTE – The parameters '*a*' and '*b*' are expected to be uniform across all lines sharing a section of cable plant. + +### **B.4 Template PSD** + +#### **B.4.1 Definition** + +The Template PSD is set to 3.5 dB below the PSD mask in frequency bands in which the PSD is at or above $-96.5$ dBm/Hz. Elsewhere the template is set to $-100$ dBm/Hz below 4 MHz, $-110$ dBm/Hz between 4 MHz and $f_3$ , or $-112$ dBm/Hz between $f_3$ and 35.328 MHz, where $f_3$ is defined in Table B.1. These values are chosen to satisfy the requirements of clause 7.2.2. + +#### **B.4.2 Narrow-band PSD verification** + +Narrow-band compliance with the PSD masks in this annex shall be verified by power measurements using a 10-kHz measurement bandwidth centred on the frequency in question above 4 kHz, and in a 100-Hz measurement bandwidth in the band up to 4 kHz. + +#### **B.4.3 Use in simulation (Informative)** + +The Template PSD may be used in simulations of VDSL2 performance as representative of an average transmitter conformant with the associated Limit PSD mask. + +### **B.5 Compliance** + +Compliance requires conformance with at least one Limit PSD mask. + +## Annex C + +### Region C (Japan) + +(This annex forms an integral part of this Recommendation.) + +#### C.1 Band plan + +The band plan shall be specified as shown in Figure C.1. According to the profiles defined in Table 6-1, adequate subsets of US0, DS1, US1, DS2, US2, DS3, and US3 shall be selected. The transition frequency between US0 and DS1 is 138 kHz or 276 kHz as defined in C.2.1. + +![Figure C.1: Band plan diagram showing frequency bands for US0, DS1, US1, DS2, US2, DS3, and US3. The x-axis represents frequency in MHz, ranging from 0.025 to 30 MHz. The bands are: US0 (0.025 to 0.138 MHz, shaded), DS1 (0.138 to 3.75 MHz), US1 (3.75 to 5.2 MHz), DS2 (5.2 to 8.5 MHz), US2 (8.5 to 12 MHz), DS3 (12 to 18.1 MHz), and US3 (18.1 to 30 MHz). Frequency markers are at 0.025, 3.75, 5.2, 8.5, 12, 18.1, and 30 MHz. Reference G.993.2(19)_FC.1 is noted.](2265807a2d69d9b67a570fd640d2eb89_img.jpg) + +Figure C.1: Band plan diagram showing frequency bands for US0, DS1, US1, DS2, US2, DS3, and US3. The x-axis represents frequency in MHz, ranging from 0.025 to 30 MHz. The bands are: US0 (0.025 to 0.138 MHz, shaded), DS1 (0.138 to 3.75 MHz), US1 (3.75 to 5.2 MHz), DS2 (5.2 to 8.5 MHz), US2 (8.5 to 12 MHz), DS3 (12 to 18.1 MHz), and US3 (18.1 to 30 MHz). Frequency markers are at 0.025, 3.75, 5.2, 8.5, 12, 18.1, and 30 MHz. Reference G.993.2(19)\_FC.1 is noted. + +Figure C.1 – The band plan between 25 kHz and 30 MHz + +#### C.2 Limit PSD masks + +##### C.2.1 VDSL2 system operating at frequencies above the POTS band + +The frequencies above 25 kHz are used for VDSL2. The downstream PSD shall comply with the Limit PSD masks defined in Table C.1, Table C.2, Table C.5 or Table C.6 and the upstream PSD shall comply with the Limit PSD masks defined in Table C.3, Table C.4, Table C.7 or Table C.8. Other PSD limitations are for further study. + +Table C.1 – VTU-O limit PSD mask (VDSL2 above POTS band; 25-138 kHz Type(b)) + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|--------------------------|---------------------------------------|----------------------------------------------------------| +| DS1 | $0 < f < 0.12$ | -120 | – | +| | $0.12 \leq f \leq 0.138$ | $-60 + (50/0.018) \times (f - 0.138)$ | – | +| | $0.138 < f < 3.75$ | $-60 + 3.5 (= -56.5)$ | – | +| | $3.75 \leq f \leq 3.925$ | $-80 - (20/0.175) \times (f - 3.75)$ | – | +| | $3.925 < f < 5.025$ | -100 | -50 | +| | $5.025 \leq f \leq 5.2$ | $-80 + (20/0.175) \times (f - 5.2)$ | – | +| DS2 | $5.2 < f < 8.5$ | $-60 + 3.5 (= -56.5)$ | – | +| | $8.5 \leq f \leq 8.675$ | $-80 - (20/0.175) \times (f - 8.5)$ | – | +| | $8.675 < f < 11.825$ | -100 | -52 | +| | $11.825 \leq f \leq 12$ | $-80 + (20/0.175) \times (f - 12)$ | – | + +**Table C.1 – VTU-O limit PSD mask (VDSL2 above POTS band; 25-138 kHz Type(b))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|---------------------------|--------------------------------------|----------------------------------------------------------| +| DS3 | $12 < f < 18.1$ | $-60 + 3.5 (= -56.5)$ | – | +| | $18.1 \leq f \leq 18.275$ | $-80 - (20/0.175) \times (f - 18.1)$ | – | +| | $18.275 < f < 30$ | –100 | –52 | +| | $30 \leq f$ | –110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.2 – VTU-O limit PSD mask (VDSL2 above POTS band; 25-276 kHz Type(b))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|---------------------------|---------------------------------------|----------------------------------------------------------| +| DS1 | $0 < f < 0.12$ | –120 | – | +| | $0.12 \leq f < 0.225$ | –110 | – | +| | $0.225 \leq f \leq 0.276$ | $-60 + (50/0.051) \times (f - 0.276)$ | – | +| | $0.276 < f < 3.75$ | $-60 + 3.5 (= -56.5)$ | – | +| | $3.75 \leq f \leq 3.925$ | $-80 - (20/0.175) \times (f - 3.75)$ | – | +| | $3.925 < f < 5.025$ | –100 | –50 | +| | $5.025 \leq f \leq 5.2$ | $-80 + (20/0.175) \times (f - 5.2)$ | – | +| DS2 | $5.2 < f < 8.5$ | $-60 + 3.5 (= -56.5)$ | – | +| | $8.5 \leq f \leq 8.675$ | $-80 - (20/0.175) \times (f - 8.5)$ | – | +| | $8.675 < f < 11.825$ | –100 | –52 | +| | $11.825 \leq f \leq 12$ | $-80 + (20/0.175) \times (f - 12)$ | – | +| DS3 | $12 < f < 18.1$ | $-60 + 3.5 (= -56.5)$ | – | +| | $18.1 \leq f \leq 18.275$ | $-80 - (20/0.175) \times (f - 18.1)$ | – | +| | $18.275 < f < 30$ | –100 | –52 | +| | $30 \leq f$ | –110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.3 – VTU-R Limit PSD mask (VDSL2 above POTS band; 25-138 kHz Type(b))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|------------------------------|---------------------------------------|----------------------------------------------------------| +| US0 | $0 < f < 0.004$ | -97.5 | – | +| | $0.004 \leq f \leq 0.025875$ | $-92.5 + 13.4 \times \log_2(f/0.004)$ | – | +| | $0.025875 < f < 0.138$ | $-60 + 3.5 (= -56.5)$ | – | +| | $0.138 \leq f \leq 0.210$ | $-56.5 - 72 \times \log_2(f/0.138)$ | – | +| | $0.210 < f < 3.575$ | 100 | – | +| | $3.575 \leq f \leq 3.75$ | $-80 + (20/0.175) \times (f - 3.75)$ | – | +| US1 | $3.75 < f < 5.2$ | $-60 + 3.5 (= -56.5)$ | – | +| | $5.2 \leq f \leq 5.375$ | $-80 - (20/0.175) \times (f - 5.2)$ | – | +| | $5.375 < f < 8.325$ | -100 | -52 | +| | $8.325 \leq f \leq 8.5$ | $-80 + (20/0.175) \times (f - 8.5)$ | – | +| US2 | $8.5 < f < 12$ | $-60 + 3.5 (= -56.5)$ | – | +| | $12 \leq f \leq 12.175$ | $-80 - (20/0.175) \times (f - 12)$ | – | +| | $12.175 < f < 17.925$ | -100 | -52 | +| | $17.925 \leq f \leq 18.1$ | $-80 + (20/0.175) \times (f - 18.1)$ | – | +| US3 | $18.1 < f < 30$ | $-60 + 3.5 (= -56.5)$ | – | +| | $30 \leq f \leq 30.175$ | $-80 - (30/0.175) \times (f - 30)$ | – | +| | $30.175 < f$ | -110 | – | + +NOTE 1 – All PSD and power measurements are in 100 Ω. +NOTE 2 – The limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.4 – VTU-R Limit PSD mask (VDSL2 above POTS band; 25-276 kHz Type(b))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|------------------------------|---------------------------------------|----------------------------------------------------------| +| US0 | $0 < f < 0.004$ | -97.5 | – | +| | $0.004 \leq f \leq 0.025875$ | $-92.5 + 13.4 \times \log_2(f/0.004)$ | – | +| | $0.025875 < f < 0.276$ | $-60 + 3.5 (= -56.5)$ | – | +| | $0.276 \leq f \leq 0.420$ | $-56.5 - 72 \times \log_2(f/0.276)$ | – | +| | $0.420 < f < 3.575$ | -100 | – | +| | $3.575 \leq f \leq 3.75$ | $-80 + (20/0.175) \times (f - 3.75)$ | – | +| US1 | $3.75 < f < 5.2$ | $-60 + 3.5 (= -56.5)$ | – | +| | $5.2 \leq f \leq 5.375$ | $-80 - (20/0.175) \times (f - 5.2)$ | – | +| | $5.375 < f < 8.325$ | -100 | -52 | +| | $8.325 \leq f \leq 8.5$ | $-80 + (20/0.175) \times (f - 8.5)$ | – | +| US2 | $8.5 < f < 12$ | $-60 + 3.5 (= -56.5)$ | – | +| | $12 \leq f \leq 12.175$ | $-80 - (20/0.175) \times (f - 12)$ | – | +| | $12.175 < f < 17.925$ | -100 | -52 | +| | $17.925 \leq f \leq 18.1$ | $-80 + (20/0.175) \times (f - 18.1)$ | – | +| US3 | $18.1 < f < 30$ | $-60 + 3.5 (= -56.5)$ | – | +| | $30 \leq f \leq 30.175$ | $-80 - (30/0.175) \times (f - 30)$ | – | +| | $30.175 < f$ | -110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.5 – VTU-O Limit PSD mask (VDSL2 above POTS band; 25-138 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|--------------------------|---------------------------------------|----------------------------------------------------------| +| DS1 | $0 < f < 0.004$ | -97.5 | – | +| | $0.004 \leq f < 0.08$ | $-92.5 + 4.63 \times \log_2(f/0.004)$ | – | +| | $0.08 \leq f \leq 0.138$ | $-72.5 + 36 \times \log_2(f/0.08)$ | – | +| | $0.138 < f \leq 1.104$ | $-40 + 3.5 (= -36.5)$ | – | +| | $1.104 < f < 1.622$ | $-36.5 - 18 \times \log_2(f/1.104)$ | – | +| | $1.622 \leq f < 3.75$ | $-46.5 - 2.9 \times \log_2(f/1.622)$ | – | +| | $3.75 \leq f \leq 3.925$ | $-80 - (20/0.175) \times (f - 3.75)$ | – | +| | $3.925 < f < 5.025$ | -100 | -50 | +| | $5.025 \leq f \leq 5.2$ | $-80 + (20/0.175) \times (f - 5.2)$ | – | +| DS2 | $5.2 < f < 8.5$ | $-55 + 3.5 (= -51.5)$ | – | +| | $8.5 \leq f \leq 8.675$ | $-80 - (20/0.175) \times (f - 8.5)$ | – | +| | $8.675 < f < 30$ | -100 | -52 | +| | $30 \leq f$ | -110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.6 – VTU-O Limit PSD mask (VDSL2 above POTS band; 25-276 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|----------------------------|--------------------------------------|----------------------------------------------------------| +| DS1 | $0 < f < 0.004$ | -97.5 | – | +| | $0.004 \leq f < 0.1012$ | -90 | – | +| | $0.1012 \leq f < 0.2271$ | $-90 + 24 \times \log_2(f/0.1012)$ | – | +| | $0.2271 \leq f \leq 0.276$ | $-62 + 63 \times \log_2(f/0.2271)$ | – | +| | $0.276 < f \leq 1.104$ | $-40 + 3.5 (= -36.5)$ | – | +| | $1.104 < f < 1.622$ | $-36.5 - 18 \times \log_2(f/1.104)$ | – | +| | $1.622 \leq f < 3.75$ | $-46.5 - 2.9 \times \log_2(f/1.622)$ | – | +| | $3.75 \leq f \leq 3.925$ | $-80 - (20/0.175) \times (f - 3.75)$ | – | +| | $3.925 < f < 5.025$ | -100 | -50 | +| | $5.025 \leq f \leq 5.2$ | $-80 + (20/0.175) \times (f - 5.2)$ | – | + +**Table C.6 – VTU-O Limit PSD mask (VDSL2 above POTS band; 25-276 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|--------------------------|-------------------------------------|----------------------------------------------------------| +| DS2 | $5.2 < f < 8.5$ | $-55 + 3.5 (= -51.5)$ | – | +| | $8.5 \leq f \leq 8.675$ | $-80 - (20/0.175) \times (f - 8.5)$ | – | +| | $8.675 < f < 30$ | –100 | –52 | +| | $30 \leq f$ | –110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.7 – VTU-R Limit PSD mask (VDSL2 above POTS bands; 25-138 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|------------------------------|------------------------------------------|----------------------------------------------------------| +| US0 | $0 < f < 0.004$ | –97.5 | – | +| | $0.004 \leq f \leq 0.025875$ | $-92.5 + 21.5 \times \log_2(f/0.004)$ | – | +| | $0.025875 < f < 0.138$ | $-38 + 3.5 (= -34.5)$ | – | +| | $0.138 \leq f < 0.24292$ | $-34.5 - 72 \times \log_2(f/0.138)$ | – | +| | $0.24292 \leq f \leq 0.686$ | $-93.2 - 15 \times \log_{10}(f/0.24292)$ | – | +| | $0.686 < f < 3.575$ | –100 | – | +| | $3.575 \leq f \leq 3.75$ | $-80 + (20/0.175) \times (f - 3.75)$ | – | +| US1 | $3.75 < f < 5.2$ | $-53 + 3.5 (= -49.5)$ | – | +| | $5.2 \leq f \leq 5.375$ | $-80 - (20/0.175) \times (f - 5.2)$ | – | +| | $5.375 < f < 8.325$ | –100 | –52 | +| | $8.325 \leq f \leq 8.5$ | $-80 + (20/0.175) \times (f - 8.5)$ | – | + +**Table C.7 – VTU-R Limit PSD mask (VDSL2 above POTS bands; 25-138 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|--------------------------|------------------------------------|----------------------------------------------------------| +| US2 | $8.5 < f < 12$ | $-54 + 3.5 (= -50.5)$ | – | +| | $12 \leq f \leq 12.175$ | $-80 - (20/0.175) \times (f - 12)$ | – | +| | $12.175 < f < 30$ | –100 | –52 | +| | $30 \leq f$ | –110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +**Table C.8 – VTU-R Limit PSD mask (VDSL2 above POTS band; 25-276 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|------------------------------|------------------------------------------|----------------------------------------------------------| +| US0 | $0 < f < 0.004$ | –97.5 | – | +| | $0.004 \leq f \leq 0.025875$ | $-92.5 + 20.4 \times \log_2(f/0.004)$ | – | +| | $0.025875 < f < 0.276$ | $-41 + 3.5 (= -37.5)$ | – | +| | $0.276 \leq f < 0.49341$ | $-37.5 - 72 \times \log_2(f/0.276)$ | – | +| | $0.49341 \leq f \leq 0.686$ | $-97.9 - 15 \times \log_{10}(f/0.49341)$ | – | +| | $0.686 < f < 3.575$ | –100 | – | +| | $3.575 \leq f \leq 3.75$ | $-80 + (20/0.175) \times (f - 3.75)$ | – | +| US1 | $3.75 < f < 5.2$ | $-53 + 3.5 (= -49.5)$ | – | +| | $5.2 \leq f \leq 5.375$ | $-80 - (20/0.175) \times (f - 5.2)$ | – | +| | $5.375 < f < 8.325$ | –100 | –52 | +| | $8.325 \leq f \leq 8.5$ | $-80 + (20/0.175) \times (f - 8.5)$ | – | + +**Table C.8 – VTU-R Limit PSD mask (VDSL2 above POTS band; 25-276 kHz Type(co))** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) | Maximum power limitation in a 1-MHz sliding window (dBm) | +|----------------|--------------------------|------------------------------------|----------------------------------------------------------| +| US2 | $8.5 < f < 12$ | $-54 + 3.5 (= -50.5)$ | – | +| | $12 \leq f \leq 12.175$ | $-80 - (20/0.175) \times (f - 12)$ | – | +| | $12.175 < f < 30$ | –100 | –52 | +| | $30 \leq f$ | –110 | – | + +NOTE 1 – All PSD and power measurements are in 100 $\Omega$ . +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. + +### C.2.2 VDSL2 system operating at frequencies above the TCM-ISDN DSL band + +The frequencies above 640 kHz are used for VDSL2. The frequencies below 320 kHz are used for time compression multiplexed – integrated services digital network (TCM-ISDN) DSL. The band between 320 kHz and 640 kHz is a guard band. US0 shall not be used and DS1 shall start at 640 kHz. The Limit PSD masks are defined in Tables C.9 and C.10 below. Other PSDs are for further study. + +**Table C.9 – VTU-O Limit PSD mask (VDSL2 above TCM-ISDN band)** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) (Notes 1, 2 and 4) | Maximum power limitation in a 1-MHz sliding window (dBm) (Notes 1, 3 and 4) | +|----------------|---------------------------|--------------------------------------------------|-----------------------------------------------------------------------------| +| DS1 | $0 < f < 0.12$ | –120 | | +| | $0.12 \leq f < 0.225$ | –110 | | +| | $0.225 \leq f < 0.465$ | –100 | | +| | $0.465 \leq f \leq 0.640$ | $-60 + (40/0.175) \times (f - 0.64)$ | | +| | $0.640 < f < 3.75$ | $-60 + 3.5 (= -56.5)$ | | +| | $3.75 \leq f \leq 3.925$ | $-80 - (20/0.175) \times (f - 3.75)$ | | +| | $3.925 < f < 5.025$ | –100 | –50 | +| | $5.025 \leq f \leq 5.2$ | $-80 + (20/0.175) \times (f - 5.2)$ | | +| DS2 | $5.2 < f < 8.5$ | $-60 + 3.5 (= -56.5)$ | | +| | $8.5 \leq f \leq 8.675$ | $-80 - (20/0.175) \times (f - 8.5)$ | | +| | $8.675 < f < 11.825$ | –100 | –52 | +| | $11.825 \leq f \leq 12$ | $-80 + (20/0.175) \times (f - 12)$ | | + +**Table C.9 – VTU-O Limit PSD mask (VDSL2 above TCM-ISDN band)** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) (Notes 1, 2 and 4) | Maximum power limitation in a 1-MHz sliding window (dBm) (Notes 1, 3 and 4) | +|----------------|---------------------------|--------------------------------------------------|-----------------------------------------------------------------------------| +| DS3 | $12 < f < 18.1$ | $-60 + 3.5 (= -56.5)$ | | +| | $18.1 \leq f \leq 18.275$ | $-80 - (20/0.175) \times (f - 18.1)$ | | +| | $18.275 < f < 30$ | -100 | -52 | +| | $30 \leq f$ | -110 | | + +NOTE 1 – All PSD and power measurements are into 100 $\Omega$ . +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. +NOTE 5 – The integral of the PSD does not exceed 11.0 dBm in the 30 MHz frequency range. +NOTE 6 – When SUPPORTEDCARRIERsd starts at 1 104 MHz, the Limit PSD mask below 1 104 MHz shall comply with Table F.4 of [ITU-T G.993.1]. + +**Table C.10 – VTU-R Limit PSD mask (VDSL2 above TCM-ISDN band)** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) (Notes 1, 2 and 4) | Maximum power limitation in a 1-MHz sliding window (dBm) (Notes 1, 3 and 4) | +|----------------|---------------------------|--------------------------------------------------|-----------------------------------------------------------------------------| +| US1 | $0 < f < 0.12$ | -120 | | +| | $0.12 \leq f < 0.225$ | -110 | | +| | $0.225 \leq f < 3.575$ | -100 | | +| | $3.575 \leq f \leq 3.75$ | $-80 + (20/0.175) \times (f - 3.75)$ | | +| | $3.75 < f < 5.2$ | $-60 + 3.5 (= -56.5)$ | | +| | $5.2 \leq f \leq 5.375$ | $-80 - (20/0.175) \times (f - 5.2)$ | | +| | $5.375 < f < 8.325$ | -100 | -52 | +| | $8.325 \leq f \leq 8.5$ | $-80 + (20/0.175) \times (f - 8.5)$ | | +| US2 | $8.5 < f < 12$ | $-60 + 3.5 (= -56.5)$ | | +| | $12 \leq f \leq 12.175$ | $-80 - (20/0.175) \times (f - 12)$ | | +| | $12.175 < f < 17.925$ | -100 | -52 | +| | $17.925 \leq f \leq 18.1$ | $-80 + (20/0.175) \times (f - 18.1)$ | | + +**Table C.10 – VTU-R Limit PSD mask (VDSL2 above TCM-ISDN band)** + +| Band attribute | Frequency band $f$ (MHz) | Limit PSD mask level (dBm/Hz) (Notes 1, 2 and 4) | Maximum power limitation in a 1-MHz sliding window (dBm) (Notes 1, 3 and 4) | +|----------------|--------------------------|--------------------------------------------------|-----------------------------------------------------------------------------| +| US3 | $18.1 < f < 30$ | $-60 + 3.5 (= -56.5)$ | | +| | $30 \leq f \leq 30.175$ | $-80 - (30/0.175) \times (f - 30)$ | | +| | $30.175 < f$ | $-110$ | | + +NOTE 1 – All PSD and power measurements are into 100 Ω. +NOTE 2 – The Limit PSD mask level shall be measured with a 10-kHz resolution bandwidth. +NOTE 3 – The maximum power in a 1-MHz sliding window shall be measured with a 1-MHz resolution bandwidth. +NOTE 4 – The requirements for the stopband PSD are compliant with clause 7.2.2. +NOTE 5 – The integral of the PSD does not exceed 12.3 dBm in the 30 MHz frequency range. + +**C.3 VDSL2 system with PSD reduction at frequencies below DPBOFMAX** + +The downstream transmit PSD masks for frequencies below DPBOFMAX shall not exceed RESULTMASKds( $f$ ) defined in clause 7.3.1.2.13 of [ITU-T G.997.1]. An example set of parameters intended to protect ADSL2plus is described in Appendix I. The upstream transmit PSD mask for frequencies below DPBOFMAX shall comply with Table C.3, Table C.4, Table C.7, Table C.8 or Table C.10 For frequencies between DPBOFMAX and 30 MHz, the downstream transmit PSD mask shall comply with Table C.5 or Table C.9 and the upstream transmit PSD mask shall comply with Table C.7 or Table C.10. Other PSD limitations, including US0 power reduction, are for further study. + +**C.4 Upstream power back-off (UPBO) PSD masks** + +The VTU-R shall calculate the required UPBO and its upstream PSD mask as specified in clause 7.2.1.3.2. + +The UPBO reference PSD, UPBOPSD( $f$ ), is parameterized as $-a - b \sqrt{f}$ dBm/Hz, with $f$ expressed in MHz. + +For US1 and US2 as defined in Figure C.1, values of $a$ and $b$ are given in Table C.11. These values shall apply when the Limit PSD mask for US1 and US2 does not exceed $-56.5$ dBm/Hz. + +When the Limit PSD mask for US1 and US2 is different from the one defined not to exceed $-56.5$ dBm/Hz, the values of $a$ and $b$ for UPBOPSD are for further study. For US3 defined not to exceed $-56.5$ dBm/Hz, the values of $a$ and $b$ for UPBOPSD are given in Table C.11. + +**Table C.11 – UPBOPSD parameters** + +| | | a | b | +|---------------------------------------|-----|-------------------|-------------------| +| Limit PSD mask
$\leq -56.5$ dBm/Hz | US1 | 60 | 10.2 | +| | US2 | 60 | 6.42 | +| | US3 | 40
(Note) | 0
(Note) | +| Other Limit PSD masks | US1 | For further study | For further study | +| | US2 | | | +| | US3 | | | + +NOTE – ITU-T G.997.1 defines the set of parameter values *a* = 40 dBm/Hz, *b* = 0 dBm/Hz as a special configuration to disable UPBO in the respective upstream band. + +## C.5 Service Splitter + +See F.2 of [ITU-T G.993.1]. + +For operation according to Annex C, the requirements applying over a frequency band up to 12 MHz in [ITU-T G.993.1] shall be met over a frequency band up to 30 MHz. + +However, the return loss of the POTS splitter in the band between 12 MHz and 30 MHz shall be measured as shown in Figure C.2. + +![Circuit diagram for impedance measurements of a POTS splitter. The splitter is represented by a dashed box containing a Low Pass Filter (LPF) and two 0.12 microfarad capacitors. It has three ports: 1) POTS/PSTN port on the left, connected to a 600 ohms resistor and an open circuit. 2) Line port on the right, connected to Test equipment; an arrow indicates the input impedance Zin looking into the Line port. 3) xDSL port at the bottom, connected to a 100 ohms resistor. The Test equipment is also connected to a 100 ohms return loss reference impedance. Below the diagram is the formula for return loss.](3a3550dbfeac19294da8225054d80742_img.jpg) + +$$\text{Return loss} = -20 \text{ Log} \left| \frac{100 - Z_{in}}{Z_{in} + 100} \right| \text{ dB}$$ + +G.993.2\_FC-2 + +Circuit diagram for impedance measurements of a POTS splitter. The splitter is represented by a dashed box containing a Low Pass Filter (LPF) and two 0.12 microfarad capacitors. It has three ports: 1) POTS/PSTN port on the left, connected to a 600 ohms resistor and an open circuit. 2) Line port on the right, connected to Test equipment; an arrow indicates the input impedance Zin looking into the Line port. 3) xDSL port at the bottom, connected to a 100 ohms resistor. The Test equipment is also connected to a 100 ohms return loss reference impedance. Below the diagram is the formula for return loss. + +**Figure C.2 – Impedance measurements in the band between 12 MHz and 30 MHz for the CO and remote POTS splitters** + +## C.6 Test loops and crosstalk disturbers + +### C.6.1 Test loops + +#### C.6.1.1 Loop configurations + +For frequency bands below 12 MHz, see clause F.3.1.1 of [ITU-T G.993.1]. For VDSL2 using frequency bands above 12 MHz, the following settings for bridged tap parameter *Y*2 shall be added to test loop VLOOP-J3 (see Figure F.10 of [ITU-T G.993.1]): + +*Y*2 = 1-10 m at every 1 m step. + +### **C.6.1.2 Primary line constants** + +See F.3.1.2 of [ITU-T G.993.1]. + +The equations of primary line constants are applicable up to 30 MHz. + +### **C.6.1.3 Line transfer function and test loop characteristics** + +See F.3.1.3 of [ITU-T G.993.1]. + +## **C.6.2 Crosstalk disturbers** + +### **C.6.2.1 Disturber types** + +See F.3.2.1 of [ITU-T G.993.1]. + +The five disturber types shown below using ITU-T G.992.1 (Annex I), VDSL2 self, and PNT3 ( in [ITU-T G.9954]) shall be added: + +- Noise B5 = 9 VDSL2 self NEXT and FEXT (see Tables C.1 to C.10 for the disturber PSD); +- Noise B6 = 9 ADSL NEXT and FEXT (see Figure I.13 of [ITU-T G.992.1] (I.4.8.1 of [ITU-T G.992.1]) for the disturber PSD); +- Noise B7 = 9 PNT3 (mask #1) NEXT (see Table 6-10 of [ITU-T G.9954] (mask #1) in clause 6.8.3.1 of [ITU-T G.9954] for the disturber PSD); +- Noise B8 = 9 PNT3 (mask #2) NEXT (see Table 6-12 of [ITU-T G.9954]) (mask #2) in clause 6.8.3.1 of [ITU-T G.9954] for the disturber PSD); and +- Noise B9 = 9 PNT3 (mask #3) NEXT (see Table 6-14 of [ITU-T G.9954]) (mask #3) in clause 6.8.3.1 of [ITU-T G.9954] for the disturber PSD). + +Other disturbers are for further study. + +### **C.6.2.2 Power spectral density of disturbers** + +See F.3.2.2 of [ITU-T G.993.1]. + +For Annex I of [ITU-T G.992.1], see Figure I.13 of [ITU-T G.992.1] (I.4.8.1 of [ITU-T G.992.1]). The disturber has an offset of -3.5 dB with respect to the peak mask defined in Figure I.13 of [ITU-T G.992.1]. For VDSL2 self, see Tables C.1 to C.10. In the in-band regions, the disturber has an offset of -3.5 dB with respect to the peak mask defined in Tables C.1 to C.10. For PNT3 (ITU-T G.9954), see Table 6-10 of [ITU-T G.9954] (mask #1), Table 6-12 of [ITU-T G.9954] (mask #2) and Table 6-14 of [ITU-T G.9954] (mask #3) in clause 6.8.3.1 of [ITU-T G.9954]. + +### **C.6.2.3 Power spectral density of crosstalk** + +See clause F.3.2.3 of [ITU-T G.993.1]. + +## Annex D + +### Long Reach VDSL2 + +(This annex forms an integral part of this Recommendation.) + +#### D.1 Introduction + +This annex defines the Long Reach mode for VDSL2 without vectoring. + +The Annex B of [ITU-T G.993.5] defines vectored long reach VDSL2. This annex is a delta specification to Annex B of [ITU-T G.993.5]. + +A VTU-R supporting operation according to this annex, shall also support operation according to Annex B of [ITU-T G.993.5]. + +A VTU-O supporting operation according to this annex, may also support operation according to Annex B of [ITU-T G.993.5]. + +If during the ITU-T G.994.1 handshake phase, VDSL2-LR operation is selected and operation according to [ITU-T G.993.5] is not selected, then the VTU-O and VTU-R shall operate according to this annex. + +#### D.2 Overview of the initialization procedure + +The VDSL2-LR initialization procedure includes two parts: + +- 1) Regular ITU-T G.993.2 procedure (including ITU-T G.993.2 channel estimation) with minor modifications; and +- 2) Additional stages: + - PROBING: During this stage, the VTU-R determines the length of the line and indicates to the VTU-O whether to continue the VDSL2-LR initialization in short-medium operation or in long loop operation. Following the indication from the VTU-R, both the VTU-O and the VTU-R continue the initialization of the line in short-medium loop operation or in long loop operation; + - TRAINING: This stage is present if the VTU-R selected to continue the initialization of the line in long loop operation. During this stage, the VTU-O and VTU-R train the line for long loop operation. + +The framework of the initialization procedure is presented in Figure D.1. It illustrates VDSL2-LR initialization (compared to regular ITU-T G.993.2 initialization), using the following notations for the exchanged signals: + +- ITU-T G.993.2 signals – used if the line is a regular ITU-T G.993.2 line, i.e., not operating according to this annex (a regular ITU-T G.993.2 line); +- LR signals, short-medium – used if the line is selected during the PROBING stage to continue the VDSL2-LR initialization in short-medium loop operation (to become a short or medium VDSL2-LR line); +- LR signals, long – used if the line is selected during the PROBING stage to continue the VDSL2-LR initialization in long loop operation (for a long VDSL2-LR line). + +![](f197ea730e7500c292004f2d86a584b6_img.jpg) + +| | Messages | LR signals, long | LR signals, short-medium | ITU-T G.993.2 signals | | | ITU-T G.993.2 signals | LR signals, short-medium | LR signals, long | Messages | +|----------------------------------------------|----------------|-------------------------|--------------------------|-------------------------|-------------------------------------------------------------|--|-------------------------|--------------------------|------------------|----------------| +| Regular part of ITU-T G.993.2 initialization | ITU-T G.994.1 | ITU-T G.994.1 handshake | | | | | ITU-T G.994.1 handshake | | | ITU-T G.994.1 | +| | | O-P-QUIET 1 | | | Regular ITU-T G.993.2 CD phase (regular ITU-T G.993.2 line) | | R-P-QUIET 1 | | | | +| Additional part performed in VDSL2-LR lines | O-P-MSG-PCB-LR | O-P-PROBING-LR | | O-P-CHANNEL DISCOVERY 1 | O-SIGNATURE received (regular ITU-T G.993.2 line) | | | | R-P-MSG-PCB-LR | | +| | | | | | VTU-R obtained loop timing (long LR line) | | R-P-CHANNEL DISCOVERY 1 | R-P-PROBING-LR | | | +| | | O-P-QUIET 1-LR | | | Decision short-medium vs long LR line | | | | | R-P-QUIET 1-LR | +| | | O-P-TRAINING-LR | O-P-CHANNEL DISCOVERY 1 | | Regular ITU-T G.993.2 CD phase (short-medium LR line) | | R-P-QUIET 1 | | | | +| | | | | | O-SIGNATURE received (short-medium LR line) | | R-P-CHANNEL DISCOVERY 1 | R-P-TRAINING-LR | | | +| | | | | | Regular ITU-T G.993.2 CD phase (long LR line) | | | | | | +| Regular part of ITU-T G.993.2 initialization | O-IDLE | O-P-CHANNEL DISCOVERY 1 | | | O-SIGNATURE received (long LR line) | | | | R-P-QUIET 1 | | +| | O-SIGNATURE | | | | | | R-P-CHANNEL DISCOVERY 1 | | | | + +G.993.2(15)-Amd.3(18)\_FD.1 + +**Figure D.1 – Overview of the VDSL2-LR initialization (compared to regular ITU-T G.993.2 initialization)** + +### D.3 ITU-T G.994.1 handshake phase + +See clause B.3 of [ITU-T G.993.5]. + +### D.4 Signals sent by the VTU-O during the channel discovery phase + +See clause B.4 of [ITU-T G.993.5] with the following differences: + +- The length of O-P-VECTOR 0 shall be set to zero symbols; +- The length of O-P-VECTOR 1-LR shall be set to zero symbols; +- The O-P-VECTOR 1 shall be set to zero symbols; +- The O-P-QUIET 1 signal shall be followed by the O-P-PROBING-LR signals; +- If the initialization of the line shall be continued in short-medium operation, then the O-P-QUIET 1-LR signal shall be followed by the O-P-CHANNEL DISCOVERY 1 signal (sending O-IDLE) and the remainder of the channel discovery phase shall be as defined in clause 12.3.3; +- If the initialization of the line shall be continued in long loop operation, then the O-P-QUIET 1-LR signal shall be followed by the O-P-TRAINING-LR signal; +- The IDFT size during O-P-TRAINING-LR may be a size that is different from the Initial IDFT size indicated in the ITU-T G.994.1 CL message. The IDFT size (2N) shall be at least 2048 (i.e., $n \geq 11$ ), so that there is no image above the subcarrier with index 511; + +- After O/R-P-TRAINING-LR signal exchange is complete, the line continues the regular ITU-T G.993.2 initialization. The O-P-TRAINING-LR signals shall be followed by the O-P-CHANNEL DISCOVERY 1 signal defined in clause 12.3.3.3.1.2 and the remainder of the channel discovery phase defined in clause 12.3.3; +- Clauses B.4.7 and B.4.8 of [ITU-T G.993.5] apply to the ITU-T G.993.2 channel discovery phase. + +NOTE – VDSL2-LR long lines, VDSL2-LR short-medium lines and ITU-T G.993.2 lines may not have the O-SIGNATURE message sent at the same time. + +## **D.5 Signals sent by the VTU-R during the channel discovery phase** + +See clause B.5 of [ITU-T G.993.5] with the following differences: + +- The length of R-P-QUIET 2-LR shall be set to zero symbols; +- After O/R-P-TRAINING-LR signal exchange is complete, the line continues regular ITU-T G.993.2 initialization; +- The R-P-TRAINING-LR signals shall be followed by the R-P-QUIET 1 signal defined in clause 12.3.3.3.2.1 and the remainder of the channel discovery phase defined in clause 12.3.3; +- Clause B.5.6 of [ITU-T G.993.5] applies to the ITU-T G.993.2 channel discovery phase and clause B.5.7 of [ITU-T G.993.5] applies to the ITU-T G.993.2 training phase. + +## **D.6 O/R-P-PROBING-LR signal exchange** + +See clause B.6 of [ITU-T G.993.5]. + +## **D.7 O/R-P-TRAINING-LR signal exchange** + +See clause B.7 of [ITU-T G.993.5] with the following differences: + +- The first symbol of O-P-SEGUE 1-LR is used as reference time point to facilitate alignment between timing of VDSL-LR training and the ITU-T G.993.2 channel discovery (see clause 12.3.3); +- The O-P-PILOT-LR signal shall be as defined in clause D.7.1; +- The R-P-SEGUE 1-LR state shall be followed by the ITU-T G.993.2 R-P-QUIET 1 state. + +### **D.7.1 O-P-PILOT-LR (replaces clause B.7.1.14 of ITU-T G.993.5)** + +In the O-P-PILOT-LR state, the VTU-O shall transmit an integer number of O-P-PILOT symbols. The duration of the O-P-PILOT-LR state shall be 128 symbols. + +The O-P-PILOT is a non-periodic signal. The alignment of the O-P-PILOT symbols and the O-P-SEGUE 1-LR state shall use two reference points associated with the IDFT sample #0 of specific symbols. The IDFT sample #0 is defined as the first sample of the block of 2N time samples generated by the IDFT. + +The first reference point shall be the IDFT sample #0 of the first symbol of the O-P-SEGUE 1-LR state, and the second reference point is the IDFT sample #0 of the first symbol of the O-P-PILOT-LR state, as shown in the Figure D.2. + +![Figure D.2: Reference samples for alignment of downstream symbols between the O-SEGUE 1-LR state and O-P-PILOT-LR state. The diagram shows two symbol structures. The top structure is for O-P-SEGUE1-LR (First symbol), showing a block of length 2N with a reference sample 'IDFT sample #0' at an offset of beta. The bottom structure is for O-P-PILOT-LR, showing a block of length 2N with a reference sample 'IDFT sample #0' at an offset of L_CP - beta. The total length of the O-P-PILOT-LR symbol is L_CP + 2N + L_CS, where L_CP and L_CS are cyclic prefix and suffix lengths, and beta is the guard interval length.](5083128e335a383c042e15d2d8795c95_img.jpg) + +G.993.2(15)-Amd.3(18)\_FD.2 + +Figure D.2: Reference samples for alignment of downstream symbols between the O-SEGUE 1-LR state and O-P-PILOT-LR state. The diagram shows two symbol structures. The top structure is for O-P-SEGUE1-LR (First symbol), showing a block of length 2N with a reference sample 'IDFT sample #0' at an offset of beta. The bottom structure is for O-P-PILOT-LR, showing a block of length 2N with a reference sample 'IDFT sample #0' at an offset of L\_CP - beta. The total length of the O-P-PILOT-LR symbol is L\_CP + 2N + L\_CS, where L\_CP and L\_CS are cyclic prefix and suffix lengths, and beta is the guard interval length. + +**Figure D.2 – Reference samples for alignment of downstream symbols between the O-SEGUE 1-LR state and O-P-PILOT-LR state** + +The time offset expressed in samples between those reference points modulo the period of a DMT symbol with CE, i.e., $2N+L_{CE}$ samples, shall be as indicated by the VTU-O in the ITU-T G.994.1 Spar(2) codepoint "offset IDFT sample #0" indicated by the VTU-O. The parameter "offset IDFT sample #0" shall be an integer number of samples at the rate of 4.416 MHz. + +NOTE – The value of this offset is equal to $L_{CP}-\beta$ which is always less than or equal to $L_{CE}$ , see Figure D.2. Knowledge of that offset by the receiver, allows VTU-R to derive the symbol timing during the O-P-PILOT-LR and transition into [ITU-T G.993.2] channel discovery phase with timing acquired in the VDSL2-LR TRAINING stage. This, in turn, allows to re-use TEQ settings and other transceiver settings obtained during the VDSL2-LR TRAINING stage. + +The O-P-PILOT-LR state shall be followed by the O-P-CHANNEL DISCOVERY 1 signal and the remainder of the ITU-T G.993.2 channel discovery phase with amendments as specified in clause D.8. + +## **D.8 ITU-T G.993.2 channel discovery phase and training phase in long loop operation** + +This clause contains additional requirements on the ITU-T G.993.2 channel discovery phase and training phase that apply if the long loop operation of VDSL2-LR is selected (see clauses B.4.8, B.4.9, B.5.6 and B.5.7 of [ITU-T G.993.5]). + +The setting of the transmit path between the IDFT output and the corresponding U-interface of both the VTU-R and VTU-O that was established during the TRAINING stage shall be kept unchanged during the ITU-T G.993.2 channel discovery phase and training phase. The IDFT size and type of image used during the ITU-T G.993.2 channel discovery and training phases shall be the same as those used during the TRAINING stage. + +### **D.8.1 ITU-T G.993.2 channel discovery phase in long loop operation** + +The SUPPORTEDCARRIERSDs set shall be limited to subcarrier index 511. + +The SUPPORTEDCARRIERSus set shall be limited to subcarrier index 31 for US0 type A, and to subcarrier index 63 for US0 types B and M. + +#### **D.8.1.1 Transition to ITU-T G.993.2 channel discovery phase** + +In the downstream direction, symbols in ITU-T G.993.2 channel discovery phase shall be aligned with symbols in O-P-PILOT-LR. + +In the upstream, the transition from VDSL2-LR TRAINING stage to ITU-T G.993.2 CHANNEL DISCOVERY PHASE shall be aligned using two reference points associated with the IDFT sample #0 of specific symbols. The IDFT sample #0 is defined as the first sample of the block of $2N$ time samples generated by the IDFT. + +The first reference point shall be the IDFT sample #0 of the first symbol of the R-P-SEGUE 1-LR state and the second reference point shall be the IDFT sample #0 of the first symbol of the R-P-CHANNEL DISCOVERY 1 signal, as shown in the Figure D.3. + +![Figure D.3: Reference samples for alignment of upstream symbols between the VDSL2-LR TRAINING stage and ITU-T G.993.2 channel discovery phase. The diagram shows two signal blocks. The top block is 'R-P-SEGUE1-LR (First symbol)' with a total length of 2N samples. A yellow vertical bar marks the 'IDFT sample #0' at the start of the 2N block. A horizontal double-headed arrow labeled β indicates the time offset from the start of the block to the IDFT sample #0. The bottom block is 'R-P-CHANNEL-DISCOVERY 1' with a total length of 2N samples. A yellow vertical bar marks the 'IDFT sample #0' at the start of the 2N block. A horizontal double-headed arrow labeled L_CP - β indicates the time offset from the start of the block to the IDFT sample #0. Below the bottom block, a horizontal double-headed arrow labeled β indicates the time offset from the start of the block to the IDFT sample #0. Another horizontal double-headed arrow labeled L_CP indicates the time offset from the start of the block to the IDFT sample #0. A horizontal double-headed arrow labeled 2N indicates the length of the 2N samples block. A horizontal double-headed arrow labeled L_CS indicates the time offset from the end of the 2N samples block to the start of the next block. The text 'G.993.2(19)_FD.3' is at the bottom right.](230151de787f38fa96749379eafb9f37_img.jpg) + +Figure D.3: Reference samples for alignment of upstream symbols between the VDSL2-LR TRAINING stage and ITU-T G.993.2 channel discovery phase. The diagram shows two signal blocks. The top block is 'R-P-SEGUE1-LR (First symbol)' with a total length of 2N samples. A yellow vertical bar marks the 'IDFT sample #0' at the start of the 2N block. A horizontal double-headed arrow labeled β indicates the time offset from the start of the block to the IDFT sample #0. The bottom block is 'R-P-CHANNEL-DISCOVERY 1' with a total length of 2N samples. A yellow vertical bar marks the 'IDFT sample #0' at the start of the 2N block. A horizontal double-headed arrow labeled L\_CP - β indicates the time offset from the start of the block to the IDFT sample #0. Below the bottom block, a horizontal double-headed arrow labeled β indicates the time offset from the start of the block to the IDFT sample #0. Another horizontal double-headed arrow labeled L\_CP indicates the time offset from the start of the block to the IDFT sample #0. A horizontal double-headed arrow labeled 2N indicates the length of the 2N samples block. A horizontal double-headed arrow labeled L\_CS indicates the time offset from the end of the 2N samples block to the start of the next block. The text 'G.993.2(19)\_FD.3' is at the bottom right. + +**Figure D.3 – Reference samples for alignment of upstream symbols between the VDSL2-LR TRAINING stage and ITU-T G.993.2 channel discovery phase** + +The time offset expressed in samples between those reference points modulo the period of a DMT symbol with CE, i.e., $2N+L_{CE}$ samples, shall be as indicated by the VTU-R in the ITU-T G.994.1 Spar(2) codepoint "offset IDFT sample #0". The parameter "offset IDFT sample #0" indicated by the VTU-R shall be an integer number of samples at the rate of 276 kHz. + +NOTE – The value of this offset is equal to $L_{CP}-\beta$ , which is always less than or equal to $L_{CE}$ , see Figure D.3. Knowledge of that offset by the VTU-O, allows to derive the symbol timing during the ITU-T G.993.2 channel discovery phase from the one acquired in the VDSL2-LR TRAINING stage. This, in turn, allows to re-use TEQ settings and other transceiver settings obtained during the VDSL2-LR TRAINING stage. + +#### D.8.1.2 Use of PILOT during R-P-LINEPROBE + +If the ITU-T G.993.2 R-P-LINEPROBE signal is requested, the VTU-O shall transmit O-P-PILOT 1 and transition to O-P-PERIODIC 1 640 symbols after the end of transmission of O-P-SYNCHRO 1. The O-P-PILOT 1 shall use the tone index indicated during the PROBING stage. + +#### D.8.1.3 O-SIGNATURE (amends clause 12.3.3.2.1.1 of ITU-T G.993.2) + +Field #8 "Downstream nominal maximum aggregate transmit power (MAXNOMATPds)" indicates the value of the control parameter *MAXNOMATPds*, which determines the maximum wide-band power that the VTU-O is allowed to transmit. The value of the MAXNOMATPds shall not exceed the minimum of the maximum aggregate downstream transmit power as defined in clause D.9 for the corresponding annex of [ITU-T G.993.2] and the MAXNOMATPds value configured in the CO-MIB, regardless of the particular G.993.2 profile selected during the ITU-T G.994.1 handshake phase of initialization. + +#### **D.8.1.4 PSD adjustments during ITU-T G.993.2 channel discovery phase** + +The PSD adjustments defined in ITU-T G.993.2 channel discovery phase include potential changes of the downstream highest used subcarrier and the actual downstream transmit PSD, which may result in a different downstream transmit PSD than the one defined during the PROBING stage. To avoid changes in the transmission channel and corresponding degradations in tuning of the TEQ, the mentioned adjustment of the PSD shall be done exclusively in frequency domain. + +#### **D.8.2 ITU-T G.993.2 training phase in long loop operation** + +During the transition to the ITU-T G.993.2 training phase, the VTU-R shall keep symbol timing. To keep the position of the IDFT sample #0 between the channel discovery and the training phases in upstream, the duration of R-P-QUIET 2 shall be an integer number of DMT symbols. + +#### **D.9 Definition of Limit PSD masks** + +See clause B.9 of [ITU-T G.993.5]. + +#### **D.10 Management** + +See clause B.10 of [ITU-T G.993.5]. + +#### **D.11 Nominal aggregate transmit power (NOMATP)** + +See clause B.11 of [ITU-T G.993.5]. + +### **Annex E** + +For further study. + +### **Annex F** + +For further study. + +### **Annex G** + +For further study. + +### **Annex H** + +For further study. + +## **Annex J** + +For further study. + +## **Annex K** + +For further study. + +## Annex L + +### TPS-TC functional descriptions + +(This annex forms an integral part of this Recommendation.) + +This annex contains the functional descriptions of various TPS-TC types that may be used within the ITU-T G.993.2 transceivers. + +#### L.1 STM transmission convergence (STM-TC) function + +##### L.1.1 Scope + +The STM-TC function provides procedures for the transport of one STM-TC stream in either the upstream or downstream direction. Octet boundaries and the position of most significant bits are explicitly maintained across the transport for the STM-TC stream. The STM-TC stream is presented synchronously across the $\gamma_R$ or $\gamma_O$ reference point with respect to the synchronization signals across the $\alpha/\beta$ interface. + +Support for a plesiochronous interface is under study. + +##### L.1.2 References + +This clause is intentionally blank because there are no STM-TC specific references. + +##### L.1.3 Definitions + +This clause is intentionally blank because there are no STM-TC specific definitions. + +##### L.1.4 Abbreviations + +This clause is intentionally blank because there are no STM-TC specific abbreviations. + +##### L.1.5 Transport capabilities + +The STM-TC function provides procedures for the transport of one STM-TC stream in either the upstream and downstream direction. Octet boundaries and the position of most significant bits shall be explicitly maintained across the transport for the STM-TC stream. The STM-TC stream is presented synchronously across the $\gamma_R$ or $\gamma_O$ reference point with respect to the PMD bit clocks. + +After each of the transmit STM-TC procedures has been applied, transport of the STM-TC stream to a receive STM-TC function at the other end of the link is carried out by underlying PMS-TC and PMD layers through a series of data frames and PMD symbols. The STM-TC transport capabilities are configured by control parameters described in clause L.1.7. The control parameters provide for the application of appropriate data rates and characteristics of the STM-TC stream. The values of all control parameters are set during initialization or reconfiguration of the VTU. The receive STM-TC function recovers the input signal that was presented to the corresponding transmit STM-TC function and which has been transported across the STM-TC, PMS-TC, and PMD functions of a VTU-O and VTU-R pair. + +The transmit STM-TC function accepts input signals from the data plane and control plane within the VTU. As a data plane element, the transmit STM-TC function accepts one STM-TC stream from the $\gamma_O$ or $\gamma_R$ reference points. The stream is associated with one, and only one, STM-TC function. These input signals are conveyed to the receive STM-TC interface as shown in Figure L.1. Octet boundaries and the position of most significant bits are explicitly maintained across the transport for the STM-TC frame bearers. + +![Figure L.1: STM-TC transport capabilities within the user plane. The diagram shows two parallel stacks of network functions. The left stack (VTU-R) consists of 'VTU-R higher layer STM functions', 'VTU-R STM-TCs', 'VTU-R PMS-TC', and 'VTU-R PMD'. The right stack (VTU-O) consists of 'VTU-O higher layer STM functions', 'VTU-O STM-TCs', 'VTU-O PMS-TC', and 'VTU-O PMD'. Both stacks sit on a 'Physical TP media' layer. Arrows indicate 'Upstream STM-TC streams' and 'Upstream frame bearers' entering from the left and right respectively. 'Downstream STM-TC streams' and 'Downstream frame bearers' exit to the left and right. Interface points are labeled with Greek letters: γR, γO, β, and α. A dotted line separates the 'Downstream' (top) and 'Upstream' (bottom) functions within each stack. The diagram is labeled 'NT1, NT1/2' on the left, 'LT' on the right, and 'G.993.2(15)_FL.1' at the bottom right. A 'U' is shown below the physical media.](e488c90b7f1a3c764cf9b50918f1ca6d_img.jpg) + +Figure L.1: STM-TC transport capabilities within the user plane. The diagram shows two parallel stacks of network functions. The left stack (VTU-R) consists of 'VTU-R higher layer STM functions', 'VTU-R STM-TCs', 'VTU-R PMS-TC', and 'VTU-R PMD'. The right stack (VTU-O) consists of 'VTU-O higher layer STM functions', 'VTU-O STM-TCs', 'VTU-O PMS-TC', and 'VTU-O PMD'. Both stacks sit on a 'Physical TP media' layer. Arrows indicate 'Upstream STM-TC streams' and 'Upstream frame bearers' entering from the left and right respectively. 'Downstream STM-TC streams' and 'Downstream frame bearers' exit to the left and right. Interface points are labeled with Greek letters: γR, γO, β, and α. A dotted line separates the 'Downstream' (top) and 'Upstream' (bottom) functions within each stack. The diagram is labeled 'NT1, NT1/2' on the left, 'LT' on the right, and 'G.993.2(15)\_FL.1' at the bottom right. A 'U' is shown below the physical media. + +**Figure L.1 – STM-TC transport capabilities within the user plane** + +As a management plane element, there are no specific transport functions provided by the STM-TC function. However, there are some specific indicator bits and overhead response definitions for the STM-TC function as defined in this annex. + +#### L.1.6 Interface primitives + +Each VTU-O STM-TC function has many interface signals as shown in Figure L.2. Each named signal is composed of one or more primitives, as denoted by the directional arrows. The primitive type associated with each arrow is according to the figure legend. + +The diagram is divided by a dotted line to separate the downstream function and signals from the upstream. The signals shown at the top edge convey primitives to and from the higher layer STM function. The signals shown at the bottom edge convey primitives to and from the PMS-TC function. + +Each VTU-R STM-TC function has similar interface signals as shown in Figure L.3. In this figure, the upstream and downstream labels are reversed from Figure L.1. + +![Diagram of VTU-O STM-TC function signals. It shows a 'Transmit STM-TC function' block on the left and a 'Receive STM-TC function' block on the right, both within a 'VTU-O TPS-TC function' boundary. Above the blocks is a horizontal line labeled γ₀, and below is a line labeled α. The left side is labeled 'Downstream' and the right 'Upstream'. Arrows represent primitives: red dashed for .request, blue dashed for .confirm, purple dashed for .indicate, and green dashed for .response. Labels include STM-TC. Stream(n), Frame. Bearer(n), and Frame. Synchflag.](ca3e73b333ff171a0a2cb65b1d149490_img.jpg) + +STM-TC. Stream(*n*) + +STM-TC. Stream(*n*) + +γ0 + +Transmit STM-TC function + +VTU-O TPS-TC function + +Receive STM-TC function + +α + +Frame. Bearer(*n*) + +Frame. Synchflag + +Downstream + +Upstream + +Primitives: + ■ - - -> .request + ◀ - - - ■ .confirm + ■ - - -> .indicate + ◀ - - - ■ .response + +G.993.2(15)\_FL.2 + +Diagram of VTU-O STM-TC function signals. It shows a 'Transmit STM-TC function' block on the left and a 'Receive STM-TC function' block on the right, both within a 'VTU-O TPS-TC function' boundary. Above the blocks is a horizontal line labeled γ₀, and below is a line labeled α. The left side is labeled 'Downstream' and the right 'Upstream'. Arrows represent primitives: red dashed for .request, blue dashed for .confirm, purple dashed for .indicate, and green dashed for .response. Labels include STM-TC. Stream(n), Frame. Bearer(n), and Frame. Synchflag. + +**Figure L.2 – Signals of the VTU-O STM-TC function** + +![Diagram of VTU-R STM-TC function signals. It shows a 'Transmit STM-TC function' block on the left and a 'Receive STM-TC function' block on the right, both within a 'VTU-R TPS-TC function' boundary. Above the blocks is a horizontal line labeled γᴿ, and below is a line labeled α. The left side is labeled 'Upstream' and the right 'Downstream'. Arrows represent primitives: red dashed for .request, blue dashed for .confirm, purple dashed for .indicate, and green dashed for .response. Labels include STM-TC. Stream(n), Frame. Bearer(n), and Frame. Synchflag.](9c0f8acdb03202b00f58f1c6b9567c7e_img.jpg) + +STM-TC. Stream(*n*) + +STM-TC. Stream(*n*) + +γR + +Transmit STM-TC function + +VTU-R TPS-TC function + +Receive STM-TC function + +α + +Frame. Bearer(*n*) + +Frame. Synchflag + +Upstream + +Downstream + +Primitives: + ■ - - -> .request + ◀ - - - ■ .confirm + ■ - - -> .indicate + ◀ - - - ■ .response + +G.993.2(15)\_FL.3 + +Diagram of VTU-R STM-TC function signals. It shows a 'Transmit STM-TC function' block on the left and a 'Receive STM-TC function' block on the right, both within a 'VTU-R TPS-TC function' boundary. Above the blocks is a horizontal line labeled γᴿ, and below is a line labeled α. The left side is labeled 'Upstream' and the right 'Downstream'. Arrows represent primitives: red dashed for .request, blue dashed for .confirm, purple dashed for .indicate, and green dashed for .response. Labels include STM-TC. Stream(n), Frame. Bearer(n), and Frame. Synchflag. + +**Figure L.3 – Signals of the VTU-R STM-TC function** + +The signals shown in Figures L.2 and L.3 are used to carry primitives between functions of this Recommendation. Primitives are only intended for purposes of clearly specifying functions to assure interoperability. + +The primitives that are used between a higher layer STM function and STM-TC function are described in Table L.1. These primitives support the exchange of frame bearer data and regulation of data flow to match the PMS-TC configuration. They also support coordinated on-line reconfiguration of the VTU-O and VTU-R. + +**Table L.1 – Signalling primitives between STM higher layer functions and the STM-TC function** + +| Signal | Primitive | Description | +|-------------------------------|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TPS-TC.Stream( n ).STM | .request | This primitive is used by the transmit STM-TC function to request one or more octets from the transmit higher layer STM function to be transported. By the interworking of the request and confirm, the data flow is matched to the STM-TC configuration (and underlying functions). Primitives are labelled n , where n corresponds to the TPS-TC function id (e.g., n = 0 for TPS-TC #0). | +| | .confirm | The transmit higher layer STM function passes one or more octets to the STM-TC function to be transported with this primitive. Upon reception of this primitive, the STM-TC function shall perform the data plane procedures in clause L.1.8. | +| | .indicate | The receive STM-TC function passes one or more octets that have been transported with this primitive to the receive higher layer STM function. | + +### L.1.7 Control parameters + +The configuration of the STM-TC function is controlled by a set of control parameters defined in Table L.2 in addition to those specified in the main body of this Recommendation. The values of these control parameters shall be set and communicated during initialization or reconfiguration (if applicable) of a VTU pair. All the values are determined by application requirements and means that are beyond the scope of this Recommendation. + +**Table L.2 – STM-TC parameters** + +| Parameter | Definition | +|-----------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Minimum net data rate
net_minn | The minimum net data rate supported by the STM-TC stream # n . The VTU shall implement appropriate initialization and reconfiguration procedures to provide net_minn data rate. | +| Maximum net data rate
net_maxn | The maximum net data rate supported by STM-TC stream # n . During initialization and reconfiguration procedures, the net data rate shall not exceed this value. | +| Minimum SOS net data rate
MIN-SOS-BRn | The minimum net data rate required by the STM-TC stream # n for a valid SOS request (see clause 13.4). | +| Minimum reserved data rate
net_reserven | The minimum reserved data rate supported by STM-TC stream # n that shall always be available upon request by an appropriate reconfiguration procedure. The value of net_reserven shall be constrained such that net_minn ≤ net_reserven ≤ net_maxn . This parameter is not used in this version of this Recommendation and shall be set to net_minn . The OLR procedures that utilize this parameter will be defined in a future revision of this Recommendation. | +| Maximum PMS-TC latency
delay_maxn | The STM-TC stream # n shall be transported with underlying PMS-TC functions configured such that the derived parameter delayp is no larger than this control parameter delay_maxn . | +| Minimum PMS-TC impulse noise protection
INP_minn | The STM-TC stream # n shall be transported with underlying PMS-TC functions configured such that the derived parameter INPp is not lower than this control parameter INP_minn . | + +**Table L.2 – STM-TC parameters** + +| Parameter | Definition | +|--------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Channel initialization policy $CIpolicy_n$ | This parameter controls the policy to be applied in setting the transceiver configuration parameters during initialization (see clause 12.3.7). | +| Maximum delay variation $DV\_max_n$ | The STM-TC stream #n shall be transported with underlying PMS-TC OLR function as defined in clause 13.4 such that the derived parameter $DV_p$ is not lower than this control parameter $DV\_max_n$ . | + +If the values of $net\_min_n$ , $net\_max_n$ , and $net\_reserve_n$ (see Table 12-54) are set to the same value, then the STM-TC stream is designated as a fixed data rate STM-TC stream (i.e., RA-MODE = MANUAL, see Table 12-49). If $net\_min_n = net\_reserve_n$ and $net\_min_n \neq net\_max_n$ , then the STM-TC stream is designated as a flexible data rate STM-TC stream. If the value of $net\_min_n \neq net\_max_n \neq net\_reserve_n$ , then the STM-TC stream is designated as a flexible data rate STM-TC stream with reserved data rate allocation. + +During initialization and reconfiguration procedures (except SOS), the actual net data rate $net\_act_n$ for stream #n shall always be set to the value of the derived parameter $NDR_{pn}$ of the underlying PMS-TC latency path function and shall be constrained such that $net\_min_n \leq net\_act_n \leq net\_max_n$ . However, in case the $net\_min_n = net\_max_n$ , the $net\_act_n$ may exceed the $net\_max_n$ by up to 8 kbit/s, to allow for the PMS-TC net data rate granularity (see Table 5-1). If $net\_min_n < net\_max_n$ , the $net\_max_n$ shall be set at least 8 kbit/s above the $net\_min_n$ , to allow for the PMS-TC net data rate granularity to meet the $net\_min_n \leq net\_act_n \leq net\_max_n$ requirement. The actual latency for the stream #n, $delay\_act_n$ shall always be set to the value of the derived parameter $delay_p$ of the underlying PMS-TC latency path function and constrained such that $delay\_act_n \leq delay\_max_n$ . + +The actual impulse noise protection, $INP\_act_n$ , of transport of stream #n shall always be set to the value of the derived parameter $INP_p$ of the underlying PMS-TC path function and constrained such that $INP\_act_n \geq INP\_min_n$ . The values $net\_act_n$ , $delay\_act_n$ and $INP\_act_n$ are not control parameters; these values are the result of specific initialization and reconfiguration procedures. + +During SOS reconfiguration procedures, the net data rates, INP and delay shall comply with clause 13.4. + +#### L.1.7.1 Valid configurations + +The configurations listed in Table L.3 are valid for the STM-TC function. + +**Table L.3 – Valid configuration for STM-TC function** + +| Parameter | Capability | +|------------------|-------------------------------------------------------------------------| +| $type_n$ | 1 | +| $net\_min_n$ | $net\_min_n$ may be supported for all valid framing configurations. | +| $net\_max_n$ | $net\_max_n$ may be supported for all valid framing configurations. | +| $net\_reserve_n$ | $net\_reserve_n$ may be supported for all valid framing configurations. | +| $MIN-SOS-BR_n$ | $MIN-SOS-BR_n$ may be supported for all valid framing configurations. | +| $delay\_max_n$ | All valid values of $delay\_max_n$ (see Table 12-51). | +| $INP\_min_n$ | All valid values of $INP\_min_n$ (Table 12-51). | +| $CIpolicy_n$ | 0, 1, 2 | + +### L.1.7.2 Mandatory configurations + +If implementing a STM-TC, a VTU shall support all combinations of the values of STM-TC control parameters for a STM-TC function displayed in Tables L.4 and L.5 in the downstream and upstream directions, respectively. The transmitter and receiver shall support mandatory features displayed in these tables, and in Table L.6. + +**Table L.4 – Mandatory downstream configuration for STM-TC function** + +| Parameter | Capability | +|------------------------------|--------------------------------------| +| typen | 1 | +| delay_maxn | All valid values shall be supported. | +| INP_minn | All valid values shall be supported. | +| CIpolicyn | 0 | + +**Table L.5 – Mandatory upstream configuration for STM-TC function** + +| Parameter | Capability | +|------------------------------|--------------------------------------| +| typen | 1 | +| delay_maxn | All valid values shall be supported. | +| INP_minn | All valid values shall be supported. | +| CIpolicy | 0 | + +**Table L.6 – Mandatory bidirectional configuration for STM-TC function** + +| Parameter | Capability | +|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------| +| bi_net_min | bi_net_min shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | +| bi_net_max | bi_net_max shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | +| bi_net_reserve | bi_net_reserve shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | + +### L.1.8 Data plane procedures + +Upon reception of the *Frame.Bearer.request(*n*)* primitive, the transmit STM-TC function shall signal a *TPS-TC.Stream.STM.request* to the STM higher layer function, requesting data for transport. + +Upon reception of a *TPS-TC.STM.confirm(*n*)* primitive, the receive STM-TC function #*n* shall signal a *Frame.Bearer(*n*).confirm* primitive to the PMS-TC function, providing data for transport. + +Upon reception of the *Frame.Bearer.indicate(*n*)* primitive, the receive STM-TC function #*n* shall signal a *TPS-TC.Stream.STM.indicate* to the STM higher layer function, providing data that has been transported. + +### L.1.9 Management plane procedures + +#### L.1.9.1 Surveillance primitives + +Surveillance primitives for the STM-TC function are under study. + +### L.1.9.2 Indicator bits + +The indicator bits for TPS-TC #*n* and bearer channel #*n* (*n* = 0 or 1) are defined in clause 9.5.2.2. The TIB#*n*-0, TIB#*n*-1, TIB#*n*-2 and TIB#*n*-3 shall be set to a 1 for use in Table 9-5. + +### L.1.9.3 Overhead command formats + +#### L.1.9.3.1 Inventory command + +For further study. + +#### L.1.9.3.2 Control value read command + +For further study. + +#### L.1.9.3.3 Management Counter Read command + +The TPS-TC octets in the response to the overhead Management Counter Read command corresponding to the STM-TC function are under study. The block of counter values corresponding to the STM-TC function returned in the message described in Table 11-18 shall have zero length. + +### L.1.10 Initialization procedure + +The STM-TC shall be configured during initialization as follows: + +- During the channel analysis and exchange phase (see clause 12.3.5.2.1), the VTU-O uses the O-MSG 1 SOC message (see Table 12-49) to convey its upstream and downstream TPS-TC capabilities and bearer control parameters (see Table L.2) to the VTU-R; +- During the channel analysis and exchange phase (see clause 12.3.5.2.1), the VTU-R uses the R-MSG 2 SOC message (see Table 12-60) to convey its upstream and downstream TPS-TC capabilities and bearer control parameters (see Table L.2) to the VTU-O; +- During the channel analysis and exchange phase (see clause 12.3.5.2.1.2), the VTU-O uses the O-TPS SOC message (see Table 12-53) to convey the upstream and downstream TPS-TC configuration to the VTU-R. It is based on the capabilities that were indicated in O-MSG 1 and R-MSG 2. + +### L.1.11 On-line reconfiguration + +The on-line reconfiguration of the STM-TC is outside the scope of this Recommendation. There is no specified mechanism to modify the value of the control parameters of the STM-TC function. The values of *net\_act* and *delay\_act* are automatically updated from the underlying PMS-TC latency path function. + +#### L.1.11.1 Changes to an existing stream + +Update of the *net\_act* and *delay\_act* parameters of an existing STM-TC function shall only occur at octet boundaries. The transmit STM-TC function uses the new values of the *net\_act*, and *delay\_act* to generate octets that follow the signalling of the Frame.Synchflag.confirm primitive. The receive STM-TC function procedures process octets that follow the signalling of the Frame.Synchflag.indicate primitive using the new values of these parameters. + +## L.2 ATM transmission convergence (ATM-TC) function + +### L.2.1 Scope + +The ATM-TC function provides procedures for the transport of one ATM-TC stream in either the upstream or downstream direction. Octet boundaries and the position of most significant bits are explicitly maintained across the transport for the ATM-TC stream. The ATM-TC stream is presented asynchronously across the $\gamma_R$ or $\gamma_O$ reference point with respect to the synchronization signals across the $\alpha/\beta$ interface. + +## L.2.2 References + +References applicable to this annex are included in clause 2. + +## L.2.3 Definitions + +This clause is intentionally blank because there are no ATM-TC specific definitions. + +## L.2.4 Abbreviations + +Abbreviations applicable to this annex are included in clause 4. + +## L.2.5 Transport capabilities + +The ATM-TC function provides procedures for the transport of one ATM-TC stream in either the upstream or downstream direction. Octet boundaries and the position of most significant bits shall be explicitly maintained across the transport for the ATM-TC stream. The ATM-TC stream is presented asynchronously across the $\gamma_R$ or $\gamma_O$ reference point with respect to the PMD bit clocks. + +After each of the transmit ATM-TC procedures has been applied, transport of the ATM-TC stream to a receive ATM-TC function at the other end of the link is carried out by underlying PMS-TC and PMD layers through a series of data frames and PMD symbols. The ATM-TC transport capabilities are configured by control parameters described in clause L.2.7. The control parameters provide for the application appropriate data rates and characteristics of the ATM-TC stream. The values of all control parameters are set during initialization or reconfiguration of the VTU. The receive ATM-TC function recovers the input signal that was presented to the corresponding transmit ATM-TC function and which has been transported across the ATM-TC, PMS-TC and PMD functions of an VTU-O and VTU-R pair. + +The transmit ATM-TC function accepts input signals from the data plane and control plane within the VTU. As a data plane element, the transmit ATM-TC function accepts one ATM-TC stream from the $\gamma_O$ or $\gamma_R$ reference points. The stream is associated with one, and only one, ATM-TC function. These input signals are conveyed to the receive ATM-TC interface as shown in Figure L.4. Octet boundaries and the position of most significant bits are explicitly maintained across the transport for the ATM-TC frame bearers. + +![Diagram of ATM-TC transport capabilities within the user plane showing layers and reference points for VTU-R and VTU-O.](93322b19df17919f22167a136f610b22_img.jpg) + +The diagram illustrates the transport capabilities within the user plane for ATM-TC. It is divided into two main sections: VTU-R (left) and VTU-O (right), connected by a central 'Physical TP media' block. Reference points $\gamma_R$ and $\gamma_O$ are shown at the top, and $\beta$ and $\alpha$ are shown below the ATM-TC layer. The layers from top to bottom are: 'VTU-R higher layer ATM functions' / 'VTU-O higher layer ATM functions', 'VTU-R ATM-TCs' / 'VTU-O ATM-TCs', 'VTU-R PMS-TC' / 'VTU-O PMS-TC', and 'VTU-R PMD' / 'VTU-O PMD'. Arrows indicate 'Upstream ATM-TC streams', 'Downstream STM-TC streams', 'Upstream frame bearers', and 'Downstream frame bearers'. The diagram is labeled 'NT1, NT1/2' on the left, 'LT' on the right, and 'G.993.2(15)\_FL.4' at the bottom right. A 'U' is shown at the bottom center. + +Diagram of ATM-TC transport capabilities within the user plane showing layers and reference points for VTU-R and VTU-O. + +Figure L.4 – ATM-TC transport capabilities within the user plane + +As a management plane element, there are no specific transport functions provided by the ATM-TC function. However, there are some specific indicator bit and overhead response definitions for the ATM-TC function as defined in this annex. + +### L.2.5.1 Additional functions + +In addition to transport functions, the transmit ATM-TC function also provides procedures for rate decoupling of the ATM-TC stream and the frame bearer by ATM idle cell insertion, ATM header error control generation, and scrambling, as described in clause L.2.8. + +The receive ATM-TC function reverses each of the listed procedures so that the transported information may be recovered. Additionally, the VTU receive framing function provides several supervisory indications and defect signals associated with some of these procedures (e.g., ATM cell delineation status, HEC error check failure). + +### L.2.6 Interface primitives + +Each VTU-O ATM-TC function has many interface signals as shown in Figure L.5. Each named signal is composed of one or more primitives, as denoted by the directional arrows. The primitive type associated with each arrow is according to the figure legend. + +The diagram is divided by a dotted line to separate the downstream function and signals from the upstream. The signals shown at the top edge convey primitives to and from the higher layer ATM function. The signals shown at the bottom edge convey primitives to and from the PMS-TC function. + +Each VTU-R ATM-TC function has similar interface signals as shown in Figure L.6. In this figure, the upstream and downstream labels are reversed from Figure L.5. + +![Diagram of the VTU-O ATM-TC function showing interface signals between the Transmit and Receive ATM-TC functions, the ATM-TC Stream(n), and the Frame Bearer(n) and Synchflag. The diagram is divided into Downstream and Upstream sections by a vertical dotted line. The legend defines the primitive types: .request (red dashed arrow), .confirm (blue dashed arrow), .indicate (purple dashed arrow), and .response (green dashed arrow).](8bffff22941e018add90bd8d04b6798c_img.jpg) + +The diagram illustrates the interface primitives for the VTU-O ATM-TC function. It is divided into two main sections: Downstream (left) and Upstream (right), separated by a vertical dotted line. The central component is the VTU-O TPS-TC function, which contains the Transmit ATM-TC function (left) and the Receive ATM-TC function (right). + +- Downstream (Left):** + - Between the Transmit ATM-TC function and the ATM-TC Stream(n) (top): A red dashed arrow points up (request) and a blue dashed arrow points down (confirm). + - Between the Transmit ATM-TC function and the Frame Bearer(n) (bottom): A red dashed arrow points down (request) and a blue dashed arrow points up (confirm). + - Between the Transmit ATM-TC function and the Frame Synchflag (bottom): A red dashed arrow points down (request) and a blue dashed arrow points up (confirm). +- Upstream (Right):** + - Between the Receive ATM-TC function and the ATM-TC Stream(n) (top): A purple dashed arrow points up (indicate). + - Between the Receive ATM-TC function and the Frame Bearer(n) (bottom): A purple dashed arrow points up (indicate). + - Between the Receive ATM-TC function and the Frame Synchflag (bottom): A purple dashed arrow points up (indicate). + +The diagram also shows the boundaries of the VTU-O function, marked by horizontal lines labeled $\gamma$ (top) and $\alpha$ (bottom). + +**Primitives:** + +- Red dashed arrow: .request +- Blue dashed arrow: .confirm +- Purple dashed arrow: .indicate +- Green dashed arrow: .response + +G.993.2(15)\_FL.5 + +Diagram of the VTU-O ATM-TC function showing interface signals between the Transmit and Receive ATM-TC functions, the ATM-TC Stream(n), and the Frame Bearer(n) and Synchflag. The diagram is divided into Downstream and Upstream sections by a vertical dotted line. The legend defines the primitive types: .request (red dashed arrow), .confirm (blue dashed arrow), .indicate (purple dashed arrow), and .response (green dashed arrow). + +Figure L.5 – Signals of the VTU-O ATM-TC function + +![Diagram of the VTU-R ATM-TC function showing signal flow between the Transmit and Receive ATM-TC functions and the ATM higher layer functions. The diagram is split into Upstream and Downstream sections by a dashed line labeled VTU-R TPS-TC function. On the left (Upstream), the Transmit ATM-TC function sends .request primitives (red dashed arrows) to the ATM higher layer and receives .confirm primitives (blue dashed arrows). It also receives .request primitives from the ATM higher layer and sends .confirm primitives. On the right (Downstream), the Receive ATM-TC function sends .indicate primitives (magenta dashed arrows) to the ATM higher layer and receives .response primitives (green dashed arrows). It also receives .indicate primitives from the ATM higher layer and sends .response primitives. The ATM higher layer functions are labeled ATM-TC.Stream(n) and Frame.Bearer(n) and Frame.Synchflag. The diagram also shows the relationship between the ATM-TC function and the VTU-R TPS-TC function, with labels γk and α.](7987261f8ee9bbbfb3a4bd048a86bf72_img.jpg) + +Primitives: + - - - -> .request + - - - -> .confirm + - - - -> .indicate + - - - -> .response + G.993.2(15)\_FL.6 + +Diagram of the VTU-R ATM-TC function showing signal flow between the Transmit and Receive ATM-TC functions and the ATM higher layer functions. The diagram is split into Upstream and Downstream sections by a dashed line labeled VTU-R TPS-TC function. On the left (Upstream), the Transmit ATM-TC function sends .request primitives (red dashed arrows) to the ATM higher layer and receives .confirm primitives (blue dashed arrows). It also receives .request primitives from the ATM higher layer and sends .confirm primitives. On the right (Downstream), the Receive ATM-TC function sends .indicate primitives (magenta dashed arrows) to the ATM higher layer and receives .response primitives (green dashed arrows). It also receives .indicate primitives from the ATM higher layer and sends .response primitives. The ATM higher layer functions are labeled ATM-TC.Stream(n) and Frame.Bearer(n) and Frame.Synchflag. The diagram also shows the relationship between the ATM-TC function and the VTU-R TPS-TC function, with labels γk and α. + +**Figure L.6 – Signals of the VTU-R ATM-TC function** + +The signals shown in Figures L.5 and L.6 are used to carry primitives between functions of this Recommendation. Primitives are only intended for purposes of clearly specifying functions to assure interoperability. + +The primitives that are used between a higher layer ATM function and ATM-TC function are described in Table L.7. These primitives support the exchange of stream and frame bearer data and regulation of data flow to match the PMS-TC configuration. They also support coordinated on-line reconfiguration of the VTU-O and VTU-R. + +**Table L.7 – Signalling primitives between ATM higher layer functions and the ATM-TC function** + +| Signal | Primitive | Description | +|-----------------------------------|-----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TPS-TC.Stream( n ).
ATM | .request | This primitive is used by the transmit ATM-TC function to request one or more ATM cells from the transmit higher layer ATM function to be transported. By the interworking of the request and confirm, the data flow is matched to the ATM-TC configuration (and underlying functions). Primitives are labelled n , where n corresponds to the TPS-TC function id (e.g., n = 0 for TPS-TC #0). | +| | .confirm | The transmit higher layer ATM function passes one or more ATM cells to the ATM-TC function to be transported with this primitive. Upon reception of this primitive, the ATM-TC function shall perform the procedures in L.2.8.2. | +| | .indicate | The receive ATM-TC function passes one or more ATM cells to the receive higher layer ATM function that have been transported with this primitive. | + +## L.2.7 Control parameters + +The configuration of the ATM-TC function is controlled by a set of control parameters defined in Table L.8 in addition to those specified in the main body of this Recommendation. The values of these control parameters shall be set and communicated during initialization or reconfiguration (if applicable) of a VTU pair. All the values are determined by application requirements and means that are beyond the scope of this Recommendation. + +**Table L.8 – ATM-TC parameters** + +| Parameter | Definition | +|-----------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Minimum net data rate
net_minn | The minimum net data rate supported by the ATM-TC stream # n . The VTU shall implement appropriate initialization and reconfiguration procedures to provide net_minn data rate. | +| Maximum net data rate
net_maxn | The maximum net data rate supported by ATM-TC stream # n . During activation and reconfiguration procedures, the net data rate shall not exceed this value. | +| Minimum SOS net data rate
MIN-SOS-BRn | The minimum net data rate required by the ATM-TC stream # n for a valid SOS request (see clause 13.4). | +| Minimum reserved data rate
net_reserven | The minimum reserved data rate supported by ATM-TC stream # n that shall always be available upon request by an appropriate reconfiguration procedure. The value of net_reserven shall be constrained such that $net\_min\_n \leq net\_reserve\_n \leq net\_max\_n$ . This parameter is not used in this version of this Recommendation and shall be set to net_minn . The OLR procedures that utilize this parameter will be defined in a future revision of this Recommendation. | +| Maximum PMS-TC latency
delay_maxn | The ATM-TC stream # n shall be transported with underlying PMS-TC functions configured such that the derived parameter delayp is no larger than this control parameter delay_maxn . | +| Minimum PMS-TC impulse noise protection
INP_minn | The ATM-TC stream # n shall be transported with underlying PMS-TC functions configured such that the derived parameter INPp is not lower than this control parameter INP_minn . | +| Channel initialization policy
CIpolicyn | This parameter controls the policy to be applied in setting the transceiver configuration parameters during initialization (see clause 12.3.7). | +| Maximum delay variation
DV_maxn | The ATM-TC stream # n shall be transported with underlying PMS-TC OLR function as defined in clause 13.4 such that the derived parameter DVp is not lower than this control parameter DV_maxn . | + +If the values of *net\_minn*, *net\_maxn*, and *net\_reserven* (see Table 12-54) are set to the same value, then the ATM-TC stream is designated as a fixed data rate ATM-TC stream (i.e., RA-MODE = MANUAL, see Table 12-49). If *net\_minn* = *net\_reserven* and *net\_minn* ≠ *net\_maxn*, then the ATM-TC stream is designated as a flexible data rate ATM-TC stream. If the value of *net\_minn* ≠ *net\_maxn* ≠ *net\_reserven*, then the ATM-TC stream is designated as a flexible data rate ATM-TC stream with reserved data rate allocation. + +During initialization and reconfiguration procedures (except SOS), the actual net data rate *net\_actn* for stream #*n* shall always be set to the value of the derived parameter *NDRp* of the underlying PMS-TC latency path function and shall be constrained such that $net\_min\_n \leq net\_act\_n \leq net\_max\_n$ . However, in case the *net\_minn* = *net\_maxn*, the *net\_actn* may exceed the *net\_maxn* by up to 8 kbit/s, to allow for the PMS-TC net data rate granularity (see Table 5-1). If *net\_minn* < *net\_maxn*, the *net\_maxn* shall be set at least 8 kbit/s above the *net\_minn*, to allow for the PMS-TC net data rate granularity to meet the $net\_min\_n \leq net\_act\_n \leq net\_max\_n$ requirement. The actual latency *delay\_actn* of transport of stream #*n* shall always be set to the value of the derived parameter *delayp* of the underlying PMS-TC path function and constrained such that $delay\_min\_n \leq delay\_act\_n \leq delay\_max\_n$ . The values *net\_actn* and *delay\_actn* are not control parameters; these values are the result of specific initialization and reconfiguration procedures. + +If ATM bonding is not set in the ITU-T G.994.1 bonding code tree, $delay\_min_n$ shall be set to ZERO both upstream and downstream, and $delay\_max_n$ can be set to any valid value. If ATM bonding is set, then the ITU-T G.994.1 bonding code tree includes the value of the $max\_delay\_variation$ control parameter for downstream ATM bonding and the $delay\_min_n$ shall be set to $delay\_max_n - max\_delay\_variation$ for the downstream direction. If information related to $delay\_min_n$ is available through the VTU-R bonding management interface over the $\gamma_R$ reference point, it may take precedence over the value derived from the ITU-T G.994.1 bonding code tree. For the upstream direction, the information related to $delay\_min_n$ is available through the VTU-O bonding management interface over the $\gamma_O$ reference point. For both upstream and downstream, if $delay\_min_n$ is greater than 0, there are combinations of $delay\_min_n$ and $delay\_max_n$ that may result in a failure to connect. + +The actual impulse noise protection of the stream # $n$ , $INP\_act_n$ of transport of stream # $n$ , shall always be set to the value of the derived parameter $INP_p$ of the underlying PMS-TC path function and constrained such that $INP\_act_n \geq INP\_min_n$ . The values $net\_act_n$ , $delay\_act_n$ and $INP\_act_n$ are not control parameters; these values are the result of specific initialization and reconfiguration procedures. + +During SOS reconfiguration procedures, the net data rates, INP and delay shall comply with clause 13.4. + +#### L.2.7.1 Valid configurations + +The configurations listed in Table L.9 are valid for the ATM-TC function. + +**Table L.9 – Valid configuration for ATM-TC function** + +| Parameter | Capability | +|------------------|-------------------------------------------------------------------------| +| $type_n$ | 2 | +| $net\_min_n$ | $net\_min_n$ may be supported for all valid framing configurations. | +| $net\_max_n$ | $net\_max_n$ may be supported for all valid framing configurations. | +| $net\_reserve_n$ | $net\_reserve_n$ may be supported for all valid framing configurations. | +| $MIN-SOS-BR_n$ | $MIN-SOS-BR_n$ may be supported for all valid framing configurations. | +| $delay\_max_n$ | All valid values of $delay\_max_n$ (see Table 12-51). | +| $INP\_min_n$ | All valid values of $INP\_min_n$ (see Table 12-51). | +| $Clpolicy_n$ | 0, 1, 2 | + +#### L.2.7.2 Mandatory configurations + +If implementing an ATM-TC, a VTU shall support all combinations of the values of ATM-TC control parameters for ATM-TC function #0 displayed in Tables L.10 and L.11 in the downstream and upstream directions, respectively. The transmitter and receiver shall support mandatory features displayed in these tables, and in Table L.12. + +**Table L.10 – Mandatory downstream configuration for ATM-TC function #0** + +| Parameter | Capability | +|----------------|--------------------------------------| +| $type_n$ | 2 | +| $delay\_max_n$ | All valid values shall be supported. | +| $INP\_min_n$ | All valid values shall be supported. | +| $Clpolicy_n$ | 0 | + +**Table L.11 – Mandatory upstream configuration for ATM-TC function #0** + +| Parameter | Capability | +|------------------------------|--------------------------------------| +| typen | 2 | +| delay_maxn | All valid values shall be supported. | +| INP_minn | All valid values shall be supported. | + +**Table L.12 – Mandatory bidirectional configuration for ATM-TC function** + +| Parameter | Capability | +|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------| +| bi_net_min | bi_net_min shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | +| bi_net_max | bi_net_max shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | +| bi_net_reserve | bi_net_reserve shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | + +## L.2.8 Data plane procedures + +### L.2.8.1 Block diagram + +Figure L.7 shows the functions within a transmit ATM-TC function that supports one unidirectional ATM-TC stream and one frame bearer. The incoming ATM-TC stream is shown at the leftmost edge of Figure L.7. The output signal from the ATM-TC function forms a frame bearer (i.e., input to the transmit PMS-TC function), and is shown at the rightmost edge of Figure L.7. + +![Block diagram of transmit ATM-TC function. The diagram shows a flow from left to right: 'ATM stream #n' enters a box labeled 'ATM TC Sub-function 0'. Inside this box, the signal passes through three sub-blocks: 'ATM idle cell insertion', 'HEC generation', and 'Scrambling'. An input labeled 'net_actual_n' points to the 'ATM idle cell insertion' block. The output of the 'Scrambling' block is labeled 'Frame bearer #n'.](177c3fcd966ce11a786c0c5804dbc17b_img.jpg) + +``` + +graph LR + subgraph "ATM TC Sub-function 0" + A[ATM idle cell insertion] --> B[HEC generation] + B --> C[Scrambling] + D[net_actual_n] --> A + end + E[ATM stream #n] --> A + C --> F[Frame bearer #n] + +``` + +Block diagram of transmit ATM-TC function. The diagram shows a flow from left to right: 'ATM stream #n' enters a box labeled 'ATM TC Sub-function 0'. Inside this box, the signal passes through three sub-blocks: 'ATM idle cell insertion', 'HEC generation', and 'Scrambling'. An input labeled 'net\_actual\_n' points to the 'ATM idle cell insertion' block. The output of the 'Scrambling' block is labeled 'Frame bearer #n'. + +G.993.2(15)\_FL.7 + +**Figure L.7 – Block diagram of transmit ATM-TC function** + +In the ATM-TC stream and within the ATM-TC function, data octets shall be transmitted MSB first in accordance with [ITU-T I.361] and [ITU-T I.432.1]. All serial procedures within the ATM-TC function shall begin MSB first. Below the $\alpha$ and $\beta$ interfaces of the VTU (starting with the Frame.Bearer primitives), data octets shall be transported LSB first. As a result, the MSB of the first octet of the first ATM-TC.Stream(*n*).confirm primitive will be the LSB of the first octet of the first Frame.Bearer(*n*).confirm primitive. The labelling of bits within the ATM-TC layer and at the frame bearer is shown in Figure L.8. + +![Figure L.8: Bit mapping of the user plane transport function of the ATM-TC function. The diagram shows two rows of octets. The top row, labeled 'Octet format in ATM-TC.Stream(n).confirm primitives and within ATM-TC layer', contains octets A0 to A7. The bottom row, labeled 'Octet format in frame.bearer(n) primitives', contains octets D7 to D0. Vertical arrows connect each octet in the top row to its corresponding octet in the bottom row. The top row is labeled with LSB at A0 and MSB at A7. The bottom row is labeled with MSB at D7 and LSB at D0. A dashed horizontal line between the two rows is labeled 'α/β interface'. The reference 'G.993.2 (15)_FL.8' is in the bottom right.](ffd430265e73d833a0aa30a5dd8261e3_img.jpg) + +Figure L.8: Bit mapping of the user plane transport function of the ATM-TC function. The diagram shows two rows of octets. The top row, labeled 'Octet format in ATM-TC.Stream(n).confirm primitives and within ATM-TC layer', contains octets A0 to A7. The bottom row, labeled 'Octet format in frame.bearer(n) primitives', contains octets D7 to D0. Vertical arrows connect each octet in the top row to its corresponding octet in the bottom row. The top row is labeled with LSB at A0 and MSB at A7. The bottom row is labeled with MSB at D7 and LSB at D0. A dashed horizontal line between the two rows is labeled 'α/β interface'. The reference 'G.993.2 (15)\_FL.8' is in the bottom right. + +**Figure L.8 – Bit mapping of the user plane transport function of the ATM-TC function** + +### L.2.8.2 Rate matching by idle cell insertion + +ATM idle cells shall be inserted by the transmit function to provide ATM cell rate decoupling. ATM idle cells shall not be delivered to higher layer functions by the receive ATM-TC functions. + +ATM idle cells are identified by the standardized pattern for the cell header given in [ITU-T I.432.1]. + +### L.2.8.3 HEC octet + +The transmit ATM-TC function shall generate an HEC octet as described in [ITU-T I.432.1], including the recommended modulo 2 addition (XOR) of the binary pattern 01010101 to the HEC bits. + +The HEC covers the entire cell header. The generator polynomial coefficient set used and the HEC sequence generation procedure shall be in accordance with [ITU-T I.432.1]. + +### L.2.8.4 Cell delineation + +The receiver ATM-TC function shall perform cell delineation. The cell delineation procedure permits the identification of ATM cell boundaries in the Frame.Bearer.indicate primitives. The procedure uses the HEC field in the cell header. Cell delineation shall be performed using a coding law by checking the HEC field in the cell header according to the algorithm described in [ITU-T I.432.1]. The cell delineation procedure is shown as a state machine in Figure L.9. Each state is described in Table L.13. + +![Figure L.9: Cell delineation procedure state machine. The diagram shows three states: HUNT, PRESYNC, and SYNC. HUNT is labeled 'Bit-by-bit' and PRESYNC is labeled 'Cell-by-cell'. Transitions are: HUNT to PRESYNC on 'Correct HEC'; PRESYNC to HUNT on 'Incorrect HEC'; PRESYNC to SYNC on 'DELTA consecutive correct HEC'; SYNC to HUNT on 'ALPHA consecutive incorrect HEC'. The reference 'G.993.2 (15)_FL.9' is in the bottom right.](05cfa2b0395f40b590f1d8d7bba06cb2_img.jpg) + +Figure L.9: Cell delineation procedure state machine. The diagram shows three states: HUNT, PRESYNC, and SYNC. HUNT is labeled 'Bit-by-bit' and PRESYNC is labeled 'Cell-by-cell'. Transitions are: HUNT to PRESYNC on 'Correct HEC'; PRESYNC to HUNT on 'Incorrect HEC'; PRESYNC to SYNC on 'DELTA consecutive correct HEC'; SYNC to HUNT on 'ALPHA consecutive incorrect HEC'. The reference 'G.993.2 (15)\_FL.9' is in the bottom right. + +**Figure L.9 – Cell delineation procedure state machine** + +**Table L.13 – ATM cell delineation procedure states** + +| State | Definition | +|---------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| HUNT | In the HUNT state, the cell delineation procedure may either be performed by checking bit-by-bit or octet-by-octet for the correct HEC. Once such an agreement is found, it is assumed that one header has been found, and the procedure enters the PRESYNC state. When octet boundaries are available, the cell delineation procedure may be performed octet-by-octet. | +| PRESYNC | In the PRESYNC state, the cell delineation procedure shall be performed by checking cell-by-cell for the correct HEC. If the correct HEC has been confirmed DELTA times consecutively, the procedure enters the SYNC state. If an incorrect HEC is found, the procedure returns to the HUNT state. | +| SYNC | In the SYNC state the cell delineation procedure shall return to the HUNT state if an incorrect HEC is obtained ALPHA times consecutively. | + +Specific values of ALPHA and DELTA are vendor discretionary, because the choice of these values is not considered to affect interoperability. + +NOTE – The use of the values suggested in [ITU-T I.432.1] (ALPHA = 7, DELTA = 6) may be inappropriate due to the VTU transport characteristics. + +#### L.2.8.5 ATM cell error detection + +The receiver ATM-TC function shall implement error detection over the entire cell header as defined in [ITU-T I.432.1]. The code specified in [ITU-T I.432.1] is capable of single bit error correction and multiple bit error detection. However, HEC error correction shall not be implemented by the VTU, and any HEC error shall be considered as a multiple bit error. + +ATM cells detected to be in error shall not be passed in a TPS-TC.Stream(*n*).ATM.indicate primitive. + +#### L.2.8.6 Scrambler + +The transmit ATM-TC function shall scramble the cell payload field to improve the security and robustness of the cell delineation mechanism. The self-synchronizing scrambler uses the polynomial $X^{43} + 1$ . The scrambler procedures defined in [ITU-T I.432.1] shall be implemented. + +### L.2.9 Management plane procedures + +#### L.2.9.1 Surveillance primitives + +The ATM-TC function surveillance primitives are ATM path related. Both anomalies and defects are defined for each receiver ATM-TC function. + +Three near-end anomalies are defined as follows: + +- 1) No Cell Delineation (*ncd-n*) anomaly: An *ncd-n* anomaly occurs immediately after receiving the first Frame.Bearer(*n*).indicate primitive. The anomaly terminates when the cell delineation process of the receive ATM-TC function #*n* transitions to the SYNC state. Once cell delineation is acquired, subsequent losses of cell delineation shall be considered as *ocd-n* anomalies; +- 2) Out of Cell Delineation (*ocd-n*) anomaly: An *ocd-n* anomaly occurs when the cell delineation process of receive ATM-TC subfunction #*n* transitions from the SYNC state to the HUNT state. An *ocd-n* anomaly terminates when the cell delineation process transitions from PRESYNC state to SYNC state or when the *lcd-n* is asserted; +- 3) Header Error Check (*hec-n*) anomaly: A *hec-n* anomaly occurs each time the ATM cell header process of receiver ATM-TC function #*n* detects an error. + +These near-end anomalies are counted locally per [ITU-T G.997.1]. The values of the counter may be read or reset via local commands not defined in this Recommendation. + +Three far-end anomalies are defined as follows: + +- 1) Far-end No Cell Delineation (*fncd-n*) anomaly: An *fncd-n* anomaly is an *ncd-n* anomaly detected at the far end; +- 2) Far-end Out of Cell Delineation (*focd-n*) anomaly: An *focd-n* anomaly is an *ocd-n* anomaly detected at the far end; +- 3) Far-end Header Error Check (*fhec-n*) anomaly: An *fhec-n* anomaly is a *hec-n* anomaly detected at the far end. + +These far-end anomalies are not individually observable. The count of these far-end anomalies may be read and reset via overhead commands defined in clause 11.2.3.7. The format of the counters shall be as described in clause L.2.9.3.3. + +One near-end defect is defined as follows: + +- 1) Loss of cell delineation (*lcd-n*): This defect occurs when at least one *ocd-n* anomaly is present in each of four consecutive overhead frames and no *sef-n* is present. An *lcd-n* terminates when no *ocd-n* anomaly is present in four consecutive overhead frames. + +This near-end defect is processed locally per [ITU-T G.997.1]. + +One far-end defect is defined as follows: + +- 1) Far-end loss of cell delineation (*flcd-n*): This defect is an *lcd-n* detected at the far end. + +This far-end defect is directly observed through an indicator bit as described in clause L.2.9.2. + +#### **L.2.9.2 Indicator bits** + +The indicator bits for TPS-TC #*n* and bearer channel #*n* (*n* = 0 or 1) are defined in clause 9.5.2.2. + +The (logical OR of the) near-end defect *lcd-n* and the near-end anomalies *ncd-n* and *ocd-n* shall be mapped to the TPS-TC indicator TIB#*n*-0 and transported as described in Table 9-5. The bit shall be encoded as a 1 when inactive for use in Table 9-5. + +The TIB#*n*-1, TIB#*n*-2 and TIB#*n*-3 shall be set to a 1 for use in Table 9-5. + +NOTE – The TIB#*n*-0 corresponds to the NCD indicator bit defined in [ITU-T G.992.1]. + +#### **L.2.9.3 Overhead command formats** + +##### **L.2.9.3.1 Inventory command** + +For further study. + +##### **L.2.9.3.2 Control Value Read command** + +For further study. + +##### **L.2.9.3.3 Management Counter Read command** + +The TPS-TC management counters in the response to the overhead Management Counter Read command corresponding to the ATM-TC function shall be provided as defined in [ITU-T G.997.1]. The block of counter values corresponding to the ATM-TC function returned in the message described in Table 11-17 shall be as described in Table L.14. + +**Table L.14 – ATM-TC VTU management counter values** + +| Length (Octets) | Octet number | Content | +|-----------------|--------------|----------------------------------------------------------------| +| 4 | 1 to 4 | Counter of the HEC anomalies | +| 4 | 5 to 8 | Counter of total cells passed through HEC function | +| 4 | 9 to 12 | Counter of total cells passed to the upper layer ATM function | +| 4 | 13 to 16 | Counter of total bit errors detected in ATM idle cells payload | + +## L.2.10 Initialization procedure + +The ATM-TC shall be configured during initialization using the same procedure described in clause L.1.10. + +## L.2.11 On-line reconfiguration + +The on-line reconfiguration of the ATM-TC is outside the scope of this Recommendation. There is no specified mechanism to modify the value of the control parameters of the ATM-TC function. The value of *net\_act* and *delay\_act* are automatically updated from the underlying PMS-TC latency path function. + +### L.2.11.1 Changes to an existing stream + +Update of the *net\_act* and *delay\_act* parameters of an existing ATM-TC function shall only occur at octet boundaries. The transmit ATM-TC function uses the new values of the *net\_act*, and *delay\_act* to generate octets that follow the signalling of the Frame.Synchflag.confirm primitive. The receive ATM-TC function procedures process octets that follow the signalling of the Frame.Synchflag.indicate primitive using the new values of these parameters. + +## L.3 Packet transmission convergence function (PTM-TC) + +### L.3.1 Scope + +The PTM-TC is intended for Ethernet transport and generic packet transport. The PTM-TC function provides procedures for the transport of one PTM-TC stream in either the upstream or downstream direction. Packet boundaries, octet boundaries, and the position of most significant bits are explicitly maintained across the transport for the PTM-TC stream. The PTM-TC stream is presented asynchronously across the $\gamma_R$ or $\gamma_O$ reference point with respect to the synchronization signals across the $\alpha/\beta$ interface. + +The reference model, functionality, and $\gamma$ interface of the PMS-TC are defined in Annex N of [ITU-T G.992.3]. Referring to the reference model of Annex N of [ITU-T G.992.3], the PTM-TC function of VDSL2 could be established over either of the enabled bearer channels. + +### L.3.2 References + +References applicable to this annex are included in clause 2. + +### L.3.3 Definitions + +This clause is intentionally blank because there are no PTM-TC specific definitions. + +### L.3.4 Abbreviations + +Abbreviations applicable to this annex are included in clause 4. + +### L.3.5 Transport capabilities + +The net data rate for each PTM-TC function, both upstream and downstream, may be set independently of each other, and to any eligible value that is less than or equal to the assigned maximum net data rate in the corresponding direction. The maximum net data rate for each PTM-TC function, both upstream and downstream, is set during the system configuration. + +A PTM-TC function may be mapped to either enabled bearer channel, which in turn may or may not be interleaved. + +The PTM-TC shall provide full transparent data transfer between $\gamma_O$ and $\gamma_R$ interfaces (except non-correctable errors in the PMD sublayer due to the noise in the loop). The PTM-TC shall provide packet integrity over the bearer channel that it is mapped to. + +The PTM-TC transport capabilities are configured by control parameters described in clause L.3.7. The control parameters provide for the application appropriate data rates and characteristics of the PTM-TC stream. The values of all control parameters are set during initialization or reconfiguration of the VTU. + +The transmit PTM-TC function accepts input signals from the data plane within the VTU. As a data plane element, the transmit PTM-TC function accepts one PTM-TC stream from a PTM entity across the $\gamma_O$ or $\gamma_R$ reference point. The stream is associated with one and only one PTM-TC function. (See Figure L.10.) + +![Diagram of PTM-TC transport capabilities within the user plane showing data flow between VTU-R and VTU-O components.](c9c01edf10d99b92805bbcf277ec78b2_img.jpg) + +The diagram illustrates the transport capabilities within the user plane, showing data flow between two User Terminal (UT) components, VTU-R and VTU-O, connected via a Physical TP media. The diagram is divided into two main sections: Upstream (left) and Downstream (right). + +- Upstream (Left):** Data flows from the VTU-R higher layer packet functions down through the VTU-R PTM-TCs, then through the VTU-R PMS-TC, and finally through the VTU-R PMD to the Physical TP media. The interfaces are labeled $\gamma_R$ (between higher layers and PTM-TCs), $\beta$ (between PTM-TCs and PMS-TC), and $\alpha$ (between PMS-TC and PMD). The labels "Upstream PTM-TC streams" and "Upstream frame bearers" are present. +- Downstream (Right):** Data flows from the Physical TP media up through the VTU-O PMD, then through the VTU-O PMS-TC, then through the VTU-O PTM-TCs, and finally to the VTU-O higher layer packet functions. The interfaces are labeled $\alpha$ (between PMD and PMS-TC), $\beta$ (between PMS-TC and PTM-TC), and $\gamma_O$ (between PTM-TCs and higher layers). The labels "Downstream TPS-TC streams" and "Downstream frame bearers" are present. +- Physical TP media:** The central horizontal bar representing the physical transmission medium. It is connected to the VTU-R PMD and VTU-O PMD. The labels "NT1, NT1/2" and "LT" are at the bottom, and "U" is at the bottom center. + +Diagram of PTM-TC transport capabilities within the user plane showing data flow between VTU-R and VTU-O components. + +Figure L.10 – PTM-TC transport capabilities within the user plane + +### L.3.6 Interface primitives + +The interface signals between the PTM-TC and PMS-TC ( $\gamma$ interface) are described in Annex N of [ITU-T G.992.3]. + +### L.3.7 Control parameters + +The configuration of the PTM-TC function is controlled by a set of control parameters defined in Table L.15 in addition to those specified in the main body of this Recommendation. The values of these control parameters shall be set and communicated during initialization or reconfiguration (if applicable) of a VTU pair. All the values are determined by application requirements and means that are beyond the scope of this Recommendation. + +**Table L.15 – PTM-TC parameters** + +| Parameter | Definition | +|-----------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Minimum net data rate
net_minn | The minimum net data rate supported by the PTM-TC stream # n . The VTU shall implement appropriate initialization and reconfiguration procedures to provide net_minn data rate. | +| Maximum net data rate
net_maxn | The maximum net data rate supported by PTM-TC stream # n . During initialization and reconfiguration procedures, the net data rate shall not exceed this value. | +| Minimum SOS net data rate
MIN-SOS-BRn | The minimum net data rate required by the PTM-TC stream # n for a valid SOS request (see clause 13.4). | +| Minimum reserved data rate
net_reserven | The minimum reserved data rate supported by PTM-TC stream # n that shall always be available upon request by an appropriate reconfiguration procedure. The value of net_reserven shall be constrained such that net_minn ≤ net_reserven ≤ net_maxn . This parameter is not used in this version of this Recommendation and shall be set to net_minn . The OLR procedures that utilize this parameter will be defined in a future revision of this Recommendation. | +| Maximum PMS-TC latency
delay_maxn | The PTM-TC stream # n shall be transported with underlying PMS-TC functions configured such that the derived parameter delayp is no larger than this control parameter delay_maxn . | +| Minimum PMS-TC impulse noise protection
INP_minn | The PTM-TC stream # n shall be transported with underlying PMS-TC functions configured such that the derived parameter INPp is not lower than this control parameter INP_minn . | +| Channel initialization policy
CIpolicyn | This parameter controls the policy to be applied in setting the transceiver configuration parameters during initialization (see clause 12.3.7). | +| Maximum delay variation
DV_maxn | The PTM-TC stream # n shall be transported with underlying PMS-TC OLR function as defined in clause 13.4 such that the derived parameter DVp is not lower than this control parameter DV_maxn . | + +If the values of *net\_minn*, *net\_maxn*, and *net\_reserven* (see Table 12-54) are set to the same value, then the PTM-TC stream is designated as a fixed data rate PTM-TC stream (i.e., RA-MODE = MANUAL, see Table 12-49). If *net\_minn* = *net\_reserven* and *net\_minn* ≠ *net\_maxn*, then the PTM-TC stream is designated as a flexible data rate PTM-TC stream. If the value of *net\_minn* ≠ *net\_maxn* ≠ *net\_reserven*, then the PTM-TC stream is designated as a flexible data rate PTM-TC stream with reserved data rate allocation. + +During initialization and reconfiguration procedures (except SOS), the actual net data rate *net\_actn* for stream #*n* shall always be set to the value of the derived parameter *NDRpn* of the underlying PMS-TC latency path function and shall be constrained such that *net\_minn* ≤ *net\_actn* ≤ *net\_maxn*. However, in case the *net\_minn* = *net\_maxn*, the *net\_actn* may exceed the *net\_maxn* by up to 8 kbit/s, to allow for the PMS-TC net data rate granularity (see Table 5-1). If *net\_minn* < *net\_maxn*, the *net\_maxn* shall be set at least 8 kbit/s above the *net\_minn*, to allow for the PMS-TC net data rate granularity to meet the *net\_minn* ≤ *net\_actn* ≤ *net\_maxn* requirement. The actual latency *delay\_actn* of transport of stream #*n* shall always be set to the value of the derived parameter *delayp* of the underlying PMS-TC latency path function and constrained such that *delay\_actn* ≤ *delay\_maxn*. + +The actual impulse noise protection *INP\_actn* of transport of stream #*n* shall always be set to the value of the derived parameter *INPp* of the underlying PMS-TC path function and constrained such that *INP\_actn* ≥ *INP\_minn*. The values *net\_actn*, *delay\_actn* and *INP\_actn* are not control parameters; these values are the result of specific initialization and reconfiguration procedures. + +During SOS reconfiguration procedures, the net data rates, INP and delay shall comply with clause 13.4. + +### L.3.7.1 Valid configuration + +The configurations listed in Table L.16 are valid for the PTM-TC function. + +**Table L.16 – Valid configuration for PTM-TC function** + +| Parameter | Capability | +|--------------------------------|---------------------------------------------------------------------------------------| +| typen | 3 | +| net_minn | net_minn may be supported for all valid framing configurations. | +| net_maxn | net_maxn may be supported for all valid framing configurations. | +| net_reserven | net_reserven may be supported for all valid framing configurations. | +| MIN-SOS-BRn | MIN-SOS-BRn may be supported for all valid framing configurations. | +| delay_maxn | All valid values of delay_maxn (see Table 12-51). | +| INP_minn | All valid values of INP_minn (see Table 12-51). | +| CIpolicyn | 0, 1, 2 | + +### L.3.7.2 Mandatory configurations + +If implementing a PTM-TC function, a VTU shall support all combinations of the values of PTM-TC control parameters for PTM-TC function #0 displayed in Tables L.17 and L.18 in the downstream and upstream directions, respectively. The transmitter and receiver shall support mandatory features displayed in these tables and in Table L.19. + +**Table L.17 – Mandatory downstream configuration for PTM-TC function #0** + +| Parameter | Capability | +|------------------------------|--------------------------------------| +| typen | 3 | +| delay_maxn | All valid values shall be supported. | +| INP_minn | All valid values shall be supported. | +| CIpolicyn | 0 | + +**Table L.18 – Mandatory upstream configuration for PTM-TC function #0** + +| Parameter | Capability | +|------------------------------|--------------------------------------| +| typen | 3 | +| delay_maxn | All valid values shall be supported. | +| INP_minn | All valid values shall be supported. | + +**Table L.19 – Mandatory bidirectional configuration for PTM-TC function** + +| Parameter | Capability | +|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------| +| bi_net_min | bi_net_min shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | +| bi_net_max | bi_net_max shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | +| bi_net_reserve | bi_net_reserve shall be supported for all valid framing configurations up to and equal to the MBDC defined in clause 6.2.7 for the applicable profile. | + +### L.3.8 Functionality + +The functionality of the PTM-TC shall implement 64/65-octet encapsulation as defined in Annex N of [ITU-T G.992.3], and shall include encapsulation, packet error monitoring, data rate decoupling, and frame delineation. + +For frame error monitoring, the transmitting PTM-TC shall insert the 16-bit CRC defined in clause N.3.3 of [ITU-T G.992.3]. + +### L.3.9 Management plane procedures + +#### L.3.9.1 Surveillance primitives + +See clause N.4 of [ITU-T G.992.3]. + +#### L.3.9.2 Indicator bits + +The indicator bits for TPS-TC #*n* and bearer channel #*n* (*n* = 0 or 1) are defined in clause 9.5.2.2. The TIB#*n*-0, TIB#*n*-1, TIB#*n*-2 and TIB#*n*-3 shall be set to a 1 for use in Table 9-5. + +#### L.3.9.3 Overhead command formats + +##### L.3.9.3.1 Inventory command + +For further study. + +##### L.3.9.3.2 Control Value Read command + +For further study. + +##### L.3.9.3.3 Management Counter Read command + +The TPS-TC octets in the response to the overhead Management Counter Read command corresponding to the PTM-TC function are under study. The block of counter values corresponding to the PTM-TC function returned in the message described in Table 11-18 shall have zero length. + +### L.3.10 Initialization procedure + +The PTM-TC shall be configured during initialization using the same procedure described in clause L.1.10. + +### L.3.11 On-line reconfiguration + +The on-line reconfiguration of the PTM-TC is outside the scope of this Recommendation. There is no specified mechanism to modify the value of the control parameters of the PTM-TC function. The values of *net\_act* and *delay\_act* are automatically updated from the underlying PMS-TC latency path function. + +### **L.3.11.1 Changes to an existing stream** + +Update of the *net\_act* and *delay\_act* parameters of an existing PTM-TC function shall only occur at octet boundaries. The transmit PTM-TC function uses the new values of the *net\_act*, and *delay\_act* to generate octets that follow the signalling of the *Frame.Synchflag.confirm* primitive. The receive PTM-TC function procedures process octets that follow the signalling of the *Frame.Synchflag.indicate* primitive using the new values of these parameters. + +## Annex M + +### Time-of-day distribution over VDSL2 links + +(This annex forms an integral part of this Recommendation.) + +This annex defines the procedure for distribution of time-of-day across a VDSL2 link. Each section in this annex identifies the corresponding clause in the main body for which supplements or amendments are made in support of time-of-day distribution over VDSL2 links. + +#### **M.1 Time-of-day distribution operational overview** + +See clause 8.4.1. + +#### **M.2 Definitions** + +See clause 3. + +#### **M.3 Abbreviations** + +See clause 4. + +#### **M.4 VTU functional model** + +See clause 5.1. + +#### **M.5 TPS-TC function** + +See clause 8 (i.e., text between headings of clause 8 and clause 8.1). + +#### **M.6 eoc communication protocol** + +See clause 8.2.4.1. + +#### **M.7 ToD TPS-TC (ToD-TC)** + +See clause 8.4. + +#### **M.8 Mapping of OH data** + +See clause 9.5.2.2.1. + +#### **M.9 eoc transmission protocol** + +See clause 11.2.2 (transmission protocol). + +See clause 11.2.3.2 (Command and response types). + +#### **M.10 Frequency synchronization command** + +See clause 11.2.3.14. + +##### **M.10.1 The eoc data rate to transport the ToD phase difference values (informative)** + +This informative clause contains a calculation of the required eoc data rate to transport the ToD phase difference values. + +The model of the eoc transmitter is shown in Figure M.1. Two cases are illustrated in Figure M.2. + +- Case 1: Transfer of high priority message ongoing when ToD frequency synchronization message is to be sent; + +- Case 2: Transfer of lower priority message ongoing when ToD frequency synchronization message is to be sent. + +![Figure M.1: Model of the eoc transmitter. The diagram shows four input queues labeled 'High priority', 'Near high priority', 'Medium priority', and 'Low priority', each containing a series of vertical bars representing messages. Arrows from these queues point to a trapezoidal block labeled 'Prio MUX'. An arrow from the 'Prio MUX' block points to a rounded rectangular block labeled 'EOC, message based portion'. The text 'G.993.2(15)_FM.1' is located at the bottom right of the diagram.](fb83b7cd6560e173d6105f928e608613_img.jpg) + +Figure M.1: Model of the eoc transmitter. The diagram shows four input queues labeled 'High priority', 'Near high priority', 'Medium priority', and 'Low priority', each containing a series of vertical bars representing messages. Arrows from these queues point to a trapezoidal block labeled 'Prio MUX'. An arrow from the 'Prio MUX' block points to a rounded rectangular block labeled 'EOC, message based portion'. The text 'G.993.2(15)\_FM.1' is located at the bottom right of the diagram. + +**Figure M.1 – Model of the eoc transmitter** + +Case 1: Transfer of higher priority message ongoing when frequency synchronization message is to be sent + +![Figure M.2: Two cases of ongoing transfers. The diagram is divided into two horizontal sections. The top section, labeled 'Case 1', shows a timeline starting with a 'High(er) priority OHC message, size: M_MAX' of duration T_MAX. A shaded region of duration T_M indicates a transition. The total duration of the cycle is T_SF. The remaining time is labeled 'Freq. synch msg.' with duration T_phdiff. The bottom section, labeled 'Case 2', shows a 'Low(er) priority OHC msg.' of duration T_phdiff, followed by a 'Freq. synch msg.' of duration T_M, and then a 'Low(er) priority OHC message, size: M_MAX' of duration T_MAX. A dashed arrow labeled 'Abort and re-sent' points from the start of the low-priority message to the start of the frequency sync message. Vertical dashed lines with upward arrows at the bottom are labeled 'VTU-O is to send frequency synchronization message i' and 'VTU-O is to send frequency synchronization message i + 1'. The text 'G.993.2(15)_FM.2' is at the bottom right.](14bf833759f6094ed3dda57238e2f9f8_img.jpg) + +Figure M.2: Two cases of ongoing transfers. The diagram is divided into two horizontal sections. The top section, labeled 'Case 1', shows a timeline starting with a 'High(er) priority OHC message, size: M\_MAX' of duration T\_MAX. A shaded region of duration T\_M indicates a transition. The total duration of the cycle is T\_SF. The remaining time is labeled 'Freq. synch msg.' with duration T\_phdiff. The bottom section, labeled 'Case 2', shows a 'Low(er) priority OHC msg.' of duration T\_phdiff, followed by a 'Freq. synch msg.' of duration T\_M, and then a 'Low(er) priority OHC message, size: M\_MAX' of duration T\_MAX. A dashed arrow labeled 'Abort and re-sent' points from the start of the low-priority message to the start of the frequency sync message. Vertical dashed lines with upward arrows at the bottom are labeled 'VTU-O is to send frequency synchronization message i' and 'VTU-O is to send frequency synchronization message i + 1'. The text 'G.993.2(15)\_FM.2' is at the bottom right. + +**Figure M.2 – Two cases of ongoing transfers** + +Variables and Calculation: + +$msg_p$ [Kbit/s] message overhead data rate (Table 9-8) + +$M_{max}$ [Octets] maximum size of any eoc message fragment (1 024 octets, see clause 11.2.3.1) + +$M_{phdiff}$ [Octets] size of periodic ToD frequency synchronization message + +$T_{SF}$ [s] repetition period of time synchronization messages + +$f_{DMT}$ [kHz] DMT symbol rate (clause 10.4.4.) + +$$T_{SF} = \frac{n \times 257}{f_{DMT}} \quad \text{with } n \text{ being agreed between VTUs during initialization} \\ (n = 1, 2 \dots 255)$$ + +$T_{max}$ [s] time required for transmission of message of size $M_{max}$ + +$T_{phdiff}$ [s] time required for transmission of message of size $M_{phdiff}$ + +$T_m = \alpha \times T_{max}$ $\alpha$ denoting a percentage of $T_{max}$ to be considered as margin $T_m$ . The margin takes care for HDLC framing overhead and software reaction times when scheduling OHC messages. + +Condition for deterministic exchange of periodic message along with maximum sized messages: + +$$T_{SF} \geq T_{max} + T_{phdiff} + T_m$$ + +with $msg_p \times T_{max} = M_{max}$ and equivalent for the other contributors, the condition is expressed as + +$$msg_p \geq \frac{8}{T_{SF}} \times (M_{phdiff} + (1 + \alpha) \times M_{max})$$ + +considering the operator configured parameter $msg_{min}$ in addition: + +$$msg_p \geq \min \left\{ \frac{8}{T_{SF}} \times (M_{phdiff} + (1 + \alpha) \times M_{max}); msg_{min} \right\} \quad (M.1)$$ + +Using typical values for the aforementioned parameters, the following table can be generated: + +| n | $f_s$ [kHz] | $T_{SF}$ [s] | $M_{phdiff}$ | $M_{max}$ [Oct] | $\alpha$ | $msg_{min}$ [Kbit/s] | $msg_p$ [Bit/s] | $msg_p$ [Kbit/s] | Percentage of eoc bandwidth for phase difference [%] | +|---|-------------|--------------|--------------|-----------------|----------|----------------------|-----------------|------------------|------------------------------------------------------| +| 1 | 4 | 0.06425 | 5 | 512 | 0.1 | 16 | 70 749 | 71 | 0.9 | + +### M.11 Time synchronization command and responses + +See clause 11.2.3.15. + +### M.12 Updates to initialization + +See clause 12.3.5.2 (SOC messages exchanged during channel analysis and exchange phase). + +See 12.3.5.2.1.1 (O-MSG 1 field #27). + +See 12.3.5.2.1.2 (O-TPS field #7). + +See 12.3.5.2.2.1 (R-MSG 2 fields #9 and #10). + +## Annex N + +### Region D (China) + +(This annex forms an integral part of this Recommendation.) + +#### N.1 Band plans + +This annex defines the band plan for the Chinese region for VDSL2 systems. The band plans are defined in Table N.1 below and can be summarized as follows: + +**Plan CN17** Band plan to $f_{max} = 17.664$ MHz + +**Plan CN35** Band plan to $f_{max} = 35.328$ MHz + +Different variants are defined for band plans CN17 and CN35 to accommodate different underlying services (POTS and ISDN), and different US0 bandwidths. + +NOTE – In the scenario of band plans CN17 and CN35 coexistence, the out-of-band transmit and receive PSDs of CN17 may lead to near-end and far-end crosstalk between lines operating per band plan CN17 and lines operating per band plan CN35. + +**Table N.1 – Band-edge frequencies for Chinese VDSL2 band plans** + +| Band plan | Band-edge frequencies
(as defined in the generic band plan in clause 7.1.2) | | | | | | | | +|-----------|--------------------------------------------------------------------------------|-----------------|--------------|--------------|--------------|--------------|--------------|--------------| +| | $f_{0L}$
kHz | $f_{0H}$
kHz | $f_1$
kHz | $f_2$
kHz | $f_3$
kHz | $f_4$
kHz | $f_5$
kHz | $f_6$
kHz | +| | US0 | | DS1 | | US1 | DS2 | US2 | DS3 | +| CN17 | 25 | 138 | 138 | 3 750 | 5 200 | 14 200 | 17 664 | N/A | +| | 120 | 276 | 276 | | | | | | +| | 25 | 276 | 276 | | | | | | +| | N/A | N/A | 276 | | | | | | +| CN35 | 25 | 138 | 138 | 3 750 | 5 200 | 14 200 | 17 664 | 35 328 | +| | 120 | 276 | 276 | | | | | | +| | 25 | 276 | 276 | | | | | | +| | N/A | N/A | 276 | | | | | | + +NOTE 1 – N/A in the columns $f_{0L}$ and $f_{0H}$ designates a band plan variant that does not use US0. + +NOTE 2 – The capability to support US0 together with profile 17a is required for Chinese VDSL2. + +The $f_i$ in Table N.1 are defined as follows: + +- $f_{0L}$ and $f_{0H}$ : define lower and upper frequency of US0; +- $f_1$ to $f_3$ are the boundary frequencies of the bands DS1 and US1 as defined for CN17; +- $f_4$ to $f_5$ are the boundary frequencies of the bands DS2 and US2 for CN17; +- $f_5$ to $f_6$ are the boundary frequencies of the band DS3 for CN35. + +## N.2 Limit PSD mask options + +The limit PSD mask options defined in this Annex are shown in Table N.2, for various band plans. + +**Table N.2 – Chinese limit PSD mask options for band plans CN17 and CN35** + +| Short name | Limit PSD mask
(long name) | Frequency | | +|------------|-------------------------------|-----------------------------|-----------------------------------------------------------| +| | | US0 type
A/B/M
(Note) | Highest used upstream or
downstream frequency
(kHz) | +| D-1 | CN17-M2x-A | A | 17 664 | +| D-2 | CN17-M2x-B | B | 17 664 | +| D-3 | CN17-M2x-M | M | 17 664 | +| D-4 | CN17- M2x-NUS0-M | N/A | 17 664 | +| D-5 | CN35-M2x-A | A | 35 328 | +| D-6 | CN35-M2x-B | B | 35 328 | +| D-7 | CN35-M2x-M | M | 35 328 | +| D-8 | CN35- M2x-NUS0-M | N/A | 35 328 | + +NOTE – The US0 types stand for: + +- US0 type A corresponds to Annex A of [ITU-T G.993.2 Annex B]; +- US0 type B corresponds to Annex B of [ITU-T G.993.2 Annex B]; +- US0 type M corresponds to Annex M of [ITU-T G.993.2 Annex B]; +- US0 type N/A designates a band plan variant that does not use US0; +- CN17-M2x-NUS0-M and CN35-M2x-NUS0-M designate the variants in which DS1 starts at 276 kHz instead of 138 kHz. + +#### N.2.1 General requirements in the band below 4 kHz + +The noise in the voice band measured with psophometric weighting according to [ITU-T O.41] clause 3.3 shall not exceed –6dBm. The psophometer shall be used in bridging mode and shall be calibrated for 600-ohm termination. + +#### N.2.2 VTU-R limit PSD masks for band plans CN17 and CN35 + +The VTU-R limit PSD masks for band plans CN17 and CN35 are shown in Table N.3. + +**Table N.3 – VTU-R limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|-----------|------------|------------|------------|------------------|------------|------------|------------|------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 0 | –97.5 | –97.5 | –97.5 | –100 | –97.5 | –97.5 | –97.5 | –100 | +| 4 | –97.5 | –97.5 | –97.5 | –100 | –97.5 | –97.5 | –97.5 | –100 | +| 4 | –92.5 | –92.5 | –92.5 | –100 | –92.5 | –92.5 | –92.5 | –100 | +| 25.875 | –34.5 | –92.5 | –37.5 | –100 | –34.5 | –92.5 | –37.5 | –100 | +| 50 | –34.5 | –90 | –37.5 | –100 | –34.5 | –90 | –37.5 | –100 | +| 80 | –34.5 | –81.8 | –37.5 | –100 | –34.5 | –81.8 | –37.5 | –100 | +| 120 | –34.5 | –34.5 | –37.5 | –100 | –34.5 | –34.5 | –37.5 | –100 | +| 138 | –34.5 | –34.5 | –37.5 | –100 | –34.5 | –34.5 | –37.5 | –100 | +| 225 | Interp | –34.5 | –37.5 | –100 | Interp | –34.5 | –37.5 | –100 | +| 243 | –93.2 | –34.5 | –37.5 | –100 | –93.2 | –34.5 | –37.5 | –100 | +| 276 | Interp | –34.5 | –37.5 | –100 | Interp | –34.5 | –37.5 | –100 | +| 307 | Interp | Interp | Interp | –100 | Interp | Interp | Interp | –100 | +| 493.41 | Interp | Interp | –97.9 | –100 | Interp | Interp | –97.9 | –100 | +| 508.8 | Interp | –98 | Interp | –100 | Interp | –98 | Interp | –100 | +| 686 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 3 575 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 3 750 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 3 750 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | +| 5 100 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 5 200 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | +| 5 200 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 5 375 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | + +**Table N.3 – VTU-R limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|------------------|-------------------|-------------------|-------------------|------------------------------|-------------------|-------------------|-------------------|------------------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-
NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-
NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 8 325 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 8 500 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 8 500 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 10 000 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 12 000 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 12 000 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 12 175 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 14 000 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 14 000 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 14 025 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 14 200 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 14 200 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | +| 15 700 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | +| 17 664 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | +| 17 664 | –56.5 | –56.5 | –56.5 | –56.5 | –80 | –80 | –80 | –80 | +| 17 839 | Interp | Interp | Interp | Interp | –100 | –100 | –100 | –100 | +| 21 000 | –80 | –80 | –80 | –80 | –100 | –100 | –100 | –100 | +| 21 450 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 21 450 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 24 715 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 24 890 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 24 890 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | + +**Table N.3 – VTU-R limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|-----------|------------|------------|------------|------------------|------------|------------|------------|------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 25 065 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 30 000 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | -100 | +| 30 000 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| 30 175 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| 35 328 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | +| ≥ 35 328 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | -110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: + +- below 3575 kHz on a dB/log(*f*) basis; and +- above 3575 kHz on a dB/*f* basis. + +### N.2.3 VTU-O limit PSD masks for band plans CN17 and CN35 + +The VTU-O limit PSD masks for band plan CN17 and CN35 are shown in Table N.4. + +**Table N.4 – VTU-O limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|-----------|------------|------------|------------|------------------|------------|------------|------------|------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 0 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | -97.5 | +| 4 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | -92.5 | +| 80 | -72.5 | -92.5 | -92.5 | -92.5 | -72.5 | -92.5 | -92.5 | -92.5 | +| 101.2 | Interp | -92.5 | -92.5 | -92.5 | Interp | -92.5 | -92.5 | -92.5 | + +**Table N.4 – VTU-O limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|------------------|-------------------|-------------------|-------------------|-------------------------|-------------------|-------------------|-------------------|-------------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 138 | –44.2 | Interp | Interp | Interp | –44.2 | Interp | Interp | Interp | +| 138 | –36.5 | Interp | Interp | Interp | –36.5 | Interp | Interp | Interp | +| 227.11 | –36.5 | –62 | –62 | –62 | –36.5 | –62 | –62 | –62 | +| 276 | –36.5 | –48.5 | –48.5 | –48.5 | –36.5 | –48.5 | –48.5 | –48.5 | +| 276 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | +| 1 104 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | –36.5 | +| 1 622 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | –46.5 | +| 2 208 | –48 | –48 | –48 | –48 | –48 | –48 | –48 | –48 | +| 2 249 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 2 500 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 3 750 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | –51.2 | +| 3 750 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 3 925 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 5 025 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 5 200 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 5 200 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | –52.7 | +| 7 050 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 7 225 | Interp | Interp | Interp | Interp | Interp | Interp | Interp | Interp | +| 8 500 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | –54.8 | +| 10 000 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | +| 12 000 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | –55.5 | +| 12 000 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | + +**Table N.4 – VTU-O limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|-----------|------------|------------|------------|------------------|------------|------------|------------|------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| 13 825 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | +| 14 000 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | +| 14 200 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | –56.5 | +| 14 200 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | –80 | +| 14 375 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 17 489 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | –100 | +| 17 664 | –100 | –100 | –100 | –100 | –80 | –80 | –80 | –80 | +| 17 664 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 21 000 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 21 450 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 21 450 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 21 625 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 24 715 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 24 890 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 24 890 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 25 065 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 30 000 | –100 | –100 | –100 | –100 | –56.5 | –56.5 | –56.5 | –56.5 | +| 30 000 | –110 | –110 | –110 | –110 | –73 | –73 | –73 | –73 | +| 30 175 | –110 | –110 | –110 | –110 | Interp | Interp | Interp | Interp | +| 35 328 | –110 | –110 | –110 | –110 | –73.4 | –73.4 | –73.4 | –73.4 | +| 37 000 | –110 | –110 | –110 | –110 | –83 | –83 | –83 | –83 | +| 40 656 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | –110 | + +**Table N.4 – VTU-O limit PSD masks for band plans CN17 and CN35** + +| Name | D-1 | D-2 | D-3 | D-4 | D-5 | D-6 | D-7 | D-8 | +|-----------|------------|------------|------------|------------------|------------|------------|------------|------------------| +| Long name | CN17-M2x-A | CN17-M2x-B | CN17-M2x-M | CN17- M2x-NUS0-M | CN35-M2x-A | CN35-M2x-B | CN35-M2x-M | CN35- M2x-NUS0-M | +| kHz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | dBm/Hz | +| > 40 656 | –110 | –110 | –110 | –110 | -110 | –110 | –110 | –110 | + +NOTE – The PSD values between breakpoints including the values marked by "Interp" shall be obtained by interpolation between adjacent breakpoints as follows: + +- below $f_i$ on a $\text{dB}/\log(f)$ basis; and +- above $f_i$ on a $\text{dB}/f$ basis, + +where $f_i$ is defined in Table N.1 as either 138 or 276 kHz. + +### **N.3 UPBO reference PSDs** + +UPBO parameters '*a*' and '*b*' are set by network management. + +NOTE – The parameters '*a*' and '*b*' are expected to be uniform across all lines sharing a section of cable plant. + +### **N.4 Template PSD** + +#### **N.4.1 Definition** + +The template PSD is set to 3.5 dB below the PSD mask in frequency bands in which the PSD is at or above $-96.5$ dBm/Hz. Elsewhere the template is set to $-100$ dBm/Hz below 4 MHz, $-110$ dBm/Hz between 4 MHz and $f_3$ , or $-112$ dBm/Hz between $f_3$ and 35.328 MHz, where $f_3$ is defined in Table N.1. These values are chosen to satisfy the requirements of clause 7.2.2 in ITU-T G.993.2. + +#### **N.4.2 Narrow-band PSD verification** + +Narrow-band compliance with the PSD masks in this annex shall be verified by power measurements using a 10-kHz measurement bandwidth centred on the frequency in question above 4 kHz, and in a 100-Hz measurement bandwidth in the band up to 4 kHz. + +#### **N.4.3 Use in simulation (informative)** + +The Template PSD may be used in simulations of VDSL2 performance as representative of an average transmitter conformant with the associated limit PSD mask. + +### **N.5 Compliance** + +Compliance requires conformance with at least one limit PSD mask. + +## **Annex O** + +This annex is intentionally left blank. + +## Annex P + +### Short reach VDSL2 with reduced power and enhanced data rate + +(This annex forms an integral part of this Recommendation.) + +#### P.1 Scope + +This annex defines the functional requirements for implementations of ITU-T G.993.2 with reduced power and enhanced data rates over a short reach (e.g., for deployment from the distribution point (DP)). The defined functionalities concern the transmit power, support of enhanced net data rates in [ITU-T G.998.4], SRA and TPS-TC. Other functionalities are for further study. + +#### P.2 Reduced ATP + +A VTU-O compliant with this annex may indicate in the ITU-T G.993.2 discovery phase a MAXNOMATPds parameter value that is lower than the maximum aggregate downstream transmit power in the VDSL2 profile (see Tables 12-21 and 6-1), and lower than the MAXNOMATPds value configured in the CO-MIB (see clause 7.3.1.2.3 of [ITU-T G.997.1]). + +NOTE – The VTU-O MAXNOMATPds parameter value may be lowered due to a specific deployment scenario. + +#### P.3 Minimum bidirectional net data rate capability + +A VTU compliant with this annex shall comply with the following minimum bidirectional net data rate capability for the profiles listed in Table P.1. These values supersede the values specified in Table 6-1. + +Table P.1 – Annex P profiles + +| Frequency plan | Parameter | Parameter value for profile | | +|----------------|-------------------------------------------------------|-----------------------------|------------| +| | | 17a | 30a | +| All | Minimum bidirectional net data rate capability (MBDC) | 150 Mbit/s | 250 Mbit/s | + +NOTE – For the profile 30a in operation according to Annex B, it is recommended that the Limit Mask PSD B8-16 (long name 998ADE30-M2x-NUS0-A) is configured in the CO-MIB. + +Support of profile 30a is mandatory for compliance with this annex. Support of profile 17a is optional. + +#### P.4 ITU-T G.998.4 Annex D support for enhanced net data rates with ITU-T G.998.4 + +Support for ITU-T G.998.4 downstream retransmission is mandatory for a VTU compliant with this annex. + +Support for ITU-T G.998.4 upstream retransmission is optional for a VTU compliant with this annex. + +A VTU compliant with this annex shall support Annex D of ITU-T G.998.4 without requiring bit "ITU-T G.993.5" (see Table 11.68.0.1 of ITU-T G.994.1) to be set to ONE in the Spar(2) octet 2 of ITU-T G.993.2 at the VTU-O. + +A VTU-O compliant with this annex shall set the bit "ITU-T G.998.4 Annex D support" (see Table 11.68.11 of [ITU-T G.994.1]) to ONE in the "ITU-T G.998.4 extensions" NPar(3) field of the CL message. + +A VTU-R compliant with this annex shall set the bit "ITU-T G.998.4 Annex D support" (see Table 11.68.11 of [ITU-T G.994.1]) to ONE in the "ITU-T G.998.4 extensions" NPar(3) field of the CLR message. + +A VTU-O compliant with this annex shall support an AggAchievableNDR\_O equal to the MaxAggAchievableNDR as defined in Annex D of [ITU-T G.998.4] for the respective VDSL2 profile. + +If a VTU-R compliant with this annex supports ITU-T G.998.4 upstream retransmission, it shall support an AggAchievableNDR\_R equal to the MaxAggAchievableNDR, as defined in Annex D of [ITU-T G.998.4] for the respective VDSL2 profile. + +## **P.5 SRA support** + +A VTU-O compliant with this annex shall support OLR type 3: + +- in downstream (i.e., bit s=1 in the field "Downstream OLR capabilities" (see Table 12-52) of the "PMS-TC capabilities of the VTU-O" field in O-MSG1); and +- in upstream (i.e., bit s=1 in the field "Upstream OLR capabilities" (see Table 12-52) of the "PMS-TC capabilities of the VTU-O" field in O-MSG1). + +A VTU-O compliant with this annex shall support OLR type 5: + +- in downstream (i.e., bit s=1 in field #7 "Downstream OLR capabilities with ITU-T G.998.4" (see Table C.4 of [ITU-T G.998.4]) of the "ITU-T G.998.4 parameter field for O-PMS"); and +- in upstream (i.e., bit s=1 in field #8 "Upstream OLR capabilities with ITU-T G.998.4" (see Table C.4 of [ITU-T G.998.4]) of the "ITU-T G.998.4 parameter field for O-PMS"). + +A VTU-R compliant with this annex shall support OLR type 3: + +- in downstream (i.e., bit s=1 in the field "Downstream OLR capabilities" (see Table 12-62) of the "PMS-TC capabilities of VTU-R" field in R-MSG2); and +- in upstream (i.e., bit s=1 in the field "Upstream OLR capabilities" (see Table 12-62) of the "PMS-TC capabilities of VTU-R" field in R-MSG2). + +A VTU-R compliant with this annex shall support OLR type 5 in downstream (i.e., bit s=1 in field #7 "Downstream OLR capabilities with ITU-T G.998.4" (see Table C.6 of [ITU-T G.998.4]) of the "ITU-T G.998.4 parameter field for R-PMS"). + +If a VTU-R compliant with this annex supports ITU-T G.998.4 upstream retransmission, it shall support OLR type 5 in upstream (i.e., bit s=1 in field #8 "Upstream OLR capabilities with ITU-T G.998.4" (see Table C.6 of [ITU-T G.998.4]) of the "ITU-T G.998.4 parameter field for R-PMS"). + +## **P.6 TPS-TC** + +Support of PTM-TC is mandatory for a VTU compliant with this annex. + +## Annex Q + +### Enhanced data rate 35 MHz VDSL2 with 4.3125 kHz subcarrier spacing + +(This annex forms an integral part of this Recommendation.) + +#### Q.1 Scope + +This annex defines functional requirements for implementations of ITU-T G.993.2 operating on frequencies up to 35.324 MHz with subcarrier spacing of 4.3125 kHz, supporting vectoring that is compatible with ITU-T G.993.2 profile 17a. The defined functionalities concern capabilities related to the profile, support of enhanced net data rates in ITU-T G.998.4, SRA and TPS-TC. Other functionalities are for further study. + +#### Q.2 Capabilities related to the profile + +A VTU compliant with this annex shall comply with the following capabilities related to the profiles listed in Table Q.1. The profile 17a values supersede the values specified in Table 6-1. The profile 35b values shall be equal to the profile 30a values listed in Table 6-1, with differences specified in Table Q.1. + +**Table Q.1 – Annex Q profiles** + +| Frequency plan | Parameter | Parameter value for profile | | +|-------------------|----------------------------------------------------------------------------------------------------------------|-----------------------------|--------------------------| +| | | 17a | 35b (Note) | +| All | Maximum aggregate downstream transmit power (dBm) | (no change) | +17 | +| All | Subcarrier spacing (kHz) | (no change) | 4.3125 | +| All | Support of upstream band zero (US0) | (no change) | Regional annex dependent | +| All | Minimum bidirectional net data rate capability (MBDC) | 150 Mbit/s | 400 Mbit/s | +| All | Parameter (1/S) max downstream | (no change) | 48 | +| All | Parameter (1/S) max upstream | (no change) | 24 | +| Annex A (998-35b) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 8191 (35.324) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 2782 (12.0) | +| Annex B (998ADE) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 8191 (35.324) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 2782 (12.0) | +| Annex B (998E) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 8191 (35.324) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 3246 (14.0) | + +**Table Q.1 – Annex Q profiles** + +| Frequency plan | Parameter | Parameter value for profile | | +|-------------------|----------------------------------------------------------------------------------------------------------------|-----------------------------|----------------| +| | | 17a | 35b (Note) | +| Annex N
(CN35) | Index of highest supported downstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 8191 (35.324) | +| | Index of highest supported upstream data-bearing subcarrier (upper band edge frequency in MHz (informative)) | (no change) | 4 095 (17.660) | + +NOTE – Band plans associated with this profile shall have an index of highest supported upstream data-bearing subcarrier not higher than 4095. + +Support of profile 35b is mandatory for compliance with this annex. Support of profile 17a is optional. + +### Q.3 ITU-T G.998.4 Annex D support for enhanced net data rates + +Support for ITU-T G.998.4 downstream retransmission is mandatory for a VTU compliant with this annex. + +NOTE 1 – Setting RTX\_MODEs = 0 (RTX\_FORBIDDEN: ITU-T G.998.4 retransmission not allowed) may result in reduced bit rates and impulse noise protection, and thus is not recommended. + +Support for ITU-T G.998.4 upstream retransmission is optional for a VTU compliant with this annex. + +A VTU compliant with this annex shall support Annex D of [ITU-T G.998.4] without requiring bit "ITU-T G.993.5" (see Table 11.68.0.1 of [ITU-T G.994.1]) to be set to ONE in the Spar(2) octet 2 of ITU-T G.993.2 at the VTU-O. + +A VTU-O compliant with this annex shall set the bit "ITU-T G.998.4 Annex D support" (see Table 11.68.11 of [ITU-T G.994.1]) to ONE in the "ITU-T G.998.4 extensions" NPar(3) field of the CL message. + +A VTU-R compliant with this annex shall set the bit "ITU-T G.998.4 Annex D support2" (see Table 11.68.11 of [ITU-T G.994.1]) to ONE in the 2ITU-T G.998.4 extensions2 NPar(3) field of the CLR message. + +The reference half roundtrip ( $HRT_{ref}$ ) values for determining AggAchievableNDR\_O are the following: + +- Profile 17a: $HRT_{ref}$ = 8 DMT symbols; +- Profile 35b: $HRT_{ref}$ = 6 DMT symbols. + +The reference half roundtrip ( $HRT_{ref}$ ) values for determining AggAchievableNDR\_R are the following: + +- Profile 17a: $HRT_{ref}$ = 8 DMT symbols; +- Profile 35b: $HRT_{ref}$ = 7 DMT symbols. + +NOTE 2 – With nominal values of CE, the $HRT_{ref}$ of 8 symbols, 7 symbols, and 6 symbols are equal to 2 ms, 1.75 ms and 1.5 ms, respectively. + +The maximum aggregate achievable net data rate (MaxAggAchievableNDR, see clause D.1.1.1 of [ITU-T G.998.4]) for each profile, are the following: + +- Profile 17a = 150 Mbit/s; +- Profile 35b = 400 Mbit/s. + +A VTU-O compliant with this annex with support for ITU-T G.998.4 upstream retransmission, shall support an AggAchievableNDR\_O (see clause D.1.1.1 of [ITU-T G.998.4]) equal to the MaxAggAchievableNDR for the profile 17a and equal to 355 Mbit/s for the profile 35b. + +A VTU-R compliant with this annex with support of ITU-T G.998.4 upstream retransmission, shall support an AggAchievableNDR\_R (see clause D.1.1.1 of [ITU-T G.998.4]) equal to the MaxAggAchievableNDR for the profile 17a and equal to 355 Mbit/s for the profile 35b. + +For profile 35b, the valid values for (derived) framing parameters shall be as listed in Table 9-9, Table 9-3 of [ITU-T G.998.4] and Table C.1 of [ITU-T G.998.4] for profile 30a, with differences shown in Table Q.2. + +**Table Q.2 – Valid values for profile 35b** + +| Parameter | downstream | upstream | +|----------------------------------------------------------------------------------------|--------------------------------|--------------------| +| DTU size after FEC in symbols ( $Q \times S_I$ )
(see Table 9.3 of [ITU-T G.998.4]) | $1/3 \leq Q \times S_I \leq 4$ | (no change) | +| DTU size ( $Q \times H$ )
(see Table C.1 of [ITU-T G.998.4]) | $\leq 4096$ | (no change) | +| FEC codewords per symbol ( $1/S$ )
(see Table 9-9) | $\leq 48$ | $\leq 24$ | + +#### **Q.4 SRA support** + +A VTU-O compliant with this annex shall support OLR Type 3: + +- in downstream (i.e., bit s=1 in the Field "Downstream OLR capabilities" (see Table 12-52) of the "PMS-TC capabilities of the VTU-O" field in O-MSG1); and +- in upstream (i.e., bit s=1 in the Field "Upstream OLR capabilities" (see Table 12-52) of the "PMS-TC capabilities of the VTU-O" field in O-MSG1). + +A VTU-O compliant with this annex shall support OLR Type 5: + +- in downstream (i.e., bit s=1 in Field #7 "Downstream OLR capabilities with ITU-T G.998.4" (see Table C.4 of [ITU-T G.998.4]) of the "G.998.4 parameter field for O-PMS"); and +- in upstream (i.e., bit s=1 in Field #8 "Upstream OLR capabilities with ITU-T G.998.4" (see Table C.4 of [ITU-T G.998.4]) of the "G.998.4 parameter field for O-PMS"). + +A VTU-R compliant with this annex shall support OLR Type 3: + +- in downstream (i.e., bit s=1 in the Field "Downstream OLR capabilities" (see Table 12-62) of the "PMS-TC capabilities of VTU-R" field in R-MSG2); and +- in upstream (i.e., bit s=1 in the Field "Upstream OLR capabilities" (see Table 12-62) of the "PMS-TC capabilities of VTU-R" field in R-MSG2). + +A VTU-R compliant with this annex shall support OLR Type 5 in downstream (i.e., bit s=1 in Field #7 "Downstream OLR capabilities with ITU-T G.998.4" (see Table C.6 of [ITU-T G.998.4]) of the "G.998.4 parameter field for R-PMS"). + +If a VTU-R compliant with this annex supports G.998.4 upstream retransmission, it shall support OLR Type 5 in upstream (i.e., bit s=1 in Field #8 "Upstream OLR capabilities with ITU-T G.998.4" (see Table C.6 of [ITU-T G.998.4]) of the "ITU-T G.998.4 parameter field for R-PMS"). + +## Q.5 TPS-TC + +Support of PTM-TC is mandatory for a VTU compliant with this annex. + +## Q.6 Additional changes to ITU-T G.993.2 for operation according to profile 35b + +*NOTE – This clause uses revision marks where changes are made relative to the approved text. Unchanged text is replaced by ellipsis (...).* + +The U reference point specification for operation according to profile 35b shall be the same as specified in the main body of this Recommendation, with differences listed in this clause. + +### 9.5.4 Framing parameters + +... + +**Table 9-8 – Framing parameters for latency path $p$** + +| Parameter | Definition | +|-----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $PERB_p$ |

The number of bytes in the overhead frame:

$PERB_p = \frac{T_p \times N_{FECp}}{M_p} \times \left\lceil \frac{\hat{Q} \times M_p}{T_p \times N_{FECp}} \right\rceil \text{ bytes}$

where:

$\hat{Q} = \begin{cases} Q & \text{if } TDR_p \geq TDR_0 \\ Q \cdot \frac{TDR_p}{TDR_0} & \text{if } TDR_p < TDR_0 \end{cases}$

and where:

TDR_p is the total data rate of latency path p in kbit/s,
Q = 17\,000 bytes for upstream and 34\,000 bytes for downstream,
TDR_0 = 7\,880 kbit/s for upstream and 15\,760 kbit/s for downstream.

| + +... + +### 10.4.1 Data subcarriers + +... + +Transmission will take place on $NSC$ subcarriers, with $NSC_{us} \leq MSI_{us}$ and $NSC_{ds} \leq MSI_{ds}$ ; the subcarrier with index $i=0$ shall not be used. $NSC_{us} + NSC_{ds}$ shall always be less than 8192. + +... + +### 10.4.3 Modulation by the inverse discrete Fourier transform + +... + +The valid values of $N$ are $N = 2^{n+5}$ , where $n$ can take integer values from 0 to 8. The values of $N$ used for upstream and downstream are exchanged during initialization (see clauses 12.3.2, 12.3.3.2.1.3, and 12.3.3.2.2.3). + +... + +### 11.2.3.3 On-line reconfiguration (OLR) commands and responses + +... + +**Table 11-6 – OLR commands sent by the initiating VTU** + +| Name | Length (octets) | Octet number | Content | | Support | | +|-------------------------------|-------------------------------------------|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------|-----------|--| +| Request Type 3 (SRA) (Note 6) | $5 + 7 N_{LP} + 4 N_f$ ( $N_f \leq 128$ ) | 2 | 06 16 (Note 1) | | Mandatory | | +| | | 3 to $2 + 3 N_{LP}$ | $3 \times N_{LP}$ octets containing the new $L_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2 and 3) | | | | +| | | $3 + 3 N_{LP}$ to $2 + 5 N_{LP}$ | $2 \times N_{LP}$ octets containing the new $D_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Note 4) | | | | +| | | $3 + 5 N_{LP}$ to $2 + 6 N_{LP}$ | $N_{LP}$ octets containing the new $T_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2, 3, 5) | | | | +| | | $3 + 6 N_{LP}$ to $2 + 7 N_{LP}$ | $N_{LP}$ octets containing the new $G_p$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2, 3, 5) | | | | +| | | $3 + 7 N_{LP}$ to $2 + 8 N_{LP}$ | $N_{LP}$ octets containing the new $B_{p0}$ values for each of the active latency paths ( $N_{LP}$ = number of active latency paths) (Notes 2, 3, 5) | | | | +| | | $3 + 8 N_{LP}$ to $4 + 8 N_{LP}$ | 2 octets for the number of subcarriers $N_f$ to be modified | | | | +| | | $5 + 8 N_{LP}$ to $4 + 8 N_{LP} + 4 N_f$ | $4 N_f$ octets describing the subcarrier parameter field for each subcarrier | | | | +| | | $5 + 8 N_{LP} + 4 N_f$ | 1 octet for SC | | | | +| Request Type 4 (SOS) | $N_{TG}/2 + 11$ | 2 | 07 16 (Note 1) | | Optional | | +| | | 3 | Message ID | | | | +| | | 4 to $N_{TG}/2 + 3$ | $\Delta b(2)$ | $\Delta b(1)$ | | | +| | | | $\Delta b(4)$ | $\Delta b(3)$ | | | +| | | | ... | | | | +| | | | $\Delta b(N_{TG})$ | $\Delta b(N_{TG} - 1)$ | | | +| | | $N_{TG}/2 + 4$ to $N_{TG}/2 + 6$ | New value for $L_0$ | | | | +| | | $N_{TG}/2 + 7$ to $N_{TG}/2 + 9$ | New value for $L_1$ | | | | +| | | $N_{TG}/2 + 10$ to | New value for $D_0$ | | | | + +**Table 11-6 – OLR commands sent by the initiating VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|------|-----------------|--------------------------------|---------------------|---------| +| | | $N_{TG}/2+11$ | | | +| | | $N_{TG}/2+12$ to $N_{TG}/2+13$ | New value for $D_1$ | | + +... + +### 11.2.3.3 On-line reconfiguration (OLR) commands and responses + +... + +Each subcarrier parameter field shall contain 4 octets formatted as [000i iii iiii iii gggg gggg gggg bbbb] to convey the $g_i$ (12 bits) and the $b_i$ (4 bits) values of the subcarrier index $i$ (13 bits). The subcarrier index $i$ shall be coded in the five LSBs of the first octet and the entire second octet of the subcarrier field. The LSBs of the subcarrier index $i$ shall be contained in the second octet. The $g_i$ shall be contained in the third octet and the four MSBs of the fourth octet. The LSBs of $g_i$ shall be contained in the fourth octet. The $b_i$ shall be contained in the four LSBs of the fourth octet. + +... + +### 11.4.1 Test parameters + +... + +Valid values of $G$ are 1, 2, 4 and 8 for upstream and 1, 2, 4, 8 and 16 for downstream. + +### 12.2.1 Message format + +... + +| Size in octets | Meaning | Value | +|----------------|----------------------|--------------------| +| 1 | Flag | $7E_{16}$ | +| 1 | Address field | Message index | +| 1 | Control field | Segmentation index | +| Up to 2048 | Information payload | Payload bytes | +| 1 | Frame check sequence | FCS | +| 1 | Frame check sequence | FCS | +| 1 | Flag | $7E_{16}$ | + +**Figure 12-4 – Structure of HDLC frames used in the SOC protocol** + +... + +The segmentation index facilitates the message segmentation as described in clause 12.2.6. If no segmentation is used, the segmentation index shall be set to $11_{16}$ . The number of SOC bytes (before byte stuffing) transmitted in a single HDLC frame shall not exceed 2048. + +... + +### 12.2.2.1 Automatic repeat (AR) mode + +... + +**Table 12-5 – HDLC frames in AR mode** + +| Field | Content | +|---------------------|------------------------------------------------------------------------| +| Flag | 7E 16 | +| Message index | 01 16 | +| Segmentation index | 11 16 if not segmented;
as in clause 12.2.6 if segmented | +| Information payload | Variable, up to 2048 bytes | +| FCS | Variable | +| FCS | Variable | +| Flag | 7E 16 | + +... + +### 12.2.6 Segmentation of messages + +Messages that are larger than the maximum allowed size (2048 bytes) shall be segmented before transmission; messages shorter than 2048 bytes may also be segmented to improve robustness. To allow segmentation, a segmentation index is included in the control field of the HDLC frame. The four MSBs of this field shall indicate the number of segments, to a maximum of 15, into which the message has been segmented. The four LSBs of this field shall indicate the index of the current segment, starting from 116. For example, a segmentation index value of 9316 indicates the third segment of a total of nine. In case the message is not segmented, the value of the field shall be 1116. + +... + +### 12.3.2.1.1 CL messages + +... + +**Table 12-9 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|---------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 9 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a, 30a and 35b. Each profile supported by the VTU-O is indicated by setting its corresponding bit to ONE. | +| Initial IDFT Size (2 N ) | This NPar(3) indicates the initial downstream IDFT size that the VTU-O shall use at the beginning of the channel discovery phase.
Bit 5 indicates the use of the extended IDFT size with profile 35b. If set to ONE, it indicates that the IDFT size to be used with profiles 35b is $2N=2\times 8192$ . If set to ZERO, it indicates the profile 35b is not supported.
The 4 LSBs indicate the IDFT size to be used with any profile other than 35b, encoded as a number from 7 to 13 representing $n$ , where IDFT Size $2N = 2^n$ . If no profile other than 35b is supported, the 4 LSBs shall be set to ZERO. | + +### 12.3.2.1.2 MS messages + +**Table 12-12 – VTU-O MS message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|--------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 9 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a, 30a and 35b. The profile selected by the VTU-O is indicated by setting its corresponding bit to ONE. | + +### 12.3.2.2.1 CLR messages + +**Table 12-15 – VTU-R CLR message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|--------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 9 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a, 30a and 35b. Each profile supported by the VTU-R is indicated by setting its corresponding bit to ONE. | +| Initial IDFT Size ( $2N$ ) |

This NPar(3) indicates the initial upstream IDFT size that the VTU-R shall use at the beginning of the channel discovery phase.

The bit 5 indicates whether the extended IDFT size shall be used with the profile 35b (ONE) or not (ZERO). If set to ONE, the IDFT size to be used with profiles 35b is 2N=2\times 8192. If set to ZERO, the IDFT size to be used with profiles 35b is 2N=2\times 4096.

The 4 LSBs indicate the IDFT size to be used with any profile other than 35b, encoded as a number from 6 to 13 representing n, where IDFTsize 2N=2^n. If no profile other than 35b is supported, the 4 LSBs shall be set to ZERO.

| + +### 12.3.2.2.2 MS messages + +**Table 12-18 – VTU-R MS message NPar(3) bit definitions** + +| ITU-T G.994.1
SPar(2) Bit | Definition of NPar(3) bits | +|--------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Profiles | Each valid profile is represented by one bit in a field of 9 bits. The valid profiles are: 8a, 8b, 8c, 8d, 12a, 12b, 17a, 30a and 35b. The profile selected by the VTU-R is indicated by setting its corresponding bit to ONE. | + +#### 12.3.3.2.1.1 O-SIGNATURE + +... + +Fields #2 and #3 shall be formatted as "bands descriptors". The format of the bands descriptor shall be as shown in Table 12-22. + +**Table 12-22 – Bands descriptor** + +| Octet | Content of field | +|---------------------|----------------------------------------------------------------------------------------------------------| +| 1 | Number of bands to be described | +| 2-5 | Bits 0-15: Index of the first subcarrier in band 1
Bits 16-31: Index of the last subcarrier in band 1 | +| 6-9 (if applicable) | Bits 0-15: Index of the first subcarrier in band 2
Bits 16-31: Index of the last subcarrier in band 2 | +| etc. | etc. | + +The first octet of the bands descriptor shall contain the number of bands to be described. This number can be zero. In that case, there shall be no further octets in the descriptor. If the number of bands is not equal to zero, each group of four consecutive octets in the descriptor shall describe the first and last subcarrier in a band. + +The first 16 bits (0-15) in the group of four octets shall contain the index of the subcarrier at the lower edge of the band. The last 16 bits (16-31) shall contain the index of the subcarrier at the upper edge of the band. The first and last subcarriers shall be included in the band. For example, a field value 18000E0016 means that all subcarriers from 0E0016 = 3 584 to 180016 = 6 144, including subcarriers 3 584 and 6 144, are included in the set. + +... + +**Table 12-23 – PSD descriptor** + +| Octet | Content of field | +|---------------------|---------------------------------------------------------------------------------------------------------------------------------| +| 1 | Number of subcarriers (or breakpoints) being described | +| 2-5 | Bits 0-15: Index of first subcarrier being described
Bits 16-31: PSD level in steps of 0.1 dB with an offset of –140 dBm/Hz | +| 6-9 (if applicable) | Bits 0-15: Index of second subcarrier being described
Bits 16-31: PSD level in steps of 0.1 dB with an offset of –140 dBm/Hz | +| etc. | etc. | + +The first octet of the descriptor shall contain the number of breakpoints being specified. This number can be zero. In that case, there shall be no additional octets in the descriptor. If the number of breakpoints is not equal to zero, each group of four consecutive octets shall describe one breakpoint as a PSD value at a certain subcarrier index. + +The first 16 bits (0-15) in the group of three octets shall contain the index of the subcarrier. The last 16 bits (16-31) shall contain the PSD level. The PSD level shall be an integer multiple of 0.1 dB with an offset of –140 dBm/Hz. For example a field value of 0320180016 means a PSD of 32016 × 0.1 – 140 = –60 dBm/Hz on subcarrier index 180016 = 6 144. The PSD level of intermediate unspecified subcarriers shall be obtained using a linear interpolation between the given PSD points (in dBm/Hz) with the frequency axis expressed in a linear scale. The subcarrier indices of the specified breakpoints may be either determined by the CO-MIB or vendor discretionary. + +... + +Field #13 "Downstream transmit window length ( $\beta_{ds}$ )" shall contain the length of the downstream transmit window, ( $\beta_{ds}$ ), expressed in multiples of 2 samples at the downstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be coded as an 8-bit integer. + +NOTE – The phrase "expressed in multiples of 2" means that the actual value used in the transceiver is 2 times the value represented in the field. + +Field #14 "Downstream cyclic prefix" shall contain the length of the downstream cyclic prefix expressed in multiples of 2 samples at the downstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be coded as a 16-bit integer. + +Field #15 "Initial value of timing advance" indicates the initial timing advance, and shall be expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples at the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be encoded in a 16-bit field using twos complement format. The special value of $7FFF_{16}$ indicates that the VTU-R shall select the initial setting of the timing advance. + +... + +#### 12.3.3.2.1.2 O-UPDATE + +... + +Field #4 "Highest allowed upstream subcarrier" contains the index of the highest frequency upstream subcarrier that is allowed to be used by the VTU-R. The format shall be a 16-bit value. The subcarrier index shall be described as 13 bits. The three MSBs of the field shall be set to ZERO. The VTU-R shall not allocate power to subcarriers above the highest allowed upstream subcarrier. + +Field #5 "Lowest allowed upstream subcarrier" contains the index of the lowest-frequency upstream subcarrier that is allowed to be used by the VTU-R. The format shall be a 16-bit value. The subcarrier index shall be described as 13 bits. The three MSBs of the field shall be set to ZERO. The VTU-R shall not allocate power to subcarriers below the lowest allowed upstream subcarrier. + +... + +Field #7 "Timing advance correction" contains the timing advance correction with respect to the currently used timing advance expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples at the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be encoded in a 16-bit field using twos complement format. Positive values shall indicate that the transmitted symbol will be advanced more with respect to the received symbol. + +... + +#### 12.3.3.2.1.3 O-PRM + +... + +Field #5 "Downstream cyclic prefix length" contains the value of $L_{CP}$ that shall be applied in the downstream direction starting from the beginning of the training phase. The value shall be expressed in multiples of 2 samples of the downstream sampling rate corresponding to the IDFT size communicated in Field #7. The format shall be the same as for Field #14 of the O-SIGNATURE message (Table 12-21). + +Field #6 "Downstream transmit window length ( $\beta_{ds}$ )" contains the length of the transmit window that shall be used in the downstream direction starting from the beginning of the training phase. The value shall be expressed in multiples of 2 samples of the downstream sampling rate corresponding to the IDFT size communicated in Field #7. The format shall be the same as for Field #13 of the O-SIGNATURE message (Table 12-21). + +Field #7 "VTU-O IDFT size" indicates the updated size of the IDFT at the VTU-O that shall be used in the downstream direction starting from the beginning of the training phase. This value may be different from the initial value that was exchanged during the ITU-T G.994.1 handshake phase. The value shall be expressed as the IDFT size $2N_{ds}$ . The format shall be an 8-bit field coded as $\log_2(2N_{ds})$ with valid values from 7 to 14. + +... + +**Table 12-31 – Log\_tssi descriptor** + +| Octet | Content of field | +|---------------------|-------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Number of breakpoints (subcarriers) to be described | +| 2-5 | Bits 0-15: Subcarrier index of the first breakpoint
Bits 16-31: $\log\_tss_i$ value of the first breakpoint in steps of 0.1 dB | +| 6-9 (if applicable) | Bits 0-15: Subcarrier index of the second breakpoint
Bits 16-31: $\log\_tss_i$ value of the second breakpoint in steps of 0.1 dB | +| etc. | etc. | + +The first octet of the descriptor shall contain the number of breakpoints being specified. This number can be zero. In that case, there shall be no further octets in the descriptor, and the field shall be interpreted as all $\log\_tss_i = 0$ for all transmitted subcarriers. If the number of breakpoints is not equal to zero, each group of four consecutive octets shall describe one breakpoint as a $\log\_tss_i$ value (see clause 10.3.4.3) at a certain subcarrier index. The $tss_i$ values shall be determined by the transmitter such that, with combined frequency domain and time domain spectrum shaping, the downstream PSD at the U interface during the training phase and subsequent initialization phases shall be identical to the value MREFPSDds. + +The first 16 bits (0-15) in the group of four octets shall contain the index of the subcarrier. The last 16 bits (16-31) shall contain the $\log\_tss_i$ value of the subcarrier in dB calculated as specified in clause 10.3.4.3, such that the maximum $\log\_tss_i$ value across all breakpoints shall be 0 dB. Each $\log\_tss_i$ value shall be an integer multiple of -0.1 dB. The receiver shall obtain the $\log\_tss_i$ values for unspecified subcarriers using a linear interpolation between the $\log\_tss_i$ values of the assigned breakpoints as specified in clause 10.3.4.3. + +... + +#### 12.3.3.2.2.1 R-MSG 1 + +... + +**Table 12-33 – Tone descriptor** + +| Octet | Content of field | +|---------------------|-----------------------------------------------------------| +| 1 | Number of tones | +| 2-5 | Bits 0-15: index of tone 1
Bits 16-31: index of tone 2 | +| 6-9 (if applicable) | Bits 0-15: index of tone 3
Bits 16-31: index of tone 4 | +| etc. | etc. | + +The first octet of the tone descriptor shall contain the number of pilot tones selected by the VTU-R. If this number is zero, there shall be no further octets in the descriptor. If the number of tones is not equal to zero, each group of four consecutive octets in the descriptor shall describe the location of two pilot tones. + +The first 16 bits (0-15) and the last 16 bits (16-31) in each group of four octets shall contain the indices of two tones. For example, a field value $18000E00_{16}$ means tone $0E00_{16} = 3\,584$ and tone $1800_{16} = 6\,144$ . If the number of pilot tones is odd, the last 16 bits in the field shall be set to ZERO. + +Field #6 "Timing advance" indicates the timing advance selected by the VTU-R (which is either the initial value conveyed by the O-SIGNATURE message or a vendor-discretionary setting if no initial value was set by the VTU-O). It shall be expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples at the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be encoded in a 16-bit field using twos complement format. + +... + +Field #8 "Upstream transmit window length ( $\beta_{us}$ )" contains the length of the transmit window that shall be used in the upstream direction during the channel discovery phase. The value shall be expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples of the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The format shall be the same as for Field #13 of the O-SIGNATURE message (Table 12-21). + +Field #9 "Upstream cyclic prefix length" contains the length of the upstream cyclic prefix expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples of the upstream sampling rate corresponding to the IDFT size communicated during the ITU-T G.994.1 handshake phase. The value shall be coded as a 16-bit unsigned integer. + +... + +### 12.3.3.2.2.3 R-PRM + +... + +Field #4 "Upstream cyclic prefix length" contains the value of the cyclic prefix that shall be applied in the upstream direction starting from the beginning of the training phase. The value shall be expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples of the upstream sampling rate corresponding to the IDFT size communicated in Field #6. The format of the selected cyclic prefix length shall be the same as for Field #14 of the O-SIGNATURE message (Table 12-21). + +NOTE 1 – Profile 35b being used with extended IDFT Size is equivalent with Field #6 having value 14. + +NOTE 2 – The value of the CE length used in the calculation of the upstream cyclic prefix length is the value communicated in O-PRM, not the one sent in R-UPDATE. + +Field #5 "Upstream transmit window length ( $\beta_{us}$ )" contains the length of the transmit window that shall be used in the upstream direction starting from the beginning of the training phase. The value shall be expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples of the upstream sampling rate corresponding to the IDFT size communicated in Field #6. The format shall be the same as for Field #13 of the O-SIGNATURE message (Table 12-21). + +Field #6 "VTU-R IDFT size" communicates the IDFT size, $2N_{us}$ , that shall be used by the VTU-R starting from the beginning of the training phase. The format shall be an 8-bit field coded as $\log_2(2N_{us})$ , with valid values from 6 to 14. This value may be different from the initial value that was exchanged during the ITU-T G.994.1 handshake phase. + +... + +#### 12.3.4.2.1.1 O-TA\_UPDATE + +... + +Field #2 "Timing advance correction" defines the timing advance correction that shall be used with respect to the current timing advance. It shall be expressed either in multiples of 2 samples if profile 35b is used with extended IDFT Size, or otherwise, in samples at the upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. Positive values shall indicate that the transmitted symbol will be advanced more with respect to the received symbol. + +... + +#### 12.3.4.2.2.1 R-TA\_UPDATE + +... + +Field #2 "Current timing advance" gives the timing advance currently being used by the VTU-R. The field is expressed either in multiples of 2 samples if profile 35b is used with extended IDFT size, or otherwise, in samples at the upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. + +Field #3 "Timing advance correction" indicates the timing advance correction, with respect to the current timing advance, preferred by the VTU-R either in multiples of 2 samples if profile 35b is used with extended IDFT size, or otherwise, in samples at the upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. Positive values shall indicate that the transmitted symbol will be advanced more with respect to the received symbol. + +Field #4 "Maximum value of timing advance" indicates the maximum value of timing advance that the VTU-R can accommodate either in multiples of 2 samples if profile 35b is used with extended IDFT size, or otherwise, in samples at the current upstream sampling rate corresponding to the IDFT size communicated in Field #6 of R-PRM. The value shall be encoded in a 16-bit field using twos complement format. + +... + +### 12.3.5.2.1.3 O-PMS + +... + +**Table 12-57 – Latency path descriptor** + +| Octet | Field | Format | Description | +|------------|-------|---------|----------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | T | 1 byte | The number of MDFs in an OH subframe for the latency path; $T = k \times M$ , where $k$ is an integer. The value of $T$ shall not exceed 64. | +| 2 | G | 1 byte | The total number of overhead octets in an OH subframe for the latency path; $1 \leq G \leq 32$ . | +| 3 | F | 1 byte | Number of OH frames in the OH superframe for the latency path. $1 \leq F \leq 255$ . | +| 4 | M | 1 byte | The number of MDFs in an RS codeword for the latency path. Only the values 1, 2, 4, 8, 16 are allowable. | +| 5, 6 and 7 | L | 3 bytes | Contains the value of $L$ for the latency path. | +| 8 | R | 1 byte | Contains the value of $R$ for the latency path. | +| 9 | I | 1 byte | Contains the value of $I$ for the latency path. | +| 10 and 11 | D | 2 bytes | Interleaver depth $D$ for the latency path. | + +**Table 12-58 – ROC descriptor** + +| Octet | Field | Format | Description | +|------------|-------|---------|-----------------------------------------------------------------------------------------------------------------------------------------| +| 1 | T | 1 byte | The number of MDFs in an OH subframe of the ROC. $T = k \times M$ , where $k$ is an integer. The value of $T$ shall not exceed 64. | +| 2 | G | 1 byte | The total number of overhead octets in an OH subframe of the ROC; The valid values of $G$ are $1 \leq G \leq 32$ . | +| 3 | F | 1 byte | Number of OH frames in the OH superframe for the ROC. The value of $F$ shall be 1. | +| 4 | M | 1 byte | The number of MDFs in an RS codeword for the ROC. The valid values of $M$ are 1, 2, 4, 8 and 16. | +| 5, 6 and 7 | L | 3 bytes | Contains the value of $L$ for the ROC. The valid values of $L$ are from 8 to 128 in multiples of 8. | +| 8 | R | 1 byte | Contains the value of $R$ for the ROC. The value of $R$ shall be 16. | +| 9 | I | 1 byte | Contains the value of $I$ for the ROC. $I$ shall be set to $I = M \times (G/T) + R$ . The valid values of $I$ are $32 \leq I \leq 66$ . | +| 10 and 11 | D | 2 bytes | Interleaver depth $D$ for the ROC. The valid values of $D$ are $1 \leq D \leq 20$ . | + +... + +### 12.3.5.2.1.4 O-PMD + +... + +**Table 12-59 – Description of message O-PMD** + +| | Field name | Format | +|-------------------------------------------------------------------------------------------|-------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Message descriptor | Message code | +| 2 | Trellis | 1 byte | +| 3 | Bits and gains table | $2 \times NSC_{us}$ bytes | +| 4 | Tone ordering table | $4 \times \lceil NSC_{us}/2 \rceil$ bytes coded as follows:
  • • Bits 0-15: t_{2n-1}
  • • Bits 16-31: t_{2n}
| +| 5 | Initialization status | 1 byte | +| 6 | ITU-T G.998.4 parameter field | Variable length | +| 7 | ITU-T G.993.5 parameter field | Variable length | +| NOTE – The $\lceil x \rceil$ notation represents rounding to the nearest greater integer. | | | + +... + +Field #4 "Tone ordering table" contains the tone ordering table $t$ for the upstream direction. The tone ordering table contains the order in which the subcarriers shall be assigned bits in the upstream direction. The table shall include all subcarriers of the MEDLEYus set and only these subcarriers. Each subcarrier index shall be represented as a 16-bit value. Pairs of subcarrier indices shall be mapped to a field of 4 bytes as shown in Table 12-59. For example, if the value of the $n^{\text{th}}$ field is 1800100016, $t_{2n-1} = 1000_{16} = 4\,096$ and $t_{2n} = 1800_{16} = 6\,144$ . If the number of subcarriers in the MEDLEYus set is odd, the last 16 bits of the field shall be set to ZERO (and ignored by the receiver). The value of the first index sent shall be equal to the index of the first entry in the tone ordering table ( $t_1$ , see clause 10.3.1). The remaining indices shall be sent in increasing order of the tone ordering table $t$ entries ( $t_2, t_3, \dots, t_{NSC_{us}}$ ). + +... + +**12.3.5.2.2.4 R-PMD** + +... + +**Table 12-65 – Description of message R-PMD** + +| | Field name | Format | +|-------------------------------------------------------------------------------------------|-------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Message descriptor | Message code | +| 2 | Trellis | 1 byte | +| 3 | Bits and gains table | $2 \times NSC_{ds}$ bytes | +| 4 | Tone ordering table | $4 \times \lceil NSC_{ds}/2 \rceil$ bytes coded as follows:
  • • Bits 0-15: t_{2n-1}
  • • Bits 16-31: t_{2n}
| +| 5 | Showtime pilot tones | Tone descriptor | +| 6 | Initialization status | 1 byte | +| 7 | ITU-T G.998.4 parameter field | Variable length | +| 8 | ITU-T G.993.5 parameter field | Variable length | +| NOTE – The $\lceil x \rceil$ notation represents rounding to the nearest greater integer. | | | + +... + +Field #4 "Tone ordering table" contains the tone ordering table $t$ for the downstream direction. The tone ordering table contains the order in which the subcarriers shall be assigned bits in the downstream direction. The table shall include all subcarriers of the MEDLEYds set and only these subcarriers. Each subcarrier index shall be represented as a 16-bit value. Pairs of subcarrier indices shall be mapped to a field of 4 bytes as shown in Table 12-65. For example, if the value of the $n^{\text{th}}$ field is $18001000_{16}$ , $t_{2n-1} = 1000_{16} = 4\,096$ and $t_{2n} = 1800_{16} = 6\,144$ . If the number of subcarriers in the MEDLEYds set is odd, the last 16 bits of the field shall be set to ZERO (and ignored by the receiver). The value of the first index sent shall be equal to the index of the first entry in the tone ordering table ( $t_1$ , see clause 10.3.1). The remaining indices shall be sent in increasing order of the tone ordering table $t$ entries ( $t_2, t_3, \dots, t_{\text{NSCds}}$ ). + +... + +## Q.7 Additional changes to ITU-T G.998.4 for operation according to profile 35b + +*NOTE – This clause uses revision marks where changes are made relative to the approved text. Unchanged text is replaced by ellipsis (...).* + +The U reference point specification for operation according to profile 35b shall be the same as specified in [ITU-T G.998.4] for operation with ITU-T G.993.2, with differences listed in this clause. + +### C.3.2 On-line reconfiguration (OLR) commands and responses + +... + +**Table C.11 – OLR commands sent by the initiating VTUName** + +| | Length (octets) | Octet number | Content | Support | +|-------------------------------------|-------------------------------|-----------------|------------------------------------------------------------------------------|-----------| +| Request Type 5 (SRA/ ITU-T G.998.4) | $14+4 N_f$ ( $N_f \leq 128$ ) | 2 | $08_{16}$ | Mandatory | +| | | 3-5 | three octets containing the new value for $L_I$ | | +| | | 6 | one octet containing the new value for $B_{I0}$ | | +| | | 7 | one octet containing the new value for $M_I$ | | +| | | 8 | one octet containing the new value for $R_I$ | | +| | | 9 | one octet containing the new value for $Q$ | | +| | | 10 | one octet containing the new value for $V$ | | +| | | 11 | one octet containing the new value for $Q_{ix}$ | | +| | | 12 | one octet containing the new value for $Ib$ | | +| | | 13 – 14 | 2 octets for the number of subcarriers $N_f$ to be modified | | +| | | 15 – $14+4 N_f$ | $4 N_f$ octets describing the subcarrier parameter field for each subcarrier | | +| | | $15+4 N_f$ | 1 octet for SC | | + +**Table C.11 – OLR commands sent by the initiating VTUName** + +| | Length (octets) | Octet number | Content | | Support | | +|-------------------------------------|-----------------|------------------------------|-------------------------------------------------|------------------------|----------|--| +| Request Type 6 (SOS/ ITU-T G.998.4) | $N_{TG}/2+12$ | 2 | 09 16 | | Optional | | +| | | 3 | Message ID | | | | +| | | 4 to $N_{TG}/2+3$ | $\Delta b(2)$ | $\Delta b(1)$ | | | +| | | | $\Delta b(4)$ | $\Delta b(3)$ | | | +| | | | ... | | | | +| | | | $\Delta b(N_{TG})$ | $\Delta b(N_{TG} - 1)$ | | | +| | | $N_{TG}/2+4$ to $N_{TG}/2+6$ | three octets containing the new value for $L_1$ | | | | +| | | $N_{TG}/2+7$ | one octet containing the new value for $B_{10}$ | | | | +| | | $N_{TG}/2+8$ | one octet containing the new value for $M_1$ | | | | +| | | $N_{TG}/2+9$ | one octet containing the new value for $R_1$ | | | | +| | | $N_{TG}/2+10$ | one octet containing the new value for $Q$ | | | | +| | | $N_{TG}/2+11$ | one octet containing the new value for $V$ | | | | +| | | $N_{TG}/2+12$ | one octet containing the new value for $Q_{ix}$ | | | | +| | | $N_{TG}/2+13$ | one octet containing the new value for $Ib$ | | | | + +... + +## **Annex R** + +This annex is intentionally left blank. + +## **Annex S** + +This annex is intentionally left blank. + +## **Annex T** + +This annex is intentionally left blank. + +## **Annex U** + +This annex is intentionally left blank. + +## **Annex V** + +This annex is intentionally left blank. + +## **Annex W** + +This annex is intentionally left blank. + +## Annex X + +### ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction + +(This annex forms an integral part of this Recommendation.) + +This annex provides the necessary and sufficient additional requirements for ITU-T G.993.2 operation to allow cancellation of the downstream crosstalk from lines with ITU-T G.993.2 Annex X VTU-Rs into lines with ITU-T G.993.5 VTU-Rs (both connected to ITU-T G.993.5-capable VTU-Os). + +This includes: + +- Requirements for the ITU-T G.993.2 Annex X VTU-O downstream transmit signals; +- Requirements for the ITU-T G.993.2 Annex X VTU-R downstream receiver to be immune to the ITU-T G.993.2 Annex X VTU-O downstream transmit signals sent by the VTU-O during Initialization and Showtime. The VTU-R shall be immune to the VTU-O sending pilot sequences on the probe tones (as defined in [ITU-T G.993.5]) of the sync symbols during showtime. + +A VTU-O supporting operation according to this annex shall also support operation according to [ITU-T G.993.5]. + +This annex reflects changes to the main body of this Recommendation to allow ITU-T G.993.5-friendly operation of ITU-T G.993.2 in the downstream direction. The clauses below indicate changes to specific clauses of this Recommendation. + +NOTE – Simultaneous initialization of a line operating per this annex and a line operating per [ITU-T G.993.5] or per ITU-T G.993.2 Annex O only supports downstream vectoring. + +#### X.1 Power management commands and responses (clause 11.2.3.9) + +The same power management commands and responses shall be used as defined in clause 11.2.3.9. The orderly shutdown procedures described in clauses 11.2.3.9.1 and 11.2.3.9.2 shall be modified as defined in this clause. + +##### X.1.1 L3 Request by VTU-R (replaces clause 11.2.3.9.1) + +Upon receipt of the L3 Request command, the responding VTU-O shall send either the Grant or Reject response. The proposed link state shall be formatted as 0316 for the L3 link state. If any other link state is received, the Reject response shall be sent with the reason code 0216. + +The VTU-O may reject a request to move to link state L3 using reason code 0116 because it is temporarily busy, or reject it using code 0316 because it has local knowledge that the L3 state is not desired at this time. + +If the VTU-R receives the Grant response, the VTU-R shall transmit zero power on all subcarriers. The VTU-R shall make no action causing changes to the characteristics of the transmission path. When the VTU-O observes the stopped transmission, it shall also stop transmitting. When the VTU-R observes the stopped transmission, it may perform at its own discretion functions that change characteristics of the transmission path. + +##### X.1.2 L3 Request by VTU-O (replaces clause 11.2.3.9.2) + +Upon receipt of the L3 Request command, the responding VTU-R shall send either the Grant or Reject response. The proposed link state shall be formatted as 0316 for the L3 link state. If any other link state is received, the Reject response shall be sent with the reason code 0216. + +The VTU-R may reject a request to move to link state L3 using reason code 0116 because it is temporarily too busy, or reject it using code 0316 because it has local knowledge that the L3 state is not desired at this time. + +If the VTU-O receives the Grant response, the VTU-O shall transmit zero power on all subcarriers. The VTU-O shall make no actions causing changes to the characteristics of the transmission path. When the VTU-R observes the stopped transmission, it shall also stop transmitting. When the VTU-O observes the stopped transmission, it may perform at its own discretion functions that change characteristics of the transmission path. + +## X.2 Initialization procedure (supplements clause 12.3) + +If and only if the ITU-T G.994.1 VTU-O MS message or VTU-R MS message the NPar(2) bit "ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction" is set to ONE, the VTU-O shall use a modified ITU-T G.993.2 initialization procedure, as defined in this annex. + +This initialization procedure is identical to an ITU-T G.993.2 initialization procedure, except for the channel discovery phase and the training phase. + +As applicable to the VTU-O, this initialization procedure defines two new signals to be transmitted. + +As applicable to the VTU-R, this initialization procedure requires these two new signals to be ignored. + +### X.2.1 ITU-T G.994.1 handshake phase + +#### X.2.1.1 Handshake – VTU-O + +##### X.2.1.1.1 CL messages (supplements clause 12.3.2.1.1) + +Table 12-7 shall be extended with Table X.1 as follows: + +**Table X.1 – VTU-O CL message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|-------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5-friendly
ITU-T G.993.2 operation
in the downstream
direction |

This bit shall be set to ONE, if and only if the VTU-O supports Annex X and Annex X is allowed via the CO-MIB (i.e., VECTORMODE_ENABLE bit 1 is set to 1, see clause 7.3.1.13.9 of [ITU-T G.997.1]).

If set to ONE, indicates the capability of the VTU-O to comply with all requirements of this annex, including:

  • • to send O-P-VECTOR-1 (as defined in [ITU-T G.993.5]) during initialization after O-P-QUIET and before O-P-CHANNEL DISCOVERY 1, and
  • • to send O-P-VECTOR-1-1 (as defined in [ITU-T G.993.5]) during initialization after O-P-SYNCHRO 3 and before O-P-TRAINING 1, and
  • • to send pilot sequences on the probe tones (as defined in [ITU-T G.993.5]) of the sync symbols during showtime.

If set to ONE, and the CO-MIB VECTORMODE_ENABLE bit 3 is set to 1 (see clause 7.3.1.13.9 of [ITU-T G.997.1]), then the ITU-T G.993.5 SPar(2) bit shall also be set to ONE.

| + +### X.2.1.1.2 MS messages (supplements clause 12.3.2.1.2) + +Table 12-10 shall be extended with Table X.2 as follows: + +**Table X.2 – VTU-O MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|-------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5-friendly
ITU-T G.993.2 operation
in the downstream
direction |

Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that both the VTU-O and VTU-R shall operate in compliance with all requirements of this annex, including that the VTU-O shall:

  • • send O-P-VECTOR-1 (as defined in [ITU-T G.993.5]) during initialization after O-P-QUIET and before O-P-CHANNEL DISCOVERY 1, and
  • • send O-P-VECTOR-1-1 (as defined in [ITU-T G.993.5]) during initialization after O-P-SYNCHRO 3 and before O-P-TRAINING 1, and
  • • send pilot sequences on the probe tones (as defined in [ITU-T G.993.5]) of the sync symbols during showtime.

NOTE – If this bit is set to ONE, bits "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" and "ITU-T G.993.5" are set to ZERO in the VTU-O MS message.

| + +### X.2.1.2 Handshake – VTU-R + +#### X.2.1.2.1 CLR messages (supplements clause 12.3.2.2.1) + +Table 12-13 shall be extended with Table X.3 as follows: + +**Table X.3 – VTU-R CLR message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|--------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5-friendly
ITU-T G.993.2 operation
in the downstream
direction |

Set to ONE if the VTU-R is compliant with all requirements of this annex, including being immune to a VTU-O

  • • sending O-P-VECTOR-1 (as defined in [ITU-T G.993.5]) after O-P-QUIET and before O-P-CHANNEL DISCOVERY 1, and
  • • sending O-P-VECTOR-1-1 (as defined in [ITU-T G.993.5]) during initialization after O-P-SYNCHRO 3 and before O-P-TRAINING 1, and
  • • sending pilot sequences on the probe tones (as defined in [ITU-T G.993.5]) of the sync symbols during showtime.

If set to ONE, the ITU-T G.993.5 SPar(2) bit shall be set to ZERO (see Note).

| +| NOTE – A VTU-R that has ITU-T G.993.5 capability enabled sets this NPar(2) bit to 0. | | + +### X.2.1.2.2 MS messages (supplements clause 12.3.2.2.2) + +Table 12-16 shall be extended with Table X.4 as follows: + +**Table X.4 – VTU-R MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|-------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5-friendly
ITU-T G.993.2 operation
in the downstream
direction |

Set to ONE if and only if both the last previous CLR and the last previous CL message have set this bit to ONE. If set to ONE, indicates that both the VTU-O and VTU-R shall operate in compliance with all requirements of this annex, including that the VTU-O shall:

  • • send O-P-VECTOR-1 (as defined in [ITU-T G.993.5]) after O-P-QUIET and before O-P-CHANNEL DISCOVERY 1, and
  • • send O-P-VECTOR-1-1 (as defined in [ITU-T G.993.5]) during initialization after O-P-SYNCHRO 3 and before O-P-TRAINING 1, and
  • • send pilot sequences on the probe tones (as defined in [ITU-T G.993.5]) of the sync symbols during showtime.

NOTE – If this bit is set to ONE, bits "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" and "ITU-T G.993.5" are set to ZERO in the VTU-R MS message.

| + +## X.2.2 Channel discovery phase + +### X.2.2.1 Overview (supplements clause 12.3.3.1) + +Figure X.1 replaces Figure 12-6. Figure X.1 highlights the signals added and the signals/messages modified in the ITU-T G.993.2 channel discovery phase for operation according to this annex. Non-highlighted signals and messages shall be as defined in the main body of this Recommendation. + +The VTU-O shall initiate the start of the channel discovery phase with O-P-QUIET 1 as defined in clause 12.3.3.1. + +When in the ITU-T G.994.1 VTU-O MS message or VTU-R MS message the NPar(2) bit "ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction" is set to ONE, the VTU-O shall use a modified ITU-T G.993.2 initialization procedure, by insertion of ITU-T G.993.5 O-P-VECTOR 1 of duration no longer than $1\,024 \times 257$ symbols after O-P-QUIET 1. + +NOTE – As applicable to the VTU-O, this channel discovery phase is identical to an ITU-T G.993.5 channel discovery phase with all segments x-P-VECTOR y-z set to zero length, except for O-P-VECTOR 1. + +After completing the O-P-VECTOR 1 stage, the VTU-O shall start transmitting O-P-CHANNEL DISCOVERY 1 and proceed as defined in clause 12.3.3.1. + +![Timing diagram for the stages of the channel discovery phase showing Downstream and Upstream signals and SOC messages over time.](54ab5749327b822e800fc41bafa685c1_img.jpg) + +The diagram illustrates the timing of the channel discovery phase between a Downstream (left) and an Upstream (right) entity. Vertical dashed lines indicate time intervals, and horizontal dashed lines separate different signal levels. + +**Downstream (Left):** + +- SOC Messages:** O-IDLE, O-SIGNATURE (yellow), O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, O-IDLE. +- Signals:** ITU-T G.994.1 Handshake, O-P-QUIET 1, O-P-VECTOR 1 (yellow), O-P-CHANNEL-DISCOVERY1, O-P-SYNCHRO 1, O-P-QUIET 2 / O-P-PILOT 1 (hatched), O-P-PERIODIC 1, O-P-SYNCHRO 2, O-P-CHANNEL-DISCOVERY 2, O-P-SYNCHRO 3. + +**Upstream (Right):** + +- Signals:** ITU-T G.994.1 Handshake, R-P-QUIET 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1, R-P-LINEPROBE (hatched), R-P-PERIODIC 1, R-P-SYNCHRO 2, R-P-CHANNEL-DISCOVERY 2, R-P-SYNCHRO 3. +- SOC Messages:** R-IDLE, R-MSG 1, R-IDLE, R-UPDATE, R-IDLE, R-PRM, R-IDLE. + +**Vertical Labels:** + +- Left: CHANNEL DISCOVERY phase (VTU-O) +- Right: CHANNEL DISCOVERY phase (VTU-R) + +G.993.2(15)\_FX.1 + +Timing diagram for the stages of the channel discovery phase showing Downstream and Upstream signals and SOC messages over time. + +Figure X.1 – Timing diagram for the stages of the channel discovery phase + +Table 12-19 shall be extended with Table X.5 as follows: + +**Table X.5 – VTU-O signals and SOC messages in the channel discovery phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages | SOC state | +|--------------|---------------|----------------------------------------|--------------|-----------| +| O-P-VECTOR 1 | ITU-T G.993.5 | $4 \times 257$ to $1\,024 \times 257$ | None | Inactive | + +**X.2.2.1.1 SOC message exchange during the channel discovery phase (supplements clause 12.3.3.2)** + +**X.2.2.1.1.1 VTU-O messages sent during the channel discovery phase (supplements clause 12.3.3.2.1)** + +**X.2.2.1.1.1.1 O-SIGNATURE (supplements clause 12.3.3.2.1.1)** + +Table 12-21 field #23 shall be replaced with Table X.5a field #23 as follows: + +**Table X.5a – Description of message O-SIGNATURE** + +| | Field name | Format | +|----|---------------------------------|--------| +| 23 | O-P-VECTOR 1-1 maximum duration | 1 byte | + +Field #23 "O-P-VECTOR 1-1 maximum duration" field indicates the maximum duration of the O-P-VECTOR 1-1 signal, as defined in Table X.6. The three LSBs shall represent the value of $n$ in the range 0 to 7 and the five MSBs shall be set to 0. + +**X.2.2.2 Signals transmitted during the channel discovery phase (supplements clause 12.3.3.3)** + +O-P-VECTOR 1 shall comply with the general requirements for signals transmitted during the channel discovery phase. + +**X.2.2.2.1 Signals transmitted by the VTU-O** + +**X.2.2.2.1.1 O-P-VECTOR 1-1 (supplements clause 12.3.4.3.1 preceding clause 12.3.3.3.1.1)** + +O-P-VECTOR 1-1 shall be as defined in [ITU-T G.993.5]. + +**X.2.2.2.1.2 O-P-VECTOR 1 (supplements clause 12.3.3.3.1 between clauses 12.3.3.3.1.1 and 12.3.3.3.1.2)** + +O-P-VECTOR 1 shall be as defined in [ITU-T G.993.5]. + +**X.2.2.2.1.3 O-P-SYNCHRO 3 (replaces clause 12.3.3.3.1.9)** + +O-P-SYNCHRO 3 is a signal that provides an exact time marker for transitions from O-P-CHANNEL DISCOVERY 2 to O-P-VECTOR 1-1 (training phase). + +O-P-SYNCHRO 3 shall be identical to O-P-SYNCHRO 1. + +**X.2.3 Training phase** + +**X.2.3.1 Overview (supplements clause 12.3.4.1)** + +Figure X.2 replaces Figure 12-8. Figure X.2 highlights the signals added and the signals/messages modified in the ITU-T G.993.2 training phase for operation according to this annex. Non-highlighted signals and messages shall be as defined in the main body of this Recommendation. + +![Timing diagram for the stages of the training phase showing Downstream and Upstream signals and SOC messages over time.](f34d4741036e8407888cd90a70d1a624_img.jpg) + +The diagram illustrates the timing of signals and messages during the training phase, divided into Downstream and Upstream directions. Vertical double-headed arrows on the left and right indicate the duration of the TRAINING phase (VTU-O and VTU-R respectively). + +| Downstream SOC Messages | Downstream Signals | Upstream Signals | Upstream SOC Messages | +|--------------------------|--------------------|------------------|--------------------------| +| [TRAINING phase (VTU-O)] | O-P-VECTOR 1-1 | R-P-QUIET 2 | [TRAINING phase (VTU-R)] | +| | O-P-TRAINING 1 | | | +| | O-P-SYNCHRO 4 | R-P-TRAINING 1 | | +| | | R-P-SYNCHRO 4 | | +| | O-P-PILOT 2 | | | +| | | R-P-TEQ | | +| | O-P-ECT | | | +| | | R-P-QUIET 3 | | +| | O-P-TEQ | | | +| | | R-P-ECT | | +| O-IDLE | O-P-PILOT 3 | | R-IDLE | +| O-TA_UPDATE | O-P-PERIODIC 2 | | R-TA_UPDATE | +| O-IDLE | | | R-IDLE | +| | O-P-SYNCHRO 5 | | R-ACK | +| | | | R-IDLE | +| | | R-P-SYNCHRO 5 | | + +Timing diagram for the stages of the training phase showing Downstream and Upstream signals and SOC messages over time. + +G.993.2(15)\_FX.2 + +Figure X.2 – Timing diagram for the stages of the training phase + +When in the ITU-T G.994.1 VTU-O MS message or VTU-R MS message the NPar(2) bit "ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction" is set to ONE, at the start of the training phase, the VTU-O shall transmit O-P-VECTOR 1-1, and the VTU-R shall be silent (R-P-QUIET 2). O-P-VECTOR 1-1 shall be followed by O-P-TRAINING 1, while the VTU-R is still silent (R-P-QUIET 2). The remainder of the initialization procedure shall be as defined in clause 12.3.4.1. + +NOTE – As applicable to the VTU-O, this training phase is identical to an ITU-T G.993.5 training phase with all segments x-P-VECTOR y-z set to zero length except for O-P-VECTOR 1-1. + +Table 12-39 shall be extended with Table X.6 as follows: + +**Table X.6 – VTU-O signals and SOC messages in the training phase** + +| Signal | Signal type | Signal duration in DMT symbols with CE | SOC messages | SOC state | +|----------------------------------------------------------------------------------------------------------------------------------|---------------|-----------------------------------------------------------------------------------------|--------------|-----------| +| O-P-VECTOR 1-1 | ITU-T G.993.5 | $4 \times 257$ to
$(n+1) \times 1\,024 \times 257$ ,
with $n=0\dots 7$ (see Note) | None | Inactive | +| NOTE – The value of $n$ is communicated to the VTU-R in O-SIGNATURE message during the channel discovery phase (see Table X.5a). | | | | | + +### X.2.3.2 Signals transmitted during the training phase (supplements clause 12.3.4.3) + +O-P-VECTOR 1-1 shall comply with the general requirements for signals transmitted in the training phase. + +#### X.2.3.2.1 Signals transmitted by the VTU-O + +## Annex Y + +### Full ITU-T G.993.5-friendly ITU-T G.993.2 operation + +(This annex forms an integral part of this Recommendation.) + +This annex provides the necessary and sufficient additional requirements for ITU-T G.993.2 operation to allow cancellation of the downstream and upstream crosstalk from lines with ITU-T G.993.2 Annex Y VTU-Rs into lines with ITU-T G.993.5 VTU-Rs (both connected to ITU-T G.993.5-capable VTU-Os that also support upstream vectoring). + +NOTE 1 – These requirements also allow cancellation of the upstream crosstalk from lines with ITU-T G.993.5 VTU-Rs into lines with ITU-T G.993.2 Annex Y VTU-Rs (both connected to ITU-T G.993.5-capable VTU-Os). + +A VTU-O supporting operation according to this annex shall also support [ITU-T G.993.5] with support of upstream vectoring. + +NOTE 2 – Indication of support of ITU-T G.993.5 upstream vectoring in the VTU-O CL message, together with indicating support of ITU-T G.993.2 Annex Y, does not imply a requirement for cancellation of upstream crosstalk from lines with ITU-T G.993.5 VTU-Rs into a line operating according to ITU-T G.993.2 Annex Y. + +NOTE 3 – A VTU-R supporting operation according to this annex supports all functionality of ITU-T G.993.5 (including change of the upstream pilot sequence), except for the clipped error sample feedback during initialization (support of R-ERROR-FEEDBACK message is not required) and Showtime (support of the backchannel is not required). + +This annex reflects changes to the main body of this Recommendation and [ITU-T G.993.5]. The clauses below indicate changes to specific clauses of Recommendation ITU-T G.993.2 and [ITU-T G.993.5]. + +#### **Y.1 Initialization procedure (supplements clause 12.3)** + +If and only if the ITU-T G.994.1 VTU-O MS message or VTU-R MS message the NPar(2) bit "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" is set to ONE, the VTU-O and VTU-R shall use the a modified ITU-T G.993.5 initialization procedure, as defined in this annex. If, in addition, NPar(2) bit "Upstream FDPS in full ITU-T G.993.5-friendly ITU-T G.993.2 operation" is set to ONE, the VTU-O and VTU-R shall also support upstream frequency dependent pilot sequences (FDPS) as defined in ITU-T G.993.5. + +This initialization procedure is identical to an ITU-T G.993.5 initialization procedure, except for the initialization messages R-MSG 1, O\_TA-UPDATE, and O-PMS and for the initialization signal R-P-VECTOR 2 (during which the message R-ERROR-FEEDBACK is not transmitted). + +##### **Y.1.1 ITU-T G.994.1 handshake phase** + +###### **Y.1.1.1 Handshake – VTU-O** + +###### **Y.1.1.1.1 CL messages (supplements clause 12.3.2.1.1 of ITU-T G.993.2)** + +Table 12-7 shall be extended with Table Y.1 as follows: + +**Table Y.1 – VTU-O CL message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|--------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | This bit shall be set to ONE, if and only if the VTU-O supports Annex Y and Annex Y is allowed via the CO-MIB (i.e., VECTORMODE_ENABLE bit 2 is set to 1, see clause 7.3.1.13.9 of [ITU-T G.997.1]).
If set to ONE, indicates that the VTU-O supports compliance with this annex (full ITU-T G.993.5-friendly ITU-T G.993.2 operation).
If set to ONE, and the CO-MIB VECTORMODE_ENABLE bit 3 is set to 1 (see clause 7.3.1.13.9 of [ITU-T G.997.1]), then both the ITU-T G.993.5 SPar(2) bit and the related "Upstream vectoring" NPar(3) bit shall also be set to ONE. | +| Pilot sequence length multiple of 4 in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | If set to ONE, this bit indicates the VTU-O supports pilot sequence lengths that are a multiple of 4. If set to ZERO, this bit indicates the VTU-O only supports pilot sequence lengths that are a power of 2.
If set to ONE, the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit shall also be set to ONE. | +| Upstream FDPS in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | If set to ONE, indicates that the VTU-O supports upstream FDPS as defined in ITU-T G.993.5 when in full ITU-T G.993.5-friendly ITU-T G.993.2 operation.
If set to ONE, the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit shall also be set to ONE. | + +**Y.1.1.1.2 MS messages (supplements clause 12.3.2.1.2 of ITU-T G.993.2)** + +Table 12-10 shall be extended with Table Y.2 as follows: + +**Table Y.2 – VTU-O MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|--------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE.
If set to ONE, both the VTU-O and VTU-R shall operate as defined in this annex.

NOTE – If set to ONE, the bit "ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction" (see Annex X) and the bit "ITU-T G.993.5" are both set to ZERO in the VTU-O MS message. | +| Pilot sequence length multiple of 4 in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | This bit shall be set to ONE if and only if set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "pilot sequence length multiple of 4" is enabled. If set to ZERO, this bit indicates only pilot sequence lengths that are a power of 2 are enabled.
If the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit is set to ZERO in the VTU-O MS message, then this bit shall be ignored by the VTU-R. | + +**Table Y.2 – VTU-O MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|----------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Upstream FDPS in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE.
If set to ONE, both the VTU-O and VTU-R shall operate as defined in this annex and support upstream FDPS.
If the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit is set to ZERO in the VTU-O MS message, then this bit shall be ignored by the VTU-R. | + +**Y.1.1.2 Handshake – VTU-R****Y.1.1.2.1 CLR messages (supplements clause 12.3.2.2.1 of ITU-T G.993.2)** + +Table 12-13 shall be extended with Table Y.3 as follows: + +**Table Y.3 – VTU-R CLR message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|--------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | If set to ONE, indicates that the VTU-R supports full compliance with this annex (ITU-T G.993.5-friendly ITU-T G.993.2 operation).
If set to ONE, the ITU-T G.993.5 SPar(2) bit shall be set to ZERO (see Note). | +| Pilot sequence length multiple of 4 in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | If set to ONE, this bit indicates the VTU-R supports pilot sequence lengths that are a multiple of 4. If set to ZERO, this bit indicates the VTU-R only supports pilot sequence lengths that are a power of 2.
If set to ONE, the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit shall also be set to ONE. | +| Upstream FDPS in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | If set to ONE, indicates that the VTU-R supports upstream FDPS as defined in ITU-T G.993.5 when in full ITU-T G.993.5-friendly ITU-T G.993.2 operation.
If set to ONE, the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit shall also be set to ONE. | +| NOTE – A VTU-R that has ITU-T G.993.5 capability enabled sets this NPar(2) bit to 0. | | + +**Y.1.1.2.2 MS messages (supplements clause 12.3.2.2.2 of ITU-T G.993.2)** + +Table 12-16 shall be extended with Table Y.4 as follows: + +**Table Y.4 – VTU-R MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|-----------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Full ITU-T G.993.5-friendly ITU-T G.993.2 operation | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE.
If set to ONE, both the VTU-O and VTU-R shall operate as defined in this annex.
NOTE – If set to ONE, the bit "ITU-T G.993.5-friendly ITU-T G.993.2 operation in the downstream direction" (see Annex X) and the bit "ITU-T G.993.5" are both set to ZERO in the VTU-R MS message. | + +**Table Y.4 – VTU-R MS message NPar(2) bit definitions** + +| ITU-T G.994.1
NPar(2) bit | Definition of NPar(2) bit | +|-------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Pilot sequence length multiple of 4 in full ITU-TG.993.5-friendly ITU-T G.993.2 operation | This bit shall be set to ONE if and only if set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "pilot sequence length multiple of 4" is enabled. If set to ZERO, this bit indicates only pilot sequence lengths that are a power of 2 are enabled. If the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit is set to ZERO in the VTU-R MS message, then this bit shall be ignored by the VTU-O. | +| Upstream FDPS in full ITU-T G.993.5-friendly ITU-T G.993.2 operation | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, both the VTU-O and VTU-R shall operate as defined in this annex and support upstream FDPS. If the "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" bit is set to ZERO in the VTU-R MS message, then this bit shall be ignored by the VTU-O. | + +## Y.2 R-MSG1 (supplements clause 10.3.2.2 of [ITU-T G.993.5]) + +Field #2, "Maximum number of FEXT estimation symbols per super-frame", defines the maximum number ( $K_{max}$ ) of symbols in the super-frame for which the VTU-R supports error sample reporting. The field shall be formatted as an unsigned integer with value $K_{max} = 0$ . + +Field #3, "Support of optional backchannel control parameters", indicate the optional values of control parameters supported by the VTU-R. The field shall be formatted as an unsigned integer with value $00_{16}$ . + +## Y.3 O-TA\_UPDATE (supplements clause 10.4.2.1 of [ITU-T G.993.5]) + +Field #2, "Error report control parameters", defines the control parameters for each of the vectored bands indicated in O-SIGNATURE. The VTU-R shall ignore the error report control parameters. + +Field #3, "SOC Repetition Factor", defines the SOC repetition factor, $1/R$ , as set by the VCE. The field shall be represented as an unsigned integer with value $1/R = 10$ . + +Field #4, "FEXT estimation symbols per super-frame", defines the number of symbols ( $K$ ) in the super-frame for which a clipped error sample shall be reported. The field shall be formatted as an unsigned integer with value $K = 0$ . + +## Y.4 R-P-VECTOR 2 (replaces clause 10.4.4.5 of [ITU-T G.993.5]) + +At sync symbol positions, the R-P-VECTOR 2 signal shall contain sync symbols, modulated as defined for the R-P-VECTOR 1 signal. At other symbol positions, the symbols shall be modulated as for the R-P-TRAINING 2 signal, with the extended SOC channel being established. + +Transmission of R-P-VECTOR 2 enables the VCE to estimate upstream FEXT channels from the vectored lines into the initializing line and update the estimates of the upstream FEXT from the initializing lines into the vectored lines. + +During the sync symbols, the SOC is in the inactive state. During the other symbols, the SOC is in the active state, and the VTU-R shall transmit the R-IDLE message. + +The duration of R-P-VECTOR 2 signal is controlled by the VTU-O. Within 64 symbols after the last symbol of the O-P-SYNCHRO V4 signal, the VTU-R shall end the transmission of the R-P-VECTOR 2 signal. + +The R-P-VECTOR 2 signal shall be followed by the R-P-SYNCHRO V2 signal. + +NOTE – The R-P-VECTOR 2 signal is identical to the ITU-T G.993.5 R-P-VECTOR 2 signal without extended SOC and with the VTU-R transmitting R-IDLE messages instead of R-ERROR-FEEDBACK messages. + +#### **Y.5 O-PMS (supplements clause 10.5.2.1 of [ITU-T G.993.5])** + +Field #2, "Showtime backchannel encapsulation", defines whether the Showtime backchannel is encapsulated into eoc messages or into Layer 2 Ethernet packets. The VTU-R shall ignore this field. + +Field #3, "Layer 2 VCE MAC Address", defines the VCE MAC Address to be used by the NT as MAC destination address in case Layer 2 Ethernet encapsulation is used. The VTU-R shall ignore this field. + +Field #4, "Layer 2 Line\_ID", defines the Line\_ID to be used by the NT in case Layer 2 Ethernet encapsulation is used. The VTU-R shall ignore this field. + +#### **Y.6 eoc messages for backchannel configuration (replaces clause 8.1 of [ITU-T G.993.5])** + +During Showtime, the VTU-O shall not send a backchannel configuration eoc command. + +NOTE – At the start of Showtime, the backchannel is inactive. In absence of activation by the VTU-O through a backchannel configuration eoc command, the backchannel remains inactive throughout Showtime. + +#### **Y.7 Loop diagnostic mode procedures (replaces clause 12.4)** + +The loop diagnostic mode procedure is identical to the ITU-T G.993.5 loop diagnostic mode procedure. + +## Appendix I + +### Example values of DPBO parameters to protect ADSL2plus for clause C.3 + +(This appendix does not form an integral part of this Recommendation.) + +This appendix defines example values of DPBO parameters defined in clause 7.3.1.2.13 of [ITU-T G.997.1]. + +These example values are for reducing crosstalk to ADSL2plus. + +The set of breakpoints defining PSDMASKds( $t_i$ , $PSD_i$ ) should be monotonic in frequency, i.e., $t_i \leq t_{i+1}$ for $0 < i \leq 32$ , except when the DPBOLFO function is used. An interruption in the monotonic frequency progression indicates that DPBOLFO is requested and that the breakpoints following the interruption are for the DPBOLFO. + +NOTE – PSDMASKds in this appendix is the ITU-T G.997.1 parameter that is referred to as MIBMASKds in this Recommendation. + +#### I.1 Example PSD parameters + +In this clause, PSD parameters to define PEPSD( $f$ ), PSDMASKds( $f$ ) and DPBOMPSD( $f$ ) are described. In Table I.1, DPBOEPSD, DPBOPSDMASKds( $f$ ), DPBOLFO and DPBOMUS are defined. + +Table I.1 – PSD parameters of DPBO + +| | DPBOEPSD
(dBm/Hz) | DPBOPSDMASKds
(dBm/Hz) | DPBOLFO
(dBm/Hz) | DPBOMUS
(dBm/Hz) | +|------------------------|-----------------------------|-----------------------------------------|----------------------------|----------------------------| +| VDSL2 in the building | Limit PSD mask = Table C.5 | Limit PSD mask = Table C.9 | -100 | -100 | +| VDSL2 from the cabinet | Limit PSD mask = Table C.5 | Limit PSD mask = Table C.5 or Table C.6 | | | + +#### I.2 Example Cable parameters + +In this clause, cable parameters to define PEPSD( $f$ ) are exemplified. PEPSD( $f$ ) is defined as the following equation: + +$$PEPSD(f) = DPBOEPSD(f) - (DPBOESCM A + DPBOESCM B \cdot \sqrt{f} + DPBOESCM C \cdot f) DPBOESEL$$ + +In Table I.2, DPBOESCM A, DPBOESCM B and DPBOESCM C are defined. + +Table I.2 – E-side cable model + +| | DPBOESCM A
(No-dimension) | DPBOESCM B
(1/√MHz) | DPBOESCM C
(1/MHz) | +|------------------------|----------------------------------------------------------------------|-------------------------------|------------------------------| +| VDSL2 in the building | $-10 \text{Log} \left( \frac{DPBOESEL + DPBORSEL}{DPBORSEL} \right)$ | 1 | 0 | +| VDSL2 from the cabinet | | | | + +$DPBOESEL = \text{length}(m) \times 1(\sqrt{\text{MHz}}) \times 0.0259 \left( \text{dB}/[m\sqrt{\text{MHz}}] \right)$ ; with $\text{length}$ (m) equal to the distance in metres between CO and Cabinet (for Japanese cable). + +$DPBORSEL = length(m) \times 1(\sqrt{MHz}) \times 0.0259 (dB/[m\sqrt{MHz}])$ ; with *length* (m) equal to the distance in metres between Cabinet and VTU-R (for Japanese cable). + +### I.3 Example frequency parameters + +In this clause, frequency parameters to define a frequency range where DPBO is in action are described. In Table I.3, DPBOFMIN is from which DPBO starts and DPBOFMAX is at which DPBO ends. + +**Table I.3 – Frequency range of DPBO** + +| | DPBOFMIN
(kHz) | DPBOFMAX
(kHz) | +|------------------------|----------------------------------|----------------------------------| +| VDSL2 in the building | 138 | 2 208 | +| VDSL2 from the cabinet | | | + +## Appendix II + +### Impact of loop and VTU impedance mismatch on the Hlog accuracy + +(This appendix does not form an integral part of this Recommendation.) + +This appendix provides a discussion regarding the effects on measured accuracy of $H\log(f)$ when there is a mismatch between a nominal loop termination impedance of $100\ \Omega$ and the actual termination impedance ( $Z_{VTU}$ ) provided by the VTU. This appendix is meant to provide additional technical details regarding the accuracy requirements for the $H\log(k \times G \times \Delta f)$ test parameter. + +Figure II.1 shows the reference diagram for computing reference received PSD with a spectrum or network analyzer. + +![Figure II.1: Measurement of received PSD by network or spectrum analyzer. The diagram shows a circuit loop with an impedance Z_loop connected to a voltage source V_TX (PSD_TX) and a load resistor R_N. The voltage across R_N is V_N, which is measured to determine the Power Spectral Density PSD_N. The diagram is labeled G.993.2(15)_FII.1.](584e66af1afdf8cd35b8c8795179813b_img.jpg) + +Figure II.1: Measurement of received PSD by network or spectrum analyzer. The diagram shows a circuit loop with an impedance Z\_loop connected to a voltage source V\_TX (PSD\_TX) and a load resistor R\_N. The voltage across R\_N is V\_N, which is measured to determine the Power Spectral Density PSD\_N. The diagram is labeled G.993.2(15)\_FII.1. + +**Figure II.1 – Measurement of received PSD by network or spectrum analyzer** + +$Z_{loop}$ is the impedance of the loop as seen by the network analyzer looking into the test loop. This loop impedance is dependent on the loop topology and may vary with frequency. + +$R_N$ is the input impedance of the network analyzer and we assume $R_N = 100\ \Omega$ . This value is independent of frequency. + +The power spectral density of the received signal as seen by the network analyzer may be represented as: + +$$PSD_N = \frac{|V_{Tx}|^2}{\Delta f} \cdot \frac{R_N}{|Z_{loop} + R_N|^2} \quad (\text{II.1})$$ + +with $\Delta f$ representing the subcarrier spacing of 4.3125 kHz. + +Figure II.2 shows the reference diagram for computing the PSD received by the VTU. + +![Figure II.2: Measurement of PSD received by VTU. The diagram shows a circuit loop with an impedance Z_loop connected to a voltage source V_TX (PSD_TX) and a load impedance Z_ATU. The voltage across Z_ATU is V_ATU, which is measured to determine the Power Spectral Density PSD_ATU. The diagram is labeled G.993.2(15)_FII.2.](e09182684e5dcc9eea6d91f8b2d3c080_img.jpg) + +Figure II.2: Measurement of PSD received by VTU. The diagram shows a circuit loop with an impedance Z\_loop connected to a voltage source V\_TX (PSD\_TX) and a load impedance Z\_ATU. The voltage across Z\_ATU is V\_ATU, which is measured to determine the Power Spectral Density PSD\_ATU. The diagram is labeled G.993.2(15)\_FII.2. + +**Figure II.2 – Measurement of PSD received by VTU** + +$Z_{loop}$ is the same loop impedance as for the reference case above in Figure II.1; this is the impedance of the line seen by the VTU looking into the loop. + +$Z_{VTU}$ is the input impedance of the VTU as seen by the test loop. + +The power spectral density of the received signal as seen by the VTU may be represented as: + +$$PSD_{ATU} = \frac{|V_{Tx}|^2}{\Delta f} \cdot \frac{|Z_{ATU}|}{|Z_{loop} + Z_{ATU}|^2} \quad (\text{II.2})$$ + +with $\Delta f$ representing the subcarrier spacing of 4.3125 kHz. + +The difference between equations (II.1) and (II.2) is the error in the receive PSD. Assuming that the transmit PSDs are identical for each case, this difference would represent the error in the $H\log(k \times G \times \Delta f)$ measurement. Hence, the $H\log(k \times G \times \Delta f)$ error in dB may be represented as follows: + +$$Error_{dB} = 10 \cdot \log \left( \frac{PSD_N}{PSD_{ATU}} \right) = 10 \cdot \log \left( \frac{(R_N)}{|Z_{ATU}|} \cdot \frac{|Z_{ATU} + Z_{loop}|^2}{|R_N + Z_{loop}|^2} \right) \quad (\text{II.3})$$ + +The above error expression in dB per equation (II.3) also represents the (contribution of $Z_{loop}$ and $Z_{VTU}$ variation to the) $H\log(k \times G \times \Delta f)$ accuracy in dB. + +Figure II.3 shows a plot of the $H\log(f)$ error in dB vs. the VTU input impedance, for different loop impedances that vary from 10 $\Omega$ to 200 $\Omega$ . + +![Figure II.3: A line graph showing the Hlog error (dB) on the y-axis (ranging from -4.00 to 7.00) versus the ATU input impedance (Ohms) on the x-axis (ranging from 0 to 300). Multiple curves are plotted, each representing a different loop impedance (Zloop) ranging from 10 Ohms to 200 Ohms. All curves intersect at 100 Ohms on the x-axis, where the Hlog error is 0 dB. For Zloop values below 100 Ohms, the error is negative for input impedances below 100 Ohms and positive for input impedances above 100 Ohms. For Zloop values above 100 Ohms, the error is positive for input impedances below 100 Ohms and negative for input impedances above 100 Ohms. The magnitude of the error increases as the input impedance deviates from 100 Ohms and as the loop impedance deviates from 100 Ohms.](62d99bc0ede1ff01d2cc3f98e48db361_img.jpg) + +Figure II.3: A line graph showing the Hlog error (dB) on the y-axis (ranging from -4.00 to 7.00) versus the ATU input impedance (Ohms) on the x-axis (ranging from 0 to 300). Multiple curves are plotted, each representing a different loop impedance (Zloop) ranging from 10 Ohms to 200 Ohms. All curves intersect at 100 Ohms on the x-axis, where the Hlog error is 0 dB. For Zloop values below 100 Ohms, the error is negative for input impedances below 100 Ohms and positive for input impedances above 100 Ohms. For Zloop values above 100 Ohms, the error is positive for input impedances below 100 Ohms and negative for input impedances above 100 Ohms. The magnitude of the error increases as the input impedance deviates from 100 Ohms and as the loop impedance deviates from 100 Ohms. + +G.993.2(15)\_FII.3 + +**Figure II.3 – $H\log(f)$ error in dB as a function of loop and VTU impedance variations** + +Regarding the variation of $H\log(f)$ error with input impedances, the following can be observed: + +- This Recommendation does not define any input impedance requirements for VTUs. Similarly, this Recommendation does not define any requirements on return loss. Therefore, VTU implementers are free to design for any input impedance to optimize VTU performance; +- Although it can be observed that the transmit PSD is reported relative to 100 $\Omega$ , the loop impedance will generally be different from 100 $\Omega$ and the resulting transmit PSD will vary accordingly; +- The VTU input impedance varies among those from different manufacturers; + +- The VTU input impedance varies with frequency, which is dependent on implementation; +- If the VTU input impedance is equal to the reference impedance of the network analyzer, i.e., $Z_{VTU} = R_N$ , and everything else is perfect, then the error is zero; +- The curves in Figure II.3 do not include any tolerance for components inside the VTU. This tolerance is implementation dependent. + +The actual input impedance of a VTU is complex. The impedance values shown in Figure II.3 are the equivalent real Ohmic values. + +## Bibliography + +[b-ATIS-0600023] ATIS-0600023 (2008) – *Guidance for the Use of Upstream Power Back Off Parameters for ITU-T Recommendation G.993.2 Annex A.* + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9963-202306-I_PDF-E/00504fc688ebcf131ccbeff94dfc9939_img.jpg b/marked/G/T-REC-G.9963-202306-I_PDF-E/00504fc688ebcf131ccbeff94dfc9939_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..a0b08b11ce7ede4332f7e0955c3cd9cb476e7df5 --- /dev/null +++ b/marked/G/T-REC-G.9963-202306-I_PDF-E/00504fc688ebcf131ccbeff94dfc9939_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:3b8664eeabf9214966126ae0a382c7b6212eccbb4315e12ccf637d09640dade0 +size 88056 diff --git a/marked/G/T-REC-G.9963-202306-I_PDF-E/0538daaa5583c23e17db3a12f2281a55_img.jpg b/marked/G/T-REC-G.9963-202306-I_PDF-E/0538daaa5583c23e17db3a12f2281a55_img.jpg new file mode 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b/marked/G/T-REC-G.9977-201602-I_PDF-E/raw.md @@ -0,0 +1,1157 @@ + + +International Telecommunication Union + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9977** + +(02/2016) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – In premises networks + +--- + +**Mitigation of interference between DSL and PLC** + +Recommendation ITU-T G.9977 + +ITU-T + +![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in blue, with "ITU" in a larger, bold font above it. + +ITU logo + +International +Telecommunication +Union + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9977 + +# Mitigation of interference between DSL and PLC + +## Summary + +Recommendation ITU-T G.9977 specifies functionality of a mechanism to mitigate interference caused by in-home powerline communication (PLC) devices to an x-type digital subscriber line (xDSL) network termination (implementing transceivers in compliance with ITU-T Recommendations such as ITU-T G.993.2 and ITU-T G.9701). This Recommendation addresses various in-home network types and wiring topologies. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.9977 | 2016-02-26 | 15 | 11.1002/1000/12548 | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2016 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-----------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 3 | +| 5 Conventions ..... | 4 | +| 6 Reference models..... | 4 | +| 6.1 Generalized reference model ..... | 4 | +| 6.2 Details of the interfaces ..... | 8 | +| 7 General approach ..... | 8 | +| 7.1 Interference mitigation mechanism ..... | 8 | +| 7.2 Device discovery ..... | 12 | +| 7.3 Device measurement ..... | 16 | +| 7.4 Device configuration ..... | 17 | +| 7.5 Primitives supporting coexistence protocol..... | 19 | +| 7.6 Description of primitives ..... | 20 | +| Annex A – Transmission formats for message exchange ..... | 36 | +| A.1 Transmission formats ..... | 36 | +| Bibliography..... | 39 | + + + +# Mitigation of interference between DSL and PLC + +# 1 Scope + +This Recommendation specifies functionality of a mechanism to mitigate interference caused by in-home powerline communication (PLC) devices to an x-type digital subscriber line (xDSL) network termination (implementing transceivers in compliance with ITU-T Recommendations such as [[ITU-T G.993.2](#)] and [[ITU-T G.9701](#)]). This Recommendation addresses various in-home network types and wiring topologies. + +The coordination of both the xDSL access network and in-home PLC network is facilitated by an arbitration function (AF), in order to reduce interference and optimize the performance of both networks and meet the throughput requirements to the end customer across both networks, by appropriately configuring relevant parameters of PLC devices and xDSL network termination (NT) based on a coordination policy that is usually determined and provided by the operator. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [[ITU-T G.993.2](#)] Recommendation ITU-T G.993.2 (2015), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [[ITU-T G.994.1](#)] Recommendation ITU-T G.994.1 (2012), *Handshake procedures for digital subscriber line transceivers*. +- [[ITU-T G.997.1](#)] Recommendation ITU-T G.997.1 (2012), *Physical layer management for digital subscriber line transceivers*. +- [[ITU-T G.997.2](#)] Recommendation ITU-T G.997.2 (2015), *Physical layer management for G.fast transceivers*. +- [[ITU-T G.998.4](#)] Recommendation ITU-T G.998.4 (2015), *Improved impulse noise protection for digital subscriber line (DSL) transceivers*. +- [[ITU-T G.9701](#)] Recommendation ITU-T G.9701 (2014), *Fast access to subscriber terminals (G.fast) – Physical layer specification*. +- [[ITU-T G.9961](#)] Recommendation ITU-T G.9961 (2015), *Unified high-speed wireline-based home networking transceivers – Data link layer specification*. +- [[ITU-T G.9962](#)] Recommendation ITU-T G.9962 (2014), *Unified high-speed wire-line based home networking transceivers – Management specification*. +- [[ITU-T G.9979](#)] Recommendation ITU-T G.9979 (2014), *Implementation of the generic mechanism in the IEEE 1905.1a-2014 Standard to include applicable ITU-T Recommendations*. + +- [IEEE 802.3] IEEE Std 802.3-2008, *IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks--Specific requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications.* +- [IEEE 1905.1] IEEE Std 1905.1-2013, *IEEE Standard for a Convergent Digital Home Network for Heterogeneous Technologies.* +- [IEEE 1905.1a] IEEE Std 1905.1a-2014, *IEEE Standard for a Convergent Digital Home Network for Heterogeneous Technologies, Amendment 1, Support of New MAC/PHYs and Enhancements.* + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 arbitration function (AF):** Entity that facilitates coordination between the xDSL and PLC systems in order to reduce interference on the basis of coordination policy, by appropriately configuring parameters of the xDSL and PLC devices. The coordination policy is expected to be determined and provided by the operator. In the case where such a policy is not determined or provided by the operator, the AF works according to a predefined default policy. + +**3.2.2 centralized control mode (CCM):** A mode of a PLC network in which devices do not exchange information directly with the AF but via the PLC-NC. + +**3.2.3 distributed control mode (DCM):** A mode of a PLC network in which PLC devices exchange information directly with the AF. + +**3.2.4 IEEE 1905:** Devices implementing the abstraction layer specified in [IEEE 1905.1] and [IEEE 1905.1a]. In this Recommendation, the term IEEE 1905 is used to refer to the technology, the term IEEE 1905.1 is used to refer to the base standard [IEEE 1905.1] and the term [IEEE 1905.1a] is used to refer to the Amendment [IEEE 1905.1a]. + +**3.2.5 power line communication (PLC) devices:** Components of a PLC network that are intended to be connected to each other via power line and that communicate with each other using appropriate coding and modulation methods. + +**3.2.6 PLC network:** A set of interconnected PLC devices that communicate with each other. The in-home PLC network uses in-home power line wiring as the transmission medium. + +**3.2.7 PLC network controller (PLC-NC):** In CCM, one of the PLC devices in the PLC network that is assigned to control all other devices in the network. + +**3.2.8 xDSL access network:** A network that comprises customer premises equipment and the exchange (or cabinet or DP) equipment implementing xDSL functionality that is compliant with at least one of the ITU-T Recommendations of the ITU-T G.99x or ITU-T G.970x-series. + +**3.2.9 xDSL network termination (NT):** A customer premises equipment implementing xDSL transceiver and associated functionality that is compliant with at least one of the ITU-T Recommendations of the ITU-T G.99x or ITU-T G.970x-series. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|---------|-----------------------------------------------------| +| ACS | Auto-Configuration Server | +| AF | Arbitration Function | +| AL | Abstraction Layer | +| CCM | Centralized Control Mode | +| CMDU | Control Message Data Unit | +| CO | Central Office | +| CO-MIB | Central Office-Management Information Base | +| CPE | Customer Premises Equipment | +| CWMP | CPE WAN Management Protocol | +| DCM | Distributed Control Mode | +| DLL | Data Link Layer | +| DP | Distribution Point | +| DPU-MIB | Distribution Point Unit Management Information Base | +| DPM | xDSL and PLC interference Mitigation | +| DPU | Distribution Point Unit | +| EMS | Element Management System | +| LAN | Local Area Network | +| MAC | Media Access Control | +| ME | Management Entity | +| NMS | Network Management System | +| NT | Network Termination | +| OLR | On-line Reconfiguration | +| PHY | Physical Layer | +| PLC | Powerline Communication | +| PLC-NC | PLC Network Controller | +| PSD | Power Spectral Density | +| QLN | Quiet Line Noise | +| QoS | Quality of Service | +| RGW | Residential Gateway | +| SAVN | Showtime-Adaptive Virtual Noise | +| SNR | Signal-to-Noise Ratio | +| SNRM | Signal-to-Noise Ratio Margin | +| TLV | Type, Length and Value | +| WAN | Wide Area Network | +| xDSL | x-type Digital Subscriber Line | + +# 5 Conventions + +None. + +# 6 Reference models + +## 6.1 Generalized reference model + +The generalized reference model addressing the interference mitigation mechanism is presented in Figure 6-1. The arbitration function (AF) facilitates resource allocation between the powerline communication (PLC) network and the xDSL NT. The communication between the PLC and the AF are defined over logical interfaces $\Phi_P$ and $\Phi_C$ , respectively, while the operator may control the AF via the logical interface $\Phi_A$ . The operator's control on AF, as well as other elements of the customer premises network, is usually implemented via the network management system (NMS). In the case where operator control of the AF is not established for any reason, the AF may use its internal arbitration and coexistence policies to facilitate xDSL-PLC coordination (e.g., the default policies or those downloaded during previous session). This includes the following cases: + +- xDSL line is inactive and thus no connection to the NMS is available; +- xDSL line is active, but no connection to the NMS is established or NMS is unavailable. + +In these cases the AF should be able to function without operator control. + +NOTE – To support the coexistence mechanism during the time when operator control is not available, the AF may (either partially or entirely) reside inside the residential gateway (RGW). + +![Figure 6-1: Generalized reference model diagram](54fabc351eda5228d2fa28cd9ba07971_img.jpg) + +The diagram illustrates the generalized reference model. At the top is a box labeled 'NMS'. A vertical line descends from the NMS to a central box labeled 'Arbitration function (AF)'. This line is labeled with a red dashed line and the symbol $\Phi_A$ . From the bottom of the 'Arbitration function (AF)' box, two vertical lines descend to two separate boxes at the bottom: 'xDSL NT' on the left and 'PLC network' on the right. The line to the 'xDSL NT' is labeled with a red dashed line and the symbol $\Phi_C$ . The line to the 'PLC network' is labeled with a red dashed line and the symbol $\Phi_P$ . Below the diagram, the text 'G.9977(16)\_F6-1' is present. + +Figure 6-1: Generalized reference model diagram + +**Figure 6-1 – Generalized reference model** + +An application of the generalized reference model showing more details of the xDSL and the PLC network is presented in Figure 6-2. + +![Figure 6-2: An application of the generalized reference model. The diagram shows an NMS connected to an AF. The AF is connected to an xDSL network and an N-node PLC network. The xDSL network contains a DSLAM/DPU and an NT. The N-node PLC network contains Node 1 and Node N. Various interfaces are labeled with Φ_A, Φ_C, and Φ_P.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +The diagram illustrates the generalized reference model. At the top left, an NMS is connected to an AF via a red double-headed arrow labeled $\Phi_A$ . The AF is connected to two network blocks. The first block, labeled 'xDSL network', contains a 'DSLAM/DPU' and an 'NT'. The 'DSLAM/DPU' contains a 'PHY' and an 'xTU-O' connected to an 'ME'. The 'NT' contains an 'xTU-R' connected to a 'PHY' and an 'ME'. A red arrow labeled $\Phi_C$ points from the AF to the 'xTU-O' in the 'DSLAM/DPU'. The 'xDSL network' is connected to the second block, labeled 'N-node PLC network', via a 'T/S' interface. The 'N-node PLC network' contains 'Node 1' and 'Node N'. 'Node 1' contains a 'PHY', a 'DLL', and an 'ME'. 'Node N' contains an 'ME', a 'DLL', and a 'PHY'. A red arrow labeled $\Phi_P$ points from the AF to the 'PHY' in 'Node 1'. + +Figure 6-2: An application of the generalized reference model. The diagram shows an NMS connected to an AF. The AF is connected to an xDSL network and an N-node PLC network. The xDSL network contains a DSLAM/DPU and an NT. The N-node PLC network contains Node 1 and Node N. Various interfaces are labeled with Φ\_A, Φ\_C, and Φ\_P. + +**Figure 6-2 – An application of the generalized reference model** + +The first example of a system functional model corresponding to the reference models in Figure 6-1 and Figure 6-2 is presented in Figure 6-3. It represents the case in which the AF resides entirely in the RGW. To address a generic case of user installation, both the PLC network and the xDSL NT are connected to the RGW using 802.3 local area network (LAN) interfaces (RGW is a stand-alone device that incorporates AF). + +![Figure 6-3: An example of a system functional model for the case when the xDSL access network and PLC network are associated with the same operator network (AF resides inside the RGW). The diagram shows an NMS connected to an Exchange/cabinet/DP. The Exchange/cabinet/DP contains a DSLAM/DPU with two xTU-O units. One xTU-O is connected to an RGW via a red dashed line labeled Φ_A. The other xTU-O is connected to a Copper line, which leads to an NT containing an xTU-R. The RGW contains an AF and two 802.3 interfaces. One 802.3 interface is connected to the NT, and the other is connected to a PLC device. The PLC device is connected to a User. Two other Users are also connected to PLC devices, which are connected to the same PLC network.](5a4e62bead259c258d069fd3663ea670_img.jpg) + +The diagram shows a system functional model where the AF is inside the RGW. An NMS is connected to an 'Exchange/cabinet/DP'. Inside the 'Exchange/cabinet/DP' is a 'DSLAM/DPU' with two 'xTU-O' units. A red dashed line labeled $\Phi_A$ connects the 'Exchange/cabinet/DP' to the 'AF' inside the 'RGW'. A 'Copper' line connects one 'xTU-O' to an 'NT' containing an 'xTU-R'. The 'RGW' contains an 'AF' and two '802.3' interfaces. One '802.3' interface is connected to the 'NT', and the other is connected to a 'PLC device'. The 'PLC device' is connected to a 'User'. Two other 'Users' are also connected to 'PLC devices', which are connected to the same PLC network. Red dashed lines labeled $\Phi_C$ and $\Phi_P$ connect the 'AF' to the '802.3' interfaces in the 'RGW'. + +Figure 6-3: An example of a system functional model for the case when the xDSL access network and PLC network are associated with the same operator network (AF resides inside the RGW). The diagram shows an NMS connected to an Exchange/cabinet/DP. The Exchange/cabinet/DP contains a DSLAM/DPU with two xTU-O units. One xTU-O is connected to an RGW via a red dashed line labeled Φ\_A. The other xTU-O is connected to a Copper line, which leads to an NT containing an xTU-R. The RGW contains an AF and two 802.3 interfaces. One 802.3 interface is connected to the NT, and the other is connected to a PLC device. The PLC device is connected to a User. Two other Users are also connected to PLC devices, which are connected to the same PLC network. + +**Figure 6-3 – An example of a system functional model for the case when the xDSL access network and PLC network are associated with the same operator network (AF resides inside the RGW)** + +A second example of a system functional model corresponding to the reference models in Figure 6-1 and Figure 6-2 is presented in Figure 6-4. It represents the case in which the AF resides entirely in the RGW and a PLC device is also part of the RGW. The xDSL NT is connected to the RGW using 802.3 LAN interfaces. + +![Figure 6-4: System functional model for xDSL access and PLC network associated with the same operator network (AF and a PLC device reside inside the RGW).](d4af765160d04ecef538e5066006dc77_img.jpg) + +This diagram shows the functional model where the AF and a PLC device are inside the RGW. On the left, an NMS connects via a dashed red line to an Exchange/cabinet/DP containing a DSLAM/DPU with two xTU-O units. A dashed red line labeled $\Phi_A$ crosses into the Customer premises to an RGW. Inside the RGW, an AF unit connects via dashed red lines labeled $\Phi_C$ and $\Phi_P$ to an 802.3 interface and a PLC device respectively. The 802.3 interface connects to an xTU-R within an NT block. A solid line labeled 'Copper' connects an xTU-O to the xTU-R. The PLC device in the RGW connects to a common bus in the customer premises, which links to two User blocks and two additional PLC devices, each with an 802.3 interface. The diagram is indexed G.9977(16)\_F6-4. + +Figure 6-4: System functional model for xDSL access and PLC network associated with the same operator network (AF and a PLC device reside inside the RGW). + +**Figure 6-4 – An example of a system functional model for the case when the xDSL access network and PLC network are associated with the same operator network (AF and a PLC device reside inside the RGW)** + +A third example of a system functional model corresponding to the reference models in Figure 6-1 and Figure 6-2 is presented in Figure 6-5. It represents the case in which the AF resides entirely in the RGW and the xDSL NT is also part of the RGW. The PLC network is connected to the RGW using 802.3 LAN interfaces. In this case, the NT functionalities are integrated into the RGW. + +![Figure 6-5: System functional model for xDSL access and PLC network associated with the same operator network (AF and xDSL NT reside inside the RGW).](27b06ec9f42b5d727a2630f61a5f1861_img.jpg) + +This diagram shows the functional model where the AF and xDSL NT are inside the RGW. The left side (NMS and Exchange/cabinet/DP) is identical to Figure 6-4. The dashed red line $\Phi_A$ enters the RGW. Inside the RGW, the AF connects via $\Phi_C$ to an NT block and via $\Phi_P$ to an 802.3 interface. The NT block is connected to the xTU-O via a 'Copper' line. Both the NT and the 802.3 interface inside the RGW connect to a bus. This bus connects to two User blocks and three PLC devices, each with its own 802.3 interface. The diagram is indexed G.9977(16)\_F6-5. + +Figure 6-5: System functional model for xDSL access and PLC network associated with the same operator network (AF and xDSL NT reside inside the RGW). + +**Figure 6-5 – An example of a system functional model for the case when the xDSL access network and PLC network are associated with the same operator network (AF and xDSL NT reside inside the RGW)** + +A fourth example is the case in which both the xDSL NT and PLC device are implemented as a part of the RGW is presented in Figure 6-6. In this case, the xDSL NT functionalities are integrated into the RGW. + +![Figure 6-6: System functional model for xDSL access network and PLC network associated with the same operator network. The diagram shows an Exchange/cabinet/DP containing an NMS, DSLAM/DPU, and two xTU-O units. A copper line connects the xTU-O units to an RGW in the Customer premises. The RGW contains an AF, NT, and PLC device. Two Users are connected to the PLC device via 802.3 interfaces. Interfaces are labeled ΦA, ΦC, and ΦP.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +G.997(16)\_F6-6 + +Figure 6-6: System functional model for xDSL access network and PLC network associated with the same operator network. The diagram shows an Exchange/cabinet/DP containing an NMS, DSLAM/DPU, and two xTU-O units. A copper line connects the xTU-O units to an RGW in the Customer premises. The RGW contains an AF, NT, and PLC device. Two Users are connected to the PLC device via 802.3 interfaces. Interfaces are labeled ΦA, ΦC, and ΦP. + +**Figure 6-6 – An example of a system functional model for the case when the xDSL access network and PLC network are associated with the same operator network (AF, xDSL NT and a PLC device reside inside the RGW)** + +A fifth example of a system functional model corresponding to the reference models in Figure 6-1 and Figure 6-2 is presented in Figure 6-7. It represents the case in which the AF resides in the broadband network, remote from the customer premises. The AF implementation may be virtualized, hosted in the cloud, be a part of NMS or element management system (EMS) functionality, etc. + +NOTE – A network-located AF may use [\[ITU-T G.997.1\]](#) and [\[ITU-T G.997.2\]](#) for much of the functionality of the $\Phi_C$ interface, and may use CPE WAN management protocol (CWMP) [b-BBF TR-069], [b-BBF TR-181] for much of the functionality of the $\Phi_P$ interface. For example, for xDSL, SNR(f) may be read across the network using [\[ITU-T G.997.1\]](#) and [\[ITU-T G.997.2\]](#) and the PLC PSD shaping mask (PSM) [\[ITU-T G.9961\]](#) may be configured across the network using CWMP. + +![Figure 6-7: System functional model for the case when the AF is located in the broadband network. The diagram shows a Network location containing an NMS, AF, and TR-069 ACS. The AF is connected to an xDSL network (containing DSLAM/DPU and NT) and an N-node PLC network (containing Node 1 to Node N) via TR-069 interfaces. The xDSL network is connected to a V source. The PLC network nodes contain PHY, DLL, and ME components. Interfaces are labeled ΦA, ΦP, ΦC, and ΦC over TR-069.](cab0834804fb031b43865554cc8d06ab_img.jpg) + +G.997(16)\_F6-7 + +Figure 6-7: System functional model for the case when the AF is located in the broadband network. The diagram shows a Network location containing an NMS, AF, and TR-069 ACS. The AF is connected to an xDSL network (containing DSLAM/DPU and NT) and an N-node PLC network (containing Node 1 to Node N) via TR-069 interfaces. The xDSL network is connected to a V source. The PLC network nodes contain PHY, DLL, and ME components. Interfaces are labeled ΦA, ΦP, ΦC, and ΦC over TR-069. + +**Figure 6-7 – An example of a system functional model for the case when the AF is located in the broadband network** + +In Figure 6-7 the AF communicates to the xDSL NT and the PLC devices using the TR-069 protocol [b-BBF TR-069]. This is possible when both the xDSL NT and the PLC device(s) support TR-069. + +In the distributed mode all the PLC devices need to support TR-069 in this example. In the centralized mode, at least one PLC device needs to support TR-069 [[ITU-T G.9962](#)]. + +The TR-069 protocol is defined such that customer premises equipment (CPE) (i.e., xDSL NT, RGW and PLC devices) communicates with an auto-configuration server (ACS) using corresponding data models [b-BBF TR-181]. The ACS encapsulates AF primitives passed across the $\Phi_P$ and $\Phi_C$ interfaces, respectively, into corresponding TR-069 data models and passes them transparently, so that the primitives sent from the AF to the ACS are passed to the xDSL NT and the PLC devices, and the primitives sent from the xDSL NT and the PLC devices are passed from the ACS to the AF. In the case where TR-069 connectivity is lost (e.g., due to loss of broadband connectivity), a local AF using a predefined default policy should be invoked. The network-located AF and the ACS could be part of the same system. + +## 6.2 Details of the interfaces + +The defined interfaces of the generalized reference model ( $\Phi_C$ , $\Phi_P$ , and $\Phi_A$ , Figure 6-1) are logical, which means: + +- the interface is defined by sets of primitives to be exchanged (see clause 7.5); +- no L1-layer protocol (physical signals) is specified. + +The $\Phi_C$ , $\Phi_P$ , and $\Phi_A$ interface primitives are exchanged by using protocols specified in this Recommendation and messages with transmission formats defined in Annex A. + +# 7 General approach + +## 7.1 Interference mitigation mechanism + +### 7.1.1 Overview + +The coexistence mechanism defined in this Recommendation provides mitigation of the PLC interference into xDSL line and mutual optimization of the performance of the xDSL line and PLC network. It facilitates normal initialization and stable steady-state operation of a xDSL line within the quality of service (QoS) requirements defined by the operator, in the presence of PLC and endeavours to provide minimal performance degradation for PLC devices and seamless PLC operation (i.e., no service disruption during xDSL initialization). + +The mitigation of PLC interference is accomplished by an AF implementing the following AF device discovery, AF coordination, and AF policy functionalities: + +AF device discovery functionality includes the following: + +- discovery of the media access control (MAC) addresses of the xDSL NT and PLC devices; +- identification of the type and status of each device; +- monitoring of device presence and status changes. + +AF coordination functionality includes the following: + +- establish communication with PLC devices and xDSL NT; +- coordinate interference measurement, i.e., trigger measurement modes and retrieve results; +- collect interference data and report it to the AF; +- coordinate start-up procedure of xDSL and PLC devices; +- coordinate parameter reconfiguration of PLC devices and xDSL to mitigate interference based on AF policy. + +AF policy functionality includes the following: The AF implements a provided coordination policy from an operator. In the case where such a policy is not provided or available the AF works according + +to a predefined (default) policy. The coordination policy may be provided via a static definition (e.g., autonomously implemented within the unit embedding the AF) or via a dynamic definition using a remote management protocol (e.g., [b-BBF TR-069]). + +Operator control of the AF and the applied coexistence policies prevent conflicting goals that PLC devices and xDSL NT may have, while the overall goal is to optimize the overall performance. + +The coexistence mechanism defined in this Recommendation facilitates operation for the following cases: + +- when xDSL line is inactive – the PLC devices should be allowed to use all network resources; +- when xDSL line starts initialization – the PLC network and/or devices should facilitate xDSL initialization such that the QoS targets defined by the operator are achieved at the transition to showtime; +- when xDSL line is active – the xDSL line in showtime should maintain the QoS targets set by the operator and should not be disrupted by reconfiguration of the PLC network (e.g., when new PLC devices are added to the network or PLC devices are moved to another location). + +### 7.1.2 Scenarios + +This clause provides an overview of the operation of the xDSL access system and PLC network under different coexistence scenarios. The details of the mechanisms that are used are explained in clauses 7.2, 7.3 and 7.4. + +#### 7.1.2.1 Scenario #1: PLC is active while xDSL is OFF + +In this scenario no broadband service and no management from the operator is available. The PLC network is standalone, operates autonomously and no additional limits on transmit power spectral density (PSD) or other parameters of PLC devices related to coexistence apply. + +In order to monitor the status of the PLC network and xDSL NT, the AF shall poll those from time to time using STATUS.request primitives over $\Phi_P$ and $\Phi_C$ interfaces, respectively (see clause 7.3). The xDSL NT and the applicable PLC devices shall reply with STATUS.confirm primitives, respectively, indicating status updates whenever polled by the AF. If the STATUS.confirm primitives from the xDSL NT are not received, the AF shall monitor discovery messages from the xDSL NT to detect when it turns on. + +#### 7.1.2.2 Scenario #2: xDSL line turns active in presence of an active PLC network + +NOTE 1 – During initialization, the xDSL NT exchanges special training signals with its peer installed at an exchange, a cabinet, or a distribution point (DP). The xDSL NT is effectively disconnected from the exchange, cabinet, or DP; no broadband service and no management communications are available. In this state the AF can set parameters of the PLC network so that the necessary conditions for the xDSL line to initialize with QoS parameters required by the operator for broadband connection (based on SLA agreement with the customer) are facilitated. At the end of the initialization xDSL line transitions to showtime, allowing the operator to deliver broadband services and remotely manage the RGW, the AF and the PLC network. + +The xDSL NT indicates to the AF that it starts initialization by sending a STATUS.ind primitive or indicating start of initialization in STATUS.confirm primitive after receiving a STATUS.request primitive from the AF across $\Phi_C$ interface. + +Upon reception of the xDSL NT indication of initialization, the AF may send to the PLC network a CONFIGURE.request defining a reduced PSD setting if it expects possible initialization issues, setting the PLC devices in a state in which they do not disturb the initialization process. Upon reception of a CONFIGURE.request primitive, the PLC network shall reply to the AF by sending a primitive CONFIGURE.confirm, which confirms that the requested PSD is applied to all relevant PLC devices. + +NOTE 2 – This does not imply that the transmit PSD of all PLC devices have to be reduced from the nominal PSD levels inside the frequency bands assigned for the xDSL downstream transmission. Only those PLC devices that are identified by the AF as potential cause of xDSL NT initialization failure (e.g., newly installed devices or re-positioned devices, or those devices whose PSD was reduced during the previous xDSL session) may be requested to reduce their transmit PSD by an AF-determined value. + +Upon reception of CONFIGURE.confirm primitive from the PLC, the AF may send to the xDSL NT a CONFIGURE.request primitive indicating that the xDSL NT may safely start the initialization (including its noise-sensitive part). The xDSL NT shall reply to the AF by sending the CONFIGURE.confirm primitive that acknowledges the request from the AF. After the xDSL line completes the initialization, it transitions to showtime. + +NOTE 3 – The ITU-T G.994.1 handshake is robust enough to handle interference from a PLC with nominal transmit PSD levels. Therefore, the xDSL NT may start the ITU-T G.994.1 handshake before it receives a confirmation that PLC applied the reduced PSD limits. + +NOTE 4 – If the AF over-restricts the PSD of the PLC devices during xDSL initialization, the xDSL line may initialize with transmission parameters that are established for the case of very low noise interference, which is obviously suboptimal. In addition, some PLC devices may perform insufficiently. + +#### 7.1.2.3 Scenario #3: Steady-state operation of xDSL in the presence of a PLC network + +After xDSL NT completes initialization and reaches showtime, the broadband link is established and all operators' external management tools (NMS and potentially others) become available to control the AF. Now the AF, possibly under control of the operator, shall coordinate operation of both the xDSL and the PLC and can maximize the overall performance of the customer connection, using AF arbitration policies established by the operator. The measurements of interference between the PLC and the xDSL line is run for all relevant PLC devices to optimize their transmit PSDs, as specified in clause 7.3. Per results of the measurements, the AF reconfigures the PLC devices and the xDSL line parameters with the aim of optimizing performance by minimizing the surplus signal-to-noise ratio (SNR) margin, thereby allowing higher transmit PSDs for some of the PLC devices. + +An example of a timeline showing initialization, transition to showtime and operation during showtime is presented in Figure 7-1. + +![Figure 7-1: Example of a timeline for xDSL operation in presence of PLC. The diagram shows the interaction between a PLC network and an xDSL NT over time. The PLC network starts in a mode that protects xDSL initialization. The xDSL NT goes through initialization and then showtime. During showtime, the AF starts measurements (sensitivity check) for PLC devices. CPE reports are sent to the AF for SNR DS 1, SNR DS 2, SNR DS (K-1), and SNR DS K (end of the check). The AF communicates to the xDSL NT the expected noise level from the PLC network and to the PLC network the suggested PSD in xDSL DS bands. The PLC network adjusts its devices, and the xDSL NT performs new bit loading.](cb4cfa42ce34febde7bdb882f3fc3094_img.jpg) + +The diagram illustrates the timeline for xDSL operation in the presence of a PLC network. The horizontal axis represents time, and the vertical axis distinguishes between the PLC network and the xDSL NT. The sequence of events is as follows: + +- PLC network:** Works in mode that protects xDSL initialization. It receives a request to protect DSL initialization and later communicates the expected noise level from the PLC network to the xDSL NT. Finally, it receives suggested PSD in xDSL DS bands and adjusts its devices. +- xDSL NT:** Undergoes Initialization, then transitions to Showtime. It sends STATUS primitives to the AF. It receives measurements (sensitivity check) from the AF, CPE reports for SNR DS 1, SNR DS 2, SNR DS (K-1), and SNR DS K (end of the check). It also receives the expected noise level from the PLC network and performs new bit loading. +- AF (Access Frequency):** Starts the measurements (sensitivity check) during showtime. It receives CPE reports and communicates the expected noise level to the xDSL NT and the suggested PSD to the PLC network. +- CPE Reports:** CPE reports are sent to the AF for SNR DS 1, SNR DS 2, SNR DS (K-1), and SNR DS K (end of the check). +- Measurements:** A "Measurement (sensitivity test)" period is shown, covering measurements for PLC device #1, #2, ..., #K in xDSL DS bands. + +G.997(16)\_F7-1 + +Figure 7-1: Example of a timeline for xDSL operation in presence of PLC. The diagram shows the interaction between a PLC network and an xDSL NT over time. The PLC network starts in a mode that protects xDSL initialization. The xDSL NT goes through initialization and then showtime. During showtime, the AF starts measurements (sensitivity check) for PLC devices. CPE reports are sent to the AF for SNR DS 1, SNR DS 2, SNR DS (K-1), and SNR DS K (end of the check). The AF communicates to the xDSL NT the expected noise level from the PLC network and to the PLC network the suggested PSD in xDSL DS bands. The PLC network adjusts its devices, and the xDSL NT performs new bit loading. + +Figure 7-1 – Example of a timeline for xDSL operation in presence of PLC + +The xDSL NT indicates transition into showtime to the AF by sending STATUS.ind primitive or by indicating transition into showtime in STATUS.confirm primitive across $\Phi_C$ interface. Upon reception of the corresponding STATUS.ind primitive from the xDSL NT, the AF may start the interference measurements between the PLC and the xDSL NT. Further, interference measurements between the PLC and the xDSL NT can be routinely performed during the xDSL NT showtime as specified in clause 7.3. + +For a measurement of the impact of PLC device(s) into xDSL, the AF sends a MEASURE-MODE.request primitive indicating that the particular PLC device(s) needs to be measured. The PLC device in distributed control mode (DCM) or the PLC network controller (PLC-NC) in centralized control mode (CCM) replies by a MEASURE-MODE.confirm primitive indicating the availability of the device(s) to be measured. In the case of a positive reply, the requested PLC device starts transmission associated with the measurement with the delay indicated in the MEASURE-MODE.confirm response (see clause 7.3.2). In the case of a negative reply, the AF may retransmit the request. + +NOTE 1 – Messages conveying primitives can be sent directly to the PLC device in DCM or to the PLC-NC in CCM. They may also be relayed via other PLC device(s) in the network. + +Upon a positive reply from the PLC device, the AF informs the xDSL NT of the measurement by sending the MEASURE.request primitive to the xDSL NT. The xDSL NT replies by sending a MEASURE.confirm primitive and starts the measurement procedure by measuring the SNR (quiet line noise (QLN)) at the receiver. + +In order to obtain the measurement result, the AF sends the xDSL NT a RESULTS.request primitive. The xDSL NT replies by sending a RESULTS.confirm primitive that contains the results of the measurement primitive. + +After AF obtains the measurement result, the AF may send another MEASURE.request primitive to the xDSL NT to perform another measurement. The total number of measurements in the set depends on the PLC topology and the xDSL type and is determined by the AF. Once sufficient measurement data is obtained from the xDSL NT, the AF requests the PLC device to complete the measurement (see clause 7.3.2). + +After one or more measurements the AF may reconfigure the PLC and/or the xDSL NT according to the measurement results. For this, the AF sends to the xDSL NT, or to PLC, or to both, a CONFIGURE.request primitive. The responding entity (xDSL NT or PLC or both) replies by CONFIGURE.confirm primitive and implements the requested re-configuration. + +NOTE 2 – The noise generated by the PLC is non-stationary by nature because any particular PLC device may start and stop transmitting at times that are not predictable for the xDSL NT; furthermore, different PLC devices create different interference into the xDSL NT. To mitigate the performance instability caused by non-stationary noise, xDSL NT should apply a substantial SNR margin (SNRM), or showtime-adaptive virtual noise (SAVN), or similar protection methods. + +#### **7.1.2.4 Scenario #4: PLC devices initializing in presence of an active xDSL network** + +The procedures described in scenario #3 allow configuration of the PLC devices and the xDSL line so that the throughput of the overall path is maximized based on operator policies. These policies may lead to a reduced PSD mask applied to some of the PLC devices and/or additional constraints to the xDSL NT. + +During the steady-operation of the xDSL line, the topology of the PLC network may change due to new devices being incorporated into the PLC network or existing PLC devices moved from one connection point to another one. + +The AF may configure a "default PSD mask" to be applied to these PLC devices, for which a measurement process has not been possible yet using the CONFIGURE.request primitive. + +In DCM, this "default PSD mask", if configured, shall be applied to each new PLC device for which interference is expected to be excessive (e.g., in the case where some other PLC devices of the network have been identified by the AF as potential sources of interference and a PSD limitation has been set). Upon reception of a CONFIGURE.request primitive requesting to set a "default PSD mask", the PLC device shall respond with a CONFIGURE.confirm primitive. + +In CCM, this "default PSD mask", if configured, shall be applied by the PLC-NC to new PLC devices for which interference is expected to be excessive. Upon reception of a CONFIGURE.request + +primitive requesting to set a "default PSD mask", the PLC-NC shall respond with a CONFIGURE.confirm primitive. Furthermore, the PLC-NC provides configuration of all other PLC devices and responds to the AF, accordingly (see clause 7.4.2). + +During short transient periods (e.g., device registration) new devices may use the PSD allowed by the regional regulation, even in the case where PLC interference is expected. This is tolerable providing that this behaviour lasts for less than 100 ms. + +Whenever a new device is admitted to a PLC network, it shall announce its presence to the AF. + +Upon discovering a new node in the PLC network, the AF, as described in scenario #2, may send to the PLC network a CONFIGURE.request primitive defining a reduced PSD for the newly joined device if it expects possible interference issues, setting the PLC device parameters so that it mitigates the disturbance to the xDSL link. Prior to that, the new device shall refrain from transmission, if possible, to eliminate potential interference. Furthermore, the AF may launch a measurement procedure for the new device. The results of the measurement procedure may lead to a reconfiguration of the xDSL line and the PLC device as described in scenario #3. + +## 7.2 Device discovery + +### 7.2.1 Overview + +The discovery mechanism provides the AF, the xDSL NT and the PLC devices with a procedure to announce themselves and become aware of the existence of devices that are relevant for the coexistence procedure. The discovery mechanism provides the tools that: + +- allow the xDSL NT and PLC network devices to announce their presence, address and main properties; +- allow the xDSL NT and PLC network devices to discover the AF; +- allow the AF to routinely monitor the status of the devices relevant for the interference mitigation procedure; +- allow the AF to be informed of new devices added to or leaving the PLC network. + +The specified discovery mechanism addresses the operation of the PLC networks in both DCM and CCM. + +### 7.2.2 Discovery of PLC devices + +In case of DCM, the PLC devices shall broadcast a topology discovery message to indicate their presence at power on, upon transitions in the network topology and at least every 60 seconds, as defined in clause 8.2.1.1 of [IEEE 1905.1]. This allows the AF to discover PLC devices immediately upon power on or upon transitions in the network topology and monitor their presence in the network. + +In case of CCM, the PLC-NC shall broadcast a topology discovery message to indicate its presence once it is active, upon transitions in the network topology and at least every 60 seconds, as defined in clause 8.2.1.1 of [IEEE 1905.1]. This allows the AF to discover the PLC-NC once it is active and other PLC devices once they register with the PLC-NC or upon transitions in the network topology and monitor their presence in the network. + +PLC devices incorporating an IEEE 1901 interface for PLC are discovered via IEEE 1905 device information type known as type, length and value (TLV) contained in the topology discovery message, as defined in clause 6.4.5 of [IEEE 1905.1]. PLC devices incorporating any PLC interface not listed in Table 6-12 of [IEEE 1905.1] (e.g., ITU-T G.996x (G.hn) and Homeplug AV2) are discovered by the AF using IEEE 1905.1a generic physical layer (PHY) query/response procedure (see clause 8.2.3 of [IEEE 1905.1a]). In this latter case, the PLC interface is discovered via the generic PHY device information type TLV conveyed in the generic PHY response message received by the AF. + +During the discovery procedure, PLC devices indicate whether IEEE 1905 is fully supported or not via DPM device identification (DPM-ID) TLV (see clause 7.2.5). + +#### 7.2.2.1 Exchange of status information + +Upon reception of a broadcasted STATUS.request primitive, a PLC device shall reply to the AF with a STATUS.confirm primitive across the $\Phi_P$ interface, as defined in clause 7.6.5. If the PLC network operates in CCM, only the PLC-NC shall reply. + +Whenever the status of a PLC device changes, this device shall inform the AF by sending the STATUS.ind primitive, as defined in clause 7.6.6. If the PLC network operates in CCM, only the PLC-NC shall send to the AF a STATUS.ind primitive on a new device joining or on a departing device, indicating devices that are currently part of the network and those that have been added to the network since the last status report. + +Additionally, a device may indicate to the AF the suitability of starting a measurement process through the STATUS change type field of STATUS.ind primitive. + +An AF may routinely request for update of the status of a PLC device by sending a STATUS.request primitive over the $\Phi_P$ interface, as defined in clause 7.6.4. Upon reception of a STATUS.request primitive, each PLC device shall respond with a STATUS.confirm primitive defined in clause 7.6.5, containing the required information (if the PLC network operates in CCM, only the PLC-NC reports the status of the entire network). + +NOTE – PLC devices departing from the network operating in DCM may be identified by the absence of the STATUS.confirm response from the device. + +### 7.2.3 Discovery of xDSL devices + +The xDSL NT shall include at least the following IEEE 1905 discovery functionality: + +- support of topology discovery message (clauses 6.3.1 and 8.2.1.1 of [IEEE 1905.1], with the value of the abstraction layer (AL) MAC address set equal to the xDSL NT MAC address if no separate AL MAC address is established); +- support of topology query messages (clauses 6.3.2 and 8.2.2.1 of [IEEE 1905.1]); +- support of topology response message (clauses 6.3.3 and 8.2.2.2 of [IEEE 1905.1], with indication of 0 bridging capabilities, 0 neighbour device TLVs; it shall use PowerOff TLV to indicate the power state of the xDSL interface). + +NOTE – The list above defines the minimum required IEEE 1905 capabilities. If an xDSL NT implementation fully supports IEEE 1905, other relevant capabilities may be implemented as well. + +If the xDSL NT indicates support of [IEEE 1905] in the topology discovery message and topology response message (see clause 7.2.5), the xDSL interface will be identified via generic PHY query/response messages and generic PHY device information type TLV defined in clause 8.2.3 of [IEEE 1905.1a] and otherwise, the xDSL NT properties will be discovered during the exchange of status information defined in clause 7.2.3.1. The generic PHY XML description document (clause 8.4 of [IEEE 1905.1a]) for xDSL interfaces is defined in clauses 7 and 8 of [[ITU-T G.9979](#)]. + +#### 7.2.3.1 Exchange of status information + +Upon reception of a broadcasted STATUS.request primitive, the xDSL NT shall reply to the AF with a STATUS.confirm primitive across the $\Phi_C$ interface, as defined in clause 7.6.2. + +Whenever status of the xDSL NT has changed, it shall inform the AF on the new status by sending a STATUS.ind primitive, as described in clause 7.6.3. This message contains the new status of the xDSL NT and associated parameters since the last status report. + +An AF may routinely request for update of the status of the xDSL NT by sending a STATUS.request primitive over the $\Phi_C$ interface, as defined in clause 7.6.1. The xDSL NT shall respond with a STATUS.confirm primitive defined in clause 7.6.2, containing the required information. + +NOTE – Absence of a STATUS.confirm response is considered by the AF as "no xDSL NT compliant to this Recommendation is present". + +### 7.2.4 Discovery of AF function + +The xDSL NT and PLC network devices discover the AF by the corresponding indication in the DPM-ID TLV (DeviceInfoField) communicated in the topology query messages (see clause 7.2.5, Table 7-1). The MAC address of the AF is identified as it is carried by the SA field of the L2 protocol format of the topology query message (see Annex A). + +#### 7.2.4.1 Exchange the status information + +AF may routinely announce itself by broadcasting the STATUS.request primitive defined in clause 7.6.1 to the xDSL NT, or as defined in clause 7.6.4 to PLC-NC or to all PLC devices, or both. + +### 7.2.5 ITU-T DPM device identification + +Devices implementing this Recommendation shall send an additional vendor specific DPM device identification (DPM-ID) TLV in the topology discovery, topology query, topology response and generic PHY response messages to indicate implementation of this Recommendation and/or [IEEE 1905]. The format of DPM-ID TLV is presented in Table 7-1. + +**Table 7-1 – DPM device identification (DPM-ID) TLV** + +| Field | Length | Value range | Description | +|------------|----------|-----------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TLV-Type | 1 byte | 0B 16 | Vendor specific TLV | +| TLV-Length | 2 bytes | 0006 16 – FFFF 16 | Total number of bytes in TLV-Value field | +| TLV-Value | 3 bytes | 0019A7 16 | ITU-T OUI (the 24-bit globally unique IEEE-SA assigned value for ITU-T) | +| | 1 byte | 01 16 | ITU-T TLV subtype DPM-ID corresponding to ITU-T G.9977. It shall be fixed to the value 01 16 . | +| | 2 bytes | 0000 16 | OPCODE | +| | 1 byte | 00 16 – FF 16 | Support of IEEE 1905:
00 16 : IEEE 1905 is not supported
01 16 : IEEE 1905 is supported
02 16 – FF 16 : Reserved by ITU-T | +| | Variable | See Table 7-3 | DeviceEntry corresponding to the device sending the TLV (see Table 7-3) | + +In the case of CCM, the PLC-NC may include an additional vendor specific device status (DS) TLV in the topology response and generic PHY response messages that allows it to indicate the MAC addresses corresponding to the devices of the PLC network it is controlling. The TLV is presented in Table 7-2 and the DeviceEntry field format is presented in Table 7-3. + +**Table 7-2 – Device status (DS) TLV** + +| Field | Length | Value range | Description | +|------------|---------|-----------------------------------------|-------------------------------------------------------------------------| +| TLV-Type | 1 byte | 0B 16 | Vendor specific TLV | +| TLV-Length | 2 bytes | 0006 16 – FFFF 16 | Total number of bytes in TLV-Value field | +| TLV-Value | 3 bytes | 0019A7 16 | ITU-T OUI (the 24-bit globally unique IEEE-SA assigned value for ITU-T) | + +**Table 7-2 – Device status (DS) TLV** + +| Field | Length | Value range | Description | +|-------|---------|--------------------|-------------------------------------------------------------------------------------------------------------------------| +| | 1 byte | 01 16 | ITU-T TLV subtype DPM-ID corresponding to ITU-T G.9977. It shall be fixed to the value 01 16 . | +| | 2 bytes | 0001 16 | OPCODE | +| | 1 byte | Variable | Number (N) of devices that are in the PLC network | +| | 8 bytes | Variable | Entry corresponding to the first device of the PLC network being reported. It shall be formatted as shown in Table 7-3. | +| | ... | ... | ... | +| | 8 bytes | Variable | Entry corresponding to the N-th device of the PLC network being reported. It shall be formatted as shown in Table 7-3. | + +**Table 7-3 – DeviceEntry field format** + +| Payload field | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| MACAddress | 1-6 | 6 | MAC address of the device being reported | +| DeviceInfoField | 7-8 | 2 |

Bit map representing information related to the device being reported. Bit 0 corresponds to the LSB.

Bit 0: If set to one, it indicates that the device being reported has been incorporated into the PLC network since the last report. Zero otherwise

Bit 1: If set to one, it indicates that the device is a PLC-NC. Zero otherwise

Bit 2: If set to one, it indicates that the device is in sleep mode and is not able to transmit.

Bit 3: If set to one, it indicates that the device is an AF. Zero otherwise.

Bit 4: If set to one, it indicates that the device is an ITU-T G.993.2 NT. Zero otherwise.

Bit 5: If set to one, it indicates that the device is an ITU-T G.9701 NT. Zero otherwise.

Bit 6: If set to one, it indicates that the device supports linear interpolation of PSD. Zero otherwise.

| +| Maximum Number of PSD Bands | 9 | 1 | Maximum number of PSD bands that the device supports in the range from 8 to 32 | +| Minimum PSD Band Size | 10-13 | 4 | Minimum width for PSD band configuration the device supports in Hz, represented as an unsigned integer | +| NOTE – Other values are reserved by ITU-T. | | | | + +## 7.3 Device measurement + +### 7.3.1 Overview + +The AF coordinates the measurement of the interference between xDSL and PLC network devices. To do this, the AF may request corresponding time windows. As a result of these measurement procedures, the AF can obtain measurement data and use it to facilitate coexistence between xDSL NT and PLC network devices and optimize end-to-end throughput. The defined measurement mechanism provides the tools that: + +- allow the AF to initiate a measurement procedure that evaluates the impact of transmission of each PLC device on the xDSL access system; +- allow the AF to retrieve the measurement data (measurement results) from xDSL NT. + +A measurement procedure that evaluates the impact of xDSL transmission on the PLC devices is for further study. + +### 7.3.2 Measurement of impact from PLC devices into xDSL + +Whenever the AF identifies that a measurement of the impact of PLC network devices on xDSL NT is necessary, it shall send a MEASURE-MODE.request primitive over the $\Phi_P$ interface, as defined in clause 7.6.11, indicating to particular PLC device(s) that need to be measured during a measurement period ( $T_1$ ) specified in the MEASURE-MODE.request primitive. + +Upon reception of the MEASURE-MODE.request primitive, the PLC device in DCM or the PLC-NC in CCM shall respond with a MEASURE-MODE.confirm primitive as defined in clause 7.6.12, indicating either the availability of the device(s) to be measured to perform the measurement or its request to postpone the measurement. The device (PLC-NC in case of CCM) also indicates the delay to start the measurement period after transmission of MEASURE-MODE.confirm primitive. + +The AF may request one or more PLC devices to stop transmitting during the measurement period (i.e., the device stays silent except for the transmission of mandatory PLC signals like ACK, MAP, Beacon, etc.). Also, the AF may request one or more PLC devices to transmit continuously during the measurement period. In this case the requested PLC device shall maximize its transmission time (a best effort to increase the time of continuous transmission) and transmit a signal that is representative of the signal that would be transmitted during normal operation (e.g., the signals used for channel estimation or transmitting information). These signals shall be transmitted at the maximum transmit PSD level at which the PLC device expects to transmit when communicating with other devices in the domain, but the maximum transmit PSD level shall incorporate PSD changes applied upon request of the AF (as indicated in the latest CONFIGURE.request primitive defined in clause 7.6.7). + +In CCM, the AF shall send a MEASURE-MODE.request primitive only to the PLC-NC indicating the specific PLC devices that the AF requests to stop transmitting and the ones that the AF requests to transmit continuously during the measurement period. If the PLC-NC device responds by indicating its availability and the availability of the requested PLC devices to perform measurement, it shall make its best effort to allocate resources so that the transmission status meets the AF requirements indicated in the MEASURE-MODE.request primitive (i.e., allocate transmit opportunities, require continuous transmission from applicable devices and require applicable devices to be silent as requested by the AF). + +In DCM, the AF shall send a MEASURE-MODE.request primitive to each PLC device the AF requests to stop transmitting or to transmit continuously. If the PLC device responds indicating availability to perform measurement, it shall make best effort to meet the AF requirements indicated in the MEASURE-MODE.request primitive (i.e., either transmit continuously or stay silent as requested by the AF). + +When the AF receives a MEASURE-MODE.confirm primitive with STATUS = accepted (i.e., the requested device accepted the measurement request) it shall inform the xDSL NT that the measurement process is going to start (indicating the delay) by sending the MEASURE.request primitive via the $\Phi_C$ interface, as defined in clause 7.6.13. This primitive indicates to the xDSL NT the duration of the measurement and the delay to start. The xDSL NT shall respond to the AF with a MEASURE.confirm primitive (see clause 7.6.14). + +NOTE – A PLC device or xDSL NT may request to perform a measurement process at a particular time by sending the AF an optional STATUS.ind primitive (see clause 7.6.6) with STATUS Change type set to 0516, indicating its availability. + +The AF shall request the xDSL NT for the results of the measurement via the RESULTS.request primitive as defined in clause 7.6.17. The xDSL NT shall respond to the AF with a RESULTS.confirm primitive as defined in clause 7.16.18. The primitive includes information about the status of the measurement and the measurement data (if the measurement has been completed). + +The AF may request the xDSL NT to repeat the measurement with the aim of obtaining more comprehensive knowledge of the interference from PLC device(s) into xDSL NT. Once sufficient measurement data is obtained, the AF shall request the PLC device to complete the measurement by sending a COMPLETION.request primitive defined in clause 7.6.15 (via the $\Phi_P$ interface). Upon reception of this primitive, the PLC device(s) shall respond with COMPLETION.confirm primitive defined in clause 7.6.16 and terminate the measurement. + +If PLC network operates in CCM, the AF shall exchange the mentioned primitives over the $\Phi_P$ interface with the PLC-NC only, and the PLC-NC shall convey them to the corresponding PLC device(s) in the network. The messages communicated between the PLC-NC and the PLC device(s) for this purpose are beyond the scope of this Recommendation. + +## 7.4 Device configuration + +### 7.4.1 Overview + +The device configuration procedure allows changing transmission parameters of PLC network devices and xDSL line (xDSL NT) necessary to facilitate coexistence between the PLC network and the xDSL and optimize the overall end-to-end service delivery to the customer. The procedure is managed by the AF and performed under control of the operator. + +The configuration procedure provides the tools that: + +- allow re-configuration of selected transmission parameters of the PLC network devices; +- allow re-configuration of selected transmission parameters of the xDSL line (xDSL NT); +- facilitates a capability for both PLC devices and xDSL NT to negotiate configuration with the AF in case a compromise is necessary. + +### 7.4.2 Configuration of PLC devices + +The configuration procedure is intended to modify the transmit PSD or update a PSD limit of a particular PLC device in up to 32 frequency bands, each defined by a start frequency and a stop frequency, in a format of PSD descriptor defined in Table 7-12.1. The modification of the PSD can be used to perform a sensitivity test, while applying another PSD limit can be used to prevent excessive PSD during the entire operation of the PLC network. For devices that support linear interpolation of PSD (see Table 7-3), the relevant value of transmit PSD modification (trim) or a PSD limit on all intermediate frequencies of the band shall be computed using linear interpolation over linear frequency scale. For devices that do not support linear interpolation of PSD, it shall be modified (trimmed) using a step-shaped PSD. + +To start configuration, the AF sends across the $\Phi_P$ interface a CONFIGURE.request primitive as defined in clause 7.6.7, containing a PSD descriptor of any valid type. + +Upon reception of the CONFIGURE.request primitive, a PLC device shall reply within 2 seconds with a CONFIGURE.confirm primitive defined in clause 7.6.8, which indicates that the requested update of the transmit PSD is either confirmed or rejected. A PLC device may reject the proposed configuration if it is expected to result in disruption of transmission in the PLC network or cause some other type of critical degradation. In the case of rejection, the PLC device shall offer an alternative PSD modification (e.g., on a request to reduce PSD by a certain value, the PLC device may reply by a proposal of a smaller PSD reduction). + +Prior to replying the CONFIGURE.request primitive, the PLC device shall implement the required configuration, either the requested one, or the alternative one, if implementation of the requested one is not possible due to reasons mentioned above. The AF may require a next configuration after a time period that is not less than 2 seconds. + +If the PLC network operates in CCM, the AF is allowed to exchange the mentioned primitives over the $\Phi_P$ interface with the PLC-NC only and the PLC-NC shall convey them to the corresponding PLC device(s) in the network. The messages communicated between the PLC-NC and the PLC device(s) for this purpose are beyond the scope of this Recommendation. + +### 7.4.3 Configuration of xDSL + +The configuration procedure is capable of modifying parameters of the xDSL line with the goal of accommodating stronger crosstalk from the PLC. The configuration (or re-configuration) should be used when interference from one or more PLC devices cannot be sufficiently reduced by adjusting the transmit PSD of these devices, as described in clause 7.4.2, or for overall optimization of the end-to-end throughput. The re-configuration is achieved by modification of some xDSL parameters selected by the xDSL management entity (ME) at the network side. The modified configuration parameters shall be chosen so that they remain within the allowed range defined in the xDSL central office management information base (CO-MIB) [[ITU-T G.997.1](#)], [[ITU-T G.997.2](#)] or distribution point unit management information base (DPU-MIB) [[ITU-T G.997.2](#)]. + +To start configuration, the AF sends across the $\Phi_C$ interface a CONFIGURE.request primitive as defined in clause 7.6.9, containing the measurement data reported by the xDSL NT (SNR or QLN measurement) associated with a particular measurement scenario that AF considers as an input for xDSL re-configuration. The content and format of the reported data is defined in Table 7-14. + +Upon reception of the CONFIGURE.request primitive, the xDSL NT shall reply within 2 seconds with a CONFIGURE.confirm primitive defined in clause 7.6.10, which indicates that the request for reconfiguration of xDSL is either confirmed or rejected. The xDSL NT shall reject the configuration if it results in values of one or more of xDSL configuration parameters that violate the allowed range of configuration parameters received during initialization defined in the CO/DPU-MIB. + +NOTE – If reaching coexistence within the current range of CO/DPU-MIB parameters is impossible (i.e., the PLC network has already exhausted its means of reducing interference), the offered xDSL service may not meet the QoS requirements. In response, the operator may offer an alternative suitable range of CO/DPU-MIB parameters. The associated actions are beyond the scope of this Recommendation. + +In the case where the xDSL reconfiguration necessary to meet the required increase of the downstream SNRM violates the current CO/DPU MIB parameters, the xDSL NT may perform an alternative (partial) reconfiguration, implementing the best effort possible without violating the CO/DPU MIB. If allowed by the policy, a new MIB configuration may be requested through the $\Phi_A$ interface to achieve the downstream SNRM. + +The xDSL implements the required re-configuration by using standard procedures defined for the particular xDSL, such as on-line reconfiguration (OLR), SAVN update, etc. See [[ITU-T G.993.2](#)], [[ITU-T G.9701](#)] and [[ITU-T G.998.4](#)]. More specifically, the xDSL shall take into account the measured SNR and/or the measured QLN data provided by the AF into its bit-loading calculation by treating the interference as additional noise generated by the PLC device. This may help in stabilizing the xDSL link in the presence of the time-varying interference from the PLC device. After completion + +of the reconfiguration, the xDSL NT shall indicate to the AF the completion of the re-configuration by sending a STATUS.ind primitive via the $\Phi_C$ interface. The AF shall not request next xDSL reconfiguration within 15 seconds of the current re-configuration. + +## 7.5 Primitives supporting coexistence protocol + +The list of primitives that facilitate coordination between xDSL NT and PLC network for the logical interfaces $\Phi_P$ , $\Phi_C$ , and $\Phi_A$ is presented in Table 7-4. + +**Table 7-4 – Primitives at interfaces $\Phi_C$ , $\Phi_P$ and $\Phi_A$** + +| Primitive | Direction | Description | +|----------------------|----------------------|----------------------------------------------------------------------------------------------------------------------------| +| $\Phi_C$ | | | +| STATUS.request | AF $\rightarrow$ NT | Requests an update of the status of the xDSL link and the xDSL NT | +| STATUS.confirm | NT $\rightarrow$ AF | Delivers an update on the xDSL link and xDSL NT status | +| STATUS.ind | NT $\rightarrow$ AF | Informs on changes to the xDSL NT status (ON, OFF, etc.) and the status of the xDSL link | +| MEASURE.request | AF $\rightarrow$ NT | Requests to start measurements to facilitate the interference measurement from PLC to xDSL | +| MEASURE.confirm | NT $\rightarrow$ AF | Informs that SNR measurement request was received | +| RESULTS.request | AF $\rightarrow$ NT | Request an update of measurements results including:
SNR
QLN (if applicable) | +| RESULTS.confirm | NT $\rightarrow$ AF | Reports SNR/QLN measurement results to the AF | +| CONFIGURE.request | AF $\rightarrow$ NT | Request to re-configure the xDSL line | +| CONFIGURE.confirm | NT $\rightarrow$ AF | Confirms the re-configuration of the xDSL line | +| $\Phi_P$ | | | +| STATUS.request | AF $\rightarrow$ PLC | Requests an update of the status of the PLC network relevant information:
Number of PLC devices
PLC network topology | +| STATUS.confirm | PLC $\rightarrow$ AF | Delivers an update of the PLC network status | +| STATUS.ind | PLC $\rightarrow$ AF | Informs on a change of the PLC network status (new device joining, device turns to a sleep mode, etc.) | +| MEASURE-MODE.request | AF $\rightarrow$ PLC | Requests to launch a procedure to measure the interference from PLC to xDSL | +| MEASURE-MODE.confirm | PLC $\rightarrow$ AF | Informs the AF whether the request is granted or not; if granted, the PLC shall start the measurement procedure | +| COMPLETION.request | AF $\rightarrow$ PLC | Requests information about completion of the previous Measurement procedure | +| COMPLETION.confirm | PLC $\rightarrow$ AF | Informs the status of the measurement period and the transmission duty cycle | + +**Table 7-4 – Primitives at interfaces $\Phi_C$ , $\Phi_P$ and $\Phi_A$** + +| Primitive | Direction | Description | +|----------------------------------------------------------------------------------------------|----------------------|--------------------------------------------------------------------------------------------------------------------| +| $\Phi_C$ | | | +| CONFIGURE.request | AF $\rightarrow$ PLC | Requests a re-configuration of a PLC network device (e.g., modify its transmit PSD) | +| CONFIGURE.confirm | PLC $\rightarrow$ AF | Confirms the re-configuration of the PLC network device | +| $\Phi_A$ (Note) | | | +| STATUS.request | NMS $\rightarrow$ AF | Requests an update of the status of the AF at the RGW:
PLC status
xDSL NT status
RGW topology
Policies | +| STATUS.confirm | AF $\rightarrow$ NMS | Update on the AF status | +| STATUS.ind | AF $\rightarrow$ NMS | Informs of an update in the AF status | +| CONFIGURE.request | NMS $\rightarrow$ AF | Requests to configure or re-configure the AF, including
Active/Inactive
Policies | +| CONFIGURE.confirm | AF $\rightarrow$ NMS | Confirms the re-configuration of the AF | +| NOTE – The primitives at the $\Phi_A$ interface defined in this table are for further study. | | | + +## 7.6 Description of primitives + +The primitive exchange across the $\Phi_P$ , $\Phi_C$ and $\Phi_A$ interfaces shall have the following properties: + +- the exchange contains a set of request – response pairs of primitives (except for indication primitives); +- each primitive may carry more than one parameter; +- the type of the primitive is determined by the OPCODE that indicates the interface across which this primitive is exchanged, whether the primitive is a request, or a response, or an indication and specific parameter(s) carried by this primitive. + +The entity initiating the primitive transaction (e.g., AF or PLC device or xDSL NT) shall send a request (a .request primitive) and wait for a response (a .confirm primitive). If no response is received during the defined timeout, depending on the type of the request, the request primitive may be either retransmitted or abandoned. A timeout of two seconds should be used if no specific timeout is defined for a particular primitive exchange. A mandatory requirement is for further study. + +The list of request primitives and corresponding response primitives and indication primitives is shown in Table 7-5. An indication (an .ind primitive) is considered as a request with no response required. If after an indication is sent, no expected activity is detected within 10 seconds, it may imply that the indication is lost. In this case, the indication shall be sent again with any updates. A response (a .confirm primitive) may include no parameters associated (simple acknowledgement). + +Whenever the entities exchange primitives across the $\Phi_P$ , $\Phi_C$ or $\Phi_A$ interfaces over Layer 2, the primitives shall be mapped into messages using protocol formats defined in clause A.1.1. Each message communicates primitives which are mapped to a TLV along with its 2-byte OPCODE. + +**Table 7-5 – Request and response primitives** + +| Primitive type
(OPCODE bits
[15:8]; for
OPCODE bits
[7:0] see (Note 1)) | Primitive
type
name | Primitives | Application | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------|------------------------------------------------|------------------------------------------------------------------------------------------------------| +| ΦC interface | | | | +| 00001000 | Status | STATUS.request
STATUS.confirm
STATUS.ind | Update of the status of the xDSL NT | +| 00001001 | Configure | CONFIGURE.request
CONFIGURE.confirm | Reconfiguration of the xDSL NT | +| 00001100 | Measure | MEASURE.request
MEASURE.confirm | Facilitate a measurement of the interference from PLC device(s) into xDSL | +| 00001010 | Results | RESULTS.request
RESULTS.confirm | Update of measurement results (SNR) performed by the xDSL NT | +| ΦP interface | | | | +| 00001000 | Status | STATUS.request
STATUS.confirm
STATUS.ind | Update of the status of the PLC network | +| 00001001 | Configure | CONFIGURE.request
CONFIGURE.confirm | Reconfiguration of the PLC device(s) (modify transmit PSD) | +| 00001011 | Measure | MEASURE-MODE.request
MEASURE-MODE.confirm | Facilitate a measurement of the interference from PLC device(s) into xDSL | +| 00001100 | Completion | COMPLETION.request
COMPLETION.confirm | Provide feedback about the completion of the measurement and the duty cycle from PLC device(s) to AF | +| ΦA interface (Note 2) | | | | +| 00001000 | Status | STATUS.request
STATUS.confirm
STATUS.ind | Update of the status of the AF, xDSL NT, and PLC network | +| 00001001 | Configure | CONFIGURE.request
CONFIGURE.confirm | Reconfiguration of the AF (new arbitration policies) | +|

NOTE 1 – The bits [7:0] of the 2-byte OPCODE field of the primitive shall use the following format:

  • – bits [0:1] – identify the AF interface: 00 for ΦP, 11 for ΦC, 01 for ΦA, and 10 – reserved by ITU-T;
  • – bits [2:3] – identify whether the primitive is a command or a response with the following coding: 11 = request, 10 = indication, 01 = confirmation, 00 = reserved by ITU-T;
  • – bits [4:6] – indicate the type of the primitive communicated: 000 = STATUS, 001 = CONFIGURE, 010 = MEASURE, 011 = RESULTS, 100 = MEASURE-MODE, 101 = COMPLETION, 110 and 111 = reserved by ITU-T;
  • – bit [7] – reserved by ITU-T and shall be set to 0.

NOTE 2 – The primitives at the ΦA interface defined in this table are for further study.

| | | | + +### 7.6.1 STATUS.request primitive ( $\Phi_c$ interface) + +The STATUS.request primitive is used by the AF to request the current status of the xDSL NT. The xDSL NT shall reply to it by sending STATUS.confirm primitive (see clause 7.6.2). The first 2 bytes of the STATUS.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-6. + +**Table 7-6 – Parameters of the STATUS.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|----------------|--------------|-----------------------|----------------------------------------------------| +| STATUS REQ | N/A | 0 | The TLV-Value Parameter of this primitive is empty | + +### 7.6.2 STATUS.confirm primitive ( $\Phi_c$ interface) + +The STATUS.confirm primitive is used by the xDSL NT to report the current status of the xDSL access network on request from the AF (STATUS.request). The first 2 bytes of the STATUS.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-7. + +**Table 7-7 – Parameters of the STATUS.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| xDSL access network STATUS | 3 | 1 | 00 16 – Inactive
01 16 – Initialization
02 16 – Re-initialization
10 16 – Showtime, QoS met
11 16 – Showtime, QoS violation
03 16 – Deactivation
(Note) | +| NOTE – Other values are reserved by ITU-T. | | | | + +### 7.6.3 STATUS.ind primitive ( $\Phi_c$ interface) + +The STATUS.ind primitive is used by the xDSL NT to indicate a change in the status of the xDSL access network to the AF (idle, initialization, showtime, disconnect, etc.). The first 2 bytes of the STATUS.ind primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-8. + +**Table 7-8 – Parameters of the STATUS.ind primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Previous xDSL access network STATUS | 3 | 1 | 00 16 – Inactive
01 16 – Initialization
02 16 – Re-initialization
10 16 – Showtime, QoS met
11 16 – Showtime, QoS violation
03 16 – Deactivation
(Note) | +| Current xDSL access network STATUS | 4 | 1 | 00 16 – Inactive
01 16 – Initialization
02 16 – Re-initialization
10 16 – Showtime, QoS met
11 16 – Showtime, QoS violation
03 16 – Deactivation
(Note) | +| NOTE – Other values are reserved by ITU-T. | | | | + +### 7.6.4 STATUS.request primitive (ΦP interface) + +The STATUS.request primitive is used by the AF to request the current status of the PLC network. The requested PLC device in case of DCM or the PLC-NC in case of CCM shall reply to it by sending STATUS.confirm primitive (see clause 7.6.5). The first 2 bytes of the STATUS.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-9. + +For PLC network operating in CCM, the destination address value in the header of L2 message carrying this primitive (see Table A.1) shall be the MAC address associated with the domain master, which is the PLC-NC of the network and keeps an updated status of the PLC network. + +**Table 7-9 – Parameters of the STATUS.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|---------------------|--------------|-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| STATUS Request Type | 3 | 1 | Type of the status request.
00 16 : Full report. In CCM, the PLC-NC reports the status of all the devices in the PLC network. In DCM, the receiver of this primitive reports the status related to the device.
01 16 : Partial report. In CCM, the PLC-NC reports the status of all the devices included in this request. This value is not applicable in DCM.
(Note) | +| Number of devices | 4 | 1 | Unsigned integer representing the number of PLC devices (j) for which a status is requested.
This field only exists if STATUS Request Type is set to 01 16 . | + +**Table 7-9 – Parameters of the STATUS.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|-----------------|------------------------|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------| +| MACAddress[0] | 5-10 | 6 | MAC address of the first PLC device for which a status is requested. This field only exists if STATUS Request Type is set to 01 16 . | +| ... | ... | ... | ... | +| MACAddress[j-1] | 5+(j-1)*6 – 10+(j-1)*6 | 6 | MAC address of the last PLC device for which a status is requested. This field only exists if STATUS Request Type is set to 01 16 . | + +NOTE – Other values are reserved by ITU-T. + +### 7.6.5 STATUS.confirm primitive (ΦP interface) + +The STATUS.confirm primitive is used by the PLC network to reply with the current status of the PLC network on request of the AF (STATUS.request). The first 2 bytes of the STATUS.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-10 and the format of the Device status sub-field is shown in Table 7-10.1. + +**Table 7-10 – Parameters of the STATUS.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------|--------------|-----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Number of devices | 3 | 1 | The number of devices for which the information is reported represented as an unsigned integer in the range from 1 to 255.
The first entry in the list of status of the PLC devices corresponds to the device that sends the report. | +| Status of Device 1 | variable | variable | A sub-field that defines the status of Device #1 of the PLC network. This sub-field shall follow the format described by Table 7-10.1. | +| ..... | ..... | ..... | | +| Status of Device M | variable | variable | A sub-field that defines the status of Device #M of the PLC network, where M is the total number of devices. The format of this sub-field is defined in Table 7-10.1. | + +**Table 7-10.1 – Parameters of the Device status sub-field** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Length | 1 | 2 | Length in bytes of the PLC device status sub-field represented as an unsigned integer | +| MACAddress | 3 | 6 | MAC address of the reported device | +| PowerState | 9 | 1 | 00 16 : Reported device is in a normal power state
01 16 : Reported device is in a low power state
02 16 : Reported device is OFF
(Note) | +| DeviceType | 10 | 1 | 00 16 : Reported device is a PLC-NC
01 16 : Reported device is not a PLC-NC
(Note) | +| LowFrequency | 11 | 1 | Unsigned integer representing the lowest frequency (in units of 1 MHz) the reported device is using for transmissions | +| HighFrequency | 12 | 1 | Unsigned integer representing the highest frequency (in units of 1 MHz) the reported device is using for transmissions | +| PSDType | 13 | 1 | 00 16 – Standard PSD (no PSD cutback associated with xDSL coexistence)
01 16 – Modified PSD defined in the "PSD descriptor" field (to facilitate xDSL coexistence)
(Note) | +| PSDType Configuration ID | 14 | 2 | A 2-byte integer associated with the latest configuration applied, assigned by the AF (see Table 7-12, Configuration ID). This field shall be set to zero and ignored by the receiver if PSDType field is 00 16 . | +| Last measurement ID | 16 | 2 | Measurement ID of the last MEASURE-MODE.request received and responded with MEASURE-MODE.confirm.
The initial value for this field is zero (when no previous MEASURE-MODE request has been processed). | +| Number of bands | 18 | 1 | The number of bands used in the PSD descriptor in the range between 0 and 32, represented as an unsigned integer. The value of zero indicates no PSD change and the PSD descriptor shall not be included. | +| PSD descriptor | 19 – t+18 | t | A t-byte sub-field describing the PSD of the PLC device (see Table 7-12.1) | +| NOTE – Other values are reserved by ITU-T. | | | | + +### 7.6.6 STATUS.ind primitive (ΦP interface) + +The STATUS.ind primitive is used by the PLC network to indicate a change in its current status (that may require action from the AF). The first 2 bytes of the STATUS.ind primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-11. + +**Table 7-11 – Parameters of the STATUS.ind primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| STATUS change type | 3 | 1 | 01 16 – One or more devices added to the PLC network
02 16 – One or more devices left the PLC network
03 16 – One or more PLC devices turned to low power state
04 16 – One or more PLC devices came back from low power state
05 16 – PLC network/device is ready for a measurement procedure
(Note) | +| Number of devices | 4 | 1 | Number of PLC devices (N) for which the status changed | +| MAC device 1 | 5 | 6 | MAC address of the first PLC device for which the status changed | +| ..... | ..... | ..... | ..... | +| MAC device N | 5+6*(N-1) | 6 | MAC address of the last PLC device for which the status changed | +| NOTE – Other values are reserved by ITU-T. | | | | + +### 7.6.7 CONFIGURE.request primitive (ΦP interface) + +The CONFIGURE.request primitive is used by the AF to request modification of the parameters of PLC devices. The PLC shall reply to it by sending CONFIGURE.confirm primitive (see clause 7.6.8). The first 2 bytes of the CONFIGURE.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-12. + +**Table 7-12 – Parameters of the CONFIGURE.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------|--------------|-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Configuration ID | 3-4 | 2 | A 2-byte unsigned integer associated with the requested configuration, assigned by the AF (Note 1) | +| PSDType | 5 | 1 | 00 16 – Standard PSD (no PSD cutback associated with xDSL coexistence)
01 16 – Modified PSD defined in the "PSD descriptor" field (to facilitate xDSL coexistence)
(Note 2) | +| Configuration type | 6 | 1 | 00 16 – PSD modification request is to change the transmit PSD at which the device operates
01 16 – PSD modification request is only for measurement purpose (Note 3)
(Note 2) | +| Number of bands | 7 | 1 | The number of bands ( N ) used in the PSD descriptor in the range between 0 and 32, represented as an unsigned integer. The value of | + +**Table 7-12 – Parameters of the CONFIGURE.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|-------------------|--------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | | zero indicates no PSD change and the PSD descriptor shall not be included. | +| PSD update type | 8 | 1 | Indicates the type of PSD update:
00 16 – update of the PSD limit mask
01 16 – update of the TX PSD (step up or down comparing to the currently used PSD)
(Note 2) | +| PSD descriptor | 8 – (t+7) | t | A t -byte sub-field describing the PSD of the PLC device (see Table 7-12.1) | +| Number of devices | Variable | 1 | Number of PLC devices (V) for which the PSD descriptor in this primitive is applicable | +| MAC device 1 | Variable | 6 | MAC address of the first PLC device for which the PSD descriptor is applicable | +| ..... | ..... | ..... | ..... | +| MAC device V | Variable | 6 | MAC address of the last PLC device for which the PSD descriptor is applicable | + +NOTE 1 – The value of Configuration ID shall be incremented for every subsequent configuration request. When it reaches 216, it wraps around to zero. +NOTE 2 – Other values are reserved by ITU-T. +NOTE 3 – The AF can change the transmit PSD using the CONFIGURE.request primitive regardless of the Configuration type set in the previous instance of the CONFIGURE.request primitive. + +The format of the sub-field describing the PSD is defined in Table 7-12.1 and the format of the band PSD descriptor is shown in Table 7-12.2. + +**Table 7-12.1 – Format of *t*-byte PSD descriptor** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|----------------|-----------------------------|-----------------------|------------------------------------------------------| +| Band 1 | 1-10 | 10 | Band 1 PSD descriptor (see Table 7-12.2) | +| Band 2 | 11-20 | 10 | Band 2 PSD descriptor (see Table 7-12.2) | +| ..... | ..... | ..... | ..... | +| Band #N | [10*(N-1)+1]
-
[10*N] | 10 | Band N PSD descriptor (N ≤ 32)
(see Table 7-12.2) | + +**Table 7-12.2 – Format of band PSD descriptor** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|-----------------------|-----------------------------------------------------------------------------------------------------------------| +| START_FREQ | 1-4 | 4 | Start frequency in Hz, represented as an unsigned integer | +| START_PSD | 5 | 1 | The value of PSD or PSD step:
in units of 1 dB, represented as twos-complimentary integer (Note 1), (Note 2) | +| END_FREQ | 6-9 | 4 | End frequency in Hz, represented as an unsigned integer | +| END_PSD | 10 | 1 | The value of PSD or PSD step:
in units of 1 dB, represented as twos-complimentary integer (Note 1), (Note 2) | +| NOTE 1 – Depending on the PSD update type, the following representation shall be used:
– update of PSD limit, in the range between –85 dBm/Hz to –50 dBm/Hz;
– update of the TX PSD (PSD step), in the range between –35 dB to 35 dB.
NOTE 2 – For devices that support linear interpolation of PSD (see Table 7-3), PSD values are linearly interpolated over frequency between START_FREQ and END_FREQ (in dB scale). For devices that do not support linear interpolation of PSD, PSD values shall be constant over frequency between START_FREQ and END_FREQ (in dB scale). | | | | + +### 7.6.8 CONFIGURE.confirm primitive ( $\Phi_P$ interface) + +The CONFIGURE.confirm primitive is used by the PLC to reply on CONFIGURE.request primitive. The first 2 bytes of the CONFIGURE.confirm primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-13. + +**Table 7-13 – Parameters of the CONFIGURE.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Configuration ID | 3-4 | 2 | A 2-byte integer associated with the confirmed configuration (indicated in the CONFIGURE.request) | +| STATUS | 5 | 1 | 00 16 – Request completed
01 16 – Request rejected and alternative change proposed in the "PSD descriptor" field
02 16 – Request rejected due to invalid parameters (Note) | +| Number of bands | 6 | 1 | The number of bands ( N ) used in the PSD descriptor in the range between 1 and 16, represented as an unsigned integer.
This field shall be set to 00 16 if STATUS = 00 16 or 02 16 and shall be different from 00 16 if STATUS = 01 16 .
The value of zero indicates no PSD change and the PSD descriptor shall not be included. | +| PSD descriptor | 7 – (t+6) | t | A t -byte sub-field describing the PSD of the PLC device (see Table 7-12.1) | +| NOTE – Other values are reserved by ITU-T. | | | | + +### 7.6.9 CONFIGURE.request primitive ( $\Phi_C$ interface) + +The CONFIGURE.request primitive is used by the AF to request modification of the xDSL line parameters based on the reported measurement data. The xDSL NT shall reply to it by sending CONFIGURE.confirm primitive (see clause 7.6.10). The first 2 bytes of the CONFIGURE.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-14. + +**Table 7-14 – Parameters of the CONFIGURE.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|-----------------------|--------------|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Configuration ID | 3-4 | 2 | A 2-byte integer associated with the requested configuration, assigned by the AF (Note 1) | +| Measurement data type | 5 | 1 | 00 16 – SNR measurement
01 16 – QLN measurement
02 16 – the xDSL may initialize, no measurement data provided
(Note 2) | +| Measurement data | 6 – (5+s) | s | This field contains the reported measurement data (upon the latest measurement request) in the format defined in the field SNR/QLN descriptor of the RESULTS.confirm primitive (see clause 7.6.18, Table 7-23.1). This field is not present when measurement data type equals 02 16 . | + +NOTE 1 – The value of Configuration ID shall be incremented for every subsequent configuration request. When it reaches $2^{16}$ , it wraps around to zero. +NOTE 2 – Other values are reserved by ITU-T. + +### 7.6.10 CONFIGURE.confirm primitive ( $\Phi_C$ interface) + +The CONFIGURE.confirm primitive is used by the xDSL NT to reply to a CONFIGURE.request primitive. It either confirms or rejects making modifications of the xDSL link parameters based on the measurement data provided by the AF. The first 2 bytes of the CONFIGURE.confirm primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-15. + +**Table 7-15 – Parameters of the CONFIGURE.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|------------------|--------------|-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Configuration ID | 3-4 | 2 | A 2-byte integer associated with the confirmed configuration
(indicated in the CONFIGURE.request) | +| STATUS | 5 | 1 | 00 16 – The requested reconfiguration based on the measurement data provided by the AF is accepted
01 16 – The requested reconfiguration based on the measurement data provided by the AF is rejected
(Note) | + +NOTE – Other values are reserved by ITU-T. + +### 7.6.11 MEASURE-MODE.request primitive ( $\Phi_P$ interface) + +The MEASURE-MODE.request primitive is used by the AF to request a PLC device to start the measurement procedure. The PLC device shall reply to it by sending MEASURE-MODE.confirm primitive (see clause 7.6.12). The first 2 bytes of the MEASURE-MODE.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-16. + +**Table 7-16 – Parameters of the MEASURE-MODE.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|------------------|------------------|-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the requested measurement, assigned by the AF (Note) | +| Measurement time | 5-8 | 4 | The measurement time ( $T_1$ ) expressed in ms and represented as an unsigned integer. During this time period the PLC device shall transmit or remain silent as requested (see clause 7.3.2). | +| N transmit | 9 | 1 | Number of PLC devices that make best effort to transmit all the time during the measurement time | +| MAC device 1 | 10 | 6 | MAC address of the first PLC device in the transmission list | +| ..... | ..... | ..... | ..... | +| MAC device N | $10+6*(N-1)$ | 6 | MAC address of the last PLC device in the transmission list | +| M silence | $10+6*N$ | 1 | Number of PLC devices that stop transmitting during the measurement time (see clause 7.3.2) | +| MAC device 1 | $11+6*N$ | 6 | MAC address of the first PLC device in the silence list | +| ..... | ..... | ..... | ..... | +| MAC device M | $11+6*N+6*(M-1)$ | 6 | MAC address of the last PLC device in the silence list | + +NOTE – The value of Measurement ID shall be incremented for every subsequent measurement request. When it reaches $2^{16}$ , it wraps around to zero. + +### 7.6.12 MEASURE-MODE.confirm primitive ( $\Phi_P$ interface) + +The MEASURE-MODE.confirm primitive is used by the PLC to reply on the MEASURE-MODE.request primitive and thus confirm that the addressed PLC device starts the measurement procedure. The PLC device may defer the request with a reason code. The first 2 bytes of the MEASURE-MODE.confirm primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-17. + +**Table 7-17 – Parameters of the MEASURE-MODE.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|------------------------------|--------------|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the requested measurement (indicated in the MEASURE-MODE.request) | +| STATUS | 5 | 1 | 00 16 – Accepted, and all PLC devices requested by the AF to transmit will start to make best effort to transmit all the time and all PLC devices requested by the AF to stay silent will be silent in DELAY milliseconds (see clause 7.3.2)
01 16 – Rejected (Note 1) | +| DELAY | 6-7 | 2 | This field is the delay in milliseconds (represented as an unsigned integer) after sending this primitive. The measurement procedure actually starts after this time has elapsed. In case of CCM, the value of this field is generated by the PLC-NC. | +| Number of devices | 8 | 1 | Number of PLC devices (R) for which the request was rejected | +| MAC device 1 | 9 | 6 | MAC address of the first PLC device for which the request is rejected | +| Rejection reason | 15 | 1 | 01 16 – Busy
02 16 – Rejected: measurement time too short
03 16 – Rejected: measurement time too long (Note 1) | +| Recommended measurement time | 16-19 | 4 | Recommended measurement time (Note 2):
Maximum valid time in case rejection is for too short (Rejection reason = 02 16 )
Minimum valid time in case rejection is for too long (Rejection reason = 03 16 ) | +| ..... | ..... | ..... | ..... | +| MAC device R | variable | 6 | MAC address of the last PLC device for which the request was rejected | +| Rejection reason | variable | 1 | 01 16 – Busy
02 16 – Rejected: measurement time too short
03 16 – Rejected: measurement time too long (Note 1) | +| Recommended measurement time | variable | 4 | Recommended measurement time (Note 2):
Maximum valid time in case rejection is for too short (Rejection reason = 02 16 )
Minimum valid time in case rejection is for too long (Rejection reason = 03 16 ) | + +NOTE 1 – Other values are reserved by ITU-T. +NOTE 2 – In case Rejection reason is "Busy", this field shall indicate the recommended measurement time. + +### 7.6.13 MEASURE.request primitive ( $\Phi_C$ interface) + +The MEASURE.request primitive is used by the AF to request the xDSL NT to start the measurement procedure. The xDSL NT shall reply to it by sending MEASURE.confirm primitive (see clause 7.6.14). The first 2 bytes of the MEASURE.request primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-18. + +**Table 7-18 – Parameters of the MEASURE.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|-------------------|--------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the requested measurement, assigned by the AF (Note) | +| Measurement delay | 5-6 | 2 | The measurement start time relative to the instant the MEASURE.request primitive is sent, expressed in ms units and represented as an unsigned integer | +| Measurement time | 7-8 | 2 | The measurement time expressed in ms and represented as an unsigned integer ( $T_1$ ). During this time period the xDSL NT shall measure and store the SNR or QLN that includes the impact of the PLC device. | + +NOTE – The value of Measurement ID shall be incremented for every subsequent measurement request. When it reaches $2^{16}$ , it wraps around to zero. + +### 7.6.14 MEASURE.confirm primitive ( $\Phi_C$ interface) + +The MEASURE.confirm primitive is used by the xDSL NT to reply on MEASURE.request primitive and thus confirm the start of the measurement procedure. The xDSL NT cannot reject the MEASURE.request if in showtime. The first 2 bytes of the MEASURE.confirm primitive (OPCODE) shall be as defined in Table 7-5. The payload of the TLV-Value field (m-bytes) is presented in Table 7-19. + +**Table 7-19 – Parameters of the MEASURE.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|----------------|--------------|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the requested measurement (indicated in the MEASURE.request) | +| STATUS | 5 | 1 | $00_{16}$ – $02_{16}$ – Accepted; the measurement procedure will start at the requested time and for requested duration
– $00_{16}$ – xDSL NT is in L0 state (showtime)
– $01_{16}$ – xDSL NT is in L2.1 state (showtime)
– $02_{16}$ – xDSL NT is in L2.2 state (showtime)
$03_{16}$ – $04_{16}$ – Rejected: SNR measurement is not available
– $03_{16}$ – xDSL NT is in initialization
– $04_{16}$ – xDSL NT is idle (L3 state)
(Note) | + +NOTE – Other values are reserved by ITU-T. + +### 7.6.15 COMPLETION.request primitive ( $\Phi_P$ interface) + +The COMPLETION.request primitive is used by the AF to request to a PLC device to confirm completion of the measurement previously requested. The PLC device shall reply to it by sending COMPLETION.confirm primitive (see clause 7.6.16). The first 2 bytes of the COMPLETION.request primitive (OPCODE) shall be as defined in Table 7-5. The rest of the TLV-Value field (m-bytes) is presented in Table 7-20. + +**Table 7-20 – Parameters of the COMPLETION.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|-------------------|--------------|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the requested measurement shall be identical to the one used for the corresponding MEASURE-MODE.request (see clause 7.6.11) | +| Number of devices | 5 | 1 | Number of PLC devices (N) for which MEASURE-MODE.request was sent | +| MAC device 1 | 6 | 6 | MAC address of the first PLC device in the list | +| ..... | ..... | ..... | ..... | +| MAC device N | 6*N | 6 | MAC address of the last PLC device in the list | + +### 7.6.16 COMPLETION.confirm primitive ( $\Phi_P$ interface) + +The COMPLETION.confirm primitive is used by the PLC device to provide feedback and confirm the completion of a previously requested measurement. The first 2 bytes of the COMPLETION.confirm primitive (OPCODE) shall be as defined in Table 7-5. The rest of the TLV-Value field (m-bytes) is presented in Table 7-21. + +**Table 7-21 – Parameters of the COMPLETION.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|--------------|-----------------------|-------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the confirmed measurement (indicated in COMPLETION.request) | +| STATUS | 5 | 1 | 00 16 : measurement completed
01 16 : measurement not completed yet
(Note) | +| Number of devices | 6 | 1 | Number of PLC devices for which COMPLETION.request was sent | +| MAC device 1 | 7 | 6 | MAC address of the first PLC device in the list | +| DUTY_CYCLE of device 1 | 13 | 1 | Percentage of time that the PLC device corresponding to MAC device 1 has been transmitting during the measurement | +| ..... | ..... | ..... | ..... | +| MAC device N | variable | 6 | MAC address of PLC device N in the list | +| DUTY_CYCLE of device N | variable | 1 | Percentage of time that the PLC device corresponding to MAC device N has been transmitting during the measurement | +| NOTE – Other values are reserved by ITU-T. | | | | + +### 7.6.17 RESULTS.request primitive ( $\Phi_c$ interface) + +The RESULTS.request primitive is used by the AF to request the xDSL NT to send the measurement results. The xDSL NT shall reply to it by sending RESULTS.confirm primitive (see clause 7.6.18). The first 2 bytes of the RESULTS.request primitive (OPCODE) shall be as defined in Table 7-5. The rest of the TLV-Value field (m-bytes) is presented in Table 7-22. + +In case the xDSL system uses frequency division duplexing, such as VDSL2 [ITU-T G.993.2], the AF should use a separate RESULTS.request primitive for every relevant downstream band. + +**Table 7-22 – Parameters of the RESULTS.request primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|----------------|--------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the requested measurement shall be identical to the one used for the corresponding MEASURE.request (see clause 7.6.13) | +| Group size | 5 | 1 | The tone group size ( $G$ ) used for SNR/QLN report with valid values consistent with relevant xDSL Recommendation | +| START_Index | 6-7 | 2 | The group index associated with the lowest frequency of the requested SNR/QLN report represented as unsigned integer | +| END_Index | 8-9 | 2 | The group index associated with the highest frequency of the requested SNR/QLN report represented as unsigned integer | + +### 7.6.18 RESULTS.confirm primitive ( $\Phi_c$ interface) + +The RESULTS.confirm primitive is used by the xDSL NT to provide the measurement results. The first 2 bytes of the RESULTS.confirm primitive (OPCODE) shall be as defined in Table 7-5. The rest of the TLV-Value field (m-bytes) is presented in Table 7-23. + +**Table 7-23 – Parameters of the RESULTS.confirm primitive** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|--------------------------------------------|-----------------|-----------------------|--------------------------------------------------------------------------------------------------------------| +| Measurement ID | 3-4 | 2 | A 2-byte integer associated with the confirmed measurement (indicated by MEASURE.request) | +| STATUS | 5 | 1 | 00 16 – measurement completed
01 16 – measurement failed
(Note) | +| MODE | 6 | 1 | 00 16 – reported data represents SNR
01 16 – reported data represents QLN
(Note) | +| DURATION | 7-10 | 4 | Total measurement duration in milliseconds units (represented as an unsigned integer) | +| SNR/QLN descriptor | 11 – ( $d+10$ ) | $d$ | A sub-field representing the SNR/QLN descriptor (see Table 7-23.1) | +| NOTE – Other values are reserved by ITU-T. | | | | + +**Table 7-23.1 – Format of SNR/QLN descriptor** + +| Parameter name | Octet number | Field size (in bytes) | Description | +|-----------------------|---------------------|------------------------------|---------------------------------------| +| Group #1 | 1 | 1 | The SNR/QLN value for Group #1 (Note) | +| Group #2 | 2 | 1 | The SNR/QLN value for Group #2 (Note) | +| ..... | ..... | ..... | ..... | +| Group #N | N | 1 | The SNR/QLN value for Group #N (Note) | + +NOTE – The format of the SNR/QLN values, including use of special values, shall be as defined in the associated xDSL Recommendations [[ITU-T G.993.2](#)], [[ITU-T G.9701](#)], etc. One of the special values indicates the groups for which SNR/QLN values are unavailable. + +# Annex A + +## Transmission formats for message exchange + +(This annex forms an integral part of this Recommendation.) + +## A.1 Transmission formats + +Layer 2 transmission format is defined (see clause A.1.1). Other transmission formats are for further study. + +### A.1.1 Layer 2 transmission format + +The L2 protocol format at both $\Phi_C$ and $\Phi_P$ interfaces shall use the IEEE 1905 compatible format which makes use of IEEE Std 802.3-2008 MAC frame format at layer 2 (L2) of the protocol stack, as presented in Figure 3-1 of [IEEE 802.3]. + +Table A.1 – L2 protocol format + +| Field | Length | Value range | Description | +|---------------------|---------------|------------------|-------------------------------------------------------------------------------------------------| +| Destination address | 6 bytes | Any EUI-48 value | MAC address of the receiving device (xDSL NT, or a PLC device, or the AF) | +| Source address | 6 bytes | Any EUI-48 value | MAC address of the source device (xDSL NT, or a PLC device, or the AF) | +| EtherType | 2 bytes | 0x893A | EtherType field defines the type of MAC protocol (IEEE 1905 in this case) | +| CMDU payload | 46-1500 bytes | See Table A.2 | CMDU payload, including one or more messages. The format of the payload is defined in Table A.2 | +| FCS | 4 bytes | Any 4-byte value | Frame check sequence field computed as defined in clause 3.2.9 of [IEEE 802.3] | + +The control message data unit (CMDU) is intended to carry primitives associated with the coexistence mechanism defined in this specification (over the $\Phi_C$ , $\Phi_P$ and $\Phi_A$ interfaces). The format of the CMDU is presented in Table A.2 and consists of the header and the payload. + +The primitives carried by the CMDU are formatted as TLV; the CMDU payload contains: + +- the TLV-field that carries a single TLV or a number of concatenated TLVs; +- the End TLV field that indicates the end of the CMDU payload (see Table A.2). + +The rest of the CMDU fields defined in Table A.2 represent the CMDU header (8 bytes in total). + +If a primitive to be transmitted in the CMDU contains more than 1500 bytes, it shall be communicated using multiple CMDUs, while every CMDU carries a fragment of the primitive. The fragmentation rule is defined in [IEEE 1905.1]; the header of the CMDU indicates the fragment number and total number of fragments. + +The CMDU format is defined in Table A.2 and is consistent with the IEEE 1905 CMDU format as defined in Table 6-3 of [IEEE 1905.1]. + +**Table A.2 – CMDU format** + +| Field | Length | Value range | Description | +|-------------------------|---------------|-----------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message version | 2 bytes | N/A | Set to zero on transmission | +| Message type | 2 bytes | 0004 16 | All messages related to this Recommendation shall be of the same Type = 0004 16 ([IEEE 1905.1], vendor specific) | +| Message ID | 2 bytes | 0000 16 – FFFF 16 | An ID assigned for each message; the receiver uses the ID to process messages in the order they were sent. If it is a response message, the value MUST be set to the same value as that of the received request message; otherwise, set to a new value. | +| Fragment ID | 1 byte | 00 16 – 40 16 | Identifies the fragment of a message with the given message ID. Message can be divided by up to 64 fragments.
The value starts from 0 for the first fragment and monotonically increases by 1 for the successive fragments.
If the message is not fragmented, the value MUST be set to 00 8 . | +| Last fragment indicator | 1 byte | 00 16 – 01 16 | The LSB indicates whether the frame is the last fragment.
1 – Last fragment
0 – Not last fragment
If the message is not fragmented, the value MUST be set to 1.
Bits 1-7 are reserved. Set to zero on transmission. Ignore upon reception. | +| TLVs | 35-1489 bytes | See Table A.3 | One or more concatenated TLV-formatted data elements (primitives). Each TLV has a format shown in Table A.3. | +| End TLV | 3 bytes | 000000 16 | Indicates the end of the TLV message | + +The format of the TLVs to be used for communication of the messages in this Recommendation is defined in Table A.3. The defined TLV format is consistent with the ITU-T vendor specific TLV, as defined in clause 11 of [ITU-T G.9979] and with the IEEE 1905 vendor specific TLV as defined in Table 6-7 of [IEEE 1905.1]. All TLVs defined to convey the primitives in this Recommendation are identified by the vendor specific TLV-type = 0B16. The TLV-length field carries a 2-byte unsigned integer indicating the length of the TLV-value field in bytes. The TLV-value field consists of four sub-fields: + +- a 3-byte sub-field with the ITU-T OUI; +- a 1-byte sub-field with the ITU-T subtype. It shall be fixed to the value 0016; +- the last two sub-fields correspond to the ITU-T TLV payload, see clause 11 of [ITU-T G.9979], containing a 2-byte ITU-T G.9977 OPCODE and a m-byte field containing the ITU-T G.9977 message body, as defined in clause 7.6. + +**Table A.3 – TLV format** + +| Field | Length | Value range | Description | +|------------|---------|-----------------------------------------|-------------------------------------------------------------------------------------------------------------| +| TLV-Type | 1 byte | 0B 16 | Vendor specific TLV | +| TLV-Length | 2 bytes | 0006 16 – FFFF 16 | Total number of bytes in TLV-Value field (Note 1) | +| TLV-Value | 3 bytes | 0019A7 16 | ITU-T OUI (the 24-bit globally unique IEEE-SA assigned value for ITU-T) | +| | 1 byte | 00 16 | ITU-T TLV subtype corresponding to ITU-T G.9977 messages. It shall be fixed to the value 00 16 . | +| | 2 bytes | 0000 16 – FFFF 16 | The primitive type (OPCODE); the particular OPCODE types are defined in Table 7-5 (Note 2) | +| | m bytes | N/A | Parameters of the primitive as defined in corresponding tables of clause 7.6 (Note 2) | + +NOTE 1 – the value of the length field shall be in the range 32-1486 bytes. +NOTE 2 – The OPCODE and parameters (m+2 bytes) of the TLV-Value field correspond to the message content (n bytes) of the ITU-T vendor specific message as defined in Table 11-1 of [ITU-T G.9979]. + +# Bibliography + +- [b-ITU-T G.9700] Recommendation ITU-T G.9700 (2014), *Fast access to subscriber terminals (G.fast) – Power spectral density specification.* +- [b-ITU-T G.9960] Recommendation ITU-T G.9960 (2015), *Unified high-speed wireline-based home networking transceivers – System architecture and physical layer specification.* +- [b-ITU-T G.9964] Recommendation ITU-T G.9964 (2011), *Unified high-speed wireline-based home networking transceivers – Power spectral density specification.* +- [b-BBF TR-069] Broadband Forum TR-069 Amendment 5 (2013), *CPE WAN Management Protocol*, November. +<[https://www.broadband-forum.org/technical/download/TR-069\\_Amendment-5.pdf](https://www.broadband-forum.org/technical/download/TR-069_Amendment-5.pdf)>h +- [b-BBF TR-181] Broadband Forum TR-181 Issue 2, (2010), *Device Data Model for TR-069*, May. +<> + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.998.1-200501-I_PDF-E/raw.md b/marked/G/T-REC-G.998.1-200501-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..f267f7dfe9fb495fadc00b28e990f00edbf93b67 --- /dev/null +++ b/marked/G/T-REC-G.998.1-200501-I_PDF-E/raw.md @@ -0,0 +1,1041 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.998.1** + +(01/2005) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Access networks + +# --- **ATM-based multi-pair bonding** + +ITU-T Recommendation G.998.1 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.998.1** + +# **ATM-based multi-pair bonding** + +## **Summary** + +This Recommendation describes a method for bonding of multiple digital subscriber lines (DSL) to transport ATM streams. The specifications of this Recommendation provide a complete description of startup, operational, and contingency modes of operation which allows for interoperability between vendors. + +This Recommendation includes the following types of requirements, recommendations, and information for defined DSL systems, including: + +- higher-layer transport-independent requirements; +- higher-layer transport-dependent, e.g., ATM, requirements. + +## **Source** + +ITU-T Recommendation G.998.1 was approved on 13 January 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2005 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +| | | Page | +|------|-----------------------------------------------------------------------------------------|------| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Overview ..... | 4 | +| 6 | Mode of operation..... | 5 | +| 6.1 | Sequencing payload traffic ..... | 5 | +| 6.2 | Bonding Group ID (GID) and Management Entity (ME) ..... | 5 | +| 6.3 | Autonomous Status Messages (ASMs) ..... | 6 | +| 6.4 | Link eligibility and link activation ..... | 6 | +| 6.5 | Measurement of bonding group differential delay ..... | 8 | +| 6.6 | Compensation of differential delay by the CPE transmitting entity..... | 8 | +| 7 | Reference models..... | 9 | +| 7.1 | User plane protocol reference model..... | 9 | +| 7.2 | Bonding sublayer in layer reference model..... | 10 | +| 7.3 | Functional reference model ..... | 10 | +| 8 | Cell header formats..... | 11 | +| 8.1 | Autonomous Status Messages (ASM) ..... | 11 | +| 8.2 | Idle and unassigned cells ..... | 11 | +| 8.3 | OAM and ATM payload cells ..... | 11 | +| 8.4 | HEC errors..... | 11 | +| 9 | Bonding group internal control protocol ..... | 11 | +| 9.1 | Types of control message ..... | 11 | +| 10 | Initialization..... | 18 | +| 11 | External management ..... | 20 | +| 11.1 | OAM interface primitives..... | 20 | +| 11.2 | OAM channel between NMS and bonding entity ..... | 21 | +| 11.3 | Cell rate adjustment..... | 21 | +| 11.4 | MIB elements ..... | 22 | +| | Appendix I – Optional initialization procedure facilitating spectral optimization ..... | 23 | +| | Appendix II – Sample initialization for the ATM bonding protocol ..... | 24 | +| | Appendix III – Link status state machine ..... | 26 | +| | Appendix IV – Example of algorithm to derive the end-to-end delay..... | 27 | +| | BIBLIOGRAPHY ..... | 28 | + + + +# ATM-based multi-pair bonding + +# 1 Scope + +The purpose of this Recommendation is to assist manufacturers, providers, and users of products on how to use multiple DSL lines to carry a single ATM payload stream. In order to satisfy this purpose, requirements and guidelines are provided. This Recommendation is written to satisfy the following bonding objectives: + +- 1) bonding shall support dynamic removal and restoration of pairs without human intervention; +- 2) bonding shall support disparate data rates, up to a ratio of 4-to-1 (fastest to slowest), amongst its pairs; +- 3) the protocol shall allow bonding of 2-32 pairs; +- 4) the protocol shall permit bonding of randomly assigned ports on an access node; +- 5) the protocol shall be PHY independent; +- 6) the protocol shall incur a maximum overall one-way bonding delay of 2 ms. + +In order for implementations compliant to this Recommendation to be interoperable between vendors, an initialization procedure, a payload tagging method, and OAM capability are provided. + +The applications supported within this Recommendation relate to bonding of multiple DSL loops to deliver ATM payload beyond the rate/reach capability of a single DSL loop. Each ATM TPS-TC (assuming multiple bearer channels) shall operate in an independent bonded group. As described within this Recommendation, the customer premises equipment (CPE) represents the User-Network Interface (UNI) to the ATM network. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation + +- [1] ITU-T Recommendation G.992.3 (2005), *Asymmetric digital subscriber line transceivers2 (ADSL2)*. +- [2] ITU-T Recommendation G.994.1 (2003), *Handshake procedures for digital subscriber line (DSL) transceivers*. +- [3] ITU-T Recommendation G.997.1 (2003), *Physical layer management for digital subscriber line (DSL) transceivers*. +- [4] ITU-T Recommendation I.363.5 (1996), *B-ISDN ATM Adaptation Layer specification: Type 5 AAL*. + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 carrier:** An organization that provides telecommunications services to customer installations. + +**3.2 central office:** In this Recommendation, the telephone building that is the origin of the outside loop plant. + +**3.3 customer installation:** All cabling and equipment on the customer side of the network interface. + +**3.4 customer premises equipment:** Telecommunications equipment located at the customer installation on the customer side of the network interface. For the purposes of this Recommendation, it is defined as multiple receivers that aggregate traffic from multiple lines into one ATM stream. + +**3.5 downstream:** The direction of transmission from the carrier central office to the customer installation. + +**3.6 Inverse Multiplexing over ATM (IMA):** IMA is used in this Recommendation to refer to ATM Forum specifications, not the bonding method of this Recommendation. + +**3.7 loop:** A communication path between the distributing frame in a carrier central office and the network interface at a customer location. + +**3.8 network:** All equipment and facilities, including loop plant, located on the carrier side of the network interface. + +**3.9 network interface:** The physical demarcation point between carrier network loop facilities and the CI. + +**3.10 pair:** Two insulated conductors. + +**3.11 showtime:** A mode of operation of DSL modems that corresponds to transmission of live user data. It follows as a last step after all initialization and retraining procedures. + +**3.12 upstream:** The direction of transmission from the customer installation to the carrier Central Office. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations: + +| | | +|--------|----------------------------------------------| +| AAL 5 | ATM Adaptation Layer 5 | +| ADSL | Asymmetric Digital Subscriber Line | +| ANSI | American National Standards Institute | +| ASM | Autonomous Status Message | +| ATM | Asynchronous Transfer Mode | +| ATM-TC | ATM Transmission Convergence (sublayer) | +| CAC | Connection Admission Control | +| CI | Customer Installation (see definition) | +| CLP | Cell Loss Priority | +| CO | Central Office (see definition) | +| CPE | Customer Premises Equipment (see definition) | + +| | | +|--------|----------------------------------------------------------------------------------------------------------------------------------| +| CRC | Cyclic Redundancy Check | +| DS | Downstream | +| DSL | Digital Subscriber Line | +| FE | Far End | +| GID | Group Identifier | +| GFC | Generic Flow Control | +| HEC | Header Error Control | +| ICP | IMA Control Protocol (cell) | +| IMA | Inverse Multiplexing over ATM (see definition) | +| ITU-T | International Telecommunication Union – Telecommunication Standardization Sector | +| ME | Management Entity | +| MIB | Management Information Base | +| ms | Millisecond | +| NE | Near End | +| NI | Network Interface (see definition) | +| NMS | Network Management System | +| OAM | Operations, Administration and Maintenance | +| PHY | Physical layer | +| PMD | Physical Media Dependent (sublayer) | +| PMS-TC | Physical Media-Specific Transmission Convergence (sublayer) | +| PTI | Payload Type Identifier | +| Rx | Receive | +| SAR | Segmentation And Reassembly | +| SID | Sequence Index | +| SNMP | Simple Network Management Protocol | +| TPS-TC | Transport Protocol Specific – Transmission Convergence (sublayer) | +| TU-C | Transceiver Unit – Central office end. Sometimes combined with another letter; e.g., ATU-C for a central office ADSL transceiver | +| TU-R | Transceiver Unit – Remote terminal end. Sometimes combined with another letter; e.g., ATU-R for a remote ADSL transceiver | +| Tx | Transmit | +| UNI | User-Network Interface | +| US | Upstream | +| UTOPIA | Universal Test and Operations PHY Interface for ATM | +| VC | Virtual Channel | +| VCI | VC Identifier | +| VP | Virtual Path | + +# 5 Overview + +An illustration of the bonding system for transport of an ATM payload across several DSL lines with disparate data rates is provided in Figure 1 below. In traditional inverse multiplexing over ATM (IMA) as specified in the ATM Forum document, Inverse Multiplexing for ATM (IMA) Specification, Version 1.1 [B1], it is assumed that all bonded links operate at the same nominal rate. The original cells are not modified, and control (ICP) cells are inserted for OAM communication between the two ends. In this Recommendation, each cell is tagged with a Sequence ID (SID). The transmitter may place any cell on any link, and the receiver can reassemble the original sequence. + +![Figure 1/G.998.1 – Status message flow. The diagram shows two main entities: 'CO' side on the left and 'CPE' side on the right. Each side has a 'Transmitting entity' and a 'Receiving entity'. On the CO side, the Transmitting entity sends 'Bonded links (downstream direction)' to the CPE's Receiving entity. The Receiving entity on the CO side receives 'Bonded links (upstream direction)' from the CPE's Transmitting entity. Status messages are shown: 'CO-side status messages' (blue arrow) from CO Receiving to CO Transmitting, and 'CPE-side status messages' (purple arrow) from CPE Transmitting to CPE Receiving. External 'Aggregate connection' labels are present on both sides.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg) + +Figure 1/G.998.1 – Status message flow. The diagram shows two main entities: 'CO' side on the left and 'CPE' side on the right. Each side has a 'Transmitting entity' and a 'Receiving entity'. On the CO side, the Transmitting entity sends 'Bonded links (downstream direction)' to the CPE's Receiving entity. The Receiving entity on the CO side receives 'Bonded links (upstream direction)' from the CPE's Transmitting entity. Status messages are shown: 'CO-side status messages' (blue arrow) from CO Receiving to CO Transmitting, and 'CPE-side status messages' (purple arrow) from CPE Transmitting to CPE Receiving. External 'Aggregate connection' labels are present on both sides. + +**Figure 1/G.998.1 – Status message flow. Each transmission direction is treated independently** + +A bonding group is defined as a bidirectional ATM stream transported by multiple bidirectional bearers across multiple physical media in both upstream and downstream directions.1 A single bonding group cannot span multiple CPE entities or CO-side access nodes. As a consequence, the control channel is also a bidirectional ATM stream, consisting of ATM messages called Autonomous Status Messages (ASMs). The content and sequence of these messages defines a control protocol between the two bonding entities in both directions. Some implementations may support multiple bearers on each physical link. Different bearers on the same line shall never be bonded together into the same group. + +The control protocol communicates the status of each link in the bonding group. The way a bonding group is defined at startup, maintained during operation, and put out of service is discussed below. + +The underlying bit rate of the individual links within a bonded group may be freely and independently changed by their respective PHY layers.2 It is the responsibility of the transmitter not to overrun PHY transmit buffers, nor add delay created by excess buffering (by either carefully controlling the PHY bit rate itself, by allowing the PHY bit rate to "float" and then honoring back pressure, or by monitoring instantaneous bit rate and rate shaping its transmissions, matching multiplex ordering to rates, etc.). + +1 It should be noted that the upstream and downstream rates may be different. + +2 Resultant changes in bit rate are subject to constraints of buffer size, number of lines, and differential delay. The 4-to-1 ratio is not a hard limit, and may be violated provided these other constraints are satisfied. + +# 6 Mode of operation + +## 6.1 Sequencing payload traffic + +The method for bonding ATM paths defined in this Recommendation is to tag each ATM cell with an 8-bit or 12-bit Sequence Index (SID)3,4, which is done by replacing bits in the ATM header with SID bits between bonding entities and, depending on implementation, may recalculate the HEC. Although cells may be transmitted along paths with different delays, changing bit rates, and non-stationary delays, receivers can temporarily store incoming cells and use the SID to determine their original order. + +Within the group, the SID increments consecutively from '0' through '255' (8-bit SID) or '0' through '4095' (12-bit SID), and wraps around to '0' again. After assembling the aggregate cell stream, these SID bits are replaced with zeros at the receiver. A transmitter shall never skip any of the sequence indices in this sequence. + +The ATM cell header mappings are shown in Figure 2. CPE shall support all configurations. The CO may support either (or both) formats, but only one format shall be used in any given bonded group. + +![](7e670a2b556b53ea9002dfff3a420e08_img.jpg) + +| | | | | | | +|-----|-------------------|--------------------|-----|-----|-------------------| +| GFC | VPI
(bits 7:0) | VCI
(bits 15:0) | PTI | CLP | HEC
(bits 7:0) | +|-----|-------------------|--------------------|-----|-----|-------------------| + +a) Standard ATM cell header + +| | | | | | | | +|--------------------|-------------------|-------------------|-------------------|-----|-----|-------------------| +| SID
(bits 11:8) | VPI
(bits 7:0) | SID
(bits 7:0) | VCI
(bits 7:0) | PTI | CLP | HEC
(bits 7:0) | +|--------------------|-------------------|-------------------|-------------------|-----|-----|-------------------| + +b) Modified ATM cell header for use with 12-bit SID + +| | | | | | | | +|-----|-------------------|-------------------|-------------------|-----|-----|-------------------| +| GFC | VPI
(bits 7:0) | SID
(bits 7:0) | VCI
(bits 7:0) | PTI | CLP | HEC
(bits 7:0) | +|-----|-------------------|-------------------|-------------------|-----|-----|-------------------| + +c) Modified ATM cell header for use with 8-bit SID + +G.998.1\_F02 + +Figure 2/G.998.1 – Standard and modified ATM cell headers + +## 6.2 Bonding Group ID (GID) and Management Entity (ME) + +As shown in Figure 1, each side of a bonding group has a transmitting and a receiving entity. The bonding group operating from the Central Office (CO) side towards the Customer Premises Equipment (CPE) side has a unique Group ID (GID) assigned by the CO bonding management entity (bonding ME). The corresponding bonding group operating from the CPE side towards the CO side shall use the same GID (by definition), which it dynamically learns during initialization. All links within a bonding group shall use the same group ID in both the upstream and downstream directions. The ME also assigns the Tx link number to each of the links in the bonding group. The + +3 In this Recommendation, 8 and 12 bits of sequence index space have been defined. Note that the use of a particular SID is bounded by the aggregate rate, differential delay, and number of links. Implementations are not compelled to provide buffer space to accommodate the full range of sequence indices and are free to provide a sufficient but smaller number of buffers to suit their target application. + +4 Implementations should equalize latency on each link. However, when bonding DSL types that may have different latencies due to different values in PHY layer parameters, implementations should be able to tolerate at least 4 ms of differential delay. Differences in electrical length will not contribute significantly to the differential delay. No additional buffer is required for this variation. + +Tx link numbers are assigned at the CO side and the CPE side will dynamically learn the Tx link numbers during initialization. + +## 6.3 Autonomous Status Messages (ASMs) + +Each bonding group has an associated set of Autonomous Status Messages (ASMs) with a unique GID that is used to communicate the status of the links in the group in each direction. These ASMs are used for both startup and maintenance of the links in a bonding group as defined in this clause. + +Autonomous status messages shall always be transmitted onto all links within the group which have been provisioned. These messages shall be transmitted regularly on the available links with the Tx link number set to the number assigned to the physical link (line number and bearer number) on which the message is to be carried. During initialization, ASM transmission shall occur on each and every link in a group. + +Receiver implementations shall always accept and rely upon non-errored autonomous status messages received on any incoming link that has a far-end Tx link status of 'Acceptable to carry bonded traffic' or 'Selected to carry bonded traffic' as defined in Table 3. + +## 6.4 Link eligibility and link activation + +The receiving entity is primarily responsible for determining which links are eligible to become active in the transmit group. In order to be eligible, a link shall be both: + +- a) of sufficient quality; and +- b) determined by the receiver to be required at that time. + +The receiver notifies the far-end transmitting entity using ASMs with the provisioned group ID with Rx link status of 'Acceptable to carry bonded traffic' as defined in Table 3. In all cases, a receiving entity should identify and count all HEC errors and consider all HEC errors in determining whether a link is suitable for inclusion within the active group or not. An implementation should not rely solely upon receipt of autonomous status messages to flag the link state as being acceptable5, nor should an implementation rely solely upon the indication of a valid frame from the PHY layer6,7. + +When receiving an autonomous status message which indicates that a particular link has gone bad (Rx link status is 'Should not be used'), the transmitter should reconfigure itself to stop sending payload traffic on the broken link. However, the transmitter should continue sending autonomous status messages on all provisioned links, including the failed links, at the nominal rate. When receiving an autonomous status message which indicates the Rx link status is 'Acceptable to carry bonded traffic' and the link in question is currently not carrying bonded traffic, it is up to the transmitter implementation whether to use this link or not. + +The transmitting entity is not bound to activate all links which have been flagged as eligible by the receiver. The transmitter may not activate a link which the receiver has not flagged by setting the + +--- + +5 High-speed links will generally contain a very low proportion of control messages relative to payload messages. Basing link state on control messages alone could cause a high error rate to go unnoticed for an unacceptably long period. + +6 A simple network misconfiguration should be anticipated and tolerated. Although the PHY layers will each report valid incoming signals with potentially minimal errors, receiver implementations which do not authenticate the source of the ASM and disregard misconfigured links may experience complete loss of the bonding service. + +7 When DSL lines serving two different customers are inadvertently swapped, the PHY layers may not recognize the problem. In this case, receiver implementations should note the mismatch in group ID fields and take appropriate action. + +Rx link status of 'Acceptable to carry bonded traffic' as defined in clause 9.8 Bonded traffic shall be sent on a link only if the Tx link status and Rx link status are 'Selected to carry bonded traffic'. + +### 6.4.1 Adding traffic to a provisioned link + +The ASM transactions for adding bonded traffic to a link which is provisioned to be in the bonded group and not carrying bonded traffic is provided in Table 1. The traffic receiver sets Rx link status in its outgoing ASMs, and the traffic transmitter sets Tx link status in its outgoing ASMs. Also provided in the table is the action which should result. + +**Table 1/G.998.1 – Adding traffic to a provisioned link** + +| Receiver; Rx link status | Transmitter; Tx link status | Resulting action | +|---------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------|-----------------------------------| +| | Signal Rx candidate links to monitor; 'Acceptable to carry bonded traffic' | Rx monitors this link | +| When quality sufficient and Rx desires traffic on this link; 'Acceptable to carry bonded traffic' | | Tx knows it can use this link | +| | If Tx desires to use this link; 'Selected to carry bonded traffic' | Tx awaits response from Rx | +| Confirm ready to receive bonded traffic; 'Selected to carry bonded traffic' | | Bonded traffic flows on this link | + +### 6.4.2 Receiver-directed procedure to stop sending traffic + +When a receiver determines that traffic should not be sent on a link in a given direction (for a reason such as insufficient quality), the following ASM transaction can be used to configure the transmitter so that no traffic is sent on this link: + +- Rx sets Rx link status to 'Should not be used'. +- Far-end Tx should immediately stop sending traffic on that link, and should set Tx link status to 'Acceptable to carry bonded traffic' (or 'Should not be used' if it does not want Rx to consider this link again). +- The far-end Tx should continue to send ASM cells. +- Traffic may resume on this link by following the procedure outlined in Table 1. + +While it is unclear why a receiver would need to change the status of a link from Selected to Acceptable, such a transition is not precluded. Specifically, a receiver with Rx link status of '11' may change Rx link status to '10'. In this event, the transmitter shall stop forwarding payload cells on this link. The transmitting entity shall keep its Tx link status as '11' ('Selected to carry bonded traffic'). Payload traffic may not resume until the Rx link status is '11' ('Selected to carry bonded traffic'). + +8 There is no requirement that link usage is identical in both directions. If link quality is such that it is not used to carry traffic in one direction, it may still carry traffic in the other direction. + +### 6.4.3 Transmitter-directed procedure to stop sending traffic + +If a transmitter determines that a link should not be used in a given direction (because capacity not needed or other reasons at the discretion of the transmitter), the following ASM transaction can be used to inform the receiver that no traffic will be sent on this link. + +- Tx sets Tx link status to 'Should not be used', and does not send bonded traffic on this link. +- Rx should change Rx link status to 'Should not be used'. Rx will not consider adding this link back to the group until Tx changes Tx link status to 'Acceptable to carry bonded traffic'. +- Traffic may resume on this link by following the procedure outlined in Table 1. + +Note that at any point the transmitter can stop using any link to carry payload data without signalling this to the far end. + +While it is unclear why a transmitter would need to change the status of a link from Selected to Acceptable, such a transition is not precluded. Specifically, a transmitter with Tx link status of '11' may change Tx link status to '10'. In this event, the transmitter shall stop forwarding payload cells on this link prior to the transition. As a result, the receiving entity shall set its Rx link status to '10' ('Acceptable to carry payload traffic'). + +## 6.5 Measurement of bonding group differential delay + +In order to evaluate the differential delay between provisioned links, the CO and CPE ATM bonding functions shall maintain a local clock in 0.1 ms unit. The frequency offset between both clocks shall be lower than 200 ppm. The transmitter entity shall include a timestamp with the value of its local clock inside each ASM cell before transmission on a provisioned link. The timestamp format is defined in clause 9. An example algorithm to derive the differential delay from this timestamp is described in Appendix IV. + +## 6.6 Compensation of differential delay by the CPE transmitting entity + +To reduce the buffer requirement at the CO side, the CPE transmit entity shall be able to implement variable delays on a link basis between the SID tagging and the transmission through the gamma interface. The ASM cell shall incur an identical delay between the insertion of the timestamp and the transmission through the gamma interface as shown in Figure 3. At initialization or reconfiguration of the bonding group, the variable delays shall be set to 0 ms. The CO may request the CPE to implement a delay on a specific link. The value of this requested delay shall be indicated in the ASM cell transmitted on this link. To keep track of the delay compensation, the transmitter shall indicate in the ASM cell the actual delay implemented on this link. + +Buffer space is required to minimize differential delay. In the worst case, this buffer is required on all lines except one. For an ADSL upstream transmitter, a buffer space of at least 8 kbytes per line shall be provided.9 This is based on the ability to compensate for 20 ms differential delay at 3 Mbit/s. The compensation shall be implemented with a precision of at least 0.5 ms. + +Note that resultant maximal differential delay in the upstream direction should be at most 1 ms, excluding ATM and other transmission delays, if all requested compensations can be implemented by the CPEs. + +The buffer space and precision required to bond other DSL varieties is for further study. + +--- + +9 For an ADSL downstream receiver, the amount of buffering needed depends on the application and is not herein specified. + +![Figure 3/G.998.1 – Differential delay compensation in transmitter by variable delays. The diagram illustrates the process of compensating for differential delays across multiple links. Incoming ATM traffic enters an ATM bonding sequencer. The sequencer distributes traffic into multiple variable delay queues. These queues feed into Link 0 (delay x), Link 1 (delay y), and Link n (delay z). An ATM bonding control block manages the process via 'Link queuing delays control' and 'ASM injection' signals. A reference point gamma is indicated at the output of the queues.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +``` + +graph LR + Traffic[Incoming ATM traffic] --> Sequencer[ATM bonding sequencer] + Control[ATM bonding control] -- Link queuing delays control --> Queues + Control -- ASM injection --> Sequencer + Sequencer --> Queues[Variable delay queues] + Queues --> L0[Link 0 - delay x] + Queues --> L1[Link 1 - delay y] + Queues --> Ln[Link n - delay z] + +``` + +Figure 3/G.998.1 – Differential delay compensation in transmitter by variable delays. The diagram illustrates the process of compensating for differential delays across multiple links. Incoming ATM traffic enters an ATM bonding sequencer. The sequencer distributes traffic into multiple variable delay queues. These queues feed into Link 0 (delay x), Link 1 (delay y), and Link n (delay z). An ATM bonding control block manages the process via 'Link queuing delays control' and 'ASM injection' signals. A reference point gamma is indicated at the output of the queues. + +**Figure 3/G.998.1 – Differential delay compensation in transmitter by variable delays** + +# 7 Reference models + +## 7.1 User plane protocol reference model + +An ATM bonding group is a bidirectional ATM stream transported by multiple bearers across multiple physical media in both upstream and downstream directions. The bonding layer has the capability to manage multiple bonding groups. A DSL bearer channel shall only belong to one bonding group at a given time. Multiple VC and VP connections can be supported in one bonding group subject to constraints of available VPI/VCI space supported in the modified cell header. + +Figures 4 and 5 show the user plane protocol reference models of one bonded group and multiple bonded groups, respectively, that are consistent with the representation used in xDSL Recommendations. The bonding sublayer is located between the ATM transport layer and xDSL transceiver's ATM-TC sublayer. + +![Figure 4/G.998.1 – User plane protocol reference model of one bonded group. The diagram shows two protocol stacks for CO (Central Office) and CPE (Customer Premises Equipment). Both stacks have 'ATM transport protocol' and 'ATM bonding protocol' at the top. Below these are 'ATM-TC', 'PMS-TC', 'PMD', and 'PHY' layers. The CO stack has a gap between the two ATM-TC layers. The CPE stack also has a gap between its two ATM-TC layers. The interfaces between the stacks are labeled gamma_C at the CO and gamma_R at the CPE.](9ae17964ddd9b814c7d905b1af2fddf2_img.jpg) + +CO + +| | | | +|------------------------|--|--------| +| ATM transport protocol | | | +| ATM bonding protocol | | | +| ATM-TC | | ATM-TC | +| PMS-TC | | PMS-TC | +| PMD | | PMD | +| PHY | | PHY | + + $\gamma_C$ + +CPE + $\gamma_R$ + +| | | | +|------------------------|--|--------| +| ATM transport protocol | | | +| ATM bonding protocol | | | +| ATM-TC | | ATM-TC | +| PMS-TC | | PMS-TC | +| PMD | | PMD | +| PHY | | PHY | + +Figure 4/G.998.1 – User plane protocol reference model of one bonded group. The diagram shows two protocol stacks for CO (Central Office) and CPE (Customer Premises Equipment). Both stacks have 'ATM transport protocol' and 'ATM bonding protocol' at the top. Below these are 'ATM-TC', 'PMS-TC', 'PMD', and 'PHY' layers. The CO stack has a gap between the two ATM-TC layers. The CPE stack also has a gap between its two ATM-TC layers. The interfaces between the stacks are labeled gamma\_C at the CO and gamma\_R at the CPE. + +**Figure 4/G.998.1 – User plane protocol reference model of one bonded group** + +![Figure 5/G.998.1 – User plane protocol reference model of multiple bonded groups. The diagram shows two stacks of protocol layers for CO (Central Office) and CPE (Customer Premises Equipment). Each stack has a dashed box at the top labeled 'ATM transport protocol'. Below it is 'ATM bonding protocol'. The next layer is 'ATM-TC', followed by 'PMS-TC', 'PMD', and 'PHY'. In the CO stack, there are two 'ATM-TC' and 'PMS-TC' blocks with an ellipsis between them. Arrows labeled 'Group 1' and 'Group 2' point to the 'PHY' and 'ATM-TC' layers respectively. A label 'γc' is on the right of the CO stack and 'γr' is on the left of the CPE stack. The text 'G.998.1_F05' is at the bottom right.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Figure 5/G.998.1 – User plane protocol reference model of multiple bonded groups. The diagram shows two stacks of protocol layers for CO (Central Office) and CPE (Customer Premises Equipment). Each stack has a dashed box at the top labeled 'ATM transport protocol'. Below it is 'ATM bonding protocol'. The next layer is 'ATM-TC', followed by 'PMS-TC', 'PMD', and 'PHY'. In the CO stack, there are two 'ATM-TC' and 'PMS-TC' blocks with an ellipsis between them. Arrows labeled 'Group 1' and 'Group 2' point to the 'PHY' and 'ATM-TC' layers respectively. A label 'γc' is on the right of the CO stack and 'γr' is on the left of the CPE stack. The text 'G.998.1\_F05' is at the bottom right. + +**Figure 5/G.998.1 – User plane protocol reference model of multiple bonded groups** + +## 7.2 Bonding sublayer in layer reference model + +Table 2 shows the bonding sublayer's layer reference model. + +**Table 2/G.998.1 – ATM bonding in layer reference model** + +| | User plane functions | Layer management functions | Plane management functions | +|------------------------|-----------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| xDSL ATM bonding layer |
  • ATM cell stream split and reconstruction
  • ASM cell transmit and receive
|
  • ASM handling
|
  • Group configuration and removal
  • Group dynamic link management
  • Group rate change
  • Group status update
  • Group performance and fault monitoring
| + +## 7.3 Functional reference model + +Figure 6 illustrates the main functional blocks of the ATM bonding entity. + +![Figure 6/G.998.1 – ATM bonding functional blocks. The diagram shows functional blocks for CO and CPE connected by 'Bonding groups'. The CO block contains 'ATM interface', 'ATM bonding', and 'Bonding management'. The CPE block contains 'ATM bonding', 'ATM interface', and 'Bonding management'. Double-headed arrows connect the 'ATM bonding' blocks of CO and CPE, with an ellipsis between them. The text 'G.998.1_F06' is at the bottom right.](b90144cfbb81a2d610d920240fda689d_img.jpg) + +Figure 6/G.998.1 – ATM bonding functional blocks. The diagram shows functional blocks for CO and CPE connected by 'Bonding groups'. The CO block contains 'ATM interface', 'ATM bonding', and 'Bonding management'. The CPE block contains 'ATM bonding', 'ATM interface', and 'Bonding management'. Double-headed arrows connect the 'ATM bonding' blocks of CO and CPE, with an ellipsis between them. The text 'G.998.1\_F06' is at the bottom right. + +**Figure 6/G.998.1 – ATM bonding functional blocks** + +### 7.3.1 ATM interface + +The ATM interface block provides a bidirectional ATM connection to the higher ATM transport layer. In each direction, multiple ATM streams can be supported. + +### 7.3.2 ATM bonding function + +For the transmit direction in a bonding group, the ATM-bonding function block controls cell distribution onto member ATM-TC bearers that may have different net data rates, and places proper sequence IDs into the cells to allow recovery of cell sequencing at the receiver. In the receive direction, the function block merges cells received from the member bearers in the order defined by the sequence ID and reconstructs the original ATM stream. + +Other than handling regular ATM cell streams, the block also handles proper transmission and reception of ASM cells on a per-group basis. + +### **7.3.3 Bonding management function** + +The main function of the management block is to set up and remove bonding groups, as well as to manage the bonding group's operational behaviours, such as dynamic link drop/recovery, etc. The management block also monitors the group performance and fault conditions. In addition, the block does ASM message handling. + +# **8 Cell header formats** + +## **8.1 Autonomous Status Messages (ASM)** + +The protocol for controlling the bonded links is carried in single-cell messages (autonomous status messages). These cells shall be addressed as if they originate from VP=0, VC=20. ASMs are not sequenced in the same manner as regular payload traffic. The sequence index bits should be set to '00' in all control cells. + +Refer to the description of the autonomous status message format in clause 9. + +## **8.2 Idle and unassigned cells** + +Idle and unassigned cells, as defined in ITU-T Recs I.432.1 and I.361, are handled normally by the ATM-TC of the transceiver. They are neither seen nor generated by the bonding layer. + +## **8.3 OAM and ATM payload cells** + +A bonding group is logically the same as a single path for the purposes of ATM traffic. The treatment of OAM and ATM payload cells on a bonded group shall follow the same rules as if those cells were carried on a single path carrying multiple ATM streams. + +## **8.4 HEC errors** + +It is important for the bonding control entity to identify, count, and respond to all HEC errors. HEC errors may occur within ATM payload, bonding control, idle, unassigned, and OAM cells. HEC errors shall be considered when determining whether a link is suitable for inclusion within the active group or not. How HEC errors are communicated to the bonding layer is left to the implementation. + +# **9 Bonding group internal control protocol** + +## **9.1 Types of control message** + +The control protocol outlined in this Recommendation consists of single message type: an autonomous status message. This message conveys the status of the links to the far-end bonding management entity. + +### **9.1.1 Length and format of control messages** + +The status message is contained in a single ATM cell, and bytes 50-53 are used to carry a CRC-32 on the payload of this cell. Bytes 46-49 are defined so that the ASM has the form of a single-cell AAL 5 message. An AAL 5 SAR is not required for compliance to this Recommendation. + +### 9.1.2 Priority of control messages + +It is the responsibility of the transmitter implementation to determine when to schedule and transmit control messages. The policy of when to insert a control message into the payload cell stream is left to the discretion of the implementer. + +### 9.1.3 Frequency of autonomous status messages + +During showtime, ASM messages shall be sent periodically on all provisioned links within each group. These messages are used for monitoring the status of the link and can be used by the bonding ME for dynamic link management and error control. According to implementation, ASMs may be transmitted as frequently as required. Status messages should be transmitted no less frequently than once per second per link in the bonded group. Transmitters should include means to ensure that in the long term10, control messages are not transmitted at more than 1% of the available link capacity.11 This limit does not apply during initialization. + +It is not the intention to arbitrarily rule out links which operate at very low bit rates. Receiver implementations should endeavour to accept and process all incoming control messages, regardless of their instantaneous arrival rate. In the event that a receiver implementation cannot keep up with the rate of arrival of control messages, it is free to discard messages as necessary because the control protocol has been specified in a manner which is tolerant of receiver discards. + +Transmission of status messages should be staggered across links to reduce the jitter impact upon the payload traffic. For example, if there are 32 links within a bonded group and the links are numbered from '0' to '31', status messages may be sent in a round-robin manner commencing with a message on link '0', then link '1', through to link '31' and then back to link '0' again. This would result in a bonded group of 32 links carrying at least 32 status messages every second; one status message per link. + +However, there is no strict requirement for a transmitter implementation to follow a particular sequence when choosing the order of the links on which autonomous status messages are forwarded. Implementers are free to choose any order and frequency considered appropriate for the implementation. + +Receivers should not anticipate a particular timing or order other than the minimum rate of one autonomous status message per second per link. Receivers should make allowance for the possible loss or corruption of autonomous status messages and should not base the assessment of link health on the arrival (or non-arrival) of autonomous status messages alone. + +Because large frames carried within AAL 5 payloads are adversely impacted when one of the links within a bonded group degrades, one or more autonomous status messages should be sent as soon as a receiver identifies a degraded link. This, for example, could be implemented by immediately transmitting the next autonomous status message on the next scheduled link without waiting for its associated timer to expire. + +--- + +10 It should be understood that, during initialization, ASMs may be transmitted at a frequency greater than 1%. + +11 This implies that each link should achieve a minimum allowable bit rate of 100 cells per second (42.4 kbit/s). + +### 9.1.4 Format of the autonomous status message + +The format of the autonomous status message is described in Table 3. + +**Table 3/G.998.1 – ASM message format** + +| Octet | Label | Range | Comments | +|-----------------|----------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-4 | Cell header | | VPI=0, VCI=20, PTI=1, CLP=0, GFC=0
The SID field should be set with all bits '0'. SID is not used in ASMs. | +| 5 | HEC | 0..255 | HEC calculated in the standard way across bytes 1..4 | +| 6 | Message type | 0..255 | Defines message type:
'00': Autonomous status message, 12-bit SID format
'01': Autonomous status message, 8-bit SID format
'FF': Initialization or reconfigure group | +| 7 | ASM identifier | 0..255 | Modulo 256 message identifier. Incremented from 0 through 255 and back to 0.
The field is used by the receiver to derive the age of ASMs.
The bonding ME increments the 'ASM identifier' number for each new autonomous status message sent on a per-group basis. The receiver ignores (discards) autonomous status messages having an 'ASM identifier' earlier than other recently received autonomous status messages. | +| 8
(bits 0-4) | Tx link number | 0..n-1 | This field is used for link identification. Links should be numbered sequentially commencing with '0'. | +| 8
(bits 5-6) | Reserved | | Reserved for future definition.
Shall be set to '0' in all outgoing messages.
Shall be ignored in all incoming messages. | +| 8
(bit 7) | Insufficient buffers | Boolean | This field will be used to assist operators and end users identify situations where the receiver implementation does not support sufficient buffers to bond all available links.
'0': All links flagged as available for bonding could be supported based upon current buffers, differential bit rate, differential delay, and jitter.
'1': There are insufficient buffers to allow bonding of all links currently flagged as available for bonding. | +| 9 | Number of links | 1..32 | This field indicates the number of provisioned links in the bonding group. | + +**Table 3/G.998.1 – ASM message format** + +| Octet | Label | Range | Comments | +|-------|-----------------------------------------------------|---------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 10-17 | Rx link status
(2 bits per link, up to 32 links) | 8 bytes |

The status of each of the Rx links (up to 32) in the bonded group.

The two MSBs (bits 7,6) in octet 10 correspond to the status of the first link (link '0'), the next two bits in octet 10 (bits 5,4) correspond to the status of the second link (link '1'), and so on. Octet 11 contains the status of link 4 (bits 7,6) through link 7 (bits 1,0), and similarly for octets 12-17.

'00': Not provisioned

'01': Should not be used

'10': Acceptable to carry bonded traffic

'11': Selected to carry bonded traffic

| +| 18-25 | Tx link status
(2 bits per link, up to 32 links) | 8 bytes |

The status of each of the Tx links (up to 32) in the bonded group.

The two MSBs (bits 7,6) in octet 18 correspond to the status of the first link (link '0'), the next two bits in octet 18 (bits 5,4) correspond to the status of the second link (link '1'), and so on. Octet 19 contains the status of link 4 (bits 7,6) through link 7 (bits 1,0), and similarly for octets 20-25.

'00': Not provisioned

'01': Should not be used

'10': Acceptable to carry bonded traffic

'11': Selected to carry bonded traffic

| +| 26-27 | Group ID | 2 bytes | Integer numbers to uniquely identify bonding groups. | +| 28-31 | Rx ASM status (1 bit per link, up to 32 links) | 4 bytes |

The status of ASMs received on each link in the past one second:

'0': At least 1 error-free ASM received

'1': No error-free ASMs received

| +| 32 | Group lost cells | 0..255 | Number of cells lost at the receiver bonding layer. Modulo 256. | +| 33 | Reserved | 1 byte |

Reserved for future definition.

Shall be set to '0' in all outgoing messages.

Shall be ignored in all incoming messages.

| +| 34-37 | Timestamp | $0..2^{31} - 1$ | Value of the ATM bonding function local clock expressed in 0.1 ms unit. If not supported in the CO, this value shall be set to 0 in ASM messages transmitted from the CO. The MSB is in octet 34, and the LSB is in octet 37. | +| 38-39 | Requested Tx delay | $0..2^{16} - 1$
(Note) | Requested delay in 0.1 ms unit to be implemented by the transmitter entity on the link carrying the ASM cell. This value shall be set to 0 on ASMs transmitted from the CPE. The MSB is in octet 38 and the LSB is in octet 39. | + +**Table 3/G.998.1 – ASM message format** + +| Octet | Label | Range | Comments | +|-------|-------------------|----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 40-41 | Actual Tx delay | 0..2 16 – 1
(Note) | Actual delay in 0.1 ms unit implemented by the transmitter entity on the link carrying the ASM cell. This value shall be set to 0 on ASMs transmitted from the CO. The MSB is in octet 40 and the LSB is in octet 41. | +| 42-45 | Reserved | 4 bytes | Reserved for future definition.
Shall be set to '0' in all outgoing messages.
Shall be ignored in all incoming messages. | +| 46-47 | Reserved | Shall be set to 0x00, 0x00 | These values shall be filled in by the transmitter, but may be ignored by the receiver. 12 | +| 48-49 | Length of message | Shall be set to 0x00, 0x28 | | +| 50-53 | CRC-32 | | Shall be calculated over payload octets 6-49 as defined in AAL 5. | + +NOTE – The valid range of this parameter is determined by memory available in the CPE as specified in 6.6. + +#### **Explanation of the fields:** + +**Cell header** The modified cell header format is intended to be bit-compatible with common PHY and ATM hardware devices. It is intended that devices implementing this bonding technique be able to be simply interfaced at the UTOPIA level with non-bonding aware PHY and ATM devices such as SARs, switches, traffic controllers, and the like. + +**Message type** The message type is provisioned at the CO and sent to the CPE in this field. The message type the CPE sends to the CO in this field shall be identical to the message type received from the CO. Both ends shall use the same length SID as determined by the CO and sent to the CPE in the message type field. The message type is determined during initialization and shall not be changed while the group is in service. + +The value of '00' identifies this message as an autonomous status message and that 12-bit SID is used in this bonded group. The value '01' in this field identifies this message as an autonomous status message and that 8-bit SID is used in this bonded group. The value 'FF' in this field indicates that the bonding ME shall cease forwarding payload traffic and shall reinitialize. Implementations of this version of this Recommendation should examine the message type field, and if not '00', '01', or 'FF' the message should be silently discarded. + +Implementations of future versions of this Recommendation should monitor the message type field of incoming control messages. Receipt of an autonomous status message containing a message type of '00' or '01' + +12 Note that bytes 46 and 47 correspond to the CPCS-UU and CPI bytes, as defined in AAL 5. They are set to 0. The length field, as used both here and in AAL 5, is set to 40 (decimal), or 28 (hexadecimal). + +indicates that the far end supports the 12-bit or 8-bit formats in the first version of this Recommendation, and the implementation should silently revert to the same version. + +- ASM identifier** This field defines the sequential order of autonomous status messages. The ASM identifier should increment from '00' through 'FF' and cycle back to '00'. It should be incremented for each newly transmitted autonomous status message on a per-group basis. No two consecutive autonomous status messages should be sent with the same ASM identifier, even Status Messages sent on different links within the bonded group. The receiver examines the ASM identifier field in order to identify out-of-order reception. In the event that an autonomous status message is received with an ASM identifier earlier than another recent autonomous status message, the autonomous status message with the earlier ASM identifier number should be discarded. +- Tx link number** This field denotes the number assigned to the link at the CO by the ME during initialization. The CPE learns the Tx link number for each link from the ASMs received on the link from the CO. The CPE uses the same Tx link number for its ASMs. Link number assignments shall be consecutively numbered from '0'. These numbers shall not change for the life of the group, regardless of any change in link status. The Tx link number is configured statically when the bonded group is provisioned and shall not be changed while the group is in service. +- Insufficient buffers** Before receivers may flag an Rx link as suitable for inclusion in the bonded group, it shall assess the prevailing differential bit rate, line rate, and jitter to determine the buffering requirements. If there are insufficient buffers available to support all links currently flagged as available for bonding, the receiver shall set the 'Insufficient Buffers' field to notify the far end of this condition. +- Number of links** This field describes the number of links which have been provisioned in this bonding group. This is a static field which shall not be changed during the life of the group. +- Rx link status** The most important function of the control protocol is for the two ends to be able to add links into the current group and for the two ends to be able to remove links from the group. This needs to be achieved as quickly and efficiently as possible in order to minimize lost traffic and maximize available time. Link numbers are defined by the management entity and provisioned at the CO. Two status bits are defined for each link. To convey status for 32 lines, 64 bits or 8 bytes are required. See definitions in the ASM definition. The first two bits in the first byte of the field correspond with the status of the first Rx link (link '0'). The second two bits correspond with the status of the second link (link '1') and so on through to the last two bits of the last byte which correspond with the status of the 32nd link (link '31'). + +The status indications are to be used as follows: + +- **Not provisioned:** Link indicated as not provisioned, and will never be a part of the bonded group. Note that the number of provisioned links is equal to the field 'Number of Links'. It is the same in both directions, therefore, if Tx link status is 'Not provisioned', Rx link status shall also be 'Not provisioned'. +- **Should not be used:** Transmitter should not use link for bonding but is provisioned by NMS as a candidate link member (i.e., temporary outage). If the ATM path is still present on this link, a transmitter that receives ASMs with this Rx link status shall continue to send ASMs. +- **Acceptable to carry bonded traffic:** Used to request the transmitter consider this provisioned link for bonding. +- **Selected to carry bonded traffic:** Bonded traffic expected on this link. + +Tx link status To convey status for 32 lines, 64 bits or 8 bytes are required. See definitions in the ASM definition. + +The first two bits in the first byte of the field correspond with the status of the first Tx link (link '0'). The second two bits correspond with the status of the second link (link '1') and so on through to the last two bits of the last byte which correspond with the status of the 32nd link (link '31'). + +The status indications are to be used as follows: + +- **Not provisioned:** Link indicated as not provisioned, and will never be a part of the bonded group. See 'Rx link status'. +- **Should not be used:** Receiver should not consider the link for bonding, but is provisioned by NMS as a candidate link member. +- **Acceptable to carry bonded traffic:** Used to indicate which links the receiver should consider for bonding. +- **Selected to carry bonded traffic:** Transmitter is using or will use this link to carry bonded traffic. + +During the life of a group, the status can be changed between any of the last three types. However, if the group initialized flagging a particular link as "Not provisioned", it shall never change from this indication. + +Group ID This field is configured statically when the bonded group is provisioned and shall not be changed while the group is in service. These fields may be used by an operator to help identify misconfiguration or to assist in management or debugging of the link. + +Rx ASM status This field conveys from the transmitter to the receiver whether ASMs are being received on each link. The first bit (bit 7) in the first byte of the field corresponds to the first link (link '0'). The second bit corresponds to the second link (link '1') and so on through to the last bit which corresponds with the status of the 32nd link (link '31'). + +The status indications are to be used as follows: + +- '0': At least one error-free ASM received in the past one second interval. +- '1': No error-free ASM received in the last one second interval. + +| | | +|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | This field is not valid for links with Tx link status of 'Not provisioned', as ASMs should not be expected on those links. | +| Group lost cells | This field conveys from the receiver to the transmitter the count of cells lost at the receiver bonding layer. | +| Reserved | Reserved fields should be filled with the value '0' and disregarded by the receiver. Reserved fields may be used for additional purposes in future versions of this protocol. | +| Timestamp | This field contains the value of the local clock maintained by the ATM bonding function at the transmission of the ASM cell (see 6.5). This field is required in ASMs transmitted by the CPE. If not implemented in the CO, ASMs transmitted from the CO shall set this field to 0. | +| Requested Tx delay | This field contains the value of the transmitter delay to be implemented by the transmitter on the specific link carrying this ASM cell (see 6.6). For ASMs transmitted by the CPE, this field shall be set to 0. | +| Actual Tx delay | This field contains the value of the transmitter delay implemented by the transmitter on the specific link carrying this ASM cell (see 6.6). For ASMs transmitted by the CO, this field shall be set to 0. | +| Length | Length of payload of ASM cell including reserved bytes but not CRC. Set to value 0x28 in all ASM messages. | +| CRC-32 | The value in this CRC field shall be the same as if a standard AAL 5 SAR had been used to generate the single cell status message. | + +# 10 Initialization + +There are two sides of a bonded group of links, a "CO" side and a "CPE" side. The initialization procedure is defined below: + +- 1) PHY transceivers are trained individually. When each bearer channel becomes operational, both the CO and the CPE management entities know the parameters (data rate, margin, etc.). +- 2) After the PHY enters showtime, the CO shall force its CPE peer bonding entity into an initialization state by sending an ASM with message type 'FF' and the appropriate group ID on each of the active links. If a bonding ME receives an error-free ASM with a message type of 'FF', that bonding ME shall immediately cease forwarding user payload traffic, and shall re-initialize. +- 3) The CPE bonding ME shall establish the grouping of its bearer channels into bonding groups by deriving this information from the incoming ASMs from the CO. This process is initiated by the CO bonding ME. +- 4) As soon as each PHY is in showtime, the CO bonding ME shall commence transmission of autonomous status messages with message ID other than 'FF' on the downstream links of a bonding group13. The corresponding 'Tx link status' field within the ASMs shall be set to indicate that the link is available for service but is not currently bonded. The CPE bonding ME shall remain silent on each of its links until it has received at least one error-free ASM on each provisioned link, the number of such links is equal to the 'Number of links' field in each received ASM message, and the group ID fields have the same value. + +13 When each line is carrying multiple bearers, each bearer is required to have a unique group ID. + +As the CPE bonding ME receives error-free ASMs, it uses the ASMs to learn the group ID, cell format, and the member links in the bonding group. The CPE shall commence transmission of its own ASMs on a particular link following receipt of a validated and error-free ASM on all provisioned links. + +- 5) Each bonding ME shall use the incoming 'Rx link status' indications (within the incoming ASMs from its peer) to choose which Tx links are candidates to carry payload traffic. In order for a bonding ME to commence forwarding payload traffic on a link, it shall first receive at least one error-free ASM from its peer on any of the incoming links which has the 'Rx link status' field, corresponding to the link in question, that indicates 'Selected to carry bonded traffic'. + +Neither the CO nor CPE bonding MEs are permitted to start to forward payload traffic on an outgoing Tx link until after it has received at least one ASM on that particular link. + +- 6) The CPE shall employ the upstream bearer having the same index (bearer number) as the downstream bearer on which the ASM was received. +- 7) As additional ASMs are received during the life of the group, the 'Group ID', 'Number of links' and 'Tx link number' fields should be compared with their previously received counterparts. An alarm may optionally be raised if a mismatch is noted, but in any case, forwarding of payload traffic should be interrupted and all bonded links should be placed out of service. + +After the bonding has been interrupted, the bonding MEs shall re-initialize by setting the 'Message Type' to 'FF'. + +- 8) If it is necessary for the operator to reconfigure any parameters, including a change to the 'Group ID', the CO bonding ME shall re-initialize by setting the 'Message type' to 'FF'. +- 9) If at any time a bonding ME needs to change any of its 'Rx link status' indications, it is free to do so unless otherwise constrained by another requirement in this list. Having made the change, that particular 'Rx link status' field shall not be changed again until at least three ASMs containing that change have been transmitted on each in-service Tx link. +- 10) If a bonding ME receives an error-free ASM with an 'Rx link status' field indicating that a currently in-service Tx link should not be used by the bonded group to carry bonded traffic, that bonding ME is required to cease forwarding user payload traffic on that Tx link as quickly as practical and to update its own corresponding 'Tx link status' field. +- 11) All receivers shall perform buffer requirements calculations based upon prevailing line rate, line delay, and jitter characteristics to determine whether the available buffer pool is sufficient to bond each of the links currently flagged as available for bonding. It is the receiver's responsibility to ensure that the transmitter is never permitted to bond a combination of links which could exceed the receiver's buffering capabilities. The receiver shall set the 'Insufficient buffers' field as defined in the ASM message whenever this situation is detected. + +# 11 External management + +This clause is not intended to provide a complete MIB specification for external management. + +## 11.1 OAM interface primitives + +Figure 7 shows the interface signals between the ATM bonding entity and external management functions. Each signal carries multiple primitives or parameters. + +![Diagram showing three signals (Group command, Group request, Group indicate) pointing to an ATM bonding entity box. The diagram is labeled G.998.1_F07.](58f4167687de8d7339594e5f6fbe0bc6_img.jpg) + +``` + +graph TD + GC[Group command] ---| | ATM + GR[Group request] ---| | ATM + GI[Group indicate] ---| | ATM + subgraph ATM_Entity [ ] + ATM[ATM bonding entity] + end + style ATM_Entity fill:none,stroke:#000 + style GC stroke-dasharray: 5 5 + style GR stroke-dasharray: 5 5 + style GI stroke-dasharray: 5 5 + +``` + +The diagram shows a central rectangular box labeled "ATM bonding entity". Above the box, three dashed vertical lines with diamond-shaped arrowheads point towards the box. From left to right, these lines are labeled "Group command", "Group request", and "Group indicate". The arrows for command and request point down, while the indicate arrow points both up and down. Below the box, the text "G.998.1\_F07" is written. + +Diagram showing three signals (Group command, Group request, Group indicate) pointing to an ATM bonding entity box. The diagram is labeled G.998.1\_F07. + +**Figure 7/G.998.1 – OAM interface signals** + +The group command signal passes control information to the bonding entity to create or remove bonding groups. Primitives and parameters are listed in Table 4. + +**Table 4/G.998.1 – Group command signal** + +| Primitives | Parameters | Note | +|-----------------------|------------------------------|-----------------------------------------------------------------------------------------------------------------| +| Group config/reconfig | Bonding group ID | | +| | Line number(s) | Line number + Bearer number identify a member link | +| | Bearer number(s) | | +| | Max aggregate rate | Can be set as 'infinity' to be ignored. Different elements for upstream and downstream. | +| | Min aggregate rate | Any rate achieved below min rate should fail a bonding group. Different elements for upstream and downstream. | +| | Differential delay tolerance | Covers end-to-end delay variance for aggregation buffer sizing. Different elements for upstream and downstream. | +| Group remove | Bonding group ID | | + +The group request signal is used to inquire about bonding group OAM status. Primitives are listed in Table 5. + +**Table 5/G.998.1 – Group request signal** + +| Primitives | Note | +|---------------------------|----------------------| +| Group operation inquiry | Response in Table 6. | +| Group performance inquiry | Response in Table 6. | + +The group indicate signal is used to report bonding group OAM status. Primitives and parameters are listed in Table 6. Performance measurements shall be accumulated in intervals of 15-minute and 24-hour periods. + +**Table 6/G.998.1 – Group indicate signal** + +| Primitives | Parameters | Note | +|------------------------|-------------------------|---------------------------------------------------------------------------------------------------------------| +| Group operation status | Group status | Operational, unavailable. | +| | Achieved aggregate rate | Current achieved group aggregate rate. Different elements for upstream and downstream. | +| Group performance | Group cell loss count | Cells lost at the bonding layer in the accumulation interval. Different elements for upstream and downstream. | + +Performance data for the bonded links can be derived from the MIB elements for each individual PHY as defined in ITU-T Rec. G.997.1. + +## 11.2 OAM channel between NMS and bonding entity + +Figure 8 shows an example OAM channel between an NMS and the bonding entity to pass bonding-related OAM information. In this example, SNMP is used for bonding unit management and it is transported to NT using ATM.14 Use of SNMP is not required for compliance to this Recommendation. + +![Diagram of OAM channel between NMS and bonding entity. The diagram shows an NMS (Network Management System) connected to an AN (Access Network) and a CPE (Customer Premises Equipment). The NMS contains a MIB (Management Information Base) and an SNMP (Simple Network Management Protocol) entity. The AN contains a MIB, an SNMP entity, and an ATM (Asynchronous Transfer Mode) entity. The CPE contains a MIB, an SNMP entity, and an ATM entity. Arrows indicate the flow of information: from the NMS MIB to the AN SNMP, from the AN SNMP to the AN ATM, from the AN ATM to the CPE ATM, and from the CPE ATM to the CPE SNMP. The CPE SNMP then connects to the CPE MIB. A label 'G.998.1_F08' is present at the bottom right of the diagram.](4cde160bcc69b7b6c81b648dd0e4252e_img.jpg) + +Diagram of OAM channel between NMS and bonding entity. The diagram shows an NMS (Network Management System) connected to an AN (Access Network) and a CPE (Customer Premises Equipment). The NMS contains a MIB (Management Information Base) and an SNMP (Simple Network Management Protocol) entity. The AN contains a MIB, an SNMP entity, and an ATM (Asynchronous Transfer Mode) entity. The CPE contains a MIB, an SNMP entity, and an ATM entity. Arrows indicate the flow of information: from the NMS MIB to the AN SNMP, from the AN SNMP to the AN ATM, from the AN ATM to the CPE ATM, and from the CPE ATM to the CPE SNMP. The CPE SNMP then connects to the CPE MIB. A label 'G.998.1\_F08' is present at the bottom right of the diagram. + +**Figure 8/G.998.1 – OAM channel between NMS and bonding entity** + +## 11.3 Cell rate adjustment + +After a bonding group is successfully configured/reconfigured, the achieved aggregate rate should be reported to Connection Admission Control (CAC) for connection management. During a bonding group's normal operation, the achieved aggregate rate may change due to temporary link failure/recovery. Bonding entities should report any rate change via standard interface signals. Since treatment of CAC and message passing mechanism is implementation dependent, traffic management handling necessitated by rate change is left to the discretion of implementers. + +14 Bonding MIB elements may be transported to CPE through an ATM path to enable CPE-based multi-line optimization. + +## 11.4 MIB elements + +### 11.4.1 Group provisioning + +- 1) *Group ID* + +An ID to uniquely identify a bonding group. + +- 2) *Line number* + +An ID number to uniquely identify a DSL line. + +- 3) *Bearer number* + +A bearer number as defined in ITU-T Rec. G.994.1. Combination of line number and bearer number identifies a link to bond. + +- 4) *Maximum aggregate data rate (bit/s)* + +The maximum net data rate a bonding group is allowed to achieve to carry an ATM stream. Links shall not be disabled to satisfy this parameter. Otherwise, implementation of this functionality is outside the scope of this Recommendation. If set to 'infinity', this parameter is ignored. Different elements for upstream and downstream. + +- 5) *Minimum aggregate data rate (bit/s)* + +The minimum net data rate a bonding group should achieve to carry an ATM stream. Different elements for upstream and downstream. + +- 6) *Differential delay tolerance (ms)* + +The maximum differential delay among member links in a bonding group. Different elements for upstream and downstream. + +### 11.4.2 Group performance + +- 1) *Achieved aggregate data rate (bit/s)* + +The net data rate a bonding group actually achieves. It may change subject to dynamic link usage conditions. Different elements for upstream and downstream. + +- 2) *Group status* + +Two group statuses are defined, namely operational and unavailable. A group is considered unavailable when it does not satisfy the parameters provisioned for the group. + +- 3) *Group running time* + +The accumulated time when a bonding group is in normal operation (the status is operational). Derived from group status. + +- 4) *Group Rx cell loss count* + +The total number of cells that are lost at aggregation output from a bonding group for the accumulation interval. Different elements for upstream and downstream. + +### 11.4.3 Group failures + +- 1) *Current group failure reason* + +Indicating the reason for current group failure status: Minimum data rate not met, differential delay tolerance exceeded. Implementations with other failure mechanisms can return a value of Other. + +- 2) *Group failure count* + +Count the number of times that a group is declared unavailable in the accumulation period. + +- 3) *Group unavailable seconds* + +The time in seconds during which a bonding group is unavailable in the accumulation period. + +# Appendix I + +## Optional initialization procedure facilitating spectral optimization + +Successful bonding group setup relies on careful planning and provisioning across all levels in an access system. The DSL Recommendations series (G.99x) provides sufficient procedures for an NMS to enable an ATM bonding group. The general process is outlined below15: + +- 1) Based on application requirements, derive the aggregate rate and delay variance tolerance requirement. +- 2) Select the lines to be bonded and obtain each line's DS and US rate capacities and delay information. If necessary, pre-train the candidate lines through the standard full initialization procedures, shortened/fast initialization procedures, or loop diagnostic procedures. +- 3) Process, in the NMS, the above information and develop provisioning profiles for the candidate DSL transceivers. Each provisioning profile would contain all of the necessary US/DS configuration parameters defined in ITU-T Rec. G.997.1. Among these, the min/max net data rate, minimum impulse protection16 and min/max delay17 parameters, if applicable, should be tuned to collectively reflect the bonding group's aggregate rate and delay variance tolerance requirements. +- 4) The provisioning profiles are passed to xTU-Cs. The bonding-tuned DSL configuration parameters are exchanged between xTU-Cs and xTU-Rs through the G.994.1 handshake procedure so that the DSL transceivers can be initialized in such a way as to support the bonding group's aggregate rate and delay variance requirements.18 +- 5) After the lines are up and running, the NMS issues a bonding configuration command to NE bonding entity to begin bonding initialization procedure. +- 6) If bonding initialization is successful, the bonding ME signals the system with a Group Operation Status update to be ready for ATM connections. If unsuccessful, repeat steps 1-5 with appropriate DSL configuration adjustments. + +--- + +15 This guideline is for information only, not a normative part of the Recommendation. In general, a bonding group can always be setup on already trained-up lines without any change if the resulting aggregate rate and delay variance happen to be acceptable. + +16 ITU-T Rec. G.992.3 recommends that Minimum Impulse Protection value can overrule max delay constraint when they are in conflict. + +17 ITU-T Rec. G.997.1 currently does not include MIB element for min delay. It needs to be defined. + +18 Optionally, bonding-tuned configuration parameters can also be passed to FE bonding entity through bonding OAM channel so that receiver-based multi-line joint bonding optimization can be applied to achieve better rate/power efficiency through some DSL line double-train procedure. The procedure is vendor dependent and is up to implementer's discretion. + +# Appendix II + +## Sample initialization for the ATM bonding protocol + +As an example of an initialization procedure, assume: + +- Two lines (L1, L2), each of which is trained up with two bearers (B0, B1) both upstream and downstream. +- A bonding group is provisioned as: {DS: L1B0 L2B0; US: L1B0 L2B0} + +A second bonding group could be provisioned as {DS: L1B1 L2B1; US: L1B1 L2B1}: This has no real bearing on the rest, as the second group is independent of the first group. + +![Sequence diagram showing the initialization flow for the ATM bonding protocol between a CO (Central Office) and a CPE (Customer Premises Equipment).](7d2d1d3870cd224c4430d19334557716_img.jpg) + +The diagram illustrates the sequence of messages for ATM bonding initialization between a CO and a CPE. The CO initiates the process by sending ASM (ATM Signaling Messages) on downstream links L1B0 and L2B0. The CPE receives these, performs Group ID and Link ID discovery, and responds with ASMs on upstream links L1B0 and L2B0. The CO confirms the link IDs and proposes transmit (Tx) links to bond. The CPE proposes receive (Rx) links to bond. The CO selects Tx links and proposes Rx links (L1B0 or L2B0). The CPE confirms Rx links and selects Tx links. Finally, the CO confirms Rx links to bond, and both sides start their respective ATM traffic (DS ATM traffic starts at the CO, US ATM traffic starts at the CPE). Vertical ellipses indicate ongoing ASMs throughout the process. + +``` + +sequenceDiagram + participant CO + participant CPE + Note over CO: phy + Note over CPE: phy + CO->>CPE: ASM on DS Link 0: Tx link status: 10 10; Rx link status: 01 01 GID: 1 + Note over CO: L1B0 + CO->>CPE: ASM on DS Link 1: Tx link status: 10 10; Rx link status: 01 01 GID: 1 + Note over CO: L2B0 + Note over CO: Propose Tx links to bond + Note over CPE: Group ID discovery + Note over CPE: Link ID discovery + CPE->>CO: ASM on US Link 0: Tx link status: 10 10; Rx link status: 10 10, GID: 1 + Note over CPE: L1B0 + Note over CO: L1B0 + Note over CO: Confirm link ID + Note over CO: L2B0 + CPE->>CO: ASM on US Link 1: Tx link status: 10 10; Rx link status: 10 10, GID: 1 + Note over CPE: L2B0 + Note over CPE: Propose Rx links to bond + Note over CO: Select Tx links to bond + Note over CO: Propose Rx links to bond + CO->>CPE: DS ASM: Tx link status: 11 11; Rx link status: 10 10, GID: 1 + Note over CO: L1B0 or L2B0 + Note over CPE: Confirm Rx links to bond + CPE->>CO: US ASM: Tx link status: 11 11; Rx link status: 11 11, GID: 1 + Note over CPE: L1B0 or L2B0 + Note over CPE: Select Tx links to bond + Note over CO: L1B0 or L2B0 + Note over CO: Confirm Rx links to bond + CO->>CPE: DS ASM: Tx link status: 11 11; Rx link status: 11 11 GID: 1 + Note over CO: DS ATM traffic starts + Note over CPE: US ATM traffic starts + Note over CO, CPE: On-going ASMs + +``` + +Sequence diagram showing the initialization flow for the ATM bonding protocol between a CO (Central Office) and a CPE (Customer Premises Equipment). + +**Figure II.1/G.998.1 – Example ASM flow during initialization** + +Notes on the timing diagram in Figure II.1: + +The process starts with the CO sending an ASM message on each link in the bonded group. This message has Tx link status set to '10' or '01' for each member of the group, and has the group ID, cell header format, and the link number set to the group, cell header format, and link selected. The Rx link status is set to '01' (or '00' if the link is not provisioned) for each link at this point. + +- 1) After the first error-free downstream ASM message is received at the CPE, the CPE knows the group ID, the cell header format, the physical line/bearer the message arrived on, the number of bearers in the proposed group as well as the bearer for the upstream for that link in that group. It does not know what physical line/bearer the other links in the group will map to, so it cannot decide on the proposed Rx link status for those links yet. +- 2) After the CPE has discovered all the link mappings, it sends a proposed set of links for bonding in the downstream direction by setting Rx link status to '10'. This set is the same or a subset of the links with received Tx link status set to '10'. It is normally the same set unless the CPE wants to exclude one of the links from the group for some reason. +- 3) This ASM message is sent on all the links with the proper link number. This confirms the link mappings and conveys the proposed Rx links for bonding in the downstream direction. At this point there is a complete map of links to physical line/bearers at both the CO and the CPE. +- 4) At this point, the CO selects the set of lines it wants to bond on the downstream from the proposed Rx set from the CPE by setting the Tx link status to '11' for those links. At the same time, it sends a proposed set of upstream Rx links suitable for bonding (Rx link status to '10'), which is the same or a subset of the links with received Tx link status of '10'. +- 5) The CPE confirms the downstream bonding group selection by sending an ASM message with the Rx link status set to '11' and also selects the upstream links it wants to bond by setting the Tx link status to '11'. +- 6) If the received Rx link status at the CO is set to '11' on all the links in a group and the CO previously sent Tx link status of '11' on those links, the bonding group in the downstream direction is confirmed and downstream traffic can be initiated on all the bonded links. In the case of a mismatch in these status fields, the bonding group in the downstream direction may still be confirmed subject to constraints on the aggregate downstream rate as no traffic will flow on the link where Tx link status is '11' and Rx link status is not '11' as per 6.4. In this case, the number of links carrying downstream bonded traffic will be less than provisioned, similar to the case where a link is removed from the set carrying bonded traffic during showtime. +- 7) At this point the CO also confirms the upstream bonding group selection by sending an ASM message with the Rx link status set to '11'. +- 8) If the Rx link status and previously sent Tx link status match at the CPE, the bonding group in the upstream direction is confirmed and upstream traffic can be initiated. In the case of a mismatch in these status fields, the bonding group in the upstream direction may still be confirmed subject to constraints on the upstream aggregate rate as no traffic will flow on the link where Tx link status is '11' and Rx link status is not '11' as per 6.4. In this case, the number of links carrying upstream bonded traffic will be less than provisioned, similar to the case where a link is removed from the set carrying bonded traffic during showtime. + +# Appendix III + +## Link status state machine + +Figure III.1 shows the transition behaviour of a provisioned link. The necessary conditions to allow transition from one link state to the next state based on Tx and Rx status are provided. Regarding the transmitter, when both Tx link status and Rx link status are '11' and the transmitter receives anything for the Rx link status except '11', the transmitter stops forwarding bonded traffic on that link. In all other cases, reception of these Rx link status signals is not sufficient to force a state transition as state transitions are at the discretion of the local end. The near-end transmitter or receiver can transition to a lower Tx or Rx status autonomously. Table III.1 provides additional information on the non-defined status combinations of the link. The only condition in which bonded data is being delivered on a loop is when Tx=11 and Rx=11. Although the condition Tx=00 and Rx=00 is not in Table III.1 and is therefore allowed, it is not shown in the link state diagram because it represents a non-provisioned link, i.e. links not in the group. + +![Link status state machine diagram showing transitions between 'Not in use', 'Standby', and 'Available data' states based on Tx and Rx values.](e05b36c0d46549e681ce6581422c66b2_img.jpg) + +``` + +stateDiagram-v2 + direction TB + state "Not in use\nRx = 01 or Tx = 01" as S1 + state "Standby\nRx = 10" as S2 + state "Available data\nRx = 11 & Tx = 11" as S3 + + S1 --> S1 : Tx = 10 (proposing) & Rx = 01 + S1 --> S2 : Tx = 10 & Rx = 10 (accepted) + S2 --> S1 : Rx = 01 or Tx = 01 or ASM Timeout* + S2 --> S2 : Tx = 11 (proposing) & Rx = 10 + S2 --> S3 : Tx = 11 & Rx = 11 (accepted) + S3 --> S2 : Rx = 10 or Tx = 10 + S3 --> S1 : Rx = 01 or Tx = 01 or ASM Timeout* + +``` + +G.998.1\_FIII.1 + +Link status state machine diagram showing transitions between 'Not in use', 'Standby', and 'Available data' states based on Tx and Rx values. + +Note that moving to higher link state requires Tx & Rx conditions while moving to lower link state requies Tx or Rx conditions. + +\* While ASM Timeout is not explicitly defined in this Recommendation, this example state machine implementation shows how an ASM Timeout may be used to transition states. + +**Figure III.1/G.998.1 – Link status state machine diagram** + +**Table III.1/G.998.1 – Non-defined link status** + +| Tx | Rx | Reason not defined | +|----------|----------|----------------------------------------------------------------------------------------------------| +| 00 | not '00' | Not allowed. An unprovisioned link will always be unprovisioned. Rx and Tx match if unprovisioned. | +| not '00' | 00 | | +| 01 | 10 | Rx cannot consider link for bonding if not proposed by Tx. | +| 01 | 11 | Rx cannot have 'Selected' status unless Tx has 'Selected' status. | +| 10 | 11 | Rx cannot have 'Selected' status unless Tx has 'Selected' status. | +| 11 | 01 | Tx cannot have 'Selected' status unless confirmed by Rx. | + +# Appendix IV + +## Example of algorithm to derive the end-to-end delay + +The receiving bonding application will choose one of the bonded links as the reference link. + +Assume link 0 is the reference link. + +The computation of the differential delay without compensation can be computed as follows: + +- 1) Compute a propagation delay without compensation. +- 2) Compute the differential delay without compensation. +- 3) Compute the average differential delay without compensation. + +Since the final goal is to evaluate the differential delay, the propagation delay without compensation for link $I$ is computed as follows: + +$$Pd(I,t) = timestamp(K(I,t)) - arrival(K(I,t)) - appliedDelay(K(I,t))$$ + +where: + +$Pd(I,t)$ is the propagation delay without compensation on link $I$ at time $t$ + +$K(I,t)$ is the index of the last ASM cell received on link $I$ at time $t$ + +$timestamp(k)$ is the timestamp placed in the ASM with index $k$ + +$arrival(k)$ is the value of the local time when ASM with index $k$ has been received + +$appliedDelay(k)$ is the value of the *appliedDelay* field in the ASM with index $k$ + +About every second, instantaneous differential delay without compensation is computed: + +$$Idd(I,t) = Pd(I,t) - Pd(0,t)$$ + +where: + +$Idd(I,t)$ is the instant differential delay without compensation for link $I$ at time $t$ . The differential delay is computed with link 0 as the reference + +$Pd(I,t)$ is computed as explained above + +The average differential delay without compensation can be computed as the average instant differential delay without compensation computed over the $n$ last seconds. The purpose of this average is to remove the jitter part of the delay. The compensation is not included in order to have an average independent of the different extra delays applied on each line. The differential delay of line $I$ after compensation between lines is equal to: + +$$diffDelay(I,t) = \overline{Idd}(I) + appliedDelay(I,t) - appliedDelay(0,t)$$ + +# **BIBLIOGRAPHY** + +- [B1] ATM Forum Specification af-phy-0086.001 (1999), *Inverse Multiplexing for ATM (IMA) Specification Version 1.* + + + +# **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects 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